Orthothecida Temporal range:
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Scientific classification
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Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Brachiopoda |
Class: | † Hyolitha |
Order: | †
Orthothecida Marek, 1966 |
Families | |
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The orthothecids are one of the two hyolith orders. [2]
Marek diagnoses the order thus: Conchs with a flat or concave ventral surface — opercula with large, flat cardinal processes but without clavicles – tightly sigmoidal, sediment-filled intestine – helens absent.
Sometimes the Circothecidae and Tetrathecidae are split out into a separate order 'Circothecida', which is defined by the bottom surface not being flat, the cardinal processes being pronounced, and a circular rim sometimes showing hints of differentiation into clavicles. [3]
Marek [3] gives the following diagnoses:
Kouchinsky [4] lists the following taxonomic criteria:
Elsewhere [5]: 243 is stated:
Additional genera are not assigned to a family:
Orthothecida Temporal range:
| |
---|---|
Scientific classification
![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Brachiopoda |
Class: | † Hyolitha |
Order: | †
Orthothecida Marek, 1966 |
Families | |
|
The orthothecids are one of the two hyolith orders. [2]
Marek diagnoses the order thus: Conchs with a flat or concave ventral surface — opercula with large, flat cardinal processes but without clavicles – tightly sigmoidal, sediment-filled intestine – helens absent.
Sometimes the Circothecidae and Tetrathecidae are split out into a separate order 'Circothecida', which is defined by the bottom surface not being flat, the cardinal processes being pronounced, and a circular rim sometimes showing hints of differentiation into clavicles. [3]
Marek [3] gives the following diagnoses:
Kouchinsky [4] lists the following taxonomic criteria:
Elsewhere [5]: 243 is stated:
Additional genera are not assigned to a family: