Carcharocles angustidens

Carcharocles angustidens Temporal range: Oligocene - Miocene
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Subclass:	Elasmobranchii
Order:	Lamniformes
Family:	Disputed; either Lamnidae or Otodontidae
Genus:	Disputed; either Carcharodon or Carcharocles
Species:	C. angustidens
Binomial name
Disputed; either Carcharodon angustidens or Carcharocles angustidens For Carcharodon angustidens, Agassiz, 1843

Carcharocles angustidens is a prehistoric megatoothed shark, which lived during the Oligocene and Miocene epochs approximately about 35 to 22 million years ago.^[1] This shark is believed to be closely related to another extinct megatoothed shark, C. megalodon.^[1] However, just as in the case of C. megalodon, the classification of this species is also under dispute.

Fossil record

As is the case with most extinct sharks, this species is also known from fossil teeth and some fossilized vertebral centra. Shark skeleton is composed of cartilage and not bone, and cartilage rarely gets fossilized. Hence, fossils of C. angustidens are generally poorly preserved. To date, the best preserved specimen of this species have been excavated from New Zealand, which comprises 165 associated teeth and about 35 associated vertebral centrum.^[2] This specimen is around 26 million years old. C. angustidens teeth are noted for their triangular crowns and small side cusps that are fully serrated. The serrations are very sharp and very well pronounced. C. angustidens was a widely distributed species with fossils found in North America,^[2] South America,^[2] Europe,^[2] Africa,^[2] New Zealand,^[2] Japan,^[2] Australia,^[2] and Malta.

Size estimation

Like other known megatooth sharks, the fossils of C. angustidens indicate that it was considerably larger than the extant great white shark, Carcharodon carcharias. The well preserved specimen from New Zealand is estimated at 9.3 metres (31 ft) in length.^[2] This specimen had teeth measuring up to 9.87 cm (3.9 inch) in diagonal length, and vertebral centra of around 1.10 cm (4.33 inch) in diameter.^[2] However, there are reports of larger C. angustidens fossils.^[3]

Dentition

The dental formula for C. angustidens is $Upper: 2.1.5.4, lower: 3.0.6.3$

Diet

C. angustidens was an apex predator and likely preyed upon penguins, fish, dolphins, and baleen whales.

Classification dispute

Even after decades of scrutinizing fossils, C. angustidens remains a disputed genus.^[2] A Swiss naturalist, Louis Agassiz, first identified this shark as a species of Carcharodon genus, in 1835.

In 1964, shark expert, L. S. Glikman recognized the transition of Otodus obliquus to C. auriculatus and moved C. angustidens to genus Otodus. (See "external links" below)

However, in 1987, shark expert, H. Cappetta realized the C. auriculatus - C. megalodon lineage and placed all related megatooth sharks along with these species in the genus, Carcharocles. For the first time, the complete Otodus obliquus to C. megalodon transition became clear and since have gained acceptance of many other experts with passage of time. (See "external links" below)

Within the Carcharocles lineage; C. angustidens is the succeeding species of C. sokolovi and is exceeded by C. chubutensis.^[1]

However, in 2001, a discovery of a best preserved C. angustidens specimen to date by two scientists, M. D. Gottfried, and R. Ewan Fordyce, have been presented by the team as an evidence for its close morphological ties with the extant great white shark and the team argued that C. angustidens along with all other related megatooth sharks (including C. megalodon) should be assigned to Carcharodon as done before by Louis Agassiz.^[2]

See also

• Prehistoric fish
• Largest prehistoric organisms

Sharks portal

References

1. ^ ^{a b c} Renz, Mark (2002). Megalodon: Hunting the Hunter. PaleoPress. pp. 26–30. ISBN 0-9719477-0-8 
2. ^ ^{a b c d e f g h i j k l} Gottfried M.D., Fordyce R.E (2001). "An Associated Specimen of CARCHARODON ANGUSTIDENS (CHONDRICHTHYES, LAMNIDAE) From the LATE OLIGOCENE of NEW ZEALAND, with comments on CARCHARODON Interrelationships". Journal of Vertebrate Paleontology 21 (4): 730–739. doi:10.1671/0272-4634(2001)021[0730:AASOCA]2.0.CO;2. 
3. ^ C. angustidens fossils from Black River Fossils

General references

• Glikman, L.S., 1980.. Evolution of Cretaceous and Caenozoic Lamnoid Sharks:3-247, pls.1-33. Moscow.
• Jordan, D.S. & Hannibal, H., 1923. Fossil Sharks and Rays of the Pacific Slope of North America. Bulletin of the Southern California Academy of Sciences, 22:27-63, plates 1-9.

External links

• A large extinct white shark: Carcharodon angustidens from New Zealand Oligocene rocks.
• Carcharocles: Extinct Megatoothed shark