Carcharocles angustidens

A collection of teeth from juvenile Carcharocles angustidens

***Carcharocles angustidens*** is a prehistoric megatoothed lamniform shark, which lived during the Oligocene and Miocene epochs about 33 to 22 million years ago. This shark is related to fellow extinct megatoothed sharks, such as Carcharocles auriculatus and *Carcharocles megalodon*.

## Fossils

As is the case with most extinct sharks, this species is mostly known from fossil teeth and some fossilized vertebral centra. Shark skeletons are composed of cartilage and not bone, and cartilage fossilizes but rarely. 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 centra. This unique 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, South America, Europe, Africa, New Zealand, Japan, and Australia.

## Size

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 m (31 ft) in length. This specimen had teeth measuring up to 9.87 cm (3.89 in) in diagonal length, and vertebral centra around 1.10 cm (0.43 in) in diameter. However, reports of larger *C. angustidens* fossils have been made. However, as with many fossils, the exact measurements of these purported specimens are hard to estimate.

## Paleoecology

*C. angustidens* was an apex predator and likely preyed upon penguins, fish, dolphins, and baleen whales. The hunting of baleen whales in particular, would be taken to extremes in its descendants, such as *C. megalodon*.

## Taxonomy

A Swiss naturalist, Louis Agassiz, first identified this shark as a species of genus *Carcharodon* 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*.

However, in 1987, shark expert H. Cappetta recognized the *C. auriculatus* - *C. megalodon* lineage and placed all related megatooth sharks along with these species in the genus *Carcharocles*. The complete *Otodus obliquus* to *C. megalodon* transition then became clear and has since gained the acceptance of many other experts with the passage of time. Within the *Carcharocles* lineage, *C. angustidens* is the species succeeding *C. sokolovi* and is followed by *C. chubutensis*.

In 2001, a discovery of the best preserved *Carcharocles angustidens* specimen to date by two scientists, Michael D. Gottfried and Robert Ewan Fordyce, has been presented by the team as evidence for close morphological ties with the extant great white shark, and the team argued that *Carcharocles angustidens*, along with all other related megatooth sharks, including *Carcharocles megalodon*, should be assigned to *Carcharodon* as was done before by Louis Agassiz, although this is not internationally accepted by the scientific community. Evidence at present points to the genera of *Carcharodon* and *Carcharocles* being separate lineages of lamniform sharks.