London: Paleontologists have argued that dinosaurs' size was in some way due to the way they regulated the temperature of their blood.
But, a team, led by leading zoologist Dr Brian McNab at Florida University, has claimed that the dinosaurs grew to such a big size as they actually the "couch potatoes" of the prehistoric world.
According to Dr Brian McNab, having easy access to food, coupled with their sedentary lifestyle when not hunting, helped the creatures grow into the biggest beasts to have ever walked the earth.
"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. Some dinosaurs reached masses that were at least eight times those of the largest, ecologically equivalent terrestrial mammals.
"The factors most responsible for setting the maximal body size of vertebrates are resource quality and quantity, as modified by the mobility of the consumer, and the vertebrate's rate of energy expenditure," he was quoted by leading British newspaper The Daily Telegraph as saying.
In fact, the team has claimed that the availability of food resources was more important. Using a model based on a vertebrate's energy expenditure, mass and eating habits, it explained the body size of existing as well as extinct mammals including whales, ancient rhinoceros and modern elephants.
The team used the example of the larger mass found in some marine mammals which reflect greater resources in their environment.
While Dr McNab said that thermal biology differences were easily seen in small organisms, he suggested dinosaurs were neither cold nor warm blooded but they had maintained an intermediate temperature between mammals and reptiles, thanks to their size.
Some dinosaurs ate lizards, turtles or eggs, while others hunted other dinosaurs. The majority ate plants.
Many of these plants, which can be seen in fossils, had edible leaves, including evergreen conifers such as pine trees, redwoods and their relatives, ferns, mosses and in the latter stages of the dinosaur age, flowering fruit plants.
The findings are published in the Proceedings of the National Academy of Sciences journal.