Unusually colourful fossils found in Australia belong to a stunning new species of plant-eating dinosaur, scientists report today in the Journal of Vertebrate Paleontology. The remains not only belong to the first herd or family group of dinosaurs discovered in the country, they also represent the most complete dinosaur fossil yet found preserved in opal.
Discovered near the town of Lighting Ridge, about 724 kilometres northwest of Sydney, the hundred-odd bones have a rare blue-grey hue with occasional flashes of brilliant gem-quality colour. Lightning Ridge is famous for yielding fossils hewn from often brightly coloured opal, a gemstone that forms over long periods from the concentration of silica-rich solutions underground. But finding a whole new dinosaur species is remarkable.
Over a thousand dinosaur species once roamed the Earth. Learn which ones were the largest and the smallest, what dinosaurs ate and how they behaved, as well as surprising facts about their extinction.
“Any time we find a new Australian dinosaur it’s interesting, because we have so few,” says Stephen Poropat, a palaeontologist from Swinburne University of Technology in Melbourne who was not on the study team. The tally of known Australian dinosaurs is currently around 24, he notes, including Weewarrasaurus, another species from Lighting Ridge described last year.
The newest species, Fostoria dhimbangunmal, was an Iguanodon-like dinosaur that lived about a hundred million years ago during the mid-Cretaceous period, when this region was a broad floodplain with lakes and rivers flowing into the inland Eromanga Sea.
“The floodplains were frequently wet and richly vegetated, meaning they were a good place for plant-eating dinosaurs,” says study leader Phil Bell, a paleontologist at the University of New England in Armidale, New South Wales.
Studying dinosaurs from the time slice at Lightning Ridge is important, Poropat adds, as the world was then experiencing the warmest conditions of the past 150 million years.
“These dinosaurs were living in a really incredible greenhouse Earth,” he says. “The globe would have potentially looked quite different, and these fossils can tell us how these dinosaurs were coping.”
Left: This fossil toe bone belonged to a member of Fostoria dhimbangunmal. The fossils were all found in a former opal mine and show glimmers of the brilliantly coloured gemstone.
Right: This fossil is part of a vertebra from the back of a Fostoria dinosaur. Similar fossils made of opal are often cut up and lost to the jewellery trade.
PHOTOGRAPH BY ROBERT A SMITH, COURTESY OF THE AUSTRALIAN OPAL CENTRE
Bundle of bones
Long-time Lightning Ridge opal miner Bob Foster found the fossil in 1986. Scientists at Sydney’s Australian Museum, along with Australian Army reservists, helped Foster excavate the find as an accumulation of dinosaur bones embedded in blocks of rock, with the museum then taking the fossils into their collections.
But the fact they were left languishing unstudied for 15 years or so and put on display at a Sydney opal store led Foster to decide to reclaim his discovery. He returned it to Lightning Ridge, and his family eventually donated it to a local museum, the Australian Opal Centre, where Bell was able to study the find.
As a one-of-a-kind fossil assemblage, the scientists left most of the bones embedded in the rocks and instead used a CT scanner to digitally extract them for research.
“We originally thought it was one skeleton, but once we began to study the individual bones, we realised … there were parts of four scapulae, or shoulder blades, all of different sizes,” he explains.
About 60 of the bones are from a probable adult that was 16 feet in length, while the others are from juveniles of various sizes, prompting Bell to speculate that they were the remains of either a family or small herd of herbivorous dinosaurs.
“We have bones from all parts of the body, but not a complete skeleton,” he says. “These include bones from the ribs, arms, skull, back, tail, hips, and legs. So, it’s one of the most completely known dinosaurs in Australia … [with] 15 to 20 percent of the skeleton of the species.”
The name Fostoria honours Bob Foster, while the species name dhimbangunmal means ‘sheep yard’ in the local Yuwaalaraay and Yuwaalayaay Aboriginal languages. It was chosen by Foster’s wife Jenny, who is Gamilaraay Aboriginal, to honour the Sheepyard locality where Foster’s now defunct mine once operated.
About the length of an elephant, Fostoria would have habitually walked on its hind limbs, though the scientists surmise it sometimes used all four to get around. It likely ate primitive plants called horsetails as well as bunya and hoop pines, fossils of which are also found in the region. (Find out about a sauropod dinosaur that likely crawled as a baby and walked on two legs as an adult.)
A relative of Iguanodon and Australia’s most famous dinosaur, Muttaburrasaurus, Fostoria is also an early member of a group that would elsewhere evolve into the duckbilled hadrosaurs, which were common in North America and Asia toward the end of the time of the dinosaurs, roughly 66 million years ago.
“Early duckbill dinosaurs were the primordial soup from which the fantastical crested species … later evolved,” says Lindsay Zanno, a palaeontologist at the North Carolina Museum of Natural Science in Raleigh who was not involved in the research.
“Although the pace of discovery of early duckbills like Fostoria has intensified around the globe, we still have much to learn about how these herbivores became so successful,” she adds.
“Piecing together that story is essential for understanding dinosaur ecosystems, especially across southern continents, and Fostoria brings us one step closer to sorting it out.”
Lead Image: A herd of Fostoria dinosaurs walks along a lakeshore near what is now Lightning Ridge, Australia, in an illustration.
ILLUSTRATION BY JAMES KUETHER
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