Chapter 34: Vertebrate Evolution

Question 1

synapomorphies of chordates

Answer 1

notochord, hollow dorsal nerve cord, pharyngeal slits, post-anal tail

Question 2

notochord

Answer 2

long, flexible rod of cells; provides skeletal support

Question 3

pharyngeal slits

Answer 3

posterior to mouth; suspension feeding; modifies into gills, jaws, etc.

Question 4

post-anal tail

Answer 4

muscular tail extends past anus

Question 5

lancets (cephalochordata)

Answer 5

invertebrate chordate; capable of swimming and live partially buried

Question 6

tunicates (urochordata)

Answer 6

chordate traits present in larvae; sedentary suspension feeders

Question 7

important innovations in chordate evolution

Answer 7

notochord, head, vertebrae, jaws, mineralized skeleton, lungs/swim-bladders, lobed fins/appendages, legs, amniotic egg, milk

Question 8

head

Answer 8

anterior brain and sensory organs with a skull; allow vertebrates to be more active

Question 9

cyclostomes

Answer 9

clade of jawless vertebrates including hagfish and lampreys

Question 10

gnathostomes

Answer 10

vertebrates with jaws; evolved from skeletal supports between gill slits. Lateral line system to sense vibrations in water

Question 11

clades of gnathostomes

Answer 11

chondrichthyes and osteichthyes

Question 12

osteichthyes

Answer 12

“bony fish”; gnathostomes with lungs (modified into swim bladder for most fish)

Question 13

clades of osteichthyes

Answer 13

actinopterygii and sarcopterygii

Question 14

sarcopterygians

Answer 14

osteichthyans with 4 appendages

Question 15

lobe-fins

Answer 15

pectoral and pelvic fins with rod-shaped bones surrounded by muscles; provide support for “walking” in the shallows

Question 16

clades of sarcopterygians

Answer 16

actinistia, dipnoi, and tetrapods

Question 17

tetrapods

Answer 17

sarcopterygians with legs; support for locomotion on land

Question 18

amphibians

Answer 18

oldest tetrapod lineage; lives on land and in water

Question 19

orders of amphibians

Answer 19

urodela, anura, apoda

Question 20

tadpole

Answer 20

aquatic larval stage of amphibians; metamorphosis to terrestrial adult

Question 21

amphibian eggs

Answer 21

eggs dry out quickly; must be wet or at least moist. External fertilization

Question 22

amniotic egg

Answer 22

allowed tetrapods to get fully on to land; four membranes and a shell

Question 23

amniotic egg membranes

Answer 23

amnion, chorion, yolk sac, allantois (plus shell and albumen)

Question 24

clades of amniotes

Answer 24

diapsida and synapsida

Question 25

reptiles

Answer 25

paraphyletic group; hard keratin scales, oviparous (lay shelled eggs on land), ectothermic

Question 26

lepidosaurs

Answer 26

lizards, snakes and tuataras

Question 27

tuataras

Answer 27

2 species on islands around new zealand

Question 28

squamates

Answer 28

lizards and snakes

Question 29

archosaur clades

Answer 29

crocodillians, birds/dinosaurs

Question 30

major lineages of dinosaurs

Answer 30

omithischian: “bird-hipped”
saurishian: “lizard-hipped”

Question 31

birds

Answer 31

evolved from theropods

Question 32

modifications for flight

Answer 32

keratin feathers evolved before flight; endothermic, no bladder, small gonads, air-filled bones, reduced weight

Question 33

flightless bird taxa

Answer 33

ratites: ostrich, emu, rhea
penguins: includes some ducks, etc.

Question 34

mammal characteristics

Answer 34

mammary glands: produce milk
hair and subcutaneous fat: retain endothermic heat
bones of jaws modified to be part of middle ear
differentiated teeth

Question 35

major clades of mammals

Answer 35

monotremes: egg laying mammals; no nipples
marsupials: mammals with a pouch
eutherians: placental mammals

Question 36

trait of primates

Answer 36

hands and feet for grasping, flat nails, fingerprint ridges, short jaw, forward looking eyes, large brain

Question 37

arthropoids

Answer 37

monkeys & apes; opposable thumbs

Question 38

hominims

Answer 38

extinct species that are more closely related to humans than to chimpanzees; diverged from a common ancestor

Question 39

paleoanthropology

Answer 39

study of human origins

Question 40

australopiths

Answer 40

early branch of hominin evolution

Question 41

bipedalism

Answer 41

walking on two legs

Question 42

tool use

Answer 42

other apes make simple tools; rocks, sticks, etc