Two years ago I was exploring the San Diego Natural History Museum when a fossil skull stopped me in my tracks. The Pliocene bones were clearly those of a toothed whale, but the specimen wasn’t quite like anything I had ever seen before. The porpoise’s lower jaw jutted far ahead of the upper – a thick, bony “chin” that would make Bruce Campbell jealous. What was that prodigious jaw for, and how did it evolve?

I wanted to know more, but the exhibit was short on details. The extinct whale hadn’t been officially named, and why a porpoise would have such a peculiar profile was anyone’s guess. That’s why I was thrilled to see that Yale University doctoral candidate Rachel Racicot