Mammals

Question 1

What major group of amniotes is the first to diversify widely to terrestrial habitats?

Answer 1

Synapsids

Question 2

What is pelycosaurs?

Answer 2

Earliest synapsids diversified into diverse herbivores and carnivores

Question 3

What are Therapsids?

Answer 3

Arose from early carnivorous pelycosaur group
More efficient upright gait
Skulls indicate more efficient feeding and muscular co-ordination
Hard palate partially separated the nasal and oral cavities

Question 4

What is the one therapsid group that survived to Mesozoic era?

Answer 4

Cynodonts

Question 5

Cynodonts features

Answer 5

Show features supporting higher metabolic rate:
Jaw musculature for stronger bite
Heterodont teeth
Turbinate bones – retention of body heat
Secondary palate
Loss of lumbar ribs and evolution of diaphragm as well as greater flexibility of spine

Question 6

What are the Major characteristics of modern mammals?

Answer 6

Hair (and integumentary glands)
Mammary glands
Specialized teeth
3 middle ear ossicles
Endothermy

Question 7

What are the two lineages of living mammals?

Answer 7

-Subclass Prototheria
—–Infraclass – Ornithodelphia

-Subclass Theria
Infraclasses:
—–Metatheria
—–Eutheria

Question 8

Unlike other mammals Monotremes:

Answer 8

-Have a cloaca
-Are oviparous

Question 9

Describe Infraclass Metatheria
Marsupials

Answer 9

-Viviparous but have short gestation periods
-Have marsupium (pouch) covering female mammary glands

Question 10

Describe Infraclass Eutheria
Placental mammals

Answer 10

-Nourished within uterus via placenta
-Born at advanced stage of development

Question 11

Functions of hair in Mammals

Answer 11

-insulation
-touch
-protection

Question 12

What occur over most of body of most mammals; absent from other vertebrates?

Answer 12

Sweat glands

Question 13

What are the four classes of glands?

Answer 13

sweat, scent, sebaceous and mammary

Question 14

What are the functions of Eccrine glands?

Answer 14

-Secrete watery fluid
Evaporation; cooling
Occur in hairless regions – foot pads
All over body in horses and primates
Reduced/absent in rodents, rabbits and whales

Question 15

What are the functions of Apocrine glands?

Answer 15

-Secrete milky fluid
Always open into hair follicle
Develop around puberty
Secretions dry on skin; form film
Involved in reproductive cycle not heat regulation

Question 16

What are the functions of Scent glands?

Answer 16

Location and function variable
Conspecific communication
Territorial marking
Warning
Defense

Question 17

What are the functions of Sebaceous glands?

Answer 17

Usually associated with hair follicles but some just open to surface of skin
Secrete greasy sebum
Keeps skin and hair pliable and glossy
Most mammals have these glands over entire body

Question 18

What are the functions of Mammary glands?

Answer 18

Occur on all female mammals; rudimentary in all males
Increase in size at maturity and become larger during pregnancy and nursing
In humans adipose deposits around mammary glands to form breast

Question 19

Why is it that the smaller the mammal the greater its metabolic rate?

Answer 19

Metabolic rate of mammal varies according to relative surface area rather than body weight.
-Surface area is proportional to about 0.7 power of body weight
so the amount of food a mammal or bird eats is also about 0.7 power of its body weight to meet its metabolic needs

Question 20

Flight and echolocation allows bats to?

Answer 20

navigate in the dark
avoid obstacles
inhabit deep caves not exploited by other creatures

Question 21

Explain echolocation in bats

Answer 21

External ears of bats are large with variable shapes to focus in on the location of a sound
Bats can build a mental image of the surroundings via echo scanning that is similar to visual images by other animals

Question 22

High metabolic rates require adaptations for efficient gas exchange:

Answer 22

-Separate nasal and oral cavities and longer snouts
-Highly branched respiratory passages
-Negative pressure mechanism for inflation
-Muscular diaphragm