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Re: Microraptor also ate fish



In response to Jason, two points:

(1) There is a difference between what an animal is adapted for, and
what it is capable of.  Obviously, the latter is more expansive than
the former.  (I can climb some trees - but I have no arboreal
adaptations.)  However, if an animal is not morphologically adapted
for a certain behavior, then I think it is dangerous to argue that
this behavior was central to its ecology.

You say, quite reasonably: "Thus I defend any researcher who presents
a hypothesis about extinct animals based on observations of living
animals."  However... unless that hypothesis is testable (e.g., by
biomechanics, morphometrics, etc), then it is just speculation.  (BTW,
speculation is fine - as long as it's presented as such.)


(2) I think we agree broadly that _Microraptor_ spent much of its time
on the ground.  As you say: "If you'll recall, my hypothesis was that
it may have foraged on the ground and roosted in trees, as do the
clades of living basal birds that are small enough to do so."

This is a prime example of why I'm so uneasy about using living birds
as analogs for non-avian maniraptorans.  Unless you can reconstruct
exactly *how* _Microraptor_ roosted in trees, the comparison between
_Microraptor_ and a roosting bird is entirely meaningless IMHO.  Yes,
some extant birds can roost without the benefit of a perching pes
(like certain tinamous).  But unless _Microraptor_ roosted in the same
manner as one of these birds, what's the relevance?  This sounds like
a hypothesis waiting to be tested.  Unless there is a methodology in
mind, then it's just speculation.

I would sum up your argument as "If small birds can roost, why not
_Microraptor_?"  But what I want to know is "Why?" and "How?" - not
just "Why not?"

Too often, analogs based on superficial or trivial similarities are
used to cut corners.  Someone finds a point of anatomical similarity
between (say) _Microraptor_ and a flying lemur.  They then claim that
_Microraptor_ behaved in the same way as a flying lemur.  There is a
fine line between being "unrealistically constrained" and outright
bullsh*t.

The paper by Birn-Jeffery et al. (2012) corroborates the hypothesis
that _Microraptor_ and friends might have been scansorial.  What you
call arboreal features are actually scansorial (i.e., used for
climbing).  But climbing up (or on) what?  Many small mammals are
scansorial, but spend hardly any time in trees.  Because these
furballs are small in size, walking or running over uneven terrain
requires scansorial adaptations.  (I've wondered if this was the
adaptive rationale behind the scansorial features in tiny
_Epidendrosaurus_/_Scansoriopteryx_ i.e., nothing to do with
arboreality.)






Cheers

Tim