Unearthing a beautiful opal is usually a reward in itself. Discovering that your gemstone is actually an opalized fossil of a millions-year-old, previously unknown dinosaur, well that's priceless.

Imagine the joy that opal buyer, Mike Poben, must have felt upon finding such a precious item, which was recently dug up near the small country town of Lightning Ridge, in Australia, reports National Geographic.

The creature immortalized in the stone has been named Weewarrasaurus pobeni, after the Wee Warra opal field near Lightning Ridge where it was found. It was a fairly diminutive animal by dinosaur standards — about the size of a dog — and paleontologists say it lived about 100 million years ago, in the Cretaceous. Based on the size of its jaw and teeth, which were the parts fossilized in the opal, it was likely a bipedal grazing herbivore, similar to an Iguanodon.

'My jaw dropped'

"I remember Mike showing me the specimen and my jaw dropped. I had to try hard to contain my excitement, it was so beautiful," said Phil Bell of the University of New England in Armidale, New South Wales, lead author on the study describing the fossil.

Weewarrasaurus adds to a relatively small list of dinosaurs known to have called the eastern part of the southern supercontinent of Gondwana home. Fewer than 20 Australian dinosaurs have been named, which makes this rainbow-glistened fossil even more precious.

Though the area where the fossil was found is largely desert today, back in the Cretaceous it would have been a lush, green space on the edge of a giant inland sea. The dinosaurs that called this Eden-like landscape home were significantly distinct from the herbaceous behemoths that would have been stomping around in North America, creatures that included Triceratops and Alamosaurus.

The fossil helps to flesh out exactly what the ecosystem was like in this lesser-known environment of the Cretaceous.

"The new discoveries can help us understand the connections, possible migrations, and the relationship of the small bipedal herbivorous dinosaurs of South America, Antarctica, and Australia during the Cretaceous," explained Penélope Cruzado-Caballero, an expert on herbivorous dinosaurs at the National University of Río Negro in Argentina.

Gemstone turns out to be fossil of an unknown dinosaur
Miners in Australia uncover the opal-filled fossil of a dog-size herbivore named Weewarrasaurus pobeni.