title: Oldest known euarchontan tarsals and affinities of Paleocene Purgatorius to Primates.
abstract: Earliest Paleocene Purgatorius often is regarded as the geologically oldest primate, but it has been known only from fossilized dentitions since it was first described half a century ago. The dentition of Purgatorius is more primitive than those of all known living and fossil primates, leading some researchers to suggest that it lies near the ancestry of all other primates; however, others have questioned its affinities to primates or even to placental mammals. Here we report the first (to our knowledge) nondental remains (tarsal bones) attributed to Purgatorius from the same earliest Paleocene deposits that have yielded numerous fossil dentitions of this poorly known mammal. Three independent phylogenetic analyses that incorporate new data from these fossils support primate affinities of Purgatorius among euarchontan mammals (primates, treeshrews, and colugos). Astragali and calcanei attributed to Purgatorius indicate a mobile ankle typical of arboreal euarchontan mammals generally and of Paleocene and Eocene plesiadapiforms specifically and provide the earliest fossil evidence of arboreality in primates and other euarchontan mammals. Postcranial specializations for arboreality in the earliest primates likely played a key role in the evolutionary success of this mammalian radiation in the Paleocene.
authors.affiliation: Department of Anthropology and Archaeology, Brooklyn College, City University of New York, Brooklyn, NY 11210; New York Consortium in Evolutionary Primatology, New York, NY 10024; Department of Anthropology, Yale University, New Haven, CT 06520; stephenchester@brooklyn.cuny.edu.
authors.forename: Stephen G B
authors.initials: SG
authors.lastname: Chester
authors.affiliation: Florida Museum of Natural History, University of Florida, Gainesville, FL 32611;
authors.forename: Jonathan I
authors.initials: JI
authors.lastname: Bloch
authors.affiliation: Department of Evolutionary Anthropology, Duke University, Durham, NC 27708; and.
authors.forename: Doug M
authors.initials: DM
authors.lastname: Boyer
authors.affiliation: University of California Museum of Paleontology, Berkeley, CA 94720.
authors.forename: William A
authors.initials: WA
authors.lastname: Clemens
mesh_terms: D000818:Animals; D005580:Fossils; D010802:Phylogeny; D011323:Primates / Q000033:anatomy & histology*; D013639:Tarsal Bones / Q000033:anatomy & histology*
keywords: Euarchonta; Paleocene; Primates; evolution; paleontology