A large prehistoric bird living in Argentina six million years ago may have soared like an eagle, but probably took off more like a clumsy albatross.
Scientists think that Argentavis magnificens, a gigantic 155 pound bird whose 23 foot wingspan rivaled that of a small plane had all the equipment necessary to get the most from downdrafts and thermals, but would have struggled to get airborne by just flapping its wings.
Instead, the bird, which is sometimes referred to as the Giant Teratorn, needed get a running start off a sloping hillside to become airborne, according to the lead researcher Professor Sankar Chatterjee, curator of paleontology at the Museum of Texas Tech University in Lubbock.
"Like an albatross or a hanglider, Argentavis needed a little sloping surface; and he needed to run a bit, and headwind would have helped. Using this trick he could take-off but after that he didn't need to do much flapping of the wings," Professor Chatterjee said.
Once in the air, Argentavis’s giant wingspan would have been perfect for getting the most out of updrafts and thermals rising up from the sloping foothills of the Andes during the late Miocene Epoch.
"Because the fossils of Argentavis are found from the foothills of the Andes to the pampas, it is likely that it used primarily slope-soaring over the windward slopes of the Andes and thermal-soaring over the open pampas,” Chatterjee added.
Professor Chatterjee and his colleagues gathered information from the creature’s fossil remains and fed them into a computer to analyze its flying capabilities. Results of the study, which appeared in the Proceedings of the National Academy of Sciences (PNAS), showed the bird’s wing structure probably didn’t have the muscle-power to lift it straight off the ground. Instead, it would have needed to launch itself either from a perch or with a running start down a sloping hillside.
"But once it was on a thermal, it could easily rise up a mile or two without any flapping of its wings - a free ride, just circling. Then at the top, the bird could simply glide to the next thermal and in this way it could certainly travel 200 miles a day,” Chatterjee said.
From such a high vantage point, and along with its huge beak and claws, Argentavis would have been a formidable predator swooping down on rodents and other unsuspecting prey.