Inostrancevia was a large, carnivorous therapsid, part of the gorgonopsid group, that lived during the Late Permian period, around 260 to 251 million years ago. It was among the apex predators of its time, measuring up to 4 meters (13 feet) in length. Inostrancevia had a long, robust skull with saber-like canine teeth, which it used to prey on large herbivores like Scutosaurus. Its body was muscular and built for agility, making it a formidable hunter in the terrestrial ecosystems of prehistoric Russia, where its fossils were discovered. Inostrancevia represents an important step in the evolution of mammal-like reptiles before the Permian mass extinction.