The massive skeleton of an extinct megafauna, the Steller’s sea cow, was discovered on a Siberian beach this month. This rare find was made even more special, due to the skeleton’s near completeness.
Steller’s sea cows ( Hydrodamalis gigas) once flourished in the arctic waters of Russia’s Commander Islands, a group of 17 barren islands and islets in the Bering Sea. The species was likely extinct by 1768; a victim of overhunting, it was prized for its meat and hide.
This particular skeleton was found in the Komandorsky Nature Reserve, an ecological sanctuary that’s been submitted for inclusion on the World Heritage List. Russian researcher Marina Shitova, who has studied Komandorsky’s northern fur seals, first spotted the animal’s rib cage protruding through the soil.
Eight people exhumed the skeleton over the course of four hours. From end to end, it measured 17 feet, though its skull and several vertebrae were missing. Mature adults could reach lengths of 25 feet, and weighed between eight and ten tons. Apart from cetaceans, the Steller’s sea cow was quite possibly the largest mammal of the Holocene, which began roughly 11,700 years ago (and arguably ended at the start of today’s Anthropocene).
The complete skeleton of a nearly 10-foot-long sea cow was also discovered on Bering Island in 1987, the reserve says, but has since been disassembled.
Most of the Steller’s sea cows you’ll see in museums are composite skeletons—amalgams of various individuals. Currently, the Finnish Museum of Natural History in Helsinki claims to have the only displayed specimen that’s fully intact.
That the Steller’s sea cow survived to the 18th century is unique among megafauna with origins in the Pleistocene, which began 2.6 million years ago, and ended with the arrival of the Holocene. By that time, other Pleistocene species like the moa and ground sloth were long gone. These gentle giants found a niche in the Bering Sea, withstanding freezing temperatures thanks to generous blubber and a thick skin. They fed mostly on kelp, and lived in social family groups. The species was monogamous, according to reports from naturalists who observed them.
It has been said that Steller’s sea cows also mourned their dead, which was described by an explorer in 1751:
“It is a very curious evidence of their nature and of their conjugal affection that when a female was caught the male, after trying with all his strength, but in vain, to free his captured mate, would follow her quite to the shore, even though we struck him many blows, and that when she was dead he would sometimes come up to her as unexpectedly and as swiftly as an arrow. When we came the next day, early in the morning, to cut up the flesh and take it home, we found the male still waiting near his mate…”
Much of what we know about the species comes from 18th century manuscripts. The animal received its name from Georg Steller, a German naturalist who described the animal on a Danish-led, Russian Empire-funded expedition in 1741. While his writings have been invaluable to our understanding of the sea cow, Steller, at the time, did not understand the concept of extinction.
“It seems, therefore, very probable, that though known to be in existence not more than forty years ago, it must now be ranked among the list of beings lost from the animal kingdom,” wrote fellow German naturalist Georg Heinrich von Langsdorff in 1812.
Komandorsky officials intend to display the newly-discovered specimen in the reserve’s visitor center. They hope it will tell, and teach, the history of extinction on the Commander Islands to future generations.