Otodus is an extinct, cosmopolitan 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".

Quick Facts Scientific classification, Type species ...

Otodus Temporal range: Paleocene–Pliocene, 65–4 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Reconstructed jaws of a Paleogene Otodus (O. obliquus)
Reconstructed jaws of a Neogene Otodus (O. megalodon)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Elasmobranchii
Subdivision:	Selachimorpha
Order:	Lamniformes
Family:	†Otodontidae
Genus:	†Otodus Agassiz, 1843
Type species
†Otodus obliquus Agassiz, 1838
Species[1][2]
†Otodus obliquus (type) †Otodus aksuaticus †Otodus auriculatus †Otodus sokolovi †Otodus angustidens †Otodus chubutensis †Otodus megalodon Species pending reassessment †Otodus debrayi †Otodus latidens †Otodus mediavus †Otodus minor †Otodus naidini †Otodus poseidoni †Otodus rondelettiformis
Synonyms[3]
Carcharocles? Hannibal & Jordan in Jordan, 1923

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All species are known from their fossilized teeth, and four of them (O. obliquus, O. auriculatus, O. angustidens and O. megalodon) are also known from their fossilized vertebral centra.^[4][5] 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.^[6][7]

Otodus had a worldwide distribution, as fossils have been excavated from Africa, Asia, Europe, North America, South America, Caribbean and Australia.^[6][15]

Otodus was likely among the apex predator of its time and commonly preyed upon fish, sea turtles, cetaceans (e.g. whales), and sirenids.^[16]

There is also potential evidence that Otodus hunted raptorial sperm whales; a tooth belonging to an undetermined 4 m (13 ft) long physeteroid closely resembling those of Acrophyseter discovered in the Nutrien Aurora Phosphate Mine in North Carolina suggests that a megalodon or O. chubutensis may have aimed for the head of the sperm whale in order to inflict a fatal bite, the resulting attack leaving distinctive bite marks on the tooth. While scavenging behavior cannot be ruled out as a possibility, the placement of the bite marks is more consistent with predatory attacks than feeding by scavenging, as the jaw is not a particularly nutritious area for a shark to feed or focus on. The fact that the bite marks were found on the tooth's roots further suggest that the shark broke the whale's jaw during the bite, suggesting the bite was extremely powerful. The fossil is also notable as it stands as the first known instance of an antagonistic interaction between a sperm whale and an otodontid shark recorded in the fossil record.^[17]

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.^[18] Scientists determined that Otodus evolved into the genus Carcharocles, given substantial fossil evidence in the form of transitional teeth.^[6][7] 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.^[6] 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.^[19]

• Prehistoric fish