This graph plots extinction rates of marine animal families over the last ... These occurred at the end of the Ordivician, the Late Devonian, the Permian/Triassic (P/Tr) boundary, the end of ...

Prototaxites in an Early Devonian landscape, approximately 400 million years ago. Painting by Mary Parrish, National Museum of Natural History, via the University of New Hampshire. Since their ...