Slides 28

Question 1

derived characters of chordates

Answer 1

notochord, dorsal hollow nerve chord, pharyngeal slits, muscular post anal tail; resembled lancelets who retain all traits as adults

Question 2

derived vertebrate characters

Answer 2

neural crest appears along the edges of the closing neural tube; disperse through embryo and give rise to: teeth, bone and cartilage of skull, neurons, sensory capsules

Question 3

lampreys

Answer 3

living lineage of vertebrates that represent early evolving; jawless, reduced vertebrae, notochord, cartilaginous skeleton

Question 4

gnathostomes

Answer 4

have jaws with teeth used to grip and slice food, jaws evolved by modification of skeletal rods supporting pharyngeal slits (gills)

Question 5

early gnathostomes

Answer 5

440 million years ago, adaptations improved: paired fins and a tail; dorsal, ventral, and anal fins stiffened by bony fin rays; efficient gas exchange system in the gills

Question 6

gnathostome divergence

Answer 6

3 lineages, chondrichthyans, ray-finned fishes, lobe-fins

Question 7

chondrichthyans

Answer 7

skeleton composed primarily of cartilage, often impregnated with calcium; traces of bone found in scales, at base of teeth, coating vertebrae, bone evolved AFTER

Question 8

ray-finned fish and lobe-fish

Answer 8

most vertebrates are osteichthyans and have bony endoskeleton; include bony fish and tetrapods; aquatic are fishes

Question 9

fish innovations

Answer 9

gills of fishes protected by a bony flap called operculum; water drawn into mouth and over gills by muscle contractions and movement of the operculum; air sac called swim bladder for buoyancy

Question 10

ray-finned fishes (actinopterygii)

Answer 10

27,000 species, originated during Sillurian period; modifications in body form and fin structure affect maneuvering, defense, and other functions

Question 11

lobe-fins (sarcopterygii)

Answer 11

Silurian period; pectoral and pelvic fins have rod-shaped bones surrounded by a thick layer of muscle; only 3 remaining lineages: coelacanths, lungfishes, tetrapods

Question 12

lungfish

Answer 12

3 species in southern hemisphere; live in ponds and swamps now; gas exchange occurs in water using gills

Question 13

tetrapod evolution

Answer 13

fins evolved into limbs 365 million years ago; diversified following evolution of limbs and colonization of land

Question 14

tetrapod derived characters

Answer 14

“four feet” body plan; four limbs with feet and digits; a neck that enables independent movement of head; fusion of pelvic girdle to backbone; absence of gills; ears for detecting airborne sounds

Question 15

amphibians

Answer 15

6,150 species in 3 clades: salamanders, frogs, caecilians

Question 16

lifestyle and ecology of amphibians

Answer 16

larvae are aquatic with gills, lateral line system, long finned tail; during metamorphosis develop terrestrial features legs, lungs, and external eardrums and adjust to carnivore diet

Question 17

amphibian eggs

Answer 17

lack a shell and must be laid in water or moist environments on land; fertilization is external; some lay many unprotected; some lay few and protect by carrying on back/mouth/stomach

Question 18

derived characters of amniotes

Answer 18

amniote egg which contains four membranes that protect the embryo; reduced dependence on water for reproduction; 4 membranes: amnion, chorion, yolk sac, allantois

Question 19

extraembryonic membranes

Answer 19

amnion: protects embryo, fluid-filled cavity that cushions against shock; yolk sac: stockpile of nutrient; allantois: disposal sac for embryonic waste; chorion: exchange gasses between embryo and air

Question 20

amniote diversity

Answer 20

tetrapods whose living members are reptiles and mammals

Question 21

early amniotes

Answer 21

350 million years ago, early lived in warm moist areas but expanded over time, predators that resembled small lizards with sharp teeth

Question 22

reptiles

Answer 22

scales: containing keratin to protect skin from desiccation and abrasion; shelled eggs; fertilization occurs internally before shell is secreted

Question 23

reptile- diapsids

Answer 23

earliest reptiles resembled lizards, main lineages: turtles, lepidosaurs (lizards, snakes, dead mososaurs), archosaurs (birds, crocodiles, dead dinosaurs)

Question 24

turtles

Answer 24

lost holes in skulls, boxlike shell made of upper and lower shields fused to the vertebrae, clavicles, ribs acquired over stages in evolution

Question 25

snakes

Answer 25

descended from lizards with legs with vestigial pelvic and limb bones, move on land by producing waves of lateral bending from head to toe, easily use belly to grip ground at several points to pull body forward

Question 26

archosaurs- birds

Answer 26

evolved extensive modifications; weight-saving modifications to improve efficiency of flight; no urinary bladder, only one ovary, small gonads, toothless mouths, bones with honeycombed internal structure

Question 27

origin of birds

Answer 27

belong to group of bipedal dinosaurs called theropods; feathers evolved before powered flight for camouflage, insulation, courtship; archaeopteryx earliest bird with feathered wings but teeth claws and long tail ancestral features