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Re: Arboreal Dinosaurs

BHR (probably someone connected to Gary Riegler) wrote:

>                              ...I've seen numerous restorations of
>small theropods and ornithopods in trees(ornitholestes &
>hypsilophodon,etc...). I don't know if this has already been discussed
>or is a settled issue...

Oh, it's been discussed alright.  Which theropods climbed trees is far from 
settled.  The extreme cases would be Tyrannosaurus (climbing practically 
impossible) and Archaeopteryx (climbing very likely).  The chances of any 
particular dinosaur climbing depend on its weight and the length and strength 
of its forelimbs.  Claws are also useful, but I can't think of any theropod 
deficient on that score.  IMO, the small long-armed theropods such as 
Velociraptor and Ornitholestes are plausible climbers.

The leading theory on the origin of bird flight is that an arboreal ancestor 
began by jumping between branches, then developed a lifting surface to glide 
(like certain squirrels, frogs, snakes, lizards and marsupials).  The final 
step was evolving a way to flap this wing.  And of course the leading theory on 
the origin of birds themselves is that they are theropods.

As for Hypsilophodon, this was originally reconstructed/restored with one toe 
pointing backwards, as in perching birds.  This led to the suggestion that it 
climbed trees.  That anatomical idea is now considered incorrect, and 
Hypsilophodon is not likely to be a climber (mainly because it's too big).

                                                All the best,

                                                                Bill Adlam