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You Otter Know

Siamogale melilutra.

Photo: Mauricio Antón

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Otters are cute, cuddly critters, right? Well, research by Z. Jack Tseng, assistant professor in the Department of Pathology and Anatomical Sciences, shows that might not always have been the case. Six million years ago, a gigantic otter named Siamogale melilutra roamed the wetlands of southwest China and was likely one of the top predators of its time.

It’s all relative:

Sizewise, Siamogale was roughly proportional to today’s gray wolf, and its jaws were similarly large. When Tseng and his research team analyzed the jaws of 10 living species of otters, they found that the larger the otter, the weaker the jaw. They assumed that Siamogale would follow this pattern—but it didn’t.

Zoom image: Common Otter [36 inches / 15 pounds] Gray Wolf [66 inches / 100 pounds] Siamogale (Extinct Giant Otter) [82 inches / 110 pounds] Common Otter [36 inches / 15 pounds] Gray Wolf [66 inches / 100 pounds] Siamogale (Extinct Giant Otter) [82 inches / 110 pounds].

Big jaws, bigger bite:

These computer-generated models* show the relative strain (indicated in red) put on the jaws of the giant river otter vs. those of Siamogale during biting. The latter’s jaws were six times sturdier than Tseng expected, indicating a formidable bite— which, together with the animal’s size, would have made it a fearsome hunter.

Zoom image: Computer-generated models of the Giant River Otter jaw bone and Siamogale (Extinct Giant Otter) jaw bone. Computer-generated models of the Giant River Otter jaw bone and Siamogale (Extinct Giant Otter) jaw bone.

* Jaws are scaled to the same size for display purposes only. The giant river otter’s jaw is actually smaller than Siamogale’s.

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