Suppressed speciation rates and compositional changes in Paleozoic faunas.

Shifts in the taxonomic composition of Paleozoic communities are commomly ascribed to selective extinctions. Suppression realized speciation rates owing shrinkage available adaptive space (lowering potential niche number), even though unselective, results differential diversity losses, greatest losses being sustained by clades with highest and extinction (the high-turnover caldes). The resulting compositional shifts apear be selective. Foreclosures opportunities probably play an important perhaps sorne cases a dominant role during Paleozoic.