A new report by Jiang Baoyu at Nanjing University argues that a volcanic eruption was responsible for a collection of pristinely preserved dinosaur fossils in Liaoning province.
The ancient Roman city of Pompeii was wiped off the face of the earth when nearby Mount Vesuvius erupted in 79 CE. The eruption covered the entire city and nearby villages in over four metres (13 feet) of ash. Pompeii was rediscovered in the late 16th century, remarkably well preserved due to the dry conditions created by the ash and pumice.
A similar scenario is now being suggested for a remarkable fossil site in Liaoning province, Jehol Biota. The site is packed with diverse, incredibly well preserved specimens from the Early Cretaceous; including mammals, fish, dinosaurs, insects and plants with many still having impressions from skin, hair and feathers fully intact. Thank you, volcano.
Geologic sampling from the site revealed a thick layer of very dark sediment, consistent with volcanic residue. The incredibly fine ash descended rapidly on the area, accompanied by a lethal, hot gas. Anything alive in the area was killed and encased in ash, preserving it for future generations to discover.
Fourteen of the Jehol Biota specimens, from five different locations, were put under the microscope for closer inspection. Jiang and his colleagues found char marks on plants, bones with obvious trauma caused by extreme heat, and bird bones packed with mineral dust. (Bird bones are usually hollow, a characteristic which aids in flight.)
The dust didn’t just affect the terrestrial organisms either, the ash mixed with lake water, preserving aquatic life as well.
Because of the rich diversity in the Jehol Biota fossil site, it had previously been theorised that a localized single event the cause of the mass die-off. Scientists hypothesized that volcanic activity could be an explanation, at least in part, but there had been no direct evidence of such an event until Jiang et al. provided it.
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