Over 250 million years ago, just before the first known dinosaurs emerged, the bumpy-faced beast Bunostegos dominated the world's one big desert.
The reptile struck quite a pose on the dry central Pangea landscape. (Pangea, aka "All Earth," was the enormous supercontinent that existed before the land mass broke up into parts.) The beast's territory is now northern Niger.
"Imagine a cow-sized, plant-eating reptile with a knobby skull and bony armor down its back," Linda Tsuji of the University of Washington, who led the research, was quoted as saying in a press release.
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The aptly-named genus Bunostegos means "knobby roof."
This distinctive prehistoric animal was a pareiasaur, meaning a large, plant-loving reptile common across Pangea. Most of these beasts had bony knobs on their skulls, but Bunostegos sported the largest and most bulbous ones ever discovered. These knobs were like the skin-covered horns (technically called ossicones) seen today on modern giraffes, or at least that's the present theory.
In giraffes, these bumps help to distinguish males from females, since only females have obvious tufts of fur on theirs. They also help to protect the heads of males during combat, which is one reason why the bumps are usually hairless on males. Over time, the hair and skin on them wears away. Perhaps the bumps held similar functions in pareiasaurs.
Since Bunostegos had characteristics of even earlier reptiles, the researchers think a population of these cow-sized reptiles persisted in the supercontinent, essentially isolated, for millions of years.
"Our work supports the theory that central Pangea was climatically isolated, allowing a unique relict fauna to persist into the late Permian," said co-author Christian Sidor, also from the University of Washington.
This is surprising, he said, because areas outside the central Pangea region show fossil evidence of regular faunal interchange back in pre-dino times.
Paleontologist Gabe Bever, who was not involved with the study, said, "Research in these lesser-known basins is critically important for meaningful interpretation of the Permian fossil record. Our understanding of the Permian and the mass extinction that ended it depends on discovery of more fossils like the beautifully bizarre Bunostegos."
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We pay a lot of attention to the mass extinction that killed off all of the dinosaurs, but Bever is referring to the extinction that paved the way for the earliest dinosaurs to dominate the planet in the first place.
As Bunostegos proves, impressively big beasts were around long before T. rex and other dinosaurs emerged. They look to have been very tough species, able to survive in what sounded like a not very hospitable environment.
Illustration by Marc Boulay