Mammal
The Permian-Triassic extinction event, which was a prolonged event due to the accumulation of several extinction pulses, ended the dominance of the carnivores among the therapsids. In the early Triassic, all the medium to large land carnivore niches were taken over by archosaurs which, over an extended period of time (35 million years), came to include the crocodylomorphs, the pterosaurs, and the dinosaurs. By the Jurassic, the dinosaurs had come to dominate the large terrestrial herbivore niches as well.
During which time period did archosaurs begin to take over as the dominant carnivore?
Triassic
In the early Triassic, all the medium to large land carnivore niches were taken over by archosaurs which, over an extended period of time (35 million years), came to include the crocodylomorphs, the pterosaurs, and the dinosaurs.
archosaurs