crazy-zoologist.livejournal.com/564589.html Bear with a monstrous bite.
The huge fossil bear Agriotherium africanum (or, according to another view of the taxonomy of Agriotherium sivalense africanum), which lived in Africa about 5 million years ago, according to some scientists, had the strongest bite of all land carnivorous mammals.
Dr. Stephen Wroe of the University of Newcastle (Australia) and his team using computer topography have created 3D models of the skulls of various members of the bear family (Ursidae): a brown bear (Ursus arctos), two skulls of a polar bear (Ursus maritimus), a Himalayan bear (Ursus thibetanus), giant panda (Ailuropoda melanoleuca) and African agriotherium (Agriotherium sivalense / africanum). Thanks to 3D models created by student Chris Oldfield, scientists were able to determine how well the skulls of these bears could withstand loads that simulate killing and resistance.
This analysis revealed that the jaw strength of the African agriotherium was incredible and exceeded that of all living large cats and bears. Curiously, among modern bears, the jaws of the giant panda, the most herbivorous of the bears, have the highest resistance to stress, and the jaws of the polar bear, the most carnivorous member of the family, have the lowest. This is due to the fact that the giant panda eats a very tough food - bamboo and is in fact a specialized sclerophage, while the polar bear primarily feeds on seal oil (blubber). In this regard, the polar bear has rather weak jaws for a predator of this size, but it has well-developed large canines (larger than that of all other modern bear's) and incisors, with which it rips the skin of its prey.
Interestingly, in the above analysis, scientists bypassed other fossil bears, including the largest of them - the giant arctotherium, or the giant South American short-faced bear (Arctotherium angustidens), the giant arctode, or the giant North American bear (Arctodus simus) and the large cave bear ( Ursus spelaeus). Therefore, the question of which type of bearish had the strongest jaws at the moment remains open.
There is still no consensus about the lifestyle of the agriotherians and their systematic position. Some are inclined to distinguish African agriotherium as a separate species, while others (for example, G.F. Baryshnikov) distinguish African agriotherium as a subspecies of Agriotherium sivalense.
In some morphological features, the agriotherium shows similarities with giant pandas. These features include the structure of the bony palate, which almost does not go back to the second premolar of the upper jaw, waste of the alisfenoid canal, a round opening and orbital fissure opening with one opening, the presence of a large parastyle on P4, etc. In addition, the genus Agriotherium demonstrates some similarity in dental morphology with the late representatives of the Hemicyon bears (subfamily Hemicyoninae).
As for the way of life, in particular, whether the agriotherium was a superpredator or just a huge scavenger, a kind of "hyperhygiene", then on this topic one can endlessly speculate and speculate. Considering the very large size of the animal and its extremely wide distribution (which can be compared with the Pleistocene range of distribution of lions) and taking into account that it was a representative of the bear family, that is, predatory mammals with an extremely plastic diet, it would be most correct to see an omnivorous predator in the agriothemy , who could kill large prey, did not disdain carrion and, in addition, diversified his diet with plant foods.
However, you should not consider him a bear specialized in a vegetarian diet. Despite some morphological similarity with the giant panda, which was mentioned above, the agriotherium also has other completely different features that do not allow one to see a vegetarian in agriotherium. In bears that prefer plant food, the molars are flat and the canines are shortened. If we compare the skull of the Agriotherium with the same giant panda, then the much larger fangs of the Agriotherium and the more "predatory" profile of the entire skull, which resembles the skull of a large canine, are striking. The chewing surface of the molars of the giant panda is much larger than that of the agriotherium, which, on the contrary, is characterized by premolars with sharper edges, although not as sharp as those of typical carnivores such as felines or canines. The upper predatory tooth (fourth upper premolar) of the agriotherium has a large parastyle, a massive and elongated metacone that forms cutting ridges and a short paracon, which is characterized by sharp anterior and posterior carinae. The internal projection of the tooth is long, massive and bears a large pointed protocon.
Based on all this, we can conclude that the agriotherium led a much more predatory lifestyle than the giant panda and the percentage of meat food in its diet was higher than that of all modern bears, with the exception of most likely the polar bear, whose almost 100% meat diet is determined by the way life and distribution area of ββthis peculiar arctic predator.
What prevents to see in agriotheria the so-called "hyperhygiene", a huge scavenger-terrorist? Let's turn to modern mammals. The spotted hyena (Crocuta crocuta), which is a highly specialized scavenger, nevertheless hunts very successfully and in some regions of Africa even more often than lions. A mammalian predator needs a lot of meat, so it is quite difficult for an animal weighing more than 40 kg to survive on one carcass, even taking into account the abundance of various herbivores. Other hyenas, smaller in size than the spotted hyena, hunt much less frequently and the percentage of falls in their diet is much higher, despite the fact that the craniodental morphology of the spotted hyena is more specialized for carrion than all other modern hyenas.
The agriotherium's dental morphology, in turn, shows much less specialization as a bone-crushing scavenger than the aforementioned spotted hyena. In addition, the agriotherium is much larger than a hyena and requires much more food to maintain its nromal state. Consequently, in order to rely mainly on carrion alone, agriotheria would have to survey much larger territories than hyenas, which did not justify the expenditure of energy at all.
It is also not worth considering agriotherium as a specialized predator, like modern cats, since its dental morphology in this case suggests that he was a less specialized meat eater than representatives of the feline family. In addition, with its enormous size and bearish build, it could not develop as high a speed as modern large felines. However, if we compare it with modern bears, it is clear that, compared to them, the agriotherium was relatively lighter in build and had longer limbs, which allowed it to hunt more successfully than modern brown bears. The latter, despite their omnivorousness, often hunt, including large animals, catching up, despite their barrel-shaped physique and seeming awkwardness, such swift-footed animals as deer (especially on rough terrain). If a brown bear is able to accelerate to such incredible speeds for an animal with a similar physique (according to some estimates, more than 55 km per hour), then it is safe to say that the agriotherium could develop even greater speed than its shorter-legged and clumsy brown relative.
Based on the foregoing, the agriotherium was a large omnivorous predator who preferred meat to any other food and, depending on the circumstances, hunted himself or took prey from others, weaker, by a predator, and on occasion ate plant food.