Fossil Primates 2
Dr. Bill Sellers
Introduction
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.Lecture Outline
OrientationThe Sites
The Fossils
The Species
How it all MIGHT fit together
Orientation
Australopithecines (Southern Apes)
Various species in Africa from 5 to 1 myaHomo habilis (Handy man)
Africa: 2 to 1.5 myaHomo erectus (Erect man)
Africa, East Asia, South East Asia: 1.8 mya to 100,000 yaHomo sapiens
Archaic forms from 400,000 ya, modern forms from 200,000 ya. Africa, Asia, Europe.Australopithecines
The Sites and Fossils
East Africa
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.Middle Awash
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).Laetoli
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 homininsHadar
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.Omo
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 bone fragments.East Turkana
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 Turkana
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!Olduvai Gorge
Mini Grand Canyon. 2 mya to present, providing an excellent sequence of fossils and artefacts, including the original robust australopithecine cranium.South Africa
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)Taung
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.Sterkfontein, Kromdrai & Swartkrans
Another set of caves in SA. (Sterkfontein was another commercial lime works).Makapansgat
Another cave...The Species
A. ramidus
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.A. afarensis
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.
A. robustus, A. aethiopicus, A. boisei (robust austrlopithecines)
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.
A. africanus (gracile australopithecines)
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 diet.Homo
Homo habilis (early Homo)
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?Homo erectus
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.
Much 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
Java
6 sites with some recent controversial reassessment of dates suggesting (if true) that the migrations must have been very much earlier.Peking
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 Japanese.Africa
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".Europe
Early finds in the Levant (perhaps over 1mya), and newer finds in Northern Europe (France, Germany and England). However these may be archaic sapiens too.Summary
Put up summary tree with dates, and vague linkages (P17 HDA)This page is maintained by Steve Paxton