(ORDO NEWS) — For most of the history of paleontology, scientists believed that all dinosaurs were covered in scales, like modern lizards.
So it was until, as a result of a series of discoveries in recent decades, it turned out that many of these amazing extinct animals had ancient feathers – exactly the same as those of their later descendants, birds.
As for pterosaurs – the flying reptiles that ruled the skies during the time of the dinosaurs – the issue has never been resolved. Were they bald? Did they have feathers? The meager fossil evidence has never been conclusive – until now, scientists say.
Recently discovered fossils of Tupandactylus imperator, preserved on ancient limestone slabs in northeastern Brazil, provide evidence for the existence of feathers in pterosaurs around 113 million years ago.
“We didn’t expect to see this at all,” says paleontologist Oude Chincotta of University College Cork in Ireland.
“For decades, paleontologists have argued about whether pterosaurs had feathers. The feathers of our specimen finally close this dispute, as they are very clearly branched along their entire length, like in modern birds.”
Until now, researchers have more or less agreed that pterosaurs were covered in an outer layer of filamentous structures called pycnofilaments that may have resembled feather down, but whether these were the same as feathers was unknown.
The new Brazilian specimen seems to clarify this issue, showing not only single-stranded, whisker-like filaments sprouting from the cranial crest of the creature, but branched, distinctly feather-like structures not previously reported in pterosaurs, marked by short filaments radiating from central rod.
“This mode of branching is directly comparable to what is seen in stage IIIA feathers in modern birds, that is, with spines branching from a central rachis,” the researchers write in a new paper describing the discovery.
“This is strong evidence that fossil branching structures are feathers composed of rachis and spines.”
According to the researchers’ analysis, it is most likely that feathers were inherited from an avemetatarsal ancestor common to both dinosaurs and pterosaurs, although it is also possible that these traits evolved independently in different animal groups or species.
Speaking of features, faint traces of the ancient plumage of T. imperator seem to have kept a colorful secret hidden for many millions of years.
Examining the fossil using high-resolution electron microscopy, the researchers found numerous microbodies approximately 0.5-1 microns long in the soft tissues of the animal, which were interpreted as melanosomes – organelles containing melanin pigments responsible for the various body colors of animals.
The melanosomes were shaped differently (between monofilaments, branched feathers, and other tissues of the skull), suggesting that the pterosaur may have displayed different colors of its plumage.
“In modern birds and mammals, many of the dominant feather and hair colors are due to a limited range of chemically distinct forms of melanin,” explains palaeontologist Michael Benton of the University of Bristol in the UK, who wrote an editorial commentary on the new results.
While it’s impossible to say exactly how T. imperator benefited from colorful feathers more than 100 million years ago, Benton says the different colors on the prominent pterosaur crest may have contributed to inter-species signaling or other compelling aspects of animal communication.
“Perhaps they were used in mating rituals, similar to how some birds use colorful tail fans, wings and head crests to attract mates,” he writes.
“Modern birds are known for the diversity and complexity of their colorful shows and the role of these aspects of sexual selection in bird evolution, and the same may be true for a wide range of extinct animals, including dinosaurs and pterosaurs.”
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