[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Campbell's even crazier than a MANIAC? (archeopteryx climbing)



--- On Fri, 9/26/08, David Marjanovic <david.marjanovic@gmx.at> wrote:
> > Also worth noting is anything capable of powered
> flight, is capable of 
> > gliding flight.

> > So I find the concept of a powered flight ability
> before a gliding ability 
> > as some proposed completely false soaring should be
> differentiated from 
> > gliding).
> > Its either powered flight in tandem with gliding, or
> gliding, then powered 
> > flight later.
> 
> I don't see how this follows.
If it can fly... it can glide - aside from direct thrust flight (rockets, VToL 
jets). I don't think the ability to fly powered could have possibly come before 
the *ability* to glide (that isn't to say they would routinely stop flapping 
midflight)

> > I think its highly likely powered flight did not come
> before soaring.
> 
> The fossil record points in the opposite direction: the
> bats still haven't 
> got the idea of soaring, and the birds seem to only have
> evolved it after 
> the Mesozoic was over. Even the pterosaurs started with
> small forms that 
> didn't have particularly long wings.

Well, we don't know if bats ever did soar at any point in the past, and I am 
specifically implying ridge soaring, not using thermals.
Also, given that bats are nocturnal, and winds  generally calm down during the 
night, that may make an early ridge soaring phase less likely.
Also, given they are insectivores, flying insects are not likely to be found 
lingering in the lift band of a ridge with a significant wind.

Mechanically speaking, ridge soaring would probably provide the lowest barrier 
to flying to a gliding creature poorly adapted for flight.

I guess I'll conceed Bats probably flapped before soaring (if they ever 
do/did), but I still think ridge soaring was probably one of the first niches a 
ptero or dinobird occupied once it had wings giving it any kind of gliding 
ability, before the wings and muscles were large enough for powered flight.