Lecture 15

Question 1

Traditional Mammal Evolution Ideas (3):

Answer 1

1. Early mammals were small like shrews
2. Persisted amongst the dominant dinosaurs without diversification into new lineages and niches
3. Evolved into many diverse lineages after extinction od the dinosaurs when niches became avaliable

Question 2

Modern Mammal Evolution Ideas (3):

Answer 2

Mammals started to diverge before the KT extinction and continued to diverge

Question 3

Living Groups of Mammals (3):

Answer 3

1. Monotremes
2. Metatheria (marsupials)
3. Eutheria (placentals)

Question 4

Mammal Characteristics (4):

Answer 4

1. Feed young milk secreted from mammary glands
2. Extended parental care of young
3. Large brain/body size ratio
4. hair (integumentary derivative)

Question 5

Modern Mammal Integument: Specialized Glands (2)

Answer 5

1. Sebaceoous Glands
2. Sweat glands

Question 6

Modern Mammal Integument: Specialized Glands (Subaceous Glands) (3)

Answer 6

• Alveolar glands
• Oily/waxy secretion often with hair
• Waterproof hair and protect skin from drying

Question 7

Modern Mammal Integument: Specialized Glands (Sweat Glands) (3)

Answer 7

• Tubular glands
• Secrete water, salts, urea
• Some important for thermoregulation

Question 8

Mammary Glands (Development, location, and function):

Answer 8

1. Develop from clumps of cells in the ectoderm during embryonic development
2. Number and location of nipples varies across species
3. Provide nutrition for young offspring

Question 9

Sweat Glands (Development, location, and function):

Answer 9

• Derived from sebaceous glands, and sweat glands
• Located on integument
• Defense, sexual selection

Question 10

Epidermal Derivatives in Mammals (4):

Answer 10

1. Claws, hooves and nails at the ends of digits
2. Horns (most not shed; keratin over bony cover)
3. Antlers (shed; mostly bone)
4. hair (thermoregulation and sensory organs)

Question 11

Dermal Derivatives in Mammals:

Answer 11

Osteoderms (only armadillos)

Question 12

What do Marsupials Do:

Answer 12

Give birth to tiny young who suckle until they grow much larger, often in a specialized pouch of the mother

Question 13

What are Placentals (Eutheria):

Answer 13

• Most diverse and widespread group of mammals
• Radiated extensively after the KT extinction
• Prolonged gestation of embryo in uterus with placenta

Question 14

How are Placentals (Eutheria) Distributed:

Answer 14

Correlate with isolation of continents as they drifted away from the earlier supercontinent (pangea)

Question 15

Marsupial Diversity:

Answer 15

• Became isolated after continental breakup
• Through convergent evolution

Question 16

Different Eutheria (Placental) Diversity (3):

Answer 16

1. Afrotheris (aardvarks, elephants, and some shrews - Africa)
2. Xenartha (armadillos, sloths, and anteaters (South America))
3. Euarchontoglires (treeshrews, colugos, primates, rabbits, and rodents)
4. Laruasiatheria (hedgehogs, shrews, moles, bats, dogs, cats, and hoofed animals (in all continents))