Wednesday, June 30, 2010

Sauropods and Megapodes

Rabaul and the vulcano Tavurvur
Megapode eggs in volcanically heated sand on Papua New Guinea. Photo by Rita Willaert, via flickr.

Sometimes, an idea is too good not to be repeated. Some members of the family of modern birds called megapodes have found volcanically heated ground quite suitable for incubating their eggs. It turns out that at least some sauropods had the same idea.

Reporting their findings in Nature, paleontologists Gerald Grellet-Tinner and Lucas E. Fiorelli have determined that an unidentified species of large sauropod established a nesting ground in a geothermal area in Cretaceous Argentina. The geological signature is unmistakeable, bearing minerals that are known to occur at modern geothermal areas, as well as the remains of stromatolites, the algal mats that produce the fantastic array of colors that draw crowds of tourists to hot springs and geysers. Grellet-Tinner and Fiorelli note that this area seems to have been the Cretaceous equivalent of Yellowstone's Norris Geyer Basin, home of the Steamboat Geyser. The moisture of the soil and its temperature of about 80 °C would have created ideal conditions for the eggs to incubate. All egg clutches were found within three meters of geyser vents.

This discovery sheds important light on the nesting habits of sauropods and further fleshes out the relationships between dinosaurs and their environments that allow us to reconstruct Mesozoic ecology. Grellet-Tinner and Fiorelli suggest that next, paleontologists should examine other known nesting sites to determine if geothermal activity was a major factor in where sauropods chose to lay their eggs.

More on sauropods: Archosaur Musings features a guest post from Peter Falkingham discussing his new research which provides a nice explanation for why many sauropod trackways only provide prints from the forelimbs.

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