Evolution of
Australian Biota
Identify and describe
evidence that
Australia was once
part of Gondwana
• Together with New Guinea, it is the
only place where monotremes
(egg laying mammals) can be
found.
• There are more species of plants
to be found in the heaths of south
western Australia than all of
Europe.
• Why is Australia’s wildlife so
peculiar?
• When the platypus was first
discovered and reported in
England, scientists thought the
description of a an egg laying
mammal, with bill like a duck, and
a tail like a beaver had to be a
hoax!
Intro: Gondwana
• Alfred Wegner suggested the
theory of continental drift and that
Australia was once part of the land
mass Gondwana
• His idea was that the continents
were once a single land mass, at
then drifted apart from each other.
Evidence that supports
that Australia was once
part of Gondwana
1. Matching continental margins
• The continents do not fit neatly
together, as they have been affected
by erosion.
• Computer models of continents
including their continental shelves
resulted in a good match.
2.Fossil evidence:
Fossils of some extinct plants and Animals
have only been found in Australia,
Antarctica, South America, Africa and
India.
This shows that organisms once existed
on continents which are now separated
by oceans.
Some example include:fossils of the
Glossopteris and Gangamopteris plants
which are only found on contients of the
southern hemisphere.
3.Similarities between present-day
organisms on Gondwana continents
The distribution of organisms is consistent
with continental drift.
-Marsupial are only found in Australia,
New Guinea and south America
(handout).
-There are three similar lung fish found in
Australia, South America and Africa.
• 4.Spreading zones between continental
plates:
• According to the plate tectonic theory,
the Earth’s crust is made up of huge
plates of continental crust and ocean
crust.
• As continents are part of the plates they
drift with the plates
• The plates float on the Earths mantle.
Due to slow convection currents below
the crust the plates move. These
movements cause Earthquakes and
Volcanoes.
• Plates can be spreading,subduction or
colliding.
• 5.Position of mid ocean ridges:
• A line of ridges extends through
the worlds oceans floors. These
are known as mid-ocean ridges.
• On each side of the mid-ocean
ridges geologist noticed that the
pattern of magnetism in the rocks
were identical.