Evolution took a long time: flying dinosaurs (Introduction)

by David Turell , Monday, May 29, 2017, 23:24 (2735 days ago) @ David Turell

In trying to fit in what we see in evolution we need to recognize the size of the gaps between the various stages of, for example, the series of changes from dinosaur to bird:

https://www.quantamagazine.org/20150602-dinosaurs-to-birds/

"It is worth studying. Recognizing the degree of complexity leads to recognizing the need for a sophisticated mind to plan the changes. The development of the feather alone is enough for me to reach that conclusion. It has be invented before flight develops. What use are feathers for the non-flying dinosaur, before he ability to fly develops? Not much if anything. The development of the feather is also highly complex when studied. Bones had to become lighter, metabolism revved up. The whole series of changes strongly suggests planning and teleology.

" Another dinosaur to bird essay is presented. Not worth quoting much but it shows neat pictures of the Chinese fossils that have been recently found. It turns out many dinosaurs were feathered, even non-fliers or gliders:

https://cosmosmagazine.com/palaeontology/jurassic-flight-school

" 'we now know of about 50 species of dinosaur for which there is direct evidence of feathers. Some have halos of fluff or beautiful fans of flight feathers delicately traced into their remarkable fossils; others have a distinctive pygostyle tailbone that would have been an attachment point for feathers; still others have bumps along their forearms – “quill knobs”, where feathers attach to ligaments in the wings of modern birds.

***

"Sinosauropteryx’s downy fuzz was probably used for insulation. In later models of dinosaurs, feathers also began to be used for display. The massive Gigantoraptor, an 8-metre-long, parrot-beaked omnivore found in the Gobi Desert of Inner Mongolia, for example, likely used great fans of tail feathers for mating displays. Only much later in the evolutionary process did feathers begin to be used for flight, such as in the four-winged, pigeon-sized dinosaur, Microraptor, found in 2000.

***

"It’s not clear what kind of flight mechanism these “bat” dinosaurs employed, but they may have used a mixture of gliding and flapping. Xu’s team attempted, without much luck, to make structural models based on the fossil, to test them aerodynamically. Now they are creating three-dimensional computer models instead. The experts also reappraised the handful of other scansoriopterygid fossils in light of what they know about Yi, but haven’t yet found direct evidence of the styliform element or membranous wings.

***

"The really big question is why this group evolved a second method of dinosaur flight when many closely related theropod lineages had species with very large flight feathers.

“'Why evolve a completely different flight mechanism and body plan?’ asks Xu. “This is really bizarre and, so far, I don’t have a good answer.” He believes that whenever big evolutionary transitions take place – such as that from terrestrial dinosaurs to flying birds –strange experiments take place to fill the new niche.

"Some of those experiments may well be recorded in the rocks of Hebei and Liaoning. “Yi qi was totally unexpected. We couldn’t believe it. If you know dinosaurs very well and the transition well, then you’d never expect there would be a dinosaur with bat-like or pterosaur-like wings instead of feathered wings. Discoveries like this will continue to emerge and demonstrate how complex the transition to birds was’, Xu says. “I would not be surprised if we find even more bizarre species in the future.'”

Comment: Evolution seems to try more than one way to advance a process.