A distant cousin of the tuatara also survived the extinction event that killed the dinosaurs, only to become extinct later, a new study has found.

Rhynchocephalian lepidosaurs were once widespread across the world, but are today represented only by the tuatara, or Sphenodon.

A paper published in the journal Proceedings of Royal Society B, published today, has shown our tuatara wasn't the only species of its kind to survive the catastrophic impact of an asteroid during the K/Pg extinction event 66 million years ago.

Fossil evidence of a small reptile, named K. peligrensis, suggests it survived it South America beyond the extinction event, but became extinct a few million years later.


The study, led by Professor Sebastian Apesteguia of Maimonides University in Buenos Aires, Argentina, described the species as "markedly smaller" than many of its close relatives.

Northern tuatara adult males can measure 61 cm and weigh up to 1kg.

Susan Keall, a senior technical officer in Victoria's School of Biological Sciences, was not surprised to hear of the study finding.

"We knew fossils of [tuatara's] ancestors have been found in other countries around the world, and definitely, they were more widespread at that time than they are today." The tuatara is commonly referred to as New Zealand's "only living dinosaur", but more recently, scientists had decided not to use this term, she said.

"This is because it suggests it was a dinosaur, but actually, the ancestors of tuatara in that lineage were living at the same time as the dinosaurs," she said.

"Reptiles that existed during the dinosaur era included many species of dinosaur, as well as the ancestors of tuatara."