Mark PhilbrickWhy did the iguana go to Fiji and Tonga? Who knows? But a study by BYU biology professor Jack W. Sites Jr. published in the American Naturalist offers an answer to one of the most perplexing scenarios in island biogeography: how iguanas got there.

Biologists have long tried to explain how a certain species of iguanids found abundantly in the Americas have close relatives in Fiji and Tonga, 5,000 miles away. Sites suggests that—rather than rafting there on logs or debris, as a leading hypothesis theorizes—the reptile’s ancestors walked. His analysis of Fijian and Tongan iguana DNA revealed a lineage dating back more than 60 million years, when the land that would become these islands was part of a supercontinent.