Kingdom Animalia Class Chondrichthyes Superorder Selachimorpha | Phylum Chordata Subclass Elasmobranchii Order Hexanchiformes | |
Heptranchias howelli, the Sevengill shark, is a nektonic carnivore in the genus Heptranchias. It is an extinct species that ranged from 37 to 33 Ma.
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Fossil Records
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 Trelde Næs yielded a complete lower tooth, 17 incomplete lower teeth, and an unidentified broken tooth.
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 17.5 mm mesio-distally, 8.5 mm apico-basally and 4.5 mm labio-langually. The root height ranged from 3-5 millimeters.