Paleontological discoveries have made it possible to point out that whales originated, some 50 million years ago, in Pakistan and India. Peregocetus is the most complete quadrupedal Evolution whale skeleton found outside this area and the first known of the Pacific region and the Southern Hemisphere.
To learn details of the important discovery, Mongabay Latam spoke with Olivier Lambert, a paleontologist at the Royal Belgian Institute of Natural Sciences and leader of the team that carried out the research, and with Rodolfo Salas, head of the Department of Vertebrate Paleontology at the Natural History Museum de Lima and co-author of the study.
The fossil was discovered by Mario Urbina, researcher and collector of the Museum of Natural History, in Lima. Mario Urbina continually explores in the deserts of Ocucaje, in the department of Ica, in search of fossils. The paleontological richness of the region is widely known, but this time Mario was looking for fossils in an unexplored area that has very old rocks.
Part of the fossil was observed on the surface, such as the teeth, part of the jaw and some phalanges. The rest of the skeleton appeared progressively as we removed sand and rock from the surface. After having delimited and identified all the bones preserved from the skeleton, we took photographs and videos.
The collection was made in blocks that included rock and some associated bones. The blocks were protected with plaster and jute to transport them to the Museum. After a week we finished with the collection.
Yes, this animal is a type of ancestral cetacean of 42.6 million years old, when the whales and dolphins had not yet evolved. This animal still had front and hind legs and could still walk on land.
Thanks to fossils discovered in Pakistan, India and North Africa, we know that cetaceans evolved some 53 million years ago in this region from terrestrial mammals called artiodactyls. Artiodactyls include, among other animals, the hippopotamus and pigs, so it is known that cetaceans and these animals are related.
It is estimated that Peregocetus was about 4 meters long. The shape of the bones of the legs, pelvis and tail allowed the researchers to determine that this whale was capable of living both on land and in water. The tail was long and its bone structure was similar to that of an otter or a beaver.
The feet were formed by long fingers that culminated in hooves, which show has supported the weight of the animal on land. The long fingers were probably joined by membranes, which would have benefited their propulsion in the water.
We are currently working on several projects that explore the evolution of the coastal ecosystems of the Southeast Pacific, mainly using the fossil record of marine vertebrates to make interpretations about environmental and climatic changes.
The fossil is in the Collection of the Department of Vertebrate Paleontology of the Natural History Museum of the National University of San Marcos, Lima, Peru. At the moment it is not on display, but we are planning a temporary for the next months.