Inverse dynamic modelling of jumping in the red-legged running frogKassina maculata

Abstract

Although the red-legged running frog, Kassina maculata, is secondarily a walker/runner, it retains the capacity for multiple locomotor modes, including jumping at a wide range of angles (nearly 70 deg). Using simultaneous hind limb kinematics and singlefoot ground reaction forces, we performed inverse dynamics analyses to calculate moment arms and torques about the hind limb joints during jumping at different angles in K. maculata. We show that forward thrust is generated primarily at the hip and ankle, while body elevation is primarily driven by the ankle. Steeper jumps are achieved by increased thrust at the hip and ankle and greater downward rotation of the distal limb segments. Because of its proximity to the GRF vector, knee posture appears to be important in controlling torque directions about this joint and, potentially, torque magnitudes at more distal joints. Other factors correlated with higher jump angles include increased body angle in the preparatory phase, faster joint openings and increased joint excursion, higher ventrally directed force, and greater acceleration and velocity. Finally, we demonstrate that jumping performance in K. maculata does not appear to be compromised by presumed adaptation to walking/ running. Our results provide new insights into how frogs engage in a wide range of locomotor behaviours and the multi-functionality of anuran limbs.

Digital dissection of the model organism Xenopus laevis using contrast‐enhanced computed tomography

“…; Porro et al. ); this contrasts with the more basally positioned and almost exclusively aquatic X. laevis . Scan data from K. maculata were included to compare the unusual osteology of X. laevis with that of a taxon possessing a skeletal morphology and locomotor modes more typical of anurans.…”

“…An unstained specimen of Kassina maculata (the red-legged running frog, SVL: 45.10 mm; BM: 13.68 g) was lCT-scanned at 65 kV and 340 lA producing 1158 TIFF images at a resolution of 0.0493 mm/ voxel. K. maculata is a derived hyperoliid frog (nested within Neobatrachia and Ranoides; Pyron & Wiens, 2011) that thrives in varying terrain, and is capable of jumping, running, climbing and swimming (Ahn et al 2004;Porro et al 2017); this contrasts with the more basally positioned and almost exclusively aquatic X. laevis. Scan data from K. maculata were included to compare the unusual osteology of X. laevis with that of a taxon possessing a skeletal morphology and locomotor modes more typical of anurans.…”

“…Back muscles attaching to the pectoral girdle or forelimbs are discussed below. The back muscles of all frogs are externally (dorsally) covered by an extensive fascia dorsalis that attaches to the frontoparietal bone of the skull and spinous processes of the vertebrae (Ecker, 1889); in Xenopus, the posterior portion of fascia dorsalis thickens to become a ligamentous plate extending between the iliac shafts ( Fig M. coccygeosacralis is absent in Xenopus (Grobbelaar, 1924;P rikryl et al 2009); M. coccygeoiliacus originates along the urostyle and passes ventral to the sacrum to insert on the medial aspect of the ilium (Fig. 5B,E).…”

“…The most recent monographical description of X. laevis was nearly a century ago (Grobbelaar, 1924). Subsequently, certain anatomical regions have been described in varying levels of detail, including: the pelvic and proximal hind limb skeleton and musculature (Green, 1931;Dunlap, 1960;Palmer, 1960;Emerson, 1982;Van Dijk, 2002;Ro ckova & Ro cek, 2005;P rikryl et al 2009); the pectoral skeleton (Robovsk a-Havelkov a, 2010); the abdominal wall (Ryke, 1953); and the head skeleton and musculature (Paterson, 1939;Trueb & Hanken, 1992;Ro cek, 1993;Smirnov, 1994;Hass, 2001;Ziermann & Olsson, 2007;Gross & Hanken, 2008;Ziermann & Diogo, 2014), particularly with regards to development. Excellent dissection guides for frogs are available (Minkoff, 1975), including the classic work by Ecker (1889) that uses several species of the neobatrachid Rana as the basis for anuran anatomy.…”

Morphological and kinematic specializations of walking frogs

“…As seen in another specialized anuran walker, K. maculata maintains average jumping capabilities in comparison with other anurans (Porro, Collings, Eberhard, Chadwick, & Richards, 2017). In contrast, Astley (2016) found walkers tend to have inferior jump performance and shorter hindlimb lengths relative to body length.…”