Atrypa

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).[4] Other sources expand the range from the Late Ordovician to Carboniferous, approximately from 449 to 336 Ma.[3] A proposed new species, A. harrisi, was found in the trilobite-rich Floresta Formation in Boyacá, Colombia.

Reassigned species
As Atrypa was erected early on, many species have been reassigned since.
 * A. arata = Pentamerella arata
 * A. aspera var. occidentalis = Spinatrypa occidentalis
 * A. astuta = Felinotoechia astuta
 * A. congregata = Camarotoechia congregata
 * A. coralifera = Dictyonella coralifera
 * A. depressa = Plagiorhyncha glassii
 * A. dubia = Protorhyncha dubia
 * A. elongata = Rensselaeria elongata
 * A. exigua = Protozyga exigua
 * A. extans = Triplesia extans
 * A. flabellites = Leptocoelia propria
 * A. gruenwaldtiaeformis = Nalivkinia gruenwaldtiaeformis
 * A. hemiplicata = Parastrophina hemiplicata
 * A. hemisphaerica = Eocoelia hemisphaerica
 * A. hircina = Hircinisca hircina
 * A. hirsuta = Parazyga hirsuta
 * A. hystrix var. occidentalis = Spinatrypa occidentalis
 * A. increbescens = Rhynchotrema increbescens
 * A. kolymensis = Vagrania kolymensis
 * A. laevis = Meristella laevis
 * A. lens = Stricklandia lens
 * A. linguifera = Antirhynchonella linguifera
 * A. medialis = Eatonia medialis
 * A. modesta = Zygospira modesta
 * A. nitens = Hisingerella nitens
 * A. nitida = Whitfieldella nitida
 * A. nucella = Lycophoria nucella
 * A. obovata = Glassia obovata
 * A. obtusiplicata = Pectorhyncha obtusiplicata
 * A. peculiaris = Costellirostra peculiaris
 * A. plebeia = Dicamara plebeia
 * A. pleiopleura = Pleiopleurina pleiopleura
 * A. prunum = Atrypella prunum
 * A. recurvirostra = Zygospira recurvirostra
 * A. scitula = Charionella scitula
 * A. sordida = Cyclocoelia sordida
 * A. tumida = Meristina tumida
 * A. unisulcata = Pentagonia peersii

Organic content of Atrypa fossils
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.