Phricodoceratidae is a family in the

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 ...

, aberrant ammonites 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 ...

characterized by a large adult size and a marked change of shell form and ornament with growth. Shells are stoutly ribbed, early growth stage is round-whorled with spines, followed by a high-whorled late growth stage with smooth, modified ribbing. Three genera are currently placed in the Phricodoceratidae: '' Phricodoceras'', '' Epideroceras'', and '' Pseuduptonia''.

References

*Arkell ''et al.'', 1957. Mesozoic Ammonoidea, in

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); Geological Soc. of America and University of Kansas press. *Donovan, Callomon, and Howarth 1981 Classification of the Jurassic Ammonitina; Systematics Association

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