''Pachylyroceras'' is a large, generally subglobular, Upper Mississippian gonitite and included in the cephalopod subclass

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 ...

Recognition

''Pachylyroceras'' produced a large shell that is moderately evolute to moderately involute and thickly discoidal to subglobular, with a rather wide umbilicus. Surface sculpture consists of coarse, widely spaced longitudinal lirae. Constrictions where present are wide and deep. Its suture has a narrow bifurcated ventral lobe with slightly divergent to subparallel sides and a median saddle less than half the height.

Taxonomic position

''Pachylyroceras'', named by Ruzhentsev & Bogoslovskaia (1971), is included in the Neoglyphiocerataceae, (sometimes written Neoglyphioceratoidea), but its position within the superfamily varies according to whose classification. The revised version of the Treatise, Part L (W. M. Furnish et al. 2009 ) includes ''Pachylyroceras'' as well as '' Alaoceras'', '' Caenolyroceras'', '' Dombarigloria'', and ''

Lyrogoniatites ''Lyrogoniatitites'' is a neoglyphioceratoidean ammonite, in the order Goniatitida, related to genera like '' Alaoceras'', ''Cravenoceras'', '' Dumbarigloria'' and '' Pachylyroceras''. Description ''Lyrogoniatites'' is similar to '' Neoglyphioc ...

'' in the Neoglyphioceratidae and subfamily Lyrogoniatitinae. Dieter Korn (2006) also included ''Pachyhlyroceras'' in the Lyrogoniatitinae, but in the family

Cravenoceratidae The Cravenoceratidae is one of six families included in the ammonoid superfamily Neoglyphioceratoidea, which lived during the latter part of the Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phane ...

. Saunder, Work, and Nickoleava (1999) also included Pachyhlroceras in the Cravenoceratidae, but without regarding subfamilies. Others (GONIAT) include Pachylyroceras in the Gravenoceratid subfamily

Cravenoceratinae Cravenoceratinae is one of two subfamilies of the family Cravenoceratidae. They are an extinct group of ammonoid, which are shelled cephalopods related to squids, belemnites, octopuses, and cuttlefish, and more distantly to the nautiloid Nauti ...

instead. The Treatise (Miller, Furnish, and Schindewolf 1957) includes ''Lyrogoniatites'', from which ''Pachylroceras'' is probably derived, in the subfamily Neoglyphioceratinae along with '' Neoglyphioceras'', but in the superfamily

Goniatitaceae Goniatitoidea, formerly Goniatitaceae in older publications, is a superfamily of late Paleozoic ammonoid cephalopods included in the Goniatitida Goniatids, informally goniatites, are Ammonoidea, ammonoid cephalopods that form the order Goniati ...

. The might suggest where ''Pachylyroceras'' might have been put, if it had been named and described at that time.

References

GONIAT online
* W. M. Furnish et al. 2009 Revised

Treatise A treatise is a formal and systematic written discourse on some subject, generally longer and treating it in greater depth than an essay, and more concerned with investigating or exposing the principles of the subject and its conclusions."Treat ...

Part L Vol

*D. Korn, 2006. Paleozoic ammonoid classification

*Saunders et al. 1999. Evolution of Complexity in Paleozoic Ammonoid Sutures, Supplementary Material

Carboniferous ammonites of North America Goniatitida genera Ammonites of North America Mississippian life Cravenoceratidae {{Goniatitida-stub