''Crucilobiceras'' 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 genus from the

Lower Jurassic The Early Jurassic Epoch (in chronostratigraphy corresponding to the Lower Jurassic Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-Jurassic extinction event, 201.3 Ma ...

belonging to the eoderoceratoidean family

Eoderoceratidae Eoderoceratidae is the ancestral and most primitive family of the Eoderoceratoidea; lower Jurassic ammonite cephalopods, characterized by evolute, commonly serpenticonic, shells that had long body chambers and would have had no stable floating ...

. ''Cruciliboceras'' has an evolute shell, such that all whorls are well exposed, with persistent radial ribbing and with spines or tubercles on the outer, ventral, rim, and in some, tubercles in the inner, umbilical, rim. The genus ''Crucilobiceras'' is commonly found along the Jurassic Coast of England. ''Metaderoceras'', named by Leonard Spath in 1925, is a jr. synonym for ''Crucilobiceras'' named by S.S. Buckman in 1920 according to Arkell ''et al.'', in the

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 ...

(1957).

References

;Notes ;Bibliography *Arkell ''et al.'', 1957. Mesozoic Ammonoidea, in Treatise on Invertebrate Paleontology, (Part L); Geological Soc. of America and University of Kansas press *Donovan, Callomon and Howarth 1981 Classification of the Jurassic Ammonitina; Systematics Association

Early Jurassic ammonites of Europe Ammonites of Europe Fossil taxa described in 1920 Ammonitida genera Eoderoceratoidea {{Ammonite-stub