Get the Popular Science daily newsletter💡 Breakthroughs, discoveries, and DIY tips sent six days a week. The Archaeopteryx is one of evolution’s most infamous species—but it’s also a very confusing creature. All present-day birds are technically dinosaurs, but the 150-million-year-old, raven-sized hunter is the earliest known example of an avian animal. At the same time, Archaeopteryx lived during the Jurassic Period among multiple other feathered dinosaurs that were not birds in the true sense of the term. But if it’s any consolation, it’s often still difficult for paleontologists to tell them apart, too. “For a long time, there have been very few things that we could say really characterize the transition from terrestrial dinosaurs to flying bird dinosaurs,” explained Jingmai O’Connor, the associate curator of fossil reptiles at Chicago’s Field Museum. O’Connor and her team spent over a year carefully preparing and examining the museum’s own Archaeopteryx specimen after its arrival in 2022. In a study published on February 2nd in the journal The Innovation, the team described a set of newly analyzed anatomical features …