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 ... square-mile (2.6-million ...

However, even the trilobites' evolution could not help the trilobites escape the Permian Period, where there was a mass ...

This graph plots extinction rates of marine animal families over ... but the fossil record is unclear. The two biggest extinctions were at the end of the Permian Period, about 250 million years ...

The Triassic Period was a time of great change. Bookended by extinctions, this era saw huge shifts in the diversity and dominance of life on Earth, ushering in the appearance of many well-known groups ...

The remarkable discovery includes hundreds of well-preserved footprints of reptiles, amphibians, and insects from the Permian period ... in size: up to 2-3 meters in length," Dal Sasso said ...