Four-legged whale skeleton found in Peru is 43 million years old

Newly published research sheds light on the ancestors of modern day whales, describing creatures that lived millions of years ago and, oddly enough, swam through water using four legs. According to the study, paleontologists discovered the skeletal remains of one of these creatures in a Peruvian cave back in 2011. The fossil has enabled researchers to better understand the evolution of modern whales.

The study comes out of the Royal Belgian Institute of Natural Sciences, which reports that the ancient whale skeleton dates back about 43 million years. In their early form, whales were four-legged creatures — hoofed mammals, to be precise — about the same size as a wolf. Whales evolved in southern Asia, slowly adapting from life both on land and in water to an exclusively aquatic existence.

The Peruvian whale ancestor fossil is the oldest of its kind discovered in the New World at 42.6 million years old. This represents the most complete whale ancestor skeleton ever discovered outside of Pakistan and India, helping answer questions about the creatures and their evolution.

The four-legged whale discovered in Peru had a tail, the first vertebrae of which is similar to the one found in other amphibious mammals, including otters and beavers. The whale ancestor may have propelled itself through water by swimming in a similar manner, according to the researchers, though they note that the last tail vertebrae hasn't been found yet.

The four-legged whales eventually evolved into a similar creature with reduced hind legs called basilosaurids, a key distinction being their solely aquatic nature. From there, the species branched off into two groups of whales: toothed whales and baleen whales. The full study with illustrations of the whale ancestor skeleton can be found here.