What is the difference between a dinosaur and a mammal?
First and foremost, mammary glands. These are the defining feature of mammals, and give them their name. They are the glands that produce milk to feed to the young. Only mammals have them, and no other animals do. If something has mammary glands, it’s a mammal, and if it doesn’t, it isn’t. Dinosaurs were reptiles. They did not have mammary glands. They had scaly skin or, in some species, feathers, whilst all mammals have at least some hair. The dinosaurs laid eggs, whilst most mammals (though not all) give birth to live young. Most dinosaurs were cold-blooded, whilst all mammals are warm-blooded (some dinosaurs are thought to have been warm-blooded, but certainly not all of them. Something the size of the sauropods would soon overheat if it were warm-blooded). Dinosaurs had teeth of all one type, whilst mammals have differentiated teeth – incisors, molars, canines, etc. The lower jaw of dinosaurs was made up of more than one bone, whilst the lower jaw of most mammals is a single bone.
