Palaeos		Therapsida
Vertebrates		Biarmosuchia: Biarmosuchidae / Eotitanosuchidae

Therapsida: Biarmosuchia: Biarmosuchidae / Eotitanosuchidae

SYNAPSIDA
|
THERAPSIDA
`-Raranimus
  |--Biarmosuchia
  |  |--Biarmosuchidae
  |  `--Ictidorhinidae
  |     `--Burnetiamorpha
  `-+--Eotitanosuchia
    `-Eutherapsida
      |--Dinocephalia
      |  |--Anteosauria
      |  `--Tapinocephalia
      `--+--Anomodontia
         |  |--Venyukovioidea
         |  `--Dicynodontia   
         `--Theriodontia
            |--Gorgonopsia
            `--+--Therocephalia
               `--CYNODONTIA

Taxa on This Page

1. Biarmosuchidae X
2. Biarmosuchus X
3. Eotitanosuchia X
4. Eotitanosuchus X
5. Ivantosaurus X
6. Kamagorgon X

Biarmosuchia: Biarmosuchidae / Eotitanosuchidae

Ivantosaurus ensifer - the largest carnivore of the Permian period
life reconstruction artwork by Dmitry Bogdanov - Wikipedia

Eotitanosuchus - illustration copyright © Satoshi Kawasaki
Suborder "Biarmosuchia" Family Eotitanosuchidae (=Biarmosuchidae) Species Biarmosuchus tener Chudinov 1960 Eotitanosuchus olsoni Chudinov 1960 Ivantosaurus ensifer Chudinov 1983 Horizon: Upper Kazanian or Lower Tartarian Locality: Echovo locality, Ocher Province, Perm Region, Russia Possible age: Late Roadian/early Wordian Length (skull): 15 cm (immature) to 21 cm 35 cm about a meter? Length (total): 1.5 meters c. 2.5 meters over 6 meters? Size: large dog   large bull Diet: small tetrapods tetrapods large tetrapods
Eotitanosuchus attacks Estemmenosuchus; illustration © Seiji Yamamoto	Biarmosuchus; authorship of this illustration unknown Comments: The Eotitanosuchids constitute an important element of the Kazanian fauna; representing a good ancestral type that other, more advanced, therapsids would have evolved from. They are thought to have been semi-aquatic. Three monospecific genera - Biarmosuchus, Eotitanosuchus, and Ivantosaurus - are known from the Ocher locality, differing dramatically in size. Ivakhnenko 1999 argues that these represent different growth stages of the same animal (Ivakhnenko 1999). Personally I think it is more likely that these represent three different but closely related forms (belonging to the same family, perhaps even the same genus), representing different predator size guilds, with the smallest (Biarmosuchus) being the most common, and - in keeping with the nature of trophic webs - the largest, Ivantosaurus, being the rarest (it is known only from a fragment of maxilla that includes a very large canine tooth). Regardless of whether these are related but distinct species, or growth stages of the same species, it seems that these two forms are more similar than have usually been acknowledged. Thus the illustrations here can equally apply to all three.
Biarmosuchus, known from two skulls and postcrania, was a medium-sized predator, similar in size to a large dog. It was a lightly built, probably agile animal that would have fed on smaller tetrapods. Their legs are quite long, and the animals were probably quite agile in spite of their size. Eotitanosuchus known from a single large skull without a lower jaw, 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. The name means "Dawn giant crocodile", which is a bit misleading because although a large preditor it was not huge. A catalogue of a Russian dinosaur exhibition (Vickers-Rich and Rich, 1993) states that the oft-illustratred skull (about 35 cm long) is from a juvenile, an adult has a skull about 1 meter long. I have not found any other information on this, apart from the reference to the eotitanosuchid Ivantosaurus ensifer, known from a jaw fragment from the same locality (Sigogneau-Russell 1989 pp.29-30). So It seems what is being stated here is Ivakhnenko's thesis that this is the adult form of Eotitanosuchus/Biarmosuchus. It is just as likely that this was a distinct animal, and that these were three related forms of different sizes. In any case, assuming that the rest of the creature was in proportion, Ivantosaurus would have been the largest carnivorous therapsid known, exceeding in size even the largest Late Wordian/early Capitanian anteosaurs. References: Sigogneau-Russell 1989, Ivakhnenko, 1999, Vickers-Rich and Rich, 1993 (revised MAK091114, 120127)

Biarmosuchidae: Biarmosuchus

Range: Middle Permian of Russia

Phylogeny: Biarmosuchia: Ictidorhinidae + *.

Characters: Long dorsal process of premaxilla [S89]; very narrow interorbital roof (?!) [S89]; short lateral postorbital bone, not reaching the level of the ventral border of the orbit [S89]; paroccipital process reaches quadrate [S89]; parasphenoid keeled ventrally [S89]; long palatal dentigerous tuberosities [S89]; mandibular symphysis not sloping [S89]; incisors perhaps without a heel(?) [S89]; short cervical vertebrae, but longer than dorsals, and with a ventral keel [S89]; long neural apophyses [S89]; slightly divergent zygapophyses [S89]; interclavicle very wide anteriorly [S89]; humerus with feeble torsion and with entepicondylar foramen [S89]; humerus wide distally [S89]; ilia widen only slightly anteriorly (means ilia diverge slightly? bones transversely broader? or what?) [S89]; pubis very strongly developed [S89]; slender limbs [S89]; phalangeal formula 23454 [S89].

Links: Gondwana Studios; Lecture 03 - Cont. Drift (but where is he getting this information?); synapsurv.PDF; THE FOSSIL RECORD; therapsid3a. 

References: Sigogneau-Russell (1989) [S89].  ATW030224.

Eotitanosuchia: Eotitanosuchus, Ivantosaurus, Kamagorgon. 

Range: Middle Permian ( (Late Roadian/early Wordian).) of Russia. 

Phylogeny: Therapsida::::: Eutherapsida + *. 

Characters: Large (2.5 meters (possibly upto 6m?), carnivorous forms; incisors & postcanines small; canines very large; no precanines; vomers incompletely fused; pterygoid narrow posterior to transverse flanges, with quadrate rami almost parallel; interpterygoid vacuities small; dorsal process of premaxilla elongated; maxilla reaches maximum height in posterior; some pachyostosis of upper orbital rim; postorbital bar slightly twisted; $ temporal fenestra larger than biarmosuchids, with expanded (& thickened?) posterodorsal margin for origin of jaw adductors visible in dorsal view (H&B); lack moveable quadrate; paroccipital process contacts quadrate. 

Until recently only two genera -- each of one species, are recorded -- Eotitanosuchus and Ivantosaurus. The latter is known from only two jaw fragments, and seem to be very similar to Eotitanosuchus. Tatarinov (1999) has recently described a new species and genus of eotitanosuchian.  

Genus Eotitanosuchus Chudinov 1960
Type species: E. olsoni Chudinov 1960
Diagnosis: Snout long and high; orbit large; interorbital roof narrow; occiput high; step in the alveolar border (?); lacrimal high and long; vomers fusing (= partially fused?).

Eotitanosuchus olsoni Chudinov 1960
Locality: Echovo locality, Ocher Province, Perm Region, eastern European Russia
Age: Upper Kazanian, Middle Permian (Late Roadian/early Wordian)..
Size: skull: 35 cm, overall length may have been over 2 meters

The holotype is a crushed and deformed skull. Additional skull and skeletal material is known. 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.

Ivantosaurus ensifer Chudinov 1983 ? = Eotitanosuchus ensifer (Chudinov)
Locality: Echovo locality, Ocher Province, Perm Region, eastern European Russia
Age Upper Kazanian, (Late Roadian/early Wordian).
Holotype and only known material, maxilla and quadrate found in association and in their respective natural positions.

Either a giant individual of Eotitanosuchus (if E. olsoni is a juvenile this would therefore be a large adult), or, perhaps more likely, a distinct species. This is a very large animal (length would have been around 6 meters). Maxilla short and high. Two upper canines, long, and with their axes inclined forward. It is not clear if one of the canines is a replacement tooth. Sigogneau-Russell (1989) seems to think this is unlikely, which would make this a quite different animal from Eotitanosuchus. As with the therocephalian "family" Lycosuchidae, these may simply be replacement canines. There are few known animals, 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 Roadian/early Wordian)..
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.

Links: Eotitanosuchus; Stars of the Show (A to I); therapsid3a; Paleontology and Geology Glossary: E. 

References: Battail & Surkov (2000); Hopson & Barghusen (1986); Ivakhnenko (1999); Sigogneau-Russell (1989); Tatarinov (1999).  

Image: Three specimens of Biarmosuchus tener (a-c) compared to Eotitanosuchus olsoni (d) as reconstructed by Ivakhnenko (1999). ATW020727; MAK000808.