The pancake tortoise is a fast and agile climber, and is rarely found far from its rocky home so that, if disturbed, it can make a dash for the nearest rock crevice.[6] Since this tortoise could easily be torn apart by predators, it must rely on its speed and flexibility to escape from dangerous situations, rather than withdrawing into its shell.[10] The flexibility of its shell allows the pancake tortoise to crawl into narrow rock crevices to avoid potential predators,[6] thus exploiting an environment that no other tortoise is capable of using.[11]
Don’t see anything about heat.
I admit, I was speculating on the headline. However!
The pictured specimen is a captive one. Not really one subject to avoiding predators or being disturbed.
The ectotherms do a lot of strange things for thermoregulation.
They also can expand their bodies to lock themselves in place, in case a predator with a long beak wants to try and yank them out