The distribution of different groups of organisms over the planet is rife with puzzles and contradictions. One of these longstanding head-scratchers concerns the major group of lizards called iguanians. There’s a major split among these reptiles. Forms with teeth fused at the top of their jaws – called acrodonts – are scattered throughout the Old World, but their closest relatives dominate the Americas, Madagascar, and a smattering of Pacific Islands. If lizards such anoles and agamas are close relatives, in other words, why are they so far away from each other?

Tens of millions of years before Gueragama, while the continents were still knit together to make the supercontinent Pangaea, the acrodont and non-acrodont lizards diverged from their common ancestor. The