Why animals don't have the weaponized tails seen in prehistoric times

Researchers look at the evolution of animals to learn why they no longer have weaponized tails 

Why animals don't have the weaponized tails seen in prehistoric times 
February 15, 2018

Some dinosaurs used their tails as weapons 

If you think the dinosaur pictured above looks a bit like a prehistoric, living army tank, you’re not alone. Often compared to a tank, this dinosaur is an ankylosaurus.

These creatures boast a rock-hard, spike-covered hide that is also rimmed with spikes.

Perhaps even more formidable and frightening, it carries a huge bone-crushing clubbed tail. Apparently, tail weapons were in fashion back then.

Stegosaurus also kept enemies at bay with a spike-covered tail. And several other dinosaurs sported various types of tails with clumps of embedded bone that could be whipped around at potential predators.

Evolving away from tail weapons  

This past trend had Dr. Lindsay Zanno wondering: where is the fearsome tail weaponry in animals today? Zanno is a paleontologist at North Carolina State University and the Division Head of Paleontology at the North Carolina Museum of Natural Sciences. She says it takes a lot to evolve a weapon-covered tail. According to Zanno, those tail weapons are out of fashion today because they just aren’t needed anymore.

In a research paper published in the Proceedings of the Royal Society B, Zanno and her colleague Victoria Arbour, a paleontologist at the University of Toronto and the Royal Ontario Museum, found only huge, slow vegetarians with body armor developed weaponized tails. The researchers compiled a list of 300 extinct and living species of mammals, reptiles, birds and dinosaurs and studied their characteristics.

Zanno believes that back in the dinosaur age, tail weapons were used for self-defense against predators or to compete within their own species over resources, territory or mating.

“Animals that live in water or trees need flexible skeletons while those that hunt may need more speed or better sensory capabilities,” says Zanno. “Animals that are smaller can hide from predators.”

So it only made sense for creatures that are slow, large and obvious to have a weaponized tail. Which is why the researchers found there aren’t any living creatures with tails like that today. Instead, evolution favored creatures that developed horns or shells. That is today's fashion: armor on the body or head, not the tail—think a goat, deer, moose or turtle.

—Frank Graff 

Frank Graff is a producer/reporter with UNC-TV, focusing on Sci Tech Now North Carolina, a weekly science series that airs Tuesdays on UNC-TV. In addition to producing these special segments, Frank will provide additional information related to his stories through this North Carolina Science Now Reporter's Blog!