It's probably not the first thing that comes to mind when you get up in the morning, but for palaeontologists, it's a long-standing scientific dispute that keeps many up at night: did pterosaurs, the cousins of dinosaurs, have feathers or not?
A landmark discovery by a Belgian-Brazilian research team will, at last, let many historians sleep better: yes, pterosaurs had feathers. The finding was led by palaeontologist Aude Cincotta, from the Royal Belgian Institute of Natural Sciences. And the repercussions are resonating throughout the palaeontology field. Here’s why…
The pterosaur was a flying reptile and a close relative of dinosaurs, which lived about 225 million years ago, and became extinct at the end of the Cretaceous period some 66 million years ago when an asteroid hit the earth. The pterosaurs were diverse in size, from very small to up to more than 10 meters in wingspan. They are considered the first vertebrates capable of flying.
It all begins with the analysis of a fossil of Tupendcatylus imperator, a pterosaur, which lived 155 million years ago in north-eastern Brazil. The skull fossil, very well preserved, arrived at the Royal Museum of Natural Sciences of Belgium after having belonged to a private individual. The team then had the skull repatriated to Brazil and chose to analyse it with scientists from the country from which it came.
The Belgian-Brazilian team made a discovery about the soft tissues of the fossilised ridge: there were two types of feathers there. Elongated filaments without branches – and branched feathers. This was the breakthrough because, until now, it was not known that pterosaurs had branched feathers. These were known to be present only in some carnivorous dinosaurs, the ancestors of today's birds, called theropods.
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The team made another important find: the pterosaurs had coloured feathers, which were probably used to get noticed. Indeed, by analysing the material, scientists discovered fossil melanosomes, microscopic structures found in the skin and in certain organs, and which contain a pigment called melanin.
It is the shape of melanosomes that strongly contributes to the colour of feathers in birds today. And in the pterosaur analysed, these melanosomes had different shapes (elongated, oval or spherical). The first feathers therefore already had quite varied colours.
This story is, therefore – quite literally – a feather in the cap for the team of palaeontologists who published it in the prestigious journal Nature. Until now, it was thought that only theropod dinosaurs had these feathers of different shapes and colours.
"This discovery places the origin of feathers much further back, on the timeline" says Aude Cincotta. "Knowing that dinosaurs and pterosaurs have a common ancestor, this common ancestor must have already had feathers. This is really one of the major results of the study."
The publication will certainly be read with great attention by palaeontologists who until now defended the opposite thesis, namely the absence of feathers in pterosaurs. As recently as September 2020, another article in Nature – this time by the British duo David Unwin and David Martill – expanded on the no feather claim under the title "No protoplumes in pterosaurs".