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Re: Microraptor also ate fish



Dann Pigdon <dannj@alphalink.com.au> wrote:

>> But the fact that a
>> predatory theropod sometimes ate birds and fish makes me wonder if it
>> had adaptations consistent with catching birds and fish.
>
> Canopy fishing, like a black heron perhaps?
>
> http://www.flickr.com/photos/tonif/8179939301/
>
> *Microraptor* seems to have had similar colouration. It would have got its 
> leg feathers wet
> though.


This 'canopy fishing' heron-like behavior was once proposed for
_Archaeopteryx_ to explain the origin of feathered wings (Thulborn and
Hamley, 1985).  The paper even posits that feather asymmetry is an
adaptation to canopy fishing, by producing a more "economical" wing
that minimizes overlap of individual feathers (or something like
that).


Thulborn, R. A. and T. L. Hamley. 1985. A new palaeontological role
for _Archaeopteryx_. In: M. K. Hecht, J. H. Ostrom, G. Viohl, and P.
Wellnhofer, (Eds.), The beginnings of birds, pp. 81–89.



Don Ohmes <d_ohmes@yahoo.com> wrote:

> If an animal has the tools to catch live fish, predation is a much reliable 
> method of obtaining a
> given quantity of food than scavenging, special conditions like anoxic events 
> excepted.
>
> It follows that when an animal which clearly has the tools for predation is 
> found with
> prey-appropriate organisms in it's gut, predation is parsimonious - predation 
> being ecologically
> more viable.


Yep, I agree.  Which brings me to Mickey's post....



Mickey Mortimer <mickey_mortimer111@msn.com> wrote:

> I note you didn't even reply to my single Ornithomimus footprint analogy.  
> What makes the
> situations different in your eyes?


The _Ornithomimus_ analogy struck me as a non sequitur.  A single
footprint is just that - something we might expect of any terrestrial
theropod.  By contrast, prey preference may vary between individual
taxa.  These prey preferences are determined by adaptations that may
differentiate these taxa.


> None of what you said makes predation of the fish more parsimonious.  To be 
> so, it would have
> to explain the
> data better than scavenging, and you admit in the last paragraph scavenging 
> fish requires no
> special
> morphology for a theropod.  So hunting fits its morphology well, and 
> scavenging fits its
> morphology well.


Not quite.  Hunting of certain prey "fits" what is specifically
inferred based on morphology.  Opportunistic scavenging does not "fit"
any specific morphology (beyond what one might expect of a predator or
carnivore).  So it difficult to frame a morphology-based hypothesis
that an animal was an opportunistic scavenger.


Let's say we propose a hypothesis regarding prey preference based on a
predator's morphology, such as that the predator was a fish-eater
(piscivore).  We then find a specimen of this predator that has a fish
inside its abdominal cavity.  I'd say we have evidence that is
consistent with this hypothesis.  Not hard proof; I won't go that far.
 One swallow doesn't make a summer, and one ingested fish doesn't make
a piscivorous theropod.  But it's a start.


>From another post...

> Not that the Confuciusornis / wood duck thing has anything to do with Xing et 
> al., since they
> don't make the Sinocalliopteryx point you did, but...  are wood ducks' legs 
> actually notably
> shorter than Confuciusornis', or do they just look that way due to feathers 
> making the body
> seem bigger and only the tarsometatarsi being exposed?  Also, Confuciusornis 
> pedal unguals
> are much larger and more curved than the wood duck's, so I don't see why you 
> think the latter
> are better adapted for perching.


This is one example of why I hesitate to apply the word "bird" to any
avialan that lies outside the crown group.  _Confuciusornis_ was a
long way from being a crown avian, and it was nothing like a duck.
Aside from both being pygostylian avialans, that is.  So just because
a certain species of duck can do something (perch) without the aid of
an enlarged hallux doesn't mean any basal avialan can do it.  Again,
I'm tying certain behaviors to specific adaptations here.  Even among
crown birds, wood ducks are exceptional in being perchers that have
short halluces.  But perching is achieved in other ways, and I'd bet
that the gross morphology (including the very short effective
hindlimb, and forwardly displaced center of mass) has something to do
with maintaining a stable posture when the bird is sitting on a
branch.  Given the wide gulf in overall proportions between
_Confuciusornis_ and a wood duck, extrapolating the behavior of the
latter to the former is drawing a long bow indeed, IMHO.








Cheers

Tim