Stegosaurs were plant eaters, but they were far from the passive victims of predatory dinosaurs. Scientists have recently uncovered fossil evidence of one allosaur who got too close to a stegosaur’s unusually flexible spiked tail and didn’t live to regret it. At least not long.

The scientists say the stegosaur’s tail made a tell-tale conical wound near the allosaur’s pubis bone, causing an infection that probably killed the predator.

“A massive infection ate away a baseball-sized sector of the bone,” said Houston Museum of Natural Science paleontologist Robert Bakker.  “Probably this infection spread upwards into the soft tissue attached here, the thigh muscles and adjacent intestines and reproductive organs.”

The wound is similar to the type of goring wound large herbivores such as longhorn cattle inflict today, although of course coming from the other end of the animal.

Stegpsaur Kills Allosaur

Scientists think the stegosaur had a tail that was unusually agile  for a dinosaur.

“They have no locking joints, even in the tail,” Bakker explained.

“Most dinosaur tails get stiffer towards the end,” he said, but stegosaurs were an exception with big muscles at the base of their tails and flexibility and fine muscle control all the way to the end.

That would have been necessary to deliver the deadly blow to the allosaur, because the spikes on the tail normally point out and backward. The stegosaur would have had to sweep its tail under the allosaur and twist the tail tip.

“The joints of a stegosaur tail look like a monkey’s tail. They were built for 3-dimensional combat,” Bakker said.

[Source: Geological Society of America]

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