Archives of The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 29, Number 4;   April, 2002

Digest Quickly, Eat More

by Richard Stenger, CNN

The first land vertebrates that ate plants took up residence on terra firma about 290 million years ago, equipped with rudimentary jaws that allowed the reptiles to rip and tear leaves and stems, which they swallowed whole. But Suminia, a mammalian-like reptile that arrived on the scene 30 million years later, had the complex dental work necessary to chew its food in an efficient manner.

"The real boost in the success of vertebrates on land started with the ability to process plant food efficiently," said paleontologist Robert Reisz, one of the authors of the report, which will be published in the June 7 issue of the journal Nature. Suminia enjoyed distinct health advantages by chewing its food completely, a notion that human mothers today still try to impress upon their young. By breaking down the food into small bits before swallowing, the foot-long reptile was able to absorb much more plant energy and nutrients, the scientists said. The results transformed terrestrial Earth in the Paleozoic era.

"There is a link between the time when land-dwelling herbivores started processing food in the mouth and a great increase in animal diversity," said Reisz, a professor at the University of Toronto in Mississauga, Ontario. The mouthy milestone meant Suminia, its kin and descendents could digest more quickly and take in more food. Such increased intake could have supported an elevated metabolism, such as that necessary for warm-blooded animals, said co-author Natalia Rybczynski.

In 1990, Rybczynski and Reisz were part of a team that discovered Suminia fossils in a rugged region of central Russia called Kotelnich. Later plant-eaters developed similar eating equipment, including herbivorous dinosaurs, which made their earthly debut about 50 million years after Suminia.

Other animals that followed in the tooth steps of Suminia include many mammal herbivores, modern varieties of which can thank their ancient predecessor for having to run around so much. "You can say that the evolution of the modern terrestrial ecosystems with lots of herbivores supporting a few top predators is based on animals efficiently eating the greenery on the land," Reisz said.