1. HISTORY OF LIFE
ON EARTH

2. PALAEONTOLOGY:
• The study of fossil records to
discover the history of life, ancient
climates and environments

3. THE FORMATION OF MINERALISED
FOSSILS
Fossils are formed in a number of different ways:
Most are formed when a plant or animal dies in a watery environment.
And is buried in mud and silt.
Soft tissues quickly decompose leaving the hard bones or shells behind.
Over time sediment builds over the top
And hardens into rock.

4. THEFORMATION OF MINERALISED
FOSSILS continuous
As the encased bones decay, minerals seep in replacing the
organic material cell by cell in a process called "petrification."
Alternatively the bones may completely decay leaving a cast of the
organism.
The void left behind may then fill with minerals making a stone
replica of the organism.

5. THE WAY MINERALISED FOSSILS ARE
FORMED

6. DATING OF MINERAL FOSSILS
Method used to determine the age of fossils or the strata
(layer of sediment) in which they are found.
Example of methods;
o Relative dating methods
oAbsolute dating methods like Radioactive dating.

7. The Law of Superposition
oStates that the older layer lies underneath the younger
layer in undisturbed contexts.
oDeeper layers are older than fossils from layers closer to
the surface of the earth

8. CONTINUATION OF FOSSIL DATING
• Scientists use the results from fossil dating to make
inferences about the age of a fossil, which can be used to
determine which organisms lived when, and when did
some organisms became extinct.

9. KEY EVENTS IN LIFE’S HISTORY IN
SOUTHERN AFRICA
• There were a few key events in life’s history which there
is evidence from southern Africa
• Origins of the earliest forms of life: evidence of fossilized
bacteria (stromatolites) from caves found in the Barberton
district, Mpumalanga and many other caves.

10. THE EVENTS
Soft bodied animals in Namibia
Early land plants in the Grahamstown area.
Forests of primitive plants such a Glossopteris which form most of the coal
deposits in southern Africa.

11. Mammal like reptiles in the Karoo e.g.
Thrinaxodon
Thrinaxodon

12. Dinosaurs found in the Drakensberg and
Maluti mountains e.g. Euskylosaurus from Lady
Brand in the Free State and cone bearing plants
Euskylosaurus

13. Primitive Cone-bearing plants

14. First mammals found in Eastern Cape and
Lesotho

15. Humans fossil found in Gauteng, Free State,
Kwazulu Natal, Western Cape and Limpopo

16. CONTINUATION OF THE EVENTS
• Part of the skeleton of Australopithecus sediba from
the Malapa site in South Africa. Two partial
skeletons unearthed in a cave belong to a
previously unclassified species – which could be an
early human ancestor – dating back almost 2
million years

17. THE EVIDENCE OF
AUSTRALOPITHECUS
• Sterkfontein's first piece de resistance: the Australopithecus africanus Mrs Ples
(now believed to be a Mister Ples), dating back 2.5-million years, found by
Robert Bloom in 1947. The fossil provided proof that Australopithecus could
be classified as a member of the Hominidae (the family of humans) and
established Africa as the Cradle of Humankind.

18. REFERENCES
• Campbell, N.A., Reece, J.B., Urry, L.A., Cain, M.L., Wasserman, S.A., Minorsky, P.V., Jackson, R.B.
2010. Biology Eighth Edition. Pearson International. 16:305-336.
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• Russell, P.J., Hertz, P.E., McMillan, B. 2012. Biology: The dynamic Science. Brooks-Cole Cengage
Learning. 14: 286-302.
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• Starr, C., Taggart, R., Evers, C. and Starr, L. 2013. Biology: The unity and diversity of life. BrooksCole Cengage Learning. 8:124-132.
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