COLLEGE STATION, Dec 18, 2008 – Those ferocious Hollywood meat-eating dinosaurs you're used to seeing in the movies very possibly had a much softer side: the males might even have been sort of prehistoric babysitters, according to a far-flung study conducted by a Texas A&M University researcher.
Jason Moore, a post-doctoral researcher in the Department of Geology and Geophysics, and team members from Montana State University, Florida State University and the American Museum of Natural History in New York discovered that some types of male dinosaurs probably cared for and watched over eggs in much the same way that females of other species do. Their work appears in the current issue of Science magazine.
Moore and the research team examined six nests of well-preserved dinosaur eggs, with each nest containing from 22 to 30 eggs found in Montana and Mongolia. Most of the eggs were about 75 million years old.
Numerous clues – including the size of the eggs and the internal structure of the adult bones found sitting on the eggs – indicate that males, not females, likely watched over the eggs and served in a nanny-like function as the eggs slowly developed.
"The bones we found closest to the eggs don't display characteristics of female dinosaurs," Moore says of the findings.
"Modern birds descended from dinosaurs, so we can use birds as modern representatives of dinosaurs. We have looked at some other modern-day animals for similarities as well, including crocodiles, turtles, snakes and others, and asked the question in each case, 'Which of the parents were taking care of the eggs?' Comparing these modern animals to dinosaurs, the evidence all points to the males as the ones who likely cared for the eggs."
Moore says that studies show that in birds, males participate in parental care about 90 percent of the time, but that loving parental care drastically falls to only 5 percent of mammalian species who do the egg watching.
The team examined three types of dinosaurs – Troodon, Oviraptor and Citipati. If those names don't sound familiar, just picture the types of raptors that were chasing some of the people in the lab rooms in the movie Jurassic Park, he explains. Those types were also closely related to birds.
Moore says that the lack of any "cavities" (formed by the females when laying eggs) in the bones of the dinosaurs that were sitting on the eggs is a strong indicator that males, not females, were caring for the eggs.
"It's believed the females were focused strictly on the feeding and egg laying," Moore adds. "And more and more evidence points to the male as the egg caretaker. "The findings are surprising," he notes.
"If it's true that the males were principally focused on caring for the eggs, it leads to the question of what other species might have done the same thing? It raises other important questions about the behavorial characteristics of males in other species."
Source: Texas A&M University