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RE: Deinonychus claw use and origin of flapping



--
grr hotmail.
 
-------------------------------------- > Date: Fri, 16 Dec 2011 13:11:01 +1100 
> From: tijawi@gmail.com > To: dinosaur@usc.edu > Subject: Re: Deinonychus claw 
use and origin of flapping > > Anthony Docimo wrote: > > > Theropod backbones 
and joints lack > > even the most basic requirements for arboreality. > > > > 
Refrain: and yet they managed it in time. > > > Arboreal birds can fly. 
Therefore, they typically don't need to climb 
> up trunks or branches.
 
 which dodges the question of what they did before their family could fly.
 
this. > > > Those birds that climb trunks as adults (e.g., woodpeckers, > 
treecreepers) have special adaptations in the feet (and often the tail > as 
well) for trunk-climbing/trunk-clinging behavior. > > > >> This is why 
comparisons between theropods and mammals are so inapt - > >> including goats. 
The much-vaunted tree-climbing abilities of goats > 
>> are a partly a product of their heritage (placentals began as small > >> 
>> arboreal mammals) > >
 > > While theropods began as...? 
 
 > Terrestrial bipeds. > >
 
 > > (is the "crocodile-like beast with growing hind legs" theory still given 
 > > any weight?) 
 > Don't know what you're referring to here.
 
it's one of the earliest origin-of-dinosaur theories I ever heard of   (in both 
senses of "early")
 
 basically, dinosaurs evolved from something semi-aquatic like a croc, which 
grew longer and longer hind limbs (for swimming? i don't recall), until it was 
bipedal.
 
 
 > > > >> and partly a consequence of their current ecology > >> (negotiating 
 > > > >> steep and uneven terrain). > >
 > > Which we all know never existed in the Mesozoic. uh-huh. > >
 > Such terrains likely existed in the Mesozoic. We just don't know if
 > any theropod (or any dinosaur) was specialized for this terrain
 
 you don't have to be specialized for something  in order to deal with it.
 
 elephants can swim - that isn't because they're specialized for life in the 
water.
 
. > > > Oceans also existed in the Mesozoic. But we don't know of any marine 
> non-avian dinosaurs. Just because a particular environment existed
 > in the Mesozoic, doesn't mean a dinosaurian lineage was there to 
> exploit it. Dinosaurs weren't the only game in town.
 
very true.  also beside the point.
 
 dinosaurs dominated terrestrial niches throughout the Jurassic and Cretaceous 
and at least part of the Triassic.  just as pterosaurs ruled the Mesozoic skies 
(later time-sharing with birds), and just as marine reptiles ruled the seas, 
dinosaurs ruled the land.  and given that the ground is almost never smooth and 
uniformly even*, animals have developed the ability to handle themselves on 
uneven terrain.
 
unless you think the Yeti is a crocodile  --  same thing here, since just 
because mammals and birds rule the land now, doesn't mean that, if the Yeti 
exists, it has to be a member of either clade.
 
 
* = this is also an argument for why animals have never evolved wheeled 
movement.