Full Breakdown
First Adult T. rex Trackway Unearthed in North Dakota
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The Discovery
In 2025 high-school science teacher Kent Hups of Northglenn High School spotted a wedge-shaped protrusion while volunteering near Marmarth, North Dakota. The feature proved to be one of four three-toed footprints preserved in the Hell Creek Formation, a Late Cretaceous floodplain. The prints form a continuous 23-foot (?7 m) trackway of two left-foot and two right-foot prints, each about one metre (?3 ft) long. Researchers identify the trackmaker as an adult Tyrannosaurus rex based on size, shape, and the formation’s known T. rex record.
Background & Context
The Hell Creek Formation has yielded numerous T. rex skeletal remains, including Sue, Teen Rex, Gus, and Stan. Isolated adult T. rex footprints have previously been reported only from New Mexico and Montana. This find is the first known trackway—a sequential series of prints—attributed to a fully grown T. rex.
Data & Statistics
| Metric | Value |
|---|---|
| Age of trackway | ? 66.5 million years (Late Cretaceous) |
| Trackway length | 23 ft (?7 m) |
| Footprint length | ~1 m (?3 ft) |
| Stride length | ~13 ft (?4 m) |
| Estimated walking speed | 3.4–4.5 mph (?5.5–7.2 km/h) |
| Preservation | Calcium-carbonate-capped sandstone casts |
How the Prints Were Preserved
Scientists propose that water rich in bacteria flooded the depressions soon after the dinosaur walked away. Dissolved calcium carbonate precipitated within the footprints, cementing the sand into durable casts. Erosion later removed the softer surrounding material, leaving the raised three-dimensional casts visible today.
Official Statements & Responses
Tyler Lyson, senior curator of vertebrate paleontology at the Denver Museum of Nature & Science, emphasized that footprints capture a moment of behavior, allowing scientists to trace movement across the ancient landscape. Lead author Peter Falkingham, a palaeobiology professor at Liverpool John Moores University, noted that high-resolution 3D scanning enabled digital models and physical replicas of each print. Three of the four footprints were wrapped for planned helicopter extraction to the Denver Museum later this autumn.
On-the-Ground Reporting
The dig crew returned the next day and confirmed additional prints, establishing the trackway’s full extent.
Conflicting Reports & Gaps
Speed estimates vary slightly: some report 3.4–4.5 mph, others 3.5–4.5 mph. Both ranges stem from the team’s calculations based on stride length and footprint size. No other substantive discrepancies appear in the reports.
Verbatim Quotes
- “As a teacher, I'm always telling my students that science starts with curiosity, passion and careful observation. I never imagined that could lead me to a discovery like this.” — Kent Hups
- “I got out my tape measure, and I started measuring the angles and everything started to fit,” — Kent Hups
- “Bones tell us an enormous amount about these animals, but footprints capture a moment of behaviour.” — Denver Museum of Nature & Science