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A newly published analysis of the bones of Bunostegos akokanensis, a 260-million-year-old pre-reptile, finds that it likely stood upright on all fours like a cow or a hippo, making it the earliest known creature to do so. To date, all of the known pareiasaurs who roved the supercontinent of Pangea in the Permian era a quarter of a billion years ago were sprawlers whose limbs would jut out from the side of the body and then continue out or slant down from the elbow like some modern lizards.
Researchers expected Bunostegos would be a sprawler, too, but the bones of the animal’s forelimbs tell a different story.Image credit: Drawings by Morgan Turner
