Eoderocerataceae is a superfamily of true ammonites (suborder Ammonitina

Ammonitina

The Ammonitina comprises a diverse suborder of ammonoid cephalopods that lived during the Jurassic and Cretaceous periods of the Mesozoic Era. They are excellent index fossils, and it is often possible to link the rock layer in which they are found to specific geological time periods.The shells of...

) from the Lower Jurassic

Jurassic

The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

, 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

Apoderoceras

Apoderoceras is an extinct genus of cephalopod belonging to the Ammonite subclass....

, Epideroceras, and Liparoceras.
The earliest known eodoceroceratacean is the eoderoceratid genus Microderoceras

Microderoceras

Microderoceras is a flat sided, evolute, radially ribbed Lower Jurassic ammonite belonging to the ammonitid family Eoderoceratidae and superfamily Eoderocerataceae...

. Although its origin is uncertain, it is likely that it is derived from the Psilocerataceae

Psilocerataceae

The Psilocerataceae is a superfamily of Early Jurassic ammonoid cephalopods proposed by Alpheus Hyatt in 1867, assigned to the order Ammonitida....

. It has also been proposed, with some imagination, that Microderoceas has its origin some earlier Jurassic lytoceratid

Lytoceratina

Lytoceratina is a suborder of Jurassic and Cretaceous ammonites that produced loosely coiled, evolute and gyroconic shells in which the sutural element are said to have complex moss-like endings.-Morphologic characteristics:...

 such as Analytoceras

Analytoceras

Analytoceras is an extinct genus of cephalopod belonging to the Ammonite subclass....

.

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

Hildocerataceae

Hildocerataceae 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....

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 Eoceroceratidae but the Dactylioceratidae were derived separately (1957) from the Lytoceratidae - a source since then largely rejected.