The purpose of feathers

Aug 2013
956
Italy
Here's a thought-provoking question:

What was the original evolutionary purpose of feathers?

It seems certain that highly derived cynodonts as well as the earliest mammals were provided with fur in order to regulate their body temperature; but what was the case of the paravians and first true birds? Were the avialidae intended to fly from the very beginning, or did they sprout feathers ORIGINALLY only for the purpose of thermoregulation? Did feathered theropods and primitive birds learn, by pure chance, that flight was possible?
 

Corvidius

Ad Honorem
Jul 2017
3,047
Crows nest
Possibly sensory, like mammalian whiskers, then possibly became more spread over the body for display, and with the evolutionary progress to endothermy in the archosaurs that became pterosaurs and dinosaurs, they became insulation and display. A sensory beginning is I think rather tenuous and probably impossible to prove either way, but looking at how important modern feathers are to birds for display, and how important colourful display is to some modern lizards, I would think the origin is in display, then insulation. On this I'm presuming that pterosaur pycnofibers share the same origin as dinosaur protofeathers, but stopped further development at a very early stage.

The co-option of feathers for flight is the result of a number of adaptations in various theropods for purposes nothing to do with flight, insulation, display, nest brooding. I would guess that those theropods that first jumped out of a tree, then just by luck found that if they spread their long arms they parachuted down to the ground and survived, gliding and flapping flight then followed, but it was not pre-ordained, just natural selection and serendipity. Simplistic I know, but without a time machine we can only guess.
 

sparky

Ad Honorem
Jan 2017
5,180
Sydney
.
I quite like the brooding function , feathers have superb thermal insulation
altogether this is impossible to prove ,
evolution has a sneaky way of doing several things at once , all of them by "accident"
 
Aug 2013
956
Italy
Possibly sensory, like mammalian whiskers, then possibly became more spread over the body for display, and with the evolutionary progress to endothermy in the archosaurs that became pterosaurs and dinosaurs, they became insulation and display. A sensory beginning is I think rather tenuous and probably impossible to prove either way, but looking at how important modern feathers are to birds for display, and how important colourful display is to some modern lizards, I would think the origin is in display, then insulation. On this I'm presuming that pterosaur pycnofibers share the same origin as dinosaur protofeathers, but stopped further development at a very early stage.

The co-option of feathers for flight is the result of a number of adaptations in various theropods for purposes nothing to do with flight, insulation, display, nest brooding. I would guess that those theropods that first jumped out of a tree, then just by luck found that if they spread their long arms they parachuted down to the ground and survived, gliding and flapping flight then followed, but it was not pre-ordained, just natural selection and serendipity. Simplistic I know, but without a time machine we can only guess.
Once again, Corvidius, you've provided me with lots of intriguing ideas to think about. I had never thought about the sensory aspect, but it is a viable possibility. So, too, is display, especially if the males' feathers were brightly coloured (I wonder if the female paravians, like many species of modern birds, would have had plumage of duller colours).

Yet somewhere in the back of my mind lurks the suspicion that Mother Nature, in her inscrutable wisdom, really DID pre-ordain the flight of birds; the earliest ones were, in general, very small fragile creatures, and so the evolutionary process would have given them the advantage of being able to escape from predators by means of flight. This process would have begun with the feathered dinosaurs (most of which were, at best, gliders, not perfectly adapted for flight) but would have progressed rapidly until genuine birds, capable of sustained flight, appeared.

What do you think?
 

sparky

Ad Honorem
Jan 2017
5,180
Sydney
.
that's all very well but bring the question of Nature per-ordering bats to fly !
or dinosaurs to outmatch sharks to swim , some species flew very well without any feathers
as for display , bodily appendages and colored skin can do that very well too
there is little evidence on the dinosaurs pigmentation , the classic representation of monotone grey or brown is probably too simple
 

Bart Dale

Ad Honorem
Dec 2009
7,095
Possibly sensory, like mammalian whiskers, then possibly became more spread over the body for display, and with the evolutionary progress to endothermy in the archosaurs that became pterosaurs and dinosaurs, they became insulation and display. A sensory beginning is I think rather tenuous and probably impossible to prove either way, but looking at how important modern feathers are to birds for display, and how important colourful display is to some modern lizards, I would think the origin is in display, then insulation. On this I'm presuming that pterosaur pycnofibers share the same origin as dinosaur protofeathers, but stopped further development at a very early stage.

The co-option of feathers for flight is the result of a number of adaptations in various theropods for purposes nothing to do with flight, insulation, display, nest brooding. I would guess that those theropods that first jumped out of a tree, then just by luck found that if they spread their long arms they parachuted down to the ground and survived, gliding and flapping flight then followed, but it was not pre-ordained, just natural selection and serendipity. Simplistic I know, but without a time machine we can only guess.
I agree with you. The advangtage of a display origin of feathers is that you don't need to cover hardly any of the body to be useful. Unless the feathers could covef a significant fraction of the body, they would be of that much help for insulation. Even a few feathers would still work as a display mechanism.