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

Re: Microraptor hanqingi, new species from China.



On 5/25/2012 2:18 PM, Habib, Michael wrote:

Wouldn't the evidence in this case just be comparative studies of arboreal 
adaptations?

The statement made was that (paraphrasing) 'theropods w/ vertical climbing capacity must need special equipment to sit in trees' -- someone please support that idea!

It is critical to the argument that creatures evolving flight in tree-down mode would show "arboreal adaptations" that need comparing...

Do I need to point out (yet again) that if there is no *need* for special equipment, then there is no selective path to adaptation -- and thus "comparing [...] adaptations" is not useful in this context?

It is a simple matter of evolutionary theory, mechanical possibilities and uniformintarian assumptions -- either it reasonable to assume that a sleeping theropod would a) fall out of a tree and b) then be removed from the gene pool -- or it is a completely indefensible crock.

If it is a crock, then the argument that tree-down is falsified for (e.g.) Archeopteryx, due to it's toe angles, is also a crock.

Like Scott, I find your model of arboreal refugia quite reasonable.  I'm 
wondering, though, what testable predictions your model would make compared to, 
for example, a model that posits entirely terrestrial habits for paravians.  I 
think the roosting/resting concept has serious merit, but I'm not sure how to 
go about demonstrating it has serious merit more formally

"My model" falsifies the idea that an animal evolving flight in tree-down gliding-first mode will by evolutionary logic show "arboreal adaptations" in its skeleton -- beyond the basic capacity to climb a tree, that is...

This has implications to those who would, with any rigor, match speculations about the evolutionary path taken by birds as they achieved flight, and the evidence in the fossil record.

(thought experiments and scenario building are fun, but not terribly useful).

(Thought experiments are necessary, and highly useful. Ditto scenario building and ranking...)

Also, for all of the individuals in the current thread: we should be sure to 
give good cause at each step for putting paravians in trees to begin with.

Why? Is evolution no longer the null hypothesis?

Do we no longer assume, given deep time, and a diverse and numerous clade (Theropodia) -- 1) ghost lineages, 2) a reasonably complete array of ecologically viable lifestyles and 3) optimization to those lifestyles?

The potentially intuitive nature of arboreal proto-flight does not constitute 
good cause.

Huh?