Premise: Mammals are any vertebrates within the class Mammalia ( [ məˈmeɪli.ə ] from Latin mamma #Latin `` breast '' ) , a clade of endothermic amniotes distinguished from reptiles ( including birds ) by the possession of a neocortex ( a region of the brain ) , hair , three middle ear bones and mammary glands . Mammals include the biggest animals on the planet , the great whales . There are around 5450 species of mammal , depending on which authority is cited . Mammals can communicate and vocalize in several different ways , including the production of ultrasound , scent-marking , alarm signals , singing , and echolocation . Most mammals are polygynous , but some can be monogamous or polyandrous .
Hypothesis: Mammals are creatures.
Label: ENTAILMENT