High in the Three Sisters mountains of the Cascade Range in central Oregon, researchers had to hike—and then ski—to get to the quiet ephemeral pool. Strange-looking salamanders, and not much else, lived in the water.

“I noticed right away that the [salamander] larvae were really skinny and big-headed,” says Susan Walls, now a research biologist with the United States Geological Survey. When she looked closer, she could see that the heads and jaws of this population of long-toed salamanders were much bigger than normal. It turns out that these larger mouths served a very specific purpose: cannibalism.

In one of the first research papers on this subject featuring salamanders, Walls had described how these larger jaws also held bigger vomerine