Lec 4 Sarcop & Early Terrestrial Verte

Question 1

What are the 3 Sarcopterygian groups?

Answer 1

Actinistia, Dipnomorpha, Tetrapodomorpha

Question 2

When is Sarcopterygian originated?

Answer 2

Silurian

Question 3

What are the features of Sarcopterygian?

Answer 3

1. lobed fins
2. 1 main bone proximally that forms joint with girdles
3. 2 dorsal fins
4. cosmoid scales
5. diphycercal tail
6. intercranial joint

Question 4

What are the characteristics of Coelacanths?

Answer 4

usual stuff: diphycercal tail, 2 dorsal fins, lobed fins

midline fins

Question 5

What are the characteristics of Lungfish?

Answer 5

1. Symmetrical array of supports in fins
2. Loss of marginal tooth bearin elements and skull roof elements
3. nostrils both inside oral cavity
4. triangular, crushing tooth plate

Question 6

What is used to describe Sarcopterygian with limbs with digits?

Answer 6

Stegocephalia

Question 7

What are the features of Tetrapodomorpha?

Answer 7

Choana, 1 proximal radial and 2 radials, mandibular fossa, contact b/w otic and supraorbital canals

Question 8

When is the critical period for fin-to-limb transition?

Answer 8

Late Devonian

Question 9

What are the groups involved in fin-to-limb transition?

Answer 9

Eusthenopteron, Panderichthys, Tiktaalik, Acanthostega, Ichthyostega, Dendrerpeton

Question 10

Anatomical changes in fin-to-limb transition?
Head

Answer 10

1. longer snout, skull shorter behind orbits
2. orbits back and more dorsal
3. Hyomanidbula shorten and oriented laterally

Question 11

Anatomical changes in fin-to-limb transition?
Neck region

Answer 11

1. Loss of opercular bones
2. Loss of extrascapular and supracleithrum
3. Gular elements reduced
4. gill regions reduced and missing
5. Cleithrum reduced
6. Capulocoracoid and interclavicle increase!
7. girdle decouple from skull -> neck

Question 12

Anatomical changes in fin-to-limb transition?
Limbs

Answer 12

Longer limbs, stouter, more separate
Digits (carpals, tarsals)
articular surfaces -> greater range of motion

Question 13

Anatomical changes in fin-to-limb transition?
Body and fins

Answer 13

tail elongated
flattened body
missing anal and dorsal fins

Question 14

Purpose of internal choana in fishes

Answer 14

Create a water current without having to move -> smell -> ambush prey

Question 15

Why early tetrapodomorpha went onto land

Answer 15

a) temp
b) O2
c) avoid predators
d) repro
e) unexploited food sources

Question 16

When did fully terrestrial vertebrates evolve?

Answer 16

Carboniferous

Question 17

What are some terrestrial features in later tetrapodomorpha?

Answer 17

robust pelvic girdle and limbs
pentadactyl pes
metatarsals distinct from phalanges
digits face forward, not laterally
hook-like process on humerus for latissimus dorsi