The cow-size reptile is a pareiasaur, of a group of herbivores found across Pangea during the Middle and Late Permian, about 252 million to 266 million years ago.

Most pareiasaurs had bony knobs on their skulls, but Bunostegos’s are the most bulbous ever found. The researchers, who reported their findings in The Journal of Vertebrate Paleontology, believe the knobs resembled the skin-covered horns on the heads of modern giraffes.

Geological data suggests that the region was extremely dry.

“There was probably some sort of oasis these animals lived off,” Dr. Sidor said. “Flowing water was there, but it was probably ephemeral.” SINDYA N. BHANOO