What makes a mammal a mammal? Several things! Like other vertebrates, they have a skeleton on the inside of their bodies (endoskeleton). These bones are wrapped by muscle, tendons, veins and skin. Mammals have lower jaw that is hinged directly to the rest of the skull. Other vertebrates’ lower jaws hook indirectly to the skull. Mammals have hair… some more than others! This hair can be whiskers, spines (like on the porcupine), prickles, horns or fur. Some mammals are born bald and get hair as they age. Others like whales have hair when they are born. Mammals give live birth. Of course, there are always exceptions, like the duck-billed platypus and four species of echidnas, which lay eggs. Marsupials give live birth, but keep their young in pouches until developed. Female mammals produce milk for their young. If you come across an animal that has these features, you have found a mammal.
