Dinos of a Feather

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Feathers are tied to the origin of Dinosaurs.  Now you understand my bird phobia.  They’re really just tiny dinosaurs.  Just think what a little reverse evolution could do.  My terror over hummingbirds is not irrational.  They’re just teeny tiny raptors.

“…Previously, scientists figured that feather-like structures and feathers evolved later in the dinosaur family tree, probably a couple times and just among saurischian dinosaurs. Now, if You’s interpretation of the Tianyulong fossil is right, it looks more like feathers evolved early in the dinosaur family tree at or before the saurischian/ornithischian split and were instead lost numerous times. Heterodontosaurs are thought to be one of the most evolutionarily basal (or primitive) groups among ornithischians.

“Finding something that looks like these feather-like features or proto-feathers in heterodontosaurs raises questions of whether the ancestral dinosaur was a fuzzy little animal,” Witmer said. “That’s a big surprise and it turns out that raises new questions, which either means that many dinosaurs then, in fact, lost this fuzzy little coat, or another option is that the ancestral dinosaur wasn’t covered in fuzz but what we see in this heterodontosaur might be a separate evolution of some sort of projecting epidermal filament.”

More and more of the feather-like structures in dinosaurs suggest that evolution is throwing unexpected curveballs, Witmer said, which begs the question of what gets called a feather.

“Sometimes new discoveries don’t clarify things. They make the picture cloudier,” he said.

For instance, it is unclear at this point if Tianyulong’s feather-like structures are part of the same evolutionary lineage as the feathers on today’s birds and the same lineage that yielded the proto-feathers on early theropods. Also, it’s possible that the Tianyulong feather-like structures really occurred under the skin, not outside it. That would change all these arguments, suggesting that the structures are collagen features in the skin, not feathery.

Witmer figures that dinosaurs are all very visually oriented animals and have visually oriented display structures. So it’s conceivable that these animals could have evolved feather-like structures independently, but the fact remains the feather-like structures look quite a bit like those found in predatory dinosaurs, he said.

“The reality is that dinosaurs may have evolved a variety of projecting integumentary appendages, things that stick out of the skin, and may have evolved them for a lot of the same reasons, for behavioral display or for regulating body temperature,” Witmer said. …”

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