It's hot storage. Millions of years before volcanic ash entombed the Roman town of Pompeii, a group of dinosaurs succumbed to a similar fate. China's famous feathered dinosaur fossils owe their exquisite preservation to volcanic eruptions between about 130 and 120 million years ago.
The Jehol fossils have transformed our understanding of dinosaurs by showing that the relatives of Velociraptor and T. rex had a feather-like body covering, like birds. The Jehol deposits also preserved soft tissue from early mammals and flowering plants.
Baoyu Jiang of Nanjing University, China, and his colleagues think they know why the remains are so well preserved. They found carbon layers on the bones with a structure and composition that suggests they are charred soft tissue – and the limbs of skeletons are flexed as if they had been trapped in volcanic ash.
Raymond Rogers at Macalester College in St Paul, Minnesota, thinks the work may help explain the unusually good preservation seen in the region. "Examples of extraordinary preservation in the fossil record, such as the Jehol biota, generally demand extraordinary explanations," he says – and a Pompeii-like volcanic eruption fits the bill. But more work is needed to fully test the idea, he cautions.
The authors make a strong case, says David Eberth of the Royal Tyrrell Museum in Drumheller, Alberta, Canada. But he points out they only looked at 14 animal fossils. "Their sample size is just too small," he says. Other factors were probably involved in preserving Jehol fossils elsewhere in the area, he says.
Journal reference: Nature Communications, DOI: 10.1038/ncomms4151
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