Ardipithecus ramidus
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Ardipithecus ramidus. Hominid who walked bipedally 4.4 mya Discovered in 1992 by Tim White in Aramis, Ethiopia (as yet largely unpublished) Distinct enough to be a new species? ape-like dentition bipedal locomotion overall hominid-like skeleton

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Ardipithecus ramidus l.jpg
Ardipithecus ramidus

  • Hominid who walked bipedally 4.4 mya

  • Discovered in 1992 by Tim White in Aramis, Ethiopia (as yet largely unpublished)

  • Distinct enough to be a new species?

    • ape-like dentition

    • bipedal locomotion

    • overall hominid-like skeleton

    • small cheek teeth with thin enamel and large canines

    • arm bones are hominid-like

    • foramen magnum indicates bipedalism


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The Varied Australopithecines

  • There are two major hominid genera: Australopithecus and Homo.

  • However, in 1992 Berhane Asfaw and Tim D. White discovered substantial remains considered to be from hominids ancestral to the australopithecines; these remains have been called Ardipithecus ramidus (thus establishing a third hominid genus) and dated a 4.4 m.y.a.

  • A more recent (1995, by Maeve Leakey and Alan Walker) discovery has been named Australopithecus anamensis and been dated at 4.2 m.y.a.


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Pelves

A comparison of human and chimpanzee pelves.


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Skeletons

Comparison of human and chimpanzee skeletons.



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Dentition

Comparison of dentition in ape, human, and A. afarensis palates.


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Australopithecines

Skulls of Robust (left) and Gracile (right) Australopithecines.



Australopithecus afarensis l.jpg

apelike features (long arms, prognathic face, toothrow, brain capacity)

pelvis, leg, feet, and foramen magnum all indicate bipedalism

4.2 mya, with oldest definite specimen placed at 3.8 mya

first discovered by Don Johanson in 1974 and called “Lucy”

thought to be the “missing link” until A. anamensis was discovered 20 years later

Australopithecus afarensis


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Australopithecus afarensis brain capacity)

Left: Trail of footprints of A. afarensis made in volcanic ash, discovered by Mary Leakey at Laetoli.

Right: Close-up of footprint at Laetoli


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A. africanus brain capacity)

  • 3.5 - 2.5 mya

  • 3.8 - 4.5 feet tall, 55-130 lbs

  • ape-like tibia, grasping big toes

  • wide pelvis, parabolic tooth row

  • primitive bipedalism

  • first found by Raymond Dart in Taung, South Africa in 1925


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Map of Australopithecine Finds brain capacity)

Map of Australopithecus sites in Africa, with a focus on the East African rift valley and limestone caves of South Africa.


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Hominid Evolution brain capacity)

  • Major Homo advances:

    • Brain size

    • Better bipedalism

    • Hunting

    • Fire (H. erectus)

    • Tools

      • Oldowon (H. habilis)

      • Acheulean (H. erectus)

      • Mousterian (H. heidelbergensis)

      • Solutrean (H. sapiens)

    • Built shelters (H. heidelbergensis)

    • Clothing (H. neandertalensis)

    • Language (Neandertals?)


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Homo habilis brain capacity)

  • 612 cc brain

  • 2.3 - 1.6 mya

  • first toolmaker

  • prognathic face, brow ridge

  • probable meat-eater

  • possibly arboreal

  • discovered in 1960 by Leakeys

  • no speech

Artist’s representation of a Homo habilis band as it might have existed two million years ago.


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H. habilis brain capacity) v. H. erectus

  • Finds in east Africa indicate that Homo habilis was not very different from the australopithecines in terms of body size and shape.

  • The earliest Homo erectus remains indicate rapid biological change.

    • The fossil record for the transition from H. habilis to H. erectus supports the punctuated equilibrium model of evolution.

    • H. erectus was considerably taller and had a larger brain than H. habilis.


Homo erectus l.jpg
Homo erectus brain capacity)

  • 1891 - Eugene Dubois discovers H. erectus in Java

  • Dubois calls it Pithecanthropus erectus initially, also dubbed “Java Man”

  • finds in China called Sinanthropus

  • dates from 1.9 mya to 27,000 years B.P.

  • 994 cc brain size (compare to 612 for H. habilis)

  • Acheulean tool industry

Photograph of Nariokotome boy, an early Homo erectus found near Lake Turkana, Kenya.


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Homo neanderthalensis brain capacity)

  • discovered in the Neander Valley (Tal) near Dusseldorf, 1856

  • massive brain--about 1,400cc on average

  • large torso, short limbs, broad nasal passages

  • later remains show decrease in robustness of the front teeth and face, suggesting use of tools replaced teeth

  • retained occipital torus, some mid-facial prognathism

The skull of the classic Neandertal found in 1908 at La Chapelle-aux-Saints.


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What happened to Neandertals? brain capacity)

  • H. neanderthalensis coexisted with H. sapiens for at least 20,000 years, perhaps as long as 60,000 years

  • What happened?

    • Neandertals interbred with H. sapiens

    • Neandertals were killed off by H. sapiens

    • H. sapiens drove Neandertals into extinction by competition


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Cro-Magnon Man brain capacity)

  • Cro-Magnon humans

    • 35,000 years B.P. in western Europe to 17,000 years B.P.

    • 1,600 cc cranial capacity

    • Name comes from a hotel in France

    • Not a different species, just old Homo sapiens from Europe

Artist’s reconstruction of a Cro-Magnon man


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Homo sapiens brain capacity)

  • Archaic – 100,000 to 35,000 years BP

    • Sometimes called Homo sapiens and Homo sapiens neanderthalensis

  • Modern – 35,000 years BP to present

    • Anatomically modern

    • Sometimes called Homo sapiens sapiens


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