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The Morrison Formation is a distinctive sequence of Late Jurassic sedimentary rock that is found in the western United States. It has a vast fossil record, with a wide assortment of taxa represented, including famous dinosaurs like Brachiosaurus, Allosaurus, Diplodocus and Stegosaurus. It is composed of mudstone, sandstone, siltstone and limestone and is light grey, greenish gray, or red in colour. Most of the fossils occur in the green siltstone beds and lower sandstones, relics of the rivers and floodplains of the Jurassic period.
The formation is split into three main members, these are the Salt Wash, Tidwell and Brushy Basin members. Other subdivisions exist in specific areas of the formation, like the Bluff Sandstone Member in the Four Corners region. The most well-studied of these are the Brushy Basin and contemporaneous members, from which most of the iconic Morrison Formation fauna hails.
The rocks of the Morrison Formation were deposited on top of those of the Sundance, Swift, Ralston Creek and Summerville formations, as the Sundance Sea receded to the north and the region became a vast floodplain, fed by rivers coming in from the south and west. Multiple formations also overlie the Morrison, including the ...
Color key
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Notes Uncertain or tentative taxa are in small text; |
Genus | Species | Locality | Material | Notes |
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E. pecki |
Colorado |
Hundreds of specimens at the least |
A genus of freshwater algae in the family Clavatoraceae. | |
E. spinosa | ||||
A. bransonii |
Colorado and Wyoming |
Hundreds of specimens at the least |
A genus of freshwater algae within the family Characeae. | |
A. complanata | ||||
A. jonesii | ||||
A. latisulcata | ||||
A. obovata | ||||
A. rotunda | ||||
C. verticillata |
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C. voluta | ||||
L. bellatula |
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L. collina | ||||
L. concinna | ||||
L. latitruncata | ||||
L. aff. mensinki | ||||
L. spherica | ||||
M. voluta |
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O. oblata |
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P. verticillata |
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P. glypta | ||||
P. voluta |
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P. symmetrica | ||||
P. arguta |
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P. fusca | ||||
P. kimmeridgensis | ||||
P. minima collina | ||||
S. verticillata |
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S. obovata |
Color key
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Notes Uncertain or tentative taxa are in small text; |
Genus | Species | Locality | Material | Notes |
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M. sp. |
To be added |
A genus of Marchantiopsid liverwort. | ||
T. sp. |
A genus of liverwort belonging to the order Metzgeriales . |
Genus | Species | Locality | Material | Notes |
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E. laterale [2] E. bakkeri [3] E. comoensis [3] E. lyelli [2] E. cf. laterale [4] |
Wyoming, Colorado and Utah, Brushy Basin, Lake Como and Temple Canyon Members |
Silicified casts with epidermal features, stem fragments and macrofossil fragments. |
A genus of Equisetacean horsetail. | |
N. sp. |
Genus | Species | State | Member | Material | Notes |
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H. fisheri |
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To be added |
A genus of Dipteridacean fern. | |
C. hymenophylloides |
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O. lemonii |
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A. wadei |
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C. alberta C. heterophylla C. virginiensis |
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G.? sp. A. G.? sp. B. |
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A. montanensis |
incertae sedis | ||||
S. leithii S. medlynii |
incertae sedis | ||||
Indeterminate |
incertae sedis |
Genus | Species | State | Member | Material | Notes |
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S. elliptica |
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To be added |
A genus of Caytoniale. |
Genus | Species | State | Member | Material | Notes |
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C. sp. |
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To be added |
A genus of Cycad with uncertain affinities. | |
J. redmondi |
A genus of Cycad with uncertain affinities. | ||||
N. nigricollensis N. schaumburgensis N. cf. compta |
A genus of Cycad with uncertain affinities. |
Genus | Species | State | Member | Material | Notes |
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Z. arcticus |
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To be added |
To be added | |
O. sp. |
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C. spp. |
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W. sp. |
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A. sp. |
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P. lindstromi P. arcticum P. spp. |
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C. wyomingensis C. spp. |
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C. sp. |
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J. redmondi |
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C. montanese |
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Genus | Species | State | Member | Material | Notes |
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G. cascandensis |
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To be added |
To be added | |
G. pluripartita G. sp. |
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Genus | Species | State | Member | Material | Notes |
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C. turneri C. sp. |
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To be added |
To be added |
Genus | Species | Locality | Material | Notes |
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B. hoodiorum |
Colorado and Utah (Brushy Basin Member) |
More than 300 specimens, three dimensional calcitic casts of a two-seeded compound cone |
Tentatively assigned as a gnetale, with some attributes of the cones pointing towards a close relation with the extant genus Ephedra. | |
D. tetragona |
Henry Mountains of Utah (Brushy Basin Member) |
"Three-dimensional casts and partially permineralized small cones". |
A gnetale with close affinities to Cretaceous and modern genera. |
Genus | Species | State | Member | Material | Notes |
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H. axelrodi |
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To be added |
To be added | |
S. sp. |
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To be added |
To be added | |
T. indet. |
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To be added |
To be added | |
B. rechtenii B. chaneyi B. morrisonense B. spp. |
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To be added |
To be added | |
C. spp. |
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To be added |
To be added | |
P. medlynii |
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To be added |
To be added | |
A. obscurum |
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To be added |
To be added | |
A. hoodi |
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To be added |
To be added | |
P. lanceolatus |
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To be added |
To be added | |
X. morrisonense X. mooreii |
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To be added |
To be added | |
P. resiniferous |
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To be added |
To be added | |
M. obscurum M. carterii |
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To be added |
To be added | |
P. sp. |
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To be added |
To be added | |
P. lindstromii |
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To be added |
To be added | |
S. sp. |
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To be added |
To be added | |
E. sp. |
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To be added |
To be added | |
P. sp. |
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To be added |
To be added | |
B. provoensis B. joannei B. bassii B. scottii |
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To be added |
To be added | |
C. sp. |
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To be added |
To be added | |
S. radiatus |
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To be added |
To be added |
Genus | Species | State | Member | Material | Notes |
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H. kirkbyorum H. taylorii H. glismannii H. owensii |
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To be added |
To be added |
Color key
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Notes Uncertain or tentative taxa are in small text; |
Name | Species | Locality | Material | Notes |
---|---|---|---|---|
Eospongilla [7] | E. morrisonensis |
Colorado |
Two micritic body fossils with calcite-replaced megascleres | A sponge belonging to the class Demospongiae. |
Name | Species | Locality | Material | Notes |
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U. baileyi |
A genus of medium-sized freshwater mussels in the family Unionidae (river mussels). |
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U. felchi |
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U. iroides |
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U. knighti |
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U. lapilloides |
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U. macropisthus |
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U. mammillaris |
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U. nucalis |
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U. stewardi |
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U. s. utahensis |
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U. toxonotus |
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U. willistoni |
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V. faberi |
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V. mayoworthensis |
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V. whitei |
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H. jurassicus |
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H. lateralis |
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H. trigonus |
Name | Species | Locality | Material | Notes |
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M. morrisonensis |
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A. cyclostoma A. scabrida A. s. leesi A. ? reesidei |
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V. morrisonensis V. reesidei |
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L. jurassicus |
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R. gilloides R. jurassica |
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L. jurassica |
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T. jurassica |
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"P." altispiratum |
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A. gilloides A. jurassica |
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L. jurassica |
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L. ativuncula L. consortis L. morrisonensis |
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G. veternus |
Name | Species | Locality | Material | Notes |
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C. cf. tendaguruensis |
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E. sp. |
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L. tendagurensis |
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L. sp. A. |
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L. sp. B. |
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N. krasinetzi |
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D. acuminata |
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D. cf. dakotensis |
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C. atlantosaurica |
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C. marshi |
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Simplus |
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C. purbeckensis |
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C. coloradensis |
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C. morrisonensis |
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B. pahasapiens |
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B. pustulosa |
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M. bradyi |
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M. minnekahtensis |
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M. whitei |
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G. sp. |
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H. petersoni |
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H. prima |
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H. turneri |
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T. guimarotensis |
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D. pustulosa |
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T. wyomingense |
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C. acuticyatha |
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R. jurassica |
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C. armata |
This genus is of uncertain placement. | |||
C. striata |
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C. sp. |
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T. aff. rothi |
Genus is of uncertain placement. | |||
cf. Cambaridae indet. |
Name | Species | Locality | Material | Notes |
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E. ekdalei |
Utah, Brushy Basin member |
Nests produced by social insects. [8] |
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Morrisonnepa [9] | M. jurassica |
Utah |
A hemipteran belonging to the group Nepomorpha. | |
Parapleurites [10] | P. morrisonensis |
Colorado |
a forewing. | A Locustopsid orthopteran |
T. kollaspilus |
Colorado, Brushy Basin member |
Five specimens were reported in the original description of the ichnogenus. |
Color key
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Notes Uncertain or tentative taxa are in small text; |
Although the paleoclimate of the Morrison formation was semiarid with only seasonal rainfall, there were enough bodies of water to support a diverse ichthyofauna. [11] Although abundant, fish remains are constrained to only certain locations within the formation, with microvertebrate sites in Wyoming especially being dominated by fish remains. [11] Indeterminate remains of ray-finned fish have been recovered from Ninemile Hill and a microvertebrate site in the Black Hills. [11] Morrison actinopterygians have been found in stratigraphic zones 2, 4, and 5, and generally have no close modern relatives. [11] The Wyoming microvertebrate remains are extracted from the sediment by screenwashing. [11] Paleoniscoid remains are geographically present in the western part of Colorado, where remains have been recovered from "a level above the Mygatt-Moore Quarry." [11] Largely complete remains of small individuals have been consistently recovered for over 15 years. [11] So far, Morrison pycnodontoids are represented by a single specimen from Dinosaur National Monument in Utah. [12] Found in stratigraphic zone 4. [13] Only a single specimen from Dinosaur National Monument in Utah has been recovered. [12] Pycnodontoids were "deep-bodied and laterally compressed fish" whose tooth morphology suggest that they preyed on small contemporary invertebrates. They may have resembled modern butterfly fish. [12] A single tooth is the only known remains. [12] Dipnoan remains found at a fossil site not far from Cañon City, Colorado. [11] Remains usually in a state of rather complete preservation. [11] Halecostome remains are geographically present in the western part of Colorado, where remains have been recovered from "a level above the Mygatt-Moore Quarry." [11] Largely complete remains of small individuals have been consistently recovered for over 15 years. [11] Amiid remains found in stratigraphic zones 2, 3, and 4. [13] Found at a fossil site not far from Cañon City, Colorado. [11] Remains usually in a state of rather complete preservation. [11]
Name | Species | Locality | Material | Notes | Images |
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C. fossanovum [11] |
A lungfish genus whose members ranged from 1 to 2 m in length and weights of up to 79 pounds, with most Morrison lungfish being on the smaller end of that range. [11] These species are believed to have had similar diets to extant lungfish like the physically similar modern genus Neoceratodus. [11] |
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C. ?frazieri [11] |
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C. guentheri [11] |
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C. robustus [11] |
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Indeterminate. |
Brushy Basin and Saltwash members |
Represented by tooth plates. | |||
H. hawesi [15] |
Colorado |
A small fish of the division Halecostomi about 7.6 cm in length and 5g of live mass which probably preferred quiet water. Its fossils prominently preserve its thick interlocking scales. | |||
cf. Leptolepis [14] |
N/A |
Colorado [15] |
Known only from a single nearly complete skeleton found at Rabbit Valley. [16] Found in stratigraphic zone 5. [13] |
A 13 cm (5 inch) fish that was deeper bodied than its co-occurring contemporaries Morrolepis and Hulettia. [16] The Morrison cf. Leptolepis probably had a live mass of about 37g. [16] It is the only teleost fish known from the formation and was morphologically more highly derived than other Morrison fish. [16] It is believed to have fed on contemporary fish and small invertebrates. [16] | |
M. schaefferi [17] |
Colorado |
A coccolepid " palaeoniscoid" with forward-set eyes positioned past the front end of the lower jaw. It had a tall dorsal fin set far back on the body and an asymmetrical caudal fin. [17] Adult specimens would reach about 20 cm in length and 113 g (4 oz) in mass. [17] | |||
P. guentheri |
Colorado |
Once thought to be a species of Ceratodus. |
Frogs are known from several sites in the Morrison Formation, but are not particularly well represented. [18] The history of Morrison anuran discoveries began with the recovery of remains from Quarry 9 near Como Bluff, Wyoming. The new genus Eobatrachus was erected for some of these remains by O. C. Marsh, but the material was later considered non-diagnostic. Decades later another dubious anuran genus, Comobatrachus, was erected based on additional fragmentary remains. Despite the erection of multiple new names, only two frog species are currently recognised from the Morrison: Enneabatrachus hechti [19] and Rhadinosteus parvus. [20]
In addition to formally named taxa, indeterminate anuran remains have been recovered from Morrison strata in Colorado, Wyoming, and Utah, with the best specimens found in Dinosaur National Monument and Quarry 9. [18] Stratigraphically speaking, indeterminate anurans have been found in stratigraphic zones 2 and 4. [13] Indeterminate anurans with remains diagnostic down to the family level have also been reported from the Morrison, with pelobatids being represented by the illium of an unnamed and indeterminate species, which was recovered from Quarry 9. [21] Pelobatids are present in stratigraphic zones 5 and 6. [13]
Indeterminate salamander remains are present in stratigraphic zones 2, 4, and 5. [13] A distinctive type of salamander known only as Caudata B is present in stratigraphic zone 6. [13]
Name | Species | Locality | Material | Notes |
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C. aenigmaticus |
Wyoming, Brushy Basin member [18] |
A partial right humerus. [22] |
A dubious genus of prehistoric frog erected by O. C. Marsh to house fragmentary remains recovered from Reed's Quarry 9 near Como Bluff Wyoming. [18] Along with Eobatrachus it was among the earliest frog remains from the formation, although the two dubious genera were erected decades apart. [18] | |
C. marshi [23] |
Wyoming, Brushy Basin member [23] |
Represented by a single femur. [23] |
Considered a nomen dubium because the name is based on non-distinctive remains which cannot be classified in detail. [23] | |
E. hechti [19] |
A small discoglossid frog whose live weight would have only been a few grams. [19] | |||
E. agilis |
Wyoming, Brushy Basin member [18] |
A partial right humerus. [22] |
A dubious genus of prehistoric frog erected by O. C. Marsh to house fragmentary remains recovered from Reed's Quarry 9 near Como Bluff Wyoming. [18] Along with Comobatrachus it was among the earliest frog remains from the formation, although the two dubious genera were erected decades apart. [18] | |
I. hechti |
A partial skull and incomplete postcranial skeleton. [25] |
A basal salamandroid closely related to today's advanced salamanders. | ||
R. parvus [20] |
Utah |
Known from several slabs of rock which contain multiple partial specimens in association. [20] |
A pipoid and possible rhinophrynid, Rhadinosteus parvus was only about 42 mm (1.6 inches) long in life. [20] | |
Anura? | Indeterminate | Dinosaur National Monument, Colorado/Utah and Quarry 9, Wyoming. | multiple specimens? | (see text) |
Pelobatidae? | Indeterminate | Stratigraphic zones 5 and 6 | (see text) | |
Pelobatidae? | Indeterminate | Quarry 9, Wyoming | an illium | (see text) |
Caudata? | Indeterminate | Stratigraphic zones 2, 4 and 5 | (see text) | |
Caudata? | "B." | Stratigraphic zone 6 | (see text) |
Name | Species | Locality | Material | Notes | Images |
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E. robustus |
Colorado |
Several fragmentary skull, mandible, and tooth elements. |
A herbivorous eilenodontine of relatively large size. |
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O. rarus |
Colorado, Utah and Wyoming, Brushy Basin member |
Several skulls and partial skeletons. |
A sphenodontian similar in appearance to the modern Tuatara |
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O. gregori |
Northern Wyoming, possibly west-central Colorado. Brushy Basin Member |
Most of the skull and postcranium |
A small-bodied eusphenodontian, and one of the most complete rhynchocephalian taxa yet known from North America. |
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T. antiquus |
Wyoming, Brushy Basin member |
A mandible. |
A small sphenodontian. |
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Sphenodontia [26] | Indeterminate | Dinosaur National Monument | A crushed partial skull (DINO 16454) | The specimen is undescribed. Although previously considered to have belonged to Opisthias or Theretairus, recent studies have doubted this referral, thus placing it as an indeterminate sphenodont. [26] |
Numerous squamate remains have been found in the sediments of the Morrison Formation, most commonly at sites in Utah, Colorado and Wyoming. A number of taxa have been described, coming from three different groups: anguimorph and scincomorph lizards and early snakes. [27] [28] [29] The first squamates to be reported from the Morrison Formation were Paramacellodus and Dorsetisaurus, which were described from Wyoming's Quarry 9 by Don Prothero and Richard Estes. [27] Later remains would include Diablophis, originally described as a species of Parviraptor by Susan Evans in 1996 [30] but subsequently moved to the new genus Diablophis by Michael Caldwell et al. in 2015, with extra material also being reported from Utah's Cisco Mammal Quarry, and Schillerosaurus, originally described as "Schilleria" and reported from Dinosaur National Monument by Evans and Dan Chure in 1999. [31] Two later additions to the Morrison's squamate assemblages are Eoscincus and Microteras, two scincomorph lizards found at Dinosaur National Monument and Como Bluff's Quarry 9, respectively. They were described by Chase Brownstein et al. in 2022. [28] Indeterminate squamate remains have currently been described from Dinosaur National Monument. [31]
The majority of modern-day scincomorph lizards are small insectivores that feed on a range of invertebrates. [32] It is thought that their counterparts from the Morrison Formation would have occupied a similar niche due to their morphological similarities. Anguimorph lizards most likely hunted small vertebrates, and Diablophis is thought to have done so too. Prey items would have included the other squamates from the formation as well as its large diversity of small mammals. All squamates might have been prey for the larger predators of the Morrison Formation, including the abundant theropod dinosaurs and crocodilians.
Name | Species | Locality | Material | Notes |
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D. gilmorei |
Fruita Palaeontological Area, Colorado and Cisco Mammal Quarry, Utah (Brushy Basin Member) |
A broken right maxilla, broken right mandible and broken right dentary. Broken axis vertebrae, precloacal vertebrae, one caudal vertebra and a possible sacral vertebra have also been found. [29] |
A basal snake. [29] Originally described as a species of Parviraptor, [14] subsequently moved to its own genus. [29] | |
D. sp. |
Quarry 9 at Como Bluff, Wyoming, Utah and Colorado (Brushy Basin Member) |
An anguimorph lizard. | ||
E. ornatus |
Site 412 at Dinosaur National Monument, Utah (Brushy Basin Member) |
The holotype specimen, DINO 14864, includes a complete rostrum and palate, a partial skull roof, and both mandibles. |
A scincomorph lizard. | |
Helioscopos [33] | H. dickersonae | Site 317 at Dinosaur National Monument, Utah (Brushy Basin Member) | The holotype specimen, DINO 15914, consists of a partial skull and mandibles, lacking the anterior snout. | A stem- gecko. |
M. borealis |
Quarry 9 at Como Bluff, Wyoming (Brushy Basin Member) |
The holotype specimen, YPM VP 4718, consists of an associated maxilla and braincase. |
A scincomorph lizard. | |
P. sp. |
Fruita Palaeontological Area & Rainbow Park, Colorado and Quarry 9 at Como Bluff, Wyoming (Brushy Basin Member) |
Several jaws, two skulls, isolated jaw elements, osteoscutes and a small block bearing the posterior trunk vertebrae and hind limbs with a few ventral osteoscutes. Possibly a left prefrontal and postcranial material consisting of a scapulocoracoid, a trunk vertebra and multiple articulated bones consisting of a partial pelvis, seven caudal vertebrae and a nearly complete left hind limb. [27] [31] |
A small scincomorph lizard with blunt teeth. | |
S. sp |
Fruita Palaeontological Area, Colorado (Brushy Basin Member) |
A scincomorph lizard whose remains have been found in Middle Jurassic strata in England and Scotland as well as Late Jurassic strata in Portugal in addition to the Morrison formation remains. [34] | ||
Dinosaur National Monument, Utah (Brushy Basin Member) |
Part and counterpart of a partial dissociated skeleton and a few limb bone fragments. [31] |
A small scincomorph lizard of otherwise uncertain evolutionary affinities. [36] It is the only lizard genus endemic to the Morrison Formation. [36] | ||
Indeterminate |
Dinosaur National Monument, Utah (Brushy Basin Member) |
Specimen DNM 14720, a disarticulated skeleton and DNM 14734, a fragmentary skeleton. [37] |
Squamates of uncertain affinities. Noted as distinct from Paramacellodus and Dorsetisaurus, of which remains have been found in the same quarry. [31] |
Turtles ( Testudines) are very common fossils in the Morrison, due to their bony shells. The most common were Glyptops plicatus (very common) and Dinochelys whitei (also common, but not as common as Glyptops). Also present were Dorsetochelys buzzops and Uluops uluops.
Name | Species | Locality | Material | Notes |
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Colorado and Utah, Salt Wash member |
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C. plicatulus |
Colorado |
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D. whitei [38] |
Colorado, Utah and Wyoming, Brushy Basin member [38] |
Several shells and some postcranial material. [38] |
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D. buzzops |
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G. plicatulus [38] |
Colorado and Wyoming, Brushy Basin member [38] |
Several shells, skulls, and partial skeletons. [38] |
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G. ornatus [39] |
Synonym of Glyptops plicatulus. [38] | |||
G. utahensis [40] |
A complete shell. [40] |
Synonym of Glyptops plicatulus. [38] | ||
U. uluops |
Como Bluff, Wyoming, Brushy Basin member [41] |
A cranium. [41] |
Most basal Pleurosternid from the Morrison Formation. [41] |
Name | Species | Locality | Material | Notes |
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C. antiquus |
Colorado, Oklahoma, South Dakota, Utah and Wyoming |
A champsosaur about 25 to 50 cm in length. |
Crocodiles of a variety of sizes and habitats were common Morrison animals. Cursorial mesosuchians, or small terrestrial running crocs, included Hallopus victor and Fruitachampsa callisoni. More derived crocodilians included Diplosaurus ferox, Amphicotylus, Hoplosuchus kayi, and Macelognathus vagans.
Name | Species | Locality | Material | Notes | Images |
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A. gilmorei |
Wyoming |
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A. lucasii |
Colorado |
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A. milesi |
Wyoming, Brushy Basin member [43] |
A nearly complete skeleton. [43] |
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A. stovalli |
Oklahoma |
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D. felix |
Colorado |
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E. delfsi |
Colorado and Wyoming |
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F. callisoni |
Colorado, Brushy Basin and Saltwash members |
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H. victor |
Colorado, Brushy Basin member [45] |
A partial skeleton including a fragmentary skull roof. [45] |
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H. sanjuanensis |
Colorado and Utah |
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H. sp. |
Utah and Wyoming, Salt Wash member |
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H. kayi |
Arizona and Utah |
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M. vagans |
Colorado and Wyoming, Brushy Basin member [46] |
A partial left mandible (type) and several fragmentary referred fossils. [46] |
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T. morrisonensis |
Wyoming |
A nearly complete left mandible missing teeth. |
Pterosaurs are very uncommon fossils in the Morrison, because the fragility of their thin walled bones often prevented their remains from being preserved. [48] Despite being uncommon they are geographically widespread; [49] indeterminate pterosaur remains have been found in stratigraphic zones 2 and 4-6. [13] In addition to indeterminate remains, several species have been identified from both the rhamphorhynchoids (long-tailed pterosaurs) and pterodactyloids (short-tailed pterosaurs). [48] Since the 1970s and 80s, pterosaur finds have become more common, but are still rare. [48] Most Morrison pterosaurs have been found in marine and shoreline deposits. [48] Pterosaur tracks have been found in both the Tidwell and Saltwash members. [48] Morrison pterosaurs probably lived on fish, insects and scavenged dinosaur carcasses, or even foraged for prey, and actively hunted; [48] they are fairly ecologically diverse, ranging from small hawking insectivore Mesadactylus to the raptorial Harpactognathus. While relatively few pterosaur genera are named from the Morrison Formation, fragmentary material that is not referrable to the genus level suggests the presence of dsungaripteroids, ctenochasmatids, dimorphodontids, and more tentatively wukongopterids and pteranodontians. [50] [51] [52] [53]
Name | Species | Locality | Material | Notes | Images |
---|---|---|---|---|---|
C. ostromi |
Wyoming, Brushy Basin member |
A metacarpal. |
|||
D. montanus |
Wyoming, Brushy Basin member |
A wing phalanx. |
|||
H. gentryii |
Wyoming, Brushy Basin member |
A partial snout. |
A large rhamphorhynchid with a wingspan of about 2.5 m and live mass of about 1.5 kg (3.3 lbs). [54] Harpactognathus was related to the Solnhofen genus Scaphognathus. [54] | ||
K. insperatus |
Colorado, Brushy Basin member |
A partial postcranial skeleton. |
A large pterodactyloid with a 2.5 m (8 foot) wingspan and a live weight of about 1.5 kg (3 lbs). [55] Kepodactylus may be related to the Asian dsungaripteroid pterosaurs. [55] | ||
L. priscus |
Wyoming, Brushy Basin member |
A braincase. |
Nomen dubium initially misidentified as a bird. | ||
M. ornithosphyos |
Colorado, Brushy Basin member |
A synsacrum. | Several specimens have been incorrectly referred to Mesadactylus. [51] [52] | ||
P. saltwashensis'* |
Arizona and Oklahoma, Saltwash member |
||||
U. kateae |
Utah, Tidwell member |
A fragmentary skeleton. |
Previously thought to be an indeterminite diapsid, newer material suggests an affinity with ctenochasmatids. [53] |
The herbivorous ornithischian dinosaurs were diverse but not as common as sauropods in the Morrison. Fruitadens, previously known as the "Fruita Echinodon", was found to be a heterodontosaurid. Plate-backed stegosaurids included Hesperosaurus mjosi, Stegosaurus armatus, S. ungulatus, S. stenops, and Alcovasaurus longispinus. Armored dinosaurs that weren't stegosaurs were unknown in the formation until the 1990s. Two have been named: Gargoyleosaurus parkpinorum and Mymoorapelta maysi. Ornithopods, bipedal herbivores, came in several types. Small " hypsilophodonts" included Drinker nisti, Laosaurus celer, "L." gracilis, Nanosaurus agilis, Othnielia rex, and Othnielosaurus consors (all of which are now synonymous with Nanosaurus). Larger but similar-looking dryosaurids were represented by Dryosaurus altus and the camptosaurid Uteodon aphanoecetes, which is currently known only from Dinosaur National Monument. Still larger was the more common Camptosaurus dispar. Dryosaurids and camptosaurids were early iguanodonts, a group that would later spawn the duck-billed dinosaurs.
Morrison ornithopod trace fossils are represented by three toed tracks which are generally small. [57] The toes of Morrison ornithopod tracks are usually more widely splayed than the theropod tracks preserved in the formation. [57] Stegosaur tracks were first recognized in 1996 from a hindprint-only trackway discovered at the Clevland-Lloyd quarry, which is located near Price, Utah. [58] Two years later, a new ichnogenus called Stegopodus was erected for another set of stegosaur tracks which were found near Arches National Park, also in Utah. [58] Unlike the first, this trackway preserved traces of the forefeet. Fossil remains indicate that stegosaurs have five digits on the forefeet and three weight-bearing digits on the hind feet. [58] From this, scientists were able to successfully predict the appearance of stegosaur tracks in 1990, six years in advance of the first actual discovery of Morrison stegosaur tracks. [58] Since the erection of Stegopodus, more trackways have been found, however none have preserved traces of the front feet, and stegosaur traces remain rare. [58]
Genus | Species | State | Member | Material | Notes | Images |
---|---|---|---|---|---|---|
C. amplus [59] |
Now known to be based on a theropod foot. [61] |
|||||
C. aphanoecetes [62] |
|
|
Reclassified as Uteodon. | |||
C. browni [63] |
Junior synonym of C. dispar. [64] | |||||
"[Twenty-five to thirty] disarticulated skull elements, some with associated postcrania, approximately [ten] partial, articulated skeletons, juvenile to adult." [69] |
A member of Camptosauridae. Junior synonyms include Camptosaurus browni, C. medius, and C. nanus. | |||||
C. medius [63] |
Junior synonym of C. dispar. [64] | |||||
C. nanus [63] |
Junior synonym of C. dispar. [64] | |||||
D. nisti [70] |
"Partial skull and postcranial skeleton." [72] |
A basal neornithischian about 2 m long, slightly smaller than Othnielosaurus. [70] Junior synonym of Nanosaurus agilis [73] | ||||
D. altus [65] |
|
The remains of many individuals have been uncovered, with some sites containing hundreds of bones from Dryosaurus of multiple age groups. [74] |
A large dryosaurid iguanodont up to 2.4 m (7.9 feet) long and 114 kg (251 lbs) in weight. It was physically similar to Othnielosaurus, although larger and with more derived teeth. [75] | |||
D. elderae [73] |
|
|
A 2 partial skeletons, one a juvenile, and 2 additional fragmentary specimens. |
A large dryosaurid iguanodont up to 2.4 m (7.9 feet) long and 114 kg (251 lbs) in weight. It was physically similar to Othnielosaurus, although larger and with more derived teeth. [75] | ||
" Laosaurus" |
L. altus |
Now known as Dryosaurus altus | ||||
L. celer |
|
Considered dubious due to fragmentary remains. | ||||
L. consors |
Now known as Othnielosaurus consors | |||||
"L. gracilis" |
Considered dubious due to fragmentary remains. | |||||
N. agilis |
|
|
A small basal Neornithischian known from dozens of individuals. [73] The holotype, YPM VP 1913, is a fragmentary skeleton from a juvenile. [73] | |||
O. rex [41] |
|
|
Based on an isolated femur. [41] |
A small neornithischian 2 m in length. Dubious; many remains historically assigned to this taxon are now place within Nanosaurus. | ||
O. consors |
A basal neornithischian about 2 m long. Junior synonym of Nanosaurus agilis [73] | |||||
T. aequifacies |
|
"Vertebrae." [77] |
||||
T. lucasanus |
|
"Vertebra." [77] | ||||
U. aphanoecetes [62] |
|
|
||||
G. parkpinorum [78] |
|
"Skull [and] partial postcranium." [79] |
A polacanthine nodosaur known from reasonably complete fossil remains. Its skull measures 29 centimeters (11 in) in length, and its total body length is an estimated 3 to 4 meters (9.8 to 13.1 ft.). It may have weighed as much as 1 tonne (2,200 lb.). [78] |
|||
H. mjosi [80] |
|
"Complete skeleton with skull, subadult." [81] Known only from a single specimen. [80] |
A stegosaurine stegosaurid that was slightly smaller and more primitive than Stegosaurus itself. H. mjosi had a broader skull and longer, lower plates. Considered by some to be a species of Stegosaurus [39] | |||
M. longispinus |
|
|
"Fragmentary postcranial skeleton, adult." [82] |
A dacentrurinae stegosaurid physically similar to Stegosaurus stenops but with much larger tail spines. [83] It is also similar to Kentrosaurus in having long dermal spikes on the caudal region. [53] The thighbone length was determined at 1082 millimeters. The longest spike was 86 centimeters long. Its point was broken and it is estimated the original length of the bone core at 985 millimeters. In 2019, the genus Alcovasaurus was considered a junior synonym of Miragaia [84] | ||
M. maysi [67] |
|
|
"Skull fragments, portions of [three] skeletons, [and] other postcrania." [85] |
Both the first ankylosaur discovered in the formation and the first known North American Jurassic ankylosaur. [86] It probably weighed 500 kg (1,102 lbs) in life. [86] | ||
S. armatus [65] |
|
|
Several caudal vertebrae and assorted fragmentary postcranial elements. [40] |
S. armatus is both the first Stegosaurus to be discovered and the type species. [87] Its type specimen is poorly preserved, incomplete, and lacks diagnostic features. [40] It has been considered dubious, with S. stenops as the neotype species for the genus. [40] | ||
S. stenops [65] |
|
"[Two] complete skeletons with skulls, [four] braincases, at least [fifty] partial postcrania, juvenile to adult." [82] |
The best known Stegosaurus species, it has shorter limbs and larger plates than S. ungulatus. [89] | |||
S. sulcatus [65] |
|
Several postcranial elements, including a possible shoulder spike. [40] |
Often considered synonymous with S. stenops, [91] it may be distinct. Potentially has a shoulder spike, otherwise unknown in Stegosaurus, despite presence in relatives. [40] | |||
S. ungulatus [65] |
|
Several partial skeletons, including a partial braincase. [40] |
S. ungulatus had longer limbs and comparatively smaller plates than the better known S. stenops. [92] Although formerly portrayed with eight tail spikes, it is now known to have had the typical four. [93] Possibly synonymous with S. stenops. [39] | |||
Indeterminate. [94] |
||||||
F. haagarorum [95] |
|
|
A partial skull and mandible with several postcranial elements. [97] |
Sauropods, the giant long-necked long-tailed four-legged herbivorous dinosaurs, are among the most common and famous Morrison fossils. A few have uncertain relationships, like "Apatosaurus" minimus (possibly a basal titanosauriform) and Haplocanthosaurus. Sauropods including Haplocanthosaurus priscus, H. delfsi, and the diplodocid Eobrontosaurus appeared in the early stages of the Morrison. The middle stages were dominated by familiar forms such as the Giraffe-like Brachiosaurus altithorax, which were uncommon, but related camarasaurids, like Camarasaurus supremus, C. grandis, C. lentus, and Cathetosaurus, were very common. Also common were long, low diplodocids, like Apatosaurus ajax, A. louisae, Brontosaurus excelsus, B. parvus, Barosaurus lentus, Diplodocus longus, D. carnegii, Galeamopus and Dyslocosaurus polyonychius.
By the late Morrison, gigantic diplodocids (or likely diplodocids) had appeared, including Diplodocus hallorum (formerly Seismosaurus), Supersaurus vivianae, Amphicoelias altus, and M. fragilimus. Smaller sauropods, such as Suuwassea emiliae from Montana, tend to be found in the northern reaches of the Morrison, near the shores of the ancient Sundance Sea, suggesting ecological niches favoring smaller body size there compared with the giants found further south. [98]
Genus | Species | Locality | Material | Notes | Images |
---|---|---|---|---|---|
H. delfsi [67] |
Colorado [67] |
Partial skeleton lacking a skull. [99] |
Small haplocanthosaurs of indeterminate classification, ranging about 14 m (46 ft) long. |
||
H. priscus [67] |
Two skulless partial skeletons. [99] | ||||
M. fragillimus [67] |
Colorado, Brushy Basin member [67] |
A single, now lost, dorsal neural arch. [100] |
Large rebbachisaurid. Based on a single lost neural arch 1.5 m (5 ft) tall. [100] | ||
D. polyonychius |
Wyoming [10] |
A fragmentary forelimb and partial hindlimbs. | Phylogenetic placement is uncertain. [10] | ||
Colorado, Brushy Basin member [67] |
"Partial skull and cervicals." [102] |
A dicraeosaurid sauropod. Originally described as "Morosaurus" agilis. [101] | |||
S. emilieae |
Montana, Brushy Basin member [103] |
A partial skull and some postcrania. [98] |
A dicraeosaurid about 15m in length. | ||
A. altus [67] |
Colorado, Brushy Basin member [67] |
2 dorsal vertebrae, femur, and a pubis. [104] |
Large diplodocids about 25 m (82 ft) in length. [105] | ||
A. ajax [67] |
Colorado, Brushy Basin member [67] |
A partial postcranial skeleton and posterior skull. [10] |
Robust and abundantly wide-spread apatosaurine diplodocids reaching lengths of up to 25 m (82 ft). [106] "A." minimus likely belongs to a separate genus. | ||
A. louisae [65] |
Colorado and Utah, Brushy Basin member [65] |
Four partial specimens, one of them including a skull. [10] Three of the specimens are from DNM, one is a mid cervical from Como Bluff. [10] | |||
"A." minimus |
Wyoming [60] |
"Sacrum and pelvis." [102] | |||
A. montanus |
Colorado, Brushy Basin member [41] |
A partial sacrum that cannot be distinguished from Camarasaurus or Apatosaurus. [43] |
Dubious neosauropod. [43] | ||
B. excelsus |
Two postcranial skeletons. [10] |
Previously considered a species of Apatosaurus as per Riggs (1903). | |||
B. parvus |
Utah and Wyoming, Brushy Basin and Salt Wash members |
Three headless skeletons. [10] |
Originally called Elosaurus. | ||
B. yahnahpin [10] |
Wyoming, Brushy Basin member |
A partial postcranial skeleton. [10] |
An apatosaurine diplodocid slightly more primitive than Apatosaurus. Formerly placed in separate genus Eobrontosaurus. | ||
B. lentus [65] |
2 partial postcranial skeletons, with possibly more specimens assignable. [10] |
A diplodocid about 24 m (79 ft) in length, similar in appearance to Diplodocus.It was the rarest sauropod in the Morrison Formation. [109] | |||
B. sp |
Wyoming, Utah and Oklahoma | ||||
D. carnegii [65] |
Known from two skulls, five partial skeletons that lack skulls and manus, and hundreds of isolated postcranial remains. [111] |
Large diplodocids reaching lengths of up to 28 m (92 ft). It was one of the most abundant sauropods in the area. [112] | |||
D. hallorum |
New Mexico, Utah and Wyoming, Brushy Basin and Salt Wash members [94] |
At least 4 partial postcranial skeletons [10] |
Once classified as Seismosaurus. [113] [114] [115] [116] | ||
D. lacustris [67] |
Colorado [67] |
Known from teeth and skull remains, the latter now referred to Camarasaurus. [10] Teeth cannot be referred beyond Flagellicaudata. [10] | |||
D. longus [65] |
Colorado [67] |
Several caudal vertebrae. [117] | |||
G. hayi |
Known from a partial skeleton and braincase. [111] | ||||
G. pabsti |
Colorado and Wyoming, Brushy Basin member |
A skull and partial postcranial skeleton, another individual known from partial skull. [10] | |||
K. siberi |
Wyoming, Salt Wash member [118] |
Skull and cervical vertebrae. [118] | |||
S. vivianae [67] |
Colorado and Wyoming |
Known from several partial postcranial skeletons. [104] |
A large diplodocid about 33–34 m 108–111 ft) in length | ||
B. altithorax [14] |
Colorado, Brushy Basin and Salt Wash members [67] |
Several partial skeletons and a partial skull. |
A large brachiosaurid about 26 m (85 ft) long. |
||
C. annae [65] |
Utah, Brushy Basin member [65] |
A dorsal vertebra. |
Camarasaurs reached an adult size of about 18 m (60 ft) in length. [119] C. annae junior synonym of C. lentus. C. lewisi was originally described as Cathetosarus lewisi and was later sunk into Camarasaurus, until being considered valid once again in 2013. C. lewisi has been considered a seperate species (Cathetosaurus), and might still be a genus distinct from Camarasaurus. [120] | ||
C. grandis [67] |
"At least 6 partial skeletons including 2 skulls, hundreds of postcranial elements." [99] | ||||
C. lentus [65] |
"5 skeletons with skulls, hundreds of postcranial elements" [99] | ||||
C. lewisi [67] |
Colorado [67] |
"Nearly complete postcranial skeleton." [99] | |||
C. supremus [67] |
At least 4 partial skeletons including partial skulls. Many possible postcranial remains from Oklahoma. [22] | ||||
Indeterminate. |
|||||
Dystrophaeus | D. viaemalae [9] |
Utah, Tidwell member [9] |
Multiple vertebrae, teeth and incomplete forelimb material. [9] | Previously recovered as a diplodocid, now recovered as a macronarian [9] Type material fragmentary, but recent rediscovery of type locality has discovered more material. [123] |
Theropod dinosaurs, the carnivorous dinosaurs, came in several different types. The less derived types, the ceratosaurs and megalosaurids, included Ceratosaurus nasicornis, C. dentisulcatus, C. magnicornis, Elaphrosaurus sp., and the megalosaur Torvosaurus tanneri (including Edmarka rex). Allosaurids included the common Allosaurus fragilis (including Epanterias amplexus), Allosaurus new species, A. lucasi, and giant Saurophaganax maximus (potentially included in Allosaurus?). Also a recently discovered dinosaur has turned out to be a new species, not Allosaurus. It's a proceratosaurid tyrannosauroid.
Indeterminate theropod remains have been recovered in Utah. Indeterminate theropod tracks have been recovered from both Utah and Arizona. [124]
Genus | Species | Locality | Material | Notes | Images |
---|---|---|---|---|---|
A. fragilis [65] |
Colorado, New Mexico, Oklahoma, South Dakota, Utah and Wyoming, Brushy Basin member [67] [94] [68] [108] [60] [125] |
"At least [three] complete skulls, many partial skulls and skull elements, many partial and complete skeletons representing at least 60 individuals." [126] It was the most common large carnivore in the area. [127] [128] [38] |
|||
A. jimmadseni [129] |
Wyoming and Utah, Brushy Basin and Salt Wash members [125] [38] |
At least 15 specimens, including several skulls. | |||
A. valens |
Colorado [45] |
Half of a proximal caudal centrum | |||
C. atrox |
Wyoming, Brushy Basin member [130] |
A fragmentary skull and assorted postcrania. [130] |
Considered a junior synonym of Allosaurus. | ||
E. amplexus |
Colorado, Brushy Basin member [25] |
Several fragmentary postcranial elements of 2 individuals, [131] possible additional remains known from Wyoming. [132] | |||
L. lucaris |
Wyoming, Brushy Basin member [45] |
A fragmentary skull and several postcranial elements. [46] [45] |
Junior synonym of A. fragilis. [45] | ||
L. ferox |
Wyoming, Brushy Basin member [45] |
A partial skull, dentaries, and fragmentary postcrania. [133] [45] |
Known from one specimen with several pathologies. Today considered a junior synonym of A. fragilis. [45] | ||
S. maximus [68] |
Several partial postcranial skeletons and fragmentary skull material. [45] [51] [125] |
Generally considered to be its own genus. Sometimes considered to be a species of Allosaurus. [134] [135] | |||
C. fragilis [65] |
"Postcranial skeleton." [136] |
A basal coelurosaurian about 2.3 m (7.5 ft) long. | |||
Indeterminate. [67] |
Colorado [67] |
||||
H. miessleri |
Wyoming |
An early troodontid. | |||
K. douglassi [65] |
Utah [65] |
A small theropod thought to be one of the oldest known troodontids. | |||
P. thomsoni [67] |
Colorado, Brushy Basin member [67] |
A distal radius | |||
O. hermanni [65] |
"Skull and associated postcranial skeleton." [136] |
A small basal coelurosaurian about 2 m (6.5 ft) long. | |||
S. clevelandi [65] |
Utah [65] |
"Illium, associated elements and pelvic cranial material. [sic]" [138] |
A possible early tyrannosauroid about 4 m (13 ft) in length. | ||
T. topwilsoni |
Utah |
A basal coelurosaurian about 3.4 m (11.3 ft) long, similar in appearance to Coelurus. | |||
E. rex [60] |
Wyoming [60] |
Junior synonym of Torvosaurus tanneri. | |||
M. bicentesimus [65] |
Partial skeleton, including part of a skull. [139] |
A medium-sized piatnitzkysaurid megalosauroid about 6 m (20 ft) in length. | |||
T. tanneri [65] |
Colorado, Utah and Wyoming, Brushy Basin member [67] [65] [60] |
"Partial skeletons of at least [three] individuals." [140] |
A large, robust megalosaurid reaching lengths of up to 11 m (35 ft). One of the largest carnivores of the formation. |
Genus | Species | Locality | Material | Notes | Images |
---|---|---|---|---|---|
C. dentisulcatus [65] |
Utah [65] |
"Partial skull, vertebrae, [and] limb elements." [141] |
Large ceratosaurs grew to lengths of about 6–7 meters (20–23 ft.) in length with large nasal horns on their snouts as well as two smaller horns above the eyes. |
||
C. magnicornis [67] |
Colorado [67] |
"Skull [and] assorted postcrania." [141] | |||
C. nasicornis [67] |
Remains of "5 individuals, including [a] nearly complete adult skeleton and subadult skeleton." [141] | ||||
Indeterminate. [60] |
Wyoming [60] |
||||
Indeterminate. [67] |
Colorado [67] |
Previously referred to Elaphrosaurus, [142] [143] [144] these remains are probably not referable to that genus and are best considered indeterminate beyond Ceratosauria. [145] | |||
Intermediate [67] |
Colorado [67] |
Now thought to be intermediate beyond Ceratosauria. | |||
F. churei [146] |
Wyoming [146] |
Tibia, astragalus, fibula. [146] |
A fragmentary theropod which may be a ceratosaurid. |
Many types of mammaliaform cynodonts, mostly early mammals, are known from the Morrison; almost all of them were small sized animals, though occupying a very large variety of ecological niches, from the more rodent-like multituberculates to the carnivorous eutriconodonts (including the possibly volant Triconolestes) to the anteater-like Fruitafossor. Unclassified types include the digger Fruitafossor windscheffelia. Docodonts included the common genus Docodon, represented by D. victor, D. striatus, and D. superbus, and Peraiocynodon sp. Multituberculates, a common type of early mammal, were represented by Ctenacodon serratus, C. laticeps, C. scindens, Glirodon grandis, Morrisonodon brentbaatar, Psalodon fortis, ?P. marshi, P. potens, and Zofiabaatar pulcher. Triconodonts present included Amphidon superstes, Aploconodon comoensis, Conodon gidleyi, Priacodon ferox, P. fruitaensis, P. gradaevus, P. lulli, P. robustus, Triconolestes curvicuspis, and Trioracodon bisulcus.
Tinodontids were represented by Eurylambia aequicrurius (probably Tinodon), and Tinodon bellus (including T. lepidus). Finally, two families of Dryolestoidea were present: Paurodontidae, including Comotherium richi, Euthlastus cordiformis, Paurodon valens, and Tathiodon agilis; and Dryolestidae, including Amblotherium gracilis, Dryolestes obtusus (common genus), D. priscus, D. vorax, Laolestes eminens, L. grandis, and Miccylotyrans minimus.
In 2009, a study by J. R. Foster was published which estimated the body masses of mammals from the Morrison Formation by using the ratio of dentary length to body mass of modern marsupials as a reference. Foster concludes that Docodon was the most massive mammaliaform genus of the formation at 141g and Fruitafossor was the least massive at 6g. The average Morrison mammal had a mass of 48.5g. A graph of the body mass distribution of Morrison mammal genera produced a right-skewed curve, meaning that there were more low-mass genera. [147]
Name | Species | Locality | Material | Notes |
---|---|---|---|---|
E. aequicrurius |
Wyoming |
A tinodontid similar in appearance to Tinodon. | ||
T. bellus |
Wyoming |
|||
T. lepidus |
Wyoming |
Name | Species | Locality | Material | Notes |
---|---|---|---|---|
A. superstes |
Wyoming |
A small amphidontid. | ||
A. comoensis |
Wyoming |
|||
C. gidleyi |
Wyoming, Brushy Basin member |
A mandible. |
An amphilestid eutriconodont slightly larger in size than Aploconodon. | |
P. gidleyi |
Wyoming |
|||
T. curvicuspis |
Utah |
|||
T. bisulcus |
Wyoming |
A triconodontid eutriconodont similar to Priacodon. |
Name | Species | Locality | Material | Notes |
---|---|---|---|---|
C. laticeps |
Wyoming |
|||
C. scindens |
||||
C. serratus |
Wyoming |
|||
G. grandis |
Colorado and Utah |
|||
M. brentbaatar |
Wyoming |
|||
P. ferox |
Wyoming |
|||
P. fruitaensis |
Colorado |
|||
P. grandaevus |
Wyoming |
|||
P. lulli |
Wyoming |
|||
P. robustus |
Wyoming |
|||
P. fortis |
||||
P. marshi |
||||
P. potens |
||||
Z. pulcher |
Wyoming |
Name | Species | Locality | Material | Notes | Images |
---|---|---|---|---|---|
C. ciscoensis [148] |
Utah, Brushy Basin Member |
||||
D. victor [149] |
|||||
F. windscheffeli |
Colorado |
Name | Species | Locality | Material | Notes |
---|---|---|---|---|
A. gracilis |
Colorado |
A small Dryolestid dryolestoid. | ||
A. megistodon [150] |
Wyoming |
|||
A. intermissus |
Utah and Wyoming |
A paurodontid dryolestoid, somewhat smaller than Archaeotrigon and Paurodon. Considered to be a junior synonym of Paurodon valens by Averianov and Martin (2015). [151] | ||
A. brevimaxillus |
Wyoming |
Paurodontid dryolestoids similar in appearance to Paurodon. Both species were considered to be junior synonyms of Paurodon valens by Averianov and Martin (2015). [151] | ||
A. distagmus |
||||
C. richi |
Wyoming |
|||
D. obtusus |
||||
D. priscus |
Wyoming |
|||
D. tenax |
||||
E. cordiformis |
Wyoming |
|||
F. atrox |
Wyoming |
A paurodontid dryolestoid similar in size to Paurodon. Considered to be a junior synonym of Paurodon valens by Averianov and Martin (2015). [151] | ||
H. |
||||
K. |
Colorado |
|||
L. eminens |
Common Dryolestid dryolestoids. | |||
L. grandis |
||||
M. |
||||
M. |
||||
M. minimus |
||||
P. valens |
Wyoming |
|||
P. dubius |
Wyoming |
A paurodontid dryolestoid. Considered to be a junior synonym of Paurodon valens by Averianov and Martin (2015). [151] | ||
T. agilis |
Wyoming |
Genus | Species | State | Member | Material | Notes | Images |
---|---|---|---|---|---|---|
|
Morrison Anomoepus lack the handprint impressions found associated with earlier instances of the ichnogenus in New England. [57] |
|||||
|
|
Multiple Dinehichnus trackways have been discovered. The tracks run parallel to one another, indicating that the trackmaker was at least somewhat of a social animal. [57] |
Dinehichnus are attributed to dryosaurids. The tracks preserve feet characterized by widely splayed toes and that are rotated somewhat toward the midline of the trackmaker's body. Each track is accompanied by "distinct ... heel impressions". [57] |
|||
P. coloradensis [152] |
|
|
Eggshell present in great abundance at the so-called "Young Egg Locality" which seems to have been a dinosaur nesting ground. [152] Congeneric eggshell fossils are found at additional Colorado sites including the Fruita Paleontological Area, the Uravan Locality and Garden Park. [152] |
P. coloradensis is described by John Foster as being "of the prismatic basic type," [152] with subspherical eggs about 10 cm (4 inches) in diameter. [153] This oospecies has been attributed to "hypsilophodontid" dinosaurs, although a lack of associated embryo material currently makes confirming the egg-layer's identity impossible. [152] |
||
|
Stegopodus represent only a portion of the Morrison's stegosaur tracks, which are already rare and generally only preserve the animal's hind feet. [58] |
Stegosaur tracks which record front feet with five digits and hind feet with three weight-bearing digits. [58] The general morphology of the tracks fit scientific predictions made eight years in advance of the erection of Stegopodus. [58] |
||||
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Category:Morrison fauna| 01]] Category:Morrison Formation|.]] Category:Late Jurassic animals of North America|.]] Category:Fauna of the Western United States|Morrison Paleobiota]] Category:Jurassic fossil record|L]] Category:Lists of prehistoric animals|Morrison Formation]] Category:Kimmeridgian life|L]] Category:Tithonian life|L]] Category:Kimmeridgian genera|L]] Category:Tithonian genera|L]] Category:Prehistoric fauna by locality|Morrison Formation]] Category:Jurassic Colorado|Morrison Paleobiota]] Category:Jurassic geology of Utah|Morrison Paleobiota]] Category:Jurassic geology of Wyoming|Morrison Paleobiota]]
/info/en/?search=User:TimTheDragonRider/sandbox1
/info/en/?search=User:TimTheDragonRider/sandbox2
/info/en/?search=User:TimTheDragonRider/sandbox:Opisthiamimus
/info/en/?search=User:The_Morrison_Man/sandbox3
The Morrison Formation is a distinctive sequence of Late Jurassic sedimentary rock that is found in the western United States. It has a vast fossil record, with a wide assortment of taxa represented, including famous dinosaurs like Brachiosaurus, Allosaurus, Diplodocus and Stegosaurus. It is composed of mudstone, sandstone, siltstone and limestone and is light grey, greenish gray, or red in colour. Most of the fossils occur in the green siltstone beds and lower sandstones, relics of the rivers and floodplains of the Jurassic period.
The formation is split into three main members, these are the Salt Wash, Tidwell and Brushy Basin members. Other subdivisions exist in specific areas of the formation, like the Bluff Sandstone Member in the Four Corners region. The most well-studied of these are the Brushy Basin and contemporaneous members, from which most of the iconic Morrison Formation fauna hails.
The rocks of the Morrison Formation were deposited on top of those of the Sundance, Swift, Ralston Creek and Summerville formations, as the Sundance Sea receded to the north and the region became a vast floodplain, fed by rivers coming in from the south and west. Multiple formations also overlie the Morrison, including the ...
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Genus | Species | Locality | Material | Notes |
---|---|---|---|---|
E. pecki |
Colorado |
Hundreds of specimens at the least |
A genus of freshwater algae in the family Clavatoraceae. | |
E. spinosa | ||||
A. bransonii |
Colorado and Wyoming |
Hundreds of specimens at the least |
A genus of freshwater algae within the family Characeae. | |
A. complanata | ||||
A. jonesii | ||||
A. latisulcata | ||||
A. obovata | ||||
A. rotunda | ||||
C. verticillata |
||||
C. voluta | ||||
L. bellatula |
||||
L. collina | ||||
L. concinna | ||||
L. latitruncata | ||||
L. aff. mensinki | ||||
L. spherica | ||||
M. voluta |
||||
O. oblata |
||||
P. verticillata |
||||
P. glypta | ||||
P. voluta |
||||
P. symmetrica | ||||
P. arguta |
||||
P. fusca | ||||
P. kimmeridgensis | ||||
P. minima collina | ||||
S. verticillata |
||||
S. obovata |
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Genus | Species | Locality | Material | Notes |
---|---|---|---|---|
M. sp. |
To be added |
A genus of Marchantiopsid liverwort. | ||
T. sp. |
A genus of liverwort belonging to the order Metzgeriales . |
Genus | Species | Locality | Material | Notes |
---|---|---|---|---|
E. laterale [2] E. bakkeri [3] E. comoensis [3] E. lyelli [2] E. cf. laterale [4] |
Wyoming, Colorado and Utah, Brushy Basin, Lake Como and Temple Canyon Members |
Silicified casts with epidermal features, stem fragments and macrofossil fragments. |
A genus of Equisetacean horsetail. | |
N. sp. |
Genus | Species | State | Member | Material | Notes |
---|---|---|---|---|---|
H. fisheri |
|
|
To be added |
A genus of Dipteridacean fern. | |
C. hymenophylloides |
|||||
O. lemonii |
|||||
A. wadei |
|||||
C. alberta C. heterophylla C. virginiensis |
|||||
G.? sp. A. G.? sp. B. |
|||||
A. montanensis |
incertae sedis | ||||
S. leithii S. medlynii |
incertae sedis | ||||
Indeterminate |
incertae sedis |
Genus | Species | State | Member | Material | Notes |
---|---|---|---|---|---|
S. elliptica |
|
|
To be added |
A genus of Caytoniale. |
Genus | Species | State | Member | Material | Notes |
---|---|---|---|---|---|
C. sp. |
|
|
To be added |
A genus of Cycad with uncertain affinities. | |
J. redmondi |
A genus of Cycad with uncertain affinities. | ||||
N. nigricollensis N. schaumburgensis N. cf. compta |
A genus of Cycad with uncertain affinities. |
Genus | Species | State | Member | Material | Notes |
---|---|---|---|---|---|
Z. arcticus |
|
|
To be added |
To be added | |
O. sp. |
|
|
|
| |
C. spp. |
|
|
|
| |
W. sp. |
|
|
|
| |
A. sp. |
|
|
|
| |
P. lindstromi P. arcticum P. spp. |
|
|
|
| |
C. wyomingensis C. spp. |
|
|
|
| |
C. sp. |
|
|
|
| |
J. redmondi |
|
|
|
| |
C. montanese |
|
|
|
|
Genus | Species | State | Member | Material | Notes |
---|---|---|---|---|---|
G. cascandensis |
|
|
To be added |
To be added | |
G. pluripartita G. sp. |
|
|
|
Genus | Species | State | Member | Material | Notes |
---|---|---|---|---|---|
C. turneri C. sp. |
|
|
To be added |
To be added |
Genus | Species | Locality | Material | Notes |
---|---|---|---|---|
B. hoodiorum |
Colorado and Utah (Brushy Basin Member) |
More than 300 specimens, three dimensional calcitic casts of a two-seeded compound cone |
Tentatively assigned as a gnetale, with some attributes of the cones pointing towards a close relation with the extant genus Ephedra. | |
D. tetragona |
Henry Mountains of Utah (Brushy Basin Member) |
"Three-dimensional casts and partially permineralized small cones". |
A gnetale with close affinities to Cretaceous and modern genera. |
Genus | Species | State | Member | Material | Notes |
---|---|---|---|---|---|
H. axelrodi |
|
|
To be added |
To be added | |
S. sp. |
|
|
To be added |
To be added | |
T. indet. |
|
|
To be added |
To be added | |
B. rechtenii B. chaneyi B. morrisonense B. spp. |
|
|
To be added |
To be added | |
C. spp. |
|
|
To be added |
To be added | |
P. medlynii |
|
|
To be added |
To be added | |
A. obscurum |
|
|
To be added |
To be added | |
A. hoodi |
|
|
To be added |
To be added | |
P. lanceolatus |
|
|
To be added |
To be added | |
X. morrisonense X. mooreii |
|
|
To be added |
To be added | |
P. resiniferous |
|
|
To be added |
To be added | |
M. obscurum M. carterii |
|
|
To be added |
To be added | |
P. sp. |
|
|
To be added |
To be added | |
P. lindstromii |
|
|
To be added |
To be added | |
S. sp. |
|
|
To be added |
To be added | |
E. sp. |
|
|
To be added |
To be added | |
P. sp. |
|
|
To be added |
To be added | |
B. provoensis B. joannei B. bassii B. scottii |
|
|
To be added |
To be added | |
C. sp. |
|
|
To be added |
To be added | |
S. radiatus |
|
|
To be added |
To be added |
Genus | Species | State | Member | Material | Notes |
---|---|---|---|---|---|
H. kirkbyorum H. taylorii H. glismannii H. owensii |
|
|
To be added |
To be added |
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Name | Species | Locality | Material | Notes |
---|---|---|---|---|
Eospongilla [7] | E. morrisonensis |
Colorado |
Two micritic body fossils with calcite-replaced megascleres | A sponge belonging to the class Demospongiae. |
Name | Species | Locality | Material | Notes |
---|---|---|---|---|
U. baileyi |
A genus of medium-sized freshwater mussels in the family Unionidae (river mussels). |
|||
U. felchi |
||||
U. iroides |
||||
U. knighti |
||||
U. lapilloides |
||||
U. macropisthus |
||||
U. mammillaris |
||||
U. nucalis |
||||
U. stewardi |
||||
U. s. utahensis |
||||
U. toxonotus |
||||
U. willistoni |
||||
V. faberi |
||||
V. mayoworthensis |
||||
V. whitei |
||||
H. jurassicus |
||||
H. lateralis |
||||
H. trigonus |
Name | Species | Locality | Material | Notes |
---|---|---|---|---|
M. morrisonensis |
||||
A. cyclostoma A. scabrida A. s. leesi A. ? reesidei |
||||
V. morrisonensis V. reesidei |
||||
L. jurassicus |
||||
R. gilloides R. jurassica |
||||
L. jurassica |
||||
T. jurassica |
||||
"P." altispiratum |
||||
A. gilloides A. jurassica |
||||
L. jurassica |
||||
L. ativuncula L. consortis L. morrisonensis |
||||
G. veternus |
Name | Species | Locality | Material | Notes |
---|---|---|---|---|
C. cf. tendaguruensis |
||||
E. sp. |
||||
L. tendagurensis |
||||
L. sp. A. |
||||
L. sp. B. |
||||
N. krasinetzi |
||||
D. acuminata |
||||
D. cf. dakotensis |
||||
C. atlantosaurica |
||||
C. marshi |
||||
Simplus |
||||
C. purbeckensis |
||||
C. coloradensis |
||||
C. morrisonensis |
||||
B. pahasapiens |
||||
B. pustulosa |
||||
M. bradyi |
||||
M. minnekahtensis |
||||
M. whitei |
||||
G. sp. |
||||
H. petersoni |
||||
H. prima |
||||
H. turneri |
||||
T. guimarotensis |
||||
D. pustulosa |
||||
T. wyomingense |
||||
C. acuticyatha |
||||
R. jurassica |
||||
C. armata |
This genus is of uncertain placement. | |||
C. striata |
||||
C. sp. |
||||
T. aff. rothi |
Genus is of uncertain placement. | |||
cf. Cambaridae indet. |
Name | Species | Locality | Material | Notes |
---|---|---|---|---|
E. ekdalei |
Utah, Brushy Basin member |
Nests produced by social insects. [8] |
||
Morrisonnepa [9] | M. jurassica |
Utah |
A hemipteran belonging to the group Nepomorpha. | |
Parapleurites [10] | P. morrisonensis |
Colorado |
a forewing. | A Locustopsid orthopteran |
T. kollaspilus |
Colorado, Brushy Basin member |
Five specimens were reported in the original description of the ichnogenus. |
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Although the paleoclimate of the Morrison formation was semiarid with only seasonal rainfall, there were enough bodies of water to support a diverse ichthyofauna. [11] Although abundant, fish remains are constrained to only certain locations within the formation, with microvertebrate sites in Wyoming especially being dominated by fish remains. [11] Indeterminate remains of ray-finned fish have been recovered from Ninemile Hill and a microvertebrate site in the Black Hills. [11] Morrison actinopterygians have been found in stratigraphic zones 2, 4, and 5, and generally have no close modern relatives. [11] The Wyoming microvertebrate remains are extracted from the sediment by screenwashing. [11] Paleoniscoid remains are geographically present in the western part of Colorado, where remains have been recovered from "a level above the Mygatt-Moore Quarry." [11] Largely complete remains of small individuals have been consistently recovered for over 15 years. [11] So far, Morrison pycnodontoids are represented by a single specimen from Dinosaur National Monument in Utah. [12] Found in stratigraphic zone 4. [13] Only a single specimen from Dinosaur National Monument in Utah has been recovered. [12] Pycnodontoids were "deep-bodied and laterally compressed fish" whose tooth morphology suggest that they preyed on small contemporary invertebrates. They may have resembled modern butterfly fish. [12] A single tooth is the only known remains. [12] Dipnoan remains found at a fossil site not far from Cañon City, Colorado. [11] Remains usually in a state of rather complete preservation. [11] Halecostome remains are geographically present in the western part of Colorado, where remains have been recovered from "a level above the Mygatt-Moore Quarry." [11] Largely complete remains of small individuals have been consistently recovered for over 15 years. [11] Amiid remains found in stratigraphic zones 2, 3, and 4. [13] Found at a fossil site not far from Cañon City, Colorado. [11] Remains usually in a state of rather complete preservation. [11]
Name | Species | Locality | Material | Notes | Images |
---|---|---|---|---|---|
C. fossanovum [11] |
A lungfish genus whose members ranged from 1 to 2 m in length and weights of up to 79 pounds, with most Morrison lungfish being on the smaller end of that range. [11] These species are believed to have had similar diets to extant lungfish like the physically similar modern genus Neoceratodus. [11] |
||||
C. ?frazieri [11] |
|||||
C. guentheri [11] |
|||||
C. robustus [11] |
|||||
Indeterminate. |
Brushy Basin and Saltwash members |
Represented by tooth plates. | |||
H. hawesi [15] |
Colorado |
A small fish of the division Halecostomi about 7.6 cm in length and 5g of live mass which probably preferred quiet water. Its fossils prominently preserve its thick interlocking scales. | |||
cf. Leptolepis [14] |
N/A |
Colorado [15] |
Known only from a single nearly complete skeleton found at Rabbit Valley. [16] Found in stratigraphic zone 5. [13] |
A 13 cm (5 inch) fish that was deeper bodied than its co-occurring contemporaries Morrolepis and Hulettia. [16] The Morrison cf. Leptolepis probably had a live mass of about 37g. [16] It is the only teleost fish known from the formation and was morphologically more highly derived than other Morrison fish. [16] It is believed to have fed on contemporary fish and small invertebrates. [16] | |
M. schaefferi [17] |
Colorado |
A coccolepid " palaeoniscoid" with forward-set eyes positioned past the front end of the lower jaw. It had a tall dorsal fin set far back on the body and an asymmetrical caudal fin. [17] Adult specimens would reach about 20 cm in length and 113 g (4 oz) in mass. [17] | |||
P. guentheri |
Colorado |
Once thought to be a species of Ceratodus. |
Frogs are known from several sites in the Morrison Formation, but are not particularly well represented. [18] The history of Morrison anuran discoveries began with the recovery of remains from Quarry 9 near Como Bluff, Wyoming. The new genus Eobatrachus was erected for some of these remains by O. C. Marsh, but the material was later considered non-diagnostic. Decades later another dubious anuran genus, Comobatrachus, was erected based on additional fragmentary remains. Despite the erection of multiple new names, only two frog species are currently recognised from the Morrison: Enneabatrachus hechti [19] and Rhadinosteus parvus. [20]
In addition to formally named taxa, indeterminate anuran remains have been recovered from Morrison strata in Colorado, Wyoming, and Utah, with the best specimens found in Dinosaur National Monument and Quarry 9. [18] Stratigraphically speaking, indeterminate anurans have been found in stratigraphic zones 2 and 4. [13] Indeterminate anurans with remains diagnostic down to the family level have also been reported from the Morrison, with pelobatids being represented by the illium of an unnamed and indeterminate species, which was recovered from Quarry 9. [21] Pelobatids are present in stratigraphic zones 5 and 6. [13]
Indeterminate salamander remains are present in stratigraphic zones 2, 4, and 5. [13] A distinctive type of salamander known only as Caudata B is present in stratigraphic zone 6. [13]
Name | Species | Locality | Material | Notes |
---|---|---|---|---|
C. aenigmaticus |
Wyoming, Brushy Basin member [18] |
A partial right humerus. [22] |
A dubious genus of prehistoric frog erected by O. C. Marsh to house fragmentary remains recovered from Reed's Quarry 9 near Como Bluff Wyoming. [18] Along with Eobatrachus it was among the earliest frog remains from the formation, although the two dubious genera were erected decades apart. [18] | |
C. marshi [23] |
Wyoming, Brushy Basin member [23] |
Represented by a single femur. [23] |
Considered a nomen dubium because the name is based on non-distinctive remains which cannot be classified in detail. [23] | |
E. hechti [19] |
A small discoglossid frog whose live weight would have only been a few grams. [19] | |||
E. agilis |
Wyoming, Brushy Basin member [18] |
A partial right humerus. [22] |
A dubious genus of prehistoric frog erected by O. C. Marsh to house fragmentary remains recovered from Reed's Quarry 9 near Como Bluff Wyoming. [18] Along with Comobatrachus it was among the earliest frog remains from the formation, although the two dubious genera were erected decades apart. [18] | |
I. hechti |
A partial skull and incomplete postcranial skeleton. [25] |
A basal salamandroid closely related to today's advanced salamanders. | ||
R. parvus [20] |
Utah |
Known from several slabs of rock which contain multiple partial specimens in association. [20] |
A pipoid and possible rhinophrynid, Rhadinosteus parvus was only about 42 mm (1.6 inches) long in life. [20] | |
Anura? | Indeterminate | Dinosaur National Monument, Colorado/Utah and Quarry 9, Wyoming. | multiple specimens? | (see text) |
Pelobatidae? | Indeterminate | Stratigraphic zones 5 and 6 | (see text) | |
Pelobatidae? | Indeterminate | Quarry 9, Wyoming | an illium | (see text) |
Caudata? | Indeterminate | Stratigraphic zones 2, 4 and 5 | (see text) | |
Caudata? | "B." | Stratigraphic zone 6 | (see text) |
Name | Species | Locality | Material | Notes | Images |
---|---|---|---|---|---|
E. robustus |
Colorado |
Several fragmentary skull, mandible, and tooth elements. |
A herbivorous eilenodontine of relatively large size. |
||
O. rarus |
Colorado, Utah and Wyoming, Brushy Basin member |
Several skulls and partial skeletons. |
A sphenodontian similar in appearance to the modern Tuatara |
||
O. gregori |
Northern Wyoming, possibly west-central Colorado. Brushy Basin Member |
Most of the skull and postcranium |
A small-bodied eusphenodontian, and one of the most complete rhynchocephalian taxa yet known from North America. |
||
T. antiquus |
Wyoming, Brushy Basin member |
A mandible. |
A small sphenodontian. |
||
Sphenodontia [26] | Indeterminate | Dinosaur National Monument | A crushed partial skull (DINO 16454) | The specimen is undescribed. Although previously considered to have belonged to Opisthias or Theretairus, recent studies have doubted this referral, thus placing it as an indeterminate sphenodont. [26] |
Numerous squamate remains have been found in the sediments of the Morrison Formation, most commonly at sites in Utah, Colorado and Wyoming. A number of taxa have been described, coming from three different groups: anguimorph and scincomorph lizards and early snakes. [27] [28] [29] The first squamates to be reported from the Morrison Formation were Paramacellodus and Dorsetisaurus, which were described from Wyoming's Quarry 9 by Don Prothero and Richard Estes. [27] Later remains would include Diablophis, originally described as a species of Parviraptor by Susan Evans in 1996 [30] but subsequently moved to the new genus Diablophis by Michael Caldwell et al. in 2015, with extra material also being reported from Utah's Cisco Mammal Quarry, and Schillerosaurus, originally described as "Schilleria" and reported from Dinosaur National Monument by Evans and Dan Chure in 1999. [31] Two later additions to the Morrison's squamate assemblages are Eoscincus and Microteras, two scincomorph lizards found at Dinosaur National Monument and Como Bluff's Quarry 9, respectively. They were described by Chase Brownstein et al. in 2022. [28] Indeterminate squamate remains have currently been described from Dinosaur National Monument. [31]
The majority of modern-day scincomorph lizards are small insectivores that feed on a range of invertebrates. [32] It is thought that their counterparts from the Morrison Formation would have occupied a similar niche due to their morphological similarities. Anguimorph lizards most likely hunted small vertebrates, and Diablophis is thought to have done so too. Prey items would have included the other squamates from the formation as well as its large diversity of small mammals. All squamates might have been prey for the larger predators of the Morrison Formation, including the abundant theropod dinosaurs and crocodilians.
Name | Species | Locality | Material | Notes |
---|---|---|---|---|
D. gilmorei |
Fruita Palaeontological Area, Colorado and Cisco Mammal Quarry, Utah (Brushy Basin Member) |
A broken right maxilla, broken right mandible and broken right dentary. Broken axis vertebrae, precloacal vertebrae, one caudal vertebra and a possible sacral vertebra have also been found. [29] |
A basal snake. [29] Originally described as a species of Parviraptor, [14] subsequently moved to its own genus. [29] | |
D. sp. |
Quarry 9 at Como Bluff, Wyoming, Utah and Colorado (Brushy Basin Member) |
An anguimorph lizard. | ||
E. ornatus |
Site 412 at Dinosaur National Monument, Utah (Brushy Basin Member) |
The holotype specimen, DINO 14864, includes a complete rostrum and palate, a partial skull roof, and both mandibles. |
A scincomorph lizard. | |
Helioscopos [33] | H. dickersonae | Site 317 at Dinosaur National Monument, Utah (Brushy Basin Member) | The holotype specimen, DINO 15914, consists of a partial skull and mandibles, lacking the anterior snout. | A stem- gecko. |
M. borealis |
Quarry 9 at Como Bluff, Wyoming (Brushy Basin Member) |
The holotype specimen, YPM VP 4718, consists of an associated maxilla and braincase. |
A scincomorph lizard. | |
P. sp. |
Fruita Palaeontological Area & Rainbow Park, Colorado and Quarry 9 at Como Bluff, Wyoming (Brushy Basin Member) |
Several jaws, two skulls, isolated jaw elements, osteoscutes and a small block bearing the posterior trunk vertebrae and hind limbs with a few ventral osteoscutes. Possibly a left prefrontal and postcranial material consisting of a scapulocoracoid, a trunk vertebra and multiple articulated bones consisting of a partial pelvis, seven caudal vertebrae and a nearly complete left hind limb. [27] [31] |
A small scincomorph lizard with blunt teeth. | |
S. sp |
Fruita Palaeontological Area, Colorado (Brushy Basin Member) |
A scincomorph lizard whose remains have been found in Middle Jurassic strata in England and Scotland as well as Late Jurassic strata in Portugal in addition to the Morrison formation remains. [34] | ||
Dinosaur National Monument, Utah (Brushy Basin Member) |
Part and counterpart of a partial dissociated skeleton and a few limb bone fragments. [31] |
A small scincomorph lizard of otherwise uncertain evolutionary affinities. [36] It is the only lizard genus endemic to the Morrison Formation. [36] | ||
Indeterminate |
Dinosaur National Monument, Utah (Brushy Basin Member) |
Specimen DNM 14720, a disarticulated skeleton and DNM 14734, a fragmentary skeleton. [37] |
Squamates of uncertain affinities. Noted as distinct from Paramacellodus and Dorsetisaurus, of which remains have been found in the same quarry. [31] |
Turtles ( Testudines) are very common fossils in the Morrison, due to their bony shells. The most common were Glyptops plicatus (very common) and Dinochelys whitei (also common, but not as common as Glyptops). Also present were Dorsetochelys buzzops and Uluops uluops.
Name | Species | Locality | Material | Notes |
---|---|---|---|---|
Colorado and Utah, Salt Wash member |
||||
C. plicatulus |
Colorado |
|||
D. whitei [38] |
Colorado, Utah and Wyoming, Brushy Basin member [38] |
Several shells and some postcranial material. [38] |
||
D. buzzops |
||||
G. plicatulus [38] |
Colorado and Wyoming, Brushy Basin member [38] |
Several shells, skulls, and partial skeletons. [38] |
||
G. ornatus [39] |
Synonym of Glyptops plicatulus. [38] | |||
G. utahensis [40] |
A complete shell. [40] |
Synonym of Glyptops plicatulus. [38] | ||
U. uluops |
Como Bluff, Wyoming, Brushy Basin member [41] |
A cranium. [41] |
Most basal Pleurosternid from the Morrison Formation. [41] |
Name | Species | Locality | Material | Notes |
---|---|---|---|---|
C. antiquus |
Colorado, Oklahoma, South Dakota, Utah and Wyoming |
A champsosaur about 25 to 50 cm in length. |
Crocodiles of a variety of sizes and habitats were common Morrison animals. Cursorial mesosuchians, or small terrestrial running crocs, included Hallopus victor and Fruitachampsa callisoni. More derived crocodilians included Diplosaurus ferox, Amphicotylus, Hoplosuchus kayi, and Macelognathus vagans.
Name | Species | Locality | Material | Notes | Images |
---|---|---|---|---|---|
A. gilmorei |
Wyoming |
||||
A. lucasii |
Colorado |
||||
A. milesi |
Wyoming, Brushy Basin member [43] |
A nearly complete skeleton. [43] |
|||
A. stovalli |
Oklahoma |
||||
D. felix |
Colorado |
||||
E. delfsi |
Colorado and Wyoming |
||||
F. callisoni |
Colorado, Brushy Basin and Saltwash members |
||||
H. victor |
Colorado, Brushy Basin member [45] |
A partial skeleton including a fragmentary skull roof. [45] |
|||
H. sanjuanensis |
Colorado and Utah |
||||
H. sp. |
Utah and Wyoming, Salt Wash member |
||||
H. kayi |
Arizona and Utah |
||||
M. vagans |
Colorado and Wyoming, Brushy Basin member [46] |
A partial left mandible (type) and several fragmentary referred fossils. [46] |
|||
T. morrisonensis |
Wyoming |
A nearly complete left mandible missing teeth. |
Pterosaurs are very uncommon fossils in the Morrison, because the fragility of their thin walled bones often prevented their remains from being preserved. [48] Despite being uncommon they are geographically widespread; [49] indeterminate pterosaur remains have been found in stratigraphic zones 2 and 4-6. [13] In addition to indeterminate remains, several species have been identified from both the rhamphorhynchoids (long-tailed pterosaurs) and pterodactyloids (short-tailed pterosaurs). [48] Since the 1970s and 80s, pterosaur finds have become more common, but are still rare. [48] Most Morrison pterosaurs have been found in marine and shoreline deposits. [48] Pterosaur tracks have been found in both the Tidwell and Saltwash members. [48] Morrison pterosaurs probably lived on fish, insects and scavenged dinosaur carcasses, or even foraged for prey, and actively hunted; [48] they are fairly ecologically diverse, ranging from small hawking insectivore Mesadactylus to the raptorial Harpactognathus. While relatively few pterosaur genera are named from the Morrison Formation, fragmentary material that is not referrable to the genus level suggests the presence of dsungaripteroids, ctenochasmatids, dimorphodontids, and more tentatively wukongopterids and pteranodontians. [50] [51] [52] [53]
Name | Species | Locality | Material | Notes | Images |
---|---|---|---|---|---|
C. ostromi |
Wyoming, Brushy Basin member |
A metacarpal. |
|||
D. montanus |
Wyoming, Brushy Basin member |
A wing phalanx. |
|||
H. gentryii |
Wyoming, Brushy Basin member |
A partial snout. |
A large rhamphorhynchid with a wingspan of about 2.5 m and live mass of about 1.5 kg (3.3 lbs). [54] Harpactognathus was related to the Solnhofen genus Scaphognathus. [54] | ||
K. insperatus |
Colorado, Brushy Basin member |
A partial postcranial skeleton. |
A large pterodactyloid with a 2.5 m (8 foot) wingspan and a live weight of about 1.5 kg (3 lbs). [55] Kepodactylus may be related to the Asian dsungaripteroid pterosaurs. [55] | ||
L. priscus |
Wyoming, Brushy Basin member |
A braincase. |
Nomen dubium initially misidentified as a bird. | ||
M. ornithosphyos |
Colorado, Brushy Basin member |
A synsacrum. | Several specimens have been incorrectly referred to Mesadactylus. [51] [52] | ||
P. saltwashensis'* |
Arizona and Oklahoma, Saltwash member |
||||
U. kateae |
Utah, Tidwell member |
A fragmentary skeleton. |
Previously thought to be an indeterminite diapsid, newer material suggests an affinity with ctenochasmatids. [53] |
The herbivorous ornithischian dinosaurs were diverse but not as common as sauropods in the Morrison. Fruitadens, previously known as the "Fruita Echinodon", was found to be a heterodontosaurid. Plate-backed stegosaurids included Hesperosaurus mjosi, Stegosaurus armatus, S. ungulatus, S. stenops, and Alcovasaurus longispinus. Armored dinosaurs that weren't stegosaurs were unknown in the formation until the 1990s. Two have been named: Gargoyleosaurus parkpinorum and Mymoorapelta maysi. Ornithopods, bipedal herbivores, came in several types. Small " hypsilophodonts" included Drinker nisti, Laosaurus celer, "L." gracilis, Nanosaurus agilis, Othnielia rex, and Othnielosaurus consors (all of which are now synonymous with Nanosaurus). Larger but similar-looking dryosaurids were represented by Dryosaurus altus and the camptosaurid Uteodon aphanoecetes, which is currently known only from Dinosaur National Monument. Still larger was the more common Camptosaurus dispar. Dryosaurids and camptosaurids were early iguanodonts, a group that would later spawn the duck-billed dinosaurs.
Morrison ornithopod trace fossils are represented by three toed tracks which are generally small. [57] The toes of Morrison ornithopod tracks are usually more widely splayed than the theropod tracks preserved in the formation. [57] Stegosaur tracks were first recognized in 1996 from a hindprint-only trackway discovered at the Clevland-Lloyd quarry, which is located near Price, Utah. [58] Two years later, a new ichnogenus called Stegopodus was erected for another set of stegosaur tracks which were found near Arches National Park, also in Utah. [58] Unlike the first, this trackway preserved traces of the forefeet. Fossil remains indicate that stegosaurs have five digits on the forefeet and three weight-bearing digits on the hind feet. [58] From this, scientists were able to successfully predict the appearance of stegosaur tracks in 1990, six years in advance of the first actual discovery of Morrison stegosaur tracks. [58] Since the erection of Stegopodus, more trackways have been found, however none have preserved traces of the front feet, and stegosaur traces remain rare. [58]
Genus | Species | State | Member | Material | Notes | Images |
---|---|---|---|---|---|---|
C. amplus [59] |
Now known to be based on a theropod foot. [61] |
|||||
C. aphanoecetes [62] |
|
|
Reclassified as Uteodon. | |||
C. browni [63] |
Junior synonym of C. dispar. [64] | |||||
"[Twenty-five to thirty] disarticulated skull elements, some with associated postcrania, approximately [ten] partial, articulated skeletons, juvenile to adult." [69] |
A member of Camptosauridae. Junior synonyms include Camptosaurus browni, C. medius, and C. nanus. | |||||
C. medius [63] |
Junior synonym of C. dispar. [64] | |||||
C. nanus [63] |
Junior synonym of C. dispar. [64] | |||||
D. nisti [70] |
"Partial skull and postcranial skeleton." [72] |
A basal neornithischian about 2 m long, slightly smaller than Othnielosaurus. [70] Junior synonym of Nanosaurus agilis [73] | ||||
D. altus [65] |
|
The remains of many individuals have been uncovered, with some sites containing hundreds of bones from Dryosaurus of multiple age groups. [74] |
A large dryosaurid iguanodont up to 2.4 m (7.9 feet) long and 114 kg (251 lbs) in weight. It was physically similar to Othnielosaurus, although larger and with more derived teeth. [75] | |||
D. elderae [73] |
|
|
A 2 partial skeletons, one a juvenile, and 2 additional fragmentary specimens. |
A large dryosaurid iguanodont up to 2.4 m (7.9 feet) long and 114 kg (251 lbs) in weight. It was physically similar to Othnielosaurus, although larger and with more derived teeth. [75] | ||
" Laosaurus" |
L. altus |
Now known as Dryosaurus altus | ||||
L. celer |
|
Considered dubious due to fragmentary remains. | ||||
L. consors |
Now known as Othnielosaurus consors | |||||
"L. gracilis" |
Considered dubious due to fragmentary remains. | |||||
N. agilis |
|
|
A small basal Neornithischian known from dozens of individuals. [73] The holotype, YPM VP 1913, is a fragmentary skeleton from a juvenile. [73] | |||
O. rex [41] |
|
|
Based on an isolated femur. [41] |
A small neornithischian 2 m in length. Dubious; many remains historically assigned to this taxon are now place within Nanosaurus. | ||
O. consors |
A basal neornithischian about 2 m long. Junior synonym of Nanosaurus agilis [73] | |||||
T. aequifacies |
|
"Vertebrae." [77] |
||||
T. lucasanus |
|
"Vertebra." [77] | ||||
U. aphanoecetes [62] |
|
|
||||
G. parkpinorum [78] |
|
"Skull [and] partial postcranium." [79] |
A polacanthine nodosaur known from reasonably complete fossil remains. Its skull measures 29 centimeters (11 in) in length, and its total body length is an estimated 3 to 4 meters (9.8 to 13.1 ft.). It may have weighed as much as 1 tonne (2,200 lb.). [78] |
|||
H. mjosi [80] |
|
"Complete skeleton with skull, subadult." [81] Known only from a single specimen. [80] |
A stegosaurine stegosaurid that was slightly smaller and more primitive than Stegosaurus itself. H. mjosi had a broader skull and longer, lower plates. Considered by some to be a species of Stegosaurus [39] | |||
M. longispinus |
|
|
"Fragmentary postcranial skeleton, adult." [82] |
A dacentrurinae stegosaurid physically similar to Stegosaurus stenops but with much larger tail spines. [83] It is also similar to Kentrosaurus in having long dermal spikes on the caudal region. [53] The thighbone length was determined at 1082 millimeters. The longest spike was 86 centimeters long. Its point was broken and it is estimated the original length of the bone core at 985 millimeters. In 2019, the genus Alcovasaurus was considered a junior synonym of Miragaia [84] | ||
M. maysi [67] |
|
|
"Skull fragments, portions of [three] skeletons, [and] other postcrania." [85] |
Both the first ankylosaur discovered in the formation and the first known North American Jurassic ankylosaur. [86] It probably weighed 500 kg (1,102 lbs) in life. [86] | ||
S. armatus [65] |
|
|
Several caudal vertebrae and assorted fragmentary postcranial elements. [40] |
S. armatus is both the first Stegosaurus to be discovered and the type species. [87] Its type specimen is poorly preserved, incomplete, and lacks diagnostic features. [40] It has been considered dubious, with S. stenops as the neotype species for the genus. [40] | ||
S. stenops [65] |
|
"[Two] complete skeletons with skulls, [four] braincases, at least [fifty] partial postcrania, juvenile to adult." [82] |
The best known Stegosaurus species, it has shorter limbs and larger plates than S. ungulatus. [89] | |||
S. sulcatus [65] |
|
Several postcranial elements, including a possible shoulder spike. [40] |
Often considered synonymous with S. stenops, [91] it may be distinct. Potentially has a shoulder spike, otherwise unknown in Stegosaurus, despite presence in relatives. [40] | |||
S. ungulatus [65] |
|
Several partial skeletons, including a partial braincase. [40] |
S. ungulatus had longer limbs and comparatively smaller plates than the better known S. stenops. [92] Although formerly portrayed with eight tail spikes, it is now known to have had the typical four. [93] Possibly synonymous with S. stenops. [39] | |||
Indeterminate. [94] |
||||||
F. haagarorum [95] |
|
|
A partial skull and mandible with several postcranial elements. [97] |
Sauropods, the giant long-necked long-tailed four-legged herbivorous dinosaurs, are among the most common and famous Morrison fossils. A few have uncertain relationships, like "Apatosaurus" minimus (possibly a basal titanosauriform) and Haplocanthosaurus. Sauropods including Haplocanthosaurus priscus, H. delfsi, and the diplodocid Eobrontosaurus appeared in the early stages of the Morrison. The middle stages were dominated by familiar forms such as the Giraffe-like Brachiosaurus altithorax, which were uncommon, but related camarasaurids, like Camarasaurus supremus, C. grandis, C. lentus, and Cathetosaurus, were very common. Also common were long, low diplodocids, like Apatosaurus ajax, A. louisae, Brontosaurus excelsus, B. parvus, Barosaurus lentus, Diplodocus longus, D. carnegii, Galeamopus and Dyslocosaurus polyonychius.
By the late Morrison, gigantic diplodocids (or likely diplodocids) had appeared, including Diplodocus hallorum (formerly Seismosaurus), Supersaurus vivianae, Amphicoelias altus, and M. fragilimus. Smaller sauropods, such as Suuwassea emiliae from Montana, tend to be found in the northern reaches of the Morrison, near the shores of the ancient Sundance Sea, suggesting ecological niches favoring smaller body size there compared with the giants found further south. [98]
Genus | Species | Locality | Material | Notes | Images |
---|---|---|---|---|---|
H. delfsi [67] |
Colorado [67] |
Partial skeleton lacking a skull. [99] |
Small haplocanthosaurs of indeterminate classification, ranging about 14 m (46 ft) long. |
||
H. priscus [67] |
Two skulless partial skeletons. [99] | ||||
M. fragillimus [67] |
Colorado, Brushy Basin member [67] |
A single, now lost, dorsal neural arch. [100] |
Large rebbachisaurid. Based on a single lost neural arch 1.5 m (5 ft) tall. [100] | ||
D. polyonychius |
Wyoming [10] |
A fragmentary forelimb and partial hindlimbs. | Phylogenetic placement is uncertain. [10] | ||
Colorado, Brushy Basin member [67] |
"Partial skull and cervicals." [102] |
A dicraeosaurid sauropod. Originally described as "Morosaurus" agilis. [101] | |||
S. emilieae |
Montana, Brushy Basin member [103] |
A partial skull and some postcrania. [98] |
A dicraeosaurid about 15m in length. | ||
A. altus [67] |
Colorado, Brushy Basin member [67] |
2 dorsal vertebrae, femur, and a pubis. [104] |
Large diplodocids about 25 m (82 ft) in length. [105] | ||
A. ajax [67] |
Colorado, Brushy Basin member [67] |
A partial postcranial skeleton and posterior skull. [10] |
Robust and abundantly wide-spread apatosaurine diplodocids reaching lengths of up to 25 m (82 ft). [106] "A." minimus likely belongs to a separate genus. | ||
A. louisae [65] |
Colorado and Utah, Brushy Basin member [65] |
Four partial specimens, one of them including a skull. [10] Three of the specimens are from DNM, one is a mid cervical from Como Bluff. [10] | |||
"A." minimus |
Wyoming [60] |
"Sacrum and pelvis." [102] | |||
A. montanus |
Colorado, Brushy Basin member [41] |
A partial sacrum that cannot be distinguished from Camarasaurus or Apatosaurus. [43] |
Dubious neosauropod. [43] | ||
B. excelsus |
Two postcranial skeletons. [10] |
Previously considered a species of Apatosaurus as per Riggs (1903). | |||
B. parvus |
Utah and Wyoming, Brushy Basin and Salt Wash members |
Three headless skeletons. [10] |
Originally called Elosaurus. | ||
B. yahnahpin [10] |
Wyoming, Brushy Basin member |
A partial postcranial skeleton. [10] |
An apatosaurine diplodocid slightly more primitive than Apatosaurus. Formerly placed in separate genus Eobrontosaurus. | ||
B. lentus [65] |
2 partial postcranial skeletons, with possibly more specimens assignable. [10] |
A diplodocid about 24 m (79 ft) in length, similar in appearance to Diplodocus.It was the rarest sauropod in the Morrison Formation. [109] | |||
B. sp |
Wyoming, Utah and Oklahoma | ||||
D. carnegii [65] |
Known from two skulls, five partial skeletons that lack skulls and manus, and hundreds of isolated postcranial remains. [111] |
Large diplodocids reaching lengths of up to 28 m (92 ft). It was one of the most abundant sauropods in the area. [112] | |||
D. hallorum |
New Mexico, Utah and Wyoming, Brushy Basin and Salt Wash members [94] |
At least 4 partial postcranial skeletons [10] |
Once classified as Seismosaurus. [113] [114] [115] [116] | ||
D. lacustris [67] |
Colorado [67] |
Known from teeth and skull remains, the latter now referred to Camarasaurus. [10] Teeth cannot be referred beyond Flagellicaudata. [10] | |||
D. longus [65] |
Colorado [67] |
Several caudal vertebrae. [117] | |||
G. hayi |
Known from a partial skeleton and braincase. [111] | ||||
G. pabsti |
Colorado and Wyoming, Brushy Basin member |
A skull and partial postcranial skeleton, another individual known from partial skull. [10] | |||
K. siberi |
Wyoming, Salt Wash member [118] |
Skull and cervical vertebrae. [118] | |||
S. vivianae [67] |
Colorado and Wyoming |
Known from several partial postcranial skeletons. [104] |
A large diplodocid about 33–34 m 108–111 ft) in length | ||
B. altithorax [14] |
Colorado, Brushy Basin and Salt Wash members [67] |
Several partial skeletons and a partial skull. |
A large brachiosaurid about 26 m (85 ft) long. |
||
C. annae [65] |
Utah, Brushy Basin member [65] |
A dorsal vertebra. |
Camarasaurs reached an adult size of about 18 m (60 ft) in length. [119] C. annae junior synonym of C. lentus. C. lewisi was originally described as Cathetosarus lewisi and was later sunk into Camarasaurus, until being considered valid once again in 2013. C. lewisi has been considered a seperate species (Cathetosaurus), and might still be a genus distinct from Camarasaurus. [120] | ||
C. grandis [67] |
"At least 6 partial skeletons including 2 skulls, hundreds of postcranial elements." [99] | ||||
C. lentus [65] |
"5 skeletons with skulls, hundreds of postcranial elements" [99] | ||||
C. lewisi [67] |
Colorado [67] |
"Nearly complete postcranial skeleton." [99] | |||
C. supremus [67] |
At least 4 partial skeletons including partial skulls. Many possible postcranial remains from Oklahoma. [22] | ||||
Indeterminate. |
|||||
Dystrophaeus | D. viaemalae [9] |
Utah, Tidwell member [9] |
Multiple vertebrae, teeth and incomplete forelimb material. [9] | Previously recovered as a diplodocid, now recovered as a macronarian [9] Type material fragmentary, but recent rediscovery of type locality has discovered more material. [123] |
Theropod dinosaurs, the carnivorous dinosaurs, came in several different types. The less derived types, the ceratosaurs and megalosaurids, included Ceratosaurus nasicornis, C. dentisulcatus, C. magnicornis, Elaphrosaurus sp., and the megalosaur Torvosaurus tanneri (including Edmarka rex). Allosaurids included the common Allosaurus fragilis (including Epanterias amplexus), Allosaurus new species, A. lucasi, and giant Saurophaganax maximus (potentially included in Allosaurus?). Also a recently discovered dinosaur has turned out to be a new species, not Allosaurus. It's a proceratosaurid tyrannosauroid.
Indeterminate theropod remains have been recovered in Utah. Indeterminate theropod tracks have been recovered from both Utah and Arizona. [124]
Genus | Species | Locality | Material | Notes | Images |
---|---|---|---|---|---|
A. fragilis [65] |
Colorado, New Mexico, Oklahoma, South Dakota, Utah and Wyoming, Brushy Basin member [67] [94] [68] [108] [60] [125] |
"At least [three] complete skulls, many partial skulls and skull elements, many partial and complete skeletons representing at least 60 individuals." [126] It was the most common large carnivore in the area. [127] [128] [38] |
|||
A. jimmadseni [129] |
Wyoming and Utah, Brushy Basin and Salt Wash members [125] [38] |
At least 15 specimens, including several skulls. | |||
A. valens |
Colorado [45] |
Half of a proximal caudal centrum | |||
C. atrox |
Wyoming, Brushy Basin member [130] |
A fragmentary skull and assorted postcrania. [130] |
Considered a junior synonym of Allosaurus. | ||
E. amplexus |
Colorado, Brushy Basin member [25] |
Several fragmentary postcranial elements of 2 individuals, [131] possible additional remains known from Wyoming. [132] | |||
L. lucaris |
Wyoming, Brushy Basin member [45] |
A fragmentary skull and several postcranial elements. [46] [45] |
Junior synonym of A. fragilis. [45] | ||
L. ferox |
Wyoming, Brushy Basin member [45] |
A partial skull, dentaries, and fragmentary postcrania. [133] [45] |
Known from one specimen with several pathologies. Today considered a junior synonym of A. fragilis. [45] | ||
S. maximus [68] |
Several partial postcranial skeletons and fragmentary skull material. [45] [51] [125] |
Generally considered to be its own genus. Sometimes considered to be a species of Allosaurus. [134] [135] | |||
C. fragilis [65] |
"Postcranial skeleton." [136] |
A basal coelurosaurian about 2.3 m (7.5 ft) long. | |||
Indeterminate. [67] |
Colorado [67] |
||||
H. miessleri |
Wyoming |
An early troodontid. | |||
K. douglassi [65] |
Utah [65] |
A small theropod thought to be one of the oldest known troodontids. | |||
P. thomsoni [67] |
Colorado, Brushy Basin member [67] |
A distal radius | |||
O. hermanni [65] |
"Skull and associated postcranial skeleton." [136] |
A small basal coelurosaurian about 2 m (6.5 ft) long. | |||
S. clevelandi [65] |
Utah [65] |
"Illium, associated elements and pelvic cranial material. [sic]" [138] |
A possible early tyrannosauroid about 4 m (13 ft) in length. | ||
T. topwilsoni |
Utah |
A basal coelurosaurian about 3.4 m (11.3 ft) long, similar in appearance to Coelurus. | |||
E. rex [60] |
Wyoming [60] |
Junior synonym of Torvosaurus tanneri. | |||
M. bicentesimus [65] |
Partial skeleton, including part of a skull. [139] |
A medium-sized piatnitzkysaurid megalosauroid about 6 m (20 ft) in length. | |||
T. tanneri [65] |
Colorado, Utah and Wyoming, Brushy Basin member [67] [65] [60] |
"Partial skeletons of at least [three] individuals." [140] |
A large, robust megalosaurid reaching lengths of up to 11 m (35 ft). One of the largest carnivores of the formation. |
Genus | Species | Locality | Material | Notes | Images |
---|---|---|---|---|---|
C. dentisulcatus [65] |
Utah [65] |
"Partial skull, vertebrae, [and] limb elements." [141] |
Large ceratosaurs grew to lengths of about 6–7 meters (20–23 ft.) in length with large nasal horns on their snouts as well as two smaller horns above the eyes. |
||
C. magnicornis [67] |
Colorado [67] |
"Skull [and] assorted postcrania." [141] | |||
C. nasicornis [67] |
Remains of "5 individuals, including [a] nearly complete adult skeleton and subadult skeleton." [141] | ||||
Indeterminate. [60] |
Wyoming [60] |
||||
Indeterminate. [67] |
Colorado [67] |
Previously referred to Elaphrosaurus, [142] [143] [144] these remains are probably not referable to that genus and are best considered indeterminate beyond Ceratosauria. [145] | |||
Intermediate [67] |
Colorado [67] |
Now thought to be intermediate beyond Ceratosauria. | |||
F. churei [146] |
Wyoming [146] |
Tibia, astragalus, fibula. [146] |
A fragmentary theropod which may be a ceratosaurid. |
Many types of mammaliaform cynodonts, mostly early mammals, are known from the Morrison; almost all of them were small sized animals, though occupying a very large variety of ecological niches, from the more rodent-like multituberculates to the carnivorous eutriconodonts (including the possibly volant Triconolestes) to the anteater-like Fruitafossor. Unclassified types include the digger Fruitafossor windscheffelia. Docodonts included the common genus Docodon, represented by D. victor, D. striatus, and D. superbus, and Peraiocynodon sp. Multituberculates, a common type of early mammal, were represented by Ctenacodon serratus, C. laticeps, C. scindens, Glirodon grandis, Morrisonodon brentbaatar, Psalodon fortis, ?P. marshi, P. potens, and Zofiabaatar pulcher. Triconodonts present included Amphidon superstes, Aploconodon comoensis, Conodon gidleyi, Priacodon ferox, P. fruitaensis, P. gradaevus, P. lulli, P. robustus, Triconolestes curvicuspis, and Trioracodon bisulcus.
Tinodontids were represented by Eurylambia aequicrurius (probably Tinodon), and Tinodon bellus (including T. lepidus). Finally, two families of Dryolestoidea were present: Paurodontidae, including Comotherium richi, Euthlastus cordiformis, Paurodon valens, and Tathiodon agilis; and Dryolestidae, including Amblotherium gracilis, Dryolestes obtusus (common genus), D. priscus, D. vorax, Laolestes eminens, L. grandis, and Miccylotyrans minimus.
In 2009, a study by J. R. Foster was published which estimated the body masses of mammals from the Morrison Formation by using the ratio of dentary length to body mass of modern marsupials as a reference. Foster concludes that Docodon was the most massive mammaliaform genus of the formation at 141g and Fruitafossor was the least massive at 6g. The average Morrison mammal had a mass of 48.5g. A graph of the body mass distribution of Morrison mammal genera produced a right-skewed curve, meaning that there were more low-mass genera. [147]
Name | Species | Locality | Material | Notes |
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E. aequicrurius |
Wyoming |
A tinodontid similar in appearance to Tinodon. | ||
T. bellus |
Wyoming |
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T. lepidus |
Wyoming |
Name | Species | Locality | Material | Notes |
---|---|---|---|---|
A. superstes |
Wyoming |
A small amphidontid. | ||
A. comoensis |
Wyoming |
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C. gidleyi |
Wyoming, Brushy Basin member |
A mandible. |
An amphilestid eutriconodont slightly larger in size than Aploconodon. | |
P. gidleyi |
Wyoming |
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T. curvicuspis |
Utah |
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T. bisulcus |
Wyoming |
A triconodontid eutriconodont similar to Priacodon. |
Name | Species | Locality | Material | Notes |
---|---|---|---|---|
C. laticeps |
Wyoming |
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C. scindens |
||||
C. serratus |
Wyoming |
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G. grandis |
Colorado and Utah |
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M. brentbaatar |
Wyoming |
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P. ferox |
Wyoming |
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P. fruitaensis |
Colorado |
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P. grandaevus |
Wyoming |
|||
P. lulli |
Wyoming |
|||
P. robustus |
Wyoming |
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P. fortis |
||||
P. marshi |
||||
P. potens |
||||
Z. pulcher |
Wyoming |
Name | Species | Locality | Material | Notes | Images |
---|---|---|---|---|---|
C. ciscoensis [148] |
Utah, Brushy Basin Member |
||||
D. victor [149] |
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F. windscheffeli |
Colorado |
Name | Species | Locality | Material | Notes |
---|---|---|---|---|
A. gracilis |
Colorado |
A small Dryolestid dryolestoid. | ||
A. megistodon [150] |
Wyoming |
|||
A. intermissus |
Utah and Wyoming |
A paurodontid dryolestoid, somewhat smaller than Archaeotrigon and Paurodon. Considered to be a junior synonym of Paurodon valens by Averianov and Martin (2015). [151] | ||
A. brevimaxillus |
Wyoming |
Paurodontid dryolestoids similar in appearance to Paurodon. Both species were considered to be junior synonyms of Paurodon valens by Averianov and Martin (2015). [151] | ||
A. distagmus |
||||
C. richi |
Wyoming |
|||
D. obtusus |
||||
D. priscus |
Wyoming |
|||
D. tenax |
||||
E. cordiformis |
Wyoming |
|||
F. atrox |
Wyoming |
A paurodontid dryolestoid similar in size to Paurodon. Considered to be a junior synonym of Paurodon valens by Averianov and Martin (2015). [151] | ||
H. |
||||
K. |
Colorado |
|||
L. eminens |
Common Dryolestid dryolestoids. | |||
L. grandis |
||||
M. |
||||
M. |
||||
M. minimus |
||||
P. valens |
Wyoming |
|||
P. dubius |
Wyoming |
A paurodontid dryolestoid. Considered to be a junior synonym of Paurodon valens by Averianov and Martin (2015). [151] | ||
T. agilis |
Wyoming |
Genus | Species | State | Member | Material | Notes | Images |
---|---|---|---|---|---|---|
|
Morrison Anomoepus lack the handprint impressions found associated with earlier instances of the ichnogenus in New England. [57] |
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|
|
Multiple Dinehichnus trackways have been discovered. The tracks run parallel to one another, indicating that the trackmaker was at least somewhat of a social animal. [57] |
Dinehichnus are attributed to dryosaurids. The tracks preserve feet characterized by widely splayed toes and that are rotated somewhat toward the midline of the trackmaker's body. Each track is accompanied by "distinct ... heel impressions". [57] |
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P. coloradensis [152] |
|
|
Eggshell present in great abundance at the so-called "Young Egg Locality" which seems to have been a dinosaur nesting ground. [152] Congeneric eggshell fossils are found at additional Colorado sites including the Fruita Paleontological Area, the Uravan Locality and Garden Park. [152] |
P. coloradensis is described by John Foster as being "of the prismatic basic type," [152] with subspherical eggs about 10 cm (4 inches) in diameter. [153] This oospecies has been attributed to "hypsilophodontid" dinosaurs, although a lack of associated embryo material currently makes confirming the egg-layer's identity impossible. [152] |
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|
Stegopodus represent only a portion of the Morrison's stegosaur tracks, which are already rare and generally only preserve the animal's hind feet. [58] |
Stegosaur tracks which record front feet with five digits and hind feet with three weight-bearing digits. [58] The general morphology of the tracks fit scientific predictions made eight years in advance of the erection of Stegopodus. [58] |
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Category:Morrison fauna| 01]] Category:Morrison Formation|.]] Category:Late Jurassic animals of North America|.]] Category:Fauna of the Western United States|Morrison Paleobiota]] Category:Jurassic fossil record|L]] Category:Lists of prehistoric animals|Morrison Formation]] Category:Kimmeridgian life|L]] Category:Tithonian life|L]] Category:Kimmeridgian genera|L]] Category:Tithonian genera|L]] Category:Prehistoric fauna by locality|Morrison Formation]] Category:Jurassic Colorado|Morrison Paleobiota]] Category:Jurassic geology of Utah|Morrison Paleobiota]] Category:Jurassic geology of Wyoming|Morrison Paleobiota]]