Re: Raptor Claws(formerly Triceratops Frills)

["Nicholas R. Longrich" <longrich@phoenix.Princeton.EDU>]

On Tue, 23 Jan 1996, GROSS CORY WALTER wrote:

> Date sent:      Tue, 23 Jan 1996 13:06:16 -0500
> From:           martin@hpentccl.grenoble.hp.com (veni, vidi, concreti)
> Subject:        Triceratops Frills
> To:             Multiple recipients of list <dinosaur@lepomis.psych.upenn.edu>
> Send reply to:  martin@hpentccl.grenoble.hp.com
         
>         I think that it's wholly reasonable to assume that some 
> animals, especially Dromaeosaurids, limited themselves to attacking 
> certain types of animals (with the occasional rodent hordeurve? mixed 
> in). I'm toying with this idea right now that I suppose I may publish 
> sometime; and the basic gist of it is that Dromaeosaurs were so well 
> adapted to hunting certain prey that if something happened to the 
> food, then our fair dino's were dead in the water (it's a bit of an 
> expansion on punc. eq.). If you look at the record, it seems that 
> Droms. suffered a horrid rate of extinction for an animal that was 
> such an apparently good hunter; so it seems that if...say a new 
> hunter took their prey animals away, or they hunted their own prey 
> into extinction(my...how P.C. ;-)), they couldn't really hunt 
> anything else. It's a little oversimplified, but it ain't the whole 
> hypo. either.

        Wolves spend a great deal of their time hunting rodents (voles, I 
assume) up in Canada when nothing else is available. I've heard, and I 
can't remember where, that feral cats in the Galapagos have taken up 
eating insects, of all things. Galapagos finches with big bills designed 
to crack open big seeds will take small seeds when they are available and 
nothing else is. 
        Animals aren't locked into behaviors by their morphology. Small 
game hunters can probably take bigger game when they have to, big game 
hunters can certainly take small game when they have to. They're just not 
as good at it, that's all. Imagine switching the places of a jockey and a 
linebacker. One could do what the other does, just not nearly as well 
because of morphological differences. 
        The big-bill Darwin's finch, for a less hypothetical example, 
can take the small seeds, but it expends more energy and gets less energy 
back than the small-billed finches, and being bigger, the big-bills take 
more of these seeds. So they can do it, but the small-bills will 
outcompete them. The situation is reversed when big seeds are plentiful.
        I'd think that it's likely that a lot 
of the time the behavioral changes predate the morphological changes. In 
a hypothetical case, cats with dentition suited to eating insects would 
eventually outcompete the other cats in the Galapagos, smaller cats would 
probably survive better as well, and eventually in however many 
generations you'd have insectivorous cats, perhaps. 

        -nick L.