Sinosauropteryx dino casts doubt on feather theory

From Nature:

Bald dino casts doubt on feather theory

Fossil calls into question the purpose of the first feathers

Katharine Sanderson

Feathery dinosaurs might not have been as common as experts thought, according to researchers who analysed a fossil of a creature previously thought to have feathers, and found instead that it was bald.

The discovery calls into question the theory that the first feathers evolved not for flight but for insulation, and that they made their first appearance in relatively early dinosaur lineages that later evolved into modern birds.

If these dinosaurs didn’t have feathers, or feather-like structures, then feathers may have evolved at a later time, and been used for flight right from the start.

The fossil represents a dinosaur called Sinosauropteryx, which lived in the Early Cretaceous period roughly 140 million years ago.

The specimen, found in Liaoning Province, China, has distinctive patterns seen in its skin.

Previous studies of other related dinosaurs with similar markings have led experts to conclude that these dinosaurs were covered with downy ‘protofeathers’.

But Theagarten Lingham-Soliar from the University of KwaZulu-Natal in Durban, South Africa, and his colleagues now say otherwise.

Instead, they argue that these structures are degraded remains of collagen fibres, the main connective tissue in animals.

Decomposing theory

Lingham-Soliar and his colleagues produced high-resolution microscopic images of the fossil that, he says, show that these structures represent degraded soft tissue.

The regular pattern of the fibres suggests that Sinosauropteryx had a frill of skin along its neck, back and tail.

And the random orientation of some of the fibres, previously attributed to protofeathers, are more likely to indicate breakages in the regular pattern of collagen fibres as the dinosaur decomposed.

The researchers also say that the absence of herringbone-shaped patterns — which would be seen if feathers were present — puts another nail in the coffin for the protofeather suggestion.

They publish their findings in Proceedings of the Royal Society B1.

If Sinosauropteryx was indeed featherless, then it may be that feathers arrived on the evolutionary scene later than palaeontologists had thought.

If there will be a sequel to the Jurassic Park movies, they may have to take all those feathers off again …

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