From Ancient Origins
How and when did dinosaurs first emerge and spread across the planet more than 200 million years ago? That question has for decades been a source of debate among paleontologists faced with fragmented fossil records. The mainstream view has held that the reptiles emerged on the southern portion of the ancient supercontinent Pangea, called Gondwana, millions of years before spreading to the northern half, named Laurasia.
But now, a newly described dinosaur whose fossils were uncovered by University of Wisconsin–Madison paleontologists is challenging that narrative, with evidence that the reptiles were present in the northern hemisphere millions of years earlier than previously known.