Australia's Ancient Giant Wombats
Made Long Migrations (text in english)
The 3 tonne (3.3 US ton) wombats
that roamed Australia during the Ice Age undertook great seasonal migrations,
presumably for food. This is the first time this behavior has been found in
marsupials, despite being common among large vegetarian mammals.
Australia's environment was once
dominated by diprotodons, giant relatives of wombats that were comparable to
rhinoceroses in size. They were so enormous and so numerous that their loss
probably had a large impact on the continent. But since scientists have never
had the chance to study one directly, we know little about their behavior.
Dr Gilbert Price of the University
of Queensland has filled in one piece of the puzzle, however, by examining the
fossilized incisor of Diprotodon optatum, the largest marsupial of all time.
“It goes back to that old saying
‘you are what you eat’, because the chemicals of the food they consumed became
part of their teeth,” Price said in a statement. “But it’s also true that ‘you
are where you ate’, especially if you are a plant eater, because the
geochemistry of the soils where plants grow also become fixed into a
herbivore’s tooth.”
By analyzing the enamel layers of
one D. optatum individual, Price found that the species migrated at least 200
kilometers (120 miles) annually across the Darling Downs. The findings are
reported in Proceedings of the Royal Society B.
Diprotodon jaws were huge to consume
the vast amounts of grass they needed to survive, as Gilbert Price demonstrates
here. University of Queensland
Although small birds migrate 100
times further, seasonal migrations are usually restricted to large species of
mammal. Large beasts are in danger of eating all the locally available food,
particularly if, like D. optatum, they live in herds. The need to keep moving
to find fresh pastures could easily have led to regular migrations influenced
by rainfall patterns.
We don't yet know whether other
members of the diprotodontid family did the same thing, but the new discovery
is significant.
“Why this is exciting is, although
marsupials like kangaroos might migrate on a nomadic basis, there are none
today that follow set seasonal patterns,” Price said.
He is particularly interested in
what happened when the diprotodons died out, as it might indicate what to
expect if other continents lose their migratory grazers. It is likely that
diprotodon extinction affected the landscape of Australia and killed off
predators, but we don't know for sure.
Ecologists have found that, in areas
where cattle have replaced zebra or antelopes, it is best to try to replicate
migratory patterns, where grasslands are eaten intensively for short periods of
time. This has yet to be applied to Australian ecosystems, which were not
thought to be adapted to this particular grazing pattern.
Πηγή
: http://www.iflscience.com/plants-and-animals/australias-ancient-giant-wombats-made-long-migrations/
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Giant Australian marsupials were like no other from The University of Queensland on Vimeo.
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