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| Wiki.Ichthys/Diademodus Temporal range: Late Devonian
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Clade: | †Phoebodontiformes |
| Genus: | †Diademodus Harris, 1951 |
| Type species | |
| †Diademodus hydei Harris, 1951
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| Species | |
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Diademodus is an extinct genus of phoebodontiform elasmobranch known from the late Devonian of Ohio, Utah, Nevada, and Western Australia. It 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 the Case Western Reserve University. Unlike other species of Diademodus, this species’ teeth were initially described as having ten cusps in total, with the two outermost and two middlemost being larger main cusps. However, Michał Ginter later reinterpreted the two middlemost cusps as one large cusp in 2008. 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 proposed two. It also the first species of Diademodus to exhibit heterodonty, as one of the recovered teeth possesses a single, asymmetrical cusplet. It is argued that the teeth of D. utahensis were too delicate to grasp prey and were instead used in filter feeding, with a function similar to that of a sieve to trap tiny organisms inside the mouth before swallowing.[2]
Diademodus dominicus edit
The third species described and the first species to be found outside of Laurussia. It is 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 main cusps like that of D. utahensis, but with overall tooth anatomy that more closely resembles D. hydei.[3]
References edit
- ^ 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.
- ^ a b c Ginter, Michał (2008). "Devonian filter-feeding sharks". Acta Geologica Polonica. 58 (2): 147–153.
- ^ 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). doi:10.1515/agp-2015-0003. ISSN 0001-5709.
External links edit