Re: mosasaur babies/no marine dinos

["David Marjanovic" <david.marjanovic@gmx.at>]

> > Why are there no penguins in the northern hemisphere and never have
been?
> > Today they only live in cold currents that produce blooming ecosystems,
and
> > they evolved in the south, so I'd say they have never got farther north
than
> > Galápagos and are unable to cross the equator.
>
> Then two competing hypotheses: equatorial barrier and unsuitable nesting
> sites.  What do you propose as a significant barrier that stops penguins
> but not any other body form from extending their range.  I mean, they
> could edge up the coast of South America or Africa.

Said cold south-north currents, which support lots of krill and fish, stop
somewhere and drift off to the west. The Humboldt Stream west of SA drifts
off almost at the equator, and so far up do penguins occur. The Benguela
Stream west of Africa does that sooner, IIRC.

> Granted "blooming
> ecosystems" fuel penguin ecology...but I can't see this as forcing
> complete exclusion...one might expect, for example, changing weather
> patterns (el Nino) to temporarily extend their range...

El Niño does the opposite, it shuts down the Humboldt Stream and brings
death to SA's west coast. La Niña doesn't make the Humboldt Stream cross the
equator either.