Extinction time
Dinosaurs first appeared in the late Triassic period about 235 million years ago and died out in the late Cretaceous period about 65 million years ago.
The origin of the name
In fact, human beings have a long history of discovering dinosaur fossils. Long before the discovery of Iguanodon, Europeans knew that there were many grotesque huge bone fossils buried underground. It was not until paleontologist Mantel discovered Iguanodon and compared it with iguana that the scientific community initially determined that it was a group of extinct lizard-like reptiles. dinosaur
1842, British paleontologist Charles Owen coined the word "dinosaur". English dinosaurs came from the Greek deinos (scary) Saurosc (lizard or reptile). For Owen at that time, this "scary lizard" or "scary reptile" refers to an extinct large reptile (actually it is not). In fact, not many dinosaurs were found at that time. Since the discovery of dinosaur fossils in Antarctica in 1989, dinosaur remains have been found in seven continents all over the world. At present, there are at least 650 to 800 genera of dinosaurs described in the world (species and genera in paleontology are not completely different from the classification of modern animals). Later, scholars in China, Japan and other countries translated it into a dinosaur, because there have been legends about dragons in these countries, which think that dragons are the length of scale worms and snakes are another name for dragons.
Relationship with modern animals
1862 The archaeopteryx fossils found are very similar to those of Megalodocus, but the difference is that the archaeopteryx fossils have obvious feathers (Megalodocus also has feathers, but it is very primitive). In fact, quite a few carnivorous dinosaurs have primitive feathers, which indicates that dinosaurs and birds may be close relatives. Since 1970, many research reports have pointed out that modern birds are probably the direct descendants of theropod dinosaurs. Crocodiles are modern close relatives of another kind of dinosaurs, but their relationship is farther than that between dinosaurs and birds. Dinosaurs, birds and crocodiles all belong to the evolutionary branches of primitive dragons, which first appeared in the late Permian and became the dominant fauna in the middle Triassic. Mammals originated from reptiles, whose predecessor was "mammal-like reptiles" and early was "reptile-like mammals". Most of Mesozoic reptiles died out at the end of Mesozoic. Some reptiles (such as turtles, snakes, crocodiles, etc. ) has adapted to the ever-changing environment and has been preserved; Some of them evolved into birds and mammals today along different evolutionary directions.
Diversified development
dinosaur
From the early Jurassic to the late Cretaceous, the dinosaur family adapted to the environment and developed rapidly, which led to the diversification of dinosaurs and the increase of dinosaur population, which gave dinosaurs an advantage and enabled them to dominate the earth's ecosystem. There are many kinds of dinosaurs, and their shapes and habits are quite different. Among them, the big one can be as big as dozens of elephants combined; Small, but almost like a chicken. As far as food habits are concerned, dinosaurs have mild vegetarians (dinosaurs that ate plants) and fierce carnivores (dinosaurs that ate animals), as well as omnivorous dinosaurs that ate both plants and plants.
Biological habit
The oldest reptile fossils can be traced back to the "Pennsylvanian period" of Paleozoic (about 320 million years ago-280 million years ago). Tracing back to the source, it evolved from amphibians. Amphibian eggs need to be in water to start developing. Reptiles have evolved eggshells to prevent water from escaping from eggs. This major reform enables reptiles to survive without water. From 245 million years ago to the Mesozoic era 65 million years ago, reptiles became the master of the earth's ecology, so the Mesozoic era was also called the reptile era. Large reptile dinosaurs appeared in the early Mesozoic. The fragile herbivorous double-chambered dragon is the largest land animal in size and weight. Spinosaurus is the largest carnivore on land. In addition, ichthyosaurs living in the sea, plesiosaurs living in the air and pterosaurs formed a complex and perfect ecosystem (marine reptiles and pterosaurs are not dinosaurs). Reptiles have multiplied on the earth for about 65.438+0.8 billion years. Among the animals of this era, dinosaurs are the most widely known. When people mention dinosaurs, they will see a huge and fierce animal. In fact, there are also small and docile species among dinosaurs.
Dinosaur migration
For a long time, paleontologists were not sure whether dinosaurs migrated like birds or wildebeests. Because of the possible threat posed by carnivorous dinosaurs, it is not a far-fetched idea for herbivorous dinosaurs to migrate on the grassland. Now, researchers at the University of Colorado in the United States have proved for the first time that dinosaurs also migrated when their living environment deteriorated. Researchers used oxygen in tooth fossils to prove for the first time that dinosaurs migrated between flooded plains.
Dinosaur habit
The body structure of Tyrannosaurus Rex
Because dinosaurs are extinct, we can't study them by studying living animals. We can only rely on dinosaur fossils left over from the earth to study them. Paleontologists speculate on the shape and habits of dinosaurs through the study of dinosaur fossils. According to their research, dinosaurs are like living animals: there are big ones and small ones; Some walk on two legs, and some walk on four legs; Some eat plants, some eat animals, and some eat plants and animals; Some have smooth skin, some have scales or bones, some have horns or shields on their heads, and some have long thorns on their tails. It is similar in that all dinosaurs have small brains (except some carnivorous dinosaurs) and lay eggs on land (all dinosaurs are the same).
Editing this dinosaur era
Giant chief fossil
Dinosaurs lived on the earth for 65.438+0.6 billion years. In such a long time, many changes have taken place in the environment of the earth. The Pangu continent, which was originally connected as a whole, gradually drifted and split into the familiar form. After these earth plates drifted around the world, the climate environment changed because the light was no longer uniform and the heat conduction was blocked by the ocean. In the early dinosaur era, the dwarf shrubs composed of ferns were the main vegetation on the earth. Plate drift, coupled with climate change, has caused great changes in plant species on the earth. However, because these changes took place gradually over a long period of time, the animals growing in them can still adapt well. However, due to the intensification of crustal movement and frequent geological activities in the middle period of dinosaur era, the land climate changed. In the late dinosaur era, the climate became dry and cold. There is a desert on the earth, and the mountains are uplifted by the drift of the earth's plates. The deep valley sinks and the plates move the mainland in different directions, which makes a series of earth-shaking changes in the environment.
Editing this fossil discovery
In history, humans discovered dinosaur fossils very early. It was only because of the limited level of knowledge at that time that these fossils could not be correctly explained. According to legend, as early as 1700 years ago, dinosaur fossils were found in Wucheng County, Sichuan Province (then called Shu County of Bashu). But people at that time did not know that it was the remains of dinosaurs, but regarded them as the bones left by the legendary dragons. Long before Iguanodon (the first named dinosaur) was discovered in Mantels, Europeans knew that there were many grotesque huge animal bones buried underground. But at that time, people didn't know their exact ownership, so they were always mistaken for "the remains of giants." According to the clues found in a historical novel "Mr. milken's Wife", a researcher named Hastert announced that he had finally found the following research results: 1677, a man named prout-in this book, prout Gallon described a huge fossil leg bone found in a quarry in the parish of Carovella. Prout-Garonne province drew illustrations for this fossil, and pointed out that this thigh bone is neither cow's, horse's, nor elephant's, but belongs to a giant bigger than them. stegosaurus
Although prout-Garonne Province didn't realize that this fossil belonged to a dinosaur, or even associated it with reptiles, the specimen he recorded in writing and depicted by himself with illustrations has been identified by later paleontologists as the thigh bone of a dinosaur called Megalodon (now known as Bancrosaurus), and this fossil was discovered earlier than the first named dinosaur, Iguanodon, in Mantels 145 years. Therefore, Hastert thinks that prout-Garonne Province should be the first discoverer and recorder of dinosaur fossils in history.