In today’s Academic Minute, Dr. Gareth Dyke of the University of Southampton explains how a newly discovered fossil is complicating the story of how and when flight evolved.
Gareth Dyke is a senior lecturer in vertebrate paleontology at the University of Southampton where his research addresses the evolutionary history of birds and their dinosaurian relatives. His research has been widely published and he holds a Ph.D. from the University of Bristol.
Dr. Gareth Dyke – Dinosaurs and Flight
The origin of flapping and gliding flight in birds is hugely debated by evolutionary biologists and palaeontologists. In order to evolve flapping, birds needed to develop a complex suite of muscles in their chests and arms; all features inherited from their dinosaur ancestors. This much, at least, we do know: living birds are the descendants of the theropod dinosaurs – fast running, meat-eating carnivores like T rex and Velociraptor.
Over the last 15 years or so, new fossil discoveries – especially from rocks around 120 million years old and in China – have revolutionised our view of the early history of birds and their ancestry. We know vastly more about the anatomy of dinosaurs, early birds and can speak with authority on complex questions like the evolution of feathers. Most of the known groups of theropod, or beast-footed, dinosaurs possessed feathers of some kind or another, for example; T rex was likely covered in a downy feathered coat, more like a giant chick than a lizard.
New fossil discoveries have not yet provided an answer to the age old question of bird flight origins, however. If anything, new fossils of dinosaurs and early birds have made this puzzle more complex – flight, of various kinds including gliding and flapping, appears to have been widespread amongst small dinosaurs. Gone are the days when palaeontologists debated the ‘trees-down’ versus ‘ground up’ hypotheses for bird flight origins.
Our most recent discovery, a small feathered dinosaur called Eosinopteryx, further complicates the story. Eosinopteryx was a small, running dinosaur that had well-developed feathers, but not on its legs. This was an animal that had developed feathering but that was likely not using its legs for gliding, like many similar small dinosaurs. Even more confusing, our evolutionary analysis shows that Eosinopteryx and Archaeopteryx, long considered 'the first bird', are not birds at all, but more closely related to other small-bodied theropod dinosaurs.
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