Hexanchus microdon

Hexanchus microdon Temporal range: Cenomanian–Danian PreꞒ Ꞓ O S D C P T J K Pg N Possible Aptian to Ypresian record
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Elasmobranchii
Division:	Selachii
Order:	Hexanchiformes
Family:	Hexanchidae
Genus:	Hexanchus
Species:	†H. microdon
Binomial name
†Hexanchus microdon (Agassiz, 1835)
Synonyms
Notidanus microdon Agassiz, 1835

Hexanchus microdon is an extinct species of sixgill shark that was found worldwide from the mid-Cretaceous to the Paleocene.

Taxonomy

One of the earliest known sixgill sharks in the fossil record, it was described by Louis Agassiz in 1835, but was originally identified by Gideon Mantell in 1822 as a Squalus tooth. The name has been often applied to any shark teeth from the Late Cretaceous of Europe with a small morphology reminiscent of the modern bigeye sixgill shark, and taxonomic revisions are likely necessary, especially due to the non-informative nature of the type specimens. Teeth from as late as the Early Eocene of Morocco have also been referred to this species, even while concurrent Hexanchus species in other regions are known by different names. In contrast, at some areas such as the Late Cretaceous of Germany, it appears to be the only Hexanchus species confidently present. Hexanchus gracilis, a species known from complete fossil skeletons from the Sahel Alma site in Lebanon, may be potentially synonymous with it.

Occurrences

Based on the Paleobiology Database:

References