Peytoia is a genus of
hurdiidradiodont, an early diverging order of stem-group
arthropods, that lived in the
Cambrian period, containing two species, Peytoia nathorsti from the
Miaolingian of Canada and Peytoia infercambriensis from Poland, dating to
Cambrian Stage 3.[1] Its two frontal appendages had long
bristle-like spines, it had no fan tail, and its short stalked eyes were behind its large head.
108 specimens of Peytoia are known from the Greater
Phyllopod bed, where they comprise 0.21% of the community.[2]
Peytoia nathorsti and its junior synonym Laggania cambria played a major role in the discovery of the radiodont body plan. Initially interpreted as a
jellyfish and a
sea cucumber respectively, they were eventually shown to be the mouthparts and body of a single animal, which bore Anomalocaris-like appendages.
Peytoia infercambriensis is the geologically oldest known radiodont species.[1]
Classification
Peytoia belongs to the clade
Hurdiidae, and is closely related to the contemporary genus Hurdia.[3]
The history of Peytoia is entangled with that of "Laggania" and Anomalocaris: all three were initially identified as isolated body parts and only later discovered to belong to one type of animal. This was due in part to their makeup of a mixture of
mineralized and unmineralized body parts; the oral cone (mouth) and frontal appendage were considerably harder and more easily
fossilized than the delicate body.[7]
The first was a detached frontal appendage of Anomalocaris, described by
Joseph Frederick Whiteaves in 1892 as a
phyllocaridcrustacean, because it resembled the abdomen of that taxon.[7] The first fossilized oral cone was discovered by
Charles Doolittle Walcott, who mistook it for a
jellyfish and placed it in the genus Peytoia. In the same paper, Walcott described a poorly-preserved body specimen as Laggania; he interpreted it as a
holothurian (sea cucumber). In 1978,
Simon Conway Morris noted that the mouthparts of Laggania were identical to Peytoia, but interpreted this as indicating that Laggania was a composite fossil of Peytoia and the sponge Corralio undulata.[8] Later, while clearing what he thought was an unrelated specimen,
Harry B. Whittington removed a layer of covering stone to discover the unequivocally connected arm thought to be a phyllocarid abdomen and the oral cone thought to be a jellyfish.[9][7] Whittington linked the two species, but it took several more years for researchers to realize that the continuously juxtaposed Peytoia, Laggania and frontal appendage represented one enormous creature.[7]Laggania and Peytoia were named in the same publication, but Conway Morris selected Peytoia as the valid name in 1978, which makes it the valid name according to
International Commission on Zoological Nomenclature rules.[8][10]
Only specimen of Peytoia infercambriensis
The discovery that Anomalocaris, Laggania, and Peytoia represented parts of a single type of animal led to the synonymization of the three genera, with Peytoia nathorsti reclassified as Anomalocaris nathorsti.[11]Peytoia nathorsti was subsequently considered a junior synonym of Anomalocaris canadensis, while Laggania cambria became recognized as a distinct genus and species again,[12] but in 2012 it was determined that Anomalocaris canadensis had an oral cone with only three large plates, unlike that of Laggania cambria and Peytoia nathorsti with four, and Peytoia was once again recognized as valid, with Laggania its junior synonym.[10]
A second species, Peytoia infercambriensis, was named in 1975 as Pomerania infercambriensis. Its discoverer, Kazimiera Lendzion, interpreted it as a member of
Leanchoiliidae,[13] a family which now known as part of the unrelated
megacheirans (great appendage arthropods). It was subsequently renamed Cassubia infercambriensis because the name Pomerania had already been used for an ammonoid.[14]C. infercambriensis was later recognized as a
radiodont.[15] It was later determined that the specimen was a composite of a radiodont frontal appendage and the body of an unknown arthropod.[1] Due to the close similarity of the appendage to Peytoia nathorsti, C. infercambriensis was reassigned to Peytoia.[1]
Description
Comparison of the frontal appendages of Peytoia with other members of Hurdiidae
Morphology and movement range of the frontal appendage of Peytoia nathorsti
P. nathorsti had body length about 28.7–30.3 cm (11.3–11.9 in).[16] The oral cone of Peytoia nathorsti has four large plates, similar to Hurdia, as compared to three in Anomalocaris. However, unlike Hurdia, the oral cone of Peytoia lacks inner rows of spines.[17] The frontal appendages have 13 podomeres in their distal part, as is typical and likely ancestral for radiodonts. Like other hurdiid radiodonts, the frontal appendages have five blade-like endites, which have short auxiliary spines. An intercalary podomere is present, separating the proximal and distal ends of the appendage. The appendages also have large medial spines, sometimes referred to as "gnathites", which face towards the opposite appendage.[18] The trunk consists of 13 segments, which are associated with wide swimming flaps. Compared to Hurdia, Peytoia has less prominent setal blades.[19]
Phylogeny
Phylogenetic position of Peytoia within Panarthropoda, according to Pates et al. (2022).[20]
It has been proposed that the frontal appendages of Peytoia were used to sift sediment for prey, however, some authors have considered this unlikely due to the small size and irregular spacing of the auxiliary spines. It has been alternatively proposed that Peytoia was a predator, using its appendages to capture slow-moving, relatively large
benthic prey.[21]
^Daley, Allison C.; Budd, Graham E.; Caron, Jean-Bernard (2013-03-22). "Morphology and systematics of the anomalocaridid arthropod Hurdia from the Middle Cambrian of British Columbia and Utah". Journal of Systematic Palaeontology. 11 (7): 743–787.
doi:
10.1080/14772019.2012.732723.
eISSN1478-0941.
ISSN1477-2019.
S2CID86465719.
^
abConway Morris, S. (1978). "Laggania cambria Walcott: A composite fossil". Journal of Paleontology. 52 (1): 126–131.
^Conway Morris, S. (1998). The crucible of creation: the Burgess Shale and the rise of animals. Oxford [Oxfordshire]: Oxford University Press. pp. 56–9.
ISBN0-19-850256-7.
^
abDaley, A. and Bergström, J. (2012). "The oral cone of Anomalocaris is not a classic 'peytoia'." Naturwissenschaften,
doi:
10.1007/s00114-012-0910-8
^Whittington, H. B.; Briggs, D. E. G. (1985-05-14). "The largest Cambrian animal, Anomalocaris, Burgess Shale, British Columbia". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 309 (1141): 569–609.
Bibcode:
1985RSPTB.309..569W.
doi:
10.1098/rstb.1985.0096.
JSTOR2396268.
Peytoia is a genus of
hurdiidradiodont, an early diverging order of stem-group
arthropods, that lived in the
Cambrian period, containing two species, Peytoia nathorsti from the
Miaolingian of Canada and Peytoia infercambriensis from Poland, dating to
Cambrian Stage 3.[1] Its two frontal appendages had long
bristle-like spines, it had no fan tail, and its short stalked eyes were behind its large head.
108 specimens of Peytoia are known from the Greater
Phyllopod bed, where they comprise 0.21% of the community.[2]
Peytoia nathorsti and its junior synonym Laggania cambria played a major role in the discovery of the radiodont body plan. Initially interpreted as a
jellyfish and a
sea cucumber respectively, they were eventually shown to be the mouthparts and body of a single animal, which bore Anomalocaris-like appendages.
Peytoia infercambriensis is the geologically oldest known radiodont species.[1]
Classification
Peytoia belongs to the clade
Hurdiidae, and is closely related to the contemporary genus Hurdia.[3]
The history of Peytoia is entangled with that of "Laggania" and Anomalocaris: all three were initially identified as isolated body parts and only later discovered to belong to one type of animal. This was due in part to their makeup of a mixture of
mineralized and unmineralized body parts; the oral cone (mouth) and frontal appendage were considerably harder and more easily
fossilized than the delicate body.[7]
The first was a detached frontal appendage of Anomalocaris, described by
Joseph Frederick Whiteaves in 1892 as a
phyllocaridcrustacean, because it resembled the abdomen of that taxon.[7] The first fossilized oral cone was discovered by
Charles Doolittle Walcott, who mistook it for a
jellyfish and placed it in the genus Peytoia. In the same paper, Walcott described a poorly-preserved body specimen as Laggania; he interpreted it as a
holothurian (sea cucumber). In 1978,
Simon Conway Morris noted that the mouthparts of Laggania were identical to Peytoia, but interpreted this as indicating that Laggania was a composite fossil of Peytoia and the sponge Corralio undulata.[8] Later, while clearing what he thought was an unrelated specimen,
Harry B. Whittington removed a layer of covering stone to discover the unequivocally connected arm thought to be a phyllocarid abdomen and the oral cone thought to be a jellyfish.[9][7] Whittington linked the two species, but it took several more years for researchers to realize that the continuously juxtaposed Peytoia, Laggania and frontal appendage represented one enormous creature.[7]Laggania and Peytoia were named in the same publication, but Conway Morris selected Peytoia as the valid name in 1978, which makes it the valid name according to
International Commission on Zoological Nomenclature rules.[8][10]
Only specimen of Peytoia infercambriensis
The discovery that Anomalocaris, Laggania, and Peytoia represented parts of a single type of animal led to the synonymization of the three genera, with Peytoia nathorsti reclassified as Anomalocaris nathorsti.[11]Peytoia nathorsti was subsequently considered a junior synonym of Anomalocaris canadensis, while Laggania cambria became recognized as a distinct genus and species again,[12] but in 2012 it was determined that Anomalocaris canadensis had an oral cone with only three large plates, unlike that of Laggania cambria and Peytoia nathorsti with four, and Peytoia was once again recognized as valid, with Laggania its junior synonym.[10]
A second species, Peytoia infercambriensis, was named in 1975 as Pomerania infercambriensis. Its discoverer, Kazimiera Lendzion, interpreted it as a member of
Leanchoiliidae,[13] a family which now known as part of the unrelated
megacheirans (great appendage arthropods). It was subsequently renamed Cassubia infercambriensis because the name Pomerania had already been used for an ammonoid.[14]C. infercambriensis was later recognized as a
radiodont.[15] It was later determined that the specimen was a composite of a radiodont frontal appendage and the body of an unknown arthropod.[1] Due to the close similarity of the appendage to Peytoia nathorsti, C. infercambriensis was reassigned to Peytoia.[1]
Description
Comparison of the frontal appendages of Peytoia with other members of Hurdiidae
Morphology and movement range of the frontal appendage of Peytoia nathorsti
P. nathorsti had body length about 28.7–30.3 cm (11.3–11.9 in).[16] The oral cone of Peytoia nathorsti has four large plates, similar to Hurdia, as compared to three in Anomalocaris. However, unlike Hurdia, the oral cone of Peytoia lacks inner rows of spines.[17] The frontal appendages have 13 podomeres in their distal part, as is typical and likely ancestral for radiodonts. Like other hurdiid radiodonts, the frontal appendages have five blade-like endites, which have short auxiliary spines. An intercalary podomere is present, separating the proximal and distal ends of the appendage. The appendages also have large medial spines, sometimes referred to as "gnathites", which face towards the opposite appendage.[18] The trunk consists of 13 segments, which are associated with wide swimming flaps. Compared to Hurdia, Peytoia has less prominent setal blades.[19]
Phylogeny
Phylogenetic position of Peytoia within Panarthropoda, according to Pates et al. (2022).[20]
It has been proposed that the frontal appendages of Peytoia were used to sift sediment for prey, however, some authors have considered this unlikely due to the small size and irregular spacing of the auxiliary spines. It has been alternatively proposed that Peytoia was a predator, using its appendages to capture slow-moving, relatively large
benthic prey.[21]
^Daley, Allison C.; Budd, Graham E.; Caron, Jean-Bernard (2013-03-22). "Morphology and systematics of the anomalocaridid arthropod Hurdia from the Middle Cambrian of British Columbia and Utah". Journal of Systematic Palaeontology. 11 (7): 743–787.
doi:
10.1080/14772019.2012.732723.
eISSN1478-0941.
ISSN1477-2019.
S2CID86465719.
^
abConway Morris, S. (1978). "Laggania cambria Walcott: A composite fossil". Journal of Paleontology. 52 (1): 126–131.
^Conway Morris, S. (1998). The crucible of creation: the Burgess Shale and the rise of animals. Oxford [Oxfordshire]: Oxford University Press. pp. 56–9.
ISBN0-19-850256-7.
^
abDaley, A. and Bergström, J. (2012). "The oral cone of Anomalocaris is not a classic 'peytoia'." Naturwissenschaften,
doi:
10.1007/s00114-012-0910-8
^Whittington, H. B.; Briggs, D. E. G. (1985-05-14). "The largest Cambrian animal, Anomalocaris, Burgess Shale, British Columbia". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 309 (1141): 569–609.
Bibcode:
1985RSPTB.309..569W.
doi:
10.1098/rstb.1985.0096.
JSTOR2396268.