Re: Cold Blooded Dinosaurs

On Mar 8, 1:07 am, "JTEM" <jte...@xxxxxxxxx> wrote:
"Ken Shackleton" <ken.shackle...@xxxxxxx> wrote:
"JTEM" <jte...@xxxxxxxxx> wrote:

"Ken Shackleton" <ken.shackle...@xxxxxxx> wrote:
How about this then.....how many [living] ectothermic
animals can you name that have body coverings that
are used as insulation?

So you're saying that it's an instant thing? Maybe a
package deal? Feathers & endothermy appeared exactly
the same time?

This is a typical example of how you deal with things
head-on. I simply asked a question...thanks for the
non-response.

It's like this.

You failed to answer the question....


At some point the mammal line became
warm blooded. At some point the bird line became warm
blooded. Now there's a number possibilities here. One
is that body coverings followed (came after) the
evolutionary development of endothermy. The other is
that body coverings preceded the evolutionary
development of endothermy.

The least likely possibility is that the developed at
the exact same time.

In your opinion perhaps. Perhaps the insulation co-evolved with
endothermy, as John has suggested. Without any insulation, regulating
your temperature is very difficult [read as energy expensive]. It is
almost certain that endothermy first occured over 200 million years
ago [with the appearance of the first mammals]....so, if endothermy
took [say...] 5 million years to co-evolve with body coverings, it
would seem like an instantaneous flash in the fossil record.


Now, as I pointed out, endothermic animals do not
require body coverings.

Very special cases only.

All birds seem to, and the only mammals without some sort of
insulation are large and/or live in the tropics; or can control the
temperature of their environment.

We know this for a fact,
because a number of mammal species are in fact bald.

Some of the bald ones have insulating blubber...so you can't count
those in your list.

Another thing I pointed out is that there's no bird
species which are bald. What this does is suggest that
body coverings in birds serve a function that is even
more important than insulation.

The ONLY model we have to go by tells us that being
warm blooded does not require body coverings.

It does require being able to maintain a stable body temperature,
that's all really. Animals that are ectothermic would be at a
disadvantage with insulation, since it would take more time to warm up
as well as cool down. I think that this is why we do not see ANY
ectothermic animals with thermal insulation. It is also true that ANY
animal that has thermal insulation IS endothermic....and this is why
it's a safe bet to assume that ANY fossil that has indications of
insulating body coverings would also be endothermic.

That,
given enough species and enough environments a warm
blooded animal will lose its body covering.

Nonsense....unless there is a special need to lose the
coverings.....they do not lose them. Every bald mammal species alive
today had furry, endothermic ancestors....and they lost their body
coverings for one of two reasons:

1. The problem of losing heat became greater than the need to retain
it.
2. The environment favoured baldness and the animals found another way
to retain heat [such as with blubber in whales, or living in a
controlled environment like the mole rat].


Birds do
not.

Birds maintain a higher temperature than mammals, and they have a much
greater surface area to mass ratio than most mammals...so will lose
heat much faster than your typical mammal. Insulation is vital to
birds.


Something which is even MORE SIGNIFICANT than insulation
is keeping birds covered.

Flight? The insulation must not only be effective in birds, it must be
light-weight to allow flight. Birds that fly cannot afford the weight
of blubber, so they must depend on feathers to keep warm.

This is what the evidence, the
only model we have to go by, suggests. And if something
even more important than insulation exists, we can't rule
out that it -- and not insulation -- was the catalyst for
the development of feathers.

Pure bullshit once again. Once again, you believe that your
interpretation of the evidence is the only possible scenario...and you
hide behind the claim of only presenting facts rather than
conclusions.


.

Relevant Pages

  • Re: Cold Blooded Dinosaurs
    ... should I point out that "Insulation" ... are mammals without body coverings. ... So....if feathers evolved to support endothermy, ... reason why there *needs* to be any bald mammals. ...
    (talk.origins)
  • Re: Cold Blooded Dinosaurs
    ... is that body coverings followed the ... evolutionary development of endothermy. ... body coverings in birds serve a function that is even ... more important than insulation. ...
    (talk.origins)
  • Re: Cold Blooded Dinosaurs
    ... is that body coverings followed the ... evolutionary development of endothermy. ... body coverings in birds serve a function that is even ... more important than insulation. ...
    (talk.origins)
  • Re: Cold Blooded Dinosaurs
    ... That insulating coverings and endothermy go hand-in-hand. ... case endotherms today do not use insulation, ... overheat a lot quicker. ... So a little body covering ...
    (talk.origins)
  • Re: selection criteria for obesity
    ... > some reason) and needed some compensating insulation. ... than fur. ... animals in Africa, including chimps. ... infant on such ground. ...
    (sci.anthropology.paleo)