Sarcopterygii (lobe-fin fishes)

Question 1

What are the 3 major lineages of Sarcopterygii?

Answer 1

Actinistia
Dipnoi
Tetrapodomorpha

Question 2

What is an example of an Actinistia?

Answer 2

Coelacanths

Question 3

Where do Coelacanths live?

Answer 3

deep-marine - in steep underwater cliffs

Question 4

What is there caudal tail like in coelacanths?

Answer 4

3-lobed fin

Question 5

Where are pectorals and pelvic fins located?

Answer 5

low below body (not on the side like in ray-fin fishes)

Question 6

How do Coelacanths move their pectoral and pelvic fins?

Answer 6

for propulsion they move in opposite pairs (diagonal pelvic and pectoral fin pairings) more like how tetrapod’s move

Question 7

What do Coelacanths do that sharks do? (evolved separately)

Answer 7

retain urea to balance molarity

Question 8

How do Coelacanths give birth?

Answer 8

to live young

Question 9

What is the Intercranial hinge?

Answer 9

cranium is in two parts - so the whole top of head is hinged
small brain mostly in front with notochord that swells and inhibits brain development

Question 10

What does the intercranial hinge possibly allow for?

Answer 10

increased bite force
or improved suction feeding by raising roof of mouth

Question 11

What is unique about the nasal openings of Coelacanths?

Answer 11

they have 2 external openings (so 4 nostrils)

Question 12

What does 2 nasal openings allow for in Coelacanths?

Answer 12

a nsal passageway (incurrent and excurrent nostril) water through incurrent out excurrent for chemoreception

Question 13

What are nostrils called?

Answer 13

Choanae

Question 14

What is a character about Coelacanths fin spines?

Answer 14

they are hollow

Question 15

What is an adaptation of the Coelacanth swim bladder?

Answer 15

it is filled with lipids that provide buoyancy (but no longer used fro gas exchange)

Question 16

What is a type of Dipnoi?

Answer 16

Lungfish

Question 17

WHat type of lungs do lungfish have?

Answer 17

paired lungs

Question 18

What is pectoral fin like in South American and South African lungfish?

Answer 18

small - thin vein like

Question 19

WHat is caudal fin like in all lungfish?

Answer 19

no longer heterocercal but dorsal, anal, and caudal fin are fused together

Question 20

What is a dentary adaptation of lungfish?

Answer 20

loss of all tooth bearing bones, just palentine and some dermal bones left creates a flat plate that crush together
feed on shells of mollusks and hard shell invertebrates

Question 21

What is signbificant about genome of lungfish?

Answer 21

it is the largest vertebrate genome

Question 22

What is a character that first appears in lungfish?

Answer 22

a heart with a divided atrium

Question 22

Where are the choanae in lungfish found?

Answer 22

upper lip

Question 23

What happens as we move towards tetrapods?

Answer 23

loss of cosmine scales
and excurrent choanae move towards the mouth

Question 24

What are features that partly distinguish Sarcopterygii?

Answer 24

monobasic muscular limbs origins of1 bone - 2 bone pattern (cosmine scales)

Question 25

What are the subgroups under Tetrapodamorpha?

Answer 25

Tetrapoda - "stem tetrapods" and crown tetrapods Tetrapodamorpha fish - including Tiktaalik

Question 26

What becomes clear within tetrapodomorpha?

Answer 26

the 1-bone-2-bone pattern

Question 27

What are features that develop between dipnoi and tetrapodomorpha?

Answer 27

choanae - one external one in mouth single basal limb bone loss of operculum bone increase size of pelvic girdle increase thickness of ribs radials to distinct wrist wrist, neck, and elbow flexion

Question 28

What are features that developed after tetrapodomorpha fish?

Answer 28

digits - fin rays lost zygapophyses on vertebrae ohecranon process (funny bone) loss of dorsal fins loss of cosmine scales

Question 29

How did the tetrapodomorpha fish limbs likely evolve?

Answer 29

in shallow waters

Question 30

What did Tiktaalik not develop that helps with movement on land?

Answer 30

no ischium no ohecranon proceess (funny bone)

Question 31

What are 'the stegas'?

Answer 31

acanthostega ichthyostega tulekpetan

Question 32

What are features of the ichthyostega?

Answer 32

pelvic girdle attached to sacral vertebrae 7-8 digits, polydactyl flat tails good for swimming still had internal gills paddle shaped limbs - angled back, front limbs forward

Question 33

What are features of the Tulekpetan?

Answer 33

limbs move under body for support, push up tail for aquatic repulsion only

Question 34

Why did 'the stegas' move to land?

Answer 34

drying up shallow waters to move to other water sources Oxygen on land is easier to use

Question 35

What are trends across the stegas?

Answer 35

decrease in gills pectoral girdle is free parallel improvement in respiration pump CO2 out and buffer against acidosis with Ca Gas exchange across the skin with environment