PETM, taxonomy Throughout the Cenozoic, deep-sea benthic foraminiferal communities have faced many periods of environmental turmoil. Three major, yet relatively gradual faunal turnovers occurred during the Eocene-Oligocene, middle Miocene and middle Pleistocene - all periods of pronounced cooling and increases in polar ice volume. In contrast, the PaleoceneEocene Thermal Maximum (PETM; ~56 Ma) – a transient global warming event or hyperthermal - is characterized by a rapid extinction of 30-50% of all deep-sea benthic foraminiferal species (Thomas, 1998; 2007). So far, the exact cause(s) of this severe extinction event that devastated bathyal and abyssal faunas is not known. It is likely that a change in food-web structure, affected by high temperatures, a decrease in the oxygenation state of the oceans, calcite undersaturation, primary productivity or ocean current circulation changes played an important role in the benthic foraminiferal extinction (BFE) and in the establishment of the opportunistic fauna that characterizes the PETM itself (Thomas, 1998, 2007). Historically, the earliest Eocene benthic foraminiferal associations were considered as a transitional fauna, recovering from the BFE and gradually recolonizing vacant niches and habitats. This transition from a Cretaceous-Paleocene Velascotype fauna into a typical Eocene Barbados-type fauna appeared to be characterized by the gradual appearance of new taxa (Tjalsma & Lohmann, 1983; Berggren & Miller, 1989). With the discovery of several Eocene hyperthermals similar to the PETM (e.g. Eocene Thermal Maximum 2; ETM2; ~53.7 Ma), the question arises of what role these events played in the development of early Eocene benthic communities. For instance, how did the impoverished benthic fauna cope with the environmental perturbations associated with these successive and smaller Eocene hyperthermals on short time scales? Did it become more or less sensitive to climatic and oceanographic changes? One can also wonder what the effects were on longer time scales. Did early Eocene hyperthermals hamper or stimulate recolonization of the benthic realm, and if so, in what way?