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Twenty-million-year-old tusked sea cow is Central America's oldest marine mammal

An "emergency fossil excavation" due to rising water levels yielded a remarkably complete skeleton of an ancient sea cow, estimated to be about 20 million years old, the first evidence of a marine mammal from the Pacific side of the canal. The fossil skull, vertebrae, ribs and other bones belong to a new genus and species, Culebratherium alemani, a tusked seagrass-grazing relative of modern dugongs, which live in the warm coastal waters of the Indo-Pacific. C. alemani was a powerful eater. The researchers propose that its thick neck muscles, tusks and downward-pointing snout were adaptations for digging pits in the ocean floor to get to the underground stems of seagrass, the plants' most nutritional parts. Shown here: Some C. alemani molars showed signs of heavy wear while the newest molars had only recently emerged in the young dugong. Unlike manatees, dugongs do not continuously develop new teeth through adulthood.

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