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Kentrosaurus readies itself for an attack by an Allosaurus. Restoration by David Maas.

Kentrosaurus was a dinosaur you wouldn’t want to mess with. This smaller cousin of Stegosaurus, found in the Late Jurassic deposits of Tanzania, was armed with a formidable array of paired spikes along its tail. (And, in one of my favorite bits of fossil terminology, the spiked tails of stegosaurs are known as “thagomizers.”) Get hit with a tail like that and you’d be turned into an instant shish kebab. But just how much damage was the tail of Kentrosaurus capable of inflicting?

Late last year paleontologist Heinrich Mallison presented a revised look at the mechanics of Kentrosaurus. Among other findings, Mallison reported that Kentrosaurus was a fairly flexible dinosaur. When under attack, for example, Kentrosaurus may have thrown its head back to keep an attacker in its sights, and this armored dinosaur may have also bowed its forelimbs to better support itself while swinging its tail about. Now, in a follow-up to last year’s paper, Mallison has published the results of an investigation into how flexible and powerful Kentrosaurus‘ spiked tail itself may have been.

To experiment with Kentrosaurus, Mallison created virtual models of the dinosaur’s skeleton. This provided the framework on which muscles could be reconstructed and the forces generated by the tail could be estimated. Of particular importance was Mallison’s reconstruction of the dinosaur’s tail muscles. Rather than give Kentrosaurus a thin tail typical of many dinosaur illustrations, Mallison reconstructed the creature with a deep, thick tail that would have generated more power but would have also been quite heavy.

As it turns out, Kentrosaurus was a heavy hitter. According to Mallison’s models, the spikes at the tip of the dinosaur’s tail could have hit their target at a top speed of over 40 meters per second, and Kentrosaurus could have swung its tail at a speed in excess of 10 meters per second in a 75 degree arc. “At this speed,” Mallison writes, “the spikes could penetrate deeply into soft tissues or between ribs and were able to shatter bones.” He adds: “Penetrating impacts at 10 m/s created forces greater than those sufficient to fracture a human skull.” Ouch.

For more on Kentrosaurus defense, check out Mallison’s own post on the subject at the Palaeontologia Electronica blog.

References:

Mallison, H. (2011). Defense capabilities of Kentrosaurus aethiopicus Hennig, 1915 Palaeontogia Electronica