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Re: Microraptor also ate fish
It was my hypothesis, so I'll answer.
Observing the behavior of basal birds, and citing Glenn and Bennet (2007)
and Birn-Jeffery et al. 2012, I proposed that Microraptor may have foraged
and nested on the ground and roosted and/or brooded chicks in trees, as do
tinamous, galliforms, and some anatids today. Of course a detailed study
of the pes of Microraptor could turn up evidence, say reduced flexor
tubercles or reduced ranges of motion in the joints, that were significant
even controlling for body mass, that could falsify the hypothesis. The
hypothesis could be supported by finding morphological correlates for
gripping, perching, or roosting.
Thus I would not say I am 'trying to put Microraptor in an arboreal
environment'. If the hypothesis were supported it could strengthen a
scenario where adaptations for roosting in basal paravians exapted the
lineage for later arboreality and gliding. Surely we all do wonder what
factors drove the first evolutionary steps toward flight, and this was a
possibility that occurred to me when I was researching the brooding
behavior of Troodon, oviraptorids, and basal birds. I was surprised to
learn that tinamous brood eggs on the ground, but climb up into low
branches with their chicks just two days or so after hatching. My
hypothesis is really just that this could be a plesiomorphy that extends
all the way back to basal paravians. That would be an AWFUL highly
conserved trait, but that is also not my idea. Varricchio and the other
authors that studied dinosaur nests noted that what is known of Troodon
and oviraptorid nesting is remarkably consistent with living palaeoganths.
>At which point Don's earlier point comes into play: we may not have any
>good way of telling if microraptorans sometimes spent time in trees
>(roosting, etc) unless it could somehow be ruled out entirely (which it
>can't, in this case). I pose the same question I have previously,
>however: what is the justification for trying to put Microraptor in an
>arboreal environment to begin with?
>(Note: I'm not suggesting that Microraptor must have been terrestrial; my
>point is merely that before we start debating arboreal potential, we
>should be clear about why the debate exists in the first place).
>Assistant Professor of Cell and Neurobiology
>Keck School of Medicine of USC
>University of Southern California
>Bishop Research Building; Room 403
>1333 San Pablo Street, Los Angeles 90089-9112