title: The oldest known primate skeleton and early haplorhine evolution.
abstract: Reconstructing the earliest phases of primate evolution has been impeded by gaps in the fossil record, so that disagreements persist regarding the palaeobiology and phylogenetic relationships of the earliest primates. Here we report the discovery of a nearly complete and partly articulated skeleton of a primitive haplorhine primate from the early Eocene of China, about 55 million years ago, the oldest fossil primate of this quality ever recovered. Coupled with detailed morphological examination using propagation phase contrast X-ray synchrotron microtomography, our phylogenetic analysis based on total available evidence indicates that this fossil is the most basal known member of the tarsiiform clade. In addition to providing further support for an early dichotomy between the strepsirrhine and haplorhine clades, this new primate further constrains the age of divergence between tarsiiforms and anthropoids. It also strengthens the hypothesis that the earliest primates were probably diurnal, arboreal and primarily insectivorous mammals the size of modern pygmy mouse lemurs.
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origin, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 142 Xi Zhi Men Wai Street, Beijing 100044, China. nixijun@ivpp.ac.cn
authors.forename: Xijun
authors.initials: X
authors.lastname: Ni
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Gebo
authors.forename: Marian
authors.initials: M
authors.lastname: Dagosto
authors.forename: Jin
authors.initials: J
authors.lastname: Meng
authors.forename: Paul
authors.initials: P
authors.lastname: Tafforeau
authors.forename: John J
authors.initials: JJ
authors.lastname: Flynn
authors.forename: K Christopher
authors.initials: KC
authors.lastname: Beard
mesh_terms: D000818:Animals; D005075:Biological Evolution; D016565:Cheirogaleidae / Q000033:anatomy & histology; D002681:China; D003817:Dentition; D005529:Foot Bones / Q000033:anatomy & histology; D005552:Forelimb / Q000033:anatomy & histology; D005580:Fossils; D006614:Hindlimb / Q000033:anatomy & histology; D010802:Phylogeny; D011323:Primates / Q000033:anatomy & histology* / Q000145:classification; D012863:Skeleton; D012886:Skull / Q000033:anatomy & histology; D013623:Tail / Q000033:anatomy & histology