Woolly Rhinoceros

While other ancient animals seem trapped in evolutionary stasis, others were quietly in the process of revolutionary transformation. A brand-new study contends that most of the animals we now equate with cold—woolly mammoths, arctic foxes, musk oxen, lemmings—didn't suddenly develop to cope with ice age extremes. Rather, they arose step by step over millions of years, in waves tied to large climatic changes. A Stage-Wise Adaptability: Lost in Transition The research, published in Trends in Ecology and Evolution, finds two principal stages in the development of cold-adapted vertebrates. The initial, in the Late Pliocene to Early Pleistocene ( ‘Ice Age’) period (approximately 3 to 2 million years ago), witnessed the appearance of genera that would eventually yield tundra and boreal