A new study published in the journal Science reached the conclusion that with dinosaurs, parenting strategy involved the males’ assistance when guarding the eggs. The analysis was made on the fossilized remains of three dinosaurs found sitting on nests. Florida State University paleobiologist Greg Erickson explained that they could not find any trace of a medullary bone -- the extra bone that breeding female birds and dinosaurs use to make eggs.

"So the male tends the eggs, leaving her free to look after her own nutrition and possibly to mate with other males," explained Frankie D. Jackson, a paleontologist at Montana State University, who is also one of the authors.

This behavior has been observed on certain species of birds and there are several theories of scientists believing that birds evolved from small predatory dinosaurs about 150 million years ago.

The male contribution when it comes to parental care in less than 5 percent with mammal and reptile species. A significant difference is observed when it comes to birds, where males and females contribute to parental care together with more than 90 percent of the species.

"There are a lot of characteristics that we once thought were unique to birds that are turning out not to be -- that they first arose in their theropod ancestors," explained Montana State University paleontologist Frankie Jackson, one of the researchers, during a telephone interview.

For now, there are no explanations about what might have caused the dinosaurs to suddenly die while perching over the eggs and the investigations will continue.