| Spyroceratidae | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Order: | † Pseudorthocerida |
| Family: | † Spyroceratidae Shimazu & Obata 1935 |
Spyroceratidae are defined [1] as Pseudorthocerida with uniformly slender siphuncle segments, longer than wide, that contract sharply near either end, in which endosiphuncular deposits first form a compete annulus before fusing ventrally.
