Predator-prey relationship between the largest sabre-tooth felid (Smilodon populator) and the largest litoptern meridiungulate (Macrauchenia patachonica), in South America in the late Pleistocene

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Felids ( evolved in the Old World.

Meridiungulates ( evolved in South America when this continent was still isolated, unconnected to North America (

When a land-bridge arose from North America to South America, about 2.7 million years ago (, felids met meridiungulates - and began to prey on them.

By the late Pleistocene, both the sabre-tooth felid Smilodon ( and the litoptern genus Macrauchenia ( had undergone gigantism in South America. This resulted in

Two decades ago, this is how the BBC ( reconstructed the scene:,vid:sap-lHLrMC0 and,vid:jLyMwPinGFE

Adults of Macrauchenia patachonica ( weighed about 1100 kg - similar to the extant rhinoceros Diceros bicornis (

Macrauchenia patachonica also resembled rhinos in retaining three toes on each foot.

However, M. patachonica was unlike any ungulate (

It combined the following:

Together, these oddities suggest that M. patachonica

Farina et al. (2005, and have suggested that the sideways evasive action was one of 'swerving', when chased by S. populator.

This seems reasonable enough, in as far as it goes.

However, what Farina et al. (2005) may possibly have missed is the following addition to the rationale.

It seems to be uncontroversial that

Based on this 'concensus view', plus an assumption that S. populator hunted alone, my original thought is as follows.

Crucial to evasion of this particular specialised predator would have been an ability not only to swerve, but more particularly to 'buck sideways', in order to shake the body of the felid off the body of M. patachonica.

Such dislodging of the predator would allow the prey animal to resume acceleration in an attempt to outdistance the pouncer.

Sideways bucking in M. patachonica would help to explain the odd configuration of the bones - particularly the upper limbs but also the feet (retention of three toes) and the neck (carried horizontally).

Extant ungulates buck mainly vertically, as best-illustrated in rodeos ( and and

However, this has limited effectiveness against e.g. Panthera leo, because the felid can latch on with the teeth as well as the claws, and up-and-down movement is difficult when the body mass of the predator exceeds a quarter of that of the prey.

Bucking sideways would tend to use the body mass of the felid against it, with only the traction of the claws to overcome.

Certain ungulates possess dermal shields ( and Equus quagga is an extant example, with reinforced hide on the haunches (please see comment below).

If M. patachonica possessed a dorsal dermal shield in addition to the adaptations mentioned above, then this would limit the traction of the claws in the first place.

However, this is probably unknowable, given that all litopterns ( have been extinct for thousands of years, leaving us with only bones, not skin.

Posted on August 14, 2023 11:00 AM by milewski milewski


@beartracker @maxallen


I have seen, over the years, dozens of photos of misaligned striping on the hindquarters of Equus quagga (, resulting from the healing of wounds from failed attacks by the lion (Panthera leo).

Panthera leo attempts to secure E. quagga by means of digging its claws into the haunches. However, this is often foiled by the thickened, plastic-like dermis, which tends to be impenetrable to the claws.

The slicing of the epidermis (, as the claws slip on the hide, results in misalignment of the stripes as the skin heals.

Once the naturalist has a search-image for this phenomenon, it is likely to be noticed repeatedly.

The following are a few examples:

Scroll in

In the following case, the dermal shield failed, but the animal escaped anyway:

Posted by milewski 11 months ago

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