tetrapod origin

Question 1

what is an osteichthyan?

Answer 1

they contain a bony operculum-gill cover

endochondral bone
sung or swim bladder

Question 2

what is an octinopterygian?

Answer 2

has a single dorsal fin

Question 3

what are most basal living actinopterygians called?

Answer 3

birchirs:
polypterus bichir

does have a single dorsal fin but does not have reduced basals in fin skeleton

Question 4

how are actinopterygians - sturgeons so buoyant?

Answer 4

due to swim bladder - instead of lungs, it has a gas filled bladder

pneumatic duct connects to the gut

inflated by gulping air at the surface

helps with buoyancy

Question 5

what are living sarcopterygians?

Answer 5

2 species of coelacanths

6 species of lungfish

Question 6

how do lung fish breathe?

Answer 6

lungs extend from ventral gut (as in bichirs)
only Australian species also hava functioning lungs

Question 7

what are sarcopterygian tetrapods?

Answer 7

oldest evidence of tetrapods walking on land

due to shallow marine tidal flats

trackway varies in size