This captivating book, laced with evocative anecdotes from the field, gives the first holistic, up-to-date overview of dinosaurs and their world for a wide audience of readers. Situating these fascinating animals in a broad ecological and evolutionary context, leading dinosaur expert Scott D. Sampson fills us in on the exhilarating discoveries of the past twenty-five years, the most active period in the history of dinosaur paleontology, during which more "new" species were named than in all prior history. With these discoveries--and the most recent controversies--in mind, Sampson reconstructs the odyssey of the dinosaurs from their humble origins on the supercontinent Pangaea, to their reign as the largest animals the planet has ever known, and finally to their abrupt demise. Much more than the story of who ate whom way back when, Dinosaur Odyssey places dinosaurs in an expansive web of relationships with other organisms and demonstrates how they provide a powerful lens through which to observe the entire natural world. Addressing topics such as extinction, global warming, and energy flow, Dinosaur Odyssey finds that the dinosaurs' story is, in fact, a major chapter in our own story.
Chapter 2
Stardust Saurians
About 14 billion years ago, the universe flared forth in the big bang, unfurling space, time, light, and matter in a singular, immense explosion. Less than one minute after this "Great Radiance," protons and neutrons emerged and combined to form nuclei of the simplest elements, mostly hydrogen and helium. About 300,000 years later, electrons combined with these nuclei for the first time, transforming matter into hydrogen and helium atoms.
An infinitesimally small amount of these atoms would one day form the bodies of all dinosaurs. About 11 billion years ago, matter condensed into billions of swirling spiral galaxies. One of these would eventually become known as the Milky Way. Within each immense galactic pinwheel, billions of stars condensed from gas and dust, igniting nuclear fusion that converted vast amounts of hydrogen into helium. After consuming most of their hydrogen fuel, a large portion of these stars -- those at least eight times the size of our sun -- generated even greater extremes of heat and temperature, forging heavier elements such as carbon, nitrogen, oxygen, silver, magnesium, copper, and iron within their interior furnaces. Ultimately, the giant stars exploded, disgorging their heavy elements into surrounding galactic space. All life on Earth would one day be formed from this wandering star dust. The shock waves from these supernovae also triggered the formation of second-generation stars, resulting in additional cycles of stellar births and deaths.
An infinitesimally small amount of these atoms would one day form the bodies of all dinosaurs. About 11 billion years ago, matter condensed into billions of swirling spiral galaxies. One of these would eventually become known as the Milky Way. Within each immense galactic pinwheel, billions of stars condensed from gas and dust, igniting nuclear fusion that converted vast amounts of hydrogen into helium. After consuming most of their hydrogen fuel, a large portion of these stars -- those at least eight times the size of our sun -- generated even greater extremes of heat and temperature, forging heavier elements such as carbon, nitrogen, oxygen, silver, magnesium, copper, and iron within their interior furnaces. Ultimately, the giant stars exploded, disgorging their heavy elements into surrounding galactic space. All life on Earth would one day be formed from this wandering star dust. The shock waves from these supernovae also triggered the formation of second-generation stars, resulting in additional cycles of stellar births and deaths.
About 4.6 billion years ago, our sun, an average-size second-generation star, formed in an outlying spiral arm of the Milky Way galaxy, about 26,000 light-years from the nucleus. The remaining debris disk of gas and dust orbiting the primordial sun condensed into eight planets, together with a bunch of smaller planetoids and moons. The heavier elements -- including the atoms that would one day walk the Earth as Stegosaurus and Velociraptor -- were concentrated closest to the central star, forming the four rocky worlds we know as Mercury, Earth, Venus, and Mars. Abundant debris remained in the early solar system, however, and impacts with the planets were common place. Earth, the third rock from the sun, experienced a particularly violent impact from a Mar-sized world about 4.5 billion years ago. This fortuitous collision carved off a huge chunk of our globe, ejecting countless molten moonlets into Earth's orbit. In less than a century, these moonlets coalesced to from our moon. The moon stabilized Earth's axis of rotation and helped set up conditions for life, including the cyclical rise and fall of oceanic tides.
The extraterrestrial bombardment persisted through most of Earth's first eon, the Hadean, finally coming to an end about 3.9 billion years ago. The effects of this meteoric barrage remains visible on the heavily cratered surface of the moon, which has undergone minimal change during the succeeding billions of years. Earth, in contrast, has always been a dynamic world, receiving regular face lifts from above and below. The Hadean Eon, -- named after Hades, the mythological hell of the Greeks -- is an apt name for earth's primordial phase. As the planet was being pummeled from space, geologic turmoil boiled within, generating great bouts of volcanism and the heaving, molten surface. About 4 billion years ago, Earth's crust formed soon after (in the deep time sense), torrential rains began to fall, eventually forming expansive oceans.
Perhaps 3.8 billion years ago (the fossil evidence is equivocal), the dinosaurian thread came to life, literally, animated by single-celled bacteria. Referred to as prokaryotes, these microscopic bits of stardust -- Earth's first life-forms -- appeared shortly after the planet was cool enough to sustain water. The origin of life remains a mystery, but its rapid emergence suggests to some that life may not have been a lottery-like stroke of luck but a virtual inevitability, given the right conditions. Despite their diminutive sizes, and lacking even a nucleus, these early bacteria were complex. Like us, they had active metabolisms, consuming energy and carrying out hundreds of chemical transformations involving vitamins, proteins, sugars, nucleic acids, carbohydrates, and fats. The environment in which life first evolved remains in question; candidates include the planetary crust miles below the surface and hydrothermal fissures on the ocean floor. (Sampson, pp. 25-26)
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