Dinosaur may have walked with a limp 150 million years ago

About 150 million years ago, a long-necked dinosaur walked across a sandy flat that now sits high above Ouray, Colorado.

Its feet sank into wet sediment, and those steps hardened into a looping line of fossil footprints that scientists are now reading in detail.

A new study of the trail shows that the animal walked in a tight loop, then headed off in almost the same direction it started.

A research team analyzed the continuous trail of footprints, known as a trackway, and found evidence that the dinosaur favored one side.

The work was led by Dr. Anthony Romilio, vertebrate paleontologist at The University of Queensland (UQ). His research focuses on how fossil footprints record dinosaur movement and behavior.

Dinosaur caught in a tight loop

The mapped path stretches roughly 313 feet across a single rocky surface near the summit of West Gold Hill.

From above, it appears as a graceful curve winding across the slab rather than a straight line of evenly spaced pits.

The West Gold Hill trail was most likely shaped by a sauropod. Giant dinosaurs in this group carried their mass on four column-like legs and could leave deep impressions in firm sand.

“While we may never know why this dinosaur curved back on itself, the trackway preserves an extremely rare chance to study how a giant sauropod handled a tight, looping turn before resuming its original direction of travel,” said Dr. Romilio.

Studying the tracks of extinct animals

Today the tracksite sits on U.S. Forest Service land reached by a steep hike along the Silvershield Trail above Ouray.

At the top, a reddish sandstone slab holds the line of footprints, exposed to sun, snow, and wind. Each track is a shallow, rounded depression – its edges softened by time, yet still deep enough for a boot to settle neatly inside.

The trackway contains only hind footprints, which suggests the animal’s back feet carried more weight here than its front legs.

Ichnology – the study of fossil footprints and other preserved traces – relies on clues like track spacing and depth to piece together how extinct animals moved.

In this field, experts analyze behavior captured and locked into ancient rock rather than bones.

Dinosaur trail mapped with drones

Modern teams use drone-based photogrammetry, a method that builds 3D models from many overlapping images. The approach lets researchers capture entire tracksites in a single digital sweep.

The technique also prevents trampling of the site and allows researchers to zoom, rotate, and measure the tracks without ever stepping on the fragile rock.

At West Gold Hill, Romilio’s team flew a camera drone only a few yards above the rock and captured hundreds of overlapping images.

From those pictures, the experts reconstructed a virtual surface where every footprint rim and floor could be measured to within a few millimeters.

“It has been challenging to document these footprints from the ground because of the size of the trackway,” said Dr Paul Murphey, a paleontologist at the San Diego Natural History Museum (SDNMH).

“With these images we generated a detailed 3D model, which could then be digitally analysed in the lab at millimetre-scale accuracy.”

Subtle changes in direction

Once the digital model was complete, the team traced the center of each footprint and used software to link them into a walking path.

This step-by-step analysis revealed subtle changes in direction and spacing that would be hard to see from the ground.

Tortuosity, the measure of how twisty a path is compared with a straight line, helped the researchers describe just how tight the loop really was.

Looking only at the loop section, the straight line distance between its start and end was almost zero even though the animal kept walking for more than 100 feet.

“This shift from narrow to wide step placement shows that footprint width can change naturally as a dinosaur moves, meaning short trackway segments with seemingly consistent widths may give a misleading picture of its usual walking style,” said Dr. Romilio.

Did the dinosaur walk with a limp?

Paleontologists look for uneven footsteps in fossil trails as clues to limping or unusual gait, a pattern of how an animal moves its legs.

Earlier studies on abnormal dinosaur tracks describe alternating short and long steps that point to limping animals.

“We also detected a small but persistent difference in left and right step lengths, of about 10 centimetres or 4 inches,” said Dr. Romilio.

That uneven spacing suggests one side carried weight differently from the other, although the cause is still uncertain.

The team cannot say for sure whether this represents a limp, a side preference, or a response to patches of softer ground beneath the surface.

Even so, it shows how carefully measured footprints can reveal the subtle behavior of a dinosaur.

The study is published in the journal Geomatics.

Image Credit: Dr. Paul Murphey

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