Phylogeny and Rates of Character Evolution Among Ringtail Possums (Pseudocheiridae, Marsupialia)

Abstract

A total of 47 craniodental characters seen in fossil and extant ringtail possums (Pseudocheiridae: Marsupialia) were examined using Wagner, Camin-Sokal, and Dollo parsimony. All extant species form a clade to the exclusion of Miocene genera. Hemibelideus and Petauroides are sister taxa, as are Petropseudes and Pseudochirops. All species of Pseudocheirus are united together, except Pseudocheirus peregrinus, the phylogenetic position of which is uncertain on the basis of craniodental information. Overall, the agreement between cladistic analyses of craniodental characters and biochemical analysis is excellent, although the latter provide much stronger evidence that P. peregrinus is a sister taxon to other Pseudocheirus species. Rates of evolution of craniodental characters are highest in the Pseudochirops-Petropseudes lineage, where widening of the molars, elaboration of cusps and conules, accentuation of cristae and cristids, and the development of highly crenulated enamel create a dental battery that is better equipped to process plant material. Pseudocheirus displays the least modification of the presumed primitive dental condition.