There is no other choice. The problem touches on a greater puzzle of the origin of avian flight. You positioned yourself in the arboreal camp: the flight originating as gliding. But there is another equally strong school of thought: that the flight originated on the ground and it was powered flight from the onset. Gliding is not controlled, so it is hard to explain the switch to endothermy. Feathers are not needed for efficient gliding (as suggested by many an extinct and living gliders), actually, feathers make it harder to glide in a canopy of a tree. A lot of arguments of the off-the-ground theorists make good sense.
What you see in that paper is the echo of this long and undetermined battle. You are also too hasty to assume that feathers are modified scales. There are theories that feathers (like hair in synapsids?) first grew between the scales as tactile appendages and then gradually replaced the scales. To make the story short, it is not clear what was the correct sequence of events (feather, flight, endothermy), what was the degree of evolutionary convergence, and what was the nature of avian ancestors. As I told you elsewhere, the closer you get to the issue the more murky it becomes. It looks simple and straightforward only from afar and only when the problem has been solved.
"But there is another equally strong school of thought: that the flight originated on the ground and it was powered flight from the onset."
Does it matter?
"Gliding is not controlled, " Not WELL controlled and only in the beggining. Flying Pterosauria could control their flight more or less, though coud not fly from the ground.
"Feathers are not needed for efficient gliding (as suggested by many an extinct and living gliders)"
They become effecient when reptilias switched from simple gliding to controlled gliding (which was semiflying). They could make animals lighter and feather-like scales at margins could add the additional size to the wing without gaing weight. Why not?
"There are theories that feathers (like hair in synapsids?) first grew between the scales as tactile appendages and then gradually replaced the scales."
Maybe. Anyway feathers or scales - both are skin derivates, so it does not matter much.
"it is not clear what was the correct sequence of events (feather, flight, endothermy), what was the degree of evolutionary convergence, and what was the nature of avian ancestors. As I told you elsewhere, the closer you get to the issue the more murky it becomes."
Agree, but it is difficult or iven impossible to restore all detailes now. Though it would be very interesting to know about new ideas progressing. Thank you!
What you see in that paper is the echo of this long and undetermined battle. You are also too hasty to assume that feathers are modified scales. There are theories that feathers (like hair in synapsids?) first grew between the scales as tactile appendages and then gradually replaced the scales. To make the story short, it is not clear what was the correct sequence of events (feather, flight, endothermy), what was the degree of evolutionary convergence, and what was the nature of avian ancestors. As I told you elsewhere, the closer you get to the issue the more murky it becomes. It looks simple and straightforward only from afar and only when the problem has been solved.
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Does it matter?
"Gliding is not controlled, "
Not WELL controlled and only in the beggining. Flying Pterosauria could control their flight more or less, though coud not fly from the ground.
"Feathers are not needed for efficient gliding (as suggested by many an extinct and living gliders)"
They become effecient when reptilias switched from simple gliding to controlled gliding (which was semiflying). They could make animals lighter and feather-like scales at margins could add the additional size to the wing without gaing weight. Why not?
"There are theories that feathers (like hair in synapsids?) first grew between the scales as tactile appendages and then gradually replaced the scales."
Maybe. Anyway feathers or scales - both are skin derivates, so it does not matter much.
"it is not clear what was the correct sequence of events (feather, flight, endothermy), what was the degree of evolutionary convergence, and what was the nature of avian ancestors. As I told you elsewhere, the closer you get to the issue the more murky it becomes."
Agree, but it is difficult or iven impossible to restore all detailes now. Though it would be very interesting to know about new ideas progressing. Thank you!
Reply
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