Pygmy Right Whale (closest relative to Cetotherium)

Name Meaning:  Whale Beast

Geologic Era:  Miocene-Pliocene (possibly into the Holocene)

Location Found:  Florida

Size:  4.5-6 meters long

Estimated Range:  Eurasia and North America

Extinction Date:  End of Pliocene (modern relative may still survive)

Cetotherium did suffer from the status of being a wastebasket taxon.  Many primitive mysticetes (baleen whales) were labeled as Cetotherium.  The problem with this method is that many of these animals were known only from fragmentary remains.  Now, only two species are recognized as truly being Cetotherium.  The others have either been declared invalid species or have been reassigned to other genera and species.  

Cetotherium would have been relatively small by the standards of modern whales, but still would have been much larger than a human.  The damage on this vertebra is probably not due to predation.  This pattern of wear is typical of vertebrae found in rivers.  The processes are gone for the most part, but one can still see where they were.   

Cetotherium probably occupied a niche similar to dolphins.  Dolphins themselves are predators of smaller marine organisms, but are still subject to predation by larger animals such as orcas, large sharks, or sperm whales.  Many recovered Cetotherium vertebrae show compression damage, probably caused by predation.  Many modern sharks strike their prey from beneath, targeting the chest and abdominal area.  Such an attack would result in the whale being incapacitated or stunned, and would likely damage the vertebral column.  

Giant sharks such as Megalodon would not have been Cetotherium’s only worry.  A recent find of a raptorial sperm whale (now called Livyatan melvillei) would have given even Megalodon stiff competition for hunting.  Cetotherium itself would have fed on small organisms such as krill and plankton, as modern baleen whales do.  A filter feeder such as Cetotherium can easily sustain itself on small organisms, as long as it can get enough.  Counter-intuitive though it may seem, larger organisms than Cetotherium sustain themselves in this way.

It is possible the Cetotherium has a family member still alive and well.  The Pygmy Right Whale is thought by some zoologists to be the last remaining member of Cetotherium’s family.  Physically, the two animals are very similar, even being somewhat comparable in size.  However, the Pygmy Right Whale is very poorly studied.  There are several reasons for this.  First, its range is restricted to the far southern hemisphere.  Second, they are a relatively small whale, and are not actively targeted for whaling operations or for commercial whale watching tours.  Third, where most whales are detected when they breech for air or flash their tail flukes, the Pygmy Right Whale engages in neither of these habits.  This makes them difficult to locate, let alone study.  That being said, their population does not appear to be an any danger, mainly due to their small size.  

Cetotherium (right) next to Livyatan (raptorial sperm whale)

Image Credits:

Skeleton:  “Cetotherium” by Pavel Gol’din, Dmitry Startsev, and Tatiana Krakhmalnaya – http://www.app.pan.pl/article/item/app20120107.html. Licensed under CC BY 2.0 via Commons – https://commons.wikimedia.org/wiki/File:Cetotherium.jpg#/media/File:Cetotherium.jpg


Cetotherium with Livyatan: By Apokryltaros – Own work based on [1], CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10874888


Pygmy Right Whale:”Caperea marginata 3″ by Lycaon.cl – Own work. Licensed under CC BY 3.0 via Commons – https://commons.wikimedia.org/wiki/File:Caperea_marginata_3.jpg#/media/File:Caperea_marginata_3.jpg