Jolietoceras is a compressed, annulate, lituiconic nautiloid included in the derived Tarphycerid family, Uranoceratidae. The shell is gyroconic in the early stage, becoming straight and more rapidly expanded in the later. sutures are straight and transverse. Surface annuli slope strongly to the rear, dorso-ventrally, in the early gyroconic stage but a lacking in the later straight segment.
| Jolietoceras Temporal range: Middle Silurian
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | Nautiloidea |
| Order: | †Tarphycerida |
| Family: | †Uranoceratidae |
| Genus: | †Jolietoceras Foerste, 1925 |
Jolietoceras comes from the Middle Silurian of the United States (Illinois, Wisconsin).
The Uranoceratidae, including Jolietoceras, were one included in the Barrandeocerida (Sweet, 1964), which has since been incorporated into the Tarphycerida.
References edit
- Sweet, W. C. 1964 Nautiloidea- Barrandeocerida. Treatise on Invertebrate Paleontology, Part K. Geol Soc of America and Univ of Kansas Press. Teichert & Moore, (eds)