Origin of the hominodea Flashcards
Raymond dart’s discovert
- 1925 Discovery of Taung boy
- Brain small but more human than ape
- Small human-like canine teeth
- Bipedal (foramen magnum central) located under skull when more bipedal
How can you tell if an animal was bipedal from the skull morphology?
- foramen magnum central
- Located under skull when more bipedal
What is the Foramen magnum central?
- Hole at the back of the skull that attaches to the spinal column
- When bipedal, hole is located underneath skull
What are the robust and gracile forms of Australopithecus?
Robust: A.robustus (more heavily built)
Gracile: A.africanus
Age of A.robustus?
2.0 - 1.0 Ma
What are the major australopithecine sites?
- Limestone caves near Johanneberg
- Various other cave systems/sink holes across Africa
- Rift Valley
What was the Young swartkran (australopithicine) specimen?
- Dragged into cave my leopard
- Teeth marks in skull
- Missing back of skull
Leakey Family and fossil collectors
when/where was A.boisei (robust) found
- Found in Olduvai Gorge in Tanzania in 1959
- Discovered by Mary Leakey
- 1.75 Ma
- Ridge on skull where large jaw muscles were attached showing they had a strong bite.
1960-1963 Homo habilis. Why did this discovery cause controversy?
- Discovered by Leakey’s team
- Debated that it wasn’t a homo
- 1.75 Ma
- Upset the linear evolution of hominins
- Genus homo needed to be redefined
- Existed at the same time
Homo and Australopithecines were around at the same time
- Different hominins coexisting
- Star wars bar scenario
More A.boisei discovered
- In lake Turkana, Kenya
- 1969
- Rift valley
- Sedimentary piles in rocks
- Lake contracts and expands depending on climate (interglacial/glacial)
A. afarensis: Lucy
- 1970
- Very well preserved - almost whole skeleton
- Small
- > 3 Ma
A. afarensis Footprints
- Laetoli, Tanzania, 1978
- Volcano ash blanketed the ground
- Footprints preserved in ash
- Two sets next to eachother
- Can tell how they walked
A. aethiopicus
- from Omo, Ethiopia
- 1980’s
- 2.6 Ma
- Large jaw muscles
- Robust
How many accepted species of Australopithecenes are there?
14
What is special about the rift valley?
- Perfect place for preservation
- Are there fossils everywhere that are just not conserved?
- Findings in Chad suggest this
- Is our thinking influenced by a huge bias in the fossil record?
What were the Australopithecines and how did they live?
- Between 3-2 Ma in Africa at least 6 hominin species co-existed
- Either sharing the same habitat or occupying different habitats.
- They were either Australopithecines or Homo.
- They inhabited a mixture of environments: plains; mixed plains/woodland; forest; lake side.
What do we know about the Australopithecines?
- Modified dentition
- Curved phalanges
- Orientation for arm - can have above head for a long time
- Arm can move around more
- Sexual dimorphism - height and weight differ between male and female
How did Australopithecines walk?
- Bipedal
- Walked in a bent knee bent hip style
- Probably spent a lot of their time in trees
What do the teeth of australopithecenes show about diet?
- Compare tooth ware between fossils and current animal diets
- Large jaw mucles on robust forms
- Robust ate roots etc
Did Australopithecines use tools?
- Yes/maybe
- Tools have been found that are thought to have been before homo evolved
- Suggested that some Australopithecines used / made tools
What is the oldest hominids species described?
- Sahelanthropus tchadenis
- 6 - 7 Ma (chad)
