Family ties

This tiny reptile roamed with the dinosaurs — and could solve an evolutionary mystery

A 150-million-year-old reptile looked a lot like its living relative.



Meet the tuatara.

These reptiles, native to New Zealand, weigh only three pounds as adults and can live to over a hundred years old.

Tuataras are also known as living fossils, due to the fact that they have many of the same characteristics as their ancient reptilian ancestors.

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Their lineage goes so far back that the tuatara’s predecessors roamed with dinosaurs.

And paleontologists just discovered a new member of the reptile’s family tree.

R. Andrew Odum/Photodisc/Getty Images


Writing this week in the Journal of Systematic Paleontology, researchers describe a new species of rhynchocephalian, the group of reptiles that includes tuataras.


Tuataras are actually the only species of rhynchocephalian living today. But these creatures used to be a diverse and populous group 200 million years ago.

The new species, Opisthiamimus gregori, dates back 150 million years to the Jurassic period.

Matthew Carrano

Matthew Carrano

O. gregori would have been about six inches long — small enough to curl up in the palm of a human hand.

Its remains were discovered near an Allosaurus nest in northern Wyoming. Those huge, meat-eating dinosaurs would have been O. gregori’s neighbors.

Matthew Carano

The shape of O. gregori’s head and teeth reveal that it probably ate insects, including ones with tougher shells like beetles.

Tuataras have a similar diet, but they also go for larger animals like birds and lizards.

Matthew Carrano

O. gregori’s body shape, complete with four legs and a tail, makes it seem a whole lot like a miniature version of its modern-day relative.

And continued study of O. gregori’s remains could help researchers answer a big evolutionary question about its successors: Why aren’t there any living rhynchocephalians besides the tuatara?


Though they look like lizards, rhynchocephalians are a different group of reptiles entirely.

Researchers are still trying to understand why they aren’t plentiful like lizards.


The fossil record shows that rhynchocephalians started to disappear hundreds of millions of years ago.

Afterward, lizards became a more dominant group and diversified into the many species we now see all over Earth.


“These animals may have disappeared partly because of competition from lizards but perhaps also due to global shifts in climate and changing habitats.”

Matthew Carrano, study author, in a press release


For now, the story of the rhynchocephalians’ disappearance remains clouded in mystery.

But living fossils like the tuatara — and actual fossils like O. gregori — could help unravel the past.

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