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Re: crocs eating hadrosaurs (was Gr. 9 sci proj)



On Jan 7,  8:30am, John Bois wrote:

> "Limiting" here must be used in a strictly technical sense.  Being big
> for dinos may have been a response to ultimately dooming selective
> pressures.  Since mammals don't have the same fecundity problems as
> dinos (after all, they only have to have one offspring to maintain
> populations), they don't have to resort to such ultimately unfit
> strategies as gigantism (relatively speaking).

Unless I've misunderstood what John is saying, this seems to be looking
at mammalian fecundity the wrong way round - surely mammals don't
have small numbers of young because that is sufficient to maintain
the population; this sounds like group selection theory which is impossible
to justify.   Mammals have small numbers of young because of the obligate
parental investment required, both before and after birth.

Mammals that have only one or two young at a time do so because they
cannot raise more than this at any one time.


Tony Canning
tonyc@foe.co.uk