Mes­sel Pit is the rich­est site in the world for under­stand­ing the liv­ing envi­ron­ment of the Eocene, between 57 mil­lion and 36 mil­lion years ago. In par­tic­u­lar, it pro­vides unique infor­ma­tion about the ear­ly stages of the evo­lu­tion of mam­mals and includes excep­tion­al­ly well-pre­served mam­mal fos­sils, rang­ing from ful­ly artic­u­lat­ed skele­tons to the con­tents of stom­achs of ani­mals of this peri­od.