Major patterns in the history of carnivorous mammals

The history of carnivorous mammals is characterized by a series of rise-and -fall patterns of diversification in which declining clades are replaced by phylogenetically distinct but functionally similar clades. Seven such exam ples from the last 46 million years are described for North America and Eur asia. In three of the seven turnover events, competition with replacement t axa may have driven the decline of formerly dominant taxa. In the remaining four this is less likely because inferred functional similarity was minima l during the interval of temporal overlap between clades. However, competit ion still may have been important in producing the rise-and-fall pattern th rough suppression of evolution within replacement taxa; as long as the larg e carnivore ecospace was filled, the radiation of new taxa into that ecospa ce was limited, only occurring after the extinction of the incumbents. The apparently inevitable decline of incumbent taxa may reflect the tendency fo r clades of large carnivorous mammals to produce more specialized species a s they mature, leading to increased vulnerability to extinction when enviro nments change.