Ichthyosaurs in Nevada: The mystery of an ancient reptile fossil graveyard : Short Wave 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.

Fossil CSI: Cracking the case of an ancient reptile graveyard

Fossil CSI: Cracking the case of an ancient reptile graveyard

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An artist's reconstruction of adult and newly born ichthyosaur, Shonisaurus popularis, which lived during the Triassic Period. Gabriel Ugueto / Smithsonian hide caption

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Gabriel Ugueto / Smithsonian

An artist's reconstruction of adult and newly born ichthyosaur, Shonisaurus popularis, which lived during the Triassic Period.

Gabriel Ugueto / Smithsonian

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.

"It is incredible how many ichthyosaur fossils are present at this site—they're just tumbling out of the hills," said Neil Kelley, a paleontologist at Vanderbilt University.

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 at the site now known as the Berlin Ichthyosaur State Park, which raised the questions: Why were there so many adult ichthyosaurs, and almost nothing else? What could have killed them all?

"I was not prepared for how abundant fossils would be all over the canyon at many, many layers outside of the site [pictured here]", said Neil Kelley. "And that really transformed my thinking that this was not just about one group of animals that had an unlucky day, but really about longer term cycles of animals doing their thing, living in an environment over thousands of years." Nicholas D. Pyenson / Smithsonian hide caption

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Nicholas D. Pyenson / Smithsonian

"I was not prepared for how abundant fossils would be all over the canyon at many, many layers outside of the site [pictured here]", said Neil Kelley. "And that really transformed my thinking that this was not just about one group of animals that had an unlucky day, but really about longer term cycles of animals doing their thing, living in an environment over thousands of years."

Nicholas D. Pyenson / Smithsonian

The puzzle has perplexed scientists, including Neil and his colleagues at the Smithsonian, for decades. Was it a mass stranding? A natural disaster? A giant squid with a voracious appetite?

But Neil 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.

Listen to Short Wave on Spotify, Apple Podcasts and Google Podcasts.

This episode was produced by Brit Hanson, edited by Gabriel Spitzer and fact-checked by Anil Oza. The audio engineer was Maggie Luthar.