Assertion: extinction | /r/HasProperty | time periods
Facets:
value: unlike the shorter mass extinctions
type: OTHER
Source sentences:
text: Most extinctions occur as background extinctions because they are longer time periods unlike the shorter mass extinctions which there were only two in the Paleozoic era, the Ordovician mass extinction, and the Permian/Triassic extinction in which 95% of all marine animals became extinct