New theory claims pterodactyls did not have feathers
The debate about when dinosaurs developed feathers has taken a new turn with a paper from the University of Leicester refuting claims that feathers were found on dinosaurs’ close relative, the flying reptiles called pterosaurs.
In a new paper published this week in Nature Ecology and Evolution, pterosaur expert Dr David Unwin from the University of Leicester’s Centre for Palaeobiology Research and Professor David Martill from the University of Portsmouth, question findings by Dr Yang and colleagues from Nanjing University, who presented their argument two years ago in the journal Nature Ecology and Evolution that pterosaurs had wings.
Experts from the University of Leicester argue that despite being able to fly, there is no clear fossil evidence of feathers being present on the wings of this creature, proposing that the ‘feathers’ are in fact tough fibres which form part of the internal structure of the pterosaur’s wing membrane.
Dr Unwin said: “The idea of feathered pterosaurs goes back to the nineteenth Century but the fossil evidence was then, and still is, very weak. Exceptional claims require exceptional evidence – we have the former, but not the latter.”
Dr Yang’s research shows that some pterosaur fossils show evidence of feather-like branching filaments, called ‘protofeathers’, on the animal’s skin.
This evidence rests on tiny, hair-like filaments, less than one tenth of a millimetre in diameter, which have been identified in only thirty pterosaur fossils. Yang and colleagues were only able to find three specimens among these, on which these filaments seem to exhibit a ‘branching structure’ typical of protofeathers.
However Dr Unwin and Dr Martill suggest that the ‘branching’ effect typical of protofeathers, may simply be the result of these fibres decaying and unravelling and therefore the evidence is insufficient from which to draw conclusions.
There are huge palaeontological implications to this debate; if pterosaurs did indeed have feathers as Yang suggests, this would mean that feather-like elements first evolved at least 80 million years earlier than currently thought.
It would also suggest that all dinosaurs started out with feathers, or ‘protofeathers’, but some groups, such as sauropods, subsequently lost them again – the complete opposite of currently accepted theory.
It would also mean that the very earliest feathers first appeared on an ancestor shared by both pterosaurs and dinosaurs, since it is biologically unlikely that something so complex could have developed separately in two different groups of animals.