Now the leatherback turtle overcame the heat issue via a simple, but evolutionarily impossible solution; it is the only reptile that possesses fatty insulation known as brown adipose tissue, and the only reptile that regulates a high body temperature. This brown adipose tissue is the expression of the UCP1 gene, and, aside from the leatherbacks, is found only in mammals, amphibians, and fishes. Not one other reptile has UCP1.
