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Re: Spinosaurs show semi-aquatic oxygen isotopes



--- On Fri, 2/5/10, Augusto Haro <augustoharo@gmail.com> wrote:

> Do you need a very specialized postcranium to live most of
> your time
> in the water like a hyppopotamus or crocodile?

Given their relatively long front legs (compared to tyrannosaurids), and 
general size and power, I would say "no", unless one assumes they were 
constantly swimming. As you say below, they might find that unnecessary. They 
were too big to live like otters...

Spinosaurids would have logically needed to traverse terrain separating 
waterbodies/wetlands, in response to drought, flood or food/mate shortage. 
Also, the presumed need to nest and lay eggs would maintain terrestrial 
competence. 

As spino's were very large, any of the "expected" locomotive adaptations to 
semi-aquatic life usually cited in these discussions would have involved a very 
large trade-off in dry-land competence, and were probably undesirable 
design-wise in a wading lifestyle, anyway.

> I do not see a cursorial-looking animal going so bad in the
> water.

I agree, at least as a wader. 

> If its neck moved
> fast enough to
> catch something, it seems it may not have great trouble...

It could have stirred up a lot of silt in shallow (<2-3m) water. Modern gilled 
fish have a tendency to pass out and float belly-up when that happens, making 
them a free lunch.

Just my opinion...