Giant land mammal speed discussion thread

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So apparently adult giraffes lack an aerial phase in their gallop. Only juveniles have a brief aerial phase when they run.

Mitchell suggested that giraffes’ elongated appendicular skeleton delivers a “mechanical advantage” during locomotion, and Pincher speculated that long limbs facilitate fast running speed. Yet, despite their extreme cursorial morphology, giraffes are athletically challenged. For example, adult giraffes run and walk at modest speeds and lack an aerial phase in their galloping gait, conforming to the observation that the largest terrestrial animals are not the fastest.

www.pnas.org/doi/10.1073/pnas.2108471119

The observed speeds ranged from 3.4 to 6.9 ms⁻¹, with a mean of 5 ms⁻¹ (or Fr 1.35). Given that the individuals studied were of similar size, absolute speeds were analysed. Giraffes moving immediately slower than this speed range used the lateral sequence walking gait, consistent with previous observations in giraffes (Basu, Wilson & Hutchinson, 2019). In the adult giraffes studied, the observed running gait was a grounded rotary gallop (Fig. 4). Brief aerial phases were only observed in juveniles, and are not covered in the present analysis.

peerj.com/articles/6312/


In the latter study, the fastest speed the sample of giraffes ran at was close to 7 m/s. This may not necessarily be top speed, though. Even then, however, it's unlikely giraffes run faster than 11 m/s.

Furthermore, some other maximal speed estimates used for giant mammals seem excessive (e.g. 16.7 m s⁻¹ for 1000 kg giraffes versus ≤11 m s⁻¹ in Alexander et al., 1977; Basu et al., 2019a).

journals.biologists.com/jeb/article/224/11/jeb217463/269062

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Footfall patterns and stride parameters of Common hippopotamus (Hippopotamus amphibius) on land

Common hippopotamuses (hippos) are among the largest extant land mammals. They thus offer potential further insight into how giant body size on land influences locomotor patterns and abilities. Furthermore, as they have semi-aquatic habits and unusual morphology, they prompt important questions about how locomotion evolved in Hippopotamidae. However, basic information about how hippos move is limited and sometimes contradictory. We aimed to test if hippos trot at all speeds and if they ever use an aerial (suspended) phase, and to quantify how their locomotor patterns (footfalls and stride parameters) change with approximate speed. We surveyed videos available online and collected new video data from two zoo hippos in order to calculate the data needed to achieve our aims; gathering a sample of 169 strides from 32 hippos. No hippos studied used other than trotting (or near-trotting) footfall patterns, but at the fastest relative speeds hippos used brief aerial phases, apparently a new discovery. Hippos exhibit relatively greater athletic capacity than elephants in several ways, but perhaps not greater than rhinoceroses. Our data help form a baseline for assessing if other hippos use normal locomotion; relevant to clinical veterinary assessments of lameness; and for reconstructing the evolutionary biomechanics of hippo lineages.

peerj.com/articles/17675/