Euthecodon
Encyclopedia
Euthecodon is an extinct genus
of longirostrine crocodyline
crocodilia
n. It was common throughout much of Africa
during the Neogene
, with fossil
s being especially common in Kenya
. It existed from the Early Miocene
to the Early Pleistocene
.
, was estimated by skull length to have been around 10m long. It had a narrow rostrum
that was unusually elongate with deeply scalloped dorsal margins. The skull table, however, was proportionally small and is almost square in shape. The jaws were lined with isodont, or slender, similarly sized and shaped, teeth. Unlike nearly all other crocodilians, Euthecodon possessed only four premaxilla
ry teeth. Because they are sharp and bicarinate, they are believed to have been an adaptation for a piscivorous feeding habit
, or a diet that included fish.
is a member. These specimens were described from the Pliocene
Omo Group in Ethiopia
. The genus Euthecodon was first named in 1920 on the basis of material found from Wadi Natrun, Egypt
. This material was believed to have belonged to the same species as the specimens from Ethiopia, yet it appeared to be distinct from the genus Tomistoma. As a result, the material from Ethiopia was reassigned to the new genus along with the material from Egypt, with the species being named E. nitriae.
A new species, named E. brumpti, was found from Lothagam
, Kenya and can be distinguished from E. nitriae by skull and rostral proportions as well as tooth count. E. brumpti is one of the most common fossil crocodylians found in the Turkana Basin, along with crocodiles referred to Rimasuchus lloydi
. A complete articulated skull and mandible referrable to E. brumpti was found in situ
from the Kaiyumung Member of the Nachukui Formation in Lothagam in 1992.
A shorter snouted species named E. arambourgi has been found from early Miocene deposits in Gebel Zelten, Libya
. Classification of specimens from several localities across Africa are indeterminant at the species level, with material being found from the Sahabi Formation in Libya of early Pliocene age, the Victoria Basin
strata of Rusinga Island
of early Miocene age, early Miocene deposits in Ombo
, Kenya, and possibly the Albertine Rift sediments of the Congo
of early Miocene age.
crocodilian. It has even been suggested to be a direct offshoot of Eogavialis
. However, it is now thought to be a crocodylid, having been allied with Rimasuchus
, Osteolaemus, and Voay
in the past.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of longirostrine crocodyline
Crocodile
A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...
crocodilia
Crocodilia
Crocodilia is an order of large reptiles that appeared about 84 million years ago in the late Cretaceous Period . They are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria...
n. It was common throughout much of 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...
during the Neogene
Neogene
The Neogene is a geologic period and system in the International Commission on Stratigraphy Geologic Timescale starting 23.03 ± 0.05 million years ago and ending 2.588 million years ago...
, with fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s being especially common in Kenya
Kenya
Kenya , officially known as the Republic of Kenya, is a country in East Africa that lies on the equator, with the Indian Ocean to its south-east...
. It existed from the Early Miocene
Early Miocene
The Early Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages....
to the Early Pleistocene
Early Pleistocene
Calabrian is a subdivision of the Pleistocene Epoch of the Geologic time scale. ~1.8 Ma.—781,000 years ago ± 5,000 years, a period of ~.The end of the stage is defined by the last magnetic pole reversal and plunge in to an ice age and global drying possibly colder and drier than the late Miocene ...
.
Description
Euthecodon was large for a crocodilian. One specimen, LT 26306, found from the Turkana BasinLake Turkana
Lake Turkana , formerly known as Lake Rudolf, is a lake in the Great Rift Valley in Kenya, with its far northern end crossing into Ethiopia. It is the world's largest permanent desert lake and the world's largest alkaline lake...
, was estimated by skull length to have been around 10m long. It had a narrow rostrum
Rostrum (anatomy)
The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....
that was unusually elongate with deeply scalloped dorsal margins. The skull table, however, was proportionally small and is almost square in shape. The jaws were lined with isodont, or slender, similarly sized and shaped, teeth. Unlike nearly all other crocodilians, Euthecodon possessed only four premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
ry teeth. Because they are sharp and bicarinate, they are believed to have been an adaptation for a piscivorous feeding habit
Piscivore
A piscivore is a carnivorous animal which eats primarily fish. Piscivory was the diet of early tetrapods , insectivory came next, then in time reptiles added herbivory....
, or a diet that included fish.
Discovery and species
Collected material now known to be from Euthecodon was initially placed in the genus Tomistoma, of which the modern false gharialFalse gharial
The false gharial , also known as the Malayan gharial, false gavial, or Tomistoma is a freshwater crocodile of the Crocodylidae family with a very thin and elongated snout...
is a member. These specimens were described from the Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
Omo Group in Ethiopia
Ethiopia
Ethiopia , officially known as the Federal Democratic Republic of Ethiopia, is a country located in the Horn of Africa. It is the second-most populous nation in Africa, with over 82 million inhabitants, and the tenth-largest by area, occupying 1,100,000 km2...
. The genus Euthecodon was first named in 1920 on the basis of material found from Wadi Natrun, Egypt
Egypt
Egypt , officially the Arab Republic of Egypt, Arabic: , is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Southwest Asia. Egypt is thus a transcontinental country, and a major power in Africa, the Mediterranean Basin, the Middle East and the Muslim world...
. This material was believed to have belonged to the same species as the specimens from Ethiopia, yet it appeared to be distinct from the genus Tomistoma. As a result, the material from Ethiopia was reassigned to the new genus along with the material from Egypt, with the species being named E. nitriae.
A new species, named E. brumpti, was found from Lothagam
Lothagam
The Lothagam is a palaeontological formation located in Kenya. It dates to the Miocene-Pliocene period.It is located near the southwestern shores of Lake Turkana, 55 kilometres from Kanapoi...
, Kenya and can be distinguished from E. nitriae by skull and rostral proportions as well as tooth count. E. brumpti is one of the most common fossil crocodylians found in the Turkana Basin, along with crocodiles referred to Rimasuchus lloydi
Rimasuchus
Rimasuchus is an extinct genus of crocodile from the Neogene period of Africa and the Middle East. Its name comes from the Latin words rima, meaning "crack" and suchus, which means "crocodile"...
. A complete articulated skull and mandible referrable to E. brumpti was found in situ
In situ
In situ is a Latin phrase which translated literally as 'In position'. It is used in many different contexts.-Aerospace:In the aerospace industry, equipment on board aircraft must be tested in situ, or in place, to confirm everything functions properly as a system. Individually, each piece may...
from the Kaiyumung Member of the Nachukui Formation in Lothagam in 1992.
A shorter snouted species named E. arambourgi has been found from early Miocene deposits in Gebel Zelten, Libya
Libya
Libya is an African country in the Maghreb region of North Africa bordered by the Mediterranean Sea to the north, Egypt to the east, Sudan to the southeast, Chad and Niger to the south, and Algeria and Tunisia to the west....
. Classification of specimens from several localities across Africa are indeterminant at the species level, with material being found from the Sahabi Formation in Libya of early Pliocene age, the Victoria Basin
Lake Victoria
Lake Victoria is one of the African Great Lakes. The lake was named for Queen Victoria of the United Kingdom, by John Hanning Speke, the first European to discover this lake....
strata of Rusinga Island
Rusinga Island
Rusinga Island, with an elongated shape approx. 10 miles from end to end and 3 miles at its widest point, lies in the eastern part of Lake Victoria at the mouth of the Winam Gulf...
of early Miocene age, early Miocene deposits in Ombo
Ombo
Ombo is the largest island in the Ryfylke region on the south-west coast of Norway. It is part of the county of Rogaland. It is divided between the two municipalities of Hjelmeland and Finnøy....
, Kenya, and possibly the Albertine Rift sediments of the Congo
Congo River
The Congo River is a river in Africa, and is the deepest river in the world, with measured depths in excess of . It is the second largest river in the world by volume of water discharged, though it has only one-fifth the volume of the world's largest river, the Amazon...
of early Miocene age.
Phylogeny
Euthecodon was originally considered a tomistomineTomistominae
Tomistominae is a subfamily of crocodylians that includes one living species, the False gharial. Many more extinct species are known, extending the range of the subfamily back to the Eocene epoch...
crocodilian. It has even been suggested to be a direct offshoot of Eogavialis
Eogavialis
Eogavialis is an extinct gavialoid. It superficially resembles Tomistoma schlegelii, the extant false gharial, and consequently material from the genus was originally referred to Tomistoma...
. However, it is now thought to be a crocodylid, having been allied with Rimasuchus
Rimasuchus
Rimasuchus is an extinct genus of crocodile from the Neogene period of Africa and the Middle East. Its name comes from the Latin words rima, meaning "crack" and suchus, which means "crocodile"...
, Osteolaemus, and Voay
Voay
Voay is an extinct genus of crocodylid crocodilian. Numerous subfossils have been found from Madagascar, including complete skulls as well as vertebrae and osteoderms from such places as Ambolisatra and Antsirabe. The genus is thought to have become extinct relatively recently during the Holocene...
in the past.
External links
- Euthecodon in the Paleobiology DatabasePaleobiology Database' is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms.-History:The Paleobiology Database was founded in 2000. It has been funded by the National Science Foundation and the Australian Research Council...