Atrypid
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Atrypa Temporal range: Late Ordovician-Carboniferous ~449–336 Ma |
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| Atrypa reticularis, 26mm, Eifel, Germany | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Brachiopoda |
| Class: | Rhynchonellata |
| Order: | Spiriferida |
| Suborder: | Atripidina |
| Family: | Atrypidae |
| Genus: |
Atrypa Dalman, 1828 |
| Species | |
| Synonyms | |
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Cleiothyris Phillips, 1841, Mikrothyris |
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Cleiothyris Phillips, 1841, Mikrothyris
Atrypa is a genus of brachiopod with shells round to short egg-shaped, covered with many fine radial ridges (or costae), that split further out and growthlines perpendicular to the costae and 2-3 times wider spaced. The pedunculate valve is a little convex, but tends to level out or even become slightly concave toward the anterior margin (that is: opposite hinge and pedicle). The brachial valve is highly convex. There is no interarea (that is a flat area bordering the hinge line approximately perpendicular with the rest of the valve) in either valve. Atrypa was a cosmopolitan and occurred from the late Lower Silurian (Telychian) to the early Upper Devonian (Frasnian). Other sources expand the range from the Late Ordovician to Carboniferous, approximately from 449 to 336 Ma. A proposed new species, A. harrisi, was found in the trilobite-rich Floresta Formation in Boyacá, Colombia.
As Atrypa was erected early on, many species have been reassigned since.
In some fossil material, organic compounds may be preserved. Only the more stable amino acids tend to be preserved in very old fossils. In specimens of Atrypa reticularis from the Wenlock Shales (Lower Silurian), alanine, glycine, glutamic acid, leucine, isoleucine, proline, valine, and aspartic acid have been found.
Atrypa devoniana, pedical valve
Atrypa devoniana, brachial valve
Atrypa devoniana, anterior view
Atrypa devoniana, posterior view
Atrypa devoniana, lateral view
Atrypa sp.; Couvinian (Middle Devonian); El Pical, Leon, Spain. Eroded to show spiralia on the right.
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Wikipedia