Long-period astronomical forcing of mammal turnover.

Mammals are among the fastest-radiating groups, being characterized by a mean species lifespan of the order of 2.5 million years (Myr). The basis for this characteristic timescale of origination, extinction and turnover is not well understood.

Age structure, residents, and transients of Miocene rodent communities.

The age structures of two successive rodent communities are studied on the basis of a rich record from well-dated Miocene sections (17-10 Ma) in north-central Spain. Community age is defined as the mean of the residence times of the community members at the time of the locality age. Community ages are negatively correlated with the numbers of community members.