Family & ScienceFact-checked August 7, 2026

The Dinosaur Whose Skin Turned to Stone

A teenager spotted a few tail bones in North Dakota sandstone. What came out of the ground had fossilized skin, toe pads, and clues to a dinosaur mystery scientists are still solving.

By Peace Garden Almanac Editorial Desk · Fact-checked August 7, 2026

The first clue was not a giant tooth or a complete skull. It was a line of tail bones poking from sandstone.

In 1999, 16-year-old Tyler Lyson was searching for fossils on his uncle’s ranch near Marmarth, in the far southwestern corner of North Dakota. The bones belonged to a duck-billed dinosaur called an Edmontosaurus. They were still connected in order (one vertebra after another) instead of scattered like loose puzzle pieces.

That alone made the find worth a closer look.

But the rock was holding back a much bigger surprise.

A five-year wait

Lyson understood that a large fossil should not be yanked from the ground. Removing one carelessly can destroy the very clues that make it valuable. A major excavation did not begin until 2004, five years after the discovery.

That summer, Lyson and a team of volunteers worked for eight weeks. They removed rock a little at a time and protected the fossil in enormous plaster jackets: the same basic idea as putting a cast around a broken arm, only much heavier. Excavation continued until 2006.

The team eventually recovered a nearly complete dinosaur in three main blocks. One block containing most of the skeleton weighed about 8,000 pounds. Another, holding the tail, weighed about 1,700 pounds. The fossil would later receive the catalog number NDGS 2000. It also received a name that was easier to remember: Dakota.

As preparators carefully uncovered the specimen, bone was not the only thing they found. A bumpy surface followed parts of the tail, limbs, and feet. The pattern recorded the dinosaur’s skin.

Dakota was a dinosaur “mummy.”

Stop: what does “mummy” mean here?

Dakota is not a complete dinosaur body with meat and organs sealed inside. It is not frozen, and its skin is not soft or flexible. Dakota is a fossil.

What makes the specimen extraordinary is that the shape and texture of skin survived in three dimensions, closely draped over the bones. Scientists can see small bumps in the skin and flattened pads beneath the toes. They have also reported traces of ancient molecules in the preserved skin and tendons.

But CT scans and fossil preparation found no muscles or internal organs inside. Those tissues disappeared during decay. The skin, bones, tendons, and nail coverings that remain have been chemically changed and preserved in rock over an almost unimaginable span of time.

So when someone says “dinosaur mummy,” picture a stone record of a dried body, not a sleeping dinosaur waiting to wake up.

Meet the animal beneath the mystery

Dakota lived near the very end of the age of dinosaurs, about 66 to 67 million years ago. Western North Dakota did not look like today’s open prairie. The rocks of the Hell Creek Formation tell of a warm, damp coastal plain crossed by rivers, with forests, ponds, and swamps.

Edmontosaurus was a hadrosaur, the dinosaur group often called duck-bills. Its snout was long and flattened. Behind that bill sat batteries of tightly packed teeth that worked together to grind tough plants. As old teeth wore down, new ones replaced them.

Large adults could reach about 40 feet long and weigh around four tons. Dakota appears to have been somewhat smaller and may not have been fully grown. Its broad feet ended in hoof-like nails, and thick pads would have helped carry its weight.

Those pads matter because bones alone cannot show exactly how a dinosaur’s foot met the ground. Dakota preserved part of the missing instruction manual.

The clue that changed the ending

For years, people often explained dinosaur mummies with one dramatic idea: the animal must have been buried almost immediately after death. Fast burial could protect a body from scavengers and decay.

Dakota did not fit that story.

In a 2022 study, four scientists examined the prepared fossil, CT scans, and sediment around it. The bones inside the hand were not squashed flat, yet the skin lay tightly against them. That meant the body had deflated before burial rather than being flattened afterward by the weight of rock.

Then there were the marks.

Punctures and scrapes appeared on the skin and bones of the forelimb, hand, and tail. Some marks on the arm have shapes consistent with the teeth of an ancient crocodile relative. Damage elsewhere may have come from other animals, but the evidence does not name every visitor to the carcass. The researchers found no signs that the injuries had healed, which means they happened around or after the dinosaur’s death.

Here is the surprising part: the scavengers may have helped save the skin.

Openings in the body allowed fluids and gases from decay to escape. Scavengers, small invertebrates, microbes, and other decomposers removed softer tissues from inside. The tougher outer skin could then dry and collapse around the bones. Researchers think this drying may have taken weeks or months before river sediment finally covered the remains.

Burial still mattered. It protected what was left and began the long process of fossilization. But Dakota’s skin may have survived because ordinary decay had emptied and dried the body first, not because an instant flood perfectly sealed an untouched dinosaur.

That is the scientists’ best-supported explanation today. It is a proposed pathway built from bite marks, CT images, and sediment rather than a video of exactly what happened. Future preparation may expose more clues.

A mystery that keeps changing

Dakota was discovered by a teenager, but discovery was only chapter one. The specimen took years to excavate, transport, prepare, scan, and study. More than two decades later, it was still helping scientists rethink how dinosaur skin can enter the fossil record.

That is how paleontology works. A fossil is not a trophy with one answer attached. It is evidence. New tools can ask new questions of the same old stone.

And sometimes the smallest-looking clue (a few bones weathering from a North Dakota hillside) opens a mystery 66 million years deep.

Word detective

  • Articulated: Bones that remain connected or arranged as they were in the body.
  • Desiccation: Drying out as moisture leaves something.
  • Edmontosaurus: A large plant-eating, duck-billed dinosaur that lived late in the Cretaceous Period.
  • Fossil: Preserved remains or traces of ancient life, such as bones, skin, footprints, or burrows.
  • Hadrosaur: A member of the duck-billed dinosaur group.
  • Taphonomy: The study of what happens to an organism from death through burial and fossilization.

Try this at home or in class

  1. Evidence or idea? Make two columns labeled “Observed” and “Inferred.” Put fossil skin, bite marks, and CT images in the first column. Put drying for weeks or months and more than one scavenger in the second. What evidence supports each inference?
  2. Build a deflation model. Lay a damp paper towel over a few toy blocks, then let it dry. Compare its shape with a towel dried flat. How does draping help explain why Dakota’s skin sits close to the bones? Do not treat the model as a perfect copy of fossilization. It demonstrates only one part of the idea.
  3. Design a museum label. Explain “dinosaur mummy” in 40 words or fewer without using the words “whole body.” Include one thing Dakota preserved and one thing it did not.

If you want to visit

Dakota belongs to the North Dakota State Fossil Collection, cared for by the North Dakota Geological Survey in Bismarck. Parts of Dakota are currently on regular public display in the hallway outside the Heritage Center’s Adaptation Gallery: Geologic Time, but the complete fossil is not. The Geological Survey says the main body block is not currently displayed and is sometimes shown during separately scheduled behind-the-scenes tours. Check the museum’s dinosaur exhibit page and the Geological Survey’s public events page before making a special trip. Our statewide guide can help you plan the Heritage Center into a longer North Dakota route; families crossing I-94 can use the four-day North Dakota-with-kids plan.

As of August 7, 2026, the museum lists hours of 8 a.m.–5 p.m. Monday through Friday and 10 a.m.–5 p.m. Saturday and Sunday. Holiday closures apply. Recheck before visiting: https://www.history.nd.gov/planvisit.html

Grown-ups’ source note

This story distinguishes direct observations (such as preserved skin, CT results, and feeding traces) from researchers’ interpretations. We avoided an older, simplified claim that Dakota had to be buried instantly; the 2022 study found no sediment evidence for unusual rapid burial and proposed a longer drying-and-deflation pathway. We also avoid calling the specimen preserved “flesh.” The study reports skin and related structures but says muscles and internal organs are absent.

Primary and institutional sources:

Museum details last checked August 7, 2026. Spot an error? Read our editorial standards and corrections policy.

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