Size Matters

Question 1

Alexander, Jayes, Maloiy and Wathuta - April 1979

HYPOTHESIS

Answer 1

• If mammals of different sizes are geometrically similar, the lengths/diameters of corresponding limbs are proportional to body mass^0.33
• Mcmahons theory predicts length ∝ BM^0.25 and diameter ∝ BM^0.38

Question 2

Alexander, Jayes, Maloiy and Wathuta - April 1979

RESULTS

Answer 2

• Length ∝ BM^0.35

- Diameter ∝ BM^0.36

Question 3

Alexander, Jayes, Maloiy and Wathuta - April 1979

METHOD

Answer 3

• 435 different measurements obtained
• Measurements from bones on 1 side of the body
• Steel rule and vernier caliper used

Least squares regression used to obtain allometric Eq

Question 4

A.A.Biewener - January 1982

HYPOTHESIS

Answer 4

Bone strength varies with animal size

Question 5

A.A.Biewener - January 1982

Results

Answer 5

• No significant strength difference found in bones of various size therefore large animals have less SF
• Small animal bones far stronger than necessary or other aspects of locomotion act to decrease peak locomotory stresses

Question 6

A.A.Biewener - January 1982

METHOD

Answer 6

Fracture strength of principle ones tested in 3-point bending and compared with published data

Question 7

A.A.Biewener - July 1989

HYPOTHESIS

Answer 7

• Theorised that peak bone stress in mammals from 0.1kg-300kg is independent of bone size and a SF of 2-4 is maintained
• These stress changes achieved by a size dependent change in limb posture (crouched for mammals, upright for larger species)

Question 8

A.A.Biewener - July 1989

RESULTS

Answer 8

• Mechanical advantage increased with body mass (forelimb and hindlimb)
• Overall scaling ∝ BM^0.258
• Newtons/kg decreases with size through EMA

Question 9

A.A.Biewener - July 1989

METHOD

Answer 9

• Different sized mammals made to run over force platform

- Filmed with lateral view to determine EMA

Question 10

S.R.Bullimore and J.F.Burn - December 2003

HYPOTHESIS

Answer 10

• For animals to move in a dynamically similar way, they must exhibit distortions of limb structure to compensate for size independence of tendon elastic-modulus
• Tendon EM has significant effect on dynamics of locomotion due to effect on limb stiffness

Question 11

S.R.Bullimore and J.F.Burn - December 2003

RESULTS

Answer 11

Mammals show some dynamic similarity at equal Froude No, but other parameters will systematically deviate from dynamic similarity

Question 12

Garland - June 1982

HYPOTHESIS

Answer 12

Determine empirical relationship between max running speed and body mass

Question 13

Garland - June 1982

RESULTS

Answer 13

• MRS scales as BM^0.17
• Agrees with predictions of dynamically similar animals
• Optimal speed with regards to running approx 119kg

Question 14

Garland - June 1982

METHOD

Answer 14

Comparison of available data on speed of mammals

Question 15

C.M.Pollock and R.E.Shadwick - August 1993

HYPOTHESIS

Answer 15

Investigated allometric relationships between mechanical properties of various limb tendons and body mass

Question 16

C.M.Pollock and R.E.Shadwick - August 1993

RESULTS

Answer 16

Elastic modulus and hysteresis of digital flexor, ankle extensor and digital extensor tendons do not vary significantly between animals of different body mass

Question 17

C.M.Pollock and R.E.Shadwick - August 1993

METHOD

Answer 17

The elastic modulus and hysteresis of digital flexor, ankle extensor and digital extensor tendons from 18 species of quadrupedal mammals from 0.5kg to 545kg were determined from cyclic tensile testing in vitro.