A September 18 news release from the University of Southampton, UK, describes the study of the aerodynamic performance of feathered dinosaurs by researchers at the academic institution, which has offered a new approach to understanding the evolution of bird flight. The results of the study appear in the latest issue of Nature Communications in an article entitled, "Aerodynamic performance of the feathered dinosaur Microraptor and the evolution of feathered flight."
Recent fossil discoveries have altered the scientific community's view of the early evolution of birds and their power of flight. Scientists have discovered a number of small-bodied dinosaurs with feathers on their wings, legs, and tails, which are unique in the fossil record. However, even in light of new fossil discoveries, there is considerable debate regarding how these dinosaurs achieved flight.
University of Southampton scientists are confident that they have resolved the issue at the crux of the debate by examining the aerodynamic performance of the early Cretaceous five-winged paravian Microraptor. The dinosaur is the first theropod with feathers on five potential lifting surfaces: arms, legs, and tail. To scientists, Microraptor indicates that forelimb-dominated bird flight developed through a four-wing phase, and it represents an important period in the evolution of gliding and flapping.
In addition, the scientists at Southampton University executed a series of wind tunnel experiments and flight simulations on a full-scale, functionally accurate model of Microraptor. According to the results of the wind tunnel tests, Microraptor achieved its most stable gliding when generating large amounts of lift with its wings.
Although there has been considerable debate as to the position and orientation of Microraptor's legs and wing shape, the issue now appears to be irrelevant, as tests show that differences in these variables do not appreciably affect the dinosaur's ability to fly.
"Significant to the evolution of flight, we show that Microraptor did not require a sophisticated, 'modern' wing morphology to undertake effective glides, as the high-lift coefficient regime is less dependent upon detail of wing morphology," said Dr. Gareth Dyke, Senior Lecturer in Vertebrate Palaeontology at the University of Southampton and co-author of the study. "This is consistent with the fossil record, and also with the hypothesis that symmetric 'flight' feathers first evolved in dinosaurs for non-aerodynamic functions, later being adapted to form aerodynamically capable surfaces."
"What interests me is that aerodynamic efficiency is not the dominant factor in determining Microraptor's glide efficiency," adds Dr. Roeland de Kat, Research Fellow in the Aerodynamics and Flight Mechanics Research Group at the University of Southampton and co-author of the study. "However, it needs a combination of a high lift coefficient and aerodynamic efficiency to perform at its best."
