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Re: Penguin post script
> Once upon a thread there was a discussion of why penguins are almost
> exlusively southern hemisphere species. I came across a new book called
> Aquagenesis (The Origin and Evolution of Life in the Sea) by Richard
> Ellis. He reviews the penguin fossil record and notes that putative
> penguin ancestors of the Oligocene did exist in the northern
> hemisphere. [...]
> _Tonsala hildegardae_ and _Copept[e?]ryx titan_
How much of a fool do I make of myself when I ask whether these are in
reality plotopterid pelicans? Full-blown penguins are known from the Eocene
of Seymour Island.
> He also quotes Olson and Hasegawa (1996--ref. if needed) as
> saying that "there is a strong possibility that the disappearance of
> (large penguins) is linked with the ascendancy of seals and porpoises."
Does he mean the man-sized penguins of the Eocene like *Anthropornis*? (In
which case I could accept that, but I could probably also invoke the
Eocene-Oligocene mass extinction.)
> 2) Southern continents have fewer and/or less effective predators. This
> enables the existence of these highly vulnerable species (they are the
> only obligatory terrestrial egg-laying species that depends entirely on
> the sea for its food--true?). Antarctica and NZ have no land-based
> predators (I'm excluding avian predators because they are roughly
> constant for N. and S.hemispheres).
Maybe you shouldn't exclude the moa- and (according to Maori tales)
man-eating *Harpagornis moorei*. Anyway, penguins breed on the coasts of
southern and western South America, South Africa and southern Australia
where heaps of predators exist.
> Is it
> possible that seals and penguins are in direct competition for breeding
> sites, but that penguins parents, eggs and chicks can tolerate harsher
> conditions than seal neonates?
The second part of your sentence means that seals and penguins are _not_ in
competition. :-)
> To encapsulate my favored hypothesis: In terms of evolutionary time,
> penguin habitat is ephemeral in the Nth. This is reflected both in the
> lack of diversity in penguin analogues (e.g., the Great Auk),
Plotopteridae en masse.
> And the global
> distribution of seals is a problem for the equatorial barrier
> hypothesis. It assumes that the swimming, foraging, and navigational
> abilities of aquatic dinosaurs are inferior to that of sea-going
> mammals: seals are able to cross the equatorial barrier, penguins are
> not.
Seals and penguins often have different food requirements. For example, many
or all penguins eat lots of krill, AFAIK no seals do.
> This hypothesis assumes that mammals are superior to
> dinosaurs.
What? _In general_???
*******************************************
The climate is getting stranger and stranger. In late December and early
January, when the "Christmas defrost weather" has become normal,
temperatures regularly reached down to -10 °C, then we got late spring with
temperatures regularly reaching up to +20 °C, then (after unusually strong
winds) came early spring, and today we've surprisingly received a centimeter
of snow. TV sez the Gulf Stream has already weakened by 20 %.