Information about dinosaurs (1)
What is a dinosaur?
In ancient times, there used to be a group of strange creatures-dinosaurs. They ruled the earth, lived for nearly 15 thousand years, and finally died out magically. Everything we know about dinosaurs today comes from dinosaur fossils.
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 eating habits are concerned, dinosaurs have tame vegetarians and fierce carnivores, as well as omnivorous dinosaurs who are both vegetarian and vegetarian.
Dinosaurs were reptiles that once ruled the earth. At present, there are more than 800 known dinosaur species, which are divided into two categories: Diptera and Bird Diptera. Among them, there are vegetarians and meat eaters; Some are stupid, others are flexible; Some crawl on land, some jump and run, and some fly in the air. In recent years, an upsurge of digging, researching and developing dinosaurs has risen quietly all over the world, and attracted the attention of biologists, geographers, sociologists and even philosophers.
The countries with the largest dinosaur resources in the world are China, the United States, Canada, Mongolia, Argentina and Brazil. The most famous places in China are Yunxian County in Hubei, Erenhot in Inner Mongolia, Xixia in Henan, Zigong in Sichuan, Lufeng in Yunnan and Heyuan in Guangdong. Only Yunxian County, Hubei Province can really compare with Heyuan City. Experts found that the dinosaur resources in Heyuan City and Yunxian County of Hubei Province have two things in common. First, the first discovery of dinosaur eggs was in the 1970s, and the real discovery of dinosaur eggs was in1March, 996. 2. The dinosaur bones were discovered in Yunxian County, Hubei Province/KLOC-0 in July, 1997, and were identified by experts as "the first symbiotic place of dragon eggs in China, which is very rare in the world", while the keel fossils were discovered in Heyuan City/KLOC-0 in July, 1999, which was the second symbiotic place of dragon eggs in China.
early discovery
Although dinosaur fossils have existed on the earth for tens of millions of years, it was not until the nineteenth century that people knew that such a strange animal had existed on the earth. The first dinosaur fossil was discovered by an English doctor named gideon algernon. Dr mantel usually has a hobby of collecting rocks and fossils. In A.D. 1820, he and his wife Marian discovered some huge teeth embedded in rocks. Dr mantel has never seen such big teeth. When he found more bones nearby, he began to study these unusual discoveries seriously. After some efforts, Dr. Mantel came to the conclusion that these teeth and bones should belong to a huge reptile. He named this unknown animal Iguanodon, and its original scientific name was Iguanodon's teeth. Soon, the bones of two giant reptiles were found in Britain, which were named Ban Long and Forest Dragon respectively. It was not until A.D. 184 1 year that these giant reptiles got their official names. At that time, an outstanding scientist, Sir richard owen, named them dinosaurs, whose scientific name means terrible lizards. Since then, the upsurge of dinosaur research has been unveiled, and scientists all over the world have become interested in digging dinosaurs.
Scenes of the dinosaur era
Dinosaurs lived on the earth10.5 billion years ago. During 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 continents drifted around the world, the climate and environment also changed. Land mass drift, coupled with climate change, has caused great changes in plant species on the earth. But because these changes are gradually formed in a very long time, the animals growing in them can still adapt well. In the early dinosaur era, the dwarf shrubs composed of ferns were the main vegetation on the earth. Later, tall coniferous forests and low cycad jungles replaced ferns and became the main plant landscapes on the earth. Soon after, the first flowering plants appeared, and the plant landscape on the earth changed greatly. Many plants and flowers that dinosaurs lived on at that time still live on the earth today.
Big monsters and small brains
Many people think that dinosaurs are giants as tall as giant trees. In fact, many dinosaurs were petite and not as high as human knees. Among the terrestrial creatures that have appeared on the earth, the herbivorous sauropod dinosaur is the largest, and Brachiosaurus is one of the best. Brachiosaurus weighed about 70 tons and was 22 meters long. Its height is 12 meters, which is equivalent to the height of four floors! Recently, people have unearthed dinosaur fossils larger than brachiosaurus-dragon and super dragon. According to calculation, the super dragon is one third bigger than Brachiosaurus, and its weight before death may be as heavy as twenty elephants! Compared with these gentle behemoths, the beautiful jaw dragon is much more agile and light. Megalodon is a small carnivorous dinosaur that may not weigh as much as a cat.
Long-necked monster
Liang Long and Mamen Xilong, one of the largest dinosaurs that once lived on the earth, belong to sauropods. Liang Long has a very long neck and tail. By contrast, his head is very small. Although it seems strange, it fits their way of life. The long neck enabled Liang Long to eat the leaves at the top of the tree, such as the common conifer leaves at that time. The small head made it easy for Liang Long to dive into the bushes and eat plants that other dinosaurs seldom ate. This foraging skill can only be achieved through Liang Long's strong, light, soft and flexible neck. When Liang Long has eaten all the food in an area, they will look around for new food together. When Liang Long was attacked by carnivorous dinosaurs, their strong trunk and whiplike long tail were their best defensive weapons.
Ancient footprints
Dinosaurs not only left fossils as evidence of survival, but also left footprints on the surface. These footprints were left when dinosaurs walked through the soft and muddy banks in search of food and water. Later, these footprints were dried and hardened by the sun, and rain and flood carried a lot of sediment to bury them. Slowly, they became fossils. These fossils are called trace fossils because they do not belong to animal bodies. Trace fossils provide a lot of information about dinosaur behavior. For example, among a large group of identical footprints, smaller footprints are often found. Scientists speculate that these small footprints may have been left by small dinosaurs protected in the middle when dinosaurs moved in groups.
Dinosaur's feeding habits
Many people think dinosaurs are terrible carnivores. In fact, many dinosaurs were gentle herbivores, just shuttling between trees and tearing leaves at the treetops to eat. Some dinosaurs, like humans, were omnivores that ate both meat and plants. As for carnivorous dinosaurs, they don't just eat dinosaurs. Anything that moves, such as insects and birds, is their prey. From the remains of dinosaur fossils, we can know many eating habits of dinosaurs before their death. One of the most important clues comes from the shape and arrangement of dinosaur jawbones and teeth. In addition, the shape of the whole dinosaur skeleton can also provide some clues. For example, carnivorous dinosaurs usually had a big head and a short and powerful neck to tear off the meat of their prey and eat it. On the other hand, most herbivorous dinosaurs had long necks, which made it easier for them to feed on the leaves at the top of trees.
Information about "dinosaurs" (2)
The first dinosaur bone fossil was discovered and collected by Robert prout, the curator of Oxford Museum in England, in 1677. More than a hundred years later, many explorers and scholars discovered and studied the fossils belonging to dinosaurs, but almost none of them were correctly identified.
184 1 year, paleontologist richard owen put forward the word "dinosaur" for the first time based on some large reptile fossil specimens, which originated from the Greek words "deinos" (meaning terror) and "sauros" (meaning lizard) and was translated as "dinosaur" by Japanese and China scholars.
After the concept of "dinosaur" came out, scholars carefully observed and identified the dinosaur fossils found, and carried out further excavation work. The excavation of Asian dinosaurs was not carried out until after the 20th century. The earliest dinosaur fossils in China were found in 1902 (Heilongjiang), and then a large number of dinosaur fossils were found in many parts of the country, including Lufeng in Yunnan, Laiyang in Shandong, Zigong in Sichuan, Tibet, Inner Mongolia and other places. Lufeng and Zigong also established dinosaur museums respectively, and held the "Lufeng First Dinosaur Festival" in 199 1. China can be called "the dinosaur country of the world".
So far, there are more than 2000 dinosaur fossils (including bones, teeth, skin, eggs, feces, footprints, etc. ) Digging around the world. It has been identified that there are more than 800 species belonging to more than 350 genera of 2 orders and 7 suborders (some scholars believe that the number of dinosaurs surviving on the earth is between 900 ~ 1200 genera), and there are more than 80 genera in China.
The earliest dinosaur fossils have been excavated about 230 million years ago. It is generally believed that dinosaurs were differentiated from the original crocodiles. At first, dinosaurs were some bipedal carnivorous dinosaurs. By the end of Triassic, the evolutionary branch of dinosaurs was basically completed. By the end of Jurassic, dinosaurs developed greatly, surpassing the pioneers of Triassic in species and quantity, and became the real rulers on the earth. Extensive adaptive radiation has also emerged.
"dinosaur" is not a taxonomic term, but a popular name. There are two kinds of dinosaurs:
1. sauropods' main feature is that the structure of ilium, ischium and pubis that make up the belt is similar to that of other reptiles, that is, a belt with three guns or three guns. It is divided into two sub-orders:
(1) Theropoda: Tyrannosaurus Rex, Deinonychus, Slender Dragon, Slender Dragon, etc.
(2) sauropods: Liang Long, Lei Long, Lufenglong, Mamenxilong, etc.
2. The main feature of flapping-wing machine is that the structure with bone is similar to that of birds, and the pubic bone is backward, that is, the four-shot or four-shot belt, and there are also front teeth and buccal muscles. It is divided into five suborders:
(1) ornithopoda: Iguanodon, duck-billed dragon, etc.
(2) Ceratosaurus: protoceratops, Ceratosaurus, Parrotbill, etc.
(3) Ankylosaurus: Arthropod, Spinosaurus, Ankylosaurus, etc.
(4) Stegosaurus: Stegosaurus, etc.
(5) Leonidas: pachycephalosaurus, etc.
Dinosaurs were all extinct in the late Cretaceous of Mesozoic-early Paleocene of Cenozoic 60-70 million years ago. This ancient animal group, which has lived on the earth for more than 100 million years, mysteriously disappeared on the earth, causing many scholars to guess and explain the reasons, and it is still inconclusive. There are several explanations that still occupy a place in today's scientific community: asteroid impact theory (Becker theory), periodic extinction theory (Nemesis theory), climate deterioration theory, community succession theory, etc. The main reason why these explanations are not recognized is that they can't be justified and can't perfectly explain why dinosaurs became extinct in about 500 ~ 654.38+00000 years.
The reasons for the extinction of many reptiles, such as dinosaurs, are described in zoology textbooks, which belong to the theory of climate deterioration and gradual change. Skeptics believe that dinosaurs formed considerable adaptability to various environments in the long-term evolution process, otherwise they would have been eliminated. The deterioration of the earth's climate should be gradual or local, and dinosaurs seem to be able to adapt or avoid it slowly. In the early and middle Mesozoic, there were many major changes in landform and climate, but dinosaurs were not greatly affected. Even if the deterioration of the earth's climate will lead to the extinction of dinosaurs, it is partial. This is not the case all over the world. There are also some small areas with little climate change, where dinosaurs will not be extinct at the same time as dinosaurs in other places. In short, the real reason for the extinction of dinosaurs is still unclear. I believe that the mystery of the extinction of dinosaur families will be solved one day.
For nearly half a century, scientists have accumulated some information about the biological characteristics of dinosaurs.
Dinosaurs' limbs (especially belts) are similar to mammals (that is, they can stand upright under their bodies and "strut" or run on the ground. Dinosaurs of general size (several meters to more than ten meters in length) usually have a stride of about 2.75 ~ 5 meters and can reach 5 ~ 8 meters when running; The running speed of small dinosaurs can reach 35 ~ 40km/h, that of large dinosaurs can reach 15 ~ 20km/h, and the slowest one is only 3.5km/h. ..
Most dinosaurs were herbivores. They ate a lot. Sauropods weighing several tons to dozens of tons eat more than 100 kilograms or even more than one ton a day. There are few kinds and numbers of carnivorous dinosaurs. According to statistics, only 3 ~ 5 of every 100 dinosaurs are carnivorous.
Dinosaurs are oviparous animals, and a few may be oviparous. During the reproductive period, males often fight for females or seduce their spouses with euphemistic guttural sounds. Eggs are 80 ~ 300mm in diameter and 2 ~ 7mm in shell thickness. Most of them are hatched by sunlight, and a few may hatch like hens. Some newly hatched young dinosaurs are well developed and can move freely; Others are underdeveloped and weak, and need careful care and feeding from their mothers for a period of time before they can live independently (for example, the duckbill dragon is also called "the mother dragon"). Dinosaurs generally live for several years to decades, and a few can live for as long as a hundred years.
Scientists usually think that dinosaurs were "warm-blooded animals", but now some scholars think that some dinosaurs may be "warm-blooded animals". Buck, a famous American vertebrate paleontologist, believes that warm-blooded animals have low energy conversion rate and few Haval blood vessels, which are the exchange places of calcium and phosphorus in bones, while warm-blooded animals have abundant blood vessels to meet the needs of energy metabolism. After comparing the microstructure of long bone grinding plates of lizards, dinosaurs and mammals, Buck thought that dinosaurs might have "thermostats". When dinosaurs walked and ran, they usually relied on the long tail, long neck, bone plate on the body surface, enlarged nasal cavity and large venous sinus in the brain to dissipate heat.
Dinosaurs have scales on their bodies, and some may have feathers or hairy skin derivatives. They may have as rich colors as birds, especially small and medium-sized species. The color of larvae is more dazzling than that of adults, while the color of large species is monotonous. The species living in the Woods are mixed with green, brown or yellow, while the species in the wilderness are mostly black and white.
Many people think that dinosaurs are huge and terrible animals, which is not comprehensive. Some dinosaurs are really big (the dragon is 42.67 meters long), but some dinosaurs are almost as big as chickens.
According to various studies, the characteristics of dinosaurs can be described as follows:
There is a socket in the belt. Vertebral healing is recommended for II ~ VII. Four feet or two feet stand upright under the body and walk on the ground with phalanges, with 3 ~ 5 claws or hooves at the toes; Rough skin, covered with scales or bone nails; It is a warm-blooded animal, oviparous (a few may oviparous); Most of them have teeth, are mostly phytophagous and eat less meat; The skull structure is similar to that of a crocodile. Recently, dinosaur fossil-bearing strata belonging to the Early Cenozoic Paleocene have been discovered in China, the United States and other places. Some scholars speculate that the last place where dinosaurs "disappeared" was probably in the south of China. At present, there is a saying that "someone has seen a living dinosaur", which is still a mystery until the scientific community obtains a real living or dead dinosaur specimen.