Temporal data in phylogenetic systematics: an example from the mammalian fossil record

A method of phylogenetic inference is proposed for taxa that are known from large samples spaced closely in time. The method employs elements of cladistic and stratophenetic methods, and consists of four steps. 1) Morphologically homogeneous clusters are recognized within temporally and geographically constrained samples. 2) Temporally disjunct and geographically dispersed taxa are recognized, and their anagenetic evolution and geographic variation documented. 3) A character matrix is constructed for the taxa and analyzed cladistically. 4) Resulting cladograms are used to construct a phylogenetic tree with additional input from temporal, morphological, ecological, and geographical data. This method supplements the use of cladistically analyzed morphological data with data that are not suited for cladistic analysis, and thus reduces the amount of unused data.