{{Short description|Extinct family of bivalves}} {{Automatic taxobox | fossil_range = Ordovician - Devonian {{Fossilrange|487|391}} | image = | image_caption = | taxon = Praenuculidae | authority = McAlester, 1969 | subdivision_ranks = Subfamilies | subdivision = ''See text'' }}
'''Praenuculidae''' is an extinct family of prehistoric bivalves in the superfamily Nuculoidea.<ref name="Carter2011">{{cite journal |last1=Carter |first1=J.G. |year=2011 |title=A Synoptical Classification of the Bivalvia (Mollusca) |journal=Paleontological Contributions |volume=4 |pages=1–47 |url=http://kuscholarworks.ku.edu/dspace/bitstream/1808/8287/3/Carter%20ms.pdf|display-authors=etal}}</ref> Praenuculidae species lived from the early Ordovician, Arenig stage through the Early Devonian Emsian stage.<ref name="PBDB">[https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=61902 The Paleobiology Database Praenuculidae entry] accessed 11 January 2012</ref> Praenuculidae fossils are found worldwide, present on every continent except Antarctica.<ref name="PBDB"/> Species in this family are thought to have been sessile, attached to the substrate in shallow infaunal marine water environments, where they formed shells of an aragonite composition. The family Praenuculidae was named by A. Lee McAlester in 1969.<ref name="PBDB"/>
==Description== Praenuculidae first emerged in the early Ordovician and diversified from around 6 genera in the early Orodvician to a maximum of thirteen genera by the Late Ordovician.<ref name="Nevesskaya2008">{{cite journal |last1=Nevesskaya |first1=L.A. |year=2008 |title=Dynamics of Taxonomic Diversity of Bivalves in the Phanerozoic |journal=Paleontological Journal |volume=42 |issue=4 |pages=335–342 |doi=10.1134/S0031030108040011|bibcode=2008PalJ...42..335N |s2cid=84204347 }}</ref> As a result of the Ordovician–Silurian extinction event the family was reduced to three genera during the Silurian and by the end of the Devonian the family was entirely extinct.<ref name="Nevesskaya2008"/> The family is composed of up to seventeen genera, most divided between the two described subfamilies erected by Teresa M. Sánchez in 1999.<ref name="Sánchez1999">{{cite journal |last1=Sánchez |first1=T.M. |year=1999 |title=New Late Ordovician (Early Caradoc) Bivalves from the Sierra de Villicum (Argentine Precordillera) |journal=Journal of Paleontology |volume=73 |issue=1 |pages=66–76 |doi=10.1017/S0022336000027554 |jstor=1306745|bibcode=1999JPal...73...66S |s2cid=133414164 }}</ref> The structure of the chevroned hinge teeth is the dominant feature by which members of Praenuculidae are divided between the two subfamilies. The majority of Praenuculidae genera possess teeth with a chevron concavity that faces towards the outer sides of the shell and a chevron point facing the umbo.<ref name="Sánchez1999"/> These genera are grouped into the larger subfamily, Praenuculinae. Three of the genera are placed into the second subfamily, Concavodontinae, based on the teeth having chevron concavities which face in the reverse, towards the center of the hinge and points facing the outside edges of the shell.<ref name="Sánchez1999"/>
In the original 1999 description of the subfamilies, ''Cardiolaria'' was not placed into a specific subfamily due to the uncertain family affinities of the genus. ''Cardiolaria'' was placed in Praenuculidae by McAlester in 1969 with the original description of the family. It was suggested by John C. Cope in 1997 that the genus may belong elsewhere in the subclass Protobranchia,<ref name="Carter2011"/> formerly called Palaeotaxodonta. Both ''Deceptrix'' and ''Cardiolaria'' are currently accepted as members of the family Cardiolariidae erected by Cope in 1997.<ref name="http://paleodb.org/cgi-bin/bridge.pl?a=checkTaxonInfo&taxon_no=213987&is_real_user=PBDBCardiolariidae">[https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=213987 The Paleobiology Database Cardiolariidae entry] accessed 5 February 2012</ref><ref name="Carter2011"/> The genus ''Eritropis'' was formerly included in the family, however it was moved to a new family, Eritropidae by John C. Cope in 2000.<ref name="Sánchez1999"/><ref name="Zong-Jie2004">{{cite journal |last1=Zong-Jie |first1=F. |last2=Cope |first2=J.C.W. |year=2004 |title=Early Ordovician bivalves from Dali, West Yunnan, China |journal=Palaeontology |volume=47 |issue=5 |pages=1121–1158 |doi=10.1111/j.0031-0239.2004.00403.x|bibcode=2004Palgy..47.1121Z |s2cid=140648734 }}</ref>
==Genera== *Concavodontinae **''Concavodonta'' **''Emiliodonta'' (syn. ''Emiliania'') **''Hemiconcavodonta'' *Praenuculinae **''Cuyopsis'' **''Fidera'' **''Ledopsis'' **''Palaeoconcha'' **''Paulinea'' **''Pensarnia'' **''Praeleda'' **''Praenucula'' (type genus) **''Trigonoconcha'' **''Similodonta'' **''Villicumia'' *''incertae sedis'' **''Pseudonucula''
A number of genera which were placed in the family have been moved to other families. They include:
*Cardiolariidae **''Cardiolaria'' (syn. ''Honeymania'') **''Deceptrix'' **''Inaequidens''
==References== {{Reflist}}
{{Taxonbar|from=Q3401210}}
Category:Praenuculidae Category:Early Ordovician first appearances Category:Ordovician bivalves Category:Silurian bivalves Category:Devonian bivalves Category:Early Devonian extinctions Category:Prehistoric bivalve families