Paleontologists have examined the fossilized headcrest of Tupandactylus imperator, a species of tapejarid pterosaur that lived in north-eastern Brazil some 115 million years ago (Early Cretaceous epoch).
An artist’s reconstruction of Tupandactylus imperator, showing the feather types along the bottom of the headcrest: dark monofilaments and lighter-colored branched feathers. Image credit: Bob Nicholls.
Feathers are remarkable integumentary innovations that are intimately linked to the evolutionary success of birds and occur in diverse non-avian dinosaurs from the Middle Jurassic onwards.
The early evolutionary history of feathers, however, remains controversial as relevant fossils are rare.
Integumentary appendages in pterosaurs, traditionally termed pycnofibers, were recently reinterpreted as feathers on the basis of preserved branching but their homology with feathers is debated and their functions are unclear.
“For decades paleontologists have argued about whether pterosaurs had feathers,” said Dr. Aude Cincotta, a researcher at University College Cork, the Royal Belgian Institute of Natural Sciences, and the University of Namur.
“The feathers in our specimen close off that debate for good as they are very clearly branched all the way along their length, just like birds today.”
In their research, Dr. Cincotta and colleagues discovered that the bottom of Tupandactylus imperator’s crest had a fuzzy rim of feathers, with short wiry hair-like feathers and fluffy branched feathers.
“We didn’t expect to see this at all,” Dr. Cincotta noted.
Details of the cranial crest of Tupandactylus imperator from the Lower Cretaceous Crato Formation, Brazil: (a) incomplete cranium showing preserved soft tissue crest; (b-f) detail of the integumentary structures associated with the posterior part of the skull: (b) monofilaments, (c) branched feathers, (d) detail of curved branched feather in (c), (e, f) straight branched feather (e) with detail (f); white arrowhead in (e) indicates the basal calamus; (g-i) SEM of melanosomes in the soft tissues of the specimen: (g) ovoid melanosomes from the elongate fibers of the soft tissue crest, (h) elongate melanosomes from a monofilament, (i) ovoid melanosomes from a branched feather. Abbreviations: c – cristae; p – postmaxillary process; op – occipital process; s – skin. Scale bars – 50 mm (a); 5 mm (b); 2 mm (c); 250 μm (d-f); 2 μm (g-i). Image credit: Cincotta et al., doi: 10.1038/s41586-022-04622-3.
The scientists then studied the feathers of Tupandactylus imperator with high-powered electron microscopes and found preserved melanosomes, granules of the pigment melanin.
Unexpectedly, they found that the melanosomes in different feather types have different shapes.
“In birds today, feather color is strongly linked to melanosome shape,” said Professor Maria McNamara, a researcher at University College Cork.
“Since the pterosaur feather types had different melanosome shapes, these animals must have had the genetic machinery to control the colors of their feathers.”
“This feature is essential for color patterning and shows that coloration was a critical feature of even the very earliest feathers.”
The findings were published in the journal Nature.
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A. Cincotta et al. Pterosaur melanosomes support signalling functions for early feathers. Nature, published online April 20, 2022; doi: 10.1038/s41586-022-04622-3
Source link: https://www.sci.news/paleontology/pterosaur-colors-10733.html
