National Geographic : 1956 Mar
Fossils Lift the Veil of Time 363 In These Telltale and Often Beautiful Relics of Vanished Ages, Science Reads Life's Story and Finds a Key to Mineral Treasure BY HARRY S. LADD AND ROLAND W. BROWN U. S. Geological Survey ASK the man in the street what a fossil is, and he'll say it has something to do with dinosaur bones. He's par tially right, of course, but there is more to fossils than that. Fossils are patterns in life's broad tapestry, significant relics of that long past which has made the present possible. As for dinosaur bones, you will see them dramatically mounted when you walk into the United States National Museum of the Smith sonian Institution in Washington, D. C. Up stairs, where our offices are, most of our study specimens obligingly squeeze into the shallow trays of cabinets that line the walls. One of us, Roland Brown, specializes in plants. Harry Ladd concentrates on spineless crea tures of the sea-mollusks, corals, and so on. That doesn't mean we don't collect other unusual and fascinating things. Finds Oldest Fossil Palm Fossils answer many questions about the world's dim past. For example, Brown tells of a recent find that extended our knowledge of flowering plants by fully 10 million years. It was September, 1953. I had just com pleted my summer field work out west, and on my way back to Washington I dropped in at the Denver office of the U. S. Geological Survey. Something was in the air. I could tell by the way Dr. G. Edward Lewis, verte brate paleontologist, greeted me. "Brownie, I've got something to show you!" he exclaimed. Lewis, tall and wiry, was ob viously excited. "What's it all about, Ed?" I asked. "Got a new dinosaur by the tail?" I knew that he had been exploring deposits from the Tri assic period in southwestern Colorado. These red sandstones, laid down by streams in ages past, were known to contain fossil reptile teeth. Lewis had been hunting skeletal re mains of the original owners. My friend only grinned and waved me to follow. In his office, fossils not yet classified cluttered a table. He selected a rock sample and ripped off its burlap cover. "Take a look at this," he said. A large, fragmentary leaf imprint showed on the red sandstone slab. None of the origi nal substance remained. Except for the broken edges, however, the details were so perfect that the mold might have been made in colored plastic or concrete the night before. The ribbed structure was unmistakable. "Ed, you've got a palm," I said. "How can that be? It's from the Triassic, and no one's ever found a palm dating back that far!" Tip and stem were gone, but I could see the resemblance to leaves that appear first on the seedlings of all living palms. Yes, this was a palm, or its immediate progenitor. An important find, bearing on the origin of modern plants. "Do you have any more like it?" I asked. "This is all I've come across," he said. The next summer I returned to Denver to continue the search. Lewis and I jeeped back into the rugged, semiarid terrain around Placerville, Colorado. Here the San Miguel River cuts the painted west slope of the San Juan Mountains. Birches, willows, and cot tonwoods line the stream banks. Pifion and spruce forest the higher reaches. Lewis and I pushed through clumps of juniper, skunkbush, and scrub oak. We clambered up steep, crumbling slopes to where rock outcrops punch red holes in the canyon's scraggly green cloak. What a story these rocks had to tell! When Dinosaurs Were Young When the red beds were formed, some 165 million years ago, no mountains thrust jagged crests skyward where the San Juans now stand. There was only a featureless plain. Stubby-tailed amphibians peered out from sluggish streams; crocodilelike phytosaurs crawled among ferns and rushes. Dinosaurs - a s yet small and slender, not the terrible beasts they were to become-ran two-legged across the monotonous landscape. Only the most primitive mammal progenitors trod the earth. No dragon soared on leathery wings; no feathered bird had seen the light of day.