Spectember 2024 #02: Swimming Swine

An anonymous submitter asked for a “buoyant ungulate that runs atop the sea”:

A shaded sketch of a speculative semi-aquatic descendant of feral pigs. It's a long-bodied chunky hippo-like animal with short legs, wide paddle-like hooves, and a tapir-like head with a a short trunk, small high-set eyes, and small ears.

Pontoporcus plotus is a 1.5m long (~5′) amphibious pig descended from a feral population of domestic pigs left on a small tropical island. After inadvertently wreaking havoc on much of the local ecosystem, its ancestors eventually turned to a more marine-based lifestyle foraging along beaches and in coastal waters.

Naturally highly buoyant, Pontoporcus actually floats so well that it’s mostly limited to the water’s surface, unable to dive to any significant degree. But despite this it’s a fairly good swimmer, using broad hooves with wide fleshy pads to paddle itself along in an aquatic trotting- or running-like gait.

It forages both on land and in the water, mainly eating soft vegetation and marine plants, but much like its ancestors it will also opportunistically feed on whatever smaller animals it can catch or scavenge. Its semi-prehensile trunk-like snout is used to grasp at food items, to probe and root around in soft sediment, and as a snorkel.

Its hairless skin is very susceptible to sunburn, but it secretes a thick oily red-brown substance (similar to modern hippo “blood sweat”) that acts as a natural protective sunscreen.

These pigs are accomplished island-hoppers, regularly traversing the relatively shallow seas all along their island chain – but their natural flotation and long fat bodies also make them prime targets for large aquatic predators attacking from below, so these journeys tend to involve groups of Pontoporcus “running” along the sea surface aiming for their next destination as fast as they possibly can.

Island Weirdness #33 — Big Pigs & Tiny Buffalo

Located on the Pacific Ring of Fire, the islands of the Philippines were formed by volcanic activity at the junction between several tectonic plates. Most of the 7461 islands that make up the archipelago have never been connected to any other landmass, leading to a huge number of unique endemic species evolving from whatever managed to arrive via ocean rafting events.

A stylized illustration of an extinct giant pig. It has four long thick tusks and long legs..
Celebochoerus cagayanensis

Celebochoerus cagayanensis was a giant species of pig, known from the island of Luzon. Living around 800,000 years ago in the mid-Pleistocene, it had enormous tusks and stood around 1m tall at the shoulder (3’3″) — similar in size to the very largest modern pigs, the African giant forest hogs.

The giant forest hogs are also some of its closest living relatives, along with the river pigs, and back in the Miocene and Pliocene similar pigs were present in Asia. Celebochoerus‘ ancestors probably arrived in the Philippines from Taiwan, and eventually spread onwards to the Indonesian island of Sulawesi to the south, where another species of Celebochoerus existed.


A stylized illustration of an extinct dwarf water buffalo. it has short curved horns, drooping ears, and a chunky body.
Bubalus cebuenesis

In contrast to the huge pigs of Luzon, the Cebu tamaraw (Bubalus cebuensis) was a particularly tiny species of wild cattle related to modern water buffalo. Just 75cm at the shoulder (2’6″), it was an example of insular dwarfism even smaller than the modern tamaraw which still survives on the island of Mindoro.

The spotty fossil record of these animals makes it difficult to determine when they disappeared, but it’s likely that they went extinct sometime around the arrival of early humans about 700,000 years ago.

Kubanochoerus

Pigs were once unicorns.

Kubanochoerus gigas lived about 15-7 million years ago during the mid-to-late Miocene, and ranged across a large portion of Eurasia with fossils known from both Georgia and China.

It was one of the largest known pig species to ever live, slightly bigger than the modern giant forest hog at about 1.2m tall at the shoulder (3′11″). But its most distinctive features were its horns, with a small pair above its eyes and a single large forward-pointing one on its forehead.

A few specimens lack the large horn, and so some paleontologists consider it to be a sexually dimorphic trait possessed only by males. But it’s currently unclear whether this was actually the case, since at least one “hornless” skull has been reported with the distinctive larger tusks also associated with male pigs – so it’s possible that the horned and hornless Kubanochoerus were actually separate species!