“A journey of a thousand miles begins with a single step.” This old adage represents the study of fossil tracks. A single footprint gives you access to a world of information about the long-gone era of dinosaurs. Follow along as we look at some of the most fascinating dinosaur tracks discovered to date.
Fossilized Dinosaur Tracks
While most dinosaur fossils are mineralized bones, there’s another type of fossil that doesn’t get as much attention. Dinosaur footprints and trackways belong to this type known as trace fossils or ichnofossils. All marks or impressions made by ancient animals when they were alive are trace fossils.
Other examples of trace fossils include:
- Eggs, nests
- Fossilized poop (coprolites)
- Gizzard stones (gastroliths)
- Trails, burrows, borings
- Tooth marks
Body fossils, such as bones, teeth, and claws, are the preserved remains of dead creatures. These are tangible proofs of the animal’s existence, providing a great deal of information about its anatomy.
By contrast, fossil footprints were made by living, moving creatures (often a few moments before they died). And therefore are explicit clues to the animal’s behavior and life habits. The study of trace fossils, particularly dinosaur tracks, is called Ichnology.
Dinosaur Footprints and Trackways
A series of two or more tracks made by the same dinosaur is called a trackway. The dinosaurs that made them may have been looking for food, searching for mates, or just passing through. But one thing was sure: they were alive at that moment.
What’s impressive about fossil tracks is that they give us a peek at the life activities of these prehistoric reptiles – including how fast and heavy they were, who attacked who, and whether they roamed in packs. Something that bones alone can’t provide.
For instance, the famous dinosaur track site near Glen Rose, Texas, shows a group of trackways made by sauropods (long-necked plant herbivores) and theropods (walking and flying (carnivores).
The sauropod trackways parallel each other, suggesting that these dinosaurs traveled in herds. Meanwhile, the theropods are believed to be stalking (not attacking as previously thought) the traveling sauropods.
How are they formed?
Fossilization is a long and complicated process. Like body fossils, tracks are not immune to erosion, weathering, and removal by other organisms. Natural causes quickly destroy almost all traces on exposed surfaces.
Preservation of dinosaur tracks depends on many factors. But for a track to be fossilized, it must be buried quickly in the right type of environment.
The process works like this:
- A dinosaur walked across a mudflat, leaving footprints in the wet sediment.
- The coming tides covered the tracks with sand, grit, and gravel, protecting them from the detrimental effects of sun, wind, and water.
- The footprints were buried deeper due to sediment accumulation and hardened into rock through lithification.
- The fossil tracks might then be exposed after millions of years when erosion and weathering remove the sediment covering the tracks.
Paleontologists gather information not just from the original footprint (true track) but from the sediment (natural cast) that filled the impression and the dent (undertrack) in the layer of sediment beneath the true track.
Where to find them?
Dinosaurs left imprints of their existence all over the world. To preserve a track, it must be deposited under certain conditions. The ground must be soft enough to receive an impression but not too wet to destroy it. And there should be enough time for the imprints to harden.
That’s why most fossil footprints are found in bodies of water and dunes than in other environments. They are usually preserved in:
- Riverbeds and sandflats
- Shorelines and tidal lagoons
- Lakes, deltas, and floodplains
What can they tell us?
Dinosaur tracks are valuable to scientists because they explain how these extinct creatures lived. They can provide information about the trackmaker’s identity, size, speed, posture, and behavior, as well as the environment where they once thrived.
While it’s impossible to know the natural complexities of dinosaurs’ behavior, we learned a lot about them from their tracks.
- Some types of dinosaurs traveled in herds. Others hunted alone, and some opportunists or scavengers hunted in packs.
- Dinosaurs didn’t drag their tails on the ground when they walked.
- We can tell whether a dinosaur was walking or running based on the depth of its footprints.
- Dinosaurs can stand upright like elephants.
- Dinosaurs lived on land. Previous research thought that such giant animals might have lived primarily on water.
- Carnivorous dinosaurs can run up to 27 miles per hour, as fast as the champion sprinter Usain Bolt.
It is difficult to match the dinosaur species with the tracks they made. Therefore, trace fossils are classified differently from fossilized bones or skeletons. One way of identifying a trackmaker is to study the size and shape of their toe impressions and to look at their claws. Some dinosaurs had three toes, while others had four toes with claws like knives.
Best Places to Find Dinosaur Tracks
When looking for dinosaur tracks, it’s essential to learn about their taxonomy. Scientists apply formal names (ichnogenus) to tracks because the trackmakers are often unknown, and such names are easier to remember than symbols or codes. But the actual trackmaker should not be confused with the track names.
For example, the track name Anchisauripus refers to a particular type of footprint, not to Anchisaurus, which is a plant-eating sauropod. In fact, a theropod most likely produced this footprint. Below are six of the best places to see actual dinosaur tracks.
Rocky Hill, Connecticut
The Dinosaur State Park in the small town of Rocky Hill is home to a large number of dinosaur tracks that a group of construction workers discovered. Some 500 tracks are enclosed with a geodesic dome to allow visitors to come and see them up close. The rest were reburied to protect them from degradation. Most of the tracks were from a theropod dinosaur, which was believed to be similar to a venom-spitting Dilophosaurus from the Early Jurassic.
Glen Rose, Texas
One of North America’s most famous dinosaur tracks site is located in Dinosaur Valley State Park, along the Paluxy River near Glen Rose, Texas.The tracks are said to belong to sauropods Astrophocaudia and Sauroposeidon, the theropod Acrocanthosaurus, and the ornithopod Tenontosaurus. They lived about 120 million years ago during the early Jurassic period. Around 45 new tracks emerged recently because of the severe drought that dried up the Paluxy river.
Dinosaur Ridge, Morrison, Colorado
More than 330 tracks and 37 trackways of ornithopod and theropod dinosaurs are scattered in this part of Denver. This place was once a beach along the coastline of a vast ocean. Rare two-toed tracks, believed to be made by Velociraptor and Utahraptor, were discovered here in 2015. It is the first evidence of raptors in Colorado and only the second in North America.
Hundreds of dinosaur tracks course through this area along the Connecticut River. The largest track, Eubrontes, was discovered in 1802, making it the first scientifically described dino footprint in history. The bird-like creature who made the tracks is possibly a Dilophosaurus, a close relative of the theropod Coelophysis.
Red Gulch, Wyoming
The fossilized tracks at the Red Gulch Dinosaur Track site were formed 160-180 million years ago during the Middle Jurassic. Over 1000 documented footprints are preserved in limestone sediment in the lower part of Sundance formation. Most of these are located in the large open space called “the ballroom.” The trackmaker is still unknown. But potential candidates are carnivorous theropods, as well as sauropods and ornithopods.
Purgatoire River, Colorado
Picketwire Canyonlands is the largest dinosaur track site in North America. More than 1900 tracks and 130 trackways were imprinted along the banks of the Purgatoire River. During the Jurassic Period, around 155 million years ago, this area was a freshwater lake frequented by sauropods (Diplodocus and Apatosaurus), theropods (Allosaurus), and ornithopods (Camptosaurus).
A footprint is formed when a dinosaur walks through wet or soft mud and leaves an impression behind. The process is similar to how a footprint forms when a person walks through sand or dirt. But for the marks to be preserved, they must be filled with sediments such as sand, mud, and small pebbles and allowed to harden into rock.
The highest number of dinosaur footprints is recorded in La Rioja, Spain. More than 9,100 tracks were studied, and still, thousands are yet to be documented. It is estimated that there may be more than 70,000 footprints in this hilly region.
Vague imprints were being passed off as “man tracks” in a dinosaur track site in Glen Rose. But despite numerous attempts, researchers did not find any genuine human footprints in the area. Instead, some of the alleged human footprints turned out to be distorted dinosaur tracks.