RE: mosasaur babies/no marine dinos

[John Bois <jbois@umd5.umd.edu>]

On Tue, 1 Jan 2002, Tracy L. Ford wrote:

> I'm not sure I understand what your saying. Are you saying NO dinosaur could
> have lived an aquatic life (in rivers, etc) or are you saying no dinosaur
> could live a MARINE life like a Marine iguana?

I'm proposing that no dinosaur could compete in the whale/mosasaur
habitat, i.e., be big and a completely an open sea-faring
creature--independent of land.





> *   There is more oxygen in air than water.  Penguins demonstrate
> the effectiveness of the body plan as a fishing machine.  But, the oxygen
> requirement means that eggs must be placed on land.  This limits
> size-inasmuch as birds designed for swimming are clumsy on land (imagine an
> elephant seal incubating an egg).  So, ectotherms and placentals are the
> only large size animals to rule the waves
> To summarize: archosaurs are very efficient fish hunters but are
> size-limited in the marine environment.  This is due to a) high oxygen
> demand for developing egg/embryo; b) inability to incubate a land egg with a
> fish body plan.<<
> *
> * Penguins also live in colder waters and need to be warm blooded to do so
> (though some do come into warmer waters). Penguins aren't a good analogy for
> dinosaurs, they are too advanced.
> 
> A related phenomenon is the distribution of penguins.  Given their great
> fishing ability, they should be competitive in all parts of the world.  But
> their distribution is primarily southern.  I believe nest sites are the
> limiting factor here; that is, nest sites and predator abundance--which
> amounts to the same thing--nest sites without predators are much more common
> in the Southern H. than the Northern.
> Comments welcome.<<
> I believe some sort of aquatic lifestyle was possible for some dinosaurs.
> Why are there so many Hadrosaurs and ankylosaurs found in marine deposits?
> Have they all been swept out too sea? Not having dinosaurs living near the
> waters edge, whether it is lagoonal, estuarine, shoreline, etc is taking out
> an ecological niche. The niche was there and it WAS filled.
> 
> Tracy L. Ford
> P. O. Box 1171
> Poway Ca  92074
> *
>