ARCHEOLOGISTS have discovered three new species of ancient giant kangaroo.
The fossils were found in Australia and New Guinea, and they suggest the species was much more diverse than previously thought.
The three newly discovered species belong to a now-extinct group called Protemnodon.
These creatures lived around 5 million to 40,000 years ago.
The largest was about double the size of the modern kangaroos.
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Lead researcher Dr. Isaac Kerr and a team focussed on three fossils for the study.
The complete fossils were found in 2013, 2018, and 2019 and all belong to the genus Protemnodon.
A new study about the fossils has been published in the journal Megataxa.
The biggest ancient kangaroo mentioned in the study is called Protemnodon viator.
It was much bigger and weighed up to 375 pounds, twice as much as a male red kangaroo.
The species would have been squatter and more muscular than modern kangaroos.
Two other species mentioned in the study are called Protemnodon mamkurra and Protemnodon dawsonae.
"We photographed and 3D-scanned over 800 specimens collected from all over Australia and New Guinea, taking measurements, comparing and describing them. It was quite the undertaking.
"It feels so good to finally have it out in the world, after five years of research, 261 pages and more than 100,000 words.
"I really hope that it helps more studies of Protemnodon happen, so we can find out more of what these kangaroos were doing.
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"Living kangaroos are already such remarkable animals, so it's amazing to think what these peculiar giant kangaroos could have been getting up to," said Dr Kerr.
"It's great to have some clarity on the identities of the species of Protemnodon," co-author Professor Gavin Prideaux said.
"The fossils of this genus are widespread and they're found regularly, but more often than not you have no way of being certain which species you're looking at.
"This study may help researchers feel more confident when working with Protemnodon."