The Suspension System Fish water Î land

Static—fixed, gravity Dynamic—motion tail Î limbs/girdles

Tetrapods

The Suspension System Early modes of locomotion water Î land

• Lateral undulations Static—fixed, gravity • Mode of modern amphibians and Dynamic—motion reptiles. tail Î limbs/girdles On land specialized modes

Differentiation Vertebral Column Modes of Locomotion

• Fossorial - digging • Arboreal – climbing (grip) • Scansorial – climbing (claws) • Saltatorial - jumping • Aerial –flying • Cursorial – rapid

1 Cursorial Locomotion Cursorial Locomotion and Biological Role Amphibians and present day Reptiles Maximum Speeds and Sizes of lateral undulations of vertebral Cursorial Animals column Animal Maximum Speed Weight (mph) (kg)

Mammals Fox 37 4.5 42 540 cursorial Lion 50 180 63 35 (independent trend Dinosaurs) Pronghorn 59 90 Human 22 85 42 10

Cursorial Locomotion why evolve? Dispersed Resources

Catch Escape

Therapsids

2 Early modes of locomotion

• Lateral-sequence gait: three of the four limbs are in contact with the ground at the same time. –More stable

Early modes of locomotion Early modes of locomotion

•Gait: pattern of foot contacts with the substrate

• Lateral-sequence gait: three of the four limbs are in contact with the ground at the same time.

Lizard --bipedal Cursorial Locomotion: Running Fast, Running Long

3 Limbs Under Body ADAPTATIONS Cursorial Locomotion: Running Fast Limbs under the body Speed = Stride Length x Stride Rate

Stride Length Stride Length

•Lengthen limb •Lengthen limb – Distal elements – Distal elements lengthen – Change in foot posture

Stride Length Cursorial Locomotion

•Lengthen limb • Increase the distance – Distal elements through which the – Change in foot limbs move while posture they are off the ground – Add another joint to locomotor mechanism • Flexion of the vertebral column

Hildebrand

4 Stride Length Increase the distance through which the limbs move while they are off the ground Speed = Stride Length x Stride Rate

Flexion of the vertebral column

Stride Rate Stride rate Massing of muscles close NOT reduce muscle 1) muscle to body 2) mass limb 3) shorten limb Lighten limb (distally). Reduce moment of inertia

Stride Rate Stride Rate summary • Flexion of the limb during recovery Digits effectively shortens it, reduced increasing the rate of oscillation.

Lighten limb (distally). • Lighten the distal end of Reduce moment of inertia the limb. --muscle mass --Reduction in digits

5 GAITS Gaits: The Amble footfall: pattern of foot touches • Fore- and hindfeet on the same side more or less in unison. • Functional Significance • Long-legged animals • Why change gaits? •A fast amble is called Hildebrand a pace.

Gaits: The Trot Half bound and Gallop • Fast speeds. • Moves diagonally • Halfbound: hindfeet contact opposite feet at same time, forefeet display a together. distinct leading and trailing pattern. • Connecting line of • Gallop: both fore- and hindfeet support runs directly display a distinct leading and under the center of trailing pattern. mass. • Asymmetric gaits • Suspension phase

XXX X 6 Gallop 8 Trot

Gaits: The Bound (Pronk)

• All four feet strike the ground in unison. • Decelerates the animal • Allows them to clear low brush? •Advertise? Hildebrand

6 Cursorial Locomotion and Biological Role • Gait and mass

Hildebrand

Cursorial Locomotion and Biological Role

Walk Trot Gallop Metabolic Cost—Oxygen / / meter Cost—Oxygen Metabolic

Speed m/s Æ 1 2 3 4 5 6 7 8 9

Horse Cheetah Saltatorial Physics: large small Biology: endurance speed

7 Saltatorial Comparative Anatomy Changes in vertebrate body with the passage of time

SIGNIFICANCE OF THOSE CHANGES

a) Functional Significance Biomechanics Water Î Land Cursorial

Comparative Anatomy Changes in vertebrate body with the passage of time

SIGNIFICANCE OF THOSE CHANGES

b) Evolutionary significance Remodel Preadaptation

Relax Î

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