| Spyroceras Temporal range: Devonian |
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|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | Nautiloidea |
| Order: | Pseudorthocerida |
| Family: | Spyroceratidae |
| Genus: | Spyroceras Hyatt, 1884 |
Spyroceras is pseudorthocerid genus from the Devonian of North America and Europe, defined by Hyatt in 1884. Pseudorthocerids are a kind of orthocertaoid, a taxonomic group within the Nautiloidea. Specifically Spyroceras belongs to the pseudorthocerid family, Spyroceratidae.
Spyroceras was named for annulated orthocones with straight transverse sutures, transverse or slightly oblique surface annulations, and faintly cyrtoconic apeces. Surface ornamentation varies but longitudinal lirae are conspicuous from earliest stage. Siphuncle central or slightly offset ventrally, composed of expanded segments typical of the Pseudorthocerida. Cameral and siphonal deposits develop later than in most pseudorthocerids and are thus confined to the apical portion of the phragmocone.