''Hildoceras'' is a genus of

ammonite Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

from the

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 ...

period in the family

Hildoceratidae Hildoceratidae is a family of ammonoid cephalopods from the Lower Jurassic, lower Pliensbachian (''Jamesoni'' zone) to lower Bajocian (maybe even upper Bajocian) substages, generally with strongly ribbed, involute shells. They are combined with ...

. The shells are characterized by a narrow discoidal evolute shape, keeled venter, concave ribs along the outer flanks, and a shallow spiral groove running along smooth inner flanks. Whorls slightly overlap, cross sections are compressed. The ventral keel is bordered on either side by a shallow groove. The genus was named by

Alpheus Hyatt Alpheus Hyatt (April 5, 1838 – January 15, 1902) was an American zoologist and palaeontologist. Biography Alpheus Hyatt II was born in Washington, D.C. to Alpheus Hyatt and Harriet Randolph (King) Hyatt. He briefly attended the Maryla ...

after

Saint Hilda Hilda (or Hild) of Whitby (c. 614 – 680) was a Christian saint and the founding abbess of the monastery at Whitby, which was chosen as the venue for the Synod of Whitby in 664. An important figure in the Christianisation of Anglo-Saxon Engla ...

in 1876.

Distribution

Jurassic of Bulgaria, France, Germany, Hungary, Italy, Japan, Luxembourg, Serbia and Montenegro, Spain, the United Kingdom and Iran.Seyed-Emami, Kazem, et al. "Toarcian and Aalenian (Jurassic) ammonites from the Shemshak Formation of the Jajarm area (eastern Alborz, Iran)." Paläontologische Zeitschrift 79.3 (2005): 349-369.

Species

* ''Hildoceras ameuri'' * ''Hildoceras apertum'' * ''Hildoceras bifrons'' * ''Hildoceras caterinii'' * ''Hildoceras crassum'' * ''Hildoceras lusitanicum'' * ''Hildoceras semipolitum'' * ''Hildoceras snoussi'' * ''Hildoceras sublevisoni'' * ''Hildoceras tethysi''

References

;Notes ;Bibliography * Ammonitida genera Hildoceratidae Jurassic ammonites Extinct animals of Europe Toarcian first appearances Middle Jurassic extinctions {{ammonitina-stub Toarcian life Jurassic ammonites of Europe Fossils of Serbia Fossils of Great Britain Fossils of France Fossils of Spain Fossils of Iran Fossils of Japan Fossils of Italy Fossils of Germany Fossils of Hungary