Pleistocene Cetotheriidae whales

[Joseph Fossil]

About a year ago while researching early filter feeding whales of the Miocene-Pilocene eras (23-2.5 Million Years ago), I came across an interesting fossil record of the small whale genus Cetotherium from after the Pilocene.

 

Note: By small, I mean small by plankton eating whale standards (4.5 meters (14.7 feet) in length).

 

The record was of fossils of a Cetotherium sp. (of the family Cetotheriidae) from Pleistocene formations in Baku, Azerbaijan dating to the Calabrian, Pleistocene (1.8-0.8 Million Years ago).

http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&taxon_no=36692&max_interval=Quaternary&country=Azerbaijan&is_real_user=1&basic=yes&type=view&match_subgenera=1

 

https://studylib.net/doc/7652725/the-finding-of--a-new-marine-mammal-in-the-ashperon-stage...

 

 

I currently know of only know of one confirmed member of the family Cetotheriidae that lived during the Pleistocene, Herpetocetus (grew up to 4.5 meters (14.7 feet) in length).

 

 

 

Image credit: https://onlinelibrary.wiley.com/doi/10.1111/zoj.12108 

 

It's also worth mentioning that the discovery of the late Pliocene to at least early Pleistocene Herpetocetus species was accomplished by the forum member @Boesse in 2013.

https://www.researchgate.net/publication/236077474_Pleistocene_survival_of_an_archaic_dwarf_baleen_whale_Mysticeti_Cetotheriidae

 

 

I'm wondering if this record of Cetotherium sp. In Pleistocene Azerbaijan is correct, what would it's implications be in the study of Pleistocene Aquatic Mammalian life of Central Asia (especially since the largest body of water around Baku (The Caspian Sea) has been landlocked since the Late Miocene 5.5 Million years ago and any possible whale species to have arrived and lived there until the early Pleistocene would have arrived at least right before 5.5 Million years ago)?

 

How accurate this paper about the Pleistocene Cetotherium of the Caspian Sea is? Also, again if it is, then while the rest of the Cetotheriidae died out by the early Pliocene (3.6 Million Years ago) (the Pygmy Right Whales placement in the family is still debated), what were the external ecological conditions that allowed the supposed Pleistocene Cetotherium sp. and other members of it's family like the Herpetocetus sp. from the Falor Formation of Pleistocene California, US, to survive into the early Pleistocene?

[Joseph Fossil]

@Boesse What do you think? 

[Boesse]

I am extremely doubtful. Prior to about 1990, 'Cetotherium' was used as a wastebasket taxon to contain all sorts of distantly related species of true mysticetes (Chaeomysticeti) that did not clearly belong in one of the extant mysticete families. Cetotherium is one of those names that was overused for identification purposes. Further compounding this is the lack of a photograph or description of the specimen. I have extremely low confidence in this record.

 

Given the age of this paper as well, I wouldn't be surprised if the dating is also wildly off.

[Joseph Fossil]

@Boesse I completely agree. It would be a fascinating record if true. But given the date the paper was published (1940) and the massive amount of knowledge the scientific community has gained on whale evolution since then, the Pleistocene Baku "Cetotherium" whale fossil likely belongs to a completely different genus of Pleistocene whale.