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Re: flapping from gliding
Arboreal gliding faunas:
(two distinct radiations)
(two, maybe three separate evolutions)
( the agamid _Draco_ and Kuhl's gecko).
( I only know of one- more a parachuter, really)
(sifakas or sakis or whatever)
*(we can't be sure, but it would seem likely- they're
rather poor runners, after all)
That thing with the big scales on it's back George talks about a
lot and I can't remember the name of. (extinct)
Creatures that specialize in leaping after insects or other flying
animals (If this were actually a viable niche, you'd expect at
least one group -the frogs- to fill it), creaturesthat run around using
limbs and tail as airbrakes:
extant: ??? extinct: ???
Arboreal gliders: ~15 , insectivorous leapers/aerobatic
Gliding is a VERY common adaptation. Most branches of the
amniotes except turtles (for obvious reasons) fill it: placentals,
marsupials, squamates (lizards and snakes), amphibians. And if there
aren't gliding newts it's just because they probably don't spend a
lot of time in trees. Not to mention a truly impressive record of extinct
The arboreal hypothesis has two main strengths. a) the leap between
gliding flight->powered flight seems to me to be, both conceptually and
evolutionarily, an easier one, than the one between a running or leaping
predator and powered flight.
b)It's based on evidence obtained by looking at both fossil and extant
life forms and looking at the real world. We know today that carnivores
routinely go into the trees: pine martens, racoons, red pandas (carnivora
if not a carnivore) cats, grey foxes, young Komodo dragons, etc. We don't
know of ANY predators that spend much of their time pursuing the prey in
other ways hypothesized.
I think if there's any reason we are so taken with
ground-up theories, it's because we're ground living ourselves and that's
how we ourselves did it.