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Re: Triassic Guaibasaurus slept like a bird


> While it is true the desert nights would be cold, and a proto-Humboldt would 
> indeed cool the western margin of Pangaea, that
> proto-Humboldt would be nowhere as cold as present.

Fair enough! What takes me aback in these discussions is that people
conflate climate with weather, so much so, I even did that on my
previous e-mail.

"(...) I'm not sure I would expect much difference
(perhaps more extreme climate[read: weather]) from my situation living in a
Mediterranean region (...)"

Average global or regional temperatures, because of their statistical
nature, can say only so much about the actual seasonal or daily
variation. The latter would be far more informative in teasing out the
thermoregulatory strategies employed by dinosaurs, and other
That brings me to one of my annoyances in scientific discourse:
speaking only in relative terms and not quantifying... I mean, without
numbers to ground adjectives such as "colder" or "warmer" in fact (or
at the very least, explicit models) these words tend to
meaninglessness in my view.
I remember from discussion elsewhere that lepidosaurs overall need to
avoid frost, http://www.bcreptiles.ca/reptiles_north.htm#survive , and
I think that could be a good benchmark for other fully scaled
tetrapods. There's also the need for climate simulations that at least
distinguish average season temperatures,
http://www.geo.lsa.umich.edu/paleoclimate/pdfs/huynh_poulsen2005.pdf ,
even if they should be taken with the appropriate dosage of salt. Note
that figure 4 shows the June/July/August average surface air
temperatures for the 2x and 4x pre-industrial CO2 levels that area of
the world would be from -4 to 12 ºC, which would at least mean heavy
frost for the southern part of that range. This is also bolstered by
figure 3 which shows both the average annual temperature and the
annual temperature range for those scenarios.

> The extreme cold of Antarctic waters (and Antarctica, and the Antarctic 
> Bottom Water, which spills along the bottom of the sea well
> into the northern hemisphere) is due largely to the presence of a 
> circum-Antarctic current. There is thus an uniterrupted flow of
> water at very high latitudes not deflected up into more equatorial waters, 
> allowing for the development of the coldest, densest
> waters too form.

True: the simulation mentioned above bears this out as proximity to
the ocean drastically diminishes the annual temperature range. The
cold current effect only seems to be discernible during the austral

> Prior to the separation of Antarctica from its Gondwanan sister-continents, a 
> circum-Antarctic current was impossible and thus the
> polar waters and polar regions were considerably warmer than at present.

Yet there was a Permo-Carboniferous glaciation.
Though that was probably due to a combination of the continental mass
at the South Pole being cold enough to accumulate ice and there being
a source of humidity and thus snowfall in the Paleo-tethys north of
Eastern Gondwana, which does not necessarily mean as cold temperatures
as there are today in Antarctica.

Renato Santos