According to researchers, an extinct whale that has just been analyzed is one of the heaviest animals that have ever lived on earth. The group led by Eli Amson from the Stuttgart State Museum of Natural History examined the approximately 39-million-year-old bones of the whale discovered in Peru and used them to draw conclusions about its mass. The weight of the animal is estimated at 85 to 340 tons, the team writes in the journal “Nature”.
The species with the name “Perucetus colossus”, roughly translated as “the colossal whale from Peru”, is a contender for the title of the “heaviest animal of all time”, said the Natural History Museum.
As the researchers also report in the study, the whales developed into gigantic animals earlier than previously thought. After examining the fossil whale skeleton, they assume that the early relatives of today’s whales, dolphins and porpoises lived entirely in coastal waters and had enormous body masses as early as about 39 million years ago.
New perspective on whale evolution
“The find changes the understanding of whale evolution,” said Amson. The new study shows for the first time “that the gigantic body masses of the whales were reached 30 million years earlier than previously assumed”. Previously, the evolutionary transition to true gigantism in cetaceans such as modern baleen whales had been considered a relatively recent event, around 10 million years ago.
“Perucetus colossus” combines a gigantic size with an extremely high bone weight, said the 34-year-old researcher. “This early whale drastically pushes the previously known upper limit of skeletal mass in mammals and aquatic vertebrates. It may also be the heaviest animal ever described.”
Like a diver’s weight belt
Over the course of evolution, extra weight has helped marine animals regulate their buoyancy and stay underwater, much like the weight belt used by divers. The enormous weight of the “Perucetus colossus” can be explained with the accumulation of additional bone mass on the outside of the skeletal elements and with a higher bone density.
The fossil of the “Perucetus colossus” was discovered ten years ago in the desert on the southern coast of Peru. Each vertebra in the find weighs well over 100 kilos, and the prehistoric whale’s ribs are up to 1.4 meters long. At 5 to 8 tons, the 20 meter long skeleton of the new species is two to three times as heavy as the 25 meter long skeleton of a blue whale on display in the Hintze Hall of the Natural History Museum in London.
To estimate the specimen’s weight, the recovered and prepared bones were scanned and their volume determined. The internal bone structure was assessed with core drilling. To reconstruct the body mass, the researchers used the ratio of soft tissue to skeletal mass known from living marine mammals. “With the resulting estimates of between 85 and 340 tons, the weight of the new species is in the order of magnitude of the blue whale or possibly more,” the Stuttgart museum summed up.
