'Ugliest Fossil Reptiles' From China were World Travelers, Study Finds

Long before dinosaurs reigned the Earth, hefty herbivores known as pareiasaurs dominated some 260 million years ago. Described as the "ugliest fossil reptiles," pareiasaurs had a tiny head with small teeth and stumpy limbs on barrel-shaped bodies covered in bony knobs. 

Pareiasaur fossils have been collected from South Africa, Europe -- Russia, Scotland, and Germany -- China, and South America. But even with a wide assortment of fossil specimens, researchers were still unsure whether there were distinct groups on each of these continents -- until now. 

In the latest study, paleontologists from the University of Bristol have for the first time closely examined all Chinese specimens of these creatures. Despite their unattractive appearance and lumbering gait, researchers believe the massive herbivores were able to travel the world.

"Up to now, six species of pareiasaurs had been described from China, mainly from Permian rocks along the banks of the Yellow River between Shaanxi and Shanxi provinces," Professor Mike Benton, of Bristol's School of Earth Sciences, said in a news release. "I was able to study all of these specimens in museums in Beijing, and then visit the original localities. It seems clear there were three species and these lived over a span of one to two million years."

Their analysis revealed close similarities between Chinese fossils and those found in Russia and South Africa, suggesting the animals were able to travel across the supercontinent Pangea. 

Pareiasaurs, measuring between two to three meters long from head to tail, likely lived in damp, lowland areas, feeding on huge amounts of vegetation. Fossils recovered from Russia also indicate pareiasaurs rolled around in the soft mud, perhaps to cool down or protect their skin from parasites.

The recent study confirms the three Chinese pareiasaur species differed from each other in body size and in the shapes of their teeth.

"My study of the evolution of pareiasaurs shows that the Chinese species are closely related to relatives from Russia and South Africa. Despite their size and probably slow-moving habits, they could walk all over the world," Bengon added in the university's release. "We see the same sequence of two or three forms worldwide, and there is no evidence that China, or any other region, was isolated at that time."

Researchers say pareiasaurs were the first truly large herbivores, but their tenure was fairly short. Having roamed the Earth for only 10 million years, the reptiles were wiped out during the end-Permian mass extinction 252 million years ago, when 90 percent of all living species were killed by acid rain and global warming caused by massive volcanic eruptions in Russia.

Their findings were recently published in the Zoological Journal of the Linnean Society. 

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