Archaeologists have discovered thousands of fossils which they believe were preserved by a pyroclastic volcanic avalanche in northeastern China.

The fossil bed has the remains of birds, dinosaurs, mammals, lizards, and plants from 120 to 130 million years ago in the Early Cretaceous period, according to USA Today.

The study was run by Baoyu Jiang of Nanjing University and was published in Nature Communications.

Click here to read the full published paper.

The fossil collection, which has been called Jehol Biota, were found in an area that stretches 180 miles long and 60 miles wide, according to USA Today.

A number of the fossils still contain features like stomach contents, hair, feathers, and skin, which should provide researchers a chance to learn more about that time period.

The hot ash likely made a mold around the creatures, thus preserving their bodies, though many of them had bent limbs, which archaeologists believe is a sign of a pyroclastic volcanic avalanche.

"All the evidence supports this hypothesis," said study co-author Jin Meng, who is a paleontologist at the American Museum of Natural History in New York, according to USA Today. "Many or most of the vertebrate fossils were preserved this way."

Patrick Orr, who works at the University College Dublin, has been quoted saying he is "intrigued" by how the fossils were able to stay together, but feels we shouldn't be quick to assume that's how it occurred.

"I'm not saying the authors are incorrect, but there are other plausible mechanisms that have been reported elsewhere," said Orr, who is a geologist at the university, according to USA Today. "Like all good, provocative papers, this challenges existing ideas and sets up a whole new set of questions."

See Now: OnePlus 6: How Different Will It Be From OnePlus 5?