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Figure 27 in Three-dimensional geometry of a pterosaur wing skeleton, and its implications for aerial and terrestrial locomotion

Figure 27. Dorsal (A), anterior (B), and left lateral (C) views of Anhanguera in a semi-erect quadrupedal stance. The shoulder and intersyncarpal joints are in their close-packed positions, the carpometacarpal joints are supinated, and the elbow, radioulnocarpal, knuckle, and carpopteroid joints are maximally flexed. The femora are depressed by 60°. Scale bar: 500 mm.

Figure 9. A in Three-dimensional geometry of a pterosaur wing skeleton, and its implications for aerial and terrestrial locomotion

Figure 9. A, reconstructed articular surfaces of the right radioulnocarpal joint of Coloborhynchus robustus. Elements are oriented as in Fig. 7: radius and ulna in lateral view, and proximal syncarpal in medial view. Scale bar: 50 mm. B, diagrammatic representation of (A), showing contact areas in the close-packed position, the joint axis, and the conjunct rotation axis. C, right radius, ulna, syncarpals, and wing metacarpal in their respective close-packed positions in posterodorsal aspect, viewed along the radioulnocarpal joint axis. For a list of anatomical/arthrological abbreviations, see Appendix 1.

Figure 23 in Three-dimensional geometry of a pterosaur wing skeleton, and its implications for aerial and terrestrial locomotion

Figure 23. Methods of changing the angle of attack of the inner wing. A, left lateral view of Anhanguera configured as in Fig. 18. The broken line indicates the chord line. The angle of attack of the section is zero. B, as in (A), but with the left leg depressed at the hip by 30°. The geometric angle of attack a is indicated. C, as in (A), but with the leg supinated at the hip by 30°. The leg movements shown in (B) and (C) increase both the angle of attack and the camber of the inner wing.

Figure 24 in Three-dimensional geometry of a pterosaur wing skeleton, and its implications for aerial and terrestrial locomotion

Figure 24. Effects of pteroid depression. A, left lateral view of Anhanguera as in Fig. 23. B, as in (A), but with the left pteroid depressed by 30°. The camber is increased and the angle of attack, a, is reduced by this movement.

Figure 21. A in Three-dimensional geometry of a pterosaur wing skeleton, and its implications for aerial and terrestrial locomotion

Figure 21. A, typical plots of pitching moment M against angle of attack a (measured with respect to the zero-lift angle of attack) for stable and unstable aircraft. Both aircraft are shown balancing at the same equilibrium angle of attack, at which point the pitching moment is zero. B, the effect of raising the elevators (1) on the longitudinal balance of a stable aircraft: the pitching moment is increased, as is the equilibrium angle of attack, so the aircraft pitches up (2) until equilibrium is restored. C, the effect of raising the elevators (1) on the longitudinal balance of an unstable aircraft: the pitching moment is increased, but the equilibrium angle of attack is reduced, so the aircraft now pitches up away from equilibrium (2).

Figure 15. A in Three-dimensional geometry of a pterosaur wing skeleton, and its implications for aerial and terrestrial locomotion

Figure 15. A, reconstructed articular surfaces of the right carpometacarpal joint of Coloborhynchus robustus. Elements are oriented as in Fig. 7: distal syncarpal in lateral view and wing metacarpal in medial view. Scale bar: 50 mm. B, diagrammatic representation of (A), showing contact areas in the close-packed position and the joint axis. For a list of anatomical/arthrological abbreviations, see Appendix 1.

Figure 22 in Three-dimensional geometry of a pterosaur wing skeleton, and its implications for aerial and terrestrial locomotion

Figure 22. Increasing the equilibrium angle of attack of an unstable aircraft can be brought about by decreasing the derivative dM/da, where M is the pitching moment and a is the angle of attack, by sweeping the wings back (A), or by decreasing the zero-lift pitching moment M0, by depressing the pteroids for example (B). These adjustments can theoretically be used in response to an unstable nose-up pitch (1), thus establishing a new equilibrium (2).

Figure 19. A in Three-dimensional geometry of a pterosaur wing skeleton, and its implications for aerial and terrestrial locomotion

Figure 19. A, Stable but unbalanced wing profile, with the centre of gravity (c.g.) situated ahead of the mean aerodynamic centre (m.a.c.). B, stable and balanced configuration, with a small tailplane set at a negative incidence with respect to the main wing.

Figure 1 in The effects of locomotion on the structural characteristics of avian limb bones

Figure 1. Avian phylogenies used for tests of phylogenetic independence. A, the phylogeny based on the topology presented by Sibley & Ahlquist (1990). B, the phylogeny based on the topology presented by Livezey & Zusi (2007).

Figure 2 in The effects of locomotion on the structural characteristics of avian limb bones

Figure 2. Polar section moduli of femora versus section moduli of humeri for all individuals, standardized for bone length (see text). Zp is used here as an estimate of strength in torsion and average strength in bending. The solid line represents equal strength (y = x). Data are presented natural log transformed, and symbols correspond to locomotor categories in Table 1. De, Diomedea exulans; Ac, Aquila chrysaetos; Sm, Spheniscus magellanicus; Ph, Phalacrocorax harrisi; Pa, P. auritus; Ao, Aechmophorus occidentalis; Pg, Puffinus griseus; Ua, Uria aalge; Cc, Corvus corax; Cm, Cerorhinca monocerata; Ta, Tyto alba; Ft, Falco tinnunculus; Gc, Geococcyx californianus; Pr, Phaethon rubricauda; Ra, Rhea americana. The single juvenile rhea was not used in statistical analyses. The long axis of ovals delimiting species indicate isometry. Symbols are as follows, filled symbols, diving birds (those with subaqueous locomotion); triangles (Δ), forelimb-propelled diving; squares (-,Z), flightless taxa. Grebes are indicated by diamonds (Ɨ) and volant cormorants are shown with filled circles (•). The single juvenile rhea is indicated by a cross (+). All other species are delimited by open circles (O).

Figure 7 in The effects of locomotion on the structural characteristics of avian limb bones

Figure 7. Percentage of bone cross-section composed of cortical bone in the femur and humerus of each individual. This represents an inverse measure of 'hollowness' in the limb bones scanned. Phalacrocorax harrisi and Spheniscus magellanicus are both highlighted for qualitative reference, as these species have the thickest-walled bones of the taxa studied. Phalacrocorax auritus individuals are highlighted for comparison with P. harrisi. Puffinus griseus individuals, which utilize both dynamic soaring and wing-propelled diving, are highlighted to emphasize that their cortical areas are similar to other divers. Symbols and labels are as in Figure 2, except that X's denote hyperaerials.

Figure 4. pQCT images from a in The effects of locomotion on the structural characteristics of avian limb bones

Figure 4. pQCT images from a subset of the study species included, representing the range of geometries in the data set. Species not shown to same scale.

Figure 6 in The effects of locomotion on the structural characteristics of avian limb bones

Figure 6. Mean natural log-transformed ratios of femoral to humeral length. Taxa are ordered according to the expected functional trend (see Table 1).

Figure 3 in The effects of locomotion on the structural characteristics of avian limb bones

Figure 3. Mean natural log-ransformed ratios of femoral to humeral section modulus. Taxa are ordered according to the expected functional trend (see Table 1).

Figure 5 in The effects of locomotion on the structural characteristics of avian limb bones

Figure 5. Total length of femora versus total length of humeri for all individuals. Data are presented natural log-transformed. The solid line represents equal length (y = x). Symbols and species name abbreviations follow those in Figure 2. The long axes of the ovals delimiting species indicate isometry.

opencc-by-4.0Aug 2022View details →

Supplementary Videos for "Underwater-sailing locomotion in intertidal gastropods: a comparison of Neotropical species"

The six videos available below accompany my article, "Underwater-sailing locomotion in intertidal gastropods: a comparison of neotropical species", published in Archiv für Molluskenkunde 151: 93-105 (2022), https://doi.org/10.1127/arch.moll/151/093-105.   Supplementary Video 1. Bullia digitalis        0′04′′–0′18′′   Underwater-sailing locomotion                        0′14′′  Cruising animal switches direction of movement                        0′16′′  Two cruising animals pass each other while moving in opposite directions        0′19′′–0′37′′   Full-sail response in shaking-tray test; foot rotation   Supplementary Video 2. Agaronia propatula        0′04′′–0′28′′   Underwater-sailing locomotion        0′29′′–0′59′′   Underwater-sailing locomotion with prey in metapodial pouch        1′00′′–1′12′′   Full-sail response triggered by minor vibration        1′13′′–1′26′′   Full-sail response triggered by flush of water   Supplementary Video 3. Pachyoliva semistriata, P. columellaris        0′04′′–0′27′′   Underwater-sailing locomotion (P. semistriata)        0′28′′–0′52′′   Full-sail response triggered by shaking (P. columellaris)        0′53′′–1′04′′   Full-sail response triggered by falling (P. columellaris)   Supplementary Video 4. Hastula cinerea, H. salleana        0′04′′–0′23′′   Underwater-sailing locomotion (H. cinerea)        0′24′′–0′52′′   Full-sail response triggered by current (H. salleana)        0′53′′–1′24′′   Full-sail response triggered by shaking (H. salleana)   Supplementary Video 5. Mazatlania fulgurata        0′04′′–0′22′′   Apparent full-sail response triggered by shaking; foot rotation        0′23′′–0′43′′   Apparent full-sail response triggered by shaking in deep sand; foot rotation   Supplementary Video 6. Animals with expanded foot glide down a water column        0′07′′–0′33′′   Agaronia propatula        0′34′′–0′56′′   Pachyoliva semistriata        0′57′′–1′13′′   Hastula cinerea        1′14′′–1′30′′   Mazatlania fulgurata

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Data from: Behavior shapes retinal motion statistics during natural locomotion

Walking through an environment generates retinal motion, which humans rely on to perform a variety of visual tasks. Retinal motion patterns are determined by an interconnected set of factors, including gaze location, gaze stabilization, the structure of the environment, and the walker's goals. The characteristics of these motion signals have important consequences for neural organization and behavior. However, to date, there are no empirical in situ measurements of how combined eye and body movements interact with real 3D environments to shape the statistics of retinal motion signals. Here, we collect measurements of the eyes, the body, and the 3D environment during locomotion. We describe properties of the resulting retinal motion patterns. We explain how these patterns are shaped by gaze location in the world, as well as by behavior, and how they may provide a template for the way motion sensitivity and receptive field properties vary across the visual field.

opencc-zeroApr 2023View details →

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Data for: Mobility of the human foot's medial arch helps enables upright bipedal locomotion

Developing the ability to habitually walk and run upright on two feet is one of the most significant transformations to have occurred in human evolution. Many musculoskeletal adaptations enabled bipedal locomotion, including dramatic structural changes to the foot and, in particular, the evolution of an elevated medial arch. The foot's arched structure has previously been assumed to play a central role in directly propelling the center of mass forward and upward through leverage about the toes and a spring-like energy recoil. However, it is unclear whether or how the plantarflexion mobility and height of the medial arch support its propulsive lever function. Here we show, using high-speed biplanar x-ray, that regardless of intraspecific differences in medial arch height, arch recoil enables a longer contact time and favorable propulsive conditions at the ankle for walking upright on an extended leg. This mechanism may have helped drive the evolution of the longitudinal arch after our last common ancestor with chimpanzees, who lack this plantarflexion mobility during push-off. We discovered that the generally overlooked navicular-medial cuneiform joint is primarily responsible for arch recoil in human arches, suggesting that future morphological investigations of this joint will provide new interpretations of the fossil record. Our work further suggests that enabling longitudinal arch recoil in footwear and surgical interventions may be critical for maintaining the ankle's natural propulsive ability.

opencc-zeroApr 2023View details →

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Mantis shrimp locomotion: coordination and variation of hybrid metachronal swimming

Across countless marine invertebrates, coordination of closely spaced swimming appendages is key to producing diverse locomotory behaviors. Using a widespread mechanism termed hybrid metachronal propulsion, mantis shrimp swim by moving five paddle-like pleopods along their abdomen in a posterior to anterior sequence during the power stroke and a near-synchronous motion during the recovery stroke. Despite the ubiquity of this mechanism, it is not clear how hybrid metachronal swimmers coordinate and modify individual appendage movements to achieve a range of swimming capabilities. Using high-speed imaging, we measured pleopod kinematics of mantis shrimp (Neogonodactylus bredini) while they performed two swimming behaviors: burst swimming and taking off from the substrate. By tracking each of the five pleopods, we tested how stroke kinematics vary across swimming speeds and the two swimming behaviors. We found that mantis shrimp achieve faster swimming speeds through a combination of higher beat frequencies, smaller stroke durations, and partially via larger stroke angles. The five pleopods exhibit non-uniform kinematics that contribute to the coordination and forward propulsion of the whole system. Micro-hook structures (retinacula) connect each of the five pleopod pairs and differ in their attachment across pleopods – possibly contributing to passive kinematic control. We compare our findings in N. bredini to previous studies to identify commonalities across hybrid metachronal swimmers at high Reynolds numbers and centimeter scales. Through our large experimental dataset and by tracking each pleopod's movements, our study reveals key parameters by which mantis shrimp adjust and control their swimming, yielding diverse locomotor abilities.

opencc-zeroMay 2023View details →