One of the now extinct ancestors of the blue whale could surpass the record for the heaviest animal to have ever lived on Earth, according to a study published on Wednesday. The marine behemoth, called Perucetus colossus, whose first fossils were discovered in Peru in 2010, lived 39 million years ago. Its average weight was estimated at 180 tons by a team of scientists whose work is published in Nature.
They remain cautious in their conclusions, but “there is no reason to think that the specimen discovered in Peru was the largest of its kind”, Eli Amson, co-author of the study, told Agence France-Presse. “There is a good chance that some individuals have broken the record” of the blue whale, adds this paleontologist from the National Museum of Natural History in Stuttgart, Germany. What is certain is “that we are in the same range”.
A total of 13 gigantic vertebrae, one of which weighed nearly 200 kg, were found at the site, along with 4 ribs and a hip bone. It took years and many trips to collect and prepare the fossils, and even longer for the team of Peruvian and European researchers to figure out exactly what they were dealing with: a new species of Basilosauridae, an extinct family of cetaceans.
The current cetacean family includes dolphins, whales and porpoises. Their earliest ancestors lived on land and some looked like small deer. Over time, they migrated to water, and basilosauridae were the first cetaceans to adopt a fully aquatic lifestyle. To adapt to this change (and to be able to store more energy in particular), these marine mammals began to grow in size, an evolutionary process called gigantism. They reached their maximum body mass 30 million years earlier than estimated, according to the study.
Like other basilosauridae, Perucetus colossus had a “ridiculously small” head compared to its body, although no bones have been found to prove this, Dr. Amson said.