Updates; May 2009; Scientific American Magazine; by Philip Yam; 1 Page(s)

Permian Puzzle The mass extinction at the end of the Permian period 250 million years ago wiped out at least 90 percent of all ocean species and 70 percent of land vertebrates [see The Mother of Mass Extinctions; SciAm, July 1996]. New findings suggest the deadly event on land might have occurred separately from the one in the oceans.

Paleontologist Robert Gastaldo of Colby College and his colleagues investigated ancient sedimentary rock at South Africas Karoo Basin. Previous expeditions there had identified a distinct boundary between the Permian and the Triassic, which came right after. Dubbed the lifeless zone, this sediment lies over fossils of extinct reptiles and has been the primary evidence of the end-Permian extinctions rapid effects on land.