A new species of extinct porpoise kept a stiff bottom lip, fossils reveal. Though closely related to living porpoises, Semirostrum ceruttii (artist’s illustration above), named for its finder, Richard Cerutti of the San Diego Natural History Museum, has a mandible shape never before seen in mammals. Its bottom jaw protruded 18 cm beyond the top one, making up 40% of the beak. Researchers found the specimen (inset) in rock formations along the California coast estimated to be between 1.6 million and 5 million years old.
This photo shows the skull and jaws of skimmer porpoise
Source: Huffington Post Green