Was the massive predator Andrewsarchus a wolf, a pig, or a hidden whale relative?

Nature · Published 3 October 2026 Swipe more like this →

In short: For a century, paleontologists have struggled to classify Andrewsarchus, a giant carnivore with a skull over two feet long. Once hailed as the world's largest land predator, its true identity remains a puzzle. Is it a wolf-like mesonychid, a pig-like entelodont, or a mysterious cousin to modern whales?

Discovered in 1923 by Kan Chuen-pao in Inner Mongolia, the holotype skull of Andrewsarchus mongoliensis remains the most complete fossil of this enigmatic creature. Found in rocks dating between 37 million and 47 million years ago, the specimen was initially described by Henry Fairfield Osborn in 1924. Its sheer scale—with a skull measuring over 2.7 feet—led early researchers to label it the largest terrestrial carnivore ever discovered. However, these early size estimates, which suggested a length of over 12 feet and a height of 6 feet, were based on the proportions of mesonychids, a group of extinct, hoofed predators. Modern reassessments suggest these figures were likely inaccurate.

The animal's classification has shifted repeatedly as paleontologists analyzed its anatomy. Initially, Walter Granger compared the skull to the pig-like Entelodon, while William Diller Matthew argued it was a mesonychid, or 'wolf with hooves.' By the late 20th century, some experts hypothesized it might be a land-dwelling relative of whales. Today, the consensus places Andrewsarchus within the artiodactyls—the same group that includes modern camels, pigs, hippos, and whales. This connection is supported by specific dental features, such as the wrinkled cusps on its cheek teeth, which resemble those of pigs.

Despite its fearsome appearance, the creature's lifestyle remains debated. While its teeth were suited for piercing and crushing, the skull shows signs of wear from heavy chewing, and a reduced sagittal crest suggests a weaker bite force than one might expect from a top predator. Some researchers now suggest it may have been an omnivore or a scavenger rather than a hypercarnivore. Because the fossil record for Andrewsarchus is limited mostly to skulls and teeth, and the holotype itself is damaged, its exact position on the mammalian family tree remains a subject of ongoing scientific investigation.

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