Saturday, January 18, 2014

When Did Birds Learn To Fly?

There's  no news from Another Bird Blog today as I am "Out of the Office". However here is a post with a fascinating piece of information for those interested in the history and evolution of birds.

A study into the aerodynamic performance of feathered dinosaurs, by scientists from the University of Southampton, has provided new insight into the evolution of bird flight. 

“In recent years, new fossil discoveries have changed our view of the early evolution of birds and, more critically, their powers of flight. We now know about a number of small-bodied dinosaurs that had feathers on their wings as well as on their legs and tails: completely unique in the fossil record. However, even in light of new fossil discoveries, there has been a huge debate about how these dinosaurs were able to fly. 

Scientists from the University of Southampton hope to have ended this debate by examining the flight performance of one feathered dinosaur pivotal to this debate — the early Cretaceous five-winged paravian Microraptor. The first theropod described with feathers on its arms, legs and tail (five potential lifting surfaces), Microraptor implies that forelimb-dominated bird flight passed through a four-wing (‘tetrapteryx’) phase and represents an important stage in the evolution of gliding and flapping. 

The Southampton researchers performed a series of wind tunnel experiments and flight simulations on a full-scale, anatomically accurate model of Microraptor. 

Results of the team’s wind tunnel tests show that Microraptor would have been most stable gliding when generating large amounts of lift with its wings. Flight simulations demonstrate that this behaviour had advantages since this high lift coefficient allows for slow glides, which can be achieved with less height loss. For gliding down from low elevations, such as trees, this slow, and aerodynamically less efficient flight was the gliding strategy that results in minimal height loss and longest glide distance. 

Much debate, centred on the position and orientation of Microraptor’s legs and wing shape turns out to be irrelevant – tests show that changes in these variables make little difference to the dinosaur’s flight. 

Dr Gareth Dyke, Senior Lecturer in Vertebrate Palaeontology at the University of Southampton and co-author of the study, says: “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.” “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.” 

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, says: “What interests me is that aerodynamic efficiency is not the dominant factor in determining Microraptor’s glide efficiency. However, it needs a combination of a high lift coefficient and aerodynamic efficiency to perform at its best.” 

The paper ‘Aerodynamic performance of the feathered dinosaur Microraptor and the evolution of feathered flight’ is published in the latest issue of Nature Communications. Dr Dyke and fellow Southampton palaeontologists showcased their ground-breaking research at the Celebrating Dinosaur Island: Jehol-Wealden International Conference on 21 and 22 September 2013. 

The Isle of Wight (Dinosaur Island) and China are key areas for Cretaceous fossils, especially dinosaurs. To celebrate this connection, Chinese and UK dinosaur palaeontologists will discuss their research at the National Oceanography Centre, Southampton and visit key dinosaur sites on the Isle of Wight and network with tourism and business leaders to build connections for future paleontological research.”

No one should accuse Another Bird Blog of offering its readers a varied diet of birds.

Log in soon for more news, views and photos, this time somewhere warm and sunny. 


eileeninmd said...

Great information and post, Phil! I would like to be somewhere warm right now. Have a happy weekend!

Dave Lewis said...

Warm and sunny? Must not be in Ohio...

KK said...

This learning to fly article reminds me of Leonardo da Vinci, who himself was very impressed by the flight of birds and tried to create machines that could fly.

Wally Jones said...

Extremely interesting subject!

I just read an article on the continuing debate about whether dinosaurs evolved into flying creatures from the "ground up" or from the "trees down".

The terrestrial theorists posit that feathers likely developed for insulation and to assist in grasping prey. Then, the ground-dwellers discovered as they ran after a meal and "flapped" their forelimbs to catch it, they became airborne.

Those supporting the arboreal side of the issue think that since fossil records show some theropods had "grasping" feet, they would have been able to perch on a tree branch and learned they could glide down to their unsuspecting prey.

"Another Bird Blog" once again provides up-to-the-minute news about our avian friends!

Stay warm, Phil - hug your spouse a lot!

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