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The diverse evolution of dinosaurs
Deepen these fast data on dinosaurs for children of all ages. Discover why the tyrannosaur had sharp teeth, where does the name ‘dinosaur’ come from, and more! Dinosaurs are a group of reptiles who have lived on earth for about 245 million years. In 1842, the English naturalist Sir Richard Owen coined the term Dinosauria, derived from the Greek Deinos, which means ‘terribly large’ and Sauos, which means ‘lizard’. Dinosaur fossils have been found on the seven continents. All non -avian dinosaurs were extinguished about 66 million years ago.
There are approximately 700 known species of extinct dinosaurs. Modern birds are a kind of dinosaur because they share a common ancestor with non -avian dinosaurs. Glen Rose Dinosaur Path. Paleontologists are as detectives that examine the evidence left by extinct animals. These clues about how dinosaurs were found in fossils – the ancient remains of an organism, such as teeth, bones or shells – or evidence of animal activity, such as footprints and footprints.
Everything we know about non -avian dinosaurs is based on fossils, which include bones, teeth, traces, footprints, eggs and skin impressions. For centuries, people from all over the world have discovered amazing bones and fossilized footprints. The first findings inspired legends and fairy tales, since people imagined that these bones belonged to huge giants or monsters. Some consider Barnum Brown, who began their career in the American Museum of Natural History in 1897, as one of the largest dinosaurs hunters in the late nineteenth and early twentieth century.
He began his career at the American Museum of Natural History in 1897. Many of his greatest discoveries, including the first specimens of Tyrannosaurus rex found, are exhibited in the museum’s dinosaurs rooms. Today, in addition to patience and acute observation skills, paleontologists use new technologies to solve unanswered questions about dinosaurs and other fossils. Advanced image technology, such as computerized tomographs, allows paleontologists to see the three -dimensional structure of fossils, often without having to remove the matrix.
Paleontologists incorporate biomechanics research, applying the principles of physics and engineering to rebuild the biological movement of non -aviarosinaries. The information obtained from fossil bones along with the observations of both the movement and musculature of living animal species help scientists model how non -aviac dinosaurs can have moved. The oldest known dinosaur appeared about 245 million years ago during the late Triassic period (250 to 210 million years ago).
Dinosaurs evolved to becoming a very diverse group of animals with a wide range of physical characteristics, including modern birds. Contrary to what many people think, not all dinosaurs lived during the same geological period. The stegosaurus, for example, lived during the late Jurassic period, about 150 million years ago. Tyrannosaurus Rex lived during the upper Cretaceous period, about 72 million years ago. Stegosaurus became extinct for 66 million years before Tyrannosaurus walked on Earth.
During the Mesozoic era (a period of more than 180 million years that included the Triassic, Jurassic and Cretaceous periods), a kind of non -avian dinosaur evolved to a kind of avian dinosaur. This avian dinosaur is the first bird and the precursor of all birds. Each non -avian dinosaur was extinguished 66 million years ago. There are several theories about what could have contributed to the mass extinction of non -avian dinosaurs and other species at the end of the Cretaceous period. It is true that an asteroid or mass comet hit the earth during this time, causing a dramatic change in the climate of the earth.
Some scientists speculate that this impact had catastrophic consequences for life on earth. But other factors, including changes in sea level and large -scale volcanic activity, may also have played an important role in this mass extinction. Paleontologists use fossil evidence preserved in old rocks to discover how extinct animals lived and behaved. In most cases, a fossilized bone is actually a rock made of minerals, without a trace of the original bone material. The discovery of eggs and dinosaur nests provided evidence of the behavior of some dinosaurs.
When comparing the protoceratops skulls of different ages (as in the image above), paleontologists can draw conclusions on how some dinosaurs grew. To discover how organisms lived in the past, paleontologists are looking. The jaws, the fossilized teeth and manure provide important clues about what non -avian dinosaurs ate.
A series of fossilized footprints, called clues, reveal some intriguing evidence about the behavior and locomotion of dinosaurs. Until recently it was believed that the feathers were exclusive to birds. However, recent discoveries have unearthed evidence of feathered non -avian dinosaurs. Paleontologists looking for dinosaurs fossils begin their work inspecting areas to find sedimentary rocks of the Mesozoic era. Finding the right place requires experience and good eye. Field work is just a small part of what paleontologists do.
They also work in the laboratory, examining the samples they have found, as well as the fossils collected years before. They spend a lot of time classifying specimens, examining their characteristics and determining their biological relationships. Teeth, footprints and feathers. Most the thenopod dinosaurs, such as Tyrannosaurus, had pointed teeth, slightly curved back and fed. The sharp tips drilled meat and stretch marks helped cut it by trapping and tearing muscle fibers. The carnivores did not bite or crush the food;whole pieces swallowed.
Herbivorous dinosaurs had teeth in several ways designed for their particular diets. The triceratops, for example, had hundreds of teeth that formed a solid ‘wall’ with sharp ridges. The teeth were used to cut vegetation. Other plant dining rooms, such as Anatotitan, had wide and plans tooth that they used to crush hard vegetation. Long neck dinosaurs, such as Diplodocus, had long pencil -shaped teeth they used to rake the branches of the branches. These dinosaurs swallowed the entire leaves.
They also ingested small stones, called gastrolites, which probably grind food in their stomachs, in the same way that modern birds do, such as parakeets and chickens. From an individual footprint, scientists can estimate the height of the dinosaur that did it. An approximate estimate of the leg length multiplying the print length by four. A footprint can also provide clues about the type of dinosaur that made it. A three -to -fingerprint and sharp claw.
A three fingerprint with rounded fingers probably belonged to an ornithopod dinosaur, a herbivorous. And the unequal sized footprint pairs were probably the work of four -legged dinosaurs, long neck and long tail called sauropods, another group of herbivores. Modern birds, or avian dinosaurs, have skeletal characteristics that are almost identical to those of some non -avian dinosaurs. The feathers evolved before the flight and may have worked as isolation to keep dinosaurs hot, or to exhibit them as a way of attracting couples.