An analysis of an ancient skull reveals that ancient whales have teeth and gums. The finding suggests that the now friendly animals used to be ferocious predators.
The discovery of 34 million-year-old whale skull from Antarctica showed that whales acquire their baleens through a complex and gradual evolution process. It was previously thought that these animals developed their baleens in a more straightforward manner.
As it turned out, they first prey on larger victims, lost their teeth, forego biting and learn to suck, until the comb-like baleens structure are developed.
Now, the baleen whales feed through filtering massive small prey from seawater and their baleens work more like a strainer.
The ancient whale skull belongs to the Llanocetus denticrenatus and was found by Ewan Fordyce, a professor from the University of Otago. He discovered the remains during an expedition in Antarctica.
His finding is now believed to be the second-oldest baleen whale ever found. The skull matched the remains found during an earlier expedition done by American researchers in the mid-1970s. This means that the researchers were able to form the puzzle of bones that belonged to the same whale.
Fordyce examined the skull with Felix Marx from the Royal Belgian Institute of Natural Sciences.
Their analysis, published in the journal Current Biology, stated that Llanocetus denticrenatus is an ancient relative of the humpback and blue whales even if the ancient species seemed to be daunting predators.
The relatives, nevertheless, both have distinctive grooves on the roof of their mouths. These grooves contain the blood vessels that support the baleens of the present-day whales. In Llanocetus, those grooves are found around tooth sockets, suggesting a peri-dental blood supply to the gums instead of baleens.
Marx says that Llanocetus are huge with a total body length of about 8 meters. The species' teeth are also widely spaced. In the case of the skull found, the tooth has a tear suggesting that it was used to cut prey.
"Llanocetus was both large and a ferocious predator and probably had little in common with how modern whales behave," Marx explains.
Marx and Fordyce concluded that climate was a big contributor to the history of whale evolution, particularly the change from tropical to cooler weather condition. Possibly, when the weather changes to colder temperatures, the animals' nutrition cycles were altered as well. Hence, the species that the animals used to feed on might have evolved and whales adapted to these supply available to them.