Eugeneodontida

The Eugeneodontida is an extinct and poorly known order of cartilaginous fishes. They possessed a unique "tooth-whorl" on the symphysis of the lower jaw and pectoral fins supported by long radials. The palatoquadrate was either fused to the skull or reduced. Now determined to be within the Holocephali, their closest living relatives are ratfish.[3] The meaning of the name Eugeneodont correlates to "true origin teeth", and comes from the Greek eu (good/true), geneos (race, kind, origin), and odon (tooth). The Eugeneodontida disappeared in the Early Triassic.[4]

Eugeneodontida
Temporal range: 407.7–247.2 Ma Late Devonian to Olenekian[1]
Helicoprion bessonovi
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Superorder: †Paraselachimorpha
Order: †Eugeneodontida
Zangerl, 1981
Subdivisions

see text

Synonyms
  • Eugeneodontiformes[2]

Members of the Eugeneodontida are further classified into different families, the most well-preserved members that have been discovered are commonly placed within the families Helicoprionidae ("spiral saws"), and Edestidae ("those which devour"), the former containing the genera Helicoprion, Sarcoprion, and Parahelicoprion, and the latter containing the genera Edestus, Lestrodus, and Metaxyacanthus. All eugeneodonts are thought to have been obligate carnivores, with each genus having specialized feeding behaviors, territory ranges, and specific prey.

Taxonomy

References
  1. Mutter, Raoul J., and Andrew G. Neuman. "New eugeneodontid sharks from the Lower Triassic Sulphur Mountain Formation of Western Canada." Geological Society, London, Special Publications 295.1 (2008): 9-41.
  2. The Paleobiology Database - Eugeneodontiformes
  3. Tapanila L.; Pruitt J.; Pradel A.; Wilga C.; Ramsay J.; Schlader R.; Didier D. (2013). "Jaws for a spiral-tooth whorl: CT images reveal novel adaptation and phylogeny in fossil Helicoprion". Biology Letters. 9 (2): 20130057. doi:10.1098/rsbl.2013.0057. PMC 3639784. PMID 23445952.
  4. Scheyer, Torsten M.; Romano, Carlo; Jenks, Jim; Bucher, Hugo (19 March 2014). "Early Triassic Marine Biotic Recovery: The Predators' Perspective". PLOS ONE. 9 (3): e88987. Bibcode:2014PLoSO...988987S. doi:10.1371/journal.pone.0088987. PMC 3960099. PMID 24647136.


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