January 24, 2012
Paleontologists Uncover World’s Oldest Dinosaur Nesting Site
An international team of researchers say that they have unearthed a 190-million-year-old dinosaur nesting site that they are calling the oldest such location in the world.
In fact, according to a January 23 press release announcing the discovery, lead author and University of Toronto Mississauga biology professor Robert Reisz and colleagues claim that the newly discovered excavation site, which is located at the Golden Gate Highlands National Park in South Africa, pre-dates the oldest previously known nesting sites by 100 million years.
Reisz, along with co-author David Evans and a team of experts, reportedly discovered at least 10 nests at various different levels at the South African site. Those sites were each home to as many as 34 round eggs, and according to the press release, they found "clutches of eggs, many with embryos, as well as tiny dinosaur footprints, providing the oldest known evidence that the hatchlings remained at the nesting site long enough to at least double in size."
Furthermore, the way that the nests were distributed throughout the sediment shows that the dinosaurs which used them exhibited a behavior Reisz and colleagues identify as "nesting fidelity," meaning that they used the nesting ground on multiple occasions. Specifically, they would gather together in groups to lay their eggs -- a trait known as "colonial nesting" which had never before been discovered at this point in the fossil record.
“The eggs, embryos, and nests come from the rocks of a nearly vertical road cut only 25 meters long,” Reisz said in a statement on Monday. “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 nesting area was described by the paleontologists as "highly organized," which they say leads them to believe that the mother -- who was at least six meters long -- could have carefully arranged them in a certain way after laying the eggs. Those eggs were only about six to seven centimeters in diameter.
“Even though the fossil record of dinosaurs is extensive, we actually have very little fossil information about their reproductive biology, particularly for early dinosaurs,” said Evans, the associate curator of Vertebrate Paleontology at the Royal Ontario Museum.
“This amazing series of 190 million year old nests gives us the first detailed look at dinosaur reproduction early in their evolutionary history, and documents the antiquity of nesting strategies that are only known much later in the dinosaur record,” he added.
Joining Reisz and Evans as co-authors on the study were Dr. Hans-Dieter Sues of the Smithsonian Institute, Dr. Eric Roberts of Australia's James Cook University, and Dr. Adam Yates of the University of the Witwatersrand in South Africa. Their research appears in the journal Proceedings of the National Academy of Sciences.
Image 1: This is an artist's interpretation, showing 190 million year old nests, eggs, hatchlings and adults of the prosauropod dinosaur Massospondylus in Golden Gate Highlands National Park, South Africa. Credit: Artwork by Julius Csotonyi
Image 2: This is a close-up of embryonic skeleton of Massospondylus from clutch of eggs at the nesting site. The head was pushed out of the egg after death, probably because of gases produced by decay. Credit: Photo by D. Scott
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