Otodus auriculatus

Otodus auriculatus^[1] is an extinct species of large shark in the genus Otodus of the family Otodontidae and is a predecessor of the megalodon. The largest individuals were about 9.5 metres (31 ft) long and teeth can reach up to 130 millimetres (5.1 in). Its teeth were the first in the genus Otodus to have both coarse serrations on the cutting edge and lateral cusplets.

Otodus auriculatus Temporal range: Late Eocene-Early Oligocene ~35–25 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Teeth from Craven County, North Carolina
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Elasmobranchii
Division:	Selachii
Order:	Lamniformes
Family:	†Otodontidae
Genus:	†Otodus
Species:	†O. auriculatus
Binomial name
†Otodus auriculatus Blainville, 1818
Subspecies
O. a. disauris (Agassiz, 1835) O. a. auriculatus? (Blainville, 1818)
Synonyms
Otodus subserratus Carcharocles ariculatus Carcharocles auriculata Carcharodon auriculatus

Assignment to the genus Carcharocles rather than Otodus

Megachasma alisonae and Otodus auriculatus

It is known that there is at least one genus in the family Otodontidae, that being Otodus. But the names and number of the genera in Otodontidae is controversial and the family's accepted phylogeny varies among paleontologists in different parts of the world. In the US and Britain the most widespread genus name for otodontids with serrated teeth is Carcharocles, and the owners of unserrated ones Otodus. In countries of the former USSR, like Ukraine or Russia, all of these genera were attributed to Otodus, because scientists like Zhelezko and Kozlov^[2] thought that the absence or presence of tooth serrations is not enough to place these sharks in different taxa.

Size

O. auriculatus was a large lamniform shark, with the largest individuals reaching a body length of 9.5 metres (31 ft).^[3] The tooth length of O. auriculatus is relatively large - from 25 to 114 millimetres (0.98 to 4.49 in).^[4] However, it is smaller than that of megalodon and Otodus angustidens; the tooth length of O. megalodon is 38 to 178 millimetres (1.5 to 7.0 in) and O. angustidens 25 to 117 millimetres (0.98 to 4.61 in).^[4] Smaller individuals were about 4 metres (13 ft) long.^[5]

Distribution

Most O. auriculatus teeth come from South Carolina and North Carolina.^[4] However, many Eocene shark teeth are known from Khouribga Plateau, in Morocco and Seymour Island, in Antarctica. Fossil teeth have also been found in the United Kingdom and Kazakhstan, and the shark enjoyed a fairly global distribution.^[6] A single tooth is known from Egypt.^[7]