L 18 Biodiversity of Sarcopterygian fishes

Question 1

what are the sarcopterygii fishes?

Answer 1

lobe finned fishes

Question 2

What kind of scales do sarcopterygian fishes have?

Answer 2

cosmoid scale

Question 3

What are cosmoid scales like?

Answer 3

Consist of cosmine, overlain by thing hard layer of enamel and inner layer of spongy bone. Then a deep layer of lamellar bone.

Question 4

How are the fins of sarcopterygians different from actinopterygian fishes?

Answer 4

Sarcopterygians have two dorsal fins. Also have lobed fins.

Question 5

Sarcopterygian fishes are divided in what two groups?

Answer 5

1. Crossopterygians: the coelacanths

2. dipnoi : the lungfishes

Question 6

How are most crossopterygians usually characterized? (2)

Answer 6

1. Large tri lobed tail

2. intracranial joint

Question 7

What’s a diphycercal?

Answer 7

what a tri lobed tail is called.

It’s when a tail is flanked above and below by dorsal and ventral lobes

Question 8

What does a intracranial joint?

Answer 8

provides for cranial kinesis. It’s when dividsion of cranium that form anterior and posterior units that are part of a specialized feeding mechanism.

Question 9

3-6 characters of crossopterygians

Answer 9

3. lungs, represented by large fat filled sac
4. bone is much reduced
5. intestine with large, well developed spiral valve
6. osmoregulation by retention of urea

Question 10

How are modern lungfishes characterized?

Answer 10

1. well developed air breathing lungs
2. largely cartilaginous skeleton
   3 Inteneral nostrils
3. Large plate like teeth for crushing
4. spiral valve in the intestine

Question 11

who is Sir Richard Owen?

Answer 11

British paleontologist who first claimed that lungfishes gave rise to tetrapods

Question 12

Who is Edward Drinker Cope?

Answer 12

Proposed that crossopterygians are closely related to tetrapods

Question 13

Who is Donn E Rosen?

Answer 13

Said that lungfishes gave rise to tetrapods.

Question 14

What were the evidence provided for lungfish as the rise to tetrapods?

Answer 14

1. Internal Nostrils
2. tetrapod like limbs - primitive lungfishes have two primary joints in each paired appendage like tetrapods
3. tetrapod like locomotion

Question 15

What are some evidence that crossopterygians gave rise to tetrapods?

Answer 15

1. paired fins of certain extinct crossopterygians are more like tetrapod limbs than lungfish
2. most bones of crossopterygians can be homologized with those of labyrinthodonts
3. crossopterygians have specilized tooth struc in outer layer of enamel