Endocerida

Endocerida Temporal range: Floian–Hirnantian[1][2] PreꞒ Ꞓ O S D C P T J K Pg N
The massive endocerid Cameroceras (middle) alongside other nautiloids
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	Nautiloidea
Superorder:	†Endoceratoidea
Order:	†Endocerida Teichert, 1933
Families
† Cyrtendoceratidae † Endoceratidae † Proterocameroceratidae † Yorkoceratidae

Endocerida is an extinct nautiloid order, a group of cephalopods from the Lower Paleozoic with cone-like deposits in their siphuncle. Endocerida was a diverse group of cephalopods that lived from the Early Ordovician possibly to the Late Silurian. Their shells were variable in form. Some were straight (orthoconic), others curved (cyrtoconic); some were long (longiconic), others short (breviconic). Some long-shelled forms like Endoceras attained shell lengths close to 6 metres (20 ft). The related Cameroceras is anecdotally reported to have reached lengths approaching 9 metres (30 ft), but these claims are problematic. The overwhelming majority of endocerids and nautiloids in general are much smaller, usually less than a meter long when fully grown.