Hiodon consteniorumgroup is extinct

Guo-Qing Li and Mark V. H. Wilson
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Containing group: Hiodon


Hiodon consteniorum is the only known fossil species of Hiodon. It was discovered in the Kishenehn Formation exposed along the Middle Fork of the Flathead River, northwestern Montana (Li and Wilson, 1994). The discovery of this fossil species of Hiodon extends the evolutionary history of this genus to the late Eocene.


Hiodon consteniorum differs from the two extant species in the following features:

  1. Mid-dorsal concavity on premaxillary bone deeper and narrower.
  2. Maxillary bone posteriorly more expanded and extending not beyond posterior 1/3 of the orbit.
  3. Basihyal tooth plate longer (more than 3/5 versus about 1/2 as long as the lower jaw in the two Recent species).
  4. Fewer vertebrae (52-53 versus 55-61 or 63 in extant species).
  5. Fewer anal pterygiophores (20 versus 27 - 36 in extant species) (see the Hiodon tergisus and Hiodon alosoides pages for more details).

This species is also distinguishable from the two extant species in the following ratios: standard length to body depth ratio about 3.3-3.6 (vs. 3.0-3.1 in Hiodon tergisus and 3.3-3.4 in Hiodon alosoides), predorsal length to preanal length ratio about 0.83-0.84 (vs. 0.92-0.93 in Hiodon tergisus and 1.06-1.11 in Hiodon alosoides), and anal-fin base length to dorsal-fin base length about 1.24-1.35 (vs. 2.02-2.04 in Hiodon tergisus and 2.74-3.12 in Hiodon alosoides) (see Li and Wilson 1994 for more detail).


Li G.-Q. and M. V. H. Wilson. 1994: An Eocene species of Hiodon from Montana, its phylogenetic relationships, and the evolution of the postcranial skeleton in the Hiodontidae (Teleostei). Journal of Vertebrate Paleontology, 14: 153-167.

Title Illustrations
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Scientific Name Hiodon consteniorum
Specimen Condition Fossil
Sex Male
Size standard length of 61mm
Type Holotype
Copyright © 1998 Guo-Qing Li and Mark V. H. Wilson
About This Page

Chinese Academy of Sciences, Beijing , China

University of Alberta, Edmonton, Alberta, Canada

Correspondence regarding this page should be directed to Guo-Qing Li at and Mark V. H. Wilson at

All Rights Reserved.

Citing this page:

Li, Guo-Qing and Mark V. H. Wilson. 1998. Hiodon consteniorum. Version 01 January 1998. in The Tree of Life Web Project,

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