Inostrancevia alexandri Therapsida: Theriodontia: Inostranceviidae Locality: Sokolki, Malaya Severnaya Dvina River, Arkhangelsk Region, northern European Russia Age: Late Permian, 250 million years ago Meaning of name: Named in honor of A. Inostrantzev, Russian geologist Size: The size of large tiger The most dangerous land predators of that time were huge gorgonopsid theriodonts. The largest of these was Inostrancevia. They not only ran quickly but also swam well. Their huge saber-fangs of about 12 centimeters in length permitted them to assault thick-skinned pareiasaurs and dicynodonts. Lateral teeth were small and weak in the upper jaw with none at all in the lower one. Prey was broken up with the help of strong incisors and inasmuch as chewing was impossible whole pieces were swallowed. Represented here by a skeleton of a large sabre-toothed theriodont reptile.
The gracile nature of the skeleton of this animal and its development of many kinds of teeth
marks it as an advanced carnivorous mammal-like reptile, a therapsid.
By this stage of evolution of mammal-like reptiles, the limbs are tucked
more nearly under the body as in living mammals.
This is in contrast to more primitive reptiles that have the upper part of the
limbs projecting outward, rather than downward, thus in sprawling stance, like the
Titanophoneus potens from Isheevo.
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