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Eotitanosuchus - replica of skull by Gondwana Studios

The Eotitanosuchids were large to very large (upto 6 meters long, weights of upto 500 kg or more) preditory therapsids of the middle Permian ( link to palaeos com Wordian epoch). Like the Biarmosuchia they are rather poorly known, although they were probably more common than their few remains indicate. They seem to be more advanced than the Biarmosuchia in that the temporal opening behind the eye socket, although small, is still somewhat larger than the biarmosuchians, being expanded in the upper rear (posterodorsal) margin, allowing the area of attachment of the adductor muscles that closed the lower jaw (Musc. adductor mandibulae externus) to be visible from the dorsal (top) view looking down. Hence the Eotitanosuchian bite was stronger and more efficient than the Biarmosuchian bite, and tended more towards the later therapsid condition.

For this reason paleontologists see the the Eotitanosuchids as transitional between the Biarmosuchids and the higher Therapsids. They may indeed be so, but I think it is just as - if not more - likely that features of a larger temporal opening and hence increased muscle mass and biting power evolved simultaneously, among a number of early therapsid groups, due to intense competition for food and other resources. One must be very wary in applying cladistic methodology on characteristics that are likely to evolve simultaneously among many competing lineages.

It is interesting that in other respects the Eotitanosuchians are more primitive - they were the least modified in their jaw apparatus from their sphenacodontid ancestry and appear to have lacked a key theriodont feature-the streptostylic (movable) quadrate.

Although often grouped with the Phthinosuchidae and the Biarmosachidae, Eotitanosuchus is quite distinct from both and may be closer to the Gorgonopsia. However, Gorgonopsian specialisations are either not present in Entitanosuchus or, as is more often the case, the state of the characters is unknown. This genus is characterised by many primitive features of the septomaxillary, the postorbital, the parietal, the interparietal, the basioccipital, the quadrate rami of the pterygoid and the vomers of the skull. The length of the dorsal process of the premaxillary (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 brithopodid and biarmosuchid lineages.

The Eotitanosuchids can thus be best understood as one of a number of lineages of competing early therapsids that flourished during link to palaeos com Middle Permian time.

Family Eotitanosuchidae Chudinov 1960

Ecological niche/Guild: medium-sized to very large to terrestrial (and semi-aquatic?) carnivores
Modern equivalent: canid???... crocodilian???
Time: link to palaeos com middle Permian (late? Roadian or early link to palaeos com Wordian epoch)
Distribution: although so far fossil remains are known only from eastern Russia it is likely these animals had a much wider, probably worldwide ( link to palaeos com Pangea) distribution
preferred food: other link to palaeos com tetrapods, large freshwater fish?
length: about 2 to 6 meters long (skull: 35 cm to upto 1 meter)
weight: about 30 kg to 600 kg or more
Metabolism: partially endothermic and gigantotherms (Homeotherms)
Predators: none (top of food chain)
Ancestor: Basal Therapsid (proto-Biarmosuchian ancestor?)
Replaced: Large Sphenacodontids
Replaced by: Brithopodids
Descendents: None - although proto-Eotitanosuchids may or may not have given rise to Gorgonopsid and/or Brithopidids
Taxonomic status - Monogeneric/monospecific? Family

List of genera

Until recently only two genera - each of one species, are recorded - Eotitanosuchus and Ivantosaurus. The latter is known from only two jaw fragments, and would seem to be very similiar to Eotitanosuchus. Personally I think it is unwise to erect a new genus on fragmentary material, and it is quite likely that this is just another species of Eotitanosuchus. L. P. Tatarinov, of the Paleontological Institute, Russian Academy of Sciences, has recently described a new species and genus of eotitanosuchid

Genus Eotitanosuchus Chudinov 1960
Meaning of name: "Dawn giant crocodile"
Type species: E. olsoni Chudinov 1960
Diagnosis: Snout long and high. Large orbit. Interorbital roof narrow. Occiput high. Step in the alveolar border. Lacrymal high and long. Vomers fusing.

Eotitanosuchus olsoni Chudinov 1960

Locality: Echovo locality, Ocher Province, Perm Region, eastern European Russia
Age Upper Kazanian, Late Permian, approx. 267 million years ago link to palaeos com Wordian epoch).
size: skull: 35 cm, overall length probably about 2 meters or more

The holotype is a crushed and deformed skull. Additional skull and skeletal material is known. A lot of this is juvenile material, such as the famous 35 cm long skull displayed in The Russian Dinosaur Exposition and shown here. An adult skull would likely reach about 1 metre in length, which would give an overall length of some 6 meters. There are 8 or 9 small and flattened postcanines in the jaw.

Eotitanosuchus is found preserved in flood deposits (once coastal bogs) containing many skeletons of estemmenosuchids, and it is likely that this large predators was an excellent swimmer, possibly semi-aquatic or frequenting marshy ground. Ther legs are quite long, and the animals were probably quite agile in spite of their size

Ivantosaurus ensifer Chudinov 1983 ? = Eotitanosuchus ensifer (Chudinov)

Locality: Echovo locality, Ocher Province, Perm Region, eastern European Russia
Age Upper Kazanian, Late Permian, approx. 267 million years ago link to palaeos com Wordian epoch)).
Holotype and only known material: Maxillary and quadrate found in association and in their respective natural position

Probably a giant individual of Eotitanosuchus (if E. olsoni is a juvenile this would therefore be a large adult), although it may or may not be a different species to E. olsoni. This is a very large animal (legth would have been around 6 meters). Maxillary short and high. Two upper canines, long, and with their axis inclined forward. It is not clear if one of the canines is a replacement tooth. Sigogneau-Russell (p.30) seems to think this is unlikely, which would make this a quite different animal to Eotitanosuchus. Personally I think (as with the therocephalian "family" Lycosuchidae) that one of these are replacement canines. As far as I am aware there is no known animal living or extinct with two sets of canines (it would be a very inefficient chewing mechanism)

Kamagorgon ulanovi Tatarinov 1999

Locality: Sokol locality, Udmurtia, Western part of the Middle Urals, Perm region, Russia
Age Upper Kazanian, Late Permian, approx. 267 million years ago link to palaeos com Wordian epoch)).
material: Based on an incomplete skull

The snout is relatively short, the canines are massive and long, the parietals are thickened, and the mandibular symphysis is extremely high. The palatal teeth cover the pterygoids and palatines and are not concentrated on special bony tubercles.

systematics note: In a revison of the therapsids of the Ezhovo locality, Dr M. F. Ivakhnenko, argues that Eotitanosuchus olsoni, Biarmosuchus tener, and Ivantosaurus ensifer are synonyms. However whilst the first and last species are quite possibly the same the synonymising of Eotitanosuchus with Biarmosuchus is more controversial. He also includes the family Eotitanosuchidae as a member of the order Titanosuchia, superorder Dinocephalia. I myself would consider the Dinocephalian an order (it is traditionally rated as suborder or even infra-order, but generally the Linnean hierarchy is being discarded by Wikipedia link paleontolgists in the West, although still retained by Russian and perhaps also continental European workers)

some printed references some Links and References Web links

printed referenceDenise Sigogneau-Russell, "Theriodontia I - Phthinosuchia, Biarmosuchia, Eotitanosuchia, Gorgonopsia" Part 17 B I, Encyclopedia of Paleoherpetology, Gutsav Fischer Verlag, Stuttgart and New York, 1989

printed referencePeter K. Chudinov, "New Facts about the Fauna of the Upper Permian of the USSR", Journal of Geology, 1965, 73:117-30

printed referenceEverett C. Olson, "Late Permian Terrestrial Vertebrates, USA and USSR", Transactions of the American Philosophical Society, Philadelphia, vol 52 part 2, 1962

web pagephotographsEotitanosuchus

web pagephotographsEotitanosuchus olsoni - same content as preceeding page, but bigger photo

web pagephotographsStars of the Show - includes Eotitanosuchus

web pageL. P. Tatarinov, A New Eotitanosuchid (Reptilia, Therapsida) from the Kazanian Stage (Upper Permian) of Udmurtia Paleonotological Journal - Vol. 33, No. 6, 1999

web pageM. F. Ivakhnenko, Biarmosuches from the Ocher Faunal Assemblage of Eastern Europe, Paleonotological Journal - Vol. 33, No. 3, 1999

link to palaeos com Permian Period Therapsida

link to palaeos com Palaeos link to palaeos com Palaeos Page (incorporates some of this material, plus a lot of additional material)

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Palaeo index page
Therapsida main page

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page by M.Alan Kazlev
page uploaded 8 August 2000. Reposted and last modified 1 September 2005, links updated 16 January 2010