Abstract .The tuatara ( Sphenodon punctatus )—the only living member of the reptilian order Rhynchocephalia (Sphenodontia), once widespread across Gondwana1 , 2—is an iconic species that is endemic to New Zealand2 , 3. A key link to the now-extinct stem reptiles (from which dinosaurs, modern reptiles, birds and mammals evolved), the tuatara provides key insights into the ancestral amniotes2 , 4. Here we analyse the genome of the tuatara, which—at approximately 5?...