Figure 2. General kinematic characteristics.

Range of angular motion (ROM) of limb segment elevation angles (see schematic drawing on the right) averaged across strides for each animal. Different markers and colors refer to different taxonomic orders. Empty and filled markers refer to FL and HL values, respectively. Source files are available in the SourceData2-Figure2.zip file.

Figure 2—figure supplement 1. Anatomical landmarks and segments used for the kinematic model of bipedal.

(A) and quadrupedal (B) locomotion superimposed on a bird and mammal skeleton (left panels) and extracted video frames (right panels) of the recorded animals. For the kinematic data digitized from Fischer et al. (2002) (animals marked by asterisks in Table 1), the same definition of elevation angles was used.

Figure 2—figure supplement 2. General gait parameters.

(A) Schematic drawing of a walking dog with stick diagram indicating the distal points analyzed and limb contact pattern on the bottom. HL, FL refer to hindlimb and forelimb facing the recording camera, while HL_contr, FL_contr indicate the contralateral ones. Grey bars indicate the period of time in which each foot is in contact with the ground during the stride. (B) Mean FL phase lag (t_FL) values plotted versus contralateral FL values (t_FLcontr) for all animals. The phase lag was computed as the relative timing (t_FL, t_FLcontr) of the FL cycle onset with respect to HL, expressed as a percentage of the gait cycle (see panel A). (C) Relative duration of the stance phase (mean +SD across animals). Asterisk indicates significant differences between HL and FL of mammals (p<0.001). (D) Stride duration. (E) Mean trunk inclination during walking with respect to the horizon. (F) Endpoint motion. The stick diagram of a single stride of a walking dog illustrates limb segment movements relative to hip (for HL) and scapula (for FL). Bottom plots show vertical vs. horizontal limb endpoint excursions, normalized to the limb length (L equals to the sum of the lengths of thigh, shank, and foot segments). The data in panels B-F do not include animals marked by asterisks in Table 1 (since this information is missing in Fischer et al., 2002). Animals are labeled as in Table 1 and different colors and markers refer to different taxonomic orders and species, respectively. Source files are available in the SourceData2-Figure 2—figure supplement 2—souce data 1.zip file.