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Wiki.Ichthys/Diademodus
Temporal range: Late Devonian Frasnian–Famennian
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Clade: Phoebodontiformes
Genus: Diademodus
Harris, 1951
Type species
Diademodus hydei
Harris, 1951
Species
  • D. hydei (Harris, 1951)
  • D. utahensis (Ginter, 2008)
  • D. dominicus (Roelofs et al., 2015)

Diademodus is an extinct genus of phoebodontiform elasmobranch with fossils from the late Devonian of Ohio, Utah, Nevada, and Western Australia. The species is known mostly from fossilized teeth along with one well-preserved body impression.[1][2][3]

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 uncommon in other phoebodontiformes. It is believed to have been a relatively poor swimmer and may have lived near the sea floor.[1]

Species[edit]

Diademodus hydei[edit]

The type species. It is based on a well-preserved 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. This species’ teeth were initially described as having ten cusps in total, with the two outermost and two middlemost cusps being the largest. In 2008, the middlemost cusps were reinterpreted by Michał Ginter as a single large cusp. The fossil contains fish scales in the gut area, suggesting that the animal was carnivorous.[1][2]

Diademodus utahensis[edit]

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 of the recovered teeth has an additional, asymmetrical cusplet, making it the first species of Diademodus to exhibit heterodonty. It is suggested that the teeth of D. utahensis were too delicate to grasp prey and were instead used in filter feeding.[2]

Diademodus dominicus[edit]

The third species described and the first species to be found outside of Laurussia, with fossils described from the Virgin Hills Formation of Western Australia. The specific epithet is in honor of Mr. Dominicus ‘Tim’ Mueller, M.Sc. It had teeth with three large cusps like that of D. utahensis, but with overall tooth anatomy that more closely resembled D. hydei.[3]

References[edit]

  1. ^ a b c Harris, John E. (1951). "Diademodus hydei, a new fossil shark from the Cleveland Shale". Proceedings of the Zoological Society of London. 120 (4): 683–697. doi:10.1111/j.1096-3642.1951.tb00672.x. ISSN 0370-2774.
  2. ^ a b c Ginter, Michał (2008). "Devonian filter-feeding sharks". Acta Geologica Polonica. 58 (2): 147–153.
  3. ^ a b Trinajstic, Kate; Playton, Ted; Roelofs, Brett; Barham, Milo (2015). "Upper Devonian microvertebrates from the Canning Basin, Western Australia". Acta Geologica Polonica. 65 (1): 69–101. Bibcode:2015AcGeP..65...69R. doi:10.1515/agp-2015-0003. ISSN 0001-5709.

Category:Phoebodontiformes Category:Frasnian life Category:Famennian life Category:Late Devonian cartilaginous fish Category:Devonian cartilaginous fish of North America Category:Devonian cartilaginous fish of Australia Category:Fossil taxa described in 1951