This makes me question the need for cooling structures on ancient life so I'll get right to the point.
Did the hollow flight feather evolve from something that was originally meant to act as a blood filled radiator?
Some back ground and the idea in question.
There are many wierd shapes of dinosaurs, There are some with massive plates or spines or other protrusions that stick out from there body. Some such as the staggesaurous I'm going to assume have vascualr plates designed for heating in the sun and cooling in the shade. If they were spacifically for heating these creatures would have had problems at night so I'm going to assume cooling. These dinos didn't have feathers because they used plates. Some of the four legged dinosaurs had sails on their backs such as Dimetrodon. By the way spiney back sails can be aligned with the sun to avoid head accumulation due to a smaller surface area to be heated and thus still provide cooling in direct sunlight. Certain theropods such as spinosaurous maintained their lizard heritage by using extreme body protrusions for regulating heating and cooling. Basically this idea holds that a spinosaurous maintained it's body temperatures with a combination of water and it's huge spiny back sail. The reason it had a huge spiney back sail is because it was actually still a lizard.
This is where the feathers come in.
For Theropads without huge spiney protrusions to be able to grow in size and still chase prey without overheating, they needed another way too cool, and this is where 'flight feathers' started to evolve.
Basically flight feathers on modern birds are hollow but do not grow in this way at first.
At first they are filled with blood proving that feathers, even on modern birds can be filled with blood.
They are called pin, or blood feathers.
So what if the hollow effect wasn't evolved yet on dinosaurs and earlier in their evolution, feathers filled and stayed filled with blood?
This would allow a dinosaur to use them as a radiator while running and chasing prey by spreading them out while cutting off the cooling effect by hugging them into the body.
The little arms on the large theropods were designed to both expand and contract the blood feathers lto control the effect.
The idea here is that Dinosaurs had an early blood feather version of flight feathers used primarily for cooling while hunting that evolved into flight feathers as the earth cooled a few degrees.
When chasing prey, ancient theropods would expand their wings and adjust their tails to best cool off while chasing prey.
Sweat would come out of the pours and run along the feathers.
There's a chance that many of the large theropods such as T-Rex overheated their prey!
The earliest use that dinosaurs probably had for flight feathers as an aerodynamic force was to improved stability, acceleration, cornering and in general land based agility including dropping from trees for hunting purposes.
Flight probably evovled from 'tree droppers' with 'accelerator and cornerers' becoming birds such as ostrich and emu.
Land birds never lost their ability to fly as flying was never an original ability of feathered animals.
Ever notice an Ostrich flares it's feathers out when it runs?
Watch this video and notice that the Osterich flares it's white wings out when it runs that you can't see when it stands still or walks. It's literally running like an ancient theropod would have flaring it's wings for the cooling effect to prevent heat stroke from running.
The ostriches in this video look like they're cupping air in their 'wing pits' to keep cool while running. An effect left over from hotter times.
In the grand scheem of feathers I'm assuming there are downy type insulation feathers and hollow (blood filled) cooling type feathers which evolved into insulation flight feathers with global cooling to become flight feathers.
So in other words Ancient theropods used solid downy feathers for warmth but also used blood feathers as a radiator for running down prey in a hot environment which then became the flight feathers of todays colder climate birds.
Edited by RandomJay, 25 March 2014 - 12:28 AM.