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Lecture

Australopithecines

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Department
Anthropology
Course
ANT 301
Professor
Chris Kirk
Semester
Spring

Description
Australopithecines*** Monday, April 08, 2013 2:10 PM Au. Aafricanus is an austrialopithecine: • Superfamily Hominiodea: apes + humans o Family Hylobatidae: gibbons (Hylobates) o Family Pongidae: orangutans (Pongo) o Family Hominidae: African hominoids • Subfamily Gorillinae: Gorilla • ***** Australopithecines • Earliest/most primitive hominins; all from Africa • LIKE Homo and unlike Pan o Bipedal o Most have thick enamel o Varying degrees of canine reduction • UNLIKE Homo o Small brain (Like Pan) o Most have larger cheek teeth than any living hominoid. Toros-Menalla, Chad: 7-6 MYA: Ancient Lake Margin • Sahelanthropus tchadensis o Michel Burnet 2002 o Massive, thick supraorbital torus (like gorilla) o Very small endocrinal volume: 320 cc (Pan = 400 cc) o Small Molars o Not like most australopithecines o Why possible hominin? • Intermediate enamel thickness (< Homo; > apes) • Intermediate canine size w/apical wear o Digital Reconstruction from CT Scan found: • Less prognathic (jaw didn't stick out) • Supraorbital torus morphology differs from apes • Forward placement of foramen magnum (bipedal bone on neck) Tugen Hills, Kenya: 6 MYA: East African Rift Valley: River and Lake Deposits • Orrin tugenensis o Brigitte Senut & Martin Pickford, 2001 o Small molars with thick enamel o Large pointed canines o Distal humerus and long curved manual phalanx: climbing adaptations o Why hominin (besides thick enamel)? • Cortical bone in femoral neck asymmetrical (associated with bipedalism) Aramis, Ethiopia: 5.8-4.4 MYA: Afar Triangle: Middle Awash • Ardipithecus ramidus o Named in 1994 o Long powerful arm and small molars with think enamel (chimp-like) o BUT foramen magnum shifted forward … o Later ta same year, crushed skeleton found o Team spent next 15 years preparing and studying the skeleton… o "Ardi" : Adult female skeleton described 2009 o The bad news: • Cranium is busted up.. o The good news: • Most of it's there! • Digital reconstruction based on computerized tomography o Morphologically very primitive cranium. Small ECV (about 300 cc, similar to female chimp) o Arboreal climbing adaptations • Hand with long curved phalanges and short thumb • Foot with abducted hallux and long toes o BIPEDAL when on the ground • BUT_ pelvis reveals short, broad, laterally facing ilium o Final note: White et al. claim that Orrorin and Sahelanthropus are actually just Ardipithecus Kanapoi and Allia Bay, Kenya 4.2-3.9 MYA • 1995 Alan Walker and Meave Leakey named a new species: Australopithecus anamensis • Jaw Chimp-Like: o Prognathic o Long and Narrow • HOWEVER
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