Three odd gaits in one brief video

Today I stumbled upon a video clip so packed with biological interest that I would recommend watching it before it vanishes from the Web: https://www.getaway.co.za/environment/aardvark-outwits-brown-hyena/, the location being https://en.wikipedia.org/wiki/Mabula_Game_Reserve.

We see an individual of the aardvark (Orycteropus afer, https://en.wikipedia.org/wiki/Aardvark) foraging in broad daylight, which is already exceptional because this is one of the most strictly nocturnal of large African mammals.

Then enters an individual of the brown hyena (Parahyaena brunnea, https://en.wikipedia.org/wiki/Brown_hyena), an ostensible specialist on scavenging and an exceptional sighting in its own right although this species is not strictly nocturnal.

Bear in mind that the protagonists are about like-size (brown hyena adult averages 40 kg), but with divergent morphological specialisations. The aardvark is the largest specialised eater of termites and ants on Earth, with extremely muscular legs and large claws. The brown hyena has bone-crushing teeth (see https://en.wikipedia.org/wiki/Brown_hyena#/media/File:Hyaena_brunnea_1zz.jpg) and extremely economical hindquarters in which the shortness of the hind feet is compensated by extreme swing of the tarsal joint (https://www.inaturalist.org/observations/33937313). The aardvark is designed to dig extremely rapidly whereas the brown hyena is designed to walk long distances on an empty belly.

Action: the brown hyena chases the aardvark at full sprint, apparently intent on killing it in defiance of any reputation as a mere scavenger. Can the bite of this 'postcarnivore', unaccompanied by any sharp claws, possibly subdue such nuggety prey?

The brown hyena catches up, but the aardvark manages to somersault down a hole, frustrating the would-be killer. Then, a group of the blue wildebeest (Connochaetes taurinus taurinus), an odd-looking species in its own way, chases the brown hyena off the scene, in a surprising show of aggression towards this 'mere scavenger'.

What interested me particularly is that this footage revealed one new gait every minute. These species can all gallop, but they are strangely divergent in the sequence of limb-movements when not sprinting - perhaps because they are so peculiar morphologically that they look like chimeras.

The aardvark seems like a badger-on-ballet-shoes with a conical tail, a tubular snout and hare-like ears. The brown hyena has a strangely sloping back and long neck, nosferatu-ears, and a cross-grained cape-like mane. The blue wildebeest also has a sloping back and a strange mane and tail. And each is odd in its locomotory gearing, although not necessarily rhyming with reason.

The aardvark is perhaps the only fully terrestrial, digitigrade mammal which uses a perfect cross-walk, the legs moving in diagonal pairs (see https://www.kimballstock.com/results.asp?db=a&txtkeys1=aardvark and https://creatures-of-the-world.fandom.com/wiki/Aardvark?file=Aardvark_fs.jpg). This has not been pointed out in the literature but is obvious once one develops a search-image for walking gaits.

The brown hyena has its own odd walk in that the 'hock' seems hypermobile (see https://www.inaturalist.org/observations/68997824 and https://upload.wikimedia.org/wikipedia/commons/b/be/Brown_Hyena_%28Parahyaena_brunnea%29_%286472940707%29.jpg). But what is really unusual is that, instead of trotting like other carnivores, it paces like a camel. (Watch for this after the aardvark vanishes and the brown hyena gives up on digging.) Also see https://www.earthtouchnews.com/natural-world/predator-vs-prey/guess-what-this-brown-hyena-had-for-dinner/.

And, for its part, the blue wildebeest is also more reluctant to trot than most other ungulates, gearing up from a walk straight into a canter (see https://videohive.net/item/wildebeests-walking-and-running/26412070 for a different species of wildebeest).

So here we have an expose of specialised gaits which have yet to be explained in adaptive terms. The aardvark has slowed down the trot to convert the same limb-movements into a walk. The brown hyena has speeded up its walk in replacement of any trotting gear. And the blue wildebeest has just skipped the trot, going from first gear straight to third.

'Go figure'.

Posted on Αύγουστος 02, 2021 1147 ΠΜ by milewski