are the most
famous animals of Australia.
They get their name from marsupium - the pouch.
Kangaroo. Poster by AllPosters. Click on thumbnail to buy
Their young are
born so early that they need to complete their embryonic development
while nursing, which in most species occurs in their mother’s pouch. A
for example is about the size of a honeybee when it is born only 33
days after fertilisation.
Koala. Poster by AllPosters. Click on thumbnail to buy
Marsupials and Continental Drift
Marsupials are one of the largest and most successful groups of native
in Australia. The reason for this unique fauna is Australia’s long
isolation from other continents. When the super-continent Pangaea broke
up about 200 million years ago, reptiles still ruled the world.
successful - although small mammals existed, they
never got a chance to dominate the Animal Kingdom.
Once the dinosaurs
by what is
believed to be a sudden climate
change caused by
a meteorite or a volcano (theories vary), Pangaea
had already drifted apart to form two continents: the northern
Laurasia, and the southern Gondwana. All of a sudden mammals got the
chance to develop into many different species, and it so happened that
on Laurasia, they developed into placental
animals, and on Gondwanaland
Possum. Poster by AllPosters. Click on thumbnail to buy
Marsupials and Placental Animals
When the Gondwana continent broke up, India got attached to Asia,
Africa to Middle
East and South America to North America. Marsupial and placental
animals were joined, and marsupials got extinct.
was never connected to any other continent, and here they survived.
South America still has a few species of opossums, but
generally placentals were more successful, or perhaps because in
placental world there were more large predators (there are no large
carnivorous animals in Australia), marsupials didn’t survive.
Wombat. Poster by AllPosters. Click on thumbnail to buy
Marsupial Animals and Convergent Evolution
It is interesting how placental and marsupial animals developed in
separation. Animals that fill similar niches in both hemispheres look
remarkably similar, although they have developed totally independently.
Look at Australian
animals - a marsupial mouse looks like a mouse of the
Northern Hemisphere, a marsupial mole has got features like
a mole of the Northern Hemisphere, and a sugar glider
looks like a flying squirrel. Just because they lived in similar
environments and used similar strategies they developed similar
features in what is called convergent evolution.
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