Clarkoceras
| Clarkoceras Temporal range:  | |
|---|---|
| Scientific classification | |
| Domain: | Eukaryota | 
| Kingdom: | Animalia | 
| Phylum: | Mollusca | 
| Class: | Cephalopoda | 
| Subclass: | Nautiloidea | 
| Order: | †Ellesmerocerida | 
| Family: | †Ellesmeroceratidae | 
| Genus: | †Clarkoceras Ruedemann, 1905 | 
Clarkoceras is a genus of breviconic ellesmerocerid cephalopods, one of only two genera known to have crossed from the Late Cambrian, Trempealeauan, into the Early Ordovician, Gasconadian. (Flower 1964, Teichert 1988); the other being Ectenolites.