| A | B |
|---|
| Monotreme | A mammal that lays eggs |
| Mammal | An endothermice vertebtate with a four chambered heart and skin covered with fur or hair. It feeds its young with milk from the mother's body. |
| Marsupial | A mammal whose young are born at an early stage of development, and which usuaaly continues to develop in a pouch on their mother's body. |
| Mammary Gland | An organ in female mammals that produces milk for the mammal's young. |
| Lift | The difference in pressure between the upper and lower surfaces of a bird's wing that produces an upward force that causes the bird to rise. |
| Gestation Period | The lenght of time between fertilization and birth of a mammal. |
| Gizzard | A muscular, thick-walled part of a bird's stomach that squeezes and grinds food. |
| Diaphragm | A large muscle located at the bottom of a mammal's rib cage that functions in breathing. |
| Down Feather | A short fluffy feather that traps heat and keeps a bird warm. |
| Crop | An internal organ of many birds that stores food. |
| Contour feather | A large feather that helps give shape to a bird's body. |
| Bird | An endothermic vertebrate that lays eggs and has feathers and a four chambered heart. |
| Placenta | An organ in pregnant placental mammals that passes materials between the mother and the embryo. |
| Placental Mammal | A mammal that develops inside its mother's body until its body systems can function independently. |
