Fossil Primates 2
Dr. Bill Sellers Today's lecture will follow on from the previous
lecture and look at the last 5 million years of human evolution. In
fact, I will concentrate on the Pliocene, and leave the last million
years for later, since the human-like animal around then is very
human-like indeed, and probably is better discussed by someone who
doesn't claim to be a primatologist.
How it all MIGHT fit together
Various species in Africa from 5 to 1 mya
Africa: 2 to 1.5 mya
Africa, East Asia, South East Asia: 1.8 mya to 100,000 ya
Archaic forms from 400,000 ya, modern forms from 200,000 ya.
Africa, Asia, Europe.
East African rift valley system (1,200 miles long) associated
with mountain building, faulting and vulcanism over last few million
years. Earth movement mean sediments get exposed (Plio-Pleistocene 4 to
1 mya), and volcanic activity causes layers of volcanic ash (tuffs)
which can be dated (potassium argon, or fission tracks) accurately.
Now very important site called Aramis: Australopithecus
ramidus, 4.4 mya. Though there is argument about whether this animal
has enough derived features to be an australopithecine (need post-crania
to be sure, and post-crania needs to be found in close context with
cranial material to confirm species).
3.75 to 3.5 mya. Most famous
for the Laetoli footprints: thousands of footprints of over 20 different
species including hominins. One set of hominin tracks are of 2-3
individuals in a trail more than 25 m long - bipedal walking such as
this is considered to be characteristic of hominins
Very many fossils and artefacts.
Fossils from 3.9 to 3 mya. Most famous is Lucy (Afar Locality (AL)
288-1), a 40% complete skeleton (one of only 2 hominin skeletons earlier
than 100,000 ya). AL 333 is a group of over 13 individuals including 4
infants: a "catastrophic" assemblage perhaps.
Very thick continuous sequence
(0.5 mile thick). 2.9 to 1 mya. Very rich fauna, so useful for
biostratigraphic dating, but fossil hominins restricted to teeth and
Possibly the richest site. Approx. 1.8 mya, though there are
some much older beds (3.3 mya). Complete skulls, jaws and post-crania.
West side of Lake Turcana. 2 very famous finds: an almost
complete, 1.6 mya
Homo erectus adolescent (see later) and the so called "black
skull", a 2.4 mya robust australopithecine skull that is still causing
problems with classification!
Mini Grand Canyon. 2 mya to present, providing an excellent
sequence of fossils and artefacts, including the original robust
Unlike the East African deposits, the South African ones are
all cave deposits - piles of mineralized sediment that has fallen into
caves. They are not currently datable to any great accuracy, and the
ages are usually inferred by looking at the faunal context of the fossil
and comparing it to faunal remains from better dated sites. However,
they have produced many fossils, including some good post-cranial
material (including pelvis: important for investigating bipedalism)
Limestone mine which produced
the "Taung Child" in the 1920s. Before this, it was always thought that
the earliest humans would be discovered in Europe, or perhaps the Far
East. Consequently, it took quite a while before this discovery was
accepted for what it was.
Another set of caves in SA. (Sterkfontein was another
commercial lime works).
Not too much to say about this one. It appears to be more
primitive than the others. There's some argument as to whether it is a
hominin. It's discoverers would have us believe that it is the best
human ancestor. Some good cranial material, but no post-crania. 4.4 mya.
Best fossils from Laetoli and Hadar, including Lucy, and in
1992, a reasonably complete cranium. Primitive teeth (large canines,
parallel tooth rows); small brain (no bigger than chimp < 500 cm3);
clearly bipedal (footprints, feet, pelvis, femur); rather ape-like wrist
and pot-belly. Perhaps as much as 4.5 mya, but only certain after 4 mya.
Possible extreme sexual dimorphism, or maybe 2 contemporaneous species.
2.5 mya. Earliest is WT-17000 (West Turkana) A.
aethiopicus. Small brained (410 cm3), teeth diverge at rear
(primitive traits), but also has derived, robust australopithecine
traits: broad face; large palate; large back teeth. Intermediate between
A. afarensis and the other robusts? 2 mya A. boisei from
East Africa - "nutcracker man" - very robust; huge back teeth; very
broad face (Zinjanthropus). Also A. robustus from South
Africa - similar date. Possibly a tool user. Have tools from South
Africa, but there was a sympatric, contemporaneous Homo habilis
which may have made the tools.
Note: some authors put these animals
into a separate genus Paranthropus.
South African only. Although not much difference in overall
body size compared to robusts, has much smaller face. Has smaller
molars, but larger canines and incisors than the robusts, though still
larger than modern humans. Thought to be linked to a very different
Possibly as old as 2.4 mya. Certainly appears to be found
alongside robust australopithecines for at least 1 my. Has a bigger
brain (600 - 800 cm3) and different dental proportions. Found both in
East and South Africa. Again there is dispute as to whether there are 2
species, or if there is sexual dimorphism. KNM-ER 1470 H.
rudolfensis or just male H. habilis?
Also referred to as the Homo erectus people because we
are very worried about this classification!
This is a group that
covers many of the original early hominin finds (Pithecanthropus
for Java; Sinanthropus for China;
Heidelbergensis perhaps). The East African finds are accurately
dated to 1.6 to 1.8 mya. The Javanese ones may be as old. The possible
European finds (including last year's Boxgrove Man) may be as early as
0.5 mya. This suggests a very early migration out of Africa.
bigger brain (750 - 1250 cm3)
Larger body (cf. Nariokotome boy),
though still probably sexually dimorphic. Adults probably > 6 feet
tall. Heavy build too.
Distinctive cranial shape: thick bone
(esp. Asian forms); large brow ridges (supra-orbital tori); nuchal torus
Keeling on top of skull
Teeth very like humans, but with
slightly larger teeth in early forms, and "shovel" shaped incisors.
Used fire and stone tools
6 sites with some recent
controversial reassessment of dates suggesting (if true) that the
migrations must have been very much earlier.
Originally "Dragon's Teeth"
used in Chinese medicine. Several sites. Managed to lose quite a few
fossils when they were being moved before WW2 to keep them from the
Fossil sites in East and South
Africa have revealed H. erectus. However, there are also sites
in North Africa, in Algeria and Morocco. However, not all these remains
are necessarily H. erectus - they might be what's termed as
"archaic Homo sapiens".
Early finds in the Levant
(perhaps over 1mya), and newer finds in Northern Europe (France, Germany
and England). However these may be archaic
Put up summary tree with
dates, and vague linkages (P17 HDA)
This page is maintained by Steve Paxton