User:Wiki.Ichthys/Diademodus

Diademodus is an extinct genus of phoebodontiform elasmobranch with fossils from the late Devonian of Ohio, Utah, Nevada, and Western Australia. The genus is known mostly from fossilized teeth along with one well-preserved body impression.

Diademodus was a relatively small shark with a long, slender body estimated to have reached 40 centimeters (1.3 feet) in length. It had notably reduced pectoral fins, a single anteriorly placed dorsal fin, and features indicative of a heterocercal caudal fin. The teeth of Diademodus were approximately 1 millimeter wide and had three to four main cusps. Additionally, it possessed at least three intermediate cusplets between each cusp, a trait that is uncommon in other phoebodontiformes. It is theorized to have been a relatively poor swimmer and may have lived near the sea floor.

Diademodus hydei
The type species. It is based on a body impression from the Cleveland Shale of Ohio. The specific epithet is in honor of Dr. Hyde, a professor of geology at Case Western Reserve University. The teeth of D. hydei were initially described as having ten cusps in total, with the two middlemost and outermost cusps being the largest. However, the middlemost cusps were reinterpreted as a single large cusp in 2008. The fossil contains fish scales in the gut area, suggesting that the animal was carnivorous.

Diademodus utahensis
The second species described, known from the Pilot Shale of Utah and Nevada. This species only possessed one middlemost cusp as opposed to D. hydei’s initially proposed two. One recovered tooth has an additional, asymmetrical cusplet, making it the first species of Diademodus to exhibit heterodonty. It has been suggested that the teeth of D. utahensis were too delicate to grasp prey and were instead used in filter feeding.

Diademodus dominicus
The third species described and the first species discovered outside of Laurussia, from the Virgin Hills Formation of Western Australia. The specific epithet is in honor of Mr. Dominicus 'Tim' Mueller, M.Sc. This species' teeth are characterized by three large cusps like that of D. utahensis, but with overall tooth anatomy that more closely resembles D. hydei.