''Alaoceras'' is an

ammonoid 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 cuttlefish) ...

cephalopod from the upper

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

included in the goniatitid 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 ...

, named by Ruzhentsev & Bogoslovskaya in 1971. ''Alaoceras'' is characterized by its generally subdiscoidal shell with moderately involute whorls and a wide or moderately wide umbilicus, ornamented with sharply defined lamellae, very weak and sometimes disappearing lirae, and elongated protuberances on the umbilical wall. Normally there are one or two constrictions per revolution. The suture is goniatitic with a widely diverging bifurcated ventral lobe in which the height of the median saddle is less than half of the whole lobe. ''Alaoceras'' is probably derived from ''

Pachylyroceras ''Pachylyroceras'' is a large, generally subglobular, Upper Mississippian gonitite and included in the cephalopod subclass Ammonoidea. Recognition ''Pachylyroceras'' produced a large shell that is moderately evolute to moderately involute and ...

'', which it resembles overall.

References

External links

GONIAT online

Paleobiology-Alaoceras
* Saunders, Work, and Nikolaeva, 1999. Evolution of Complexity in Paleozoic Ammonoid Sutures, Supplementary Material

Cravenoceratidae Goniatitida genera {{Goniatitida-stub