Type species: Eritherium azzouzorum
Age: early Late Paleocene; 60 million years ago
Eritherium is known primarily from a part of its palate and teeth. However it is among the oldest known Cenozoic mammal in Africa. It shares large characteristics with the early proboscidean Phosphatherium, 5 million years after Eritherium. Eritherium was a small mammal, about the size of a large rabbit or hyrax. Its teeth and dental pattern show strange relations with early hyraxes and African ungulates, two species of known condylarth mammals, and early macroscelideans or elephant shrews. It shows to be a very ancient relative that branched off from the proboscideans before Phosphatherium. With this mosaic of primitive and advanced characteristics so early in the Paleocene, Eritherium suggests that either the mammalian diversity developed shortly after the K-T extinction, or that the diversity happened during the Cretaceous. Genetic molecular clock evidence supports the latter hypothesis, while fossil evidence suggests the former.
Gheerbrant, Emmanuel "Paleocene emergence of elephant relatives and the rapid radiation of African ungulates" PNAS vol 106, no 26, 30 June 2009 pgs 10717-10721