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Re: Hot-blooded marine reptiles
You're right, Dann, but you have to see the data presented in this paper
as additional evidence for endothermy in ichthyosaurs, plesiosaurs, and
Another interesting result is the body temperature variation within
Ichthyosauria, compared to plesiosaurs and mosasaurs. Also, given what
was known from ichthyosaur biology and functional anatomy, it was
expected to find a lower body temperature in *Mixosaurus* than in
Bristish thunnosaurs. These new results confirms this difference, even
if the effect of size is still poorly understood AFAIK.
I expect future comparisons with Triassic taxa such as Shastasauria
(*Shonisaurus* !), Eurhinosauria, or non-Ichthyosauria Ichthyopterygia
(*Utatsusaurus* or Grippidia).
Regarding endothermy, it should not be forgotten that ichthyosaur high
metabolic rates have probably been favoured by a global increase in size
during Triassic, leading to higher thermic inerty ("gigantothermy). And
that is why I am waiting eagerly for more investigations regarding giant
forms (*Shonisaurus* and his relative *Himalayasaurus*).
Dann Pigdon a écrit :
The idea of high body temperatures in extinct marine reptiles isn't a complete surprise. Tuna and
some sharks managed to maintain high internal temperatures by piping blood past their muscles
like a biological central heating system. 'Waste' heat from muscle activity is thus used to heat the
blood rather than actually being wasted.
Bluefin tuna have a particularly efficient thermoregulatory system that keeps their internal
temperature between 24 and 35 degrees celcius (depending on the temperature of the surrounding
water). Who needs endothermy when you've got your own built-in central heating?