What Fossil Trackways Teach Us About How Dinosaurs Moved
A skeleton can tell you a great deal about an extinct animal's size and rough proportions, but it can't tell you how that animal actually moved — whether it habitually walked, whether it could break into a run, how its legs swung underneath its body. For that, paleontologists turn to a different kind of fossil entirely: not bone, but the trace an animal's foot left in soft ground that later hardened into stone. The study of these trace fossils is called ichnology, and it's essentially tracking applied to deep time.
How a footprint becomes a fossil
A trackway fossilizes the same way a modern print in mud can survive if conditions cooperate: an animal steps into soft sediment — mud, sand, volcanic ash — leaving a clear impression, and that impression is then covered by another layer of sediment before rain, wind, or another animal's feet can erase it. Over enormous spans of time, the layers compress into rock, preserving the print's shape as a permanent record. It's a much rarer event than a bone fossilizing, which is exactly why a well-preserved dinosaur trackway is treated as such a valuable find — sites like Dinosaur State Park in Connecticut, the Paluxy River tracks in Texas, Cal Orcko in Bolivia, and Lark Quarry in Australia are each famous for exactly this kind of preservation.
What a single track reveals
Even one isolated fossil footprint carries real information: foot shape and toe arrangement can indicate whether the trackmaker walked on two legs or four, whether it was a meat-eater or plant-eater based on the general foot structure, and roughly how large the animal's foot was. Ichnologists even give some distinctive fossil track shapes their own names, separate from the species that made them, since the same foot shape sometimes can't be tied definitively to one known skeleton — Grallator and Eubrontes are two well-known examples of track types named this way.
Where it gets powerful: the trackway
A single print is useful, but a full trackway — a sequence of footprints from the same moving animal — is where the science becomes genuinely revealing. The distance between successive prints of the same foot (the stride length) and an estimate of the animal's hip height, usually inferred from the track's size and known body proportions of similar animals, feed directly into a speed-estimation formula developed by biomechanist R. McNeill Alexander in 1976. The same equation is the basis of the Stride Length Gait & Speed Calculator on this site — the same physics that estimates whether a modern coyote was walking or running from its trackway also estimates whether a theropod dinosaur was strolling or sprinting from its fossilized one.
Herds, not just individuals
Some of the most striking trackway sites preserve dozens of parallel trails moving in the same direction at once — strong evidence of herding or group behavior that bones alone could never demonstrate, since a bone bed just shows that animals died in the same place, not that they were moving together in life. Lark Quarry in Australia is a famous example interpreted by many researchers as evidence of a mass movement of smaller dinosaurs, though like much of paleontology, the exact interpretation of any single site is regularly revisited as new analysis methods and evidence emerge.
The same skill, a much longer timescale
What makes fossil trackways genuinely remarkable is how directly the reading skill transfers. The habit of examining stride length, straddle, and gait pattern that lets a tracker read a fresh coyote trail in the mud this morning is the same habit, applied with the same underlying math, that lets a paleontologist read a 200-million-year-old dinosaur trackway preserved in stone. Tracking, in that sense, is one of the few outdoor skills that connects directly to the deep history of life on Earth — the ground has been recording how animals move for a very, very long time.