matched with the dentition of B. isis, suggesting a dietary difference between the two species, similar to that found in different populations of modern killer whales. It was probably an active predator rather than a scavenger. The discovery of juvenile Dorudon at Wadi Al Hitan bearing distinctive bite marks on their skulls indicates that B. isis would have aimed for the skulls of its victims to kill its prey, and then subsequently torn its meals apart, based on the disarticulated remains of the Dorudon skeletons. The finding further cements theories that B. isis was an apex predator that may have hunted newborn and juvenile Dorudon at Wadi Al Hitan when mothers of the latter came to give birth. The stomach contents of an elderly male B. isis not only includes Dorudon but the fish Pycnodus mokattamensis. Paleoecology Basilosaurus would have been the top predator of its environment. It lived in the warm tropical environment of the Eocene in areas abundant with sea grasses, such as Thalassodendron, Thalassia (also known as turtle grass) and Halodule. It would have coexisted with the dolphin-like Dorudon, the whales Cynthiacetus and Basiloterus, the primitive sirenian Protosiren, the early elephant Moeritherium, the sea turtle Puppigerus and many sharks, such as Galeocerdo alabamensis, Physogaleus, Otodus, Squatina prima, Striatolamia, Carcharocles sokolovi and Isurus praecursor. Extinction Basilosaurus fossil record seems to end at about 35–33.9 mya. Basilosaurus extinction coincides with the Eocene–Oligocene extinction event which happened 33.9 mya, which also resulted in the extinction of almost all other archaeocetes. The event has been attributed to volcanic activity, meteor impacts or a sudden change in climate (such as the environment getting cooler), the latter of which might have caused changes in the ocean by disrupting oceanic circulation. Basilosaurus went extinct leaving no descendants. Despite this new currents and deep ocean upwelling favored the diversification of modern cetaceans such as early toothed and baleen whales. Classification Below is the phylogenetic analysis on the placement of Basilosaurus. Two subfamilies exist in Basilosauridae: Basilosaurinae which includes Basilosaurus, and Dorudontinae. These groups have been declared invalid in the past. Dorudon remains were once thought to represent juvenile Basilosaurus. In popular culture The species B. cetoides is the state fossil of Alabama and Mississippi. During the early 19th century, B. cetoides fossils were so common (and sufficiently large) that they were regularly used as furniture in the American South. Basilosaurus is featured in the BBC's