California magazine

If paleontologists had a treasure map, "Here be fossils" would be written prominently over the Hayden Quarry in northern New Mexico. And now, for the first time, Berkeley researchers have unearthed evidence there that dinosaurs, their closest kin, and their "nondinosaurian relatives" coexisted for at least 15-20 million years. News of these bones' discovery appears July 19 in the journal Science.

The find shatters the long-held belief that the dinosaurs' predecessors all died before the dinosaurs started on their campaign to rule the earth—which they did for 140 million years. "That's the first time this has been found anywhere in the world," said UC Museum of Paleontology graduate student Randall Irmis, lead author of the journal paper. As the cherry on top, these fossils—including those of a newly discovered predecessor they've named Dromoremon romeri—were found in a rock formation younger than any in which "dinosaur precursors" had previously been found.

Reclusive painter Georgia O'Keeffe once referred to Ghost Ranch, where Hayden Quarry is located, as the place where "clocks stopped long ago." The Quarry's 220 million-year-old collection of fossils bears her out. Irmis, asked for an explanation of why these animals coexisted for so long, says all theories went out the window with their findings. "It's not really clear why the slow changeover occurred from precursors to the dinosaurs, but it's clear that it's really complex."

The rise of the dinosaurs, Irmis added, is a great example of evolution in action. "Every successful organism impacts their environment and humans do it, too." He sees parallels between the dinosaurs' story and humanity's own rise to dominant-species status. With that in mind, he says that the relatives of our replacements are already out there. And no, he doesn't think they'll be cockroaches.