''Eotitanosuchus'' ("dawn giant crocodile") is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

biarmosuchia Biarmosuchians are an extinct clade of non-mammalian synapsids from the Permian. They are the most basal group of the therapsids. All of them were moderately-sized, lightly-built carnivores, intermediate in form between basal sphenacodont " pelyc ...

therapsid Therapsida is a major group of eupelycosaurian synapsids that includes mammals, their ancestors and relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented more ...

s whose

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s were found in the town of Ochyor in

Perm Krai Perm Krai (russian: Пе́рмский край, r=Permsky kray, p=ˈpʲɛrmskʲɪj ˈkraj, ''Permsky krai'', , ''Perem lador'') is a federal subject of Russia (a krai) that came into existence on December 1, 2005 as a result of the 2004 re ...

Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eig ...

. It lived about 267 million

year A year or annus is the orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the hou ...

s ago. The only species is ''Eotitanosuchus olsoni''.

Description

''Eotitanosuchus'' is known from a single large skull without a lower jaw. The

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

was , but the overall length may have been over , possibly up to and more than in weight for adult specimens. Like '' Biarmosuchus tener'', it was primitive in that, though it was a predator, the temple opening behind the eye was small, giving it a weak

bite Biting is a common zoological behavior involving the active, rapid closing of the jaw around an object. This behavior is found in toothed animals such as mammals, reptiles, amphibians and fish, but can also exist in arthropods. Myocytic co ...

. The temple was, however, larger at the top than in other

ns.

Paleoecology

''Eotitanosuchus'' fossils were found in the

Perm Perm or PERM may refer to: Places *Perm, Russia, a city in Russia ** Permsky District, the district **Perm Krai, a federal subject of Russia since 2005 **Perm Oblast, a former federal subject of Russia 1938–2005 **Perm Governorate, an administra ...

(or Cis-Urals) region of Russia. ''Eotitanosuchus'' was without doubt a dominant animal of its environment. Found preserved in flood deposits (once coastal bogs) containing many skeletons of estemmenosuchids, it has been suggested that this large predator was an excellent swimmer, possibly semi-aquatic or frequenting marshy ground. This, however, is just speculation.

Classification

''Eotitanosuchus'' is often grouped with the Phthinosuchidae and the

Biarmosuchidae Biarmosuchidae is a family of biarmosuchian therapsids Therapsida is a major group of eupelycosaurian synapsids that includes mammals, their ancestors and relatives. Many of the traits today seen as unique to mammals had their origin with ...

. In fact, Ivakhnenko (1999) argues that '' Biarmosuchus tener'' and ''Eotitanosuchus olsoni'' are the same organism, which would eliminate the Eotitanosuchia as a separate taxon, though this conclusion does not seem to have been widely accepted. Regardless of the eventual outcome of this debate, Ivakhnenko's paper does seem to show that ''Eotitanosuchus'' is very similar to ''Biarmosuchus''. Further, given the rather close similarity between ''Eotitanosuchus'' and later therapsids, this observation supports the view that Biarmosuchia is paraphyletic. Others view ''Eotitanosuchus'' as quite distinct from other basal therapsids and perhaps closer to the

Gorgonopsia Gorgonopsia (from the Greek Gorgon, a mythological beast, and 'aspect') is an extinct clade of sabre-toothed therapsids from the Middle to Upper Permian roughly 265 to 252 million years ago. They are characterised by a long and narrow skull, a ...

but gorgonopsian specializations are either not present in ''Eotitanosuchus'' or, as is more often the case, the state of the characters is unknown. This genus is characterized by many primitive features of the septomaxilla, the postorbital, the parietal, the interparietal, the basioccipital, the quadrate rami of the pterygoid and the

vomer The vomer (; lat, vomer, lit=ploughshare) is one of the unpaired facial bones of the skull. It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right max ...

s of the skull. The length of the dorsal process of the

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...

(front jawbone) and the postorbital twisting (rear side of the skull) constitute specializations that indicate it is not a direct gorgonopsian ancestor. These features, however, are shared by the

anteosaur Anteosaurs are a group of large, primitive carnivorous dinocephalian therapsids with large canines and incisors and short limbs, that are known from the Middle Permian of South Africa, Russia, China, and Brazil. Some grew very large, with skulls ...

and biarmosuchid lineages.

References

* * * Patricia Vickers-Rich and Thomas H. Rich, ''

The Great Russian Dinosaurs ''The'' () is a grammatical article in English, denoting persons or things already mentioned, under discussion, implied or otherwise presumed familiar to listeners, readers, or speakers. It is the definite article in English. ''The'' is the m ...

'',

Gunter Graphics Gunter or Günter may refer to: * Gunter rig, a type of rig used in sailing, especially in small boats * Gunter Annex, Alabama, a United States Air Force installation * Gunter, Texas, city in the United States People Surname * Chris Gunter ...

, 1993, pg. 28.

External links

Eotitanosuchidae
at Kheper

at Palaeos * ttp://palaeos.com/vertebrates/therapsida/biarmosuchia.html#Biarmosuchia Therapsida: Biarmosuchiaat Palaeos Biarmosuchians Prehistoric therapsid genera Wordian genera Guadalupian synapsids of Europe Permian Russia Fossils of Russia Fossil taxa described in 1960 {{paleo-therapsid-stub

Description

Paleoecology

Classification

See also

References

External links