Liparoceratidae is a family of

eoderoceratoidea 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 tubercle ...

n ammonites from the Lower

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

that combines genera with a variety of forms including dimorphs that change from one form to another during

ontogeny Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the stu ...

. Three genera and six subgenera are included in the Liparoceridae according to D.T. Donovan in Donovan ''et al.'' 1981; '' Liparoceras'' including ''L''. (''Liparoceras''), ''L''. (''Becheiceras''), and ''L''. (''Vicininodiceras''); '' Aegoceras'' including ''A''. (''Aegoceras''), ''A''. (''Beaniceras''), and ''A''. (''Oistoceras''); and '' Androgynoceras''. Arkell, ''et al.'' (1957) in the Treatise on Invertebrate Paleontology, Part L list ''Liparoceras'' with ''Becheiceras'' and ''Vincininodiceras'' along with '' Parinodiceras'' separately as subgenera; ''Beaniceras'', '' Metacymbites'', ''Oistoceras'', and '' Platynoticeras'' but leave out ''Aegoceras''. ''Parinodiceras'' and its equivalent, '' Platynoticeras'' are removed (Donovan 1981) to the

Polymorphitidae Polymorphitidae is a family of Early Jurassic ammonoid cephalopods that contribute to the Eoderoceratoidea. Two subfamilies, the Polymorphtinae and Tropidoceratinae, are included. Polymorphitid ammonites produced typically evolute shells, whi ...

. ''Metacymbites'' is a smooth dwarf and may form a dimorphic pair with ''Liparoceras''. The Liparoceratidae are thought to have evolved from the

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 ...

along with the Coeloceratidae and

Polymorphidae The thorny-headed worm family Polymorphidae contains endoparasites which as adults feed mainly in fish and aquatic birds. When this taxon was erected by Meyer in 1931, a subfamily Polymorphinae was established in it. As the Polymorphidae as ...

close to the same time during the

Sinemurian In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic Epoch or Series. It spans the time between 199.3 ± 2 Ma and 190.8 ± 1.5 Ma (million years ago). The Sinemurian is preceded by the Hettangian and is ...

stage of the Early Jurassic, and in the following

Pliensbachian The Pliensbachian is an age of the geologic timescale and stage in the stratigraphic column. It is part of the Early or Lower Jurassic Epoch or Series and spans the time between 190.8 ± 1.5 Ma and 182.7 ± 1.5 Ma (million years ago). The Plien ...

gave rise to the

Amaltheidae Amaltheidae is a family of eoderoceratoidean ammonitids from the Lower Jurassic consisting of genera characterised by stigated discoidal oxycones—narrow involute shells with narrowly rounded to angular venters that bear a series of grooves, or ...

References

*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

Liparoceratidae, Ammonitida families Eoderoceratoidea Pliensbachian first appearances Early Jurassic extinctions {{Ammonitina-stub