The Miracles in the Mundane

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The Yixian Formation in northeast China has long been hailed as one of the richest fossil beds in the world, preserving stunningly detailed remains of dinosaurs, mammals and birds from 120 to 130 million years ago.

Known for its “frozen-in-time” specimens – some of the remains even have their feathers and internal organs intact – the site has often been compared to the ancient Roman city of Pompeii, which was buried by the eruption of Mount Vesuvius in 79 CE. The volcanic blast encased residents in ash, preserving them in lifelike poses for nearly two millennia.

Many researchers believed a similar volcanic catastrophe was responsible for Yixian’s remarkable fossils. But a new study suggests a far less dramatic story.

Paleontologist Paul Olsen and his team believed that the fossils were preserved through more mundane processes, such as burrow collapses and sediment buildup during rainy periods.

“But what was said about their method of preservation highlights an important human bias – that is, to ascribe extraordinary causes, i.e. miracles, to ordinary events when we don’t understand their origins,” said Olsen, a co-author of the paper.

Unlike Pompeii, where victims’ bodies were contorted from heat and asphyxiation, many Yixian fossils appear to be peacefully “sleeping.”

This discrepancy led Olsen’s team to analyze sediment surrounding two Psittacosaurus fossils. They discovered fine-grained sediment inside the fossils, suggesting they were buried intact with their flesh still shielding the bones – a process not possible with violent volcanic flows.

Using advanced dating techniques, the researchers pinpointed the fossils to a compact 93,000-year period, a time marked by wet climate cycles that caused rapid sedimentation in lakes and on land.

“These (fossils) are just a snapshot of everyday deaths in normal conditions over a relatively brief time,” Olsen explained.

Meanwhile, some paleontologists remain skeptical of the findings.

“Sometimes you find fossils in normal sediment like they found,” Baoyu Jiang from Nanjing University, who was not involved with the study, told NPR. “But most of the time, the feathered dinosaurs, they were preserved (by) volcanic ashes.”