Between 120 and 130 million years ago, in the age of dinosaurs, northeastern China had vibrant temperate forests and lakes that nourished diverse ecosystems. Fossils from this period remained untouched for millions of years until villagers in the 1980s began unearthing exceptionally well-preserved specimens.
These finds, often sold to collectors and museums, set off a fossil craze that has since turned the site into one of the most actively excavated paleontological sites in the world, visible even from space.
Well-preserved dinosaur fossils
Dinosaur fossils found in the Yixian Formation were very well preserved. Unlike the usual fragmentary skeletal remains found elsewhere, these fossils often contained soft tissue, internal organs, feathers, fur, and even stomach contents.
Notable among these finds is a cat-sized mammal fighting a small dinosaur, seemingly frozen in time. Such discoveries confirmed that modern birds are descendants of feathered dinosaurs and provided important insights into their evolution, changing paleontological understanding.
Early theories suggested that a sudden volcanic event similar to the eruption of Mount Vesuvius that buried Pompeii may have been responsible for the preservation of these fossils, leading to the formation being dubbed “China’s Pompeii.”
Debunking volcanic theories
A recently published study Proceedings of the National Academy of Sciences, This casts doubt on the long-held belief that volcanic activity is the main reason why these fossils have been preserved intact. Using precise dating methods, researchers argue that the fossils were preserved not as a result of dramatic volcanic catastrophes, but rather as a result of more mundane events such as nest collapses and periods of heavy rain that quickly buried remains.
This new study places the age of these fossils at less than 93,000 years, rejecting the idea that the preservation was the result of multiple volcanic impacts over millions of years.
Well-preserved dinosaur finds
“These are probably the most important dinosaur discoveries in the last 120 years,” said study co-author Paul Olsen, a paleontologist at Columbia Climate School’s Lamont-Dougherty Earth Observatory.
“But what is said about conservation methods highlights an important human bias. That is, attributing extraordinary causes, that is, miracles, to ordinary events whose origins we do not understand. These [скам’янілості] – a snapshot of daily deaths that occur over a relatively short period of time under normal conditions.”
Evidence against volcanic theories
The research team ruled out the possibility of preservation of volcanic lahars (fast-moving mudflows) due to their violent nature that could destroy fragile remains.
The theory of pyroclastic flows similar to those that buried Pompeii has also been rejected. Such currents can burn feathers and fur, and bodies may remain in the characteristic “fist” position seen in victims of extreme heat. In contrast, the animals in the Yixian Formation are in more relaxed poses, indicating a peaceful ending.
Theory of sudden collapse of the hole
The researchers suggest that most of the preserved fossils are the result of sudden collapse of the nest rather than volcanic disasters. This theory was confirmed by the composition of the rock surrounding the fossils. While normal rock formations consist of coarse grains, the material immediately around and inside the skeletons was finer; This suggests that bacteria or insects have broken down the soft tissue, protecting the bones and allowing the fine sediment to seep in.
Even today, nest collapse can be fatal for animals like penguins, Olsen said, showing how the process played a role in preserving ancient creatures. The extraordinary discovery of a dinosaur at war with a mammal could potentially be explained by such collapses. Perhaps the mammal invaded the dinosaur’s nest in search of food or safety when both met their end.
What caused the hole to collapse?
Although researchers believe the primary cause of death was nest collapse, the exact triggers remain speculative. One possibility is that larger dinosaurs, which are not recorded in the fossil record but probably roamed the area, accidentally crushed the nests as they moved through the landscape. Additionally, periods of heavy rainfall can disrupt the soil’s balance and contribute to subsidence.
Potential for future dinosaur discoveries
Olsen believes that the unique preservation of the Yixian Formation is not exceptional, and that equally well-preserved dinosaur fossils could be uncovered in other parts of the world if excavated with the same intensity.
“There is no other place in this environment where such intense harvesting takes place,” he said.
Although China has taken steps to regulate fossil sales, demand remains high and significant investments are being made to develop tourism around these fossil fields. Olsen mentioned areas in the eastern United States that have ecological similarities to Isian, such as a quarry on the border of North Carolina and Virginia, areas in Connecticut and a former quarry in New Jersey. However, due to the high cost and value of the land, large-scale excavations have not yet been carried out in these areas.
“It takes a lot of effort and it’s expensive. And the land in these areas is valuable. That’s why no one is doing it. At least for now,” Olsen concluded.
Source: Port Altele
