Lesson 8 -- Sarcopterygii (lobe finned fishes)

Question 1

tetropodomorph

Answer 1

• almost perfect fossil found in quebec –> doesnt mean that that was there the aninal lived –> land was constantly moving

Question 2

coelacanthiformes

Answer 2

• long hisotry
• deep into the devonian
• come to an abrupt hault 66 million years ago
• knew that colecanths were hugely represented in the fossil record
  – all come to an end –> no colecanths from rocks that were younger than that
  – paleoenthiligical scientist on holiday – finds a freshly killed colecanth
• these things persist but they are just very good at hinding
• 2nd species discovered on coast of indonesia

Question 3

characteristics of coleacanth

Answer 3

• have a unique electroreceptive system
  -paired fins
• anal and second dorsal fin
• osmolality of their blood is very close to sea water –> kind of like chondrithyea
• give live births to adult looking pups
• don’t know how they accomplish internal fertilization because there is no “penis”
• do not do well in captivity
• have an intrarcranial joint
  ^^^^ only extant vertebrate with this kind of joint

Question 4

ceolocants

Answer 4

• some quite enormous fihses
• move their fins in diagonal oaurs

Question 5

lungfish

Answer 5

freshwater fish that belong to dipnoan

Question 6

dipnoans

Answer 6

• lack an articulated and toothbearing premaxillary and mandible
• all extant are freshwater
• skeletons are mostly cartilagenous
  — but hightly mineralized
  — pedomorphic traits
  — all have this fused dorsal/caudal/anal fin
  ^^^ as the embryo develops, they reatin this lack of separation among fins

Question 7

pedomorphic traits

Answer 7

——-traits retained into adulthood that have a juvenile like trait
in HUMANS –> babies have large heads and so do adults

Question 8

austrailian lungfush

Answer 8

• almost uses its gills entirely for ventilation
• no parental care after spawning
• intense male courtship

Question 9

south american lungfish

Answer 9

• an obligate air breather
• has to use its lungs to survive
• comes to the surface and gulps down air to survive

Question 10

African lungfish

Answer 10

• uses lungs to take on oxygen
• but uses gills to filter out CO2
• in seasonal times where their water disappears
  — they bury into the mud and lower their metabolic rate
  — period of dormacy
  — come out after the rains come
  — behavior is known to be quite ancient

Question 11

tetropodomorph

Answer 11

• derived tetrapod fishes have most of the derived skeleton that we have today
• shows how close we are to these other forms of sarcopteriggi

Question 12

tikaalik

Answer 12

• from the late denovian
• “fishopod”
• number of traits you would find in both fish like and tetrapod like

Question 13

tetrapods (Ichthyostega)

Answer 13

• ear region for underwater hearing
• paddle like hindlimbs – suggest aquatic
• forelimbs didn’t evolve (or somehow was cut off)

Question 14

denovian tetrapod

Answer 14

presence of zigapophysis –> make vertebral column much more resistant for torsion – -good for resistance to gravity

Question 15

not quite a denovian tetrapod

Answer 15

pelvic fin

Question 16

earliest tetrapods are thought to be aquatic

Answer 16

REASON
- some traits sugest awuatic respiratio
- reveal a groove on the vental cerobranchial that supports the gills
- in extant fish – that particulat groove carries an artery to the gills, MEANING that it is involved in carrying oxygenated blood
- presence of ridge suggests presence of gills - hence - aquatic

Question 17

pentalotists

Answer 17

5 fingers on limbs

Question 18

polydactery

Answer 18

more than 5 digits

Question 19

what sort of change occured between