New species of the archaic odontocete Xenorophus

[VD231991]

A new species of the primitive odontocete Xenorophus was described recently:
https://phys.org/news/2023-11-reveals-clues-whales-dolphins-echolocation.html
https://www.mdpi.com/1424-2818/15/11/1154

Until the publication in 2002 of a paper by Robert Ewan Fordyce describing the new Oligocene odontocete Simocetus from western Oregon, the most basal archaic odontocetes were grouped into a single family, Agorophiidae. Notwithstanding the fact that Simocetus was placed in its own family when first described, Uhen (2008) recognized that Xenorophus, Archaeodelphis, and his newly described genus Albertodelphis constitute a distinct group of basal odontocetes, Xenorophidae.

Having read the new paper by Bob Boessenecker and Jonathan Geisler, while the description of Xenorophus simplicidens and new specimens of X. sloanii provide new information on the anatomy of Xenorophus and how it differs from other members of Xenorophidae, it also erects the new clade name Amblyoccipita for the odontocete clade comprising all odontocetes more derived than Ashleycetus, Archaeodelphis, Mirocetus, and Xenorophidae, but also the new clade Stegoceti to include all members of Amblyoccipitia more derived than Simocetidae.

Uhen, M.D., 2008. A new Xenorophus-like odontocete cetacean form the Oligocene of North Carolina and a discussion of the basal odontocete radiation. Journal of Systematic Palaeontology 6(4):433-452.

[Newt]

Very interesting. I've been trying to get a grasp on these Oligocene cetaceans that are sort of transitional between the well-known and much-discussed proto-whales and basilosaurids of the Eocene and the rather modern whales of the Miocene. This is useful.

I'm perplexed by the very localized distribution of xenorophids, so far known only from the western Atlantic. Large marine animals should be able to disperse easily, so why aren't they known from other sites? Maybe they've just been overlooked.