Anteosaurus magnificus

Anteosaurus
 is an extinct genus of large carnivorous synapsids. It lived during the
 Capitanian epoch of the Guadalupian in what is now South Africa. Like
the well-known Moschops, they were dinocephalians, a clade of
large-bodied therapsids that flourished from 270 to 260 million years
ago and then went extinct without descendants.

Paleontologists surmise that *Anteosaurus* hunted rather like
crocodiles, pulling land animals into the water. In particular,
scientists point to the animal’s strong tail and weak, sprawling legs.
Its body was well-suited to projecting itself forward, both in hunting
and evidently in head-butting.

*Anteosaurus* had a tall, narrow skull, which is 80 centimetres (31 in) long. It was perhaps the largest known carnivorous non-mammalian synapsid, estimated at 5–6 m (16–20 ft) in length and 500 to 600 kg (1,100 to 1,300 lb) in weight.

The teeth are another identifying characteristic of *Anteosaurus*.
 The teeth on the roof of the mouth are enlarged and confined in a
cluster near the outer tooth row. The "normal teeth" include the anterior, canine and cheek teeth.
 A prominent feature of the dinocephalians is the ledge on the anterior
 teeth. The canine teeth are big, and there are usually about ten cheek
 teeth present. The front of the mouth curves up due to the premaxillary bone of the upper jaw.

As defined by Lieuwe Dirk Boonstra, *Anteosaurus*
 is “a genus of anteosaurids in which the postfrontal forms a boss of
variable size overhanging the dorso-posterior border of the orbit.” On
this basis he synonymised six of the seven genera named from the Tapinocephalus zone: *Eccasaurus*, *Anteosaurus*, *Titanognathus*, *Dinosuchus*, *Micranteosaurus*, and *Pseudanteosaurus*. Of these, he says, *Dinosuchus* and *Titanognathus* can safely be considered synonyms of *Anteosaurus*. *Eccasaurus*,
 with a holotype of which the cranial material consists of only few
typical anteosaurid incisors, appears to be only determinable as to
family. The skull fragment forming the holotype of *Pseudanteosaurus* can best be considered as an immature specimen of *Anteosaurus*. *Micranteosaurus*,
 the holotype of which contains a small snout, was previously considered
 a new genus on account of its small size but is better be interpreted
as a young specimen of *Anteosaurus*. And likewise, the large number of species attributed to the genus *Anteosaurus* can also be considered synonyms. Boonstra still considers as valid the genus *Paranteosaurus*,
 which is defined as a genus of anteosaurids in which the postfrontal is
 not developed to form a boss. This is probably an example of individual
 variation and hence another synonym of *Anteosaurus.*

*Anteosaurus* was once known by a large number of species, but the
current thinking on this is that they merely represent different growth
stages of the same type species, *A. magnificus*.

We have 32 skulls of *Anteosaurus*, of which 16 are reasonably well
 preserved and on them ten species have been named. To differentiate
between the species the following main characters have. been used: the
number, size and shape of the teeth, skull size, shape and the nature of
 the pachyostosis.
 On re-examination it has become clear that the crowns of the teeth are
seldom well preserved; basing the count for the dental formula on the
preserved roots is unreliable. as this is affected by age and tooth
generation; size of skull is a function of age and also possibly sex;
sk~-shape is greatly affected by post-mortem deformation, and the
variability in the pachyostosis, which may be specific in some respects,
 can just as well be the result of...physiological processes. Specific
diagnosis consisting of the enumeration of differences of degree in
features such as the above can hardly be considered as sufficient
indication of the existence of discrete species....*A. magnificus* thus has the following synonyms: *abeli*, *acutirostrus*, *crassifrons*, *cruentus*, *laticeps*, *levops*, *lotzi*, *major*, *minor*, *minusculus*, *parvus*, *priscus* and *vorsteri*.

## Paleobiology

During
 the Permian, two clades of amniotes came to dominate terrestrial
niches: the sauropsids and the synapsids. The synapsids included top
predators, such as Dimetrodon and Gorgonopsia. Anteosaurus were
therapsids, a clade within Synapsida that includes the Permian ancestors
 of mammals.

### Ecology

Reconstruction of *Anteosaurus* showing the animal in crocodile-like posture

Olson notes that the Russian dinocephalian assemblages indicate environments tied to water, and Boonstra considered that the roughly contemporary *Anteosaurus*
 were slinking crocodile-like semi-aquatic forms. The long tail, weak
limbs, and sprawling posture do indeed suggest some sort of
crocodile-like existence.

However the thickened skull-roof indicates that these animals
were quite able to get about on land, if they were to practice the
typically dinocephalian head-butting behaviour. All other head-butters (pachycephalosaurians, titanotheres, and goats)
 were or are completely terrestrial. Perhaps these animals spent some
time in the water but were active on land during the mating season, and
probably quite able to get about on land to hunt for prey.

### Head-butting behavior

*Anteosaurus* like other related therapsids had a thickened skull (pachyostosis), and this has been suggested as an adaptation for head butting, or perhaps more aptly for head pushing. Also like with *Moschops*,
 the overall build seems to have been for projecting its body weight
forwards. Not only could this have been useful in dominance head pushing
 contests, but it may have also been a technique to knock over
unsuspecting or weakened prey.

Reconstruction of *Anteosaurus* showing the animal in crocodile-like posture.