Australia
is the kingdom of marsupials, home to furry kangaroos, koalas and wombats. The
continent has so many marsupials, it raises the question: Did these
pouch-bearing mammals arise Down Under?
The
answer is an unqualified (or "un-koalafied") no. Marsupials were
around for at least 70 million years before they made it to Australia,
according to Robin Beck, a lecturer in biology at the University of Salford in
the United Kingdom.
"Marsupials
absolutely categorically did not originate in Australia," Beck told Live
Science. "They are immigrants."
In
comparison to most mammals, marsupials are odd. Unlike placental mammals, such
as humans, dogs and whales, marsupials give birth to relatively underdeveloped
young that continue to grow a ton in the mother's pouch.
"The
young are born alive, but they're very poorly developed," Beck told Live
Science. "They basically crawl to their mother's nipple, which is
often in a pouch, and they basically clamp on the nipple and stay
there, feeding on their mother's milk for long periods of time — usually,
several months."
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