mammals

Question 1

key characteristsics of mammals

Answer 1

• mammary glands
• cheek muscles and lips
• endotherms (inside heated by oxidizing food)
• body covered with hair/fur

Question 2

when did the earliest mammals in fossil record appear

Answer 2

195 mya

Question 3

when did mammals begin to diversify

Answer 3

when dinos and other reptiles were dominant large herbivores and predators

Question 4

three major lineages of mammals alive today

Answer 4

1. egg-laying monotrems
2. pouch-bearing marsupials
3. eutharians (placenta)

Question 5

placenta

Answer 5

rich in blood vessels that floe O2 and nutrients to embryo and removes nitrogeneous waste and CO2

Question 6

evolutionary advantages of viviparity and placenta

Answer 6

1. offspring develop at a more constant, favorable temperature
2. offspring are protected
3. offspring are portable - mothers arent tied to a nest

Question 7

tade offs of having a placenta

Answer 7

lots of energy
giving birth is dangerous