In Jurassic Tanzania, Giraffatitan stood among the largest dinosaurs to ever walk the Earth. We know it for its sweeping neck and tree-top appetite. But little attention has been paid to the other end of its body: the tail.
That forgotten half—11 meters (35 feet) of vertebrae trailing behind the sauropod—is finally having its moment.
A new study, led by Verónica Díez Díaz of the Museum für Naturkunde in Berlin and published this month in Royal Society Open Science, offers the most detailed reconstruction to date of the range of motion in the tail of Giraffatitan brancai. What the team discovered overturns decades of assumptions and paints the sauropod’s tail as a dynamic, flexible organ capable of astonishing movement.
Decoding Dinosaur Tails, Vertebra by Vertebra
For nearly ten years, Díez Díaz has been assembling what amounts to a biomechanical jigsaw puzzle of Giraffatitan’s posterior. The fossil in question, catalogued as MB.R.2921, comprises 18 exquisitely preserved tail vertebrae and 14 chevron bones, or haemal arches, from a single animal excavated from the famed Tendaguru Formation.
“Although tails precede the evolution of paired appendages in vertebrates by approximately 200 million years, we are just starting to understand their function, development and evolution,” the study notes. And in the case of Giraffatitan, the team’s 3D modeling work has revealed that its tail wasn’t a stiff rod. It was a modular, muscular marvel that curled, flexed, twisted, and swayed in ways few had imagined.
Previous reconstructions often depicted sauropods dragging their tails behind them or holding them stiffly aloft like a beam. But Díez Díaz’s simulations show something quite different. The tail could arch upward to over 100 degrees, flex downwards more than 50 degrees, and swing side to side with substantial range. In some configurations, it could even twist in place.
“The main use of the tail was to propel the hindlimb, i.e., to move the animal,” Díez Díaz told IFLScience. “But they probably also used it as a tool for defence and communication with other animals.”
The Tail’s Role in Sauropods
The researchers used advanced digital tools to analyze the tail’s vertebrae in a series of simulations. Each bone was modeled in high resolution and digitally reassembled in what’s called the “osteological neutral pose.” This method restores the most natural alignment of bones, absent of taphonomic distortion (the damage caused by fossilization). Using this reconstruction, they tested the possible movements between vertebrae, rotating each one until it met a “hard stop”—a point at which bones would have collided or disarticulated in life.
Key to the work was the reconstruction of the intervertebral cartilage, which doesn’t fossilize. Based on data from modern-day crocodiles and birds—distant relatives of sauropods—the team inferred the presence of fibrocartilaginous discs similar to those found in human spines. This soft tissue, the study argues, would have allowed the tail to bend and twist with considerable flexibility, particularly in its base near the hips.
“Haemal arches are not static elements,” the authors wrote. “They move together with the caudal series.” In fact, when fixed in simulations, these bony structures—located beneath the vertebrae—acted as physical constraints to movement, especially downward bending. But when modeled as mobile units (as they likely were in life), the tail revealed even greater flexibility.
Why Does Tail Mobility Matter?
Understanding how Giraffatitan’s tail moved helps answer broader questions about sauropod biology and behavior.
First, it informs locomotion. The front portion of the tail served as the attachment site for key muscles that powered the hind legs.
Second, tail mobility impacts our models of dinosaur metabolism. How far a dinosaur could walk, how fast it could travel, and how it used energy all depend in part on how the tail contributed to propulsion and balance.
And finally, there’s communication and defense. The study hints at the possibility that tail flicks or whips could have served as signals to other dinosaurs, or as predator deterrents, perhaps not too different from how modern animals like dogs wag their tails. While that remains speculative, the biomechanical range makes it plausible.
“These simulations will also help us to better understand the metabolic needs of these dinosaurs and the distances travelled in their migrations,” Díez Díaz said.
Old Fossils, New Perspectives
In the study, the team notes something unexpected: the tail’s joints differ significantly from those of the neck or spine. Rather than the stable, interlocking concavo–convex joints found elsewhere, the tail vertebrae are amphicoelous—shallowly concave on both ends. This architecture required thick intervertebral discs to cushion movement, like shock absorbers in a massive biological suspension bridge.
Perhaps even more intriguing is the discovery of a previously undescribed feature: a “double surface” on the postzygapophyses (bony projections that help vertebrae articulate, good luck trying to say that out loud). This feature appears to increase dorsal flexibility, and the team suspects it exists in other sauropods but has simply gone unnoticed.
“It is one thing to see those bones isolated in museum collections,” Díez Díaz said, “and quite another to be able to create musculoskeletal reconstructions and perform simulations in which these reconstructions move and walk.”
What’s Next?
The study of MB.R.2921 is only the beginning. Díez Díaz and her colleagues are now expanding their biomechanical analyses to other sauropod tails from the Tendaguru beds. They aim to piece together how different species coexisted, interacted, and moved across the Late Jurassic landscape.
“For me, the most exciting thing is to ‘bring these fossil remains to life,’” she said.
That excitement is matched by a growing appreciation in the field for what tails can teach us. Just as neck biomechanics transformed our understanding of how sauropods fed, tail biomechanics may reshape how we think about their movement, social lives, and survival strategies.
“We are getting closer and closer to reality,” Díez Díaz said.
And perhaps this work lets us see the dinosaur in full—not only the neck that stretched upward, but also the tail that trailed behind, driving its movement with balance, strength, and fluidity.
