Sapeornis Chaoyangensis

Photograph by O. Louis Mazzatenta

This Sapeornis chaoyangensis fossil, housed in a Beijing museum, offers clues about the feeding habits of the Earth's early birds. The presence of gastroliths—stones ingested by animals to grind food in the gut—indicates that this species was a plant-eater. Other significant features include exceptionally long forelimbs, suggesting that Sapeornis, the largest known bird from the early Cretaceous, might have been able to soar.