The Barbarian
Crabby Old White Guy
- Apr 3, 2003
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For Barbarian:
I wrongly attributed the word biologically to you.
Well, let's take a look...
Barbarian, earlier:
That excuse won't work for you. You see, the fact is, scutes and feathers are alike genetically, biochemically, and anatomically, that a single mutation can reverse the process.
nolidad's false attribution...
I call falsehood to your claim that feathers and scutes are genetically, anatomically and biologically identical.
Did you think no one would notice the difference?
Barbarian observes:
No. Gas bladders in fish are vestigial lungs (many fish still retain functional lungs, and lack gas bladders, which are merely lungs that no longer do respiration, but maintain bouyancy)."
Close enough to be synonymous with biologically alike (inherited)
Yep...
New research that uses computed tomography (CT) technology goes a long way toward showing that lungs and gas bladders in fish are variations of the same organ.
Researchers say one of the great problems of evolution is to understand how the major features of organisms have changed over great swaths of time. How did limbs evolve from fins? How did bird feathers arise from scales?
The lung is a major organ of great functional importance for vertebrates (animals with backbones). For 150 years biologists have debated the idea that in living fishes, gas bladders—internal bags of air to which fishes can add or eliminate oxygen to control buoyancy—are simply a modified version of an ancestral pair of lungs. Some have argued that the two are completely different organs.
By proving that several ray-finned fishes, namely sturgeons and paddlefishes, as well as bowfin, have pulmonary arteries like those that supply the lungs of vertebrates, researchers show that the common ancestor of all these fishes must have originally had lungs supplied by a pulmonary artery.
The arteries in gas bladder fish, therefore, are actually vestigial pulmonary arteries that have been co-opted for new functions. The researchers hypothesize that this evolutionary change occurred either by the loss of respiration or by dorsal shifts in the anatomical structures of these fishes.
...
Scientists have known about the vestigial arteries for a long time, but because traditional dissection and corrosive casting techniques lose detail, no one made the connection with pulmonary arteries, says Sarah Longo, the paper’s lead author, who conducted the research as a student at Cornell. Longo is now a graduate student at the University of California, Davis.
Traces of ancient lungs in fish bladders - Futurity
And as I showed you from evolutionary web sites a single mutation cannot undo the process.
You're a little behind, again...
After performing a complete genetic analysis of chickens and alligators as they develop in eggs, the researchers identified key genes involved in feather formation.
They then placed these chicken feather genes in alligator eggs, with the goal of prompting the scales on the growing reptiles’ skin to develop into feathers.
As a result, some of the scales grew into structures “similar to the unusual filamentous appendages found in the fossils of feathered dinosaurs," said Dr Chuong.
The research team located five genetic components that are required for the formation of feathers.
Scientists have tried to create alligators with feathers
plus the follicle that the quill originates from!

Figure 6. Hypothetical intermediate stage in the evolution of feathers from scales, with ‘cracks’ separating sections of a large scales into smaller, lateral plates, or protobarbs (From: Regal 1975).
But here we see a thecodont with the hypothesized structures.

Longisquama insignis was a thecodont. Those aren't feathers. They are very featherlike scales.
Thecodonts gave rise to the dinosaurs. One thecodont, Herrerasaurus, is so much like a dinosaur, it was originally thought to be a dinosaur.
So there's that.
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