4. Glossopteris
1.Archean
(cyanobacteria)
2.Ediacarans
(Metazoa)
12.Cradle of
Humankind
11.Mammals
13. Antetonitrus
4. Glossopteris
11.Mammals
6.Therapsids
Mammal-like Reptiles
5. Coelacanth
3.Diapsids
Reptiles+Dinosaurs
ACTIVITY: MAP KEY EVENTS IN LIFE’S HISTORY IN SOUTHERN
AFRICA
The text on the following pages describes some of the key events in Life’s History for which
there is evidence in Southern Africa.
1. When you read each description in the text that follows, identify the places where
evidewnce has been found and mark them on the map.
2. For each place you have marked, [rovide a brief description of the event that
happenend.
FORMAL ASSESSMENT TASK: FOSSILS IN SOUTH AFRICA
BACKGROUND:
South Africa is home to many different kinds of fossils, including living fossils.
1. FOSSILISED BACTERIA IN BABERTON AREA
The microbes broke down volcanic glass to extract nutrients
The rocks were altered after they were formed but the burrows were preserved
Stromatolite formation near Baberton area
The earliest signs of life are about 3 500 million years old. Some of the most ancient
fossils that are known to exist have been found in the rocks from the Baberton area of
Mpumalanga. They are more than 3000 million years old These tiny fossils look like
modern blue-green bacteria. Later other types of blue-green algae grew that formed a
mat in shallow water. These are called stromatolitesand can be found in the ancient
rocks near Baberton.
2. SOFT BODIED ANIMALS IN NAMIBIA AND THE NORTHERN
CAPE
At the end of the Precambrian there were two kinds of simple animal life. The ediacaran
animals were soft-bodied animal-like creatures that were unrelated to anything we see
today. Ediacaran animals died out about 450 million years ago. Fossils of these ancient
forms of life have been found in Namibia and the Northern cape, and also in Europe and
North America.
EARLY LAND PLANTS IN GRAHAMSTOWN AREA
By the end of the Devonian period of the Palaeozoic era there were more club mosses,
ferns and horsetails, which are all plants that had specialised cells for carrying water and
nutrients. Some of their relatives are alive today. There are well preserved fossils of
these club mosses and the simple relatives of conifers in the late Devonian rocks near
Grahamstown in the Eastern Cape.
3. FORESTS OF PRIMITIVE PLANTS SUCH AS GLOSSOPTERIS NEAR
MOOI RIVER AND ESTCOURT
Near the end of the Palaeozoic Era, in the Permian period, Southern Africa had moved
away from the South Pole. When the climate became warmer, the land became covered
in new types of cone-bearing plants. The best known plant in the Southern hemisphere
from that time is a “seed-fern” tree called the Glossopteris. Fossils od Glossopteris tree
trunks are common near Estcourt and Mooi River in Kwa-Zulu Natal. Plants like these
formed the huge coal deposits that are mined in South Africa today. The first true seedbearing plants, which were simple conifers, appeared at the very end of the Permian
Period.
4.
THE COELACANTH AS A LIVING FOSSIL OF THE GROUP THAT
IS ANCESTRAL TO AMPHIBIANS
The coelacanth is a “living fossil”; it is similar to 350 million year old fossils but is
still alive today.
The coelacanth is a lobe-finned fish from the Permian Period that was once thought
to be extinct and was only known as a fossil. Sometimes scientists find some animals
and plants that have not changed for milliobs of years. They call them “living
fossils”. When a living fossil is found, it shows us that palaeontologists were
probably correct when they described what the fossils must have been like. The
coelacanth was known as a fossil and in 1938 it was discovered to be a living animal
too.
On 22nd December 1938, a South African fishing boat netted a large fish with deep
blue scales and fins on short legs. Marjorie Courtenay-Latimer, who worked at the
East London Museum, saw the fish and sent a drawing to Professor J.L.B. Smith, a
world authority on fish, at Rhodes University, Grahamstown. He recognised it as a
fossil fish from rocks up to 350 million years old. It was thought to have been extinct
for at least 65 million years. A second coelacanth was found in 1952 in the Comores
Islands. Many have been found since then. They have even been filmed walking on
their stumpy fins. Recently, a different species of Coelecanth has been found near
Indonesia, and another population has also been found near Sodwana Bay on the
Kwazulu-Natal north coast.
5. MAMMAL-LIKE REPTILES IN THE KAROO
Reptiles diversified and spread as the most successful and largest land vertebrates in the
Permian Period. One important group was reptiles with some mammal features called
Therapsids. Thrinaxodon and Lystrosaurus were small therapsids that grew to about 50cm
long. Fossils of these mammal-like reptiles have been found in the Karoo.
6. DINOSAURS
The special type of reptile called a dinosaur appeared and spread during the Triassic
Period of the Mesozoic Era. A South African example of a dinosaur is Euskelosaurus
browni. It was one of the first dinosaurs discovered in Africa. It lived in the area now
called the Eastern Cape and fossils have been found near Lady Grey.
Later, during the Jurassic Period many different kinds of dinosaurs evolved. They were
the dominant form of animal life on Earth. One of the best places in the whole world to
look for dinosaur fossils is the sedimentary rocks of the Drakensberg Mountains and
Maluti Mountains of southern Africa.
Fossils of ferns and cone-bearing conifers have also been found in the same areas as the
dinosaurs.
7. FIRST MAMMALS
Megazostrodon – first mammal during the Jurassic period. Mammals could not dominate
during the reign of the dinosaurs. They were huge!
The first true mammals appeared during the Jurasic Period of the Mesozoic Era. They
were small, about the size of a mouse and lived side by side with the dinosaurs. South
Africa is the only place in the world where there are fossils that show changes from the
earliest Therapsid (mammal-like) reptiles from the Karoo rocks of the Permian Period to
the first true mammals from the Drakensberg rocks in the Eastern Cape and Lesotho.
PREHUMANS
The Homonids are the “human-like” Anthropoids. They diversified from the apes
between 8-10 mya. The apes lived in tropical forests, while the homonids lived in
woodlands and savannah. About 4mya, several different species of Homonids with large
brains appeared in Africa. Then, more than 2mya some Homonids with very large brains
and the ability to use tools evolved in the south. These homonids were not humans, but
are sometimes called prehumans. These prehumans are in the genus Australopithecus.
The modern human Homo sapiens appeared in Africa about 200 000 years ago and
spread all around the Earth. Many people believe that the eastern side of Africa and
South Africa are the original home of humans.
8.
Australopithecus Africanus
Ron Clark with Little Foot and (right) Mrs Ples
Some of the earliest remains have been found at the Cradle of Humankind World
heritage Site. Skulls and other bones of nearly 2 million years old have been founf here
at parts stretching from Gauteng, Limpopo and the North West.
9. Australopithecus Sediba
Prof Lee Berger with “Karabo”
In 2008 a partial skeleton was found at Malapa near Sterkfontein in the Cradle of
Humankind. These bones are from a prehuman that was more advanced thyan
Autralopithecus Africanus and may have been an early ancestor of modern humans.
10.
EARLY FORM OF HOMO
A skull of an early Homo have been found at Florisbad, north of Bloemfontein in the Free
State.
11.
HOMO
The remains of people that are almost the same as modern humans, but 200 000 years
old, have been found at Elandsfontein and Klasies River Mouth in the Western Cape.
12.
HOMO
The remains of people that are about 100 000 years old have been found at Border Cave
in Kwazulu-Natal and at Die Kelders in the Western Cape.
Taken and adapted from: Shuters Top Class Life Sciences Grade 10 Learner Book (CAPS
approved)