PHYLOGENY AND RATES OF CHARACTER EVOLUTION AMONG RINGTAIL POSSUMS (PSEUDOCHEIRIDAE, MARSUPIALIA)

A total of 47 craniodental characters seen in fossil and extant ringta il possums (Pseudocheiridae: Marsupialia) were examined using Wagner, Camin-Sokal, and Dollo parsimony. All extant species form a clade to t he exclusion of Miocene genera. Hemibelideus and Petauroides are siste r taxa, as are Petropseudes and Pseudochirops. All species of Pseudoch eirus are united together, except Pseudocheirus peregrinus, the phylog enetic position of which is uncertain on the basis of craniodental inf ormation. Overall, the agreement between cladistic analyses of craniod ental characters and biochemical analysis is excellent, although the l atter provide much stronger evidence that P. peregrinus is a sister ta xon to other Pseudocheirus species. Rates of evolution of craniodental characters are highest in the Pseudochirops-Petropseudes lineage, whe re widening of the molars, elaboration of cusps and conules, accentuat ion of cristae and cristids, and the development of highly crenulated enamel create a dental battery that is better equipped to process plan t material. Pseudocheirus displays the least modification of the presu med primitive dental condition.