Tree-kangaroos (genus Dendrolagus) today are found only in tropical forests of Queensland and New Guinea, but between 3.5 million and 250,000 years ago, at least seven species of the extinct giant tree-kangaroo genus Bohra lived in unexpected places all over Australia.
“Bohra tree-kangaroos lived in central, southern and eastern Australia,” said Flinders University’s Professor Gavin Prideaux.
“Habitats in these areas at the time included woodland and savannah.”
“The association between living tree-kangaroos and rainforest is a recent phenomenon, and has come about only because of the extinction of giant tree-kangaroos from non-forest habitats.”
“Tree-kangaroos first evolved around 5 million years ago as forests spread during a greenhouse phase.”
“Later, as Australia dried out again, some species of Bohra adapted to more open habitats.”
Professor Prideaux and colleagues examined more than 100 teeth and bones of Bohra tree-kangaroos.
The specimens came from fossil sites extending from southern Victoria to central Australia to the New Guinea highlands.
“The tree-kangaroo story is an intriguing one,” Professor Prideaux said.
“They are a result of what is sometimes called evolutionary reversal, but not in a literal sense.”
“The earliest members of the kangaroo family descended from possum-like ancestors, and then kangaroos became specialized for hopping along the ground.”
“So, tree-kangaroos returned to where it all started for their distant ancestors many millions of years ago.”
“To do this, they needed to undo some adaptations. The characteristic body plan of kangaroos that hop on two oversized hindlegs became increasingly specialized over time.”
“Kangaroos have long feet and legs, and their ankle bones lock together to limit sideways movement. This helps ensure that hopping across the ground is energetically efficient.”
“However, flexibility and strength are advantages for climbing, so tree-kangaroos evolved…
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