TOPIC 14 (UNIT 3)

Question 1

characteristics of mammalia

Answer 1

1. relatively low species richness
2. largest body size among extant vertebrates (both aquatic and terrestrial)
3. lactation
4. hair
5. 3 middles ear bones
6. red blood cells without nucleus

Question 2

3 subclasses of mammals

Answer 2

1. allotheria
2. prototheria
3. theria

Question 2

allotheria

Answer 2

extinct multituberculates

Question 3

prototheria

Answer 3

monotremes

Question 4

allotheria characteristics

Answer 4

• lived during late jurassic to early cenozoic
• broad multi cusped molars
• viviparous
• herbivorous/omnivourous
• terrestrial or arboreal

Question 5

theria

Answer 5

includes metatheria (marsupials) and eutheria (placentals)

Question 6

extant subclasses and their differences

Answer 6

mammalia -> theria/prototheria

theria -> metatheria/eutheria

prototheria:
- monotremes

metatheria:
- marsupials
- short gestation, long lactation

eutheria:
- placentals
- long gestation, shorter lactation

Question 7

prototheria chracteristics

Answer 7

• cloaca: single opening for excretiry/reproductive
• lay eggs
• no nipples
• no teeth
• electro-sensors on bill
• many have sprawling stance (reptiles)
• ex. platypus, echidna (spiny anteaters)

Question 8

2 different metatheria superorders

Answer 8

1. ameridelphia
2. australidelphia

Question 9

ameridelphia

Answer 9

new world marsupials

superorder, paraphylyl group (has common ancestor but not all descendents)

all marsupials living in the americas

Question 10

australidelphia

Answer 10

marsupials mainly from australia

superorder of marsupials

Question 11

sex determination of mammals

Answer 11

• distinct sex chromosomes: X and Y
• males: XY
• females: XX
• except platypus, which has 5 sex chromosomes

Question 12

eutheria

Answer 12

placentals - in the name

animals that have long gestation periods where the fetus is nourished inside the uterus via placenta

no epipubic bones