| Heptranchias howelli | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Order: | Hexanchiformes |
| Family: | Hexanchidae |
| Genus: | Heptranchias |
| Species: | H. howelli |
| Binomial name | |
| Heptranchias howelli Reed, 1946 [1] | |
| Synonyms | |
| |
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. [3]
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. [4] A 2015 study in Trelde Næs yielded a complete lower tooth, 17 incomplete lower teeth, and an unidentified broken tooth. [5]
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. [4] The cusps are inclined at about a 45 degree angle distally.
The largest tooth found in Trelde Naes was 17.5 millimetres (0.69 in) mesio-distally, 8.5 millimetres (0.33 in) apico-basally and 4.5 millimetres (0.18 in) labio-langually. The root height ranged from 3 to 5 millimetres (0.12 to 0.20 in). [5]
Fossils of Heptranchias howelli have been found in: [3]
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