Paratornoceratinae is a subfamily of oxyconic dimeroceratids included in the order

Goniatitida Goniatids, informally goniatites, are Ammonoidea, ammonoid cephalopods that form the order Goniatitida, derived from the more primitive Agoniatitida during the Middle Devonian some 390 million years ago (around Eifelian stage). Goniatites (goniat ...

, a group of Paleozoic ammonoids, which have closer affinity to living

coleoids Subclass Coleoidea, or Dibranchiata, is the grouping of cephalopods containing all the various taxa popularly thought of as "soft-bodied" or "shell-less" (i.e., octopuses, squid and cuttlefish). Unlike its extant sister group, Nautiloidea, whose ...

than to '' Nautilus''. Paratornoceratinae as defined by Ebbighausen, Becker, & Bockwinkel in 2002 comprises three recognised genera with sharp, oxyconic, venters; ''

Acrimeroceras ''Acrimeroceras'' is an oxyconic Devonian goniatite and one of three genera included in the subfamily Paratornoceratinae. The others being '' Paratornoceras'' and ''Paratoceras'' or ''ex'' '' Polonites''. ''Acrimeroceras'' has a shell like ...

'', '' Paratornoceras'', and '' Polonites''. The shell, as described for the type, ''Paratornoceras'', is subglobular and evolute on young stages, but discoidal and with closed umbilicus in the adult.

References

* Ebbighausen, V., Becker, R.T. & Bockwinkel, J. (2002): Morphometric Analyses and Taxonomy of oxyconic Goniatites (Paratornoceratinae n. subfam.)... Proceedings of the Geological Survey, 57, Vienna, 2002.
The Paleobiology Database Paratornoceratinae entry
Dimeroceratidae Devonian first appearances Devonian extinctions {{Goniatitida-stub