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Re: Microraptor also ate fish

> I doubt if we would find taxa that are arboreal (sensu
> stricto) that
> lack arboreal characters.

This may be the crucial point.

Arboreality (cursoriality, fossoriality...) may not be *provable* from the 
fossil record.

But it can be falsified.

And Microraptor (or Archie for that matter), while exapted for arboreality, 
were not adapted to it. Their "para-arboreal" (arboreal sensu lato) traits 
worked as well or better with a mainly cursorial lifestyle that could utilize 
slight elevations (a meter or so above the surrounding terrain) to get the 
critters above ground-effect heigth, vastly increasing the distance traveled 

Confuciusornis seems to me a more intriguing case.

Yet we must not forget that what was an arboreal adaptation in the Aptian may 
not be one today. The arboreal niche was still developing; it was still new 
enough to be almost devoid of competitors.

To argue that something lived in trees is not necesarily very informative by 
itself; "What trees? and what else lived up there?" may be more interesting to 
ask, particularly when dealing with exaptations or otherwise incipient traits.

Compare: Late Carboniferous temnospondyls were not very convincing as 
(semi)terrestrial apex predators by today's standards. But if you take the 
whole ecosystem into account, quite a lot of them seem to have been just that.