About 250 million years ago, at the end of the Permian period, something killed some 90 percent of the planet's species. Less than 5 percent of the animal species in the seas survived. On land ...

While such early synapsids would have been capable of bursts of speed, they weren’t especially quick and lacked the endurance ...

Fine-tuning the evolution of therapsids during the early part of the Permian Period (299 million to 252 million years ago) is particularly important for tracing the ancestry of mammals ...