Many Cretaceous birds, such as Confuciusornis (center) and these enantiornithines,
had pairs of tail streamer feathers that may have easily been detached in moments of peril
Posted on 12/14/2018 2:52:50 PM PST by ETL
One hundred million years ago, the sky was filled with birds unlike those seen today, many with long, streamerlike tail feathers. Now, paleontologists have found examples of these paired feathers preserved in exquisite detail in 31 pieces of Cretaceous amber from Myanmar. The rare 3D preservation reveals the feathers’ structure is completely different from that of modern feathers—and hints that they may have been defensive decoys to foil predators.
Such tail streamers—in some cases longer than the bodies—have been observed in early bird fossils from China for several decades, in particular, the 125-million-year-old Confuciusornis sanctus. They may also be present in some feathered dinosaurs. Scientists have long thought the feathers were ornamental, similar to the tail feathers in some modern hummingbirds and birds of paradise—and that they may have been unique to either males or females, as only a subset of fossils of some species possess them.
But most of those fossils are squished almost flat, making the structure of the feathers near impossible to study. “These new discoveries change the game—the fossils are astoundingly beautiful,” says Steve Brusatte, a palaeontologist at the University of Edinburgh who was not involved in the work.
Now, an international team of researchers, led Lida Xing at the China University of Geosciences in Beijing, have analyzed these feathers, many of them found paired, in 31 pieces of 100-million-year-old amber from Myanmar. “They are the weirdest feathers I have ever seen,” says co-author Jingmai O’Connor, who studies fossil birds at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing.
In most of the conventional fossils with tail streamers from China, the birds and their feathers are squashed almost totally flat. “The way we interpreted these feathers from compression fossils was basically completely, entirely wrong,” O’Connor says. “Looking at them in three dimensions preserved in amber, I was astonished.”
In all modern feathers, the central shaft or rachis is a hollow tube. But the ancient ribbonlike tail feathers are fundamentally different, with a shaft that’s more like a half-cylinder, flattened and open on one side. They also have significantly reduced feather barbs on either side of the shaft, compared with modern flight feathers. These tail streamers would have stuck out straight and rigid, like an extended tape measure, explains co-author Ryan McKellar of the Royal Saskatchewan Museum in Regina, Canada.
But the streamers were also insanely thin. “The thickness of the rachis in some specimens is 3 microns thick. That’s less than the size of the average cell,” O’Connor says. (Human red blood cells are about 7.5 microns thick.) “How could something be so thin and maintain structural integrity?” She believes the thinness and the half-formed shaft were a way to economize, making the feathers much less energetically demanding to produce.
As the authors argue today in the Journal of Palaeogeography, the thin shaft and other clues suggest these feathers were highly disposable, similar to the detachable tail of a lizard, and may have helped ancient birds escape the clutches of predators. The fact that so many paired streamers have been found in amber—fossilized tree resin—without the body of the bird, suggests they were plucked out easily when stuck in the resin. To McKellar, that suggests a defensive role. “You’re giving the predator a nonlethal target that’s half the size of your body.”
That’s a speculative idea, says Gerald Mayr, an ornithologist at the Senckenberg Research Institute and Natural History Museum in Frankfurt, Germany. But he finds the half-open feather shafts highly intriguing. “This [structure] suggests significant developmental and functional differences to the feathers of living birds.”
Unusual feathers preserved in 100-million-year-old Cretaceous amber could have been used as defensive decoys
Pierre Cockx/RSM
Like modern birds, Confuciusornis had a toothless beak, but close relatives of modern birds such as Hesperornis and Ichthyornis were toothed, indicating that the loss of teeth occurred convergently in Confuciusornis and living birds.
It is the oldest known bird to have a beak.[1] It was named after the Chinese moral philosopher Confucius (551–479 BC). Confuciusornis is one of the most abundant vertebrates found in the Yixian Formation, and several hundred complete, articulated specimens have been found.[2]
Distinguishing traits
Confuciusornis shows a mix of basal and derived traits. It was more “advanced” or derived than Archaeopteryx in possessing a short tail with a pygostyle (a bone formed from a series of short, fused tail vertebrae) and a bony sternum (breastbone), but more basal or “primitive” than modern birds in retaining large claws on the forelimbs, having a primitive skull with a closed eye-socket, and a relatively small breastbone.
At first the number of basal characteristics was exaggerated: Hou assumed in 1995 that a long tail was present and mistook grooves in the jaw bones for small degenerated teeth.[7]
Skull
The skull of Confuciusornis was equipped with a pointed toothless beak. It was relatively heavy-built and immobile, incapable of the kinesis of modern birds that can raise the snout relative to the back of the skull. This immobility was caused by the presence of a triradiate postorbital separating the eye socket from the lower temporal opening, as with more basal theropod dinosaurs, and the premaxillae of the snout reaching all the way to the frontals, forcing the nasals to the sides of the snout.[8]
The sublime efficiency of nature seems boundless, at least to me it does. It’s helpful and intriguing when you post here on such topics.
A good engineer may incorporate such constructions into ways that produce better aircraft.
Off Topic: I read about an inventor who looked at how a cat’s tongue scooped water from a pool. This lead to Virgina Tech, MIT and Princeton collaborating on a study featuring gravity issues. The lapping of domestic cats is governed by the competition between inertia and gravity, wrote Sunghwan Jung, Asst. Prof. of engineering science and mechanics at Virgina Tech. In essence, this action shows a ‘way of defeating gravity!”
As seen in Virgina Tech Daily, Nov. 12, 2010.
“If a French Poodle and a Bantam Rooster had a Baby.....”
Bkmk
The ground nesting birds that I’m familiar with all have white tail feathers under darker ones. When they flush, they flare their tails, giving predators a visual effect to grab at. I’ve seen cats spitting out mouthfulls of tail feathers.
Looks like scissor tails to me.
Remarkable how leftists can be avowed evolutionists yet at the same time demand central planning to solve all problems.
Hayek’s emergent order not only proscribes a healthy political economy, it explains evolution.
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Life finds a way!
Typical Chinese quality control...
Thanks ETL. And looky, some stupid jackass put "piltdownman" in the keywords again.
Excellent point. Thanks.
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