Lazy, Gluttonous Dinos Were Prehistoric 'Couch Potatoes'

Dinosaurs grew to their massive sizes because of lack of exercise and easy access to food, according to a leading zoologist. Dr. Brian McNab studied large mammals for comparison and concluded that a lack of energy expenditure, combined with abundant resources and a blood temperature somewhere between warm and cold, allowed herbivores to balloon to many times the size of equivalent mammals, the Daily Telegraph reports.

"Like couch potatoes sitting within easy reach of high calorie foods, the gargantuan size of dinosaurs most likely stems from the abundance of resources available, coupled with low energy expenditures," McNab said. (More dinosaurs stories.)