Evolution of feathers

[Capt. Ridley's Shooting Party]

I'm basing this thread off this website: http://users.aber.ac.uk/rdd1/Biologybit.htm

The site notes that the earliest creatures which had wings had feathers. It also notes that the "birds" couldn't fly. Now, the site also lists several other uses for feathers, besides flight, but something bothers me.

The advantages listed apply to every animal, apart from flight, yet we don't see any other animals (unless I'm right in thinking the platypus has feathers) with feathers, which would kind of imply that the use of feathers is mainly for flight. Yet we come back to the first featehred creatures who couldn't fly. ???

What's the latest thinking on the evolution of feathers? Why are they not more common amongst other animals?

[Markxxx]

The Science Channel (From Discovery usually on Digital Cable) just ran a special on the evolution of feathers.

According to this recent fossil finds in China indicate that many dinosaurs (the kind that T-Rex belonged to) actually had feathers.

They said the first feathers were used for warmth only. Birds later adapted them for flight.

They said Archeoptrex(sp?) clearly had feathers used for flight. Though Arche...was a bird, they also found older dinasours with feathers used for warmth. Then in China they found a dinasour with BOTH types of feathers warmth AND flight.

The platypus is a mammal. Not much of one but a mammal none the less.

Remember evolution doesn't do what's best, it does whatever works for reproduction.

Fur works for warmth just as well as feathers. So both are used.

Flight has appeared to evolve in Birds, Mammals, Pterasaurs AND insects. They all evolved independently of each other.

Since virtually all warm-blooded animals are Mammals or Birds, fur and feathers explain why they didn't evolve elsewhere. (OK also blubber helps as well)

Think of it this way if you have a Mink coat it keeps you warm. But if I have a synthetic coat it keeps me warm. But that doesn't mean I have to run out an get a mink.

[Chronos]

If I'm understanding the OP correctly, we have this sequence of events:

1: Some critter A evolved feathers, which at this stage serve no purpose other than keeping warm.

2: Some other critter B, descended from A, evolved the trick of using these feathers, along with modified forelimbs and other adaptations, for flight.

3: All descendents of critter A which are not descended from critter B died out, while some things descended from B did survive.

I think that +MDI is asking why step 3 occured. Certainly, there is a niche for "insulated non-flying critter", since all mammals and some birds (decended from critter B, who flew) match that description. So why aren't there any feathered critters left from the portion of the lineage that never developed flight?

[David Simmons]

Originally Posted by Markxxx

Fur works for warmth just as well as feathers. So both are used.

According to our friend Isaac Asimov in an essay whose name I forget, feathers are better than fur as insulation. And this reinforces you point about evolution not resulting in the "best" solution. Since fur is good enough it persists even though there is a "better" solution.

[Cuckoorex]

Originally Posted by Chronos

So why aren't there any feathered critters left from the portion of the lineage that never developed flight?

That would be the age-old question (modified for specificity), why did the non-avian dinosaurs die out?

On the other hand, we do have several flightless birds in the fossil record and today we have ostriches, emus, kiwis, penguins, auks, puffins, etc.

[David Simmons]

Originally Posted by Cuckoorex

That would be the age-old question (modified for specificity), why did the non-avian dinosaurs die out?

On the other hand, we do have several flightless birds in the fossil record and today we have ostriches, emus, kiwis, penguins, auks, puffins, etc.

And although they fly well, coots seem to do so only to escape imminent death.

[Darwin's Finch]

Originally Posted by +MDI

What's the latest thinking on the evolution of feathers? Why are they not more common amongst other animals?

The latest thinking is, simply put, that feathers predate, or, at the very least are not unique to, birds. Critters like Archaeopteryx have been classified as "undeniably birdy" in form, and until relatively recently, were the earliest known critters to have feathers. Thus, it was believed for some time that feathers are a synapomorphy (shared derived character, or a trait that is particular to a given group) for birds.

However, recent finds in China have shown that such is not the case. Markxxx mentioned a special shown on the Science Channel; one of the specific critters which were highlighted in that show, and which demonstrates that feathers pretty unambiguously evolved in non-flying dinosaurs, was Sinosauropteryx, which was definitely a dinosaur (it looked much like Compsagnathus, only the latter has never been found with feathers). A couple other specimens, for which there is some debate as to whether they are avian or non-avian dinosaurs, Caudipteryx and Protoarchaeopteryx, also show evidence of feather (or proto-feather) impressions.

If, as the evidence seems to show, feathers did, indeed, evolve in non-flight capable animals, then it would seem reasonable to conclude that insulation is the likely "reason" for their evolution. As for why they do not appear in other animals, it's a matter of phylogeny. Feathers evolved only in a specific lineage, the only survivors of which are birds. The precursors for feathers have not arisen in any other lineage, thus, no feathers.

[DanBlather]

The non-flying, feathered animals died out because they were eaten by the non-flying, furry animals: mammals. A recent case of this is the Dodo bird which quickly died out when mammals invaded their island.

[Cuckoorex]

Originally Posted by DanBlather

The non-flying, feathered animals died out because they were eaten by the non-flying, furry animals: mammals. A recent case of this is the Dodo bird which quickly died out when mammals invaded their island.

Somehow I doubt that explanation covers it, considering the non-avian dinosaurs were reasonably safe from predation by the mammals that they shared the environment with.

[lissener]

They've already been brought up in this thread, but I think the OP is roundly answered by mentioning such animals as Kiwis and Penguins: animals who use feathers strictly for insulation, not for flight.

[Floater]

Originally Posted by Cuckoorex

On the other hand, we do have several flightless birds in the fossil record and today we have ostriches, emus, kiwis, penguins, auks, puffins, etc.

Auks, including puffins, are quite good at flying.

[Chronos]

They've already been brought up in this thread, but I think the OP is roundly answered by mentioning such animals as Kiwis and Penguins: animals who use feathers strictly for insulation, not for flight.

Not answered, because while penguins, ostriches, dodos, etc. cannot fly, they did evolve from other creatures which could fly. The question is concerning those creatures which did not evolve from flying creatures, but which did have feathers.

[Cuckoorex]

Originally Posted by Floater

Auks, including puffins, are quite good at flying.

Oops.