Fossil of an Extremely Large Whale Discovered in Peru; How Was Its Ancient Lifestyle Like?

A colossal ancient whale was uncovered by scientists, and it has the potential to set the record for the heaviest animal ever known to exist on Earth.

Gigantic New Species of Ancient Whale

The discovery of the colossal whale is the latest result of the intense search activity of a diverse group of scientists which began in 2006. Led by associate professor Giovanni Bianucci of the University of Pisa, the researchers explored the city of Ica in southern Peru.

The discovered extinct whale named Perucetus colossus was approximately 39 million years old. It is the new member of the basilosaurid family within the order Cetacea where dolphins, whales, and porpoises belong. The extracted remains are considered to be one of the most significant fossil vertebrate collections of the Cenozoic Era which occurred about 66 million years ago.

Perucetus colossus has an estimated body mass of 85 to 340 metric tons. This weight is equivalent to or even exceeds that of the blue whale which holds the current record of being the animal with the greatest body mass.

Its partial skeleton is estimated to be 17-20 meters long and is composed of 13 vertebrae, four ribs, and one hip bone. The fossilized remain is shorter than that of a blue whale that measures 25 meters long, but its skeletal mass exceeds that of the vertebrae of any known mammal or sea animal.

Perucetus exhibited thickening and heaviness of skeleton due to its extremely dense and compact bones. This property known as pachyosteosclerosis is shared by the ancient whale with sirenians or huge marine herbivorous mammals like sea cows, manatees and dugongs. It is not currently found in any living cetacean.

It is also believed that the ancient animal weighed two to tree times more than the blue whale which currently weighs a maximum of 149.6 metric tons. Bianucci also describes this animal to have three times the weight of a giant sauropod dinosaur Argentinosaur, 30 African bush elephants, and almost 5,000 humans.

Due to its huge body mass, Perucetus likely swam slowly in its coastal habitat. It also has an undulatory and anguilliform swimming style which means that its flexible body moved from head to tail in curvy waves. Scientists believe that the weight and size of the extinct whale were their evolutionary adaptations to survive shallow and agitated coastal waters.

Colossal Whale's Ancient Lifestyle

Based on the structure of its heavy bone, it is assumed that Perucetus must have had lighter tissues in order to acquire neutral buoyancy. The discovered specimen appeared to have achieved sexual maturity, although it might have still been growing as proven by the unfused ends of its vertebrae.

The researchers did not find the whale's skull or teeth, but its identified characteristics suggest that Perucetus likely fed near the seafloor and was not an active predator. This is an unusual feeding behavior compared with most whales which use their light skeletons in chasing fast-moving prey.

Meanwhile, study authors have three theories about Perucetus's diet. First, this animal might have been a plant eater like a sea cow. Secondly, it could have fed on tiny mollusks and crustaceans in sandy bottoms. Lastly, Perucetus might have been a scavenger of vertebrate corpses.