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Estimates of speeds of dinosaurs
- R. Alexander
- Environmental ScienceNature
- 1 May 1976
THE faster an animal walks or runs the longer, in general, are its strides. Many dinosaur tracks have been found from which stride lengths can be measured1 .I have now obtained a relationship between…
A dynamic similarity hypothesis for the gaits of quadrupedal mammals
The dynamic similarity hypothesis postulates that different mammals move in a dynamically similar fashion whenever they travel at speeds that give them equal values of a dimensionless parameter, the Froude number, and is found to be tenable in many cases when comparisons are confined to quadrupedal mammals.
Why are mammalian tendons so thick
The maximum stresses to which a wide range of mammalian limb tendons could be subjected in life were estimated by considering the relative cross‐sectional areas of each tendon and of the fibres of its muscle, and a new theory explains the thickness of the majority of tendons.
The spring in the arch of the human foot
It is shown that the elastic properties of the arch of the human foot are also important, which means that the animal runs in an analogous fashion to a rubber ball bouncing along.
Mechanical properties of various mammalian tendons
Dynamic tensile tests have been performed on various tendons from the legs and tails of 10 species of mammal, finding little or no dependence of modulus or energy dissipation on frequency, in the range 0·2–11 Hz.
Allometry of the leg muscles of mammals
Differences between primates; fissipedes, bovids and bipedal hoppers are demonstrated and departures from geometric similarity in mammals in general are noted and discussed.
The Gaits of Bipedal and Quadrupedal Animals
- R. Alexander
- 1 June 1984
The gaits of turtles appear to reduce unwanted displacements (pitch, roll, etc.) to the minimum possible for animals with such slow muscles, and much of the energy that would otherwise be needed for running by people and other large mammals is saved by tendon elasticity.
Storage of elastic strain energy in muscle and other tissues
The elastic materials involved include muscle in every case, but only in insect flight is the proportion of the energy stored in the muscle substantial.
The thickness of the walls of tubular bones
A theoretical analysis shows that the optimum value of K, which allows the mass of a bone to be minimized, depends on whether the bone is selected principally for yield or fatigue strength, for ultimate strength,For impact strength or for stiffness.
A theory of metabolic costs for bipedal gaits.
A simple model predicts the energy cost of bipedal locomotion for given speed, stride length, duty factor and shape factor, and predicts lower duty factors and higher shape factors than are normally used, but the relationships between these gait parameters and speed parallel the empirical relationships.