Last time...
• What is the adaptive niche of the Hominids? • What is the difference between calling this lineage hominid vs. hominin? • What are the defining characteristics of the hominids? • When did hominids first emerge? • Why bipedalism and small canines?
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Tuesday, April 19, 2011 Bipedalism
• What are the advantages and disadvantages of bipedalism? • How does bipedalism change the skeleton? • What are the various theories for the origin and adoption of bipedalism? • Which is the most likely given what we now know about the origins of hominids?
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Tuesday, April 19, 2011 Who did the hominids come from?
Tuesday, April 19, 2011 The Rift Valley
Tuesday, April 19, 2011 The First Hominids?
• Sahelanthropus tchadensis (7.0-6.0 MYA) • Orrorin tugenensis (6.0 MYA) • Ardipithecus ramidus (4.4 MYA) and Ardipithecus kadabba (5.8-5.2 MYA)
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Tuesday, April 19, 2011 Sahelanthropus tchadensis
• 5.2-7 mya • small canines • thick enamel • indications of bipedality
Tuesday, April 19, 2011 Orrorin tugenensis
Orrorin and Pan
Tuesday, April 19, 2011 Orrorin tugenensis
• Kenya • 6 mya • Humerus and femur suggest bipedalism • Thick enamel • Small teeth • Large upper canines
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Tuesday, April 19, 2011 Ardi
Tuesday, April 19, 2011 Ardipithecus ramidus and Ardipithecus kadabba
• A. ramidus 4.4 my A. kadabba 5.7-5.8 my • A. ramidus has smaller canine than A. kadabba • Anterior foramen magnum • Non-weight bearing arm • Grasping feet
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Tuesday, April 19, 2011 Ardipithecus ramidus
Tuesday, April 19, 2011 More Ardipithecus
Tuesday, April 19, 2011 Ardi
Tuesday, April 19, 2011 Ardi bones
Tuesday, April 19, 2011 More Ardi
Tuesday, April 19, 2011 Tuesday, April 19, 2011 Ardipithecus reconstruction
Tuesday, April 19, 2011 Tree
Tuesday, April 19, 2011 Pliocene Hominids Early Australopithecus anamensis (4.2-3.9 mya) Australopithecus afarensis (2.9-2.9 mya) Kenyanthropus platyops (3.5 mya) Australopithecus bahrelghazali (3.5-3.0 mya)
Gracile Robust Australopithecus gahri Australopithecus (P.) aethiopicus (2.5 mya) (2.7-2.5 mya) Australopithecus africanus Australopithecus (P.) boisei (3.5-<2.0 mya) (2.3-1.2 mya) Australopithecus sediba Australopithecus (P.) robustus ~2.0 mya (2.0-1.5 mya) 19
Tuesday, April 19, 2011 Early Australopithecines
Short snout • Bipedal • Relatively Small • • small brain canines and ~420 cc incisors large degree Non- • • of sexual sectorial dimorphism premolar chimp-like large face • • diet
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Tuesday, April 19, 2011 Australopithecus anamensis
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Tuesday, April 19, 2011 Australopithecus anamensis
• 4.2-3.9 mya • Thickened tibia • Primitive dentition • Maybe same as A. afarensis? • Forested environment
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Tuesday, April 19, 2011 A. afarensis
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Tuesday, April 19, 2011 A. afarensis
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Tuesday, April 19, 2011 Laetoli Footprints
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Tuesday, April 19, 2011 Australopithecus afarensis • 3.9-2.9 mya • Short, broad pelvis • tilted femurs • In-line big toe • Sagittal crest • Sexually dimorphic • Small bodied • Small brain
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Tuesday, April 19, 2011 Australopithecus bahrelghazali
• 3.5-3.0 mya • Western africa - Chad • Same as A. afarensis?
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Tuesday, April 19, 2011 Kenyanthropus platyops
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Tuesday, April 19, 2011 Kenyanthropus lateral
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Tuesday, April 19, 2011 A. afarensis and K. platyops
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Tuesday, April 19, 2011 Kenyanthropus platyops
• 3.5 mya • Flat face • Small molars • Australopithecus? Even A. afarensis?
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Tuesday, April 19, 2011 Evolutionary Relationships
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Tuesday, April 19, 2011