Biomechanical modeling and sensitivity analysis of bipedal running ability. II. Extinct taxa

摘要: I used a simple mathematical model of the inverse dynamics locomotion to estimate minimum muscle masses required maintain quasi-static equilibrium about four main limb joints at mid-stance fast running. Models 10 extant taxa (a human, kangaroo, two lizards, an alligator, and five birds) were analyzed in various bipedal poses examine how anatomy, size, orientation, other parameters influence running ability. examined for compare that are actually able exert moments hip, knee, ankle, toe joints, see support ability varies across limb. discuss assumptions limitations models, using sensitivity analysis widely results differed with feasible parameter input values. Even wide range values, models validated procedure. Animals known run bipedally calculated as preserve their hindlimb mid-stance, whereas non-bipedal runners (iguanas alligators) recognized having too little mass quickly poses. Thus, this modeling approach should be reliable reconstructing extinct bipeds such nonavian dinosaurs. The also elucidated key features important capacity, moment arms, fascicle lengths, body size. None animals modeled had extensor acting any one joint 7% or more mass, which provides reasonable limit much is normally apportioned within act particular joint. consistently showed biomechanical on capacity ankle extensors generate sufficiently large moments. Additionally, reveals ratite birds remain excellent despite larger size; they have apomorphically muscles relatively high effective mechanical advantage. Finally, reconstructed evolution clade Reptilia, showing ancestors likely quite capable runners, even though already reduced hip M. caudofemoralis longus.