Did the world’s best-preserved dinosaurs really die in ‘Pompeii-type’ events?

By the 1990s, it was clear that the so-called Yixian Formation contained uniquely well-preserved remains of dinosaurs, birds, mammals, insects, frogs, turtles and other creatures. Unlike the skeletal and often fragmentary fossils unearthed in most other places, many animals came complete with internal organs, feathers, scales, fur and stomach contents. It suggested some kind of sudden, unusual preservation process at work.

The leading hypothesis for the perfect fossils up to now has been sudden burial by volcanism, perhaps like the waves of hot ash from Mt. Vesuvius that entombed many citizens of Pompeii in A.D. 79. The Yixian deposits have been popularly dubbed the “Chinese Pompeii”. Though the Pompeii idea is highly appealing, a study says it is totally wrong. Instead, the study says the creatures were preserved by more mundane events including collapses of burrows and rainy periods that built up sediments that buried the dead in oxygen-free pockets. The current study used newly sophisticated technology to date the fossils to a compact period of less than 93,000 years when nothing particular happened.