The holotype skull of Ganguroo robustiter.
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From Cooke et al., 2015.
The holotype skull of Ganguroo robustiter.

Paleo Profile: Ganguroo robustiter

Name: Ganguroo robustiter

Meaning: The species name denotes that this animal was about 20% larger than other known species of Ganguroo.

Age: Around 13 million years old.

Where in the world?: The Riversleigh World Heritage Area, Australia.

What sort of critter?: A prehistoric kangaroo.

Size: Relatively small for a kangaroo, around the size of today’s tammar wallaby.

How much of the creature’s body is known?: The holotype – the specimen used to establish the name – includes a complete skull, lower jaws, 17 vertebrae, 26 ribs, 24 tarsal bones, the shoulderblades, and elements of both arms. Paleontologists have also uncovered multiple other skulls and skeletal elements that can be assigned to this species at various sites.

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Additional skulls of Ganguroo. From Cooke et al., 2015.

Claim to fame:
Of all the fossil sites in the world, Australia’s Riversleigh World Heritage Area has to rank as one of the most spectacular. Many of the fossils found here, ranging between 33 and 5 million years old in age, are delicately preserved in soft limestone that can be etched away with weak acid. And among the scientific treasures to tumble out of the stone is a new species of fossil kangaroo.

Queensland Museum paleontologist Bernard Cooke and colleagues have named the species Ganguroo robustiter. This is the third species named in the genus, and, thanks to a great collection of skulls and postcrania, is now the best known of the three. It’s also the biggest. While these were still relatively small hoppers – about the size of small wallabies – Ganguroo robustiter was more robust than the species that preceded it. This might indicate, Cooke and coauthors write, that the newly-named species was part of a trend towards increasing body size in response to changing habitats during the Miocene. Exactly what those changes were, however, are still held secret in the rock record.


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