Changing biologic selectivity of extinction in the Foraminifera over the past 150 m.y.

Extinctions of foraminifera 91 m.y. ago show the greatest number of patterns of selective morphologic and geographic extinction documented in the fossil record. Those taxa at significantly greater risk of extinction include those with agglutinated tests, discoidal shape, tropical ranges, and narrow latitudinal ranges. These results cast doubt on anoxia as the causal mechanism for foraminiferal extinction in the late Cenomanian. Significantly selective extinction of foraminifera with calcareous tests in the upper Eocene and lack of selective extinction at the Cretaceous-Tertiary (K-T) boundary demonstrate that mass extinctions can exhibit numerous patterns of biologic selectivity.