Why dinosaur footprints inspired paleontologist Martin Lockley

On November 25, paleontologist Martin Lockley passed at the age of 73. PopSci spoke with Lockley about his career studying dinosaur tracks and footprints earlier this year.

Rows of razor-sharp teeth. Femur bones the size of telephone poles. The towering skeleton of an animal taller than a giraffe. The replicas of dinosaur bodies and giant fossils housed inside natural history museums around the world are usually our first exposure to the long-gone world of these extinct animals. Their sheer size draws people of all ages into the lost world of dinosaurs. However, for paleontologist Martin Lockley, it was their dinosaur footprints and tracks that stole the spotlight and launched his paleontology career.

“People found footprints interesting, but they had this perception that they were not very useful for interpretation of dinosaur activity. I don’t know why that was. You don’t have to be an expert to realize that tracks are made by animals,” Lockley told PopSci by phone in October.

[Related: A newly discovered sauropod dinosaur left behind some epic footprints.]

Born in Wales in 1950, Lockley was a pioneer in the study of the dinosaur tracks and footprints preserved in rock formations around the world. He taught for over 30 years at the University of Colorado and published more than 1,000 peer-reviewed scientific papers, wrote 17 books. The dinosaur ichnogenus Lockleypus was named in his honor in 2018. Along the way, he earned multiple awards, including the University of Colorado Student Generated Award for Teaching and the Korean Presidential Citation for Contribution to Cultural Heritage Protection in 2020.

Lockley was also the driving force behind the preservation track sites including the Dinosaur Ridge tracksite in Morrison, Colorado. The protected site is now one of the premier dinosaur track locations in North America. He also helped build the University of Colorado’s Fossil Tracks Collection of roughly 3,000 original or replica specimens of footprints and trackways and 1,600 full-size footprint and trackway tracings of a variety of extinct species.

“Some of the more interesting sites were made by smaller animals and they’re not the more typical known dinosaur tracks. We found tracks of pterosaurs and even some other smaller reptiles,” said Lockley.

Martin Lockley making a tracing of some small tracks at the Dinosaur Journey Museum of the West in Fruita, Colorado. CREDIT: Julia McHugh.

Lockley’s work helped his fellow paleontologists understand what fossil footprints can tell us about dinosaurs and the world that they lived in.

“Martin created dinosaur footprint science,” colleague and curator at the New Mexico Museum of Natural History and Science Spencer Lucas tells PopSci. “Through his energy, drive, and his collaborative spirit he created a whole subdiscipline of paleontology.”

What trace fossils tell us

The footprints and tracks left behind by dinosaurs and other prehistoric animals are called trace fossils. These imprints can offer clues to how quickly an organism walked or ran and even what their skin may have looked like. Compared with the body fossils of bones to teeth, trace fossils contain evidence of the interactions that the animals had with their environment and can depict what the physical environment may have looked like. According to Lucas, they offer a more reliable way to estimate the speed of a dinosaur than analyzing the skeleton.

“If you go back to the first Jurassic Park movie, where that T-rex is chasing the Jeep, you’ve had people who’ve looked at skeletons and said they could run 30 miles an hour or something,” says Lucas. “You’ve had other people have said these big dinosaurs could not run so fast. The problem with T-rex is we don’t have any trackways. We’ve only found a few isolated footprints.”

The main dinosaur track site at Dinosaur Ridge in Morrison, Colorado. CREDIT: Dinosaur Ridge.

A T-rex trackway would be the best way to get a reliable estimate of the dinosaur’s speed while running. Trace fossils offer a glimpse of ancient animal behaviors, while body fossils tell us about their anatomy and structure. Having both types of fossils offers paleontologists the best comprehensive view of the dinosaurs.

“One of the most interesting things is why are there some formations that have only tracks or most tracks and very few bones, whereas others are mostly bones and very few tracks,” said Lockley. “It appears to have to do with preservation of certain conditions, whether it is wet or dry land that leads to good preservation of tracks in the formations, where others lead to more preservation of tracks.”

[Related: After 60 years, a mysterious Australian dinosaur just got downsized.]

According to Lockley, one of the enduring mysteries this next generation of dinosaur track hunters could solve is why certain species have left behind more bones than tracks, while others left behind more tracks and fewer physical specimens.

“Triceratops-like dinosaurs are very common as bones, but are rare as tracks,” said Lockley. “It does not appear to be related to size because we have other track sites in these formations that have large tracks. They’re still as common as other dinosaurs.”

How discoveries happen

Lockley was a lifelong student of nature who grew up searching for shells and fossils along the beaches of Wales. The son of the late ornithologist Ronald M. Lockley, his father encouraged him to “just go out and observe and trust your observations.” He took that advice with him to the United States where he saw the power of the “right place and right time” nature of scientific discovery very early. When he first arrived in Colorado in 1980, a student first suggested that Lockley visit a series of dinosaur tracks in Gunnison, southwest of Denver. The tracks would prove life-changing, as Lockley documented the then little studied or understood site. It turned out to be the largest dinosaur track site in North America.

“The discoveries that excited me most have been so serendipitous,” said Lockley. “They came about from just walking along a beach going to what looked like one thing and finding that it’s something completely different.”

Following footprints around the world

While North America is home to some of the largest number of fossil footprints in the world, Lockley’s work with prints took him far and wide. He explored fossil and track sites in China, South Korea, Spain, South Africa, Mexico, Bolivia, and the United Kingdom.

[Related: New dinosaur species is nicknamed Jurassic’s ‘smallest runner.’]

These footprints are good stand-ins for extinct animals, even if they are found on different continents. They also provide valuable information that bones or other remains wouldn’t necessarily reveal.

“Martin has been very international in scope,” collaborator and Columbia University paleontologist Paul Olsen tells PopSci. “He was working on some South Korean tracks and found that they had beautiful skin impressions. It wasn’t a surprise that it had that kind of skin, but we wouldn’t have known those details without the footprints,” says Olsen.

In addition to finding the tracks, Lockley devoted time and energy preserving these important parts of the fossil record. This includes navigating the politics needed to create UNESCO world heritage sites so that future generations wouldn’t lose out on these precious relics of the past. His peers cite Lockley’s dedication to preserving and promoting dinosaur tracksuits and footprints around the world as his legacy.