Concavodontinae is an extinct

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

of prehistoric

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

s in the family Praenuculidae. Concavodontinae species lived from the middle Ordovician, Caradoc epoch through the late Ordovician Ashgill epoch.The Paleobiology Database Concavodontinae entry
accessed 19 January 2012The Paleobiology Database ''Concavodonta'' entry
accessed 19 January 2012 Concavodontinae fossils are found in Europe and South America, and species are thought to have been stationary attached to substrate in shallow infaunal marine water environments where they formed shells of an aragonite composition. The subfamily Concavodontinae was named by Teresa M. Sánchez in 1999.

Description

Concavodontinae is composed of three described genera and a total of five described species. The type genus ''

Concavodonta ''Concavodonta'' is an extinct genus of early bivalve in the extinct family Praenuculidae. The genus is one of three genera in the subfamily Concavodontinae. ''Concavodonta'' is known solely from late Ordovician, Caradoc epoch, fossils found ...

'' is composed of three species found in Bavaria, France, and Argentina. The second genus, ''

Emiliodonta ''Emiliodonta'' is an extinct genus of bivalve in the extinct family Praenuculidae. The genus is one of three genera in the subfamily Concavodontinae. ''Emiliodonta'' is known solely from late Ordovician, Caradocian epoch, fossils found in S ...

'', and third genus ''

Hemiconcavodonta ''Hemiconcavodonta'' is an extinct genus of bivalve in the extinct family Praenuculidae. The genus is one of three genera in the subfamily Concavodontinae. ''Hemiconcavodonta'' is known solely from late Ordovician, Caradoc epoch, fossils foun ...

'' are both monotypic, and known only from the

Argentine Argentines (mistakenly translated Argentineans in the past; in Spanish (masculine) or (feminine)) are people identified with the country of Argentina. This connection may be residential, legal, historical or cultural. For most Argentines, s ...

precordillera Precordillera is a Spanish geographical term for hills and mountains lying before a greater range, foothills. The term is derived from ''cordillera'' (mountain range)—literally "pre-mountain range"—and applied usually to the Andes. Some places ...

. ''Concavodonta'' is a small bivalve which was first described in 1972 by Claude Babin and Michel Melou. The structuring of the shell in ''Concavodonta'' has been noted to be anomalous. While several specimens from other taxa, such as '' Praeleda costae'' and '' Ctenodonta'' have been found with occasional concavodont teeth, they are not typical. All genera in Concavodontinae are identified by the hinge displaying chevron shaped teeth where the concavity in the chevron faces the center of the hinge and the umbo. In both ''Concavodonta'' and ''Emiliodonta'' both the anterior and posterior rows of teeth in the shell face outwards away from the umbo. In ''Hemiconcavodonta'' only the posterior teeth are concavodont, while the anterior teeth are convexodont and thus facing away from the hinges center. Concavodontinae differs from the second subfamily in Praenuculidae,

Praenuculinae Praenuculinae is an extinct subfamily of prehistoric bivalves in the family Praenuculidae. Praenuculinae species lived from the middle Ordovician through the late Devonian.

, whose members are identified by tooth chevrons with concavities facing the outer edges of the shell and chevron points facing the umbo.

References

Praenuculidae Prehistoric bivalves Prehistoric animal subfamilies Ordovician animals {{paleo-bivalve-stub