Mesozoic life: origin of mammals

Question 1

What are the characteristics of modern mammals

Answer 1

• warm-blooded
• hair/fur
• mammary glands
• live birth

Question 2

what are the 3 different types of skulls possible

Answer 2

1. Anapsid skull
2. Synapsid skull
3. Diapsid skull

Question 3

what are the characteristics of Therapsids

Answer 3

“mammal like reptile”
- fused bones in skull
- larger lower jawbone
- vertically placed legs
- endothermic

Question 4

What are the characteristics of Cynodonts

Answer 4

• had even more mammalian characteristics

Question 5

what were the 3 main groups of mammals

Answer 5

1. Monotremes
2. Marsupials
3. Placentals

Question 6

define monotremes

Answer 6

Egg laying

Question 7

Define marsupials

Answer 7

Pouched

Question 8

Define Placentals

Answer 8

Prolonged Gestation

Question 9

what percentage of mammals are placental

Answer 9

90%

Question 10

what was the impact of the breakup of Pangaea on mammal evolution

Answer 10

marsupials reached Australia from south American and Antarctica
only a few placentals reached Australia

Question 11

What are the differences in teeth in Reptiles and Mammals

Answer 11

Reptiles: lifelong tooth replacement with undifferentiated teeth that are fused to the jaw

Mammals:
- double rooted teeth
- Differentiated teeth
- limited tooth replacement

Question 12

what is the difference of the Occipital Condyle in fish, reptiles, and mammals

Answer 12

Fish: cannot move heads by themselves

reptiles and birds: have single pivot point

mammals: split their occipital condyle into two