CBC Radio’s Quirks & Quarks has a segment about dinosaurs that fought with their tails.  There were quite a few dinosaurs that evolved defence mechanisms centered around their tails.  Examples are Stegosaurs, Ankylosaurs, and maybe some Sauropods.  Modern animals with powerful weapons, overwhelmingly use their heads instead of their tails, think rams, deer, elk, with large horns.  A paper, by Victoria Arbour and Lindsay Zammo in the Proceedings of the Royal Society B, speaks to why this has changed.

To use your tail as an effective weapon, you likely have to be a large, armoured herbivore. That’s the conclusion of a new study by Canadian researchers.

Today when we see animals with powerful weapons, they are often found on the head. Think of rams smashing together their massive, coiled horns, or the crocodile’s powerful jaws and teeth or a hawk’s sharp beak.

Nowadays, the list of animals that pack their weapons in the posterior is much shorter. But it wasn’t always that way. Large, armoured dinosaurs like Stegosaurus and other prehistoric animals used to maim and kill with their tails.

This week, researchers in Ontario and North Carolina published a study looking into why weaponized tails became such a rare sight in the modern animal kingdom.