| A | B |
|---|
| amniote | vertebrate having an amnion surrounding the embryo; reptile, bird, or mammal |
| amniote egg | waterproof egg with a shell |
| scale | hard structure made of keratin that is part of the skin of reptiles, fishes, and some other animals |
| ectotherm | animal whose main source of body heat is the external environment |
| endotherm | animal whose main source of body heat is generated from cell metabolism |
| feather | type of modified scale made of keratin; characteristic of birds |
| gizzard | muscular organ, often containing small stones, that grinds seeds and other foods |
| crop | saclike food storage organ found in most birds |
| mammal | member of a group of endothermic vertebrates with mammary glands and hair |
| monotreme | member of a group of mammals that lays eggs |
| marsupial | member of a group of pouched mammals whose embryos are born before development is complete |
| placental mammal | member of a group of mammals whose embryos complete their development within the mother's uterus |
| primate | member of a group of mammals that includes lemurs, monkeys, apes, and humans |
| prehensile tail | grasping tail that functions as an extra appendage, such as for swinging through trees |
| hominid | member of the family of species that includes Homo sapiens |
| bipedalism | ability to walk upright on two feet |
