''Barroisiceras'' is an acanthoceratacean

ammonite 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) ...

from the

Upper Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

Coniacian The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by t ...

, included in the family

Collignoniceratidae Collignoniceratidae is a family of Upper Cretaceous ammonites characterized by typically more or less evolute shells with compressed, oval, or square whorl sections; serrate or entire keels; and dense ribs with one to 5 tubercles. Taxonomy This ...

Diagnosis

The shell of ''Barroisiceras'' is rather involute, coiled such that the outer whorl embraces much of the previous, and is generally compressed. Whorls are high with a strong crenulate keel and sparse umbilical tubercles that develop into pairs of commonly flat ribs.

Taxonomy

''Barroisiceras'' is divided two subgenera, ''Barroisiceras (Barroisiceras)'' and ''Barroisiceras (Texasia)'',with '' Alstadenites'' sometimes added as a third, ''Barroisiceras (Alstadenites)''. ''B. (Barroiciceras)'' is moderately involute and the suture is rather simple. ''B. (Texasia)'' is more evolute and has a distinctly eccentric umbilicus and more complex suture.

Distribution

Cretaceous of Austria, Czechoslovakia, France, Hungary, Italy, Japan, Morocco, Slovakia, Spain, Trinidad and Tobago and USSR

References

;Notes ;Bibliography * Arkell ''et al.'', 1957. Mesozoic Ammonoidea

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and co ...

part L, Ammonoidea. Ammonitida genera Collignoniceratidae Cretaceous ammonites Ammonites of Europe Coniacian life {{Ammonitina-stub