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The blue whale is the largest animal existing on the planet right now. It’s a marine mammal with a length over 33 meters and weighs more than 200 tons. However, its evolution has always been a mystery.

Tsai Cheng-hsiu, a Taiwanese PhD student in geology at the University of Otago in New Zealand took over a fossil of a whale left behind by a research team and discovered that it may be the ancestor of the blue whale, dating back to 25 million years ago.

UDN reports, the fossil was found in New Zealand 27 years ago and is a newly discovered species. The size of this fossil is only one-third of the blue whale, but has the same mandible of the blue whale. Not only is it the oldest fossil in the family of blue whales, it might also be the blue whale’s ancestor 25 million years ago. Tsai named it “Horopeta umarere" and published the research on the Journal of Mammalian Evolution this year.

Tsai says that discovering Horopeta umarere only adds one clue in the evolution process of the blue whale. Questions like, “How did the six-meter-long Horopeta umarere turn into the blue whale triple its size?" and “What came before the Horopeta umarere?" are in need of further research in order to be answered.

In Tsai’s article, he has further explains this discovery:

Different from the toothed whales (Odontoceti), the adult baleen whales (Mysticeti) have no teeth. They use the baleen as a tool for hunting food. The existing baleen whales have three different ways of feeding in general.

1. The gulp feeding of the blue whale family (Balaenopteridae). That is to open the mouth very wide to gulp in a lot of water, fish and shrimps.

2. The skim feeding of the bowhead whales family (Balaenidae). They open their mouths wide but not as wide as the blue whale family, and then swim forward to let the water and food flow into the mouth constantly.

3. The suction feeding of the gray whale family (Eschrichtiidae). They mainly feed on the base of the ocean. When they open their mouths, they will take a slurp to inhale small animals into their mouth, just like how we drink soup.

With the differences between these three main ways of feeding (It is worth noting that this is not absolute. Under different conditions, the whales can also switch the feeding modes), we can try to find the origin of the largest animal on earth.

Translated by Vic Chiang
Edited by Olivia Yang