L1 Mills - Mammals

Question 1

What 5 characteristics define a mammal?

Answer 1

1. Mammary glands
2. Live young
3. Hole in the head
4. Sweat glands
5. Fur/hair at some point in their development

Question 2

What is an amniote?

Answer 2

An animal that can lay its egg outside of water

Question 3

Define and give an example for:

a) Anapsid
b) Synapsid
c) Diaspid

Answer 3

a) Anapsid - no hole - turtles
b) Synapsid - 1 fenestra - mammal like reptiles
c) Diaspid - lizards and snakes

Question 4

Why would holes in the skull be an advantage

Answer 4

Muscle attachment

Question 5

What are pelycosaurs?

Answer 5

of all synapsids except for the therapsids and their descendants

Question 6

What are the characteristics of pelycosaurs?

Answer 6

• Spined back - thermoregulation
• Herbivores and carnivores with primate Heterodonty (different sets of teeth for different functions)
• relatively long limbs and a parasagittal gait (dog not lizard walking style) - faster and no pressure on lungs
• elongated neural spines on vertebrae

Question 7

What is the advantage of Therapsids having fewer ribs?

Answer 7

Therapsids are missing lumbar ribs

The introduction of the diaphragm allows much easier breathing

Question 8

What effect does the addition of a secondary palate have on therapsids?

Answer 8

Adding a secondary palate creates a nasal passage with turbine bones. This means:
CAN EAT AND BREATH AT THE SAME TIME

Turbone bones mix and humidify air before it enters the body

Question 9

What are the skull and teeth of Cynodonts like?

Answer 9

Greater Heterodonty

Zygomatic arch

Question 10

What makes a trait homologous?

Answer 10

Common ancestry - without the necessity for similarity of function