Lesson 5

Question 1

origin of jaws

Answer 1

number one most important evolution in vertebrate history

Question 2

uses of jaws

Answer 2

• can facilitate breathing
• grasping prey
• chewing food - breaking it into tiny particles
• defense
• manipulating things
• movement of vocal tract

Question 3

earliest existance of vertebrates

Answer 3

myllokunminga
- from early cambrian
- dorsal fin is more derived than the dorsal fin in lamprey
- know that the fossil has a notochord so it is at least a chordate

Question 4

clues that the moyllokunminga was a vertebrae

Answer 4

• paired sensory structures in the head
• can infer from ^^^ that it had a neural crest
• ^^ can’t see the neural crest cells - can infer based on paired sensory structures and the cranium
• W shaped myomeres

Question 5

conodonts

Answer 5

• not sure where they branch off from
• not sure if they broke off before the cyclosomes or not - about 4 cm long
• extinct
• lack pharyngeal slits
• myomeres have V shape, not W shape

Question 6

environment during early vertebrate evolution (an abundance of extractoderms)

Answer 6

jawless forms of osteognathostomes

Question 7

environment during early vertebrate evolution (mor likely to be freshwater or marine)

Answer 7

• vast majority of experts feel most likely from marine origins
• earliest fossil from marine deposits
• earliest known specimiens are all in marine deposits
• all invertebrates, chordates, as well as all deuterstomes that are not vertebrate are marine

Question 8

t/f: all extant deuterostomes except the vertebrates are marine

Answer 8

true?

Question 9

deuterostomes

Answer 9

anus forming before mouth

Question 10

collecting evidence for marine animals coming first

!!!!!

Answer 10

• the ability of the modern kidney to excrete excess water
• the need to do so would be more important for a saltwater organisms
• suggesting that it is very old because the kidney is amazing at what it does

Question 11

agnathans

Answer 11

• jawless vertebates
• lack jaws and 2 sets of faired fins
• lack specilized reproductive groups

Question 12

hagfishes

Answer 12

• do have neural crests
• distributed worldwide
• marine
• deep sea dwelling
• often found in cold water
• individuals are not wide ranging –> live and breath very locally
• range –> singal individual
• disribution –> hagfishes as a group
• scavangers
• ## very good olfaction for detecting dead things

Question 13

if hagfishes have no jaws, how will they bite dead animals

Answer 13

• gets a hold of the flesh and ties its posterior region in a knot
• tightening of knot helps to tear off fish

Question 14

hagfish slime

Answer 14

glands - predtor deterrent

Question 15

hagfish populaiton

Answer 15

sex ration of 100 females to 1 male
- might be hermaphroditic

unfortunately humans are hurting hagfish – eel skin

Question 16

lamprey

Answer 16

• about 40 species, 2 genus
• most are parasitic on other animals
• attaches to a live fish and feed off its blood – secrets an anticoagulant so the blood doesn’t stop flowing
• found in many types of salinites

Question 17

how are lamprey similar to salmon

Answer 17

• ascent freshater streams to spawn and breed
• young lamprey will swim out to the salt water
• anadromous (like salmon )

Question 18

anadromous

Answer 18

migrating up rivers to spawn

Question 19

lamprey (title ventilation)

Answer 19

• spend a lot of time in suction
• how will it ventiliate if it cannot open its mouth to breathe?
• doesn’t have flow through ventilation —–> have title ventilation
  MEANING
• almost like the flow of air in out lungs
• blind respiratory tube
• water is pumped through the gills – gas exchange occurs – then it is pumped back through the gills

Question 20

what might have driven extractoderm to extinction

Answer 20

• never evolved jaws – were simply outcompeted by those with jaws
• if you look at phylogeny dats – notice that extracoderms coxisted with jawed fish for a pretty long time so notion has casted doubt on the previous hypothesis^^
• new ONE –> sea levels lowering and loss of habitat that extractoderms perferred
• obligates of coastal marine habitat

Question 21

how did jaws evolve

Answer 21

evolved out of gill arches (we think)
- look at ancestral agnathous (jawless) - gnathostome look very similar – looks as though the first gill arch formed mandible and upper jaw

Question 22

what did the 2nd gill become

Answer 22

hyoid arch

Question 23

nostril

Answer 23

• presence of single nostril instead of 2 might have played a very evolutionary role in the formation of jaws
• anterior position of nasal placodes
• in jawed organisms - are anterior to () which leave space for neural crest cells

Question 24

in a single nostril

Answer 24

there is no room for the neural crest cells to go to form the jaws

Question 25

because of the presence of jaws, organisms have

Answer 25

• a true stomach
• a more complex rib
• distinct pancreas

Question 26

why is having a true stomach, more complex rib, and a distinct pancrease associated with having jaws

Answer 26

• jaws open up many opportunitis –> diet choices
• paved the way for a more active lifestyle that required more energy
• NEED to FUEL
• a more complex skeleton is needed to sustain a more comlpex lifestyle

Question 27

origin of fins

Answer 27

• acanthodians had structures similar to fins that aided in the movements of pitch, roll, and yaw