Tiny Triassic Jaw Fossil Reveals Early Lizard Evolution Secrets

Two hundred and twenty-five million years ago, while the first dinosaurs were still finding their footing, a creature no larger than a small lizard left behind a jaw the size of a fingernail in what is now southern Brazil. That fragment, belonging to Cargninia enigmatica, has now been reexamined with modern imaging tools, and it speaks quietly but clearly to one of evolution's most consequential branchings — the moment before lizards and snakes became lizards and snakes. In placing this animal just outside the true lepidosaur lineage, scientists have located a rare waypoint in the long road th