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Across 5. Each species milk has a different combination of these__________. 8. Mammals also have adaptations for controlling body __________ 10. The first mammals lived on _________, but over time some species adapted to live in watery environments. 12. Scientists think mammals appeared on Earth about 200 _________ years ago. 13. Over millions of years, those early mammals adapted to live in many different _________ and became the diverse group of species they are today 15. Fertilization occurs __________ in mammals. 19. Before a mammal can produce _____________, it finds a mate. 20. The blubber is located between the animals skin and muscles, and provides its organs with _________ from heat and cold. 21. Mammals in a group called the ___________ which includes kangaroo, develop inside the mother at first but are born when they are still extremely small. 24. When a mammal consumes more food than it needs, the extra energy may be stored in its ________ cells. 27. Mammals ___________ sexually. 28. The __________ waste materials leave through the placenta and are transported out of the mothers body along with her waste 29. Body fat can also be s storage place for ________________. 30. Some of then, such as otters and _________, live mostly on water but can also be found on land 31. However, _________ may be the mammal species that takes care of their offspring for the longest time of all.

Down 1. Although there are less than 5000 species of mammals on _______, mammal species come in many shapes and sizes 2. Mice are mammals, and so are cows, elephants, and _____________. 3. Fossil evidence suggests that the first mammals were small land _________ with four limbs, a tail, and specialized teeth. 4. The time when a mammal is developing inside its mother is called ________. 6. Gestation ends when the young animals body has grown and developed enough for it to __________ outside the mother 7. Many mammals have a special organ called a _________ that transports nutrients, water and oxygen from the mothers blood 9. Mammals are __________. This means that they use some of the food they consume to generate body heat. 11. The group of vertebrates called _________ includes many familiar animals. 14. Some species of mammals also have __________ hair. 16. All mammals have ________ during some part of tlheir lives. 17. These mammals have a layer of fat, called___________, 18. All mammal species produce _______, with which they feed their young 22. The duckbilled ________ and two species of spiny anterters have young that hatch from eggs. 23. Some mammal species, such as ___________ and skunks. have adapted to live in many sorts of environments, 25. Mammals bodies have special glands for producing milk called __________ glands. 26. Only one marsupial, the __________ lives in North America.