Part of the skull of an ancient rat-kangaroo. (Photo: Museum of Western Australia)

In northeastern Australia, archaeologists have discovered the teeth and bones belonging to two previously unknown species of kangaroos that went extinct about 18 million years ago. According to their analysis, published in Memoirs of Museum Victoria, these ancient kangaroos were members of the rat-kangaroo family and “are related to bettongs and potoroos,” PerthNow reports. Only, relative to these current-day species, the ancient kangaroos were pretty giant.

Let’s unpack all this. First of all, you may be wondering, what is a bettong? What is a potoroo? They almost sound like made up species, but in fact they are diminutive marsupials, about the size of rabbits, that live in Australia. Here’s a bettong:

bettong

A Rufous bettong. (Photo: Bernard Dupont/CC BY-SA 2.0)

And here’s a potoroo: 

potoroo

A long-nosed potoroo. (Photo: Peripitus/CC BY-SA 3.0)

The term “rat-kangaroo family” makes more sense now, right? The ancient teeth that the scientists found looked a lot like the teeth of modern rat-kangaroos, but the animals they belonged to would have been much larger—at least twice the size of bettongs and potoroos, or about the size of a rather large and fat cat.

Now imagine a cat-sized, rat-like thing hopping around the forest, and once again be thankful that you live on Earth in a time where the creatures we share the planet with have been scaled down quite a bit.

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