A THEORY OF FLIGHT

 From those digs, Chatterjee has found dozens and dozens of remarkable fossils, including North America’s first-known, bird-hipped dinosaur, which he gave the moniker Technosaurus, in honor of his academic home. He further found and named the earliest toothless dinosaur, Shuvosaurus, (named after his son, Shuvo, who found the specimen as a young child); and the terror of the Triassic, Postosuchus, (named after the town of Post), and its bite-sized prey Rileymillerus, (named after the rancher Riley Miller). Rocking the Earth’s biological clock, Chatterjee made a major discovery when he found Protoavis texensis (the first bird from Texas), the world’s oldest known bird species considered to be the ancestor to modern birds. Protoavis looked half-dinosaur, half-bird, reinforcing the hypothesis that birds evolved from dinosaurs. With the find, Chatterjee set back the Earth’s biological clock and dated the fossil to be from 225 million years ago. The find meant that birds and dinosaurs may have had a common ancestor, though the original life form remained a mystery. In the same site where he found Protoavis, Chatterjee also found two of the earliest dinosaurs. What Chatterjee had not encountered while sifting through his findings from the field were preserved feathers of the flying creatures.

Chatterjee proclaims ours to be the enchanting land that heralded the age of dinosaurs. “Here in West Texas, it was a flowing river. These animals died because they had been in a flash flood with very high energy. You never find feathers in this condition. The Caprock was once part of a lush tropical area dotted with flowing rivers and lakes. The abundance of fossils it contains indicates many creatures were trapped together. Most people in this region do not know that early dinosaurs lived around the edge of the Caprock.”

Chatterjee contended in his 1997 book, “The Rise of Birds: 225 Million Years of Evolution,” (The Johns Hopkins University Press), that Protoavis, a pheasant-sized creature, may be the long-lost ancestor of all birds. “In my book, I predicted that the ancestor of the bird would be a small dinosaur that evolved into being able to climb trees,” Chatterjee recalls. “In China, scientists found exactly the same thing I had predicted, a small, climbing feathered theropod, ancestral to all birds. They found not one, but hundreds of thousands, of chicken-sized dinosaurs, with full feathers of different stages, from downy feathers to contour feathers to asymmetric flight feathers. Outside of Beijing, in an area in the Liaoning Province Chatterjee dubs as “Cretaceous Pompeii,” ancient lake beds enfold hundreds of feathered dinosaurs, early birds, pterosaurs, mammals, fish, insects and plants. The specimens were preserved exquisitely, entombed by occasional volcanic eruptions. “Exactly the same thing that happened in Pompeii also happened at the Liaoning fossil site. Ash has a property of preserving everything, and in China, we can see layer after layer of complete skeletal fossils that are just mind-boggling,” Chatterjee explains. “The animals lived near a large lake in a forest, with a volcano nearby. Every two or three years, the volcano ruptured, and the poisonous gas from volcanoes killed everything. All the birds and dinosaurs fell into the lakes, went to the bottom and were covered by ash beds. I was fortunate to visit the Liaoning site, which is probably the most important paleontologic discovery in the 20th century, and to work on the flight mechanisms of these feathered dinosaurs.” Chatterjee and Templin published recently through the University of Indiana Press, published a landmark paper on the flight performance of the feathered dinosaurs from China, which appeared in an edited volume, “Feathered Dragons,” referring to the pterosaur finds.

Soon after the announcement of his major find of Protoavis, Chatterjee was quoted in a Boston Globe magazine article as attributing his paleontological successes of finding new species simply to luck. However, while that intangible quality may be a part of digging up dinosaurs, University of Colorado paleontologist Robert Bakker noted at the time, “Sankar has a halo around his head.”

Finding so much Triassic life in West Texas, Chatterjee soon garnered the attention of the National Geographic Society, which funded the Post quarry throughout the 1980s, along with the National Science Foundation, the National Geographic Foundation, the Smithsonian Institution, and the Dinosaur Research Society, among others. Chatterjee also recognizes the friendliness and support of the local ranchers for his paleontologic research. His work since has been featured in documentaries produced by the National Geographic Society, Public Broadcasting Station’s NOVA and the Discovery Channel, and his publications have been accepted to numerous prestigious scientific journals, such as Science, Nature, Scientific American, Discovery and Geological Society of India. News of his finds have been covered by respected media, such as CBS, CNN and PBS, Time, New York Times, Life, London Times, Pravda, World Book and Encyclopedia Britannica. For his scientific contributions, Chatterjee has received numerous honors and awards including the Antarctic Service Medal, Headliner Award, Elected Fellow of the Geological Society of America and the American Association for the Advancement of Science, Scientist of the Year Award and Honorary Member of the Golden Key National Honor Society.

The current scholarship by Chatterjee and Templin again is fetching the attention of the National Geographic Society documentary filmmakers and the world of science. “For 1,000 years we envied birds because they could fly, and no doubt, watching birds fly, we invented the plane,” Chatterjee says, pointing out that NASA officials will build future aircraft based on this natural model of flight for the first time. Complex and difficult, NASA’s designers and engineers will be attuned to the researchers’ observations that pterosaurs and birds did not have fixed wings, like today’s aircraft. Instead, the creatures had flexible wings that could fold into the body as well as expand into limbs required for flight. They evolved into being able to twist their wingtips to take advantage of the forces of thrust and drag, in the same way that humans turn their hands as they swim.

Chatterjee and his colleague, Larry Witmer of Ohio University, now are applying the same CT scan used by modern medicine on humans to study the brains of pterosaurs. Using the scan to create the virtual brain from the brain cavity in three-dimensional form, Chatterjee and Witmer are able to see for the first time how the brain of a pterosaur is structured. “The brain is the most complicated and the most amazing organ of the vertebrate body and provides information about physiology, behavior and intelligence. Simply studying the morphology of the brain, we can tell, for example, how intelligent the animal was, its head posture, and whether the animal could fly,” Chatterjee notes.

Although pterosaurs have been found all over the world, scientists knew hardly anything about their brains, even though they knew about their anatomy. Pterosaur fossils generally are found in two-dimensional form, as a paper-thin sheet, because the inside of the bones are entirely hollow (necessary for flight) and become crushed under layers of time. With new finds of pterosaur fossils in China and Brazil of wholly preserved three-dimensional skulls and skeletons with intact wings, paleontologists were able to reconstruct the paper-thin wings in cross-sections. “Like any soft part of a body, such as blood and muscles, skin is fragile, delicate and normally is not preserved in fossils,” Chatterjee notes. “Pterosaurs’ wings are made of leathery skin, like bats, but the creatures are closer to birds than bats from an evolutionary point of view. Like birds, pterosaurs are born with hollow and very delicate bones, however the skin on their wings is reinforced by a kind of rod, called actinofibrils,” Chatterjee says. “The rods in the wings indicate that pterosaurs could tuck in their wings and fold out their wings, in the same fashion that an umbrella opens and closes. Such reinforcingrods are lacking in the bat wings; this is probably why bats never became large.”

Through their complex calculations, Chatterjee and Templin studied the aerodynamics, postures and brains of pterosaurs to determine whether they could hover, flap, glide or soar on their wings, as well as answer how the animals walked on land. Studying the 10 species of pterosaurs, from the smallest to the largest, the researchers examined footprints, wing designs, brains, the inner ear, stereoscoping vision, the orientation of the head, as well as environmental air patterns, or thermals, among many other factors, in determining how animals gained the ability to fly. “Throughout time many animals tried to conquer the air. The animal has to defy gravity with the use of a wing that gives the animal lift and thrust. The emergence of flight among birds and pterosaurs happened independently and separately as the different species evolved in their designs to be able to fly,” Chatterjee observes. “In science, we call this convergence. In other words, in nature only a few solutions are available for a creature to achieve a goal, for example, going through water. Just one or two designs have been invented by fish to maneuver through water. That streamlined body design of fish has been copied by marine reptiles, such as plesiosaurs, and marine mammals, such as dolphins and whales.”

Citing the glories of the ancient birds and flying pterosaurs, Chatterjee reveals that the modern creatures that fill the skies have adapted with variance as well. For example, Canada Geese fly 5,000 miles from the North Pole to the South Pole each year in their recognizable V-formation, an economical method of sharing the force of the headwind that the flock naturally flies toward. The Albatross, with its huge eight-foot wingspan, sails on the winds above the oceans without stopping for six to 12 months, as it snatches its food from the water and vanishes into the skies. The Loon is the only bird in the age of dinosaurs still around us, having escaped extinction for millions of years. Showing no evolutionary change, the Loon is a living fossil that first appeared in Antarctica, as suggested by Chatterjee’s discovery of Polarornis. Their ability to fly made possible their migration to the Arctic when Penguins appeared in the south, competing for fish. Scientists have found no evidence of Loons south of the equator for the last 60 million years.

Birds and their implications for human flight are intricately connected to the plate tectonics and early exploration of Antarctica, the evolution of feathers and wings in the Earth’s earliest flying creatures, and the human-made aircraft designs patterned after nature and her secrets.

On Antarctica, decades ago, Admiral Byrd named a 4,085-foot-high summit “Mount Wade” after the geologist. Among the letters that Chatterjee first found upon arrival at Texas Tech was one addressed to Wade from Wernher von Braun (1912-1977), one of the most important rocket developers of all time. Von Braun was searching for a secretive locale to help train the United States’ earliest astronauts. Wade pointed von Braun to Antarctica.

Aware that his contributions to science may not transfer into the technology of building advanced space vehicles in his own time, Chatterjee nevertheless dreams the visions of a pioneer both in his study of the deep past and in his contributions to the far future.

Explorations of the Earth’s deep crust and its time-covered creatures, of Antarctica’s dry desert and frozen wilderness, and of space’s amazing planets and limitless frontiers are fixed in an extraordinary relationship, wrapped in the common threads of dinosaurs and discovery, completing the tapestry of Sankar Chatterjee’s life.

OF SPECIAL NOTE:
Sankar Chatterjee presented his research findings at the 2005 Geological Society of America’s annual meeting in Salt Lake City, Utah. See "Wright Bros. Upstaged! Dinos Invented Biplanes" at the GSA Web site.