190-million-year-old tuatara ancestor discovered

(ORDO NEWS) — Tuataria is a genus of primitive reptiles that includes the only modern species, Sphenodon punctatus. It lives exclusively on small islands near New Zealand.

Little is known about the evolutionary past of the tuatara, but now paleontologists have discovered its oldest relative, Navajosphenodon sani, which lived in Arizona 190 million years ago.

Modern tuatara (in Latin Sphenodon ) are represented by the only species that is distinguished as a special order of beak-headed reptiles.

These animals live only on a few small islands near New Zealand. At the same time, the pedigree of these reptiles is one of the most ancient and at the same time poorly studied. The fact is that the paleontological record has preserved only individual ancestors of the tuatara.

It is believed that with their closest relatives – the so-called scaly reptiles, lizards and snakes – the ancestors of the hatteria diverged 259 million years ago, at the end of the Permian period.

It is curious that beakheads were very widespread in the Triassic period – this is evidenced by finds in the territory of modern Great Britain, the USA, Germany, Brazil, Argentina and even Zimbabwe.

It turns out that at the beginning of the Mesozoic, the ancestors of the hatteria quickly settled throughout the northern part of the ancient supercontinent Pangea. Then they were more diverse than scaly reptiles. The beakheads lost their dominance to other reptiles only in the Cretaceous.

On the modern Earth, the flowering of the scaly reptile order, which has more than 11 thousand species, continues.

Among them are various snakes, lizards, monitor lizards, iguanas and so on. At the same time, the tuatara is the only modern species of beakheads. Recall that in addition to the beak-headed and scaly, the class of reptiles includes two more modern orders – crocodiles and turtles.

“The discovery of a near-complete North American beak-headed reptile was a landmark moment for paleontology,” said Dr. Nic Rawlence of the University of Otago, New Zealand.

The newly discovered relative of the tuatara Navajosphenodon sani lived about 190 million years ago, during the early Jurassic period. A new species was identified when studying the remains of 15 animals – for the most part these are fragments of teeth and jaws, but one of them was preserved almost entirely.

“With the help of amazing analytical methods, we were able to show that Navajosphenodon sani is the oldest known member of the modern tuatara lineage,” says the scientist.

“By comparing the new specimens with modern tuatara, we have shown that the structure of these reptiles has changed very little over the past 190 million years – this is a great example of the principle of “don’t fix what works”.

Dr. Rawlens also argues that this discovery is in good agreement with the slow evolution of the tuatara genome established by bioinformaticians.


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