Phricodoceratidae is a family in the Eoderoceratoidea, aberrant ammonites from the Lower Jurassic 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, (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