When Mount Vesuvius erupted in 79 CE the ash quickly covered the city of Pompeii and other nearby villages in over 4 meters (13 feet) of ash. The damage was so extensive the site was lost for nearly 1500 years. Because of the dry conditions caused by the ash and pumice, archeologists discovered that Pompeii was actually preserved remarkably well. A similar eruption is credited with giving China part of their extensive collection of beautifully-preserved dinosaur fossils.  The study comes from Baoyu Jiang from Nanjing University and was published in the journal Nature Communications.

China is home to many beautiful early fossils, but one particular area in the Liaoning province has a fossil site of Early Cretaceous specimens that are incredibly well preserved, thanks to a volcano. The site, called Jehol Biota, is jam-packed with diversity. There are dinosaurs, mammals, fish, insects, plants, and much more with many impressions from skin, hair, and feathers still in tact. 

Geologic sampling from Jehol Biota revealed a layer of incredibly dark sediment, consistent with what would have appeared following a volcanic eruption. It appears that the incredibly fine ash rapidly descended on the area along with lethal hot gas, killing all of the animals in its path, just like what happened in Pompeii. If the heat was not enough to kill them, the complete lack of breathable air did. As the dust settled, it sealed in the organisms and protected it from the elements; the ideal environment for fossilization. 

Fourteen specimens from five different locations were selected for closer inspection. Under the microscope, Jiang et al. were able to find char marks on plants. Bones showed obvious trauma caused by extensive heat and bird bones that are typically hollow were packed with mineral dust, also indicating exposure to volcanic activity. The dust didn’t just affect the organisms on land, but the ash actually mixed into lake water, preserving the marine life as well. 

Because of the rich diversity present in the Jehol Biota fossil site, it had been predicted that a localized event caused so many animals die in a very short amount of time. It had been hypothesized that volcanic activity could have played a part in it, but there had not been any direct evidence of such an event until these results.