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Re: Arboreal Theropods: The prize at the bottom of the cracker jack box



Gesendet: Freitag, 19. Juli 2013 um 05:53 Uhr
Von: "Tim Williams" <tijawi@gmail.com>

> Feduccia (among others) has argued that the juvenile hoatzin serves as
> an analog for quad climbing in _Archaeopteryx_. I think it's a crock.
> The hoatzin has a specialized grasping foot with a massive hindtoe
> (not surprising, because it's an arboreal bird!). In juveniles, these
> feet are huge in proportion to the rest of the body. Although the
> short stumpy wings are equipped with claws, the feet are actually
> majorly responsible for climbing.

And much of the rest is done by the beak. Archie using its delicate jaws and 
tiny teeth for that purpose strikes me as unlikely.

> > Those who persist in saying that they get to decide when reversed halluces 
> > must evolve are looking the wrong
> > way through the telescope - back from a world where it has already evolved, 
> > and biased by that historical
> > contingency. All historical events seem inevitable AFTER that fact, just 
> > look at the last American election
> > and, after election night, how many people suddenly knew it all along!

That's a really bizarre example to choose. I happened to be in the US during 
election night, watched the coverage, and the one and only thing I was 
surprised about is the amount of denial Romney in particular and his campaign 
in general were in -- both during much of the campaign and on election night. I 
seriously wonder if Romney believed in the "White Horse" prophecy, which I 
won't expound on here.

> The pre-election polls were pretty consistent in predicting an Obama
> victory.

Understatement.

> A great many people did know it all along, because they
> understood the polling data. (Check out Nate Silver's blog, 538, as
> an example.)

Another example is http://www.electoral-vote.com/ -- different and less math, 
same predictions.

> I'm intrigued why the hyperelongated finger of _Epidendrosaurus_ is an
> arboreal feature.

Indirectly, via *Daubentonia*, *Dactylopsila*, and the apatemyids. The gnawing 
teeth fit this, as may the descended hallux.

> >>So unless one has a compelling reason to put
> >>non-avialan theropods in trees, why do it?
> >
> > As Orenstein mentioned -- PREDATOR AVOIDANCE.
>
> I originally meant "compelling" from a morphological perspective. But
> since you mention "predator avoidance", yes this does sound like a
> good reason for driving a small theropod up a tree. (Hoping, of
> course, there aren't larger predatory arboreal mammals already in the
> tree.)

On that latter point... *Henkelotherium* was small... I don't remember the size 
of *Volaticotherium*... apart from *V.*, the triconodonts were all terrestrial, 
it seems... so was *Zhangheotherium*, IIRC...

But what about the squamates? The type specimen of *Xianglong* 
http://www.pnas.org/content/104/13/5507.full was rather small, but it hadn't 
even ossified its carpals and most of its tarsals yet, so it would have grown 
quite a bit larger.