In the badlands of eastern Wyoming, the Lance Formation is a trove of prehistoric fossils. And one area in particular — a region less than 10 kilometers (6 miles) across — has provided scientists with at least half a dozen remarkably well-preserved dinosaur specimens complete with details of scaly skin, hooves and spikes.

The paleontologist Dr. Paul Sereno and his colleagues dub it “the mummy zone” in a new study that aims to explain why this particular area has given rise to so many amazing finds and define exactly what a dinosaur “mummy” is.

In the early 1900s, a fossil hunter named Charles Sternberg found two specimens of a large duck-billed dinosaur, Edmontosaurus annectens, in the Lance Formation. The skeletons were so pristine that Sternberg, along with H.F. Osborn, a paleontologis

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