illustration of large otter

Mauricio Anton

Enormous otters once roamed southwestern China

Six million years ago, the wetlands and river valleys of southwestern China were full of life: tapirs and small deer strolled the shores, and the waters brimmed with clams. Swimming and striding through it all was a huge otter—described today for the first time—that weighed in at around 50 kilograms, twice the size of today’s otters (see artist’s representation, above). That’s about the same as modern wolves and among the largest otters that ever lived. Scientists first unearthed the creature’s fossils, including limb bones and a severely crushed skull, from carbon-rich rocks around a decade ago. The team CT scanned the fossils and then used sophisticated software to digitally reconstruct the skull from more than 200 fragments. They couldn’t accurately gauge the creature’s length, because none of the fossils preserved its tail. But based on its skull length—about 21 centimeters—the researchers were able to estimate its hefty weight, they report online today in Journal of Systematic Paleontology. The researchers dubbed the creature Siamogale melilutra, thanks to similarities of the skull and teeth to both otters (lutra) and badgers (melis). The otter likely lived near and foraged in a shallow lake or wetland in a warm, humid climate, say the scientists. And unlike large land mammals in the region, whose dispersal northward was blocked by two broad rivers, these semiaquatic otters and their kin were able to spread unhindered; fossils of a similar species from approximately the same era have been unearthed at another site about 1400 kilometers to the northeast.