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Re: The Final Days



Original Message by Tim Donovan Sunday, 17. November 2002 11:51

> >Being generalist predators certainly helped,
>
>   Apparently not in the case of dyrosaurs which, judging by their slender
> snouts, were probably specialized fish eaters.

It is certainly reasonable to assume that, when there were enough fish, 
dyrosaurs ate almost only fish. But phytosaurs with very similar snouts are 
known with rhynchosaurs and prolacertiforms as stomach contents, so I don't 
think dyrosaurs were totally dependent on fish.
        And even if... at Stevns Klint the boundary layer is called "fish 
clay", 
isn't it? Judging from that, dyrosaurs could have been disaster species.
        Is anything known about whether dyrosaurs already hatched with such 
snouts?

> >Another thing: small juvenile crocs are finger food for a wide range of
> >critters.
>
>   Varanids, birds, felines,turtles, even carnivorous fish. It is  true that
> at the K-T, there were no likely mammalian predators, and some other
> predators might have suffered temporary losses.

_All_ other predators are expected to have suffered heavy losses, temporary 
or not. Of course some generalist/scavenging disaster species are expected to 
have become very common after the impact winter, but evidence for this 
short-time event is AFAIK lacking so far.

> [...] predation [...] was [...] likely intensified in the hypothesized,
> energy depleted environment.

Apparently the numbers of individuals were not high enough for intensified 
predation. Or a lot of such species would have made themselves, and much of 
their prey, extinct. :-) Coming to think of it, maybe this was what killed 
off the last small nonavian theropods. But that's pure speculation, 
untestable at least as long as we don't understand their population 
dynamics...