title: Asa Issie, Aramis and the origin of Australopithecus.
abstract: The origin of Australopithecus, the genus widely interpreted as ancestral to Homo, is a central problem in human evolutionary studies. Australopithecus species differ markedly from extant African apes and candidate ancestral hominids such as Ardipithecus, Orrorin and Sahelanthropus. The earliest described Australopithecus species is Au. anamensis, the probable chronospecies ancestor of Au. afarensis. Here we describe newly discovered fossils from the Middle Awash study area that extend the known Au. anamensis range into northeastern Ethiopia. The new fossils are from chronometrically controlled stratigraphic sequences and date to about 4.1-4.2 million years ago. They include diagnostic craniodental remains, the largest hominid canine yet recovered, and the earliest Australopithecus femur. These new fossils are sampled from a woodland context. Temporal and anatomical intermediacy between Ar. ramidus and Au. afarensis suggest a relatively rapid shift from Ardipithecus to Australopithecus in this region of Africa, involving either replacement or accelerated phyletic evolution.
authors.affiliation: Human Evolution Research Center, Museum of Vertebrate Zoology, 3101 Valley Life Sciences Building, University of California at Berkeley, Berkeley, California 94720, USA. timwhite@berkeley.edu
authors.forename: Tim D
authors.initials: TD
authors.lastname: White
authors.forename: Giday
authors.initials: G
authors.lastname: WoldeGabriel
authors.forename: Berhane
authors.initials: B
authors.lastname: Asfaw
authors.forename: Stan
authors.initials: S
authors.lastname: Ambrose
authors.forename: Yonas
authors.initials: Y
authors.lastname: Beyene
authors.forename: Raymond L
authors.initials: RL
authors.lastname: Bernor
authors.forename: Jean-Renaud
authors.initials: JR
authors.lastname: Boisserie
authors.forename: Brian
authors.initials: B
authors.lastname: Currie
authors.forename: Henry
authors.initials: H
authors.lastname: Gilbert
authors.forename: Yohannes
authors.initials: Y
authors.lastname: Haile-Selassie
authors.forename: William K
authors.initials: WK
authors.lastname: Hart
authors.forename: Leslea J
authors.initials: LJ
authors.lastname: Hlusko
authors.forename: F Clark
authors.initials: FC
authors.lastname: Howell
authors.forename: Reiko T
authors.initials: RT
authors.lastname: Kono
authors.forename: Thomas
authors.initials: T
authors.lastname: Lehmann
authors.forename: Antoine
authors.initials: A
authors.lastname: Louchart
authors.forename: C Owen
authors.initials: CO
authors.lastname: Lovejoy
authors.forename: Paul R
authors.initials: PR
authors.lastname: Renne
authors.forename: Haruo
authors.initials: H
authors.lastname: Saegusa
authors.forename: Elisabeth S
authors.initials: ES
authors.lastname: Vrba
authors.forename: Hank
authors.initials: H
authors.lastname: Wesselman
authors.forename: Gen
authors.initials: G
authors.lastname: Suwa
mesh_terms: D000818:Animals; D005075:Biological Evolution; D003817:Dentition; D004777:Environment; D005002:Ethiopia; D005269:Femur / Q000033:anatomy & histology; D005580:Fossils; D005843:Geography; D049690:History, Ancient; D015186:Hominidae / Q000033:anatomy & histology / Q000145:classification* / Q000502:physiology*; D010163:Paleontology; D010802:Phylogeny; D013997:Time Factors