In the Mesozoic Era more than 200 million years ago, many reptiles lived on land, so the Mesozoic era is also known as the "reptile age". They continually differentiated into different kinds of reptiles, some of which became today's turtles, some of which became today's crocodiles, some of which became today's snakes and lizards, and one of which evolved into the mammals that spread throughout the world today.
Dinosaurs were the largest of all terrestrial reptiles and were well suited to living in swampy areas and shallow lakes, when the air was warm and humid and food was easy to find. So dinosaurs ruled the earth for more than 100 million years, but for some reason, they suddenly went extinct for a short period of time 65 million years ago, and today people see only a large number of dinosaur fossils left behind at that time.
Through fossils, people have discovered and learned about the dinosaurs that lived on the earth tens of millions of years ago, and it can be said that dinosaur fossils have opened a new door to the world for us.
Five major extinction periods have been identified:
● Late Ordovician (about 445 million years ago)
● Late Devonian (about 370 million years ago)
● Late Permian (about 250 million years ago)
● Late Triassic period (about 200 million years ago)
● Late Cretaceous period (c. 65 million years ago)
The production of dinosaur fossils
Wilson believes that the worst mass extinction in history is taking place due to the impact of human habitation on the earth, especially the growth of the population and the development of the earth's resources.
Back in the Cambrian period (505 million to 543 million years ago), when the first marine invertebrates appeared, we can now find remnants of them exposed in lakes and shale in the mountains. Nestled in Burgess Shale in the Rockies near British Columbia in the Rockies Mountains. The Burgess Shale has an important fossil resource, and the remains of invertebrates are deposited on it after they die. At that time, this area was probably located near the equator. The Burgess Shale contains a large number of organisms, which are very well preserved when compressed into shale.
Presumably, the creatures were swept to this location by mudslides falling from high cliff faces. These organisms and animal fossils are well preserved and abundant. These specimens contain the small mollusk Maltaceae. The fossils appear on the rock surface as highly compressed flake structures, and some of their complex three-dimensional structures can still be seen. Also included in the specimen is the oil-like ctenophora, the largest trilobite species found in shale, whose soft appendage structure is as well preserved as bone. Sponges have also been found in specimens; Lower Cambrian tyrozoans are "bivalve" crustaceans similar to modern brineworms; and Ottoya is a worm-like organism with a snout and pharyngeal tooth structure at one end of its body. All of these findings have allowed scientists to classify early, diverse life forms that later disappeared.
Fossils formed during the Triassic period are particularly dazzling. We can see giant dinosaur specimens on display in the Science Museum. The first appearance of dinosaurs dates back to the Triassic and Jurassic periods, when feathered birds and large plant-eaters appeared. The Cretaceous period was the final stage of the age of the dinosaurs. The extinction of the dinosaurs is presumed to have occurred during the Tertiary period, when dinosaurs disappeared and mammals and birds took their place and developed into dominant species.
The mystery of the extinction of the dinosaurs
Why the dinosaurs went extinct is controversial. One theory is that dinosaurs disappeared 65 million years ago, when almost a third of all plant and animal species on Earth went extinct. After examining soil, rock and fossils, scientists speculate that a catastrophic event occurred. One guess is that an asteroid or comet hit Earth, causing smog pollution that led to the death of plants (food suppliers) and eventually led the dinosaurs toward mass extinction. This apparently occurred during the Cretaceous and Tertiary geological periods. Others believe that Earth has been hit by asteroids and comets for hundreds of thousands of years.
There is also a theory that extinctions occurred at different times for a number of reasons, including volcanic eruptions, microbes and climate change. There is no scientific consensus on the causes of the extinction of the dinosaurs, but whatever the cause, it must include accidental events that triggered the extinction. Although there are as many as trillions of dinosaur footprints, there are few traces of such footprints in rocks and shales. Interestingly, there are many kinds of dinosaurs of different sizes and shapes. The evolutionary process provides an explanatory framework for these to occur. This leads to a probability-based assumption in which chance plays a role in natural selection.
The fossils clearly record the diversity of prehistoric dinosaur species and all other species. Paleontologists say that at the end of the Triassic period, only 40 known dinosaur species existed. However, during the Cretaceous period, the variety of dinosaurs increased rapidly, with at least 245 species of dinosaurs during this period. During the 160 million years that dinosaurs ruled the planet, their diversity increased significantly whenever they entered a new habitat. They are forced to become more adaptable to special circumstances. Because there is also a geological fossil record that has not yet been discovered by paleontologists, it is impossible to reconstruct history comprehensively. Apparently, many small pieces of the species puzzle have been lost.
Fossils – the most intuitive evidence for the evolution of dinosaurs
In 1842, the British scientist Sir Richard Owen coined the term "dinosaur", which has its roots in the Greek words "deinos" and "sauros", the former meaning "amazing" or "terrible", and the latter representing "lizard". Dinosaurs differed from other prehistoric creatures in that they had upright legs and three or more vertebrae that supported the pelvic or hip bones. They are classified as reptiles. There are traces of dinosaurs in various regions of the earth, when the earth's climate was very different from today's, and there was more carbon dioxide in the atmosphere, and there was a so-called greenhouse effect. At that time, the pattern of the oceans and continents was also markedly different from that of today: the continents were now connected supercontinents, and the oceans were only part of a vast ocean. Over time, the Earth's crust continued to move, slowly dividing into northern and southern continents, and continued to change. Dinosaur metabolism was significantly slower to adapt than other living organisms.
Many different kinds of dinosaur skeleton remains have been excavated. Dinosaurs found in the Zigong region of China exhibit a wealth of diversity. They include Li's Shu dragon (medium-sized dinosaur 9 to 12 meters long), Tianfu Emei dragon (about 20 meters long), salt-toothed Dulong (bipedal walking, small dinosaur about 1.4 meters long), and Yang's Mamenxi dragon (a large dinosaur 16 meters long).
A large number of extinct animals from this period have been inventoried. The catalog covers about 1,000 species of dinosaurs and pterosaurs arranged in English from A to Z – from Awakening, Brachiosaurus, Thunderosaurus to Demon Dragon. There are also huge bird-like animals that have either become extinct or have become the ancestors of modern birds. In addition, there are similar aquatic and marine reptiles, which are known as plesiosaurs and ichthyosaurs. There are still new fossils that continue to be unearthed, such as the huge Fossil Ofon found on a Norwegian island about 800 miles from the North Pole in 2009. The behemoth moves underwater with four powerful fins and feeds on fish, squid-like creatures, and reptiles. It has a slender skull and a strong jaw 10 feet long, and is 50 feet long and weighs 45 tons. Apparently they lived during the Jurassic period and were not directly related to the dinosaurs that lived on land.
The vast remains of dinosaur fossils are the unspoken proof that these creatures have survived, hunted, fought, multiplied and died on Earth for millions of years – and to this day they have disappeared from the earth. What a spectacular performance – a history of the rise and fall of a dinosaur family. These creatures were replaced by birds and mammals that later appeared on Earth, which also repeated similar cycles of life during evolution, although many of their descendants still exist today. Seeing a restored model of the skeleton of the Tyrannosaurus rex on display in the Natural History Museum is both amazing and shocking. Michael Crichton depicted such creatures in his novels and was later remade into the movie Jurassic Park. All of this proves that both chance and randomness play a role, both then and now.
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The ideas in this article come from
The Turbulent Universe
【Executive Summary】
This book is one of the "shelves of scientific thinking" and constructs a global ethical picture based on scientific wisdom. By merging realism and optimism, the author elaborates on a humanistic ethical code, namely the goodness and wisdom of life, which is a practical moral choice inspired by scientific wisdom. This new ethical civilization is based on a global ethic of universal human rights, free scientific exploration unconstrained by dogma, an attitude of anticipation of human potential, and the courage and determination to face the daunting challenges of our time. It is based on this global ethic that humanity can creatively find meaning in its survival through its efforts and be in awe of the vastness of the universe, nature, and the future of humanity.
【About the Author】
Paul Kurtz (1925–2012) was an Honorary Professor of Philosophy at the State University of New York at Buffalo and a Fellow of the American Association for the Advancement of Science (AAAS). He has authored and edited more than 50 books, including A priori seduction, Courage to Exist, and Embracing the Power of Humanism, with more than 900 articles and reviews. He founded and chaired organizations such as prometheus, the Institute for Scientific and Human Values, the Center for Scientific Exploration, the Council of Secular Humanism, and the Scientific Inquiry Committee. He has participated in the recording of television and radio programs many times, and has lectured at universities around the world.
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Author: (U.S.) Paul Kurtz
ISBN:9787313198969
Shanghai Jiao Tong University Press
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