Rupelian life

Cynodictis ("slender dog marten") is an extinct amphicyonid carnivoran which inhabited Eurasia from the Late Eocene subepoch to the Early Oligocene subepoch living from 37.2 to 28.4 million years ago, existing for approximately .

Aetiocetus is a genus of extinct basal mysticete, or baleen whale that lived , in the Oligocene in the North Pacific ocean, around Japan, Mexico, and Oregon. It was first described by Douglas Emlong in 1966 and currently contains known four species, A. cotylalveus, A. polydentatus, A. tomitai, and A. weltoni. These whales are remarkable for their retention of teeth and presence of nutrient foramina, indicating that they possessed baleen. Thus, Aetiocetus represents the transition from teeth to baleen in Oligocene mysticetes. Baleen is a highly derived character, or synapomorphy, of mysticetes,

Ginglymostoma (from the Ancient Greek words γίγγλυμος (gínglumos), meaning "hinge", and στόμα (stóma), meaning "mouth") is a genus of shark in the family Ginglymostomatidae. There are two members in the genus. Members of this genus eat small fish and crustaceans, and are commonly quite lethargic unless provoked. Members of this genus have the ability to suck in water in order to remove snails from their shells in a manner that can be described as 'vacuum-like'.

Halitherium is a dubious genus of extinct dugongid sea cow that arose in the late Eocene, then became extinct during the early Oligocene. Its fossils are common in European shales. Inside its flippers were finger bones that did not stick out. Halitherium also had the remnants of back legs, which did not show externally. However, it did have a basic femur, joined to a reduced pelvis. Halitherium also had elongated ribs, presumably to increase lung capacity to provide fine control of buoyancy.

Anomotherium is an extinct genus of manatee that lived in the shallow seas of what is now Northern Germany. Its closest relative is Miosiren. Fossils of the genus have been found in the Bohlen and Doberg Formations of Germany.

Simocetus (from simus, "pug-nosed", and cetus, "whale") is an extinct genus of toothed whale that lived during the Oligocene period, approximately , making it the oldest named toothed whale, although older unnamed toothed whales exist.