Newly-discovered extinct whale may have been the heaviest animal ever

The animal’s bones had an unusually large volume and were also extremely dense, according to Reuters. This combination of thickening and densification of bones is called pachyosteosclerosis. The characteristic is absent in living whales, dolphins and porpoise. But it is present in sirenians, a marine mammal group that includes sea cows. The animal has been described in an article published in the journal Nature.

Whales that dive deep typically have the ability to completely empty their lungs to plummet into the depths of the ocean but P. colossus probably lived in shallow coastal areas. This would mean that it probably dived with air in its lungs. But diving with air in the lungs would make it quite difficult to stay near the seafloor—that is where the very heavy bones come in. The skeletal mass of P. colossus would have been between five and eight tons, which is twice that of the blue whale.

“Its fat, bloated body may have been more like that of a sirenian than of any living whale. Among sirenians, due to its giant size and probable similar lifestyle, it could recall Steller’s sea cow, discovered in 1741 and exterminated by humans a few years later,” Giovanni Bianucci, lead author of the study, to Reuters. Bianucci is a palaeontologist at the University of Pisa in Italy.