What makes a REPTILE a REPTILE? Reptiles are ECTOTHERMS, which means they don’t keep their bodies warm by themselves—they need to depend on other sources, like the sun, or warm places!
But, not all endotherms are reptiles! In the end, being a reptile all comes down to the BONES! Scientists look at the skulls of creatures to identify reptiles throughout the fossil record. As they evolved, reptiles started to have more holes in their skulls where muscles could grow and better support their heads. These DIAPSID skulls were different than SYNAPSID skulls that are used to identify mammals!
What type of reptile is your favorite?