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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
> 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
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
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 %.