On the windswept, predator-free offshore islands of New Zealand, a creature of immense evolutionary significance walks the damp forest floor. To the untrained eye, the tuatara ( Sphenodon punctatus ) appears to be a typical lizard, perhaps resembling an iguana with its spiny crest and weathered, primeval skin. Yet, this reptile is one of the most profound anomalies in modern zoology. It is not a lizard at all, but rather the sole surviving member of Rhynchocephalia, an ancient order of reptiles that flourished during the Triassic period, some 250 million years ago. While the dinosaurs rose, dominated the planet, and vanished into the fossil record, the ancestors of the tuatara quietly persisted. Today, the species exists as a living window into the Mesozoic Era, preserving anatomical features that have been lost in all other living tetrapods. Its survival in the isolated archipelago of New Zealand has allowed scientists ...