Information about "dinosaurs"

The first dinosaur bone fossil was discovered and collected by Robert prout, the keeper of Oxford Museum in England in 1677. After more than a hundred years, many explorers and scholars have discovered and studied the fossils belonging to dinosaurs, but almost none of them have been correctly identified.

in p>1841, paleontologist richard owen first put forward the word "dinosaur" based on some fossil specimens of large reptiles, which came from the Greek words "deinos" (meaning horrible) and "sauros" (meaning lizard) and was translated as "dinosaur" by Japanese and Chinese scholars.

after the concept of "dinosaur" came out, scholars made detailed observation and identification of dinosaur fossils found, and carried out further excavation work. The excavation of Asian dinosaurs was not carried out until after the 2th century. The earliest dinosaur fossils in China were discovered in 192 (Heilongjiang), and then a large number of dinosaur fossils were discovered in many parts of the country, including Lufeng in Yunnan, Laiyang in Shandong, Zigong in Sichuan, Tibet and Inner Mongolia. Lufeng and Zigong also established dinosaur museums respectively, and in 1991, the "Lufeng First Dinosaur Festival" was held. China can be called "a dinosaur country in the world".

Up to now, there are more than 2, dinosaur fossils (including bones, teeth, skin, eggs, feces, footprints, etc.) excavated all over the world. According to the identification, there are more than 8 species in more than 35 genera of 2 orders, 7 suborders (some scholars believe that the number of dinosaurs that have survived on the earth is between 9 and 1,2 genera), and there are more than 8 genera and more than 1 species in China.

The earliest dinosaur fossils that have been excavated are about 23 million years ago. It is generally believed that dinosaurs were differentiated from pseudocrocodiles among the first crocodiles. At first, dinosaurs were some bipedal carnivorous dinosaurs. By the end of Triassic, the evolutionary branch of dinosaurs was basically established. 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 appeared.

"dinosaur" is not a taxonomic term, but a popular name. Dinosaurs are divided into two groups:

1. The main feature of sauropods (sauropods) is that the structure of the bones, ischium and pubis that make up the belt is similar to that of other reptiles, that is, the belt with three shots or three shots. It is divided into two suborders:

(1) theropod: Tyrannosaurus Rex, Deinonychus, Leptosaurus, Leptosaurus, etc.

(2) sauropod: Liang Long, Lei Long, Lufenglong, Mamenxilong, etc.

2. The main feature of ornithoptera is that the bone structure of the belt is similar to that of birds, with the pubic bone pointing backward, that is, a four-shot or four-put belt, and in addition, it has anterior teeth and buccal muscles. It is divided into five suborders:

(1) ornithopoda: Iguanodon, Duckbilled Dragon, etc.

(2) Ceratosaurus: protoceratops, Ceratosaurus, Parrotbill, etc.

(3) Ankylosaurus: Nodulosaurus, Spinosaurus, Ankylosaurus, etc.

(4) stegosaurus: stegosaurus, etc.

(5) Leo orders: pachydantosaurus, etc.

dinosaurs were all extinct in the late Cretaceous of Mesozoic-the early Paleocene of Cenozoic 6-7 million years ago. This ancient animal group, which has lived on the earth for more than 1 million years, mysteriously disappeared on the earth, causing many scholars to speculate and explain its reasons, and there is no conclusion yet. There are several explanations that still have a place in today's scientific circles: asteroid impact theory (Bekele 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 justify themselves and can't perfectly explain why dinosaurs became extinct in about 5 ~ 1 million years.

The reason for the extinction of many reptiles, such as dinosaurs, is described in the junior middle school Zoology textbook, which belongs to the theory of climate deterioration and is a gradual change view. Skeptics believe that dinosaurs have 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 to it slowly or avoid it. In the early and middle Mesozoic, there were many major changes in landforms and climate, and dinosaurs were not greatly affected. Even if the deterioration of the earth's climate would lead to the death of dinosaurs, it would be partial. This is not the case all over the world. There are still some small areas where the climate has not changed much, and the dinosaurs there will not be extinct at the same time as the dinosaurs elsewhere. In short, the real reason for the extinction of dinosaurs is still unclear, and I believe that the mystery of the demise of dinosaur families will be solved one day.

For nearly half a century, scientists have accumulated some data on the biological characteristics of dinosaurs.

Dinosaur's limbs (especially belts) are similar to those of mammals (that is, they stand upright under their bodies and can walk or run "strutting" on the ground. Dinosaurs of average 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 ~ 4 km/h, the running speed of larger dinosaurs can reach 15 ~ 2 km/h, and the slowest one is only 3.5 km/h.

Most dinosaurs were herbivores, and they ate a lot. sauropods weighing several tons to dozens of tons ate more than 1 kilograms a day, even more than one ton. There were few kinds and numbers of carnivorous dinosaurs. According to statistics, only 3 ~ 5 of every 1 dinosaurs were carnivorous dinosaurs.

dinosaurs are oviparous animals, and a few of them may be oviparous. During the reproductive period, males often fight for females or seduce their spouses with euphemistic guttural sounds. Eggs are 8 ~ 3mm 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 to be carefully cared for and fed by the mother for a period of time before they can live independently (for example, duckbilled dragons are also called "Cimu dragons"). Dinosaurs usually live for several years to several decades, and a few can live for as long as a hundred years.

Scientists usually think that dinosaurs are "warm animals", but now some scholars think that some dinosaurs may be "constant temperature." Barker, a famous American vertebrate paleontology scientist, thinks that the energy conversion rate of warm-blooded animals is low, and there are few Haversian blood vessels, which are the exchange place of calcium and phosphorus in bones, while the bones of warm-blooded animals are rich in 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 had a "thermostat". When dinosaurs walked and ran, they usually relied on the long tail, long neck, bone plate on the body surface, enlarged nasal passages and large venous sinuses in the brain to dissipate heat.

Dinosaurs have scales on their body surfaces, and some may have feathers or hairy skin derivatives, which may be as rich in 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 patterns.

Many people think that dinosaurs are huge and terrible animals, which is not comprehensive. Some dinosaurs are really big (the dragon body is 42.67 meters long), but some dinosaurs are similar in size to chickens.

Based on various studies, the characteristics of dinosaurs can be described as follows:

The belt has a socket, and ⅱ ~ Ⅶ vertebrae are healed; Four feet or two feet stand upright under the body, walking on the ground with the phalanges, and there are 3 ~ 5 claws or hooves at the toes; Rough skin, covered with scales or bone armor; It is a warm-blooded animal, oviparous (a few may be oviparous); Most of them have teeth, mostly phytophagous, and less carnivorous; The skull structure is similar to that of crocodiles.

References: Middle school biology

Running dinosaurs

After printing fossils, Alexander made a judgment that many large four-legged sauropods were really slow-moving "stupid", with a walking speed of only about 1 meter per second, which was similar to that of human walking. They walked on two feet. This is similar to the speed when humans walk fast. The footprints of the smaller bipedal dinosaurs weighing about 5 kilograms (similar to the size of a horse race) show that they can run at a speed of 12 meters per second, which has exceeded the highest speed of the human 1-meter race champion (11 meters per second), but it is still much lower than the running speed of the horse race (about 15 to 17 meters per second).

Chiropterus

Their bones were found in Europe. Pterodactylus was not very big, but its wings were only about 22 cm. However, Fengshen pterodactyl's wings were as long as 12 meters, as big as a bus. American scientists once found a pterodactyl, whose wings were more than 15 meters long. If we could see it today, we might think it was an airplane flying in the sky. Many flying pterodactyls were somewhat like bats today, and they seemed to use one hand. Having wings and claws has become a major feature of them. Some people think that later birds evolved from them.

Scientists have different understandings about how pterosaurs flew into the sky.

Some people think that those giant pterosaurs can't fly at all. They can't vibrate their wings like birds, but they can climb to high places first and spread their huge wings against the wind, so that they can use the updraft. Some people think that pterosaurs can flap their wings like birds because the membrane on their wings is very hard, and the bones and muscles on the outside of their wings are connected like a frame. Because their wings are very big, they can get a huge reaction force by flapping them a little, and make themselves fly.

Eel dragon

Eel dragon is a kind of plesiosaur, and their fossils have been found in Japan. After measurement, their fossils have been found. 8 meters. And they have sharp teeth.

Triceratops

Triceratops is a kind of ceratosaurus. It has a horn on its nose, like a rhinoceros, and two horns on its eyes, like a cow. These three horns are all 1 meter long, which is a powerful weapon for them to fight.

Lei Long

Lei Long is the largest dinosaur, and some of them are more than 3 meters long. It is as high as six stories. They are all herbivores or leaves. Most of the dinosaur fossils we saw in the museum are this kind of dinosaur.

Allosaurus

Allosaurus is a fierce and terrible carnivorous dinosaur. Its big mouth can swallow a pig at once. Its teeth are all bent inward. If the prey is bitten by it, it can't escape.

Data

Dinosaur _ _ _ _ _ _ The scene of the dinosaur era

Dinosaurs lived on the earth for 15 million years. During such a long time, the environment of the earth has also undergone many changes. The Pangu continent, which was originally connected as a whole, gradually drifted and split into the form we know now. After these landmasses drifted around the world, Coupled with climate change, the plant species on the earth have undergone tremendous changes. However, because these changes were gradually formed in a very long time, the animals that grew 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 landscape on the earth. Soon after, The first batch of flowering plants appeared, which greatly changed the plant landscape on the earth. Many plants and flowers that dinosaurs lived on at that time still exist on the earth today.

Dinosaurs

Carnivores

Carnivorous dinosaurs are large dinosaurs with large heads, powerful hind legs and short forelimbs. They all belong to theropod, and are often called carnivorous dragons or carnivorous lizards. Carnivorous dinosaurs walk on hind legs; Because their hind legs have to bear the weight of their huge bodies, they may not move very fast. Their heads are very big, their jaws are very long, and the whole row of huge curved teeth on their jawbones look like the serrations on the edge of steak knife. Carnivorous dinosaurs mainly feed on other dinosaurs, and sometimes they also eat animal carcasses. They may kill prey with their claws on their hind legs first, and then with the help of their teeth and claws on their forelimbs. Tear off the meat of the prey and eat it. Osteosaurus is also a carnivorous dinosaur, but they are completely different from ordinary carnivorous dinosaurs. Osteosaurus is light and agile, with a pair of long arms and palms that are easy to grab, and long and narrow jawbones. They run very fast and hunt down small mammals and insects. In addition, Osteosaurus often eats after large carnivorous dinosaurs are full. Pick up the leftovers and eat them.

Dinosaurs

Vegetarians

Many dinosaurs are herbivorous, including the largest sauropod dinosaur and all the birds and buttocks dinosaurs. In fact, it is much more troublesome for dinosaurs to eat plants than meat, because plants are made of cellulose and lignin, and these tough substances must be decomposed before they can be digested by the stomach. To solve this problem, herbivorous dinosaurs For example, sauropods don't chew at all, but directly swallow the food they have bitten into their stomachs, allowing bacteria in their stomachs to ferment the food or letting them deliberately eat pebbles to grind the food. Hadrosaurs dinosaurs have special teeth, so they can bite and grind the food first; Dinosaurs of the suborder Ceratosaurus tore up tough plants with exceptionally strong jawbones and sharp teeth.

Extinction of dinosaurs

What happened at the end of the Cretaceous period 65 million years ago, which caused dinosaurs and a large number of other creatures to die, scientists have been arguing endlessly. Some say that there was a geological orogeny on the earth at that time, because many mountains grew on the flat land, and the swamp was reduced. The climate has also become less humid and warm. The respiratory organs of dinosaurs can't adapt to the dry, cold and dry air, and in winter, dinosaurs run out of food, so they are on a blind alley. Some say that the supernova explosion caused a strong change in the earth's climate, and the temperature suddenly rose and then dropped very low. Others say that dinosaurs ate a lot of flowering plants, which contained a lot of toxins, and dinosaurs ate a lot. So he died of poisoning. The evidence is that flowering plants began to appear at that time. Others ingeniously said that it was because dinosaurs, a huge animal, ate too much and farted constantly, releasing a lot of methane gas into the air. Because of their too many numbers and long survival time, they destroyed the ozone layer of the earth and caused a devastating climate. Some even said that it was the result of aliens coming to the earth to hunt. Because they think dinosaur meat is particularly delicious. The evidence is that the dinosaur bone fossils they found in the Arctic have traces of being cut by laser. In short, they are all kinds and wonders. However, it is generally recognized by everyone that the meteorite impact theory.

_ _ In 198, American scientists found high concentration of iridium in the strata 65 million years ago, and its content was dozens or even hundreds of times higher than the normal content. Therefore, scientists have linked it to the extinction of dinosaurs. According to the iridium content, it is also inferred that the impact object is equivalent to an asteroid with a diameter of 1 kilometers. So