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Re: New Refs (short)

I wrote:
> Dinosaurs (as far as we know) never had to adjust to a semi-aquatic living.
Timothy Williams answered:
> One lineage managed it quite well....  :-)  (quack quack)

Yes, I read Donald Duck too :-). But ok, replace dinosaurs with non-avian
dinosaurs. Don't know how often I will fall for this trap.

I wrote:
> In any case crocs are highly adapted to their semi-aquatic niche
> including being ectothermic, semi sprawling and having a special blood
> circulation system. IMHO they are as highly adapted to living in water as 
> birds are adapted to flying.
Timothy Williams answered:
> There are terrestrial crocs too, now extinct.

Yep, but we don't know for certain about the metabolism of these terrestrial 
extinct ones. What I mean is that extant semi-aquatic crocodiles are not a good
model for the metabolism of extinct terrestrial non-avian dinosaurs.

> 2. The maximum size of mammals may be limited by the duration of gestation. 
> The bigger a mammal the longer the gestation period and the lower thenumber 
> of offspring at birth. Surpassing a certain size would have been kind of 
> suicide for a species,
Timothy Williams answered:
> Whales?

To be more precise I meant terrestrial mammals.

I think it's always dangerous to use aquatic or semi-aquatic animals for 
comparison with terrestrial ones.


Heinz Peter Bredow