Carnegie Museum scientists researching unique dinosaur
Some 70 million years ago on an ancient desert plain in what is now southern China, a feathered flightless dinosaur about the size of a small black bear crouched over a nest containing a brood of at least 24 eggs.
Some of the fertilized embryos were soon to hatch. Others were less developed, but they and the adult were abruptly smothered, probably in a muddy flash flood. The adult died with its arms hugging the nest, protecting the eggs with its body.
The position of the fossilized dinosaur over eggs containing its fetal babies provides the first behavioral evidence showing this type of preavian animal was a dedicated, caring parent that ultimately gave its life while protecting and nurturing its young.
The full version of a scientific paper describing the find, published last week in the journal Scientific Bulletin, was co-written by researchers including staff of
Pittsburgh’s Carnegie Museum of Natural History.
“This fossil is quite remarkable,” said Matt Lamanna, the Carnegie’s co-interim director and lead dinosaur paleontologist. “Because some of the eggs are so near to hatching, we know the dinosaur didn’t die while in the act of laying them. And because it’s right on the eggs we know it wasn’t just guarding them. It spent considerable time incubating and nurturing its offspring. We haven’t seen this before.”
The fossil, discovered about a decade ago within metropolitan Ganzhou City in Jiangxi Province, is what remains of an oviraptorosaur, a classification of birdlike dinosaurs with similar hips, hollow bones and three toes on each of two feet. Oviraptorosaurs thrived during the Cretaceous Period, the third and final juncture of the Mesozoic “Age of Dinosaurs” that extended from 145 million to 66 million years ago.
About 10 years after the dig, paleontologist Xing Xu, of a Beijing scientific institute, requested the research assistance of Shundong Bi, a professor at Indiana University of Pennsylvania and research associate at Carnegie Museum of Natural History. He and Mr. Lamanna collaborated with Mr. Xing in writing the peer review report. Carnegie scientific artist Andrew McAfee produced illustrations for the paper.
The fossil includes an incomplete skeleton of a large, presumably adult oviraptorid. Mr. Lamanna said the nurturing parent was probably not the mother.
“There are some indications it was the dad,” he said. “There is a type of tissue deposited in the bones of modern female birds that is only present when she lays eggs and shortly after. Evidence of that tissue has not been found in this fossil. There are modern examples. Ostrich males sit on their eggs.”
Another unusual aspect of the oviraptorid specimen is the cluster of gastroliths, or stomach stones, found in the adult’s abdominal region. Modern birds, particularly those that eat grains and other plant matter, deliberately swallow small stones and pebbles to grind food within the gizzard. Mr. Lamanna said this is the first time confirmed gastroliths have been found inside an oviraptorid. Presence of the stones may provide new insights into the diets of these ancient animals.
Curiously, research on the fossilized eggs identified an oxygen isotope ratio that indicates some level of warmth.
“It’s a relatively high temperature like we would find in brooding eggs,” said Mr. Lamanna. “That suggests this creature was warmblooded and was incubating its eggs. There’s still some discussion about that, but if it is true, it would finally lay to rest some theories about oviraptorosaurs.”
The unique archaeological tableau is curated in a Chinese museum. Mr. Lamanna said discussions are underway about importing a reproduction to be displayed at the Carnegie Museum of Natural History.