Lecture 24

Question 1

synapsids

Answer 1

one hole in skull, all non-mammalian members extinct, includes sailbacks and therapsida (mammals), sprawling reptile-like gait, most predatory

Question 2

Dimetrodon

Answer 2

sailback synapsid

Question 3

therapsids

Answer 3

1. enlarged dentary bone in jaw
2. development of secondary palate (shelf of bone between mouth and nasal chamber, allows chewing and breathing at same time)

Question 4

Class Mammalia

Answer 4

1. leftover jaw bones move to middle ear
2. dentition much more differentiated than reptile dentition (greater diversity of tooth form due to greater diversity of diet)
3. teeth occlude more closely than reptiles (grind food finely, greater surface area to extract nutrients faster)
4. two sets of teeth (milk and adult)
5. more vertical position of limbs beneath body (more efficient movement)
6. hair (fine cylindrical keratin fibres)
7. endothermic and homeothermic
8. diaphragm (sheet of muscle at base of ribcage to help with breathing)
9. mammary glands (glands that secrete nutritious fluid
   to feed offspring)

Question 5

3 major clades of extant mammals

Answer 5

1. order monotremata
2. order marsupiala
3. clade eutheria

Question 6

origin of mammals

Answer 6

present at end of Cretaceous, diversified after mass extinction event

Question 7

order monotremata

Answer 7

platypus and echidna, lay eggs (oviparous) but provide milk after hatching, cloacas

Question 8

theria

Answer 8

includes marsupials and eutherians, young initially nourished via placenta, after birth nursed on milk from nipples

Question 9

placenta

Answer 9

extraembryonic membranes + lining of the uterus, transfers nutrients and oxygen from mother’s blood to embryo’s blood

Question 10

nipples

Answer 10

conical outlets to milk glands

Question 11

order marsupiala

Answer 11

born as partially developed embryo that crawls to mother’s pouch, cloaca

Question 12

eutheria

Answer 12

non-marsupial therians, nourish young via placenta until very well-developed, number of nipples indicative of number of offspring born at a time, no cloaca

Question 13

4 clades of eutherians

Answer 13

1. afrotheria
2. xenarthra
3. laurasiatheria
4. euarchontoglires

Question 14

afrotheria

Answer 14

elephants, hyraxes, manatees, aardvarks, and elephant shrews, underwent diversification in Africa

Question 15

xenarthra

Answer 15

anteaters, sloths, armadillos, lack teeth, extra articulations in vertebrae

Question 16

laurasiatheria

Answer 16

origin laurasia (europe asia and north america), includes order carnivora, order chiroptera, Cetartiodactyla (even-toed hoofed mammals and dolphins/whales/porpoises mammals), order perissodactyla (odd-toed hoofed mammals)

Question 17

order chiroptera

Answer 17

bats, only mammals capable of powered flight, use sonar to augment sight

Question 18

white nose disease

Answer 18

fungal disease devastating bat colonies in north america

Question 19

euarchontoglires

Answer 19

glires subclade
1. order lagomorpha (rabbits, hairs, pikas)
2. order rodentia (largest order of mammals, constantly growing front teeth)
euarchonta subclade
1. order scandentia (tree shrews)
2. order primates