The Posttornoceratidae are Late

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...

goniatites ''Goniatites'' is a genus of extinct cephalopods belonging to the family Goniatitidae, included in the superfamily Goniatitaceae. '' Hibernicoceras'' and '' Hypergoniatites'' are among related genera. Species Description The shell is genera ...

(

Ammonoidea Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttle ...

) included in the superfamily

Tornoceratoidea Tornoceratoidea, also known as Tornocerataceae, is a superfamily of goniatitid ammonoids included in the suborder Tornoceratina. Tornoceratoidea, or Tornocerataceae, is essentially the Cheilocerataceae of Miller, Furnish, and Schindewolf (195 ...

. The family, Posttornoceratidae, named by Bogoslovsky in 1962, is based on the genus ''Posttornoceras'', named by Wedekind in 1910, originally included in the Tornoceratidae (sensu Miller et al. 1964). The Posttornoceratidae produced subglobular to discoidal shells with small, closed umbilici and lateral lobes in the suture that are produced adventitiously (i.e. haphazardly) from the first lateral saddles.

Evolution and taxonomy

Derivation

The Posttornoceratidae are derived from the Falcitornoceratidae through ''Exotornocers'' (Saunders et al. 2004)

Taxonomic divisions

Subfamilies

The family has been split into two subfamilies each containing two genera. Slightly older are the lower to middle Famennian Posttornoceratinae, followed by the later Famennian Discoclymeniinae. The Posttornoceratinae contains ''Exotornocers'' and ''Posttornoceras'', the Discoclymeniinae, ''Discoclymenia'' and ''Alpinites''.

Genera

'' Posttornoceras'', type genus of the Posttornoceratinae was named by Wedekind in 1910. ''Posttornoceras''has a subglobular to discoidal shell with a small, closed umbilicus and biconvex growth lines (Miller et al. 1964). Sutural lobes next to the ventral lobe are formed adventitiously in the first latera saddles. ''Posttornoceras'' is derived from ''Exotornoceras'' (Saunders et al. 2004) and has been found in Upper Devonian sediments in Germany and Poland (Miller et al. ibid) '' Exotornoceras'' is the ancestral tornoceratid, named by Becker in 1993. ''Exotornoceras'' is derived from ''Gundolficeras''( Falcitornoceratinae) '' Discoclymenia'' is the type of the Discoclylemniinae, named by Hyatt in 1844. Discoclymenia has a subglobular to discoidal shell with a small, closed umbilicus, like ''Sporadoceras'' but with additional adventitious lobes in the 1st lateral saddles. ''Discoclymenia" and "Sporadoceras'' are included in the subfamily Sporadoceratinae of Miller and Furnish (1964) along with ''Praeglyphioceras'' according to Miller et at (1964) . ''Discoclymenia'' comes from the Upper Devonian of Europe and North Africa. ''

Alpinites ''Alpinites'' is a genus belonging to the Discoclymeniinae subfamily, a member of the Goniatitida order. They are an extinct group of ammonoid, which are shelled cephalopods related to squids, belemnites, octopuses, and cuttlefish, and more dist ...

'' was named by Bogolsovsky in 1971 and is derived from Discoclymenia (Saunders et al. 2004).

References

*Miller, Furnish, and Shindewolf (1964) Paleozoic Ammonoidea; in the Treatise on Invertebrate Paleontology, vol L, Mollusca Ammonoidea; GSA and University of Kansas press. L47-50. . *Saunders, Work, and Nikoleava 2004, Evolution of Complexity in Paleozoic Ammonoid Sutures, Supplementary Material. Science magazine on-lin

2-2-09
The Paleobiology Database
accessed on 02/02/09 {{Taxonbar, from=Q7234503 Posttornoceratidae, Tornoceratoidea Goniatitida families Devonian first appearances Late Devonian animals Late Devonian extinctions