The Late Cretaceous Chimaeroid Fish, Ischyodus bifurcatus Case (Chondrichthyes: Holocephali), from California, USA, and Its Paleobiogeographical Significance

Evan D. Johnson-Ransom, Evgeny V. Popov, Thomas A. Deméré, Kenshu Shimada

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A nearly complete right mandibular tooth plate of Ischyodus bifurcatus Case (Holocephali: Chimaeroidei) is reported from the Point Loma Formation (upper Campanian) of the Upper Cretaceous Rosario Group in southern California, USA. The individual is estimated to have measured nearly 1 m in total body length. Remains of I. bifurcatus have been reported from marine rocks deposited in epicontinental seas and continental shelf paleoenvironments of temperate latitudes in the Northern Hemisphere. Previous records of the species consist of specimens from Santonian to Maastrichtian strata of the US (Delaware, New Jersey, North Carolina, Georgia, Alabama, Arkansas, Montana, and Wyoming), Sweden, and European Russia. The tooth plate described herein is the first verifiable record of I. bifurcatus from California, and, more significantly, represents the only known definite Mesozoic record of Ischyodus from the entire North Pacific region.

Original languageEnglish
Pages (from-to)364-372
Number of pages9
JournalPaleontological Research
Issue number4
Publication statusPublished - 1 Oct 2018
Externally publishedYes



  • chimaeroid fish
  • Ischyodus
  • Late Cretaceous
  • North Pacific
  • tooth plate

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