Chapter 9 part 3: Appendicular Skeleton

Question 1

Tibiofibular

Answer 1

Tibia (Shinbone): The larger and stronger of the two bones. It bears most of the body’s weight and forms the major part of both the knee joint (at the top) and the ankle joint (at the bottom). It’s critical for weight-bearing and movement.

Fibula: The smaller and thinner bone located alongside the tibia. While it doesn’t bear much weight, it provides stability to the leg. The fibula helps form the ankle joint and provides points for muscle attachment.

Relationship: These bones are connected by a membrane called the interosseous membrane. This membrane helps stabilize the bones and allows for some movement.

Question 2

Tibiotarsus

Answer 2

The tibiotarsus is a bone primarily found in birds. It’s fusion of two bones—the tibia and the proximal tarsal bones—forming a single, elongated structure. This bone is crucial for birds’ locomotion, supporting their unique walking, running, and perching needs.

Tibia: Originally part of the lower leg in vertebrates.
Tarsus: Consists of the ankle bones.
optimizing their skeletal structure for efficient movement.

Question 3

Tarsometatarsus

Answer 3

The tarsometatarsus is a fusion bone found primarily in birds. This bone results from the fusion of the distal tarsal bones (the ankle bones) with the metatarsals (the long bones of the foot) during development.

Function: The tarsometatarsus plays a crucial role in supporting the bird’s body during walking, running, and perching.

Question 4

What are two modifications to the orientation of the limbs in mammals?

Answer 4

Reorientation of the limbs: transition from suspended limbs to body on top of limbs

Rotation from sideways limps to limbs facing in cranial direction, very early tetrapod orientation
 Foot orientation

Question 5

Name the types of mammalian limbs

Answer 5

Unguligrade
Digitigrade
Plantigrade

Question 6

Unguligrade

Answer 6

Ungulates/Unguligrade: walking aorund on tippy toes, hooved; 2 types

Perissodactyla: odd toed, axis of foot through 3rd digit
Artilodactyla: even-toed, axis through 3rd and 4th digit

Question 7

Digitigrade

Answer 7

PWeight of borne on 4th digits, retractable claws in some feliforms(cats!)

Question 8

Plantigrade

Answer 8

Phalanges flat; Tarsals, metatarsals, and digits flat on substrate
Example: humans, bears

Question 9

Aquatic

Answer 9

animals swim

Question 10

Volant

Answer 10

animals fly

Question 11

What is cursorial locomotion?

Answer 11

Cursorial animals (cursors) run rapidly and for long distances

Include stride length and stride rate

Question 12

Scansorial

Answer 12

animals that are climbers; in the extreme, they are arboreal, spending most of their lives in the trees

Question 13

Saltatorial

Answer 13

hopper animals

Question 14

Ricochetal

Answer 14

If they use their hindlimbs only and in a fast succession of hops

Example: Kangaroos
 Very long fourth digit, especially the metatarsal
 The fifth digit is also important, but smaller than the fourth
 Tendons in posterior limb store elastic energy, release it to push foot down

Question 15

Fossoiral

Answer 15

digger animals, usually live in burrows

Question 16

Describe Stride Length and the adaptations for increasing it

Answer 16

 Run on the tips of the toes
 Lengthen limb elements
 Flexing the spine

Question 17

Describe adaptations for increasing stride rate

Answer 17

 Muscles inserted close to joints make the bones on which they insert move faster
 Decrease mass of distal limb(end of limb)

Question 18

Describe cheetah example of stride

Answer 18

short bursts – flexion of axial skeleton to increase stride length, periods of suspension
* Comrpess and extend axial skeleton

Question 19

Describe example of stride in ungulates

Answer 19

(horse, deer): sustained locomotion - vertebral column flexes much less to avoid the exhausting vertical rise and fall of the body mass characteristic of the cheetah

A less flexible vertebral column keeps the mass of the horse more linear along its line of travel

The lead foot and trailing foot change during sustained bouts of rapid running

Question 20

Describe visual of stride rate

Answer 20

Ancestral mammal when increasing length(elongation of metapodials), we get the cheetah, deer, and horse(mammals)

Limb muscles positioned toward the body – decreases weight of distal limb

Primitive amniote when having reduction in number of elements, led to archosuars(saurischians)

Question 21

What is the difference between gliding and powered flight?

Answer 21

Gliding has free fall resisitance dpending on the weight and direction of motion for a species; Relies on gravity and air currents

Powered flight has the ability to lift the species using energy and muscles specifically made for flight; Relies on constant flapping and energy usage; Counteracts drag and gravity with lift and thrust

Question 22

What are the 2 major flight muscles in birds?

Answer 22

Pectoralis: pulls wing down
Supracoracoideus: raises wing

Note that differences in wing shape allow for different types of flight
Soaring in raptors; Opening of primaries in flight seen for hawks; Smaller sizes seen for speed; Thicker, shorter wings seen in enclosed habitats

Question 23

What is the Bernoulli effect?

Answer 23

Pressure differential that generates lift; Can glide well without even flapping; Air moving faster over the top of the wing and slower under the wing

Airfoil shape; convex top and concave bottom, creates net lift force to glide; Birds can use updrafts, ridge soaring, and thermals(heat rising and bird riding that vortex) to glide; using environment