Herd of Opal-encrusted Dinosaurs Discovered in Australian Outback

A herd of opal-encrusted dinosaurs representing an entirely new species has been discovered in Australia.

The fossils were first unearthed in an opal mine in New South Wales back in the 1980s. After being donated to a museum, they were left unexamined for three decades.

"There are about 60 opalized bones from one adult dinosaur, including part of the braincase, and bones from at least another three animals," Phil Bell, from the University of New England, Australia, said in a statement.

The new species has been named Fostoria dhimbangunmal. It dates to the mid-cretaceous period (around 100 million years ago) and is a two-legged type of iguanodontian—a clade of herbivorous dinosaurs that first emerged around 175 million years ago. Findings are published in the Journal of Vertebrate Paleontology.

F. dhimbangunmal represents the most complete opalized dinosaur in the world. Opalized fossils are formed in a similar way to other fossils—but instead of being preserved in rock, they are preserved in silica. "Opal forms in cavities within rocks. If the cavity is there because part of a living thing—for example a bone, shell or pinecone—was buried in the sand or clay before it turned to stone, then the opal can form a fossil replica of the object that was buried," the Australian Opal Center, which housed the fossils, explains on its website.

Fostoria dhimbangunmal
Artist impression of Fostoria dhimbangunmal. James Kuether

"Fostoria has given us the most complete opalized dinosaur skeleton in the world. Partial skeletons of extinct swimming reptiles have been found at other Australian opal fields, but for opalized dinosaurs we generally have only a single bone or tooth or, in rare instances, a few bones. To recover dozens of bones from the one skeleton is a first," Jenni Brammall, a paleontologist with the Australian Opal Centre, said in a statement.

Initially, researchers thought the fossils belonged to just a single individual. "But when I started looking at some of the bones, I realized that we had four scapulae [shoulder blades] all from different-sized animals," Bell said.

Fostoria dhimbangunmal
Opal-encrusted Fostoria dhimbangunmal toe bone. Robert A. Smith, courtesy Australian Opal Centre

The team eventually identified four Fostoria skeletons, including juveniles and adults. This indicates they were part of a herd—the first time such a discovery has been made in Australia.

F. dhimbangunmal is closely related to the species Muttaburrasaurus, which was discovered in Queensland in 1980.

At the time F. dhimbangunmal would have walked the Earth, Australia was still connected to Antarctica as part of the remains of the supercontinent Gondwana, which began breaking up around 180 million years ago. The discovery of a new species adds to Australia's dinosaur record. As the researchers note, "Australia's dinosaur fossil record remains one of the most poorly understood of any continent."

Commenting on the latest discoveries, Ralph Molnar, a paleontologist at Museum of Northern Arizona in Flagstaff, told Smithsonian Magazine: "Australian dinosaurs are globally important, and as more discoveries are made, they will play an increasingly significant role in our understanding of that time."