<P> Crinoids ("sea lilies") suffered a selective extinction, resulting in a decrease in the variety of their forms . Their ensuing adaptive radiation was brisk, and resulted in forms possessing flexible arms becoming widespread; motility, predominantly a response to predation pressure, also became far more prevalent . </P> <P> Lystrosaurus, a pig - sized herbivorous dicynodont therapsid, constituted as much as 90% of some earliest Triassic land vertebrate fauna . Smaller carnivorous cynodont therapsids also survived, including the ancestors of mammals . In the Karoo region of southern Africa, the therocephalians Tetracynodon, Moschorhinus and Ictidosuchoides survived, but do not appear to have been abundant in the Triassic . </P> <P> Archosaurs (which included the ancestors of dinosaurs and crocodilians) were initially rarer than therapsids, but they began to displace therapsids in the mid-Triassic . In the mid to late Triassic, the dinosaurs evolved from one group of archosaurs, and went on to dominate terrestrial ecosystems during the Jurassic and Cretaceous . This "Triassic Takeover" may have contributed to the evolution of mammals by forcing the surviving therapsids and their mammaliform successors to live as small, mainly nocturnal insectivores; nocturnal life probably forced at least the mammaliforms to develop fur and higher metabolic rates, while losing part of the differential color - sensitive retinal receptors reptilians and birds preserved . </P> <P> Some temnospondyl amphibians made a relatively quick recovery, in spite of nearly becoming extinct . Mastodonsaurus and trematosaurians were the main aquatic and semiaquatic predators during most of the Triassic, some preying on tetrapods and others on fish . </P>

What animals went extinct in the permian extinction