A group of Toronto-based researchers have uncovered what is believed to be the oldest dinosaur nest found to date, pre-dating an earlier nest find by about 100 million years.
This latest find of a dinosaur nesting site is estimated to be about 190-million-years-old and was discovered in the Golden Gate Highlands National Park South Africa. This fossil find is significant because it shows family behaviors in dinosaurs and provides additional insight to the evolution of a complex dinosaur family, including reproduction behaviors.
According to CBC News, the Canadian-led team of international researchers found a nesting site of Massospondylus, a prosauropod dinosaur. A minimum of 10 nests were found at several levels of the excavation site, containing close to three dozen eggs each.
The dinosaur fossils found included the remains of the mother dinosaurs, which were all uncovered in sedimentary rocks, and dated during Early Jurassic Period.
Led by Robert Reisz, paleontologist and professor of biology at the University of Toronto's Mississauga campus, Reisz described "clutches of eggs, many with embryos," and remarkably, small imprints left by the feet of baby dinosaurs.
This find demonstrates more evidence that dinosaurs cared for their young and the babies remained with the parents until they were at least doubled in size.
Co-author David Evans of the Royal Ontario Museum said, "Even though the fossil record of dinosaurs is extensive, we actually have very little fossil information about their reproductive biology, particularly for early dinosaurs." (University of Toronto Mississauga)
Scientists note several important factors in this discovery, which include repeated use of the same nest ("nesting fidelity"), and "colonial nesting" which means the dinosaurs likely organized in groups to lay eggs. Researchers believe there could be more nests which could help enlighten modern and potentially outline more information relating to how dinosaurs cared for their young.
"The eggs, embryos, and nests come from the rocks of a nearly vertical road cut only 25 metres long," Reisz said. "Even so, we found ten nests, suggesting that there are a lot more in the cliff, still covered by tons of rock. We predict that many more nests will be eroded out in time as natural weathering processes continue."
The eggs are fragile, measuring at less than 100 microns in thickness (less than the width of human hair, reports Live Science) and researchers had to handle the find delicately in order to not cause accidental damage.
"We literally spent days and days searching for the eggs and nests, spending most of our time on our hands and knees, but once we were able to recognize what to look for, we found four nests within 10 minutes," Reisz said, reported LiveScience.
The skeletal remains of the mother dinosaurs measured approximately 20 feet (6 meters) long, and the eggs were measured to be 2.3 to 2.7 inches (6 to 7 centimeters) wide. Scientists believe, based on the type of sediments found at the site, the nests were constructed near water sources, likely due to an abundance of food for these herbivores.
"The fact that the nests are relatively close to water, and the soil was moist, suggests that there was lots of vegetation," Reisz told LiveScience.
There is currently an exhibition on display at the Royal Ontario Museum (ROM) until May 2012 entitled, "Dinosaurs Eggs and Babies: Remarkable Fossils from South Africa and features the prehistoric fossilized dinosaur eggs with embryos, along with other remarkable finds.
Digital Journal had reported on a nesting site in Nov. 2011, which was discovered in Mongolia and dated to be in the range of 70 to 80 million years ago
This most recent finding in South Africa was published yesterday in the Proceedings of the National Academy of Sciences.
Video of University of Toronto Mississauga Professor Robert Reisz and Professor David Evans at a dinosaur excavation site in Golden Gate Highlands National Park, South Africa (courtesy of University of Toronto)