The Handy Dinosaur Answer Book. Patricia Barnes-Svarney
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Название: The Handy Dinosaur Answer Book
Автор: Patricia Barnes-Svarney
Издательство: Ingram
Жанр: Сделай Сам
Серия: The Handy Answer Book Series
isbn: 9781578593262
isbn:
When was the first dinosaur bone collected and described?
The fossilized bones of dinosaurs have probably been found throughout human history, but for much of this time people did not realize what they were. Therefore, no records or descriptions were kept until fairly recently. References to fossilized sharks’ teeth and shells are recorded from the European medieval period, but because they believed that no animal or plant made by God could become extinct, they explained them in other ways. For example, many of the fossils were interpreted as the remains of modern species as opposed to ancient, extinct species; others were thought of as merely pebbles that resembled the remains of animal and plant species.
The first recorded description of a dinosaur bone was made in 1676 by Robert Plot (1640–1696), a professor of chemistry at the University of Oxford, England, in his book The Natural History of Oxfordshire. Although he correctly determined that it was a broken piece of a giant bone, Plot did not know the bone came from a dinosaur. Instead, he felt it belonged to a giant man or woman, citing mythical, historical, and biblical sources. In 1763, the same bone fragment was named Scrotum humanum, by R. Brookes, to describe its appearance, but the name never gained wide, or serious, acceptance. Based on Plot’s illustration, modern scientists believe the bone fragment is actually the lower end of a thigh bone from a Megalosaurus, a meat-eating dinosaur from the Middle Jurassic period that roamed the area now known as Oxfordshire.
In 1787, American physician Caspar Wistar (1761–1818) and Timothy Matlack (better known as a statesman and patriot during the American Revolution; 1730–1829) discovered a large fossil bone in the state of New Jersey. Although they reported their finding, it was ignored and unverified; it may have been the first dinosaur bone ever collected in North America.
What are some of the oldest dinosaur fossils found to date?
There are several dinosaur fossils claimed to be the oldest ever found, a claim many scientists have made in recent years. The oldest dinosaur bones and skulls found to date may be of a small genus of meat-eating animal measuring about 6.5 feet (2 meters) in length, but some scientists believe it was another type of reptile called a thecodont. The fossils were discovered in Brazil and are thought to be 235 to 240 million years old.
Previously, an Eoraptor, a 228 million-year-old meat-eating dinosaur, was found in Argentina. More recently, paleontologists also discovered the fossilized bones of three prosauropods, plant-eating dinosaurs that lived approximately 220 million years ago in Santa Maria, an area of southern Brazil. And finally, another claim to the oldest-known “dinosaurs” (or precursors) were prosauropods from Madagascar thought to be 230 million years old. The Eoraptor was dated using radio-isotope analysis, whereas index fossils—or the use of surrounding fossils to date a “dinosaur”—were used to date the fossil in Madagascar.
What is a dinosaur?
Dinosaur is a term used to describe certain types of animals that lived during the Mesozoic era in geologic history. It is difficult to generalize about dinosaurs, but two things are definitely agreed upon. They were, in general, the largest creatures to ever walk on Earth, even though there were many smaller species of dinosaurs. In addition, these animals were some of the most successful organisms that ever lived, existing as species for at least 160 million years.
What does the term dinosaur mean?
Dinosaur comes from the term dinosauria, which is a combination of the Greek words deinos and sauros. It means “terrible reptiles” or “terrible lizards.” The term was invented by the well-known British anatomist Sir Richard Owen (1804–1892). He coined the term in 1842 to describe the 175-million-year-old fossil remains of two groups of giant reptiles that corresponded to no known living creatures. In 1854, Owen prepared one of the first dinosaur exhibits for display at the Crystal Palace in London, England.
DINOSAUR ANCESTORS
How did life evolve after the early one-celled organisms?
Over hundreds of millions of years after the evolution of single-celled organisms, the oceans abounded with a huge variety of life. The first soft-bodied animals, such as worms and jellyfish, evolved toward the close of the Pre-Cambrian (also seen as Precambrian) era roughly 600 million years ago; the first animals with hard parts, such as shelled mollusks, evolved during the first period after the Pre-Cambrian known as the Cambrian period of the Paleozoic era.
What are vertebrates?
The first vertebrates, or animals with backbones, evolved during the late Cambrian to early Ordovician periods as jawless freshwater fish that looked much like today’s hagfish and lampreys. By the Devonian period (the “age of fishes”), jawed and armored fishes dominated the oceans. Around 380 million years ago, a line of fish with bony skeletons developed air-breathing lungs and “limbs” strong enough to support them. These were the precursors to the amphibians, creatures that made their first move toward land probably in response to the spread of plants to land around the early Silurian period.
What were the early amphibians and when did they live?
Amphibians were the first air-breathing land vertebrates, evolving from lobe-finned fish and primitive tetrapods. Tetrapods were animals with fishlike heads and tails, and with limbs that were little more than jointed, lobed fins. They evolved around 340 million years ago during the late Devonian period. So far, the oldest of these pre-amphibian fossils have been dated at approximately 360 million years old. These animals could do something that no fish could do: breathe air. The changeover from gills to lungs came during the early larval stage of the amphibian. These early amphibians were direct descendants from the early fish, and represent an important transitional stage from water-dwelling to land-dwelling animals. They were also the first vertebrates to eventually evolve true legs, tongues, ears, and voice boxes.
The word “amphibian” comes from the Greek amphi, meaning “both,” and bios, meaning “life” (sometimes translated as “living a double life”). The name signifies that these animals could live both in and out of the water.
Still around today, jellyfish were some of Earth’s first soft-bodied life forms (iStock).
The Carboniferous period of the Paleozoic era, from approximately 360 to 280 million years ago, brought about a proliferation of amphibians, as did the Permian, from about 280 to 248 million years ago. Much of the world’s climate during both time periods was warm and humid, with many swamps, marshes, and lakes dominating the landscape—a perfect environment for the water needs of the amphibians. In some texts, the Carboniferous or the Permian periods are called the “age of amphibians” (although many scientists agree that reptiles began to take over the amphibians’ domain during the Permian).
What were some of the earliest species that led to СКАЧАТЬ