Making of North America Part 3 1. in an Empty Corner of Utah Lies a Very
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Making of North America Part 3 1. In an empty corner of Utah lies a very special place. It is a remote region called the Kaiparowits Plateau. This area contains an important story of the history of life in North America. Professor Kirk Johnson is with paleontologist Joe Sertich. This area is jam packed with __________________ fossils. A trick of Professor Johnson to tell if a rock is a piece of fossil bone is to see if it sticks to his ___________________. They have with them the cast of the skull of a dinosaur that Joe helped identify and name. From the teeth you can easily tell it is a ________________ eater. This dinosaur is called Lythronax which means the “king of ______________.” Lythronax looks a look like the more famous Tyrannosaurus ____________, but it is 10 million years older. 80 million years ago, all of North America was home to such creatures of as Lythronax. More than a __________________ of all the dinosaurs fossils ever found have been found in North America. 2. Before life was found on land, it existed in the sea as far back as 3.5 billion years. A connection to this early life is found in the Bahamas. Professor Johnson is there to see a rare living fossil. They are looking for one of the oldest organisms on the planet. After diving down 20 feet, they find the organisms they came to see; and it is the __________________. These are called stromatolites, and they are alive. A thin layer of ________________ (actually cyanobacteria) forms a somewhat sticky mat where mud and sand collects until a mound is built up. Today living and growing stromatolites are extremely _______________. In the Bahamas, these living mounds are often covered completely with sand by the strong currents, and later the currents will uncover them. This keeps plants and corals from growing on them and such things as snails from feeding on them. They didn’t have competition and predators billions of years ago. They were one of the dominant organisms in Pre-Cambrian seas for maybe _________ percent of Earth’s biologic history. They are the earliest fossilized form of life we have found. 3. During the early Pre-Cambrian, Earth’s atmosphere was very different than today. Most organisms today would suffocate under these early atmospheric conditions. However the cyanobacteria of the stromatolites could thrive under those atmospheric and oceanic conditions, and these bacteria developed a biological chemical reaction that used carbon dioxide and water and released ___________________. This reaction is called photosynthesis. Over the course of __________ years, stromatolites pumped out so much oxygen that the atmosphere changed into one that could support modern types of organisms. Modern organisms developed biological chemical reactions that can use (or consume) oxygen. It is thought from the rock record that about _______________ million years ago complex oxygen consuming life forms really took off. One such form of life, considered a primitive animal, were the _______________________. Later came the jellyfish types known as Cnidaria. These had nerves and muscles. Finally about ________________ million years ago dinosaurs appeared. 4. But what was it that allowed so many different types of dinosaurs to thrive here in North America. One clue can be found in the center of U.S. on the Great _________________ of central North America. Professor Johnson next takes us to Monument Rocks in ___________________. These rocks are made of chalk. Professor Johnson says that just 1 inch of this chalk represents _____________ years of deposition. This land is full of amazing fossils. Two people, Chuck Bonner and Barbara Shelton, have spent years finding and studying the fossils here. They showed Professor Johnson an 80 million-year-old marine fish named Xiphactinus which was ___________ feet long. About 130 million years ago much of North America was covered by a great inland sea. The coastlines around this inland sea produced a variety of habitats for dinosaurs. But 70 million years ago something dramatic began to happen; the inland sea began to _______________ away. 5. To explain what happened to this great sea, Professor Johnson next heads for Colorado. High up in the Rocky Mountains he finds what locals call “bird baths.” But they are actually the fossil of ancient _______________________ known as ammonites. This animal had a spiral, chambered shell with a fleshy head and tentacles at the open end. Its body plan was something like a ________________ or octopus to which it was related. The location of these fossils is west of Denver and over 7,700 feet above sea level. This elevation of the fossils is a consequence of plate tectonics. As this region rose the sea drained away leaving sea creatures high and dry. This was a very slow process as it is today. However not all biologic change happens slowly. To help us understand this, Professor Johnson is headed north to North Dakota and its __________-lands. 6. The rock here is known as the Hell Creek Formation which is a 300 foot-thick layer of rock that stretches over ______________ states. Much of the rock here is soft with charcoal from ancient fires. Professor Johnson is searching for a particular layer that is ______________ million years old. This important, ancient layer is a little rusty-orange sediment zone. This rusty colored zone may not look like much, but represents an Armageddon. The layer contains little round balls about a millimeter in diameter. These balls used to be ______________ beads. What could cause the formation of these glass beads? Something must have melted rock and tossed the melted globs up through the air to rain down on the landscape as glass beads. Perhaps the cause was a volcanic eruption. But the answer must be different because of what else is in this layer, tiny crystals of _________________ quartz. 66 million years ago and asteroid (some think comet) the size of _________ ________________ hit Earth with the power of a billion atomic bombs. Above the layer with those glass bead and shocked quartz there are no ___________________ fossils, only crocodile, turtle and bird fossils. This was an ecosystem-wide extinction event, with losses of half the species of plants and _____________________. One group that managed to hang on was the mammals, most of which at this time were small burrowing animals..