Sarcopterygians

Question 1

3 genera of lungfish are?

Answer 1

1. Australian group - well-developed fins, scales and gills
   •primarily relies on gills - found in permanent bodies of water
2. African and South American group - need lung, used more
   •fins reduced, pelvic used for moving (walking or running motions)
   •found in temporary water bodies - not much known
3. African group
   •water falls, lungfish burrows self into mud
   •cover itself in tail and mucous - leaves hole for breathing
   •stays like this till water returns = potentially years

Question 2

Coelacanths

Answer 2

•thought to have gone extinct 80mya
-one was found in by-catch
•found in deep sea and are large bodied
•don’t use fins for walking on - but move in similar undulating way to tetrapods
•have a lung (ancestral bony fish feature)
-filled with fat and acts like liver of cartilaginous fishes

Question 3

Tetrapodomorph fishes and tetrapods

Answer 3

Gave rise to tetrapods:
1. Osteolepiforms - large bodied fishes, lived in shallow waters and were ambush predators
2. Panderichthyes - more derived
Sudden jump to tetrapods that dates back to 365mya
3. Acanthostega and Ichthyostega
Then a missing link was found
4. Tiktaalik - from 383mya

Question 4

Panderichthyes features

Answer 4

•large bodied but different shapes
•head is more elongated with eyes at top of head
•lost dorsal and anal fin, coral fin very reduced
•ribs more extensive and point downwards - previously pointed upwards and smaller
•fins are crop-like - especially pectorals, may have used to prop selves up
•spiracular region (remnants of gill chamber) completely different in this group
-looks like beginnings of tetrapod middle ear