''Bisatoceras'' is a late Paleozoic (Upper Mississippian - Upper Pennsylvanian)
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 ...
, a member of the goniatitid family
Bisatoceratidae.
''Bisatoceras'' was named by Miller and Owen in 1937 and has a subdiscoidal shell with a very narrow or closed umbilicus. Whorl height exceeds with at maturity, immature growth stages are globular. Growth lines are usually biconvex, forming ventral and lateral sinuses. Two or three lateral constrictions are formed on each whorl during early growth stages but constrictions are absent at full maturity. The ventral lobe of the suture is double pronged with the median saddle exceeding two thirds the height of the lobe itself.
''Pseudobisatoceras'', named by Maksimova, 1940, is like ''Bisatoceras'' but is distinct in having spiral ornamentation. Its temporal range coincides with the early part of that of ''Bisatoceras''.
Miller ''et al'' considered ''Pseudobisatoceras'' a synonym for ''Bisatoceras'' which was included in the family
Goniatitidae
Goniatitidae is one of three families included in the ammonoid cephalopod superfamily Goniatitoidea, known from the Lower Mississippian to the Upper Permian
The Permian ( ) is a geologic period and stratigraphic system which spans 47 millio ...
and subfamily Bisatoceratinae.
References
*''Bisatoceras'' and ''Pseudobisatoceras'' i
GONIAT Online6/14/12
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Goniatitida genera
Bisatoceratidae
Paleozoic life of Nunavut
{{Goniatitida-stub