With the decline of the Kungurian and Ufimian Caseids, the herbivorous Estemmenosuchids took over the role of as top herbivore. These were massive, clumsy-looking animals, with a sprawling posture, and reaching the size of an adult bull, although some types were smaller.
The skull is high and massive. The creature is equipped with several bizarre set of large horns projecting both upwards and outwards, probably used for intra-specific display. There are five large teeth in the maxillae (upper jaw bone), rather short canines, and at least twenty small and uniform post-canines. Each tooth has a swollen crown and a sharp, laterally compressed serrated apex. There are also numerous small teeth on the palate (vomers, palatines and pterygoids). The reduced side teeth , with a bulky body for digesting volumes of plant food indicate a herbivores lifestyle, despite the large canines. Vegetable matter was grasped with the strong front teeth and swallowed without chewing, as the weak and thin side teeth only served to keep food in the mouth. These animals would nevertheless have taken carrion when they could find it, as the great force exerted by the chisel-like front teeth could cut up meat quite easily.
As with the Tapinocephalids of the early Capitanian epoch, a number of types are known, and it seems like for a short time they constituted a successful evolutionary radiation. Connections are sometimes suggested with the Styracocephalidae, but in the Estemmenosuchids the 'horns' situated on the frontals, and directed dorsally, whereas in the Styracocephalidae the 'horns' are formed by the tabular and directed posteriorly. Otherwise their features very similar to those of the Styracocephalidae. It is not possible to say tehrefore whether the relationship is one of ancestor-descendent or simply evolutionary convergence due to similiar lifestyle (although the different bones forming the horns would suggest to me the latter).
The remains of Estemmenosuchus have been found in a channel flood deposit, indicating that they probably frequently lowland and marshy areas.
Estemmenosuchids were probably at least partially endothermic (warm-blooded), although body temperature was also maintained by their large size
Ecological niche: large to very semi-aquatic to terrestrial herbivores
Modern equivalent: hippo???
Time: middle Permian
Distribution: although so far fossil remains are known only from eastern Russia it is likely these animals had a much wider, probably worldwide ( Pangea) distribution
preferred food: plants
length: from 1.5 to 4.5 meters
weight: 50 kg to 1500 kg
Metabolism: partially endothermic? gigantotherms (Homeotherms)
Predators: Eotitanosuchids, Brithopodids
Ancestor: basal dinocephalian or proto-Phthinosuchus-like ancestor?)
Replaced: Large Caseids
Replaced by: Titanosuchids and Tapinocephalids
Taxonomic status - Family
Family Estemmenosuchidae Tchudinov 1960
Estemmenosuchus uralensis Tchudinov, 1960
Estemmenosuchus mirabilis Tchudinov, 1968
Molybdopygus arcanus Tchudinov 1964
Known from an exceptionally thick-walled and massive pelvic girdle, this specimen was originally considered brithopodid. This genus is distinguished from Estemmenosuchus by the thicker walled, more massive pelvis, the presence of flat facets at the posterior end of the acetabulum and a high pubo-ischiadic symphysis. No skull is known
Anoplosuchia tenuirostris Tchudinov 1968b
A medium sized estemmenosuchid with a comparatively narrow skull. Preorbital region long, rather low and broad; postorbital short, weak, broad and high. Preorbital region without excrescences or thickening except in thc posterior nasal region. Outer edge of jaw in region of canine bears weak boss. Incisors more or less equal in size to canines.
Zopherosuchus luceus Tchudinov 1983
A relatively small estemmenosuchid about 1.5 meters long. Frontal and parietal bones of the skull panicularly thickened.
|some Links and References|
Estemmenosuchus uralensis - same content as preceeding page, but bigger photo
Gillian M. King, "Anomodontia" Part 17 C, Encyclopedia of Paleoherpetology, Gutsav Fischer Verlag, Stuttgart and New York, 1988
Peter K. Chudinov, "New Facts about the Fauna of the Upper Permian of the USSR", Journal of Geology, 1965, 73:117-30
Dinocephalia after Carroll 1988 - cladogram and genus list, based on Carroll (see next reference) - Mikko K. Haaramo
Robert L. Carroll Vertebrate Paleontology and Evolution - W. H. Freeman and company, New York, 1988
Stars of the Show - includes Estemmenosuchus
Palaeos Page (incorporates some of this material, plus a lot of additional material)