Eoderoceratoidea is a superfamily of true ammonites (suborder Ammonitina) from the Lower Jurassic, comprising seven phylogenetically related families, characterized in general by having ribbed evolute shells that commonly bear spines or tubercles. Adult shell size ranges from 2 or 3 cm to giants reaching 50 cm in such genera as '' Apoderoceras'', '' Epideroceras'', and ''

Liparoceras Liparoceras is an extinct fossil ammonite species from the Early Jurassic period of England, and is found in lower Lias deposits. Its name means 'fat head' and this is due to its broad shell. The venter is wide and finely ribbed with no keel and ...

''.Donovan,D.T., Callomon and Howarth 1981. Classification of the Jurassic Ammonitina; Systematics Association. Arkell ''et al.'', 1957. Mesozoic Ammonoidea, in Treatise on Invertebrate Paleontology, (Part L); Geological Soc. of America and University of Kansas press The earliest known eodoceroceratoidean is the eoderoceratid genus ''

Microderoceras ''Microderoceras'' is a flat sided, evolute, radially ribbed Lower Jurassic ammonite belonging to the ammonitid family Eoderoceratidae and superfamily Eoderoceratoidea. Its whorls are subquadrangular in section; venter on the outer rim, rounde ...

''. Although its origin is uncertain, it is likely that it is derived from the Psiloceratoidea. It has also been proposed, with some imagination, that ''Microderoceas'' has its origin some earlier Jurassic

lytoceratid Lytoceratidae is a taxonomic family of ammonoid cephalopods belonging to the suborder Lytoceratina, characterized by very evolute shells that generally enlarge rapidly, having whorls in contact but mostly overlapping very sightly, or not at all. ...

such as ''

Analytoceras ''Analytoceras'' is an extinct genus of cephalopod belonging to the Ammonite subclass that lived during the early Jurassic. ''Analytoceras'', named by Alpheus Hyatt in 1900, is a Lytoceratida, lytoceratid and only member of the Pleuroacanthitidae, ...

''. Seven families are included, beginning with the Eoceroceratidae, which gave rise at about the same time to the Phricodoceratidae, Coeloceratidae, Liparoceratidae, and Polyhmorphitidae. The Phricodoceratidae left no descendants but the Coeloceratidae later gave rise to the Dactylioceratidae and the Liparoceratidae to the Amaltheidae. The Polymorphitidae became the source for the superfamilies

Hildocerataceae Hildoceratoidea, formerly Hildoceratacaea, is a superfamily of compressed or planulate ammonites, some tending to develop acute outer rims; generally with arcuate or sigmoidal ribs. Aptichus were found in place are double-valved.Arkell ''et al.' ...

beginning with the Hildoceratidae. The more recent taxonomy of Donovan et al. (1981) with seven families, differs from that of Arkell, et al. in the Treatise (1957) which included just five families. The phricodoceratids and coeoloceratids were then considered as subfamilies (Phricodoceratinae and Coeloceratinae, respectively) of the Eoderoceratidae. As later (1981) the Liparoceratidae and Polyhmorphitidae were derived from the Eoderoceratidae but the Dactylioceratidae were derived separately (1957) from the Lytoceratidae - a source since then largely rejected.

References

Ammonitida superfamilies Jurassic ammonites Early Jurassic first appearances Early Jurassic extinctions {{Ammonitina-stub