Flashy flyers: introducing pterosaurs with coloured feathers

If you got in a time machine and travelled to Brazil in the Early Cretaceous, about 145–100 million years ago, you might be dazzled by stunning flying pterosaurs showing off their coloured plumes.

A study published today in Nature has found the first evidence for feathers with varied pigmentation on pterosaurs, suggesting they used them for display as well as for regulating body temperatures. This research provides new insight into how coloured feathers evolved in pterosaurs’ distant cousins: birds.

Despite swooping around during the Cretaceous, pterosaurs are not dinosaurs, which means they are not birds either. These flying reptiles took to the sky with wings formed of a skin membrane that stretched between their extended forearms, back legs, and body.

Professor Maria McNamara and Aude Cincotta of University College Cork, Ireland, and their colleagues made the discovery that pterosaurs might have had coloured display feathers while studying the skull of a Tupandactylus cf. imperator.

This creature would have been incredibly impressive. It had a five-metre wingspan and a giant head crest that would put any modern-day hornbill to shame.

In their paper the authors write that the fossil had “remarkably well-preserved soft tissues”, and this allowed them to examine the feathers down to a microscopic level. They found both soft downy feathers, and branched feathers similar to those of birds living today.

Pterosaur feathers
Scanning electron micrographs of melanosomes in the soft tissues of MCT.R.1884. a–c, Elongate melanosomes from monofilaments. d–f, Ovoid melanosomes from the branched feathers. g–i, Ovoid melanosomes from the soft tissue crest (area 1, Extended Data Table 2). Scale bars, 2 μm. Credit: Cincotta et al., Nature 2022

It has long been known that pterosaurs had fluff insulating their bodies, but characterisation of that fluff has been controversial, writes palaeontologist Professor Michael Benton in a letter to Nature responding to the research: “…the detail of the regular branching in these structures inserted in the skin provides support for their identification as feathers”.

Colour pigments are created by structures called melanosomes. In today’s birds, different types of melanosomes produce different coloured feathers. The pterosaurs had different types of melanosomes, suggesting that just like some birds, these reptiles also had coloured feathers.

In birds, colour is often used for signalling information between individuals; if pterosaurs also possessed vibrant colours it’s likely they had the same function.

Feather research can get scientists all a flutter: “The early evolutionary history of feathers, however, remains controversial as relevant fossils are rare,” write McNamara and Cincotta. Fear of controversy did not stop the researchers from suggesting a bold idea: feathers might be far older than we thought, going back to the Middle to Late Triassic (around 247–201 mya), when pterosaurs and dinosaurs last had a common ancestor.

Benton writes that a series of studies over the last 25 years has “shifted the origin of feathers to 100 million years earlier than was originally thought on the basis of the discovery of the earliest-known bird fossil, that of Archaeopteryx, which lived in Germany around 150 million years ago”.

Feather research often focuses on the use of feathers for flying, but as Benton writes: “This new evidence will probably lead to a refocusing on the capacity for insulation that feathers provide as being, presumably, the main reason for their development, followed by their use for signalling.”

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