PARIS – A treasure trove of fossilized dinosaurs and other long-extinct species in northeastern China was created, Pompeii-style, by an erupting volcano, a study recently published in the journal Nature Communications says.
A seam of rock known as the Yixian and Jiufotang formations, in western Liaoning province, is the burial ground for an astonishing array of creatures that lived around 120 million years ago in the Early Cretaceous period. Called the Jehol Biota, it is the richest and widest source of fossils ever found.
It has yielded the remains of dinosaurs, pterosaurs, early birds and mammals, as well as turtles, lizards, freshwater fish, frogs, plants and insects, which inhabited a long-gone vista of lakes and conifer forests.
Many of the specimens are astonishingly well preserved, revealing even scales, feathers, hair or skin — precious finds for paleontologists.
The secret of the preservation, according to the study published Tuesday and led by Baoyu Jiang of Nanjing University in Jiangsu, lies in a brutal volcanic episode that extinguished life all around and then buried it in dust, locking it away for eternity.
Jiang’s team looked closely at 14 bird and dinosaur fossils and the thin layer of darkish sediment in which they were found, at five locations.
The big killer, they believe, was pyroclastic flow — a vicious outpouring of hot, suffocating gas and superfine dust, moving at gale-force speed.
Under the microscope, debris from plants showed blackened carbon streaks, and in the fossilized skeletons, hollow bones were filled with fine quartz grains.
But the biggest indicator of all came from crisscrossed cracks at the bone edges that were caused by heat stress. This phenomenon was also found in the bones of the victims at Pompeii, the Roman town that was buried by an eruption of Vesuvius in 79, the authors said.
Previous researchers had noted that the Jehol Biota sediment was volcanic. They surmised there had been a mass die-out because so many different species — terrestrial, aquatic and avian — were all clustered in one area.
But suspicions that an eruption was to blame for the die-out had lacked hard evidence until now.