One giant step: first known adult T rex footprints found in North Dakota

The first known series of footprints from an adult Tyrannosaurus rex has been found in North Dakota by a team of scientists.

The 23ft-long trackway – consisting of four three-toed footprints, two left and two right – was first identified in the south-west of the state, in the dinosaur fossil area known as Hell Creek Formation, last year by researchers from the Denver Museum of Nature and Science in Colorado and Liverpool John Moores University in the UK.

The findings, which have now been published in a scientific journal, date from 66.5m years ago and are the first of their kind to be found and identified. While isolated footprints and juvenile, or related species, tracks have been found before, this is the first known series of footprints left by a wandering T rex.

“Bones tell us an enormous amount about these animals, but footprints capture a moment of behavior,” said Tyler Lyson, senior curator of vertebrate paleontology at the Denver museum.

“With a trackway, we can actually follow an animal as it moved across the landscape. That is incredibly rare for T rex.”

Each of the footprints is about 3ft (0.91m) long, with a stride of about 13ft (3.96m). The research team used high-resolution 3D surface scanning to document each footprint and create physical 3D reproductions. From this work, researchers were able to make a rough estimate that the animal was walking about 3.5-4.5mph – about the same as a brisk human walking pace.

The T rex, the most famous of all dinosaurs, lived about 66-68m years ago during the cretaceous Period, according to the known fossil record. The creatures, which stood 12-13ft tall, were among the last non-avian dinosaurs to walk the Earth before a mass extinction event wiped them out.

Three of the discovered footprints are set to be recovered by helicopter later this year and transported to the museum in Denver. The findings are a particular joy for the Colorado schoolteacher who stumbled upon the site.

“As a teacher, I’m always telling my students that science starts with curiosity, passion and careful observation,” said Kent Hups, who is a long-time museum volunteer and also co-authored the paper. “I never imagined that could lead me to a discovery like this.”