Joint-level coordination patterns for split-belt walking across different speed ratios.

Locomotion is a highly flexible process, requiring rapid changes to gait due to changes in the environment or goals. Here, we used a split-belt treadmill to examine how the central nervous system coordinates a novel gait pattern. Existing research has focused on summary measures, most often step lengths, when describing changes induced while walking on the split-belt treadmill and during subsequent aftereffects.

A proposed standard for quantifying 3-D hindlimb joint poses in living and extinct archosaurs.

The last common ancestor of birds and crocodylians plus all of its descendants (clade Archosauria) dominated terrestrial Mesozoic ecosystems, giving rise to disparate body plans, sizes, and modes of locomotion. As in the fields of vertebrate morphology and paleontology more generally, studies of archosaur skeletal structure have come to depend on tools for acquiring, measuring, and exploring three-dimensional (3-D) digital models. Such models, in turn, form the basis for many analyses of musculoskeletal function.

A new role for joint mobility in reconstructing vertebrate locomotor evolution.

Reconstructions of movement in extinct animals are critical to our understanding of major transformations in vertebrate locomotor evolution. Estimates of joint range of motion (ROM) have long been used to exclude anatomically impossible joint poses from hypothesized gait cycles. Here we demonstrate how comparative ROM data can be harnessed in a different way to better constrain locomotor reconstructions.

Gearing effects of the patella (knee extensor muscle sesamoid) of the helmeted guineafowl during terrestrial locomotion.

Human patellae (kneecaps) are thought to act as gears, altering the mechanical advantage of knee extensor muscles during running. Similar sesamoids have evolved in the knee extensor tendon independently in birds, but it is unknown if these also affect the mechanical advantage of knee extensors. Here, we examine the mechanics of the patellofemoral joint in the helmeted guineafowl using a method based on muscle and tendon moment arms taken about the patella's rotation centre around the distal femur.

3-D range of motion envelopes reveal interacting degrees of freedom in avian hind limb joints.

Measuring range of motion (ROM) is a valuable technique that can link bone morphology to joint function in both extant and extinct taxa. ROM results are commonly presented as tables or graphs of maxima and minima for each rotational degree of freedom. We investigate the interactions among three degrees of freedom using X-ray reconstruction of moving morphology (XROMM) to measure ROM of the main hind limb joints of Helmeted Guineafowl (Numida meleagris).