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Early Hominins

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4-3 mya bipedal although these animals probably also were comfortable in the trees ... Stone tools and hunks of rock. Provenience ... – PowerPoint PPT presentation

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Title: Early Hominins


1
Early Hominins
  • Part 2

2
AustralopithecinesThe earliest Hominins
  • East African fossil finds
  • 4-3 mya bipedal although these animals probably
    also were comfortable in the trees
  • From Ethiopia, Tanzania, Kenya
  • Great Rift Valley
  • Environment has changed
  • Hadar in the Afar depression of Ethiopia now dry,
    used to be wooded
  • Laetoli in Tanzania bipedal footprints _at_ 3.6 mya
    in mud of a wetland area

3
Maps of Africa (see http//81.0.149.237/frie_med
ier/Map_of_Africa.jpg and http//www.worldatlas.co
m/webimage/countrys/aflnd.htm)
4
AustralopithecinesThe earliest Hominins
  • South African fossil finds
  • All the main finds from South Africa
  • Taung child
  • Raymond Dart in 1925
  • The first Australopithecine ever discovered
  • Australopithecus africanus
  • Dates to about 3-2 mys
  • Mrs. Ples, also A africanus confirmed the find
    was a bipedal hominid

5
Maps of Africa (see http//81.0.149.237/frie_med
ier/Map_of_Africa.jpg and http//www.worldatlas.co
m/webimage/countrys/aflnd.htm)
6
Gracile Australopithecines A anamensis
  • Australopithecus anamesis
  • Kenya
  • 3.9-4.2 mya
  • Small hominin
  • Teeth like A. afarensis
  • Long bones suggest bipedalism
  • Homo from the neck down and head like
    Australopithecus
  • https//www.msu.edu/heslipst/contents/ANP440/anam
    ensis.htm

7
Gracile Australopithecines A afarensis
  • Australopithecus afarensis
  • 4-3 mya in East Africa
  • Laetoli, Tanzania
  • Teeth and jaws
  • Footprints3.6 mya
  • Hadar, Ethiopia
  • Lucy40 of skeleton found
  • Pelvis shows she was bipedal
  • 3.2 mya in semi-arid savanna

8
Gracile AustralopithecinesA afarensis
  • Australopithecus afarensis differs from A
    africanus in terms of date (earlier) and location
    (E Africa)
  • Incisors and canines large and tooth rows
    converge
  • Often has sagittal crest and temporo-nuchal crest
  • Largest males were 150 cm tall and cranial
    capacity was about 415 cc
  • (http//anthropology.si.edu/humanorigins/ha/afar.h
    tml and (https//www.msu.edu/heslipst/contents/AN
    P440/afarensis.htm)

9
Gracile AustralopithecinesA africanus
  • Rounded brain case, well-develop forehead and
    moderate brow ridges, projecting face
  • Cranial capacity between 428cc and 485cc
  • Adults 105-135 cm tall
  • Chinless jaw of Miocene apes but broad incisors
    and short canines as well a relatively small
    molarsdental function similar to humans
  • Broad pelvis, lumbar curve and hip joint and
    femoral bone analysis suggest bipedalism
  • 3-2 mya so more recent than A afarensis

10
Gracile AustralopithecinesA africanus
  • The Taung Child A africanus
  • Discovered in 1925 by Raymond Dart
  • Child less than 3 years old
  • Dates to about 3.2 mya
  • Foramen magnum position and short incisors and
    canines were human-like rather than ape like
  • Biped
  • Mrs.Ples found in 1940s confirmed the discovery
    of A africanus as a biped
  • (http//anthropology.si.edu/humanorigins/ha/afri.h
    tmlhomo and https//www.msu.edu/heslipst/content
    s/ANP440/africanus.htm)

11
Robust Australopithecines
  • Date between 2.5 mya and 1 mya in East Africa and
    South Africa
  • A boisei (http//anthropology.si.edu/humanorigins/
    ha/bos.html)
  • East African
  • 2.3-1.3 mya
  • A robustus (http//anthropology.si.edu/humanorigin
    s/ha/rob.htm)
  • South African
  • 1.8-1 mya
  • Should they all be called Paranthropus rather
    than Australopithecus?

12
Robust Australopithecines
  • In comparison to gracile australopithecines they
    had
  • Thick jaws
  • Large molars and premolars
  • Small incisors
  • Massive muscle attachments for chewing
  • Large sagittal crests for chewing
  • A boisei more extreme than A robustus in these
    features
  • Cranial capacity of both species of robust
    australopithecine was 490-530cclarger than
    gracile forms
  • Body size similar to A africanus so relative
    brain size was larger than A africanus

13
Robust AustralopithecinesA robustus
  • Discovered in South Africa in 1938 when it was
    given the name Paranthropus in contrast to A
    africanus
  • Large teeth and jaw and flat face
  • 1.8-1 mya
  • A robustus ate vegetable foods but new studies do
    not rule out other foods
  • Not ancestral to Homo species
  • (http//anthropology.si.edu/humanorigins/ha/rob.ht
    m)
  • (https//www.msu.edu/heslipst/contents/ANP440/ro
    bustus.htm)

14
Robust AustralopithecinesA boisei
  • Mary Leakey and Louis Leakey discovered A boisei
    at Olduvai Gorge in 1959
  • Leakey called the new fossil Zinjantropus
  • Now placed in the Australopithecines
  • Extremely robust facial features
  • Molar teeth, expanded premolars, massive and
    thick jaw, large sagittal crest
    (http//anthropology.si.edu/humanorigins/ha/bos.ht
    ml) and (https//www.msu.edu/heslipst/contents/AN
    P440/boisei.htm)
  • 2.3-1.3 mya in dry, open environment
  • Questions about robust Australopithecines
  • Some lived at same time as Homodid they make and
    use tools found after 2.5 mya?
  • Are similarities in robust forms (ie A robustus,
    A boisei and later H erectus due to evolutionary
    convergence or ancestral linkages?

15
Stone tools and hunks of rock
  • Provenience
  • Kind of rockcan be flaked and will lastflakable
    and durable
  • Bilateral flakingboth sides of stone struck to
    make and cutting edge
  • Retouching
  • Striking platform

16
Lines of Descent
  • See page 180 of the text and http//anthropology.s
    i.edu/humanorigins/ha/a_tree.html
  • Between 3 and 1 mya there were at least two
    hominin lines
  • Robust australopithecines became extinct about 1
    mya and were not ancestral to modern humans
  • Homo habilis was in direct lines of descent to H
    sapiens

17
Themes
  • Complex jig-saw puzzle with pieces spread over
    100s of miles and millions of years
  • Lots of ego involved in this work!
  • Various species of Australopithecus existed
    together and in sequence
  • A afarensis most likely ancestor of Homo
  • Bipedal but not yet making toolsalso possibly
    partially arboreal in some species
  • Sexual dimorphism especially in the robust forms
  • Increase in cranial capacity indicating larger
    brains over time
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