Abstract

Rates of origination and extinction for marine invertebrates fell at the onset of the late Paleozoic ice age in late Mississippian time and remained low until glaciation ended in middle Permian time. Through the use of a database of stratigraphic and geographic occurrences of brachiopod genera, these macroevolutionary changes are traced to the loss of genera with narrow latitudinal ranges, which had intrinsically high turnover rates, at the onset of glaciation in late Viséan time. When glaciation waned in late Sakmarian time, narrowly distributed genera rebounded abruptly and restored the global fauna to its pre– ice-age configuration. Because narrowly distributed brachiopod genera had dominated tropical diversity, the major biotic effects of the late Paleozoic ice age were felt at low latitudes. The climatic regime of this ice age thus altered the marine ecosystem to one characterized by broadly adapted, long-lived genera.

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