I don't own much herp literature so maybe someone can help with some info: What chameleon species regularly endure the worst temperature extremes of both cold and heat?

I would have to say chamaeleo namaquensis.
http://www.adcham.com/html/taxonomy/...maquensis.html

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C. namaquensis takes the heat. But which alpine species tolerates the lowest low? Petr Necas says Trioceros schubotzi occurs at 4500 m. (14,760 ft.) on Mt Kenya. Sounds like it must endure regular exposure to freezing. T. hoehnelii does too.

Others?

T. hoehnelii lives at a slightly lower elevation then T. schubotzi. T. schubotzi habitat is known to commonly drop to just below freezing. They probably have the lowest temperature extreme. Interestingly chameleons are still able to feed at very low temperature. Bradypodion pumilum has been observed feeding with a body temperature of 3.5 degrees C while T. hoehnelii has been observed feeding with a body temp of 7C. As has already been mentioned, Ch. namaquensis probably has the highest temperature extreme with temps in the Namib desert easily reaching over 40C during the day.

Chris

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Those namaquas might go through the widest temp swing day to night too. Deserts can get quite cold at night- anyone know for sure?

Burrage (1973) states "The body temperatures of active Chamaeleo namaquensis are remarkably stable, despite the varied environmental temperatures of the Namib Desert. On foggy mornings the substrate temperature was as low as 8,0 C; but on clear, sunny days the substrate temperature reached 67,0 C. Of 351 active C. namaquensis body temperatures recorded in the field, the overall range was 14,0-39.7 C; mean 28,7 C; median 28,8 C." He goes on to state that "Field records (N=18) of C. namaquensis at rest ranged from (Coastal N=11) 7,0-13,0 C (mean=10,6 C), and (Inland N=7) 9,0-16,0 C (mean=12,3 C) and were about that of the substrate."

Chris

hmm. Would it be possible to own one?

In short, no. They are protected from export and previous attempts to keep them in captivity showed them to be extremely difficult to keep and resulted in the death of all individuals, CH and WC, in a fairly short period.

Chris

I've been thinking about the record of Trioceros (Chameleo) schubotzi at 4500 m. It kind of blows my mind.

The type locality is listed as 4000 meters a.s.l. ( 13,120 ft. ) This is quite remarkable, and must make this chameleon one of the highest altitude reptiles in the world. Beside the required adaptation to temperature extremes, there would be a scarcity of insects, low oxygen levels, low humidity, and very high UV radiation, all making it a very challenging environment.

Habitat at that height on the mountain is alpine grassland and cracked ground from the constant freezing and thawing. Just a little higher at 4600 m. was the lowest reaches of the Tyndall Glacier; now it has retreated considerably higher. A bit lower is the heathland habitat that supports giant Lobelias and tree Senicios. This would seem to be a more plausible environment for a reptile, but still a harsh one.

T. schubotzi sounds like a marvel. Does anyone have experience of this animal?

BTW, The type locality for T. hoehnelii altaelgonis is 3,500 m. on Mt Elgon, Uganda/Kenya. A very similar habitat to the above sp., but with more vegetation. Mt Egon's highest peak is 4321 m.

Well, I looked for some pics of Trioceros (Chameleo) schubotzi but I did not have much luck.

Anyway, these kinds of animals are very interesting. For example, I heard there is a salamander that lives exclusively under chunks of slate on half dome in yosemite. Lots of other animals' ranges are apparently due to mountaintops serving as habitat islands from warmer times -- they did not hike up there over generations but just got stuck and as temps dropped they adapted.

I feel like chameleons from colder climates have unique scales, anyone else see that?