How Smaller Dinosaurs Avoided Becoming a Meal

With so many colossal dinosaurs roaming around the planet millions of years ago, it's a wonder the smaller guys managed to survive at all. But new research shows that the large plant-eating dinosaurs developed a number of useful tactics to avoid becoming a meal.

Researchers describe in the Indiana University Press compendium "Hadrosaurs" how many herbivores outwitted, outfought and outlasted the big carnivores. Biting, kicking, tail whacks and running away are just some of the maneuvers they used.

"There are very few large animals that, when attacked, cannot defend themselves by kicking, biting or lashing out with whatever kind of appendages they've got," co-author Scott Persons told Discovery News.

That can possibly explain why researchers find so many more fossils of hadrosaurs - also known as duck-billed dinosaurs - and other plant eaters than big carnivores like the Tyrannosaurus rex.

To better understand interactions between carnivores and herbivores, Persons and his co-author, paleontologist Phil Currie from the University of Alberta, re-created life or death chases between these dinosaurs.

According to the study, plant-eating dinosaurs evolved impressive horns or spiked armor to turn themselves into walking fortresses, or lightweight bodies and extra-long legs to help them outrun predators.

What's more, hadrosaurs had a very keen sense of smell allowing them to sniff out T. rex and others, and also traveled in large packs to better protect themselves.

But mostly running away, thanks to their strong caudofemoralis muscle in their tails, proved to be the most successful tactic.

"Imagine we go to the Dino Derby," Persons told Discovery News. "In a race between a tyrannosaur and a hadrosaur, it used to be that the smart money was all on the tyrannosaur. Well, bang! The race begins and, sure enough, with longer legs the tyrannosaur bursts out of the starting gate and into an early lead."

However, if it got a running start, the hadrosaur's impressive musculature would have given it greater endurance, allowing it to outrun the tyrannosaur.

So they might not be the most ferocious of dinosaurs, but plant eaters were certainly faster, which helped, giving scientists a glimpse into life on Earth with carnivores and herbivores alike running around.