Lesson 5 Flashcards

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1
Q

origin of jaws

A

number one most important evolution in vertebrate history

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2
Q

uses of jaws

A
  • can facilitate breathing
  • grasping prey
  • chewing food - breaking it into tiny particles
  • defense
  • manipulating things
  • movement of vocal tract
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3
Q

earliest existance of vertebrates

A

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

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4
Q

clues that the moyllokunminga was a vertebrae

A
  • 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
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5
Q

conodonts

A
  • 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
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6
Q

environment during early vertebrate evolution (an abundance of extractoderms)

A

jawless forms of osteognathostomes

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7
Q

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

A
  • 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
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8
Q

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

A

true?

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9
Q

deuterostomes

A

anus forming before mouth

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10
Q

collecting evidence for marine animals coming first

!!!!!

A
  • 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
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11
Q

agnathans

A
  • jawless vertebates
  • lack jaws and 2 sets of faired fins
  • lack specilized reproductive groups
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12
Q

hagfishes

A
  • 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
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13
Q

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

A
  • gets a hold of the flesh and ties its posterior region in a knot
  • tightening of knot helps to tear off fish
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14
Q

hagfish slime

A

glands - predtor deterrent

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15
Q

hagfish populaiton

A

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

unfortunately humans are hurting hagfish – eel skin

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16
Q

lamprey

A
  • 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
17
Q

how are lamprey similar to salmon

A
  • ascent freshater streams to spawn and breed
  • young lamprey will swim out to the salt water
  • anadromous (like salmon )
18
Q

anadromous

A

migrating up rivers to spawn

19
Q

lamprey (title ventilation)

A
  • 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
20
Q

what might have driven extractoderm to extinction

A
  • 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
21
Q

how did jaws evolve

A

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

22
Q

what did the 2nd gill become

A

hyoid arch

23
Q

nostril

A
  • 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
24
Q

in a single nostril

A

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

25
Q

because of the presence of jaws, organisms have

A
  • a true stomach
  • a more complex rib
  • distinct pancreas
26
Q

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

A
  • 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
27
Q

origin of fins

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