Agassizodus

Agassizodus
Temporal range: Pennsylvanian
Fossil tooth whorl
Scientific classification Edit this classification
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

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 in the upper right, Romerodus, and the center, and Listracanthus behind

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]

  1. ^ 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.
  2. ^ a b Eaton, Theodore H. (1 October 1962). "Teeth of Edestid Sharks". University of Kansas Publications, Museum of Natural History. 12 (8): 347–362.
  3. ^ Zangerl, R. (1981). Chondrichthyes I – Paleozoic Elasmobranchii. Handbook of Paleoichthyology. Stuttgart: Gustav Fischer Verlag. pp. i–iii, 1–115.
  4. ^ 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.