Overview of Fossil Hominids Geological Time Scale

Geological Time Scale
Overview of Fossil Hominids
Period
Quarternary
Alan R. Rogers
Tertiary
March 14, 2011
Epoch
Recent
Pleistocene
Pliocene
Miocene
Age
(myr)
0.01–0
1.7–0.01
5–1.7
23–5
Events
agriculture, complex societies
genus Homo
genus Australopithecus
genus Sahelanthropus
Hominin sites of the Pliocene and
early Pleistocene
Early middle
Pleistocene.
Archaic
H.
sapiens
colonized
Europe.
Early upper
Pleistocene
137–10 kya
Miocene hominins
Species
Sahelanthropus tchadensis
The Toumai skull
Age
6–7 mya
EA
SA
CA
*
CA: Central Af; mya: millions of years ago.
Gracile hominins of the Pliocene
Species
Ardipithecus ramidus
Australopithecus anamensis
Australopithecus afarensis
Australopithecus africanus
Age
4.4 mya
4.2–3.9 mya
3.9–2.8 mya
3.5–2.3 mya
I
6–7 mya
I
Central Africa
I
Sahelanthropus tchadensis
I
brain: 320–380 cc
I
Ancestral to humans? to chimps?
I
Ardipithecus ramidus
I
4.4 mya
I
East Africa
I
Small brain
I
Intermediate between hominins and
earlier apes
Ardipithecus ramidus
EA
*
*
*
*
SA
CA
*
EA: East Af; SA: South Af; CA: Central Af; mya: millions of years ago
Ardipithecus ramidus
Ardipithecus ramidus
I
Ardipithecus ramidus
I
Small brain
I
Small canines
I
Ardipithecus ramidus
I
Opposable big toe, flexible wrist
I
Walked upright; also climbed on branches
The “Lucy” skeleton
I
3.2 mya
I
East Africa
I
I
Mrs. Ples
Australopithecus afarensis
most complete australopithicine skeleton
Robust hominins of the Pliocene
Species
Australopithecus aethiopicus
Australopithecus boisei
Australopithecus robustus
I
Australopithecus africanus
I
2.3–2.8 mya
I
Sterkfontein, S Africa
E African robust australopithicine
Age
2.7–2.3 mya
2.2–1.3 mya
1.8–1 mya
EA
*
*
SA
CA
*
EA: East Af; SA: South Af; CA: Central Af; mya: millions of years ago
I
A. afarensis and H. sapiens
I
afarensis walked like we do
(bipedal locomotion)
I
had a chimpanzee-sized
brain
I
Australopithecus
boisei
I
1.5 mya
I
E Turkana, E Africa
I
massive jaw muscles
I
huge molars
Africanus had big teeth.
Boisei had even bigger teeth.
I
Australopithecus africanus
I
Australopithecus boisei
I
3.0–3.3 mya
I
1.5 mya
I
S Africa
I
Lake Natron, Tanzania
I
Thick molars
I
huge molars
I
Thick enamel
I
extremely thick enamel
I
Short canines
I
massive cheekbones
I
enormous jaw muscles
I
especially on robust forms
On robust forms, jaw muscles reached to top of head.
The genus Homo
Species
Homo habilis
Homo erectus
archaic Homo sapiens
(incl Neandertal)
a.m. Homo sapiens
Age
1.9–1.6 mya
1.8–0.4 mya
A
f
*
*
E
u
A
s
*
*
400–40 kya
90–0 kya
*
*
*
*
*
*
A
m
O
z
*
*
Af: Africa; Eu: Europe; As: Asia; Am: Americas; Oz: Australia; mya: millions
of years ago; kya: thousands of years ago.
I
big molars
I
thick enamel
I
small diastema means small canine
Homo habilis (sm brain & teeth)
I
the old Homo habilis is now
2 species
I
H. rudolphensis (on left):
large brain; large teeth
I
H. habilis (on right): small
brain; smaller teeth
Homo rudolfensis (lg brain & teeth)
Homo ergaster (↑ brain, ↓ teeth)
I
early African Homo erectus
I
restricted to Africa;
1.8–0.6 mya
I
also called Homo ergaster
I
larger brain (900 cc)
I
small gut
I
smaller cheek teeth
The Nariokotome skeleton
I
early African H. erectus
I
12 years old
I
5’4” tall (like a modern human)
I
body proportions like ours
I
small teeth
I
powerful muscles
I
I
Between 800 and 500 kya
there appeared hominins
with higher, more rounded
crania and larger brains
I
archaic Homo sapiens
I
includes Neanderthals
I
archaic H. sapiens or early
modern
I
90–190 kya
Asian Homo erectus
Shanidar, Iraq
Jebel Irhoud
I
Neandertal
Tiny hominins of Flores Island, Indonesia
early modern Homo sapiens
I
Homo floresiensis
I
Stood about 1m high.
I
Brain 380 cc.
I
18 kya
I
Genetic deformity?
I
Island dwarfism?
Summary
I
Hominins are the bipedal apes in that portion of the
evolutionary tree that includes humans but not chimpanzees.
I
Sahelanthropus was a Miocene ape that may have been
ancestral to humans, to chimps, or to both. Not clear whether
it walked upright.
I
In the Pliocene, there was a variety hominin species. They
walked upright but had chimp-sized brains.
I
Larger brains began to appear at the end of the Pliocene, with
the advent of Home habilis and Homo erectus.
I
In the early Pleistocene, Homo erectus expands out of Africa
and throughout Europe and Asia.
Summary (cont)
I
The species called archaic Homo sapiens appears about 400
kya. It retains the strong brow ridges and receding chin of H.
erectus, but has a larger brain.
I
Anatomically modern Homo sapiens appears about 100 kya
and spreads throughout the world about 50 kya.
I
erectus/ergaster’s
ribcage less conical
I
implies a smaller gut
I
implies a high-quality
diet