Tyrannosaurus rex struck the ground toe-first, much like a modern bird, rather than plodding along on flat feet as scientists long assumed. A study published on Feb. 25, 2026, in Royal Society Open Science used biomechanical modeling of four well-preserved T. rex specimens to reach that conclusion, estimating that the tiptoe gait boosted the predator’s top speed by roughly 20%. The finding reshapes how paleontologists understand the movement, balance and hunting ability of the most famous carnivore in the fossil record.
Biomechanical Models Replace Old Assumptions
For decades, popular reconstructions depicted T. rex as a heavy, flat-footed animal whose sheer mass limited it to a lumbering walk. The new research directly challenges that image. Scientists applied quantitative biomechanical modeling to simulate alternative foot-strike patterns, comparing a flat-footed stance against a toe-first, or digitigrade, strike across four well-preserved T. rex individuals. The digitigrade model consistently outperformed the plantigrade one, producing a gait that better matched the skeletal anatomy of the lower limb and the stress distribution visible in fossilized trackways.
The toe-first model also changed estimates of how fast T. rex could move. According to simulations summarized by science reporters, the tiptoe configuration increased estimated top speed by about 20%, with results expressed in both meters per second and miles per hour. That difference matters for reconstructing predator-prey dynamics in the Late Cretaceous. A 20% speed gain turns a slow pursuit predator into something far more dangerous to contemporary herbivores like Triceratops and Edmontosaurus, animals that themselves relied on speed or bulk to survive.
Walking Like an Eight-Ton Bird
The comparison to birds is not just a colorful analogy. Modern birds are the direct descendants of theropod dinosaurs, and their feet share deep structural similarities with those of T. rex. Avian feet are defined by specialized bone fusions and specific digit configurations that enable springy, energy-efficient locomotion. The new study argues that T. rex used its feet in a functionally similar way, striking the ground with its toes and using the elastic properties of tendons and ligaments to absorb and return energy with each step. The New York Times described the animal as running on its tiptoes (“like an 8-ton chicken”), a phrase that captures the surprising kinship between the apex predator and its living relatives.
Tiptoe walking also changed how T. rex managed its enormous body weight. Humans, by contrast, tend to run with relatively stiff, spring-like legs that store energy in a different way. For a multi-ton theropod, a toe-first strike distributed ground-reaction forces more evenly across the foot, helping the animal stay balanced on uneven ground. That stability advantage would have been significant for an animal hunting across floodplains, riverbeds, and forested environments where flat, predictable ground was rare.
Fossil Trackways Confirm the Toe-First Strike
The biomechanical models did not exist in a vacuum. Researchers cross-checked their simulations against physical evidence preserved in stone. In some well-preserved tyrannosaur trackways, digits III and IV show greater depth than impressions left by the other toes, a pattern highlighted in the museum’s outreach materials on dinosaur locomotion. That distribution is exactly what a toe-first strike would produce. The central, weight-bearing digits press deeper into soft substrate because they absorb the initial impact. A flat-footed animal, by contrast, would leave a more uniform impression across the entire sole.
Separate research on early theropods and bird-line taxa has used foot structure and soft-tissue proxies to reconstruct locomotor ecology in related species. Those studies established that foot morphology varies with how an animal moves, whether it runs, perches, climbs, or wades. The T. rex findings fit neatly into that broader framework: the foot of a fast-moving, ground-dwelling predator should look and function differently from that of a tree-dwelling or aquatic species, and the trackway evidence supports that expectation by showing concentrated pressure under the main load-bearing toes.
What This Changes About T. rex
The practical upshot is that paleontologists now have a stronger basis for treating T. rex as an active, agile hunter rather than a slow scavenger. The scavenger hypothesis, which gained traction in the early 2000s partly because of doubts about T. rex’s speed, relied on the assumption that the animal was too heavy and too slow to chase down prey. A 20% speed increase, combined with evidence of stable, energy-efficient foot mechanics, weakens that argument considerably. It does not settle the debate on its own, but it removes one of the key physical objections to the predator model and aligns with healed bite marks and other signs of active predation seen on herbivore fossils.
The study also reinforces the evolutionary link between theropod hindlimb anatomy and the distinctive walks of modern birds. Scientists have long known that birds inherited their leg structure from dinosaurs, but the foot-strike function itself (the specific way the foot contacts the ground) has been harder to pin down. Recent work on hindlimb evolution in bird-line archosaurs shows how incremental changes in joint angles and tendon paths can transform posture and gait over millions of years. The toe-first T. rex helps bridge the remaining gap, suggesting that the springy, digitigrade stride of today’s birds was already well established in their giant Cretaceous cousins.
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*This article was researched with the help of AI, with human editors creating the final content.
