Appendicular Skeleton

Question 1

Pelvic girdle attachment in osteichthyes

Answer 1

Suspended

Question 2

Describe limb movement in jumping

Answer 2

Hindlimbs extend rapidly to launch into air, forelimbs extend to cushion landing

Question 3

Type of joint between pelvic girdle & hind limbs of tetrapods

Answer 3

Ball and socket (allows wide range of motion)

Question 4

Effect of sprawled posture on girdles

Answer 4

Forces go up and in (medial), so large ventral girdle bones

Question 5

Girdle composition in chondrichthyes

Answer 5

Cartilage

Question 6

Pelvic girdle attachment in chondrichthyes

Answer 6

Suspended

Question 7

Changes from sarcopterygiian to tetrapod girdles

Answer 7

1. Became stronger, more completely ossified
2. Thin fin rays -> thick digits
3. Pectoral girdle detached from skull
4. Pelvic girdle fused to sacral vertebrae

Question 8

Advantages of terrestrial tetrapods having forward-pointing digits

Answer 8

Increased tractive (pulling) and propulsive (pushing) forces

Question 9

Components of terrestrial limb locomotion during walking/running

Answer 9

Propulsion: contact ground, push/pull body forwards
Recovery: don’t contact ground, bring limb back to propulsive position

Question 10

Pectoral girdle composition in teleostomi

Answer 10

Dermal & replacement bone

Question 11

Which pelvic girdle bone in tetrapods fuses to the sacral vertebrae?

Answer 11

Ilium

Question 12

Use of sarcopterygiian fins

Answer 12

Highly maneuverable -> propulsion, pivoting, supporting some weight

Question 13

2 types of terrestrial tetrapod limb posture

Answer 13

Sprawled (to sides) - many amphibians & sauropsids

Erect (limbs beneath body)

Question 14

What is included in the appendicular skeleton?

Answer 14

Paired appendages & supporting girdles

Question 15

Describe pelvic girdle of birds & reasoning

Answer 15

3 bones fuse into innominate bone; provides stability in flight & strength to withstand forces of landing

Question 16

Pectoral girdle attachment in chondrichthyes

Answer 16

Suspended in body wall muscle

Question 17

Advantages of erect limb posture

Answer 17

Recovery stroke is efficient pendulum-swing (cursorial movement) -> sagittal plane movement only

Question 18

Describe fin support in jawed fish

Answer 18

Proximal: Sturdy elements
Distal: Fin rays

Question 19

Bones of pelvic girdle in tetrapods

Answer 19

Ilium, ischium, pubis

Question 20

Pelvic girdle composition in teleostomi

Answer 20

Replacement bone

Question 21

Why would tetrapods have sturdier, more ossified girdles than sarcopterygiians?

Answer 21

Better to support weight and locomotion

Question 22

Effect of erect limb posture on girdles

Answer 22

Forces directed upwards, so strong dorsal pectoral girdle (scapula) vs small ventral girdle (clavicles)

Question 23

Advantages of sprawled limb posture

Answer 23

Retain lateral undulation -> good for swimming

Question 24

Function of paired fins in sharks & why

Answer 24

Provide stability (against pitch, roll, yaw) b/c stiff & inflexible
Adjust angle for steering

Question 25

Advantages of thick digits of tetrapods over sarcopterygiian thin fin rays

Answer 25

better grip, better weight support, sturdier

Question 26

Describe pectoral girdle attachment in tetrapods & reasoning

Answer 26

Axial skeleton suspended like a sling by muscles; acts as shock absorber so landing/impact doesn't transmit forces to skull & brain

Question 27

Why are distal regions of jawed fish fins supported by fin rays?

Answer 27

Allow control over surface area of fin hitting water

Question 28

Benefits of detaching pectoral girdle from cranium in sarcopterygii -> tetrapods

Answer 28

Head moves independently Pectoral girdle at better angle (digits can point forwards instead of splaying outwards) Brain not jarred on each step

Question 29

Disadvantages of sprawled limb posture

Answer 29

Recovery stroke requires slow, expensive over-arm swing (dorsal/ventral movement as well as anterior/posterior)

Question 30

What's special about male sharks' pelvic girdles?

Answer 30

Have long claspers to transfer sperm for internal fertilization

Question 31

Function of pelvic & pectoral girdles

Answer 31

Brace, support paired appendages & provide attachment sites for the muscles controlling them

Question 32

Describe pectoral girdle structure in tetrapods compared to osteichthyans

Answer 32

Smaller dermal bone components (clavicles) | Larger replacment bones (scapulas, procoracoid, coracoid)

Question 33

Function of actinopterygiian fins & why they can do this

Answer 33

Steer, balance, propel | -flexible & mobile -> can execute precise maneuvers, but doesn't provide speed

Question 34

Pectoral girdle attachment in osteichthyes

Answer 34

Fused to vertebral column & sometimes also to skull

Question 35

Benefits of fusing pelvic girdle to sacral vertebrae in tetrapods

Answer 35

More efficient transfer of energy from hindlimb propulsion to vertebral column via girdle

Question 36

Describe adaptation of pectoral girdle in birds

Answer 36

Clavicles fuse into furculum; acts as spring to make flight & breathing more efficient