Introduction
Ten years is a long time in science; there are so many discoveries and new technologies that change and add to the overall scientific field. It’s no different in paleontology—especially in the study of dinosaurs.
So now, for you, the dinosaur enthusiast, we present the new, colorful, and very updated second edition of The Handy Dinosaur Answer Book. One of the best parts of revising and updating a book is going through all the feedback we’ve heard/read over the years. And there’s no doubt about it: this book seems to be a favorite of dinosaur lovers from 6 to 96!
One of the reasons for this fascination with the great creatures has not changed in 10 years: How in the world did something as big as a house—and sometimes ferocious—roam Earth so many millions of years ago? Admittedly, the land has changed over the past 65 million years since the dinosaurs died out, but just to think that an Allosaurus or Gigantosaurus may have once stomped in your own backyard never fails to send chills up our collective human spines.
There are other reasons for dinosaur enthusiasm, especially with so many global discoveries made in the past decade: the discovery of fossilized dinosaur organs; whole or parts of dinosaur eggs and nests; imprints of dinosaur blood vessels; feather imprints galore; attempts to extract DNA from dinosaur remains; and large caches of fossils in rock formations previously thought to be devoid of dinosaur bones. There are also more and more large-boned dinosaur fossils that pop up every year, keeping alive the “size competition” between the big carnivores like the Tyrannosaurus rex and sauropods like the Brachiosaurus. How could anyone who’s a dinosaur enthusiast not be excited about such amazing discoveries?
This newly revised The Handy Dinosaur Answer Book answers over 600 of your questions about these extinct creatures, such as: From what animals did the dinosaurs evolve? Who found the first dinosaur remains? What other plants and animals lived during the time of the dinosaurs? What dinosaur remains show a heart? What are the largest—and smallest—dinosaur fossils known at this time? How did scientists extract DNA from a Tyrannosaurus rex bone? Are birds really dinosaurs? Did the first dinosaurs have feathers? Why are Argentina and China important to recent dinosaur studies? And the question and answer list goes on and on.
This book attempts to answer these questions and more, taking you through the Triassic, Jurassic, and Cretaceous periods of geologic time when the dinosaurs roamed the earth. It tells you where scientists stand in terms of dinosaur discoveries, the newer species of dinosaurs, new possible reasons for the extinction of the animals, and especially why, as more dinosaur fossils are uncovered, the ideas about the evolution of dinosaurs will continue to change.
We invite you to enjoy reading about the most amazing creatures that ever walked, ran, hopped, loped, and stomped on the Earth. As the saying goes: “Dinosaurs Once Ruled!” If the current fascination with dinosaurs is any indication, they still do.
—Patricia Barnes-Svarney and Thomas E. Svarney
Acknowledgments
This book would not be possible without the hard work and dedication of the people at Visible Ink Press. Our thanks especially go to our editor, Kevin Hile, for his wonderful editing and insightful questions, and for making this dinosaur book so user-friendly! We also want to thank our agent, Agnes Birnbaum for all her help, patience, and friendship over the years.
—Patricia Barnes-Svarney and Thomas E. Svarney
IN THE BEGINNING
How old is Earth?
Earth is currently believed to be about 4.54 billion years old, but that number came after centuries of debate. In 1779, French naturalist Comte de Georges Louis Leclerc Buffon (1707–1788) caused a stir when he announced 75,000 years had gone by since Creation, the first time anyone had suggested that the planet was older than the biblical reference of 6,000 years. By 1830, Scottish geologist Charles Lyell (1797–1875) proposed that Earth must be several hundred million years old based on erosion rates; in 1844, British physicist William Thomson, later first baron of Largs (Lord) Kelvin, (1824–1907), determined that Earth was 100 million years old, based on his studies of the planet’s temperature. In 1907, American chemist and physicist Bertram Boltwood (1870–1927) used a radioactive dating technique to determine that a specific mineral was 4.1 billion years old (although later on, with a better knowledge of radioactivity, the mineral was found to be only 265 million years old). Using different adaptations of Boltwood’s methods on terrestrial, lunar, and meteorite (space rock that falls to the surface of Earth) material, scientists now estimate that Earth is between 4.54 and 4.567 billion years old.
How old is the oldest rock and mineral found on Earth?
The oldest rock discovered on Earth, the Acasta gneisses found in the tundra in northwestern Canada near the Great Slave Lake, is about 4.03 billion years old. The oldest minerals yet found are 4.404 billion years old and were found in Western Australia. The minerals—zircon crystals—eroded from their original rock, and then were deposited in younger rock.
Gases released by erupting volcanoes, such as carbon dioxide, nitrogen, and water vapor, did a great deal during Earth’s early history to make the atmosphere life-sustaining for plants and animals (iStock).
What caused the early Earth’s water and atmosphere to form?
No one really knows how the oceans filled with water. One theory is that volcanoes released enough water vapor to allow the oceans’ waters to condense. Another theory states that comets bombarded Earth just after the formation of the solar system, bringing enough water to eventually fill the oceans.
The origin of Earth’s atmosphere is also debated, but not as intensely. In this case, it is more likely that some of the atmosphere originated from gases that were part of the solar nebula, gases brought by comets, and those produced from volcanic activity. Earth probably would have had a thicker atmosphere, too, but the young, active Sun’s heat boiled away the lighter materials—elements that are still found today around the gas giant planets Jupiter, Saturn, Uranus, and Neptune.
What gases began to accumulate after Earth’s crust finally solidified?
As Earth’s crust solidified, gases began pouring out of fissures and volcanoes, accumulating in the forming atmosphere. These same gases still emanate from modern volcanoes, and include carbon dioxide (CO2), water vapor (H2O), carbon monoxide (CO), nitrogen (N2), and hydrogen chloride (HCl).
As these gases interacted in the atmosphere, they combined to form hydrogen cyanide (HCN), methane (CH4), ammonia (NH4), and many other compounds. This atmosphere would be lethal to most present day life-forms. Fortunately for life on Earth, over the next two to three billion years the atmosphere continued to change until it reached close to its present composition.
