Dinosaur's Slow Death Captured in 'Saddest' Fossil

The slow and painful way in which a dinosaur died is revealed by the dramatic death pose of its fossilized remains.

Published on 11/10/2016 at 9:00 AM

The well-preserved remains of a new dinosaur nicknamed "Mud Dragon" likely freeze in time the death pose of the animal after its agonizing final breaths.

The new species, Tongtianlong limosus, meaning "muddy dragon on the road to heaven," was discovered lying in rock that formed from what was once hardened mud. The dinosaur, described in the journal Scientific Reports, appeared to have been trying to free itself from the mud, with its wings and neck outstretched.

Co-author Stephen Brusatte of the University of Edinburgh's School of Geosciences and his colleagues believe that the unfortunate dinosaur died in the throes of this struggle about 66–72 million years ago.

"It is one of the most beautiful, but saddest fossils I've ever seen," Brusatte told Seeker, adding that if the dinosaur had not died stuck in mud "we wouldn't have this gorgeous fossil."

The two-legged dinosaur was an oviraptorosaur, referring to a family of feathered dinosaurs known for their short, toothless heads and sharp beaks. Some, such as Mud Dragon, had crests of bone on their heads that were probably used for displays to attract mates and to intimidate rivals. Birds like today's cassowaries feature such crests.

Brusatte said that the winged, yet probably flightless, dinosaur looked like a bird.

"If you saw it alive, I bet you would have just considered it to be a weird type of fairly large bird," he explained. "It was about the size of a sheep or small donkey."

Despite the dinosaur's misfortune, it is a miracle that its skeleton was found. Construction workers at a building site in the Ganzhou region of southern China were blasting the ground with dynamite in order to make way for a high school. An explosion revealed Mud Dragon, coming close to blowing it to smithereens.

In addition to the dinosaur's revealing death pose, its fossils reveal what ecosystems were like just before the asteroid impact of 66 million years ago that killed off all of the non-bird dinos.

Mud Dragon is the sixth known oviraptorosaur from the late Cretaceous Period of this region in China. Although these dinosaurs were all related, each looked distinctive, strongly suggesting that the animals were diversifying - branching off into new species - and flourishing before the asteroid hit occurred.

Some researchers believe that dinosaurs were already in decline and that the asteroid just finished them off, but Brusatte said "that is a bunch of malarkey."

"Everything we see in the fossil record - particularly here in southern China - tells us dinosaurs were flourishing right up to the end," he continued. "There were a bunch of species living together, dominating ecosystems, and still forming new species right up to the final moments."

Not all of the dinosaurs at that time were bird-like, either. Right up until the very end there were big tyrannosaurs, long-necked plant-eating dinosaurs called sauropods, duck-billed dinos, horned plant eaters, smaller omnivores like Mud Dragon and others.

However unfortunate Mud Dragon's individual demise was, its presence, along with that of the other discovered oviraptorosaurs, suggests that southern China was home to many more dinosaurs right before the massive extinction event, said co-author Junchang Lü of the Chinese Academy of Geological Sciences' Institute of Geology.

Amy Balanoff, a research scientist from the Johns Hopkins University Center for Functional Anatomy and Evolution, has also studied dinosaurs similar to Mud Dragon.

"In recent years our knowledge of oviraptorosaur dinosaurs has increased greatly due to the amazingly preserved fossils that are coming out of this region of China, and this specimen is another example," Balanoff told Seeker. She added that these dinosaurs "are anatomically bizarre, having skull proportions that, on first glance, make it difficult to tell the front from the back."

She as well as the authors of the paper are curious about how fast dinosaurs were diverging into new species right before 66 million years ago. It could have been a rapid radiation, or a much slower turnover of species.

"Fortunately, this problem can be addressed as our knowledge of the geology of the formation increases," Balanoff said. "Geologic mapping and dating will certainly help clarify the entire story."

Image: Recreation of the dinosaur Tongtianlong limosus. Credit: Zhao Chuang