Meeting Abstract

43.4  Tuesday, Jan. 5  A Comparison of Jumping Behavior in the Rocky Mountain Tailed Frog, Ascaphus montanus and Fire-bellied Toad, Bombina orientalis ESSNER, R.L.*; SUFFIAN, D.J.; REILLY, S.M.; Southern Illinois University Edwardsville; Southern Illinois University Edwardsville; Ohio University ressner@siue.edu

Rocky Mountain tailed frogs, Ascaphus montanus (Anura: Leiopelmatidae) are semi-aquatic anurans belonging to a basal clade that diverged from all other frogs (Lalagobatrachia) at least 170 mya. Leiopelmatids retain a suite of plesiomorphic morphological features, including nine amphicoelous presacral vertebrae, free ribs, epipubic cartilage, and a “tail-wagging” muscle. They are unique among frogs in their use of an asynchronous (trot-like) rather than synchronous swimming gait. Detailed studies of leiopelmatid jumping behavior are currently lacking. However, it has been assumed that all anurans jump in a similar manner (like ranid frogs) by rapidly extending hindlimbs during the propulsive phase and initiating a mid-air rotation during flight in order to land forelimbs-first. Recovery begins near mid-flight by protracting and flexing extended hindlimbs and protracting and extending forelimbs so they are positioned to absorb impact forces. We compared jumping in A. montanus with a basal lalagobatrachian, the fire-bellied toad, Bombina orientalis using high-speed video at 500 fps. The two frog species differed in the timing of key kinematic events and exhibited dramatically different landing postures. Bombina orientalis reflected the general lalagobatrachian condition of early hindlimb recovery and forelimbs-first landings. In contrast, A. montanus exhibited delayed hindlimb recovery and avoided forelimbs-first landings. We propose that the jumping behavior of lalagobatrachian frogs is derived and that the unique behavior of A. montanus represents the ancestral condition for anurans.