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Re: Microraptor ate birds



Am 11.11.2011 17:40, schrieb Denver Fowler:

 I don't think it would be beyond reason to do a little survey of
 extant predators that eat "arboreal" birds, and see just how
 regularly said birds are caught in trees as opposed to on the ground.
 This wasn't done, merely an assumption was made (not the least, the
 assumption of arboreality on the prey's behalf). I understand this is
 a poster, not a peer-reviewed paper;

SVP meeting abstracts do get reviewed, though. And 30 % or more of them are rejected. (No more T. R. Karbek on bipedal cursorial stegosaurs, alas.) Of course, the reviewers have only the submitted abstract to go with, not the unpublished evidence that supports it, but this abstract should have raised questions...

Or maybe the reviewers figured any excuse for showing us that specimen was fine. I'd understand that. :-)

 these sorts of conclusions shouldn't make it into print without a
 proper assessment of the data, but frequently we see misinformation
 making it through. The original Microraptor gui description had a
 reconstruction of a splayed-limb glider -at odds with known anatomy
 of dinosaurs; indeed the upright unsplaying hindlimb is one of THE
 dinosaurian features emphasized in the most basic undergraduate
 classes on dinosaurs; I can;t understand how this was missed by both
 researchers and reviewers alike.

What you say is true but not a very good argument. Autapomorphies happen; in this case, a few specialized reed-living passerines can indeed sprawl.

A better argument is that horizontal hindlimbs are at odds with the known anatomy of _*Microraptor*_. Given the description and photos by Hwang et al. (2002), the describers of *M. gui* should have been requested to explain (at the very least in the supplementary information, which isn't under space restrictions!) why they thought *M. gui* was capable of such sprawling -- other than being used to mammalian anatomy (femur with spherical head and long, pinched neck) and having encountered the "Tetrapteryx" hypothesis.

BTW, is there a detailed description of *M. gui* in the works? That 4-page Nature paper is all that's published.

 Yes, it's paleobiological data. Evidence of some trophic interaction.
 This part is very interesting. I like the point made by someone else
 that it is little different from finding fish remains in
 confusciusiornithids: does this mean they were waterbirds that always
 eat fish?

This was proposed at the zoology conference in Paris a few years ago by A. Zinovi"e"v. He thinks this is what a fish-eating bird that lives in a place with trees and cannot lift off from the ground looks like. However, I wonder about the beak shape and the surprisingly robust skull. (The beak isn't very long, and it has completely straight margins that don't seem good for catching anything slippery.)

 what is the difference between catching prey and killing prey?

Falconids usually catch prey, then kill it (very quickly) if the impact didn't already kill it, then eat it. Accipitrids usually catch prey, then (if the impact didn't kill it) only kill it by eating it -- while flapping a lot to stay on top of the prey, a fact I should have remembered (from a previous SVP meeting) for another thread.

Bears kill salmon by ripping them apart and eating them, as seen on TV.

Snakes kill dangerous prey. Harmless prey, and poisonous prey that doesn't get less dangerous by dying, they swallow alive.

Most frogs catch prey by swallowing it. True toads don't even have any teeth, nor the fake teeth found in the lower jaws of some frogs like *Hemiphractus* that eat large, dangerous prey.

 Does the bald eagle only eat fish?

Rhetorical question, right? It's a generalist scavenger in addition to catching fish.