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Re: Velociraptor profiles and a little background



Bye the way, sorry for the multiple posts regarding my request. Outlook
flunked up and sended an e-mail that was work in progress to the list for
unknown reasons.


David wrote:

>_All_ dinosaurs couldn't swim? While almost all living vertebrates can?
>Strange, strange...
>
Alright, name some swimming reptiles that do not have any specialized
characters, therefore eliminating the Iguana's from the Galapagos-islands.
Dinosaurs are advanced reptiles, but none of the theropod genera show any
signs of a water based or near water based life, like a specially adapted
tail. Occasional swimming, as envisaged by HP G.S. Paul in his magnificent
drawing of Allosaurus chasing an Apatosaurus into the water, is certainly
possible, but what you are implying is constant activity in the water.
That's what I have a problem with.


>Why lift? With all these air sacs, the animal produces already more than
>enough lift and has to care about how to stay down. Beating wings
underwater produces thrust. Lots of living birds do this.

Has this been proven by testing or do you just or everyone assume this is
how it works? And if so, could you please give me the ref.

>> From the point that an animal starts with swimming, look at whales
>> and manatees,
>
>They aren't _starting_ to swim. They have become _exclusively aquatic_.
Look >at otters. Oh, er, and penguins. :-)

But before that they had to move trough a fase when they are learning to
swim, it's not like in a magical evolutionary clap in the hands or three
clicks with your red heels evolution moves. But this is a basic fact, not
worth of repeating it all over again.

>You do know what otters do? You do know what _all birds I know of_ do, even
>those that never come close to water except rain? They impregnate their
>body coverings with oily secretions. (Galliformes have reduced that gland
on the
>tail, but they still have it.)

Of course I know what otters do, they swim on their backs, cracking shells
open with rocks. :) But you are saying that that oil secretion is what is
helping those birds to swim, it had to have evolved. The current theory
regarding the origin of feathers is that is was meant to trap body heat,
since dinosaurs, at least the theropods were warm-blooded. It is not the
current concensus feathers evolved to make the dinosaur swim (although it
could be a speculative possibility), so the feature had to evolve from
ordinary feathers we all see in present day birds. Well, kinda at least...
Just imagine this for moment: a poor lonesome Sinornithosaurus, let's call
it "Dave" for the time being, is checking out a small lake and sees all
these fish in it. He's hungry as hell and willing to eat anything, he
decides to go for it and plunges itself in the water. Poor "Dave" drowned
since his feathers are not equiped with the oily secretion. Almost seems
like Mesozoic "Jackass" :)

>1. Usually they don't get wet. I've seen lots of feathers lying on water as
>if the water were solid. Most diving birds stay completely dry.

And again you are implying the oily secretion was immediatly present in
theropod dinosaurs, which hardly seems possible. It takes time to evolve
such a feature.


Rutger Jansma