In Pursuit of Early Mammals / В погоне за первыми млекопитающими

Since the demise of non-avian dinosaurs some 65 million years ago, modern mammals—that is to say, marsupials, placentals, and monotremes—have become conspicuous, diverse elements of Earth’s biota. But the family tree that includes mammals and their nearest relatives (mammaliaforms, in technical parlance) is far more deeply rooted in time, extending back to perhaps 220 million years ago. Clearly, then, the varieties known from the “age of mammals” that followed dinosaur extinctions represent only the uppermost boughs of what is increasingly being revealed as a bushy, complex tree. <...>