Aulacocerida
Aulacocerida | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Mollusca |
Class: | Cephalopoda |
Superorder: | †Belemnoidea |
Order: | †Aulacocerida Stolley 1919 |
Aulacocerida is an order of primitive coleoid cephalopods, possibly derived from michelinoceraitids (Orthocerida) early in the Devonian, which in turn gave rise to the Belemnites.
Aulococerids are characterized by a straight, slim, conical shell with a large living chamber, simple aperture. The protoconch (initial, embryonic chamber) is egg-shaped and separated from the phragmocone by a constriction. The siphuncle is narrow and ventral, constricted at the septa and expanded in the middle of the chamber; necks are retrochoantiic[.
Opinions vary as to whether aulococerids were endocochleate,
See also
- List of belemnites
References
- S2CID 201208912.
- Klaus Bandel, J. Reitner, and W. Sturmer, 1893. Coleoids from the Lower Devonian Black Slate (Hunstruck-Shiefer) of the Hunsruck (West Germany). N Jb Geol Paliont Abh 165(3) 397-414 Stuttgart, Apr 1983.
- Klaus Bandel, 1985. Composition and ontogeny of Dictyoconites (Aulacocerida, Cephalopoda). Palaont Z 59(3/4),223-244. Stuttgart, Dec 1985.