''Xampylodon'' is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

cow shark Cow sharks are a shark family, the Hexanchidae, characterized by an additional pair or pairs of gill slits. Its species are placed within the 11 genera: '' Gladioserratus'', '' Heptranchias'', '' Hexanchus'', ''Notidanodon'', '' Notorynchus'', '' ...

. Fossils assigned to this genus are known from the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

and early

Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

. ''Xampylodon'' was erected in 2021 after a revision on the taxonomy of hexanchid fossil teeth, and includes four species (''X. dentatus'', ''X. loozi'',''X. brotzeni'', and ''X. diastemacron''), most of them previously included in ''Notidanodon''.

Morphology

''Xampylodon'' is known exclusively from isolated teeth. These teeth have a unique morphology (especially the saw-like teeth from the lower jaw). ''Xampylodon'' teeth are characterized by having an acrocone (or main cusp) and cusplets bent distally, with a convex mesial cutting edge. The mesial cusplets are much smaller than the distal ones. The root is very deep, unlike the condition observed in ''Notidanodon''. ''Xampylodon'' species differ from each other in aspects such as size, the number and shape of the mesial cusplets, the orientation of the acrocone, and the presence of a gap between cusplets.

Species

References

Prehistoric shark genera Fossil taxa described in 2021 Hexanchidae Cretaceous sharks {{paleo-shark-stub