''Notidanodon'' 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 ascribed to this genus are known from the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

and

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

periods. Recently, the genus underwent a major revision and was split into two after the erection of ''Xampylodon'' to accommodate the species ''X. dentatus'', ''X. loozi'', and ''X. brotzeni''. The genus is now known only from New Zealand, Antarctica, Africa, and South America.

Species

The earliest occurrences of attributed specimens are from the

Tithonian In the geological timescale, the Tithonian is the latest age (geology), age of the Late Jurassic Epoch and the uppermost stage (stratigraphy), stage of the Upper Jurassic Series. It spans the time between 149.2 ±0.7 annum, Ma and 143.1 ±0.6 (mi ...

of New Zealand, and the latest are from the

Maastrichtian The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (geology), age (uppermost stage (stratigraphy), stage) of the Late Cretaceous epoch (geology), Epoch or Upper Cretaceous series (s ...

of Antarctica. Currently, only two

Mesozoic The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...

species, ''Notidanodon pectinatus'' and ''Notidanodon lanceolatus'', are attributed to the genus. A putative third species, ''Notidanodon antarcti'', appears only in the caption of Figure 2 in Grande and Chatterjee (1987), but the same material was treated as ''Notidanodon'' sp. in the main text. Later, ''N. antarcti'' was considered a ''nomen dubium'' and regarded as a junior synonym of ''Notidanodon pectinatus''.

References

Prehistoric shark genera Hexanchidae Cretaceous sharks {{paleo-shark-stub