Locomotion and postures of the Vietnamese pygmy dormouse Typhlomys chapensis (Platacanthomyidae, Rodentia): climbing and leaping in the blind

Gait mechanics of a blind echolocating rodent: Implications for the locomotion of small arboreal mammals and proto‐bats

“…This most likely implies that a stable and secure situation does not require intense visualization of the surrounding available substrates. In this study, we demonstrate that the Vietnamese pygmy dormouse is capable of achieving spatiotemporal gait mechanics similar to other small‐bodied arboreal species through the use of ultrasonic echolocation to collect information about the environment instead of vision (Youlatos et al, 2020). Individuals were capable of successfully moving across all five substrate conditions and adopted similar strategies as other species in response to both substrate and speed variation.…”

“…Recent evidence suggests that the Vietnamese pygmy dormouse has very poor eyesight, unable to perceive the surroundings and instead uses echolocation to “visualize” its arboreal environment (Panyutina et al, 2017; Volodin et al, 2019). Youlatos et al (2020) demonstrated that the emission of echolocation pulses by the Vietnamese pygmy dormouse increases during locomotion and also shows a link to the type of substrate. In contrast, acoustic activity does not differ substantially during non‐locomotor (i.e., postural) behavior regardless of substrate.…”

“…While there is considerable debate about the relative importance of the visual system specifics (e.g., forward‐facing eyes with large binocular fields), there is a little doubt that the ability to at least see the environment must confer some level of safety when navigating arboreal substrates (Heesy, 2009; Martin & Ross, 2005; McVea & Pearson, 2009; Shepherd & Platt, 2006). In this study, we explore biomechanical strategies of arboreal locomotion in the Vietnamese or Chapa pygmy dormouse ( Typhlomys chapensis ; Osgood, 1932), a blind rodent that uses ultrasonic echolocation to navigate in tree canopies (Panyutina et al, 2017; Volodin et al, 2019; Youlatos et al, 2020).…”

“…Moreover, the Vietnamese pygmy dormouse is characterized by regression of the gene for the interphotoreceptor retinoid‐binding protein, which plays an important role in vision (Cheng et al, 2017). To navigate through its environment, the species has developed a unique system of ultrasonic echolocation for beyond‐tactile orientation during locomotion (Panyutina et al, 2017; Volodin et al, 2019; Youlatos et al, 2020). The ultrasonic vocalization of the Vietnamese pygmy dormouse is reminiscent of bat echolocation calls, yet the sweeps in this rodent are faint (Panyutina et al, 2017; Volodin et al, 2019).…”

“…The ultrasonic vocalization of the Vietnamese pygmy dormouse is reminiscent of bat echolocation calls, yet the sweeps in this rodent are faint (Panyutina et al, 2017; Volodin et al, 2019). This unique adaptive mechanism appears to facilitate arboreal faculties, including confident progression through an unfamiliar environment, over arboreal substrates, as well as aimed leaps from branch to branch (Panyutina et al, 2017; Youlatos et al, 2020). Currently, no information is available as to whether the use of echolocation by the Vietnamese pygmy dormouse influences quadrupedal gait mechanics on arboreal substrates.…”