Agassizodus is an extinct genus of eugeneodont holocephalian from the Carboniferous. It belongs to the family Helicoprionidae, which is sometimes called Agassizodontidae. Like other members of its family, it possessed a symphyseal tooth whorl, which was likely present at the tip of the lower jaw and associated with lateral crushing toothplates.[1] The type species, A. variabilis, was originally named Lophodus variabilis until the name "Lophodus" was determined to be preoccupied.[2]
| Agassizodus Temporal range:
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|---|---|
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| Fossil tooth whorl | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Holocephali |
| Order: | †Eugeneodontida |
| Family: | †Helicoprionidae |
| Genus: | †Agassizodus St. John and Worthen 1875 |
| Type species | |
| †Agassizodus variabilis Newberry and Worthen, 1870
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A. variabilis was originally based on tooth fragments from the Pennsylvanian of Illinois, but the authors who named the genus (St. John and Worthen, 1875) also referred a massive jaw from Osage County, Kansas. The Osage jaw shared some similarities to tooth-whorls from the area, which were later described by Eastman (1902). Eastman concluded that the tooth whorls and jaw belonged to Campodus, so he renamed Agassizodus variabilis to Campodus variabilis.[2] Other authors disagree, arguing that the Eastman specimens and the Osage jaw represent neither Agassizodus or Campodus, but rather an entirely new genus.[3][4]
References
edit- ^ Tapanila, Leif; Pruitt, Jesse; Wilga, Cheryl D.; Pradel, Alan (2020). "Saws, Scissors, and Sharks: Late Paleozoic Experimentation with Symphyseal Dentition". The Anatomical Record. 303 (2): 363–376. doi:10.1002/ar.24046. ISSN 1932-8494. PMID 30536888.
- ^ a b Eaton, Theodore H. (1 October 1962). "Teeth of Edestid Sharks". University of Kansas Publications, Museum of Natural History. 12 (8): 347–362.
- ^ Zangerl, R. (1981). Chondrichthyes I – Paleozoic Elasmobranchii. Handbook of Paleoichthyology. Stuttgart: Gustav Fischer Verlag. pp. i–iii, 1–115.
- ^ Ginter, Michał (2018). "The dentition of a eugeneodontiform shark from the Lower Pennsylvanian of Derbyshire, UK" (PDF). Acta Palaeontologica Polonica. 63 (4): 725–735. doi:10.4202/app.00533.2018.
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