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 running
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 Horse 42 540 cursorial Lion 50 180 Cheetah 63 35 (independent trend Dinosaurs) Pronghorn 59 90 Human 22 85 Coyote 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
8