(Web Desk) - A groundbreaking study has challenged the long-held belief that China's remarkably preserved dinosaur fossils were created by volcanic events similar to those at Pompeii.
The Yixian Formation in northeast China's Liaoning Province, dating back 120 to 130 million years, has been a treasure trove of perfectly preserved fossils for over two decades.
These extraordinary finds include hundreds of feathered dinosaur skeletons, along with insects, plants, shells and fish.
Researchers have now discovered that these fossils formed during a brief 93,000-year period without any volcanic activity, overturning previous theories about their preservation.
For decades, scientists believed these fossils were preserved by sudden volcanic events, much like the victims of Mount Vesuvius at Pompeii.
Previous studies suggested multiple volcanic events occurred over a million years, with lahars - fast-moving mud slurries - or pyroclastic flows repeatedly burying and preserving creatures.
However, researchers now argue that lahars would have been too violent to preserve intact skeletons.
Unlike Pompeii's victims, who were found in contorted 'pugilistic' positions due to extreme heat, the Chinese fossils show no signs of burning or heat damage.
Many specimens were found with feathers and fur intact, which would have been destroyed by volcanic activity. Instead, researchers found evidence pointing to sudden burrow collapses as the primary cause of preservation.
Rock cores surrounding the fossils revealed coarse grains, whilst finer grains were found immediately around and within the skeletons.
This pattern suggests the animals experienced gradual decay, allowing fine grains to seep in and fill the voids whilst bones remained intact.
Many specimens were discovered in sleeping positions, with arms and tails tucked cosily around their bodies.
Heavy rainfall during this period likely destabilised the ground, causing burrows to collapse and entomb their inhabitants.
This theory also explains a remarkable fossil showing an early mammal and small dinosaur locked in combat, possibly preserved when a burrow collapsed during an invasion attempt.
The findings challenge how we view extraordinary fossil preservation, according to study coauthor Paul Olsen from Columbia Climate School's Lamont-Doherty Earth Observatory.