Perucetus

Perucetus is an extinct genus of an early whale from Peru that lived during the Bartonian age of the middle Eocene. Perucetus is the largest Eocene whale, with length estimates varying from to . It was initially claimed to have rivaled or exceeded the modern blue whale in weight, partly due to the incredibly thick and dense bones this animal possessed, coupled with its already great size, but subsequent studies argued that it was significantly lighter. The ecology of Perucetus also remains largely mysterious. Based on the fossils, it was likely a slow-moving inhabitant of shallow waters. Its diet can only be speculated, but one suggestion proposes that it may have fed on benthic animals like crustaceans and molluscs living on the ocean floor. Only a single species is currently known, P. colossus.

== History and naming == Perucetus is known from a variety of bones; namely, thirteen vertebrae, four ribs, and some parts of the pelvic region. All bones are from the same individual (MUSM 3248) and were collected from the Yumaque Member of the Paracas Formation. The remains of the Perucetus are currently under protection and on display at the Natural History Museum of Lima, which belongs to the National University of San Marcos, the main institution of the team of Peruvian paleontologists involved in the discovery.