Melbourne: Palaeontologists claim to have
discovered fossils of lizard-like, snail-eating, hammer-teeth
marsupials alike to the Australian pink-tongued skink lizard.
A team at the University of New South Wales has
found the fossils, dating back 10 to 17 million years ago, in
an ancient fossil field in the Riversleigh World Heritage area
in Queensland, `Proceedings of the Royal Society B` reported.
This ferret-size mammal -- now formally named
Malleodectes, meaning "hammer-biter" -- had an enormous blunt
tooth in each side of its upper jaw, according to Rick Arena,
who led the team.
"At first, the function of these teeth was a
mystery because we were unaware of any other mammal that had
hammer-teeth like this," said Dr Arena.
That was until team member Dr Scott Hocknull
of the Queensland Museum noticed the striking similarities to
a modern Australian lizard, the pink-tongued skink.
"This rainforest skink has an almost identical giant,
hammer-tooth in its dentition and in this case we know what
it`s used for -- crushing the hard shells of snails, one of
the main foods of this rainforest skink," said Dr Hocknull.
"It appears Malleodectes evolved millions of years
ago to exploit the ecological niche occupied today by these
specialised lizards," said Dr Arena.
The researchers say the similarity between the teeth
of the fossil marsupials and the living skink is a remarkable
example of evolutionary convergence.
Although from very different groups of animals,
these marsupials and this lizard have independently developed
a similar solution to the same challenge -- how to crush hard
shells to be able to swallow tasty snails.
Malleodectes eventually became extinct at some point
after 10 million years ago, when the Australian continent
began to respond to rapid climate change.
"It`s possible that species of Malleodectes may have
survived for a bit longer in rainforest communities in eastern
Australia and here found themselves in competition for snails
with the similarly-specialised ancestors of the pink-tongued
skinks," said team member Prof Mike Archer.
"If this did happen, clearly, for whatever reason,
these extraordinary mammals lost out to the lizards," he