Published on October 15th, 2015 | by Liz Martin-Silverstone


Episode 53: Ankylosaurs

Ankylosaurs are a group of non-avian dinosaurs best known for their armour, tank-like bodies, and sometimes large tail clubs. First appearing in the Jurassic, they were common in Late Cretaceous ecosystems, with several species known from around the world. But how different were these species really? And just where did they evolve from? What was that tail for?

Dr. Victoria Arbour of the North Carolina Museum of Natural Sciences is one of the leading experts on ankylosaurs, and has published a number of papers, including a recent study on how the tail club evolved. We spoke with Victoria about these dinosaurs and she answered some of these questions for us.

Ziapelta reconstruction by Sydney Mohr

Ankylosaurine ankylosaurids, like Ziapelta from New Mexico, had tails modified into axe­like weapons that we call tail clubs. (Sydney Mohr)

pinacosaurus at IVPP

This is a juvenile specimen of Pinacosaurus (with Victoria’s head for scale), found in a cluster of other juveniles during the Canada­China Dinosaur Project in the late 1980s.

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Two tail club knobs at the Royal Ontario Museum. Victoria is holding the smallest known club, and standing next to one of the biggest.


Three hypotheses for how tail clubs may have evolved. (Victoria Arbour)

Dyoplosaurus tail club and Gobisaurus handle

Top: the tail club of Dyoplosaurus has modified vertebrae and large osteoderms. Bottom: Gobisaurus has modified vertebrae like those of Dyoplosaurus, but no large osteoderms. (Victoria Arbour)


Gobisaurus would have had a stiff tail, but probably did not have a large knob of bone at the tip. (Sydney Mohr)

Liaoningosaurus handle

Liaoningosaurus is the earliest example of an ankylosaur with tail vertebrae with long, robust prezygapophyses. (Victoria Arbour)


Timeline of ankylosaur tail evolution. (Victoria Arbour)

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