Scientists have found that a giant fossil at the age of 42.6 million years led a semi-aquatic lifestyle (it was found in marine sediments along the coast of Peru). According to the shape of the animal’s limbs, scientists can assume that it carried the weight of its four-meter body and walked on the ground. Other anatomical features, including a powerful tail and webbed feet, make it clear that the animal was able to swim well.
βThe evolution of whales is the best documented example of macroevolution from small hoofed mammals to the giants of the ocean that we know and love today,β says Dr. Travis Park from the New York Natural History Museum. “However, despite the fact that the fossils are well known at different stages, there are still questions about the routes of ancient whales – how did their population spread around the world?”
“Other findings from this time are more fragmented and less completed,” says Olivier Lambert of the Royal Belgian Institute of Natural Sciences, the first author of the study in Current Biology. He adds: “We think that whales fed in the aquatic environment, where it is easier to move.”
Recent evidence suggests that ancient whales could swim for several days and weeks and retain the ability to move on land.
βAlthough whale could swim, it still had small hooves on its upper and lower limbs. It was much better for seals to move over land, βsays Park. The sharp teeth and the long muzzle of the animal indicate that ancient whales may have fished or crustaceans.
Earlier, more ancient remains of whales, dating back 53 million years, were found in India and Pakistan. Scientists argued when and how whales appeared near the Americas. Now we can roughly set the time when the first whales crossed the South Atlantic. This movement was facilitated by the western currents and the fact that the distance between the continents was half that of today.
The last few caudal vertebrae of the skeleton are lost, so it is unclear whether the creature on the tail had a large fin. This fin allows some modern whales to reach speeds of over 48 km per hour.
According to Lambert, it is likely that the whales returned to dry land in order to produce offspring. The first fully aquatic whales date from about 41-35 million years BC and fill a niche that remained free about 66 million years ago, when the last sea reptiles died out along with land dinosaurs.
By author Milena Moskvich