Heptranchias howelli, the sevengill shark, is a nektonic carnivore in the genus Heptranchias. It is an extinct species that ranged from 37.2 to 20.43 Ma.
Fossil record
Teeth from Heptranchias howelli have been found in Europe. An antero-lateral tooth and an upper lateral tooth were found in Faxe, Denmark in 2014 . In addition, two incomplete antero-lateral teeth and an upper anterior tooth are kept in a private collection. A 2015 study in yielded a complete lower tooth, 17 incomplete lower teeth, and an unidentified broken tooth.
Description
Teeth
The upper lateral teeth of the species have a long, acute, strongly sigmoid main cusp. This cusp is serrated and has a dispal cusplet. The main cusp of the antero-lateral teeth is triangular and carries eight mesial cusplets that increase in size along the lower mesial face. The antero-lateral teeth have six main cusplets, the sixth of which is very small. The first cusplet is slightly lower than the others. The cusps are inclined at about a 45 degree angle distally.
The largest tooth found in Trelde Naes was mesio-distally, apico-basally and labio-langually. The root height ranged from .
Distribution
Fossils of Heptranchias howelli have been found in:
Eocene
La Meseta Formation, Seymour Island, Antarctica
Canada (British Columbia) United States (New Jersey, Oregon, Washington)