New Zealand white shark
Encyclopedia
Carcharocles angustidens is a prehistoric megatoothed shark, which lived during the Oligocene
and Miocene
epochs approximately about 35 to 22 million years ago. This shark is believed to be closely related to another extinct megatoothed shark, C. megalodon
. However, just as in the case of C. megalodon, the classification of this species is also under dispute.
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. 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
, South America
, Europe
, Africa
, New Zealand, Japan
, Australia
, and Malta
.
, Carcharodon carcharias. The well preserved specimen from New Zealand is estimated at 9.3 metres (31 ft) in length. 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
. However, there are reports of larger C. angustidens fossils.
and likely preyed upon penguins, fish
, dolphins, and baleen whales.
, 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.
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.
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
and Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
epochs approximately about 35 to 22 million years ago. This shark is believed to be closely related to another extinct megatoothed shark, C. megalodon
Megalodon
The megalodon and ὀδούς ) is an extinct species of shark that lived roughly from 28 to 1.5 million years ago, during the Cenozoic Era .The taxonomic assignment of C...
. 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 fossilFossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
teeth and some fossilized vertebral centra. Shark skeleton
Skeleton
The skeleton is the body part that forms the supporting structure of an organism. There are two different skeletal types: the exoskeleton, which is the stable outer shell of an organism, and the endoskeleton, which forms the support structure inside the body.In a figurative sense, skeleton can...
is composed of cartilage
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...
and not bone
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...
, 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
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, which comprises 165 associated teeth and about 35 associated vertebral centrum. 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
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, New Zealand, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, and Malta
Malta
Malta , officially known as the Republic of Malta , is a Southern European country consisting of an archipelago situated in the centre of the Mediterranean, south of Sicily, east of Tunisia and north of Libya, with Gibraltar to the west and Alexandria to the east.Malta covers just over in...
.
Size estimation
Like other known megatooth sharks, the fossils of C. angustidens indicate that it was considerably larger than the extant great white sharkGreat white shark
The great white shark, scientific name Carcharodon carcharias, also known as the great white, white pointer, white shark, or white death, is a large lamniform shark found in coastal surface waters in all major oceans. It is known for its size, with the largest individuals known to have approached...
, Carcharodon carcharias. The well preserved specimen from New Zealand is estimated at 9.3 metres (31 ft) in length. This specimen had teeth measuring up to 9.87 cm (3.9 inch) in diagonal
Diagonal
A diagonal is a line joining two nonconsecutive vertices of a polygon or polyhedron. Informally, any sloping line is called diagonal. The word "diagonal" derives from the Greek διαγώνιος , from dia- and gonia ; it was used by both Strabo and Euclid to refer to a line connecting two vertices of a...
length, and vertebral centra of around 1.10 cm (4.33 inch) in diameter
Diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints are on the circle. The diameters are the longest chords of the circle...
. However, there are reports of larger C. angustidens fossils.
Dentition
The dental formula for C. angustidens isDiet
C. angustidens was an apex predatorApex predator
Apex predators are predators that have no predators of their own, residing at the top of their food chain. Zoologists define predation as the killing and consumption of another organism...
and likely preyed upon penguins, fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, dolphins, and baleen whales.
Classification dispute
Even after decades of scrutinizing fossils, C. angustidens remains a disputed genus. A Swiss naturalist, Louis AgassizLouis Agassiz
Jean Louis Rodolphe Agassiz was a Swiss paleontologist, glaciologist, geologist and a prominent innovator in the study of the Earth's natural history. He grew up in Switzerland and became a professor of natural history at University of Neuchâtel...
, 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
Otodus obliquus
Otodus obliquus is an extinct mackerel shark which lived during the Paleocene and Eocene epochs, approximately about 60 to 37.5 million years ago.-Known physiology:This shark is known from the fossil teeth and fossilized vertebral centra...
to C. auriculatus and moved C. angustidens to genus Otodus. (See "external links" below)
However, in 1987, shark expert, H. Cappetta
Henri Cappetta
Henri Cappetta is a French ichthyologist specialist of sharks and rays paleontology.-External links:* *...
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.
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.
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.