This mystery begins in 1952, in the Nevada desert, when a self-taught geologist came across the skeleton of a massive creature that looked like a cross between a whale and a crocodile. It turned out to be just the beginning. Ichthyosaurs were bus-sized marine reptiles that lived during the age of dinosaurs, when this area of Nevada was underwater. Yet paleontologists found few other animals here, which raised the questions: Why were there so many adult ichthyosaurs, and almost nothing else? What could have killed them all? Paleontologist Neil Kelley says that recently, there has been a major break in the case—some new evidence, and a hypothesis that finally seems to fit. Neil talked with Short Wave co-host Aaron Scott about his theory of the case, and why it matters to our understanding of the past.Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy