| Romerodus | |
|---|---|
| |
| Skeletal reconstruction of R. orodontus, with well described material in white and preserved but poorly defined material in gray. The body outline as shown represents the extent of phosphatized skin. | |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Holocephali |
| Order: | †Eugeneodontida |
| Family: | †Caseodontidae |
| Genus: | †Romerodus Zangerl, 1981 |
| Type species | |
| Romerodus orodontus Zangerl, 1981
| |
Romerodus (meaning "Alfred Romer's tooth") is an extinct genus of cartilaginous fish in the family Caseodontidae. While it and the rest of its family were historically considered elasmobranchs related to sharks and rays, they are now regarded as holocephalans, a diverse subclass which is today only represented by chimaeras. Romerodus is known from the Carboniferous and possibly Permian periods of North America, and the only named species, R. orodontus, was discovered in organic shale deposits in the U.S. state of Nebraska. It is one of few members of its order, the Eugeneodontida, that is known from multiple complete, well preserved body fossils, and is thus an important taxon for understanding the anatomy and ecology of less well preserved eugeneodonts such as Helicoprion. Unlike its larger relatives, the largest known Romerodus were approximately 50 cm (20 in) in total length.
The body of R. orodontus was similar to that of other caseodontids. It possessed a slender, streamlined profile, a strongly keeled crescent-shaped caudal fin, and proportionally very small dorsal and pectoral fins. Unlike modern sharks and rays, there is no indication Romerodus possessed pelvic fins or claspers. Its teeth were smoother and less ornamented than those of other caseodonts, and were positioned in tightly-packed rows. It inhabited deep-water marine environments, and shows adaptations associated with life as a pelagic carnivore.