Chatham professor's theory takes flight
The pterosaur was a flying reptile as tall as a giraffe and with a 34-foot wingspan that existed 100 million to 65 million years ago.
Dr. Michael Habib
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Michael Habib was pleased when Discover Magazine informed him that his explanation of how a giant prehistoric reptile launched itself into flight had been ranked among the top 100 science stories of 2009.
It was No. 76 on the Discover list, to be exact.
His research details how pterosaurs, which were as tall as a giraffe with wingspans reaching 34 feet, hoisted their 500 pounds into the air before wing flapping would begin, eventually able to reach 40 mph speeds over long distances.
Dr. Habib's research, published one year ago in the journal Zitteliana, edged out such topics as asteroids leading to life on Earth, the discovery of an Alzheimer gene and description of how Earth got its oxygen supply, among others. And it fell just behind research proving that people can smell fear.
The notable ranking merits some academic wing-flapping.
"No. 76 is not half bad," said Dr. Habib, a biologist who joined Chatham University faculty last fall. "It is a good media hit for me, the school, the students and the subject."
Dr. Habib, 29, who received undergraduate and graduate degrees from the University of Virginia and a doctoral degree from Johns Hopkins University, achieved the ranking by solving the long-standing mystery of how pterosaurs achieved liftoff.
Scientists long had speculated that an animal as tall as a giraffe would need to build up significant speed and momentum before takeoff, requiring an airport-sized runway. "For a jumbo-jet type animal the same thing applies," Dr. Habib said. "How did it get off the runway?"
Yet others argued that the prehistoric flying reptile took flight by running downhill or jumping off hills or cliffs.
With his own research, Dr. Habib flew off in a whole new direction.
He concluded that the pterosaur had stronger front legs than hind legs. Those front legs actually are folded wings serving double duty. When the pterosaur took flight, it used front and hind limbs to leap high enough into the air to unfold its wings and begin flapping.
He proved what others thought impossible -- that the world's biggest-ever flying animal could take flight from a standing position. The key was his finding that the pterosaur, unlike modern birds, used four legs rather than two to get off the ground. Four legs made a runway unnecessary.
The entire research project began with Dr. Habib's interest in the biological limits of animals, which soon focused on the maximum possible size a flying animal could reach before becoming too large to fly. The largest species of pterosaur, known as the Quetzalcoatlus, captured his interest because it's about 15 times the size of the largest modern avian species.
First, Dr. Habib studied how existing birds and bats fly by using computer analysis and scans of current bird anatomy and fossils of giant pterosaurs, which lived 100 to 65 million years ago.
Today, the largest flying birds (as opposed to flightless ostriches) include the albatross, geese and turkey, which weigh up to 35 pounds, he said. Albatrosses and geese are waterborne fowl that use webbed feet, the water surface and wing flapping to launch themselves from their watery runways. Turkeys, however, take off from a standing position.
Slow-motion film of birds revealed to Dr. Habib that they leap an instant before they begin flapping their wings. The goal is getting high enough for the wing flapping to clear the ground.
Along the way, Dr. Habib said he learned about vampire bats, which have hind legs along with front legs that double as wings. The vampire bat uses all four limbs to leap 30 inches into the air before the wings unfurl and begin flapping.
"After I read literature on vampire bats and the work that a fellow researcher was doing on bats, it looked more like what was happening with pterosaurs," Dr. Habib said. "It's more powerful to use all four limbs to push off, then switch to using the arms as wings."
In the process, Dr. Habib discovered that modern birds' hind legs get stronger as the species gets larger. That's necessary because modern birds, unlike the pterosaur, use only hind legs for liftoff.
His research also revealed that the pterosaur's winged front arms were many times stronger and more muscular than its back legs. That variation from modern birds is a key reason why researchers were so puzzled by the pterosaur.
"If you are using all four limbs, it would be more efficient to bulk up front limbs because they do double duty," he said. "They push off, and they flap."
One reason why Dr. Habib's research achieved its notable ranking on the Discover Magazine list is its dual importance in biology and engineering.
And now that he lives in Pittsburgh, he's joined a research team that includes Carnegie Mellon University researchers to study better ways to make robots fly.
For now, that project, he said, "is getting off the ground -- pun intended."
First Published January 2, 2010 12:00 am