Age of Monotremes Illustration by Peter Shouten

Platypus and echidna relatives living in Australia about 100 million years ago.

Credit: Peter Shouten

Imagine traveling back to the days of the dinosaurs, 100 million years ago. This is well before all of Australia’s marsupials – kangaroos, koalas, wombats and other furry, pouched critters – evolved. Instead, a team of palaeontologists have named it the Age of Monotremes. Monotremes are the egg-laying mammals, and there are only two types of them left in the world – echidnas and platypuses.

The Australian palaeontologists found three new species of monotremes in the opal fields of Lightning Ridge. This brings the total number of Lightning Ridge monotreme species to six. That’s more monotremes in one place than anywhere else on Earth, past or present!

One of the new fossils, dubbed an “echidnapus”, probably looked a lot like a platypus but with an echidna-like jaw. Researchers reckon that the echidnapus and the other five fossils are distant relatives of the modern echidna and platypus. The fossils provide new information about how Australia’s strangest animals came to be.

Finding a monotreme fossil is rare, but finding one that sparkles is even rarer. The other amazing thing about the Lightning Ridge fossils is that they are made of solid opal. Like the opals you find in jewellery, these fossils sparkle beautifully with changing colours. But this opal material can be useful too – the opal is translucent, so researchers can see inside the fossilised bones!

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