Topic 7: Unikonts IV (Deuterostomes)

Question 1

What are the shared derived characteristics of the deuterostome clade?

Answer 1

radial, intermediate cleavage
coelom forms from archenteron
blastopore becomes anus

Question 2

What are the shared derived traits of the phylum chordata?

Answer 2

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

Question 3

What are the derived traits of vertebrates?

Answer 3

bone or cartilage vertebrae that replace notochord

2+ hox clusters

Question 4

How did vertebrates get more than 2 hox clusters? What is the advantage of this?

Answer 4

complete genome duplication

increased genetic complexity -> more complex body plan

Question 5

What is the basal vertebrate and it’s characteristic?

Answer 5

jawless fish

cartilage, not bone

Question 6

What is the SDTs of gnathostomes?

Answer 6

hinged jaw
bony skeleton
4 hox clusters

Question 7

What is the basal gnathostome? What characteristics do they have?

Answer 7

chondrichthyes - cartilanginous fish

bone only in teeth and fin scales

Question 8

What is the SDT of Osteichthyes?

Answer 8

Swim bladder (homologous with lungs)

Question 9

What is the basal clade of osteichthyes?

Answer 9

actinopterygii - ray finned fish

Question 10

What is the shared derived trait of lobe-fins?

Answer 10

muscular fins/limbs for locomotion

Question 11

What are the basal clades of lobe-fins?

Answer 11

actinistia

dipnoi

Question 12

What are the shared derived trait of tetrapods?

Answer 12

4 limbs with digits
neck
fused with pelvic girdle - efficiently transmits forces through body

Question 13

What are the basal tetrapods?

Answer 13

amphibia

Question 14

What are the SDTs of amniotes?

Answer 14

amniotic egg

ribcage ventilation

Question 15

What is an amnion?

Answer 15

membrane that forms fluid filled sac around embryo

Question 16

What are the derived traits of animals?

Answer 16

mammary glads
give birth to live young
hair, fat layer under skin -> retain heat

Question 17

What are the three groups of mammals?

Answer 17

monotremes
marsupials
eutherians

Question 18

What are the basal mammals?

Answer 18

monotremes

Question 19

What are the characteristics of monotremes?

Answer 19

lay eggs
have hair
produce milk, but no nipples

Question 20

What are the characteristics of marsupials?

Answer 20

give birth to live young

have nipples

Question 21

Define placenta

Answer 21

structure for nutrient exchange from mother to embryo

Question 22

What is the sister to eutherians?

Answer 22

marsupials

Question 23

What are the characteristics of eutherians?

Answer 23

complex placenta
longer pregnancy than marsupials
complete their embryonic development in uterus

Question 24

What are the derived traits of primates?

Answer 24

large brain, short jaws
grasping hands/feet
forward facing eyes
high parental care
complex social behavior
monkeys, apes - fully opposable thumb

Question 25

Define hominin

Answer 25

species on human “side” of human chimp divergence

Question 26

What is the only extant hominin?

Answer 26

homo sapiens

Question 27

What are the characteristics of modern humans?

Answer 27

bigger brains (than other hominins)
complex tools
fully bipedal traits
small jaw, "short" digestive system
language and symbolic thought