If you visited Wyoming around 50 million years ago, you might see a peculiar little bird racing through the hot, dense forests of the Eocene. About the size of a chicken, the creature would look something like a modern-day tinamou. In fact, that connection is pretty close to the mark. In a recent paper by Jackson School of Geosciences paleontologists, the prehistoric bird is revealed to be related to the flightless family that now holds ostriches, emus, and their kin. The newly described species is Calciavis grandei, or “Grande’s stone bird” (named in honor of paleontologist Lance Grande). Researchers Sterling Nesbitt and Julia Clarke found several of its skeletons in the quarries of Wyoming—famous for their abundance of fossil fish and other exquisitely preserved specimens—including one with feathers, foot scales, and claw sheaths still intact. This is the kind of fossil that paleontologists dream of collecting. How does the species fit into the broader avian...