First ever dinosaur sitting on fossilized nest of eggs discovered

INDIANA, Pa. — It’s a find worthy of the blockbuster “Jurassic Park” and may reveal clues into how dinosaurs cared for their young. An international team has announced the discovery of the first ever fossil of a dinosaur sitting atop its nest of eggs. What makes the find unique is that the eggs still have fossilized embryos inside.

“Dinosaurs preserved on their nests are rare, and so are fossil embryos. This is the first time a non-avian dinosaur has been found, sitting on a nest of eggs that preserve embryos, in a single spectacular specimen,” explains Dr. Shundong Bi from Indiana University of Pennsylvania in a media release.

Study authors say the fossil includes an adult oviraptorosaur, a bird-like theropod dinosaur which lived during the Cretaceous Period. Researchers made the discovery in Ganzhou City in southern China’s Jiangxi Province; adding that the specimen is about 70 million years-old.

Unearthing dinosaur behavior is ‘the rarest of the rare’

Dinosaur fossil eggs
The ~70-million-year-old fossil in question: an adult oviraptorid theropod dinosaur sitting atop a nest of its eggs. Multiple eggs are clearly visible, as are the forearms, pelvis, hind limbs, and partial tail of the adult. Photo by Shundong Bi, Indiana University of Pennsylvania. (Credit:
©Shundong Bi)

Not only did researchers unearth a partial skeleton of an adult oviraptorosaur, the dinosaur was crouching in a bird-like position over a clutch of at least two dozen eggs. The team says seven of these eggs preserved the skeletons of the unhatched oviraptorids inside.

Study authors believe the eggs were very close to hatching when the oviraptorosaur died and that the dinosaur likely perished while incubating its nest, just like a modern day bird.

“This kind of discovery—in essence, fossilized behavior—is the rarest of the rare in dinosaurs,” explains Dr. Matt Lamanna from the Carnegie Museum of Natural History. “Though a few adult oviraptorids have been found on nests of their eggs before, no embryos have ever been found inside those eggs. In the new specimen, the babies were almost ready to hatch, which tells us beyond a doubt that this oviraptorid had tended its nest for quite a long time. This dinosaur was a caring parent that ultimately gave its life while nurturing its young.”

New insights into dinosaur eggs

Using oxygen isotope analyses, study authors also discovered the eggs were incubated at a high, bird-like temperature. This adds more evidence to the theory the oviraptorosaur was brooding its nest and not just guarding the eggs like modern day crocodiles do.

Dinosaur_diagram
An oviraptorid specimen consisting of an adult skeleton preserved atop an embryo-bearing egg clutch. (Credit: Indiana University of Pennsylvania)

While some of these eggs appear to be well-developed and ready to hatch, others were not as far along. Researchers believe this points to asynchronous hatching, where eggs in the same clutch hatch at different times. The study notes this trait evolved independently in oviraptorids as well as other birds alive today.

The team also made one other interesting discovery in the fossil — stones in the oviraptorosaur’s stomach. This cluster of pebbles appear to be gastroliths (or stomach stones) which the dinosaur may have intentionally swallowed to aid in digesting food.

It’s the first time paleontologists have discovered gastroliths in an oviraptorid fossil; a clue that might provide more insight into their prehistoric diet.

“It’s extraordinary to think how much biological information is captured in just this single fossil. We’re going to be learning from this specimen for many years to come,” concludes Xing Xu, paleontologist at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing.

The findings appear in the journal Science Bulletin.

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