Washington: A very distinctive creature known as a pareiasaur roamed the desert in what is now northern Niger during the Permian era.
Pareiasaurs were large, herbivorous reptiles that were common across Pangea (single supercontinent) during the Middle and Late Permian, about 266-252 million years ago.
"Imagine a cow-sized, plant-eating reptile with a knobby skull and bony armor down its back," lead author Linda Tsuji said.
The newly discovered fossils belong to the aptly-named genus Bunostegos, which means "knobby [skull] roof."
Most pareiasaurs had bony knobs on their skulls, but Bunostegos sported the largest, most bulbous ones ever discovered.
In life, these were probably skin-covered horns like those on the heads of modern giraffes.
Although at first blush these features seem to suggest that Bunostegos was an evolutionarily advanced pareiasaur, it also had many primitive characteristics.
Tsuji`s analysis showed that Bunostegos was actually more closely related to older and more primitive pareiasaurs, leading to two conclusions: first, that its knobby noggin was the result of convergent evolution, and second, that its genealogical lineage had been isolated for millions of years.
The study is published in the Journal of Vertebrate Paleontology.