Reptiles as Paleoenvironmental Proxies and Their Association with the Climate

Reptiles are animals that depend on external environmental conditions to regulate their body temperature. The temperature is a key factor for the embryonic development in viviparous reptiles and is an important element in biological and ecological processes, such as metabolism, growth, social interactions, reproduction, abundance, and distribution. In this respect, reptiles have relatively limited ranges and preferences of temperatures that they can tolerate, and these ranges differ in species or families of reptiles; then, reptiles should be useful for the determination of past climates. The relationship between climate and reptiles had been used in these organisms as paleothermometers; for example, the tropical affinity in the distribution of crocodilians allow us to infer the climate when we found fossil crocodilians in high latitudes with respect to current distribution range. The presence of giant snakes and lizards during the Paleogene has allowed us to infer the climate with the relationship between the size and temperature in reptiles. In Mexico, the quantitative paleoenvironmental reconstructions with reptiles is very recent; the works carried out include the use of fossil communities, biogeographic, and climatic niche data to infer the paleotemperatures and paleoprecipitation in different Pleistocene sites in Mexico.