The stomach contents of ancient whale Basilosaurus isis suggest it was an apex predator, according to a study published January 9, 2019 in the open-access journal PLOS ONE by Manja Voss from the Museum für Naturkunde Berlin, Germany, and colleagues.
The authors uncovered an adult B. isis specimen in 2010 in the Wadi Al Hitan (“Valley of Whales”) site in Cairo, Egypt. This site was once a shallow sea during the late Eocene period and is remarkable for its wealth of marine fossils. While excavating this main B. isis specimen, the authors also revealed the remains of sharks, large bony fish, and, most numerously, bones from Dorudon atrox, a smaller species of ancient whale.