Fanged Kangaroos Lived A Lot More
Recently Than We Thought (text in english)
Millions of years ago some kangaroos
had viciously long canine teeth, at least relative to their small size.
Discoveries at the famed Riversleigh World Heritage area in Australia reveal
less time separates us from these fearsome fangs than we thought, although we
still don't really know what they were for since their owners were just as
herbivorous as their modern equivalents.
The kangaroo family appears an
exception to the claim that “everything in Australia is trying to kill you”.
Sure the larger members can deliver a vicious kick, but mostly they're friendly
live-and-let-live types. However, they once shared the continent with relatives
called balbarids, large-fanged members of the same superfamily.
Palaeontologists are interested in
the parallel evolution of the two kangaroo families, and why the fanged version
eventually went extinct. Ideally, this might teach us something about dangers
to modern-day kangaroos, 21 of which are endangered or vulnerable.
Kaylene Butler, a PhD student at the
University of Queensland, said in a statement; “Currently, we can only
hypothesize as to why balbarids became extinct – the original hypothesis
related to events during a change in climate 15 million years ago.” Butler has
punctured that theory by announcing in Palaeogeography, Palaeoclimatology,
Palaeoecology the discovery of balbarid specimens from 10 million years ago – 5
million years after the events thought to have caused their extinction.
Since North Queensland didn't have
climatic shifts 10 million years ago like the ones 5 million years earlier, the
question of what caused the balbarid extinction remains unresolved. Since
fangless kangaroos appear to have occupied a similar ecological niche, one
possibility is that they became better adapted than their fanged cousins,
driving the balbarids out.
Butler told IFLScience that
balbarids and modern kangaroos shared a common ancestor. Unfortunately, there's
a gap in the Australian fossil record, sometimes known as the fossil dark ages,
around the time this occurred, so we don't know what this common ancestor was
like. When the fossil record resumes, tiny (around 1 kilogram or 2 pounds)
fanged and fangless kangaroos are found. Over the following 15 million years,
both grew to around 12 kilograms (26 pounds) before the balbarids disappeared.
The fangs' purpose remains a
mystery. Butler explained to IFLScience that we have insufficient fully intact
skulls to determine whether the males possessed larger fangs than the females,
suggesting they were used for mating displays and fights, like in modern musk
deer. Alternatively, they may have been predator defenses or for digging in the
dirt for fungi.
Perhaps if they had survived, the
balbarids would have grown to the size of modern red kangaroos – or even their
giant ice age predecessors, making the continent even more intimidating.
A skull of the fabulously named
Balbaroo fangaroo, one of the balbarid species from Riversleigh. Anna Gillespeae
http://pirforosellin.blogspot.gr/ -
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