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

RE: COMPETING BATS, BIRDS & PTEROSAURS



-----Oorspronkelijk bericht-----
Van: Henri Rönkkö [mailto:henri.ronkko@kolumbus.fi]
Verzonden: dinsdag 27 februari 2001 21:42
Aan: dinosaur@usc.edu
CC: darren.naish@port.ac.uk
Onderwerp: COMPETING BATS, BIRDS & PTEROSAURS

>I believe birds do better than bats in daylight because birds rely on
>vision whereas bats rely on echolocation. Echolocation is neither as
>acute nor as effective as seeing, if one has good eyes. Birds certainly
>have very good eyes. However, in darkness, where nothing can be seen,
>echolocation is better than eyesight, so the bats have managed to fill
>the nocturnal niches.

Maybe in reality that's the other way around? Birds already existed (let's
assume that bats evolved later than birds even thought that's probably far
from 100% certain) and already had good eyesight so they primarily dominated
the day time. Bats had to try and do their stuff at night to avoid direct
competition with the ever present bird during the day. This in turn was a
strong selective pressure that caused the bats to quickly "develop"
echolocation.

Chicken and egg situation? Personally, the "forced in the dark ->
echolocation" seems a bit more probably to me than "echolocation -> better
suited for the dark". But of course that's no more than a hunch.

Met vriendelijke groeten,
Jarno Peschier (postbus@jarno.demon.nl via jpeschier@impuls-sw.nl)