Quick Bite: Weird Whales and Swimming Sloths

Marine mammals are fascinating beasts. Whales, manatees, seals, otters...they've all gone back to the water and in the process evolved all kinds of spectacular adaptations to make a living in a soggy setting. Toothed evolved an ability to “see” the underwater world around them using echolocation - basically sonar - to track prey with high-pitched sounds and echoes. A 23 million years old fossil from South Carolina called Cotylocara shows toothed whales could echolocate early in their evolutionary history. A more surprising adaptation to life in the water was preserved with another new whale fossil from California. Called Semirostrum, the new whale has a huge underbite and long chin which was probably used as a sensitive probe to track down buried prey. Whales in the water are interesting, but not unexpected. Our final study examines how SLOTHS adapted to life in the ocean. Thalassocnus was a relative of giant ground sloths, a solidly terrestrial group of animals. A recent study showed how Thalassocnus gradually acquired thickened bones, a trait that has been observed in nearly every mammal that has gone back to the water. Even if it’s a weird animal to imagine clawing through the water, it adapted to that lifestyle in exactly the way paleontologists expect any mammal to get back to the water!