Recent scientific research has revealed a little more on the evolutionary origins of birds. Dinosaur fossil discoveries seemed to raise a great many questions, regarding the transition of dinosaurs to birds. In the hope that this adaptation might be more comprehensively explained, researchers operating from the University of Southampton, England, devised a properly scaled Microraptor model to perform flight simulations using wind tunnels.
The researchers published their paper, which was entitled aerodynamic performance of the feathered dinosaur Microraptor and the evolution of feathered flight, in the journal Nature Communications.
Microraptors were small, five-winged dinosaurs, estimated to have roamed the Earth some 120 million years ago. The winged beasts were approximately two to three feet in length, weighing in at around one kilogram. A study performed by Sankar Chatterjee and R. Jack Templin of the Department of Geosciences in Texas Tech University, Canada, regard the Microraptor to be one of the smallest non-avian dinosaurs ever to have existed.
A number of well preserved Microraptor fossils have been unearthed, many of which have been located in Liaoning, China. These findings are particularly important, as they have permitted researchers to derive a relationship between birds and dinosaurs.
Researchers believe the Microraptor possessed pennaceous feathers, comprising of both stalk and feather segments. The hollow, basal section is called a calamus, and remains anchored underneath the animal’s skin. These feathers provided the creature an aerodynamic advantage, and were located on the arms, legs and tail. For added stability, during flight, the dinosaur also employed a diamond-shaped fan, located at the terminus of its thin tail.
This led Xiu Xing, a Chinese paleontologist, to suggest that the dinosaur was capable of utilizing all of its feathered limbs to achieve flight.
Wind Tunnel Testing
In terms of actual flight performance, however, details on the Microraptor remain sparse. It is well known that the Microraptor was more closely related to birds than it was Theropods (a bipedal suborder of dinosaurs), like velociraptors.
Researchers from the University of Southampton wanted to understand the intricacies of the dinosaur’s flight; it was hoped, in turn, that this could provide clues on the evolution of flight.
In addition, the researchers believe their results could provide answers to a longstanding question. Did birds pass through what is known as the four-winged Tetrapteryx stage? This theory stemmed from William Beebe, an American naturalist, who talked about the phenomenon at great length in his The Origins of Birds book.
The group went about constructing an realistically proportioned, anatomically accurate Microraptor model. Using a series of wind tunnel flight simulations, the group established that the animal was able to generate substantial lift in its wings. On this basis, it is hypothesized that the Microraptor was capable of gliding for short bursts, without dropping height.
The researchers were also interested in testing to see whether the Microraptor’s wing dimensions or leg placement had an impact upon flight. The five areas of lift (four across the wings, and one from the tail) have been a source of intrigue over the years, with a number of prominent scientists suggesting that it was not possible to achieve flight with such physiology.
Gareth Dyke, who was one of the co-authors on the study, believe his group successfully demonstrated that the Microraptor “… did not require a sophisticated, ‘modern’ wing morphology to undertake effective glides…” and relied principally upon lift to glide from place to place.
In addition, according to Red Orbit, researchers from McGill University recently demonstrated the evolutionary mechanism involved in the transformation of regular limbs into wings. Following the analysis of Maniraptor fossils, Professor Hans Larsson established that the forearms became elongated, whilst the hind limbs gradually decreased in size. Larsson maintains the forearms eventually evolved to become wings, whilst the hind limbs provided extra stability, whilst engaged in flight.
Ultimately, these wind tunnel experiments have improved the research group’s knowledge of the Microraptor dinosaur’s flight performance considerably. In the future, it is hoped that a deeper understanding of these evolutionary changes could offer even greater insight into precisely how birds evolved from dinosaurs.
By: James Fenner