Mammals primates and the biological basis for behaviour. Motile, derive energy from ingested food (shows we are animals) Have dorsal never chord with surrounding bony vertebrae (shows we are vertebrates) Mammary glands (nurse young with milk from these glands) Legs are under the body for efficient energetics. Heterodont dentition (have incisors, canines, premolars, molars) where as reptiles are homodont because all their teeth are the same little points. Mandible is a single bone (dentary) and in reptiles it is made of many different bones. When we look at fossils we want to be able to distinguish what they are. Specialized at being generalists and can do many different things. Hard to form a pattern of locomotion because many move in different ways, also hard to form a pattern of diet because they eat many things. Generalized heterodont dentition and a lack of specialised diet.