Overlooked Coryphodon ancestor: Ocepeia

The fossil skull
of Ocepeia (Fig 1) is missing a few bits and pieces, like the posterior mandible and anterior rostrum including teeth.

Figure 1. Little Ocepeia compared to the much larger Coryphodon from a bit later in the Palaeocene. DGS colors added here. ” data-image-caption=”

Figure 1. Little Ocepeia compared to the much larger Coryphodon from a bit later in the Palaeocene. DGS colors added here.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/06/ocepeia-coryphodon.skull588.jpg?w=263″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/06/ocepeia-coryphodon.skull588.jpg?w=584″ class=”size-full wp-image-93135″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/06/ocepeia-coryphodon.skull588.jpg” alt=”Figure 1. Little Ocepeia compared to the much larger Coryphodon from a bit later in the Palaeocene. DGS colors added here.” width=”584″ height=”665″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/06/ocepeia-coryphodon.skull588.jpg?w=584&h=665 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/06/ocepeia-coryphodon.skull588.jpg?w=132&h=150 132w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/06/ocepeia-coryphodon.skull588.jpg?w=263&h=300 263w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/06/ocepeia-coryphodon.skull588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />

Figure 1. Little Ocepeia compared to the much larger Coryphodon from a bit later in the Palaeocene. DGS colors added here. Is Ocepeia a juvenile or an ancestor? Or a juvenile of an ancestor? I don’t know.

When faced with this sort of problem
it’s a good idea to first apply DGS colors to the bones to see what you do have. Then apply DGS colors to tentatively restore the missing pieces BASED ON a reasonable Bauplan. In this case the much larger and a little later Coryphodon (Fig 1) provides that blueprint.

Now the two nest together
in the large reptile tree (LRT, 2338 taxa). Coryphodon was not mentioned in the papers introducing Ocepeia (Gheerbrant et al 2001, 2014).

If there’s a better match among tested taxa, let me know.

Coryphodon is from Late Paleocene North America, 55 mya.
Ocepeia is from North Africa, about 60 mya. There must have been an earlier undocumented time when their last common ancestor on one continent or the other bid farewell to its later relatives because the Atlantic Ocean separated the two.

You do the math. It’s speculation from here on out, but it seems Mesozoic to me.

Coryphodon eocaenus
(Owen 1845; Late Paleocene, 55mya; 2.5m in length; ) was originally considered a pantodont. It was one of the first large browsing mammals and like a hippo, it may have been an aquatic browser. Derived from a sister to Ocepeia (below), Coryphodon was related to Uintatherium, though it bore no horns.

Ocepeia daouiensis
(Gheerbrant et al 2001, 2014; Paleocene, 60 mya; 9 cm skull length) is from Morocco. Here it nests with Coryphodon The pneumatized skull contains many air spaces. Slightly larger skulls have larger canines and so are considered male, but may just be older. This specimen has only a tiny canine on a broken maxilla. The molar teeth are relatively large and the jugal deepens below the orbit, hiding the posterior molars in lateral view. Note the dorsal eyes, as in hippos. Ocepeia was found with aquatic taxa and was probably amphibious. The name Ocepeia derives from the initials of Office Chérifien des Phosphates (O.C.P.), the national Moroccan phosphate mining company.

This appears to be novel hypothesis of interrelationships.
If not, please provide a citation so I can promote it here.

References
Gheerbrant E, Sudre J, Iarochene M and Moumni A 2001. First ascertained African “condylarth” mammals (primitive ungulates: cf. Bulbulodentata & cf. Phenacodonta) from the Earliest Ypresian of the Ouled Abdoun Basin, Morocco. Journal of Vertebrate Paleontology 21(1): 107–118.
Gheerbrant E, Amaghzaz M, Bouya B, Goussard F and Letenneur C 2014. Ocepeia (Middle Paleocene of Morocco): The Oldest Skull of an Afrotherian Mammal. PLoS ONE 9(2): e89739. doi:10.1371/journal.pone.0089739
Owen R 1845. Odontography; a treatise on the comparative anatomy of the teeth. Hippolyte Bailliere, London, 655pp.