Grammoceras

Grammoceras; Temporal range: Toarcian PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	Ammonoidea
Order:	Ammonitida
Superfamily:	Hildocerataceae
Family:	Hildoceratidae
Subfamily:	Grammoceratinae
Genus:	Grammoceras; Hyatt, 1867
Species
	Grammoceras striatulum (Sowerby, 1825); Grammoceras chateleti (De Brun, 1929); Grammoceras thouarsense (D’Orbigny, 1843); Grammoceras penestriatulum (Buckman, 1902); Grammoceras arenaceum (m) (Buckman, 1904); Grammoceras glabrum (m) (Monestier, 1921);

Grammoceras is an extinct genus of ammonite found in Yorks Ravenscar, England, from Jurassic period sediments. Its overall distribution is fairly worldwide.

Grammoceras has a thin, discoidally evolute shell with simple, gently sigmoid ribbing and a low ventral keel. and from the same age are similar except that Dumortiera has a more rounded venter and Catulloceras has a subquadrate whorl section. Asthenoceras from the slightly younger lower Bajocian may be a subgenus.

References[]

^ Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (Cephalopoda entry)". Bulletins of American Paleontology. 363: 1–560. Archived from the original on 2008-05-07. Retrieved 2017-10-18.

Arkell, W.J.; Kummel, B.; Wright, C.W. (1957). Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology, Part L, Mollusca 4. Lawrence, Kansas: Geological Society of America and University of Kansas Press.

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[Sepkoski_Ceph-1] Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (Cephalopoda entry)". Bulletins of American Paleontology. 363: 1–560. Archived from the original on 2008-05-07. Retrieved 2017-10-18.

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