''Amaltheus'' is an oxyconic ammonite with a fairly open umbilicus, serrated keel, and slightly sigmoidal ribs from the Lower

Jurassic The Jurassic ( ) is a geologic period and 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 Jurassic constitutes the middle period of ...

, many of which are strigate. ''Amaltheus'', named by de Montfort, 1808, is indicative of the upper

Pliensbachian The Pliensbachian is an age (geology), age of the geologic timescale and stage (stratigraphy), stage in the stratigraphic column. It is part of the Early Jurassic, Early or Lower Jurassic epoch (geology), Epoch or series (stratigraphy), Series an ...

stage in Europe, north Africa, Caucasus, Siberia, N. Alaska, Canada, Oregon, and possibly Honduras; and is the type for the Amaltheidae and a member of the Eoderoceratoidea. Two subgenera are recognized. One, ''A.(Amaltheus)'' is already described. The other ''A. (Pseudoamaltheus)'', sometimes expressed as genus, is a late derivative of (''Amaltheus'') with an early loss of keel and ribbing and an extreme development of strigation.

References

;Notes ;Bibliography * Arkell ''et al.'', 1957. Mesozoic Ammonoidea. Treatise in Invertebrate Paleontology, Part L; Geological Society of America and University Kansas press. * Donovan, Collomon,& Howarth. Classification of the Jurassic Ammonitina, in The Ammonoidea, M.R. House and J.R. Senior (eds) Academic Press 1981. Systematics Association Special Volume. 18

Ammonitida genera Eoderoceratoidea Jurassic ammonites Early Jurassic ammonites of Europe Fossil taxa described in 1808 {{Ammonitina-stub