Polyelasmoceratidae is a family of
oncocerid nautiloids characterized by rapidly expanding endogastrically curved shells, curved such that the ventral side is longitudinally concave. In cross section shells are typically tear-drop in shape to subtriangular. The siphuncle is typically nummuloidal, like a string of beads, with outwardly flared septal necks, and located between the center and the venter. Most contain radially lamellar actinosiphonate deposits.
The Middle Silurian ''
Danaoceras
''Danaoceras'' is a nautiloid cephalopod from the middle Silurian of central Europe included in the oncoceroid family Polyelasmoceratidae. Similar specimens from the middle Devonian of North America may belong.
''Danaoceras'' has a laterally co ...
'' is probably the ancestral genus, which give rise to the contemporary ''
Codoceras'' and ultimately the subsequent Devonian genera.
References
* Walter C. Sweet, 1964. Nautiloidea - Oncocerida; Treatise on Invertebrate Paleontology, Part K. Geological Society of America and University of Kansas Press.
{{Taxonbar, from=Q19760186
Oncocerida
Silurian first appearances
Middle Devonian extinctions
Nautiloid families