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.
| Polyelasmoceratidae | |
|---|---|
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | Nautiloidea |
| Order: | †Oncocerida |
| Family: | †Polyelasmoceratidae Shimanskiy, 1956 |
| Genera | |
The Middle Silurian Danaoceras is probably the ancestral genus, which give rise to the contemporary Codoceras and ultimately the subsequent Devonian genera.
References
editThis article includes a list of references, related reading, or external links, but its sources remain unclear because it lacks inline citations. (March 2015) |
- Walter C. Sweet, 1964. Nautiloidea - Oncocerida; Treatise on Invertebrate Paleontology, Part K. Geological Society of America and University of Kansas Press.