Scientists have found the fossilized remains of another giant whale – interestingly from about 40 million years ago, astonishing because previous estimates put gigantism in whales to be a much later development, about 5-7 million years ago. This new find is now shaking up what we know about whales.
In his paper published by Nature on the 2nd of August, paleontologist Giovanni Bianucci shares about this giant whale skeleton his team found in the Ica province, in southern Peru. Bianucci and his team have named it Perucetus colossus. The name aptly is a reference to where they found the bones (Peru), its identification as a whale (cetus), and its size (colossus). One of the keys to identifying whales is the vestigial hipbone, which was found along with vertebrae and ribs. By looking at the vertebrae, Bianucci’s team estimates that the full animal would be approximately 20 meters long. Interestingly though, the estimates for the weight may put the P. colossus over the weight of the blue whale.
The bones found were denser and thicker than typical whale bones in an adaptation known as pachyosteosclerosis. This is typically found in animals that live in shallows and/or with substantial amounts of blubber to resist the cold. This thickening was found in all of the bones recovered. The vertebrae were found to be almost twice the thickness of the vertebrae of a blue whale. The comparison to the now-extinct Stellar’s sea cow and other sirenians has been made, in terms of bone density which emphasizes the theory that this animal could have been a diving whale that occupied shallow waters. This adaptation allows for the weight necessary to dive for prey and to hold enough fat to resist cold waters – important as the dating places this whale during a period of global cooling. Regardless of the current estimates, many researchers are doubtful if P. colossus was truly heavier than the blue whale.
Behaviorally, there is little that can be confirmed by the fossils. There were no pieces of the skull found to confirm diet, but it has been hypothesized that this whale likely fed on fish as was typical for early whales or crustaceans because of its supposed diving capabilities. This is, of course, all speculation.
Although there is much to still be discovered about this new species, it is exciting to find an individual so outside of our understanding of whale evolution.
References:
Bianucci, G., Lambert, O., Urbina, M., et al. A heavyweight early whale pushes the boundaries of vertebrate morphology. Nature (2023).
https://www.cbc.ca/news/science/perucetus-whale-fossil-heavy-1.6925284
https://www.reuters.com/science/ancient-whale-peru-may-be-most-massive-animal-ever-earth-2023-08-02/