Sperm whales and pygmy sperm whales are known among mammals for their unusually shaped heads. Unlike most vertebrates, which are bilaterally symmetrical, toothed whales have asymmetrical skulls that accommodate highly specialized organs used for echolocation and sound production.
An extinct pygmy sperm whale from the Pisco Formation of southern Peru, known from a fossil skull found in the mid-1990s in a horizon 6.3 to 5.6 million years old. The animal was about 2.7 m long and carried the most extreme facial asymmetry known in any cetacean, and possibly any mammal: both bony nostrils are shifted entirely to the left, and the snout angles down 31 degrees, the mark of a specialised seafloor feeder. Its name, huachafo, is Peruvian Spanish for bizarre or extravagant. News article: https://phys.org/news/2026-11-prehistoric-whale-reveals-extreme-skull.html