These are Dinocephalia moving towards a fairly primitive herbivorous condition. The large canine has been retained and the very strong incisors have a piercing talon and a crushing heel. Although the sharp front incisors and fanglike canines at the front of the jaws, might seem to indicate a carnivorous diet, the long series of post-canine teeth have leaf-shaped and serrated spatulate crowns, indicating these animals were at leats partally herbivorous diet. Titanosuchids share with the more specialised Tapinocephalids the presence of an enlarged heel on the incisor teeth, with a reduced canine, with the jaw hinge still further anterior. There is however very little pachyostosis (thickening of the skull), indicating these animals probably did not practice intra-specific head-butting.
There are only two genera, distinguished only by length of limb bones. It is sometimes suggested that the short-limbed Jonkeria was a herbivore, and the longer limbed Titanosuchus a carnivore. Boonstra in his review has the family Titanosuchidae composed of two genera and nine species. I think this many species is excessive, it was probably no more than three or four species. Boonstra also states that the genera Titanosuchus and Jonkeria cannot be distinguished from one another on either cranial or dental characters, but in Titanosuchus the limb-bones are long, whereas in all the species of Jonkeria they are short and squat. However, Gillian King in her review suggetss a number of differences, includiung a large and massive skull in Titanosuchus, and a medium to large skull in Jonkeria, indicating Titanosuchus's supposedly carnivorous lifestylle in contrats to the presumably herbivorous Jonkeria More probably both were omnivores, eating mostly plants, but sometimes carrion or even live animals (comparable omnivores today include bears, pigs, and baboons).
As is so often the case, the understanding of this group has been cluttered by a terrible excess of useless names, described on the basis of fragmentary material, and giving the impression that there were many more species around thebn there really were. The problems began when Sir Richard Owen, the famous English paleontologist, described Titanosuchus ferox in 1879 based on the roots of an incomplete set of teeth. As all the material from the Karoo was new to science at the time that even the poorest specimen warranted description.
In the race to name as many new species as possible Broom added a ballast of names on equally poor material. It has since been shown that even well-preserved batteries of teeth exhibit so much variation, with even the left and right sides of the same skull, so that dental features are a very unreliable criterion for distinguishing between titanosuchids.
Ecological niche: large herbivore/Omnivore
Guild: large herbivore/omnivore/carnivore
Modern equivalent: none
Time: early late Permian ( early Capitanian epoch], lthough they presumably evolved during the Wordian epoch.
Distribution: although so far fossil remains are known only from southern Africa, but it is likely these animals had a much wider, probably worldwide ( Pangea) distribution
preferred food: plants, carrion?
length: upto 4.5 meters
weight: upto 1500 kg
Metabolism: partially endothermic gigantotherms (Homeotherms)
Predators: Anteosaurine Brithopidids
Replaced by: Large Dicynodonts and Pareiasaurs???
Descendents: hypothetical Wordian proto-Titanosuchids gave rise to the Tapinocephalids
Taxonomic status - Family
Two genera - the long-legged Titanosuchus and the short-legged Jonkeria - and a number species seem to be valid. These are briefly described (along with synonyms) here:
genus Titanosuchus Owen 1879
Titanosuchus ferox Owen, 1879
The type material is such that a diagnosis based on the available features of the dentition is that given for the family and can equally be applied to Jonkeria. The associated limb-bones, however, enable us to formulate a generic diagnosis to distinguish this genus from Jonkeria.
Scapanodon septemfontis Boonstra, 1955 - Only postcranial bones are known. As the impeffect humerus cannot be distinguished from that of Scapanodon daplessisi, this is therefore a synonym of the former species and thus of the Titanosuchus.
Parascapanodon avtfontis Boonstra, 1955 - The humerus and femur are so similar to that of Titanosuchus that this form should be included in the genus.
A number of specimens, described by me under the name Parascapanodon, together give a full picture of the dentition, but nothing determined in these specimens is incompatible with the inadequately preserved dentition of the holotype of Titanosuchus ferox. The cranial, dental and postcranial characteristics described under the names Titanosuchus, Scapanodon and Parascapanodon can also be considered as synonymous with Titanosuchus ferox
genus Jonkeria Van Hoepen 1916b
Type species: Jonkerta truculenta Van Hoepen 1916 b
While Titanosuchus seems an animal of rather medium size (by Dinocephalian standards), Jonkeria was of gigantic proportions - around four and a half meters in length. In this large lumbering carnivore the snout of the heavy head was elongated and provided with sharp teeth including large incisors, behind which, on each side above and below were long piercing canines. The cheek teeth were comparatively small. The body was robust and the limbs were very stout.
In Jonkeria some of the species, where good cranial material is known, can be distinguished on differences in cranial structure and the others only on postcranial features. Clearly some of these forms will turn out to be synonymnous, once better material is known Jonkeria truculenta Van Hoepen, 1916 The holotype consists of a good skull and most of the postcranial skeleton. There is another good skull with lower jaw in the South African Museum collection, and other material. A number of specimens indicate the dentition is too variable for use in distinguishing between species. The limb bones are long, in contrast to Titanosuchus
Synonyms - Phoneosuchus angusticeps Broom, 1929 - A good mandible that Boonstra observes has all the characters of the genus Jonkeria and which he includes it in the species truculenta.
Jonkeria ingens (Broom), I 923
The holotype, originally Dinophoneus ingens, together with its synonym, Jonkeria pugnax Broom, 1929, and three other known skulls constitute a distinct species of Jonkeria.
Jonkeria vanderbyli Broom, 1929
The holotype is a good skull of Jonkeria which according to Boonstra is easily distinguishable from the other species of the genus.
Jonkeria haughtoni (Broom, 1929)
The type is a fairly good skull, with some limb-bones, which can be placed in the genus Jonkeria. It can be distinguished from the other species of the genus.
Synonyms: - Dinosphageus haughtoni Broom, 1929 - original name
Jonkeria crassus Broom, 1929 - According to Boonstra, in the holotype consisting of dentaries and postcranial bones, the humerus cannot be distinguished from that of Jonkeria haughtoni, and as there are no other distinctive features it should be considered a synonym of J. haughtoni.
The following species, although distinct, are most likely to turn out eventually to be synonyms of already named types (Given competition for resources among similiar animals, I cannot imagine more than two species of Jonkeria)
Jonkeria koupensis Boonstra, 1955 - The holotype is a good pelvis readily distinguishable from that of any other known species of Jonkeria.
Jonkeria parva Boonstra, 1955- A small humerus is quite distinct from that of the other known species of Jonkeria. I think it is not unlikely this may turn out to a distorted or otherwise modified specimen.
Jonkeria rossouwi Boonstra, 1955 - The holotype consists of postcranial bones readily distinguishable from those of the other species of the genus. Two other specimens are known that show the same distinctive features, indicating this is a valid type (probably corresponding to one of the species name on skull characteristics).
Jonkeria boonstrai Janensch, 1959 - According to Boonstra Janensch has given a convincing diagnosis of the specific features of the holotype skull. He also stresses the herbivorous nature of the dentition.
Titanosuchus cloetei (Broom, 1903) - A piece of jaw bone determinable only to the family.
Scapanodon duplessisi Broom, 1904 - The cranial features are indeterminate. The humerus cannot be distinguished from that of Titanosuchus. The skull is the same as that of Jonkeria.
Archaeosurhus cairncrossi Broom, 1905 - The type specimen is too poor to diagnose. The name is thus nomen dubium
Lamiasaurus newtoni Watson, 1914 - A jaw fragment that may be either titanosuchid or anteosaurid.
Titanosuchus dubius (Haughton, 1915) - The teeth roots allow only identification to the family Titanosuchidae.
Dinartamus vanderbyli Broom, 1923 - The fragments on which this name is based have features too indefinite for a generic diagnosis and can only be considered as titanosuchian.
Enobius strubeni Broom, 1923 - These pieces of jaw can only be identified as titanosuchian.
Dinocynodon dubius (Broom, 1929) - The oval outline of the cross section of the canine is not a sufficiently valid characteristic; and this specimen again can only be identified as titanosuchian incertae sedis.
Scullya gigas Broom, 1929 - This poorly preserved snout shows no definite titanosuchian characters, but the possible presence of teeth on the palatine may be an anteosaurid character. The specimen must be considered indetermitable.
Dinopolus atrox Broom, 1936 - The features exhibited in this snout are those known as characters of the genus Jonkeria and cannot be used for specific diagnosis
|some Links and References|
L. D. Boonstra, "The Fauna of the Tapinocephalus Zone (Beaufort Beds of the Karoo)", Annals of the South African Museum, 56 (1) 1969, pp. 1-73
Carroll, R. L. Vertebrate paleontology and evolution. -W. H. Freeman and company, New York, 1988
Edwin H. Colbert, Evolution of the Vertebrates, 2nd edition, 1969, John Wiley & Sons
James A. Hopson and Herbert R. Barghusen, "An Analysis of Therapsid Relationships", in The Ecology and Biology of Mammal-Like Reptiles ed. by Nocholas Hotton III, Paul D. MacLean, Jan J. Roth and E. Carol Roth, Smithsonian Institute Press, Washington and London, 1986, pp.83-106
Gillian M. King, "Anomodontia" Part 17 C, Encyclopedia of Paleoherpetology, Gutsav Fischer Verlag, Stuttgart and New York, 1988
Illustrated Encyclopaedia of Dinosaurs and Prehistoric Animals, Barry Cox, R.J.G.Savage, Brian Gardiner, Dougal Dixon, illustration by Steve Kirk)
Palaeos Page (incorporates some of this material, plus a lot of additional material)