''Alaoceras'' is an

ammonoid Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...

cephalopod from the upper

Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...

included in the goniatitid family Cravenoceratidae, 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'', 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