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Re: attack on dinosaur--horrific video



On 11/25/07, john bois <jbois@verizon.net> wrote:
>
> ----- Original Message -----
> From: "Andreas Johansson" <andreasj@gmail.com>
> To: <dinosaur@usc.edu>
> Sent: Saturday, November 24, 2007 6:10 PM
> Subject: Re: attack on dinosaur--horrific video
>
>
> > Shouldn't we also see a driven trend to larger size in Cenozoic
> > oviparous amniotes?
>
> My point is that today, at least, this strategy is not viable...otherwise we
> would, indeed, see it.  But crocs are the _only_ oviparous species that
> "choose" defense over concealment and remote laying.  Concealment carries
> selection on _small_ size; whereas remote laying selects for long distance
> flying.
>
> > I'm not seeing why egg-predation by placentalians would affect
> > mesozoic dinosaurs differently from other egg-laying amniotes.
>
> Not just placentals...but, anyway...birds can conceal and fly to
> out-of-the-way places; crocs are just special; snakes and lizards conceal
> (usually); turtles generally lay in out-of-the-way places and swamp
> predators.

Allowing that most Mesozoic dinosaurs couldn't fly, the same options
were open to them. That's why I'm not seeing why there should be a
difference.

But if you're not just talking about placentalians, I really don't see
how you can postulate any special significance for egg predation at
the KT boundary. Eutherian (and thus presumably viviparous) mammals
are known from at least 125 Ma, possible crown mammals form the
Jurassic. Any dinosaur alive in the end Cretaceous had necessarily
evolved to cope with egg-hungry mammals over a very long time,
excepting only possible very isolated groups analogous to the
albatrosses of the video.

--
Andreas Johansson

Why can't you be a non-conformist just like everybody else?