Are reptiles warm blooded?
No: by definition, they are cold blooded. Their body temperature fluctuates with the conditions of their environment, and they require external heating (e.g. sunlight or for those in captivity, heat lamps) to warm them up sufficiently to undertake "normal" activities.
Cold bloodedness used to describe them is misleading, however, leaving one to believe that their blood is always cold. The term herpetologists (a person who studies reptiles & amphibians) use is poikilothermal. This means, as described above, that their body temperatures changes with their surroundings. Their body will feel cold if the ambient temperature is cold and warm if the ambient tempertature is warm.
- Actually the above is answer is incorrect, neither "cold-bloodedness" nor "warm-bloodedness" define any group of animals, as that only loosely refers to their metabolisms, which vary across and within various animal groups.
Poikilothermy refers to variation in body temperature.
Homeothermy refers to maintenance of a steady body temperature.
For example: Birds are reptiles by definition and diagnosis and are endothermic or "warm-blooded", but some are homeothermic and some are poikilothermic.
The same can be said about many mammals.
The truth is that some reptiles are, or were endotherms (create their body heat metabolically) and that some are, or were ectothermic (raise their temperature from ambient external sources).
Other reptiles such as extinct dinosaurs and pterosaurs, were also endothermic based on tremendous amounts of data.
The metabolism of animals should not be considered in black and white terms, there is a continuum along which many metabolic strategies are used by different critters.
- There needs to be more clarification than presented in the previous post. Truly warm blooded is a polyphyletic trait that can be found across multiple different families of organisms and it generally has occurred due to a Lamarckist evolutionary characteristic in which was founded that organisms that begin to act upon habit upon traveling into different environments would begin to develop a system of internal metabolism of what we call Warmblooded, but of course there are three distinguish characteristics of warm blood and different variations of those three characteristics.
It is important to note that Crocodiles do in fact come from a cold-blooded organism, but relative isolation to sole and single environment had reverted them back to cold-blooded organisms. This is also true when it comes to Bats who aren't truly warm-blooded organisms and spend a great amount of their time in a single-sole environment, thus less need for adaption and as a result more fixation on environmental survival instead. The bird, which was its relative probably wasn't so fortunate to be in such a marshy environment as the Dinosaur Age began to end and thus remained warm blooded, because it still had to adapt to a changing environment.
It just points out how important the environment to an organism is on how it will evolve.
Nevertheless, being warm blooded is ultimately a significant factor in order to develop into a highly advance and intelligent species. Other two important characteristics are an ambush predatory behavior and a physical design that allows the act of grabbing and using material from the ground, something we take for granted, called hands.
Human evolution had occurred on the first remark of being a warm-blooded descendent of synapsids, which a division of amniotes that bounds us to birds and reptiles. The term reptile is generally incorrect nowadays, we instead use saurapsid to include not only reptiles but also birds. Due to the fact that certain reptiles such as Crocodiles are closer related to birds than they are to other reptiles.
The next important step to our evolution was developing hands to grab things, which we ultimately acquired by being a descendent of an arboreal organism called a Lemur, which makes us Primates.
Following that we had to develop an ambush predatory behavior, which can be seen in chimps and is a reason why we are both members of the Hominina Tribe and why Chimps are our closest primate relative, beside the fact we both don't have tails (which is why otherwise we could been more closer related baboons).
I hope that resolves a lot of difficulty on understanding cold-blooded and warm-blooded organisms as well as evolution and as it pertains to humans and intelligence.