Answering any questions on Evolution

[Wiccan_Child]

So do you know which species evolved them first?

No, partly because 'feather' is ultimately a broad structure, and how broad is a matter of definition. We can narrow down where on the evolutionary tree feathers originated, though - that's how we know, for instance, that it's in Reptilia, and then in Dinosauria, etc.

I'm guessing they were reptilian since: Archaeopteryx has more in common with other small Mesozoic dinosaurs than it does with modern birds. Wikipedia.

Many dinosaurs had feathers, including Velociraptor. So yes, the origin of feathers lies well within Dinosauria.

which leads me to another question. were dinosaurs warm blooded or cold blooded?

A good question. The 'heat' of your blood refers to a complex interaction of physiological features that control your body's temperature. Reptiles heat or cool their body using the Sun and the shade, because they can't maintain their own temperature, meaning they're cold blooded. Mammals, by contrast, can manipulate their metabolism to heat up or cool down - we don't need to run for shade if we get too hot - we can just sweat.

Anyway. What about dinosaurs? Are they cold blooded? Well, though the prevailing theory is that they're cold blooded, only a few days ago a new study put that into doubt.

 

[Naraoia]

so who did it inherit them from and how were they co-opted into something they were not original intended for?

Feathers proper, Archie inherited from its dinosaurian ancestors. The consensus now is that all coelurosaurian dinosaurs - that includes T. rex and its kin, Oviraptor and relatives, the ostrich dinosaurs, "raptors", and lots of weird birdlike critters - had at least simple, unbranched protofeathers. Many of them also had true, vaned feathers. Members of all of these major groups have been found with fossil feathers.

Then we have a gap in the evidence - no feather fossils for other theropods, though I think scale impressions have been preserved in several species. (However, IIRC scale impressions are also known from tyrannosaurs, but we know that some members of that group were fully feathered - so scales from one part of the body are not good evidence against feathers.)

However, bristle- quill- or fur-like body coverings are known from not just the closest relatives of birds, but from very distantly related dinosaurs, too. (Tianyulong is a recent example.) What's more, dinosaurs' flying cousins the pterosaurs were covered in fur-like stuff palaeontologists affectionately call "pterofuzz". So there is a hypothesis that all of these structures - pterofuzz, feathers and bristles/quills etc. in various kinds of dinosaurs all come from a common ancestor. It's hard to test this hypothesis as of yet, since it would require either a detailed comparison of the known bristle/feather type things or fossils connecting the different occurrences. It's interesting nonetheless.

So do you know which species evolved them first? I'm guessing they were reptilian since: Archaeopteryx has more in common with other small Mesozoic dinosaurs than it does with modern birds. Wikipedia.
which leads me to another question. were dinosaurs warm blooded or cold blooded?

I think they've overwhelmingly been considered at least somewhat warm-blooded in recent years. Many of them were feathered, grew pretty fast, lived in cold climates, and they did beget birds after all. Being warm- or cold-blooded is not an either-or property. Animals have various ways of regulating their temperatures from the inside, and some of them do so only some of the time. For example, bees can work their flight muscles without actually flying to warm up on cold mornings, and there are mammals who bask in the sun to reach their working temperatures.

Anyway. What about dinosaurs? Are they cold blooded? Well, though the prevailing theory is that they're cold blooded, only a few days ago a new study put that into doubt.

My impression was that this hasn't been the prevailing theory in a long time.