Researchers at the University of Calgary have discovered how massive, bird-like dinosaurs sat on nests without crushing their eggs, a new study published in Biology Letters reports.
Researchers have long wondered how oviraptorosaurs — an ancient reptile species that weighed as much as a rhinoceros — managed to sit on their nests without completely smashing the eggs.
To shed light on that mystery, the team in the new study found that the extinct creatures laid their eggs in doughnut-like circles.
Though oviraptorosaurs could grow to large sizes, smaller ones did exist. Not only that, but the smaller ones did not lay their eggs in circles. In contrast, larger species created nests with big holes in the center so the dinosaurs could sit down without squashing the eggs around them.
“Oviraptorosaurs appear to have adapted to being able to sit on their clutches, even at giant body size,” said study co-author Darla Zelenitsky, an assistant professor of paleontology at the University of Calgary, told Live Science.
The strange-looking dinosaurs had parrot-like heads and toothless beaks. While they could weigh just a few pounds, certain species weighed more than few thousand.
To get a better idea of how the creatures hatched their eggs, researchers analyzed roughly 40 oviraptorosaur nests that existed from 100 million to 70 million years ago. Such analysis revealed the reptiles were particular about how their eggs were arranged.
With that information, scientists managed to measure both nest diameter and the holes in the middle of them. The team then discovered that smaller oviraptorosaurs sat either directly on their eggs or in a small hole in the center of the nest while bigger ones placed their eggs in a ring further from the center. In that way, the largest animals had little contact with their eggs as they sat down.
While that may have allowed the adults to stay in the nest and keep watch over their future young, it likely did not lead to strong temperature regulation.
Even so, the new research sheds light on a little known time process and gives more information about an ancient world.
“Dinosaur nests are particularly valuable because they give us insight into how dinosaurs evolved…adopting behaviors that allow them to warm or protect their eggs without squashing them with their behemoth bodies,” explained Lindsay Zanno, a researcher from the North Carolina Museum of Natural Sciences, according to BBC News.