Otodus

Otodus is an extinct genus of mackerel shark which lived from the Paleocene to the Pliocene epoch. The name Otodus comes from Ancient Greek ὠτ (ōt, meaning "ear") and ὀδούς (odoús, meaning "tooth") – thus, "ear-shaped tooth".

Otodus Temporal range: Paleocene–Pliocene PreꞒ Ꞓ O S D C P T J K Pg N
Otodus obliquus teeth from the Eocene near Khouribga, Morocco.
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Order:	Lamniformes
Family:	†Otodontidae
Genus:	†Otodus Agassiz, 1843
Species
†Otodus aksuaticus †Otodus sokolovi †Otodus auriculatus †Otodus angustidens †Otodus chubutensis †Otodus megalodon? †Otodus limhamnensis †Otodus minor †Otodus minor turkmenicus †Otodus naidini †Otodus obliquus †Otodus obliquus ajatensis †Otodus obliquus minor †Otodus obliquus mugodzharicus †Otodus poseidoni †Otodus poseidoni poseidoni †Otodus poseidoni turanensis †Otodus poseidoni ustyurtensis
Synonyms
Carcharocles? Hannibal & Jordan in Jordan, 1923

Anatomy

This shark is known from its fossilized teeth and vertebral centra.[1] Like other elasmobranchs, the skeleton of Otodus was composed of cartilage and not bone, resulting in relatively few preserved skeletal structures appearing within the fossil record. The teeth of this shark are large with triangular crown, smooth cutting edges, and visible cusps on the roots. Some Otodus teeth also show signs of evolving serrations.[1][2]

A lingual (tongue-side) view of a lateral O. obliquus.

Size estimation

The fossils of Otodus indicate that it was a very large macro-predatory shark.[2] The largest known teeth measure about 104 millimetres (4.1 in) in height.[3] The vertebral centrum of this shark are over 12.7 cm (5 inch) wide.[2] Scientists suggest that this shark at least reached 9.1 metres (30 ft) in total length (TL),[2] with a maximum length of 12.2 metres (40 ft).[4]

Distribution

Otodus had a worldwide distribution, as fossils have been excavated from Africa, Asia, Europe, and North America.[1]

Diet

Otodus likely preyed upon large bony fish, other sharks, and from the Eocene until the genus' extinction during the Miocene, marine mammals. It was among the top predators of its time.

Evolution

It is widely believed that the genus originates from a lineage of sharks belonging to the genus Cretalamna, due to strong similarities in tooth morphology.[5] Scientists determined that Otodus evolved into the genus Carcharocles, given substantial fossil evidence in the form of transitional teeth.[1][2] Some teeth have been excavated from the sediments of the Nanjemoy Formation in Maryland, USA, Ypres clay in Belgium, and western Kazakhstan, which are morphologically very similar to Otodus teeth but with lightly serrated cusplets and a serrated cutting edge. These transitional fossils suggest a worldwide evolutionary event, and support the theory that Otodus eventually evolved into Otodus aksuaticus and thus initiated the Carcharocles lineage.[1] A more recent study of Megalolamna's taxonomic relationships demonstrates the possibility that Otodus needs to include the species sometimes assigned to Carcharocles (i.e., the megatoothed lineage, including megalodon) in order to be monophyletic.[6]

See also

• Prehistoric fish

References

1. Bourdon, Jim, Otodus
2. Renz, Mark (2002), Megalodon: Hunting the Hunter, PaleoPress, pp. 26–30, ISBN 0-9719477-0-8
3. "Huge OTODUS OBLIQUUS shark tooth with pathology". Archived from the original on July 22, 2011. Retrieved May 21, 2011.
4. Gordon Hubbel (2006). "Virtual Tour of Private Shark Museum". Retrieved 2014-02-12.
5. Ebersole, Jun A.; Ehret, Dana J. (2018-01-08). "A new species of Cretalamna sensu stricto (Lamniformes, Otodontidae) from the Late Cretaceous (Santonian-Campanian) of Alabama, USA". PeerJ. 6: e4229. doi:10.7717/peerj.4229. ISSN 2167-8359. PMC 5764036. PMID 29333348.
6. Shimada, K.; Chandler, R. E.; Lam, O. L. T.; Tanaka, T.; Ward, D. J. (2016-10-03). "A new elusive otodontid shark (Lamniformes: Otodontidae) from the lower Miocene, and comments on the taxonomy of otodontid genera, including the 'megatoothed' clade". Historical Biology. 29 (5): 704–714. doi:10.1080/08912963.2016.1236795. ISSN 0891-2963.