Since 1970s, many studies have pointed out that modern birds are probably the direct descendants of theropod dinosaurs. Most scientists regard birds as the only dinosaurs that have survived and developed to this day, and a few even advocate that they be classified into the same category.
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 main evolutionary branches of reptiles, which first appeared in the late Permian and became the dominant groups of amphibians in the middle Triassic.
Dinosaurs (excluding birds) are a main group of dragon reptiles living on land. Their limbs stand upright under their bodies instead of extending to their sides. [3] Many prehistoric reptiles are often informally identified as dinosaurs by the general public, such as pterosaurs, ichthyosaurs, plesiosaurs, black dragon and Panlong (Allosaurus and pterosaurs), but from a scientific point of view, these are not dinosaurs.
According to the latest research by some scientists, when the asteroid collided with the earth 66 million years ago, it was at a time when the dinosaur ecosystem was relatively fragile, and the environment changed dramatically because of the asteroid collision, and the "unlucky" dinosaurs became extinct.
Chinese name: dinosaur dragon
Latin scientific name: dinosaur, dinosaur
Field: animal kingdom
Portal: Chordata (Chordata)
Subdivision: Vertebrates (Vertebrates)
Class: Reptiles
Subclass: Diptera.
Lower door: lower jaw.
Superclass; quadruped
Lower class: Zulongopoda, the main dragon-shaped lower class.
Preface: dinosaur order, the head order of dinosaurs.
fossil
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The discovery of dinosaur fossils has a long history. Long before the discovery of dinosaurs, Europeans knew that there were many grotesque huge bone fossils buried underground. It was not until the paleontologist Mantel discovered dinosaurs and compared them with iguanas that the scientific community initially determined that they were a group of reptiles similar to lizards but long extinct.
Dinosaurs in Documentary
Dinosaurs in Documentary (34 photos)
Without the help of fossils, human beings would know nothing about the mysterious dinosaur species. So the study of dinosaurs is also the study of dinosaur fossils. Dinosaur fossils can be roughly divided into skeletal fossils and scar fossils, which are mainly preserved in sedimentary rocks formed in Mesozoic. The formation of dinosaur fossils is a complex, long and mysterious process, which involves the death and extinction of dinosaurs and is closely related to the changes of the earth over hundreds of millions of years. Its discovery and excavation are equally difficult. Scientists look for clues of dinosaur fossils through various means, and use modern high-tech means to restore fossils and study dinosaurs. Through their work, we gradually learned about the appearance and life habits of dinosaurs. The new discoveries and new ideas about dinosaurs from all over the world have repeatedly revised our original impression of dinosaurs and made them closer to the truth.
According to legend, dinosaur fossils of the Jin Dynasty were found in Zigong City, Sichuan Province, China. 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 people didn't know their exact attribution at that time, 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 at the University of Reading announced that he had finally found the following research results: 1677, an Englishman named Prut Gallon wrote a book about the natural history of Oxford.
Omnivorous dinosaur
Omnivorous dinosaurs (20 photos)
Books. In this book, prout Gallon describes a huge fossil thigh bone found in a quarry in the parish of Karovilla. 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.
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 described 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 145 years earlier than the first named dinosaur Iguanodon discovered in Mantels. Therefore, Hastert thinks that prout-Garonne Province should be the first discoverer and recorder of dinosaur fossils.
1842, British paleontologist richard 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 dinosaur fossils 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. There are at least 650 to 800 genera of dinosaurs described in the world. Later, scholars in Japan, China 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.
2 living environment
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Dinosaurs first appeared in the late Triassic about 225 million years ago, and died in the Cretaceous extinction event that occurred in the late Cretaceous about 65 million years ago.
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. Pangu continent, which was originally connected as a whole, gradually drifted and split into familiar forms. 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, because the climate became dry and cold, deserts appeared on the earth.
3 morphological characteristics
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Skeletal characteristics
The dinosaur bones have some evolutionary adaptations, which can be distinguished from the original ancestors of the main dragon. In the late dinosaur period, these characteristics experienced more evolutionary changes.
The * * * features of dinosaurs include:
The humerus has a low triangular crest (where the sternocleidomastoid muscle is attached), which is about 1/3 ~ 1/2 of the humerus.
There is a protruding block behind the intestinal bone.
The distal edge of the tibia is wide and has a backward flange.
The talus has obvious protuberance, which is consistent with the tibia.
In addition to the above characteristics, most dinosaurs have some * * * same characteristics, but they do not exist in other main dragons or early dinosaurs, so they are not classified as dinosaurs. Dinosaurs walked upright, similar to most modern mammals, while most other reptiles walked with their limbs extended to both sides. The buttock fossa of dinosaur faces to both sides, and the fourth largest trochanter of femur faces to the inside, and the two fit together to produce an upright gait.
Somatotype characteristics
Dinosaurs as a whole are very big. According to dinosaur standards, lizard's foot is one of the behemoths. In the long dinosaur era, even the smallest sauropods were larger than other animals in their habitats, while the largest sauropods were several grades larger than any animals that appeared on the surface.
Most dinosaurs were much smaller than large sauropods. The existing evidence shows that the average size of dinosaurs changed constantly in Triassic, Early Jurassic, Late Jurassic and Cretaceous. Most theropod dinosaurs weighed between 100 and 1000 kg, while most Holocene carnivores weighed between 10 and 100 kg. The estimated weight of dinosaurs is mostly between 1 and 10 metric tons. A study by the National Museum of Natural History in London pointed out that the average weight of dinosaurs was about 100 kg, while the average weight of new generation mammals was between 2 and 5 kg.
Judging from the existing intact bones, the tallest and heaviest dinosaur is Giraffatitan brancai (formerly known as Brachiosaurus). The fossil of long-necked dragon was found in Tanzania from 1907 to 19 12. A skeleton model composed of several individuals of similar size is now on display at the Humboldt Museum in Berlin. The model is 12 m high and 22.5 m long, and the estimated live weight is between 30 and 60 metric tons. The longest dinosaur is Liang Long, which is 27 meters long. It was discovered in Wyoming, USA on 1907 and is now on display at Carnegie Museum of Natural History in Pittsburgh, Pennsylvania.
main distinction
Ceratosaurus dinosaur photo album
Ceratosaurus dinosaur photo album (22 photos)
The biggest difference between dinosaurs and other reptiles lies in the posture of standing and the way of marching. Dinosaurs are completely upright, with their limbs directly under their bodies. This structure has more advantages than other reptiles (such as crocodiles, whose limbs extend outward) when walking and running. According to the different structural characteristics of dinosaur belts, they can be divided into two categories: sauropods and ornithosaurs. The main difference between them lies in their belt structure.
The pubic bone of most sauropods protrudes forward, while each pubic bone of ornithopods leans backward. In addition to the different hip structures, the life and behavior characteristics of these two dinosaurs are also different. Sauropods include herbivorous sauropods that walk on all fours, and carnivorous theropods that walk almost on all fours.
The belt of sauropod is three-gun-shaped when viewed from the side, with the pubic bone extending forward under the intestinal bone and the ischium extending backward, similar to lizard.
The waistband of ornithischia expands greatly in the front and back of the intestinal bone, and there is a large pubic protrusion on the front side of the pubic bone, which extends below the intestinal bone, and the back side extends parallel to the ischium to the front and bottom of the intestinal bone. So the pelvis is radiant from the side (there are other differences).
dinosaur
dinosaur
Sauropod dinosaurs mainly lived in Jurassic and Cretaceous, mostly large vegetarian dinosaurs. Small head, long neck, long tail and small teeth in spoon shape. The famous representative of sauropod is Mamenxilong, which was produced in Sichuan and Gansu provinces of China in the late Jurassic. It consists of 19 cervical vertebrae, and its neck length is about half of its body length. It is the largest known animal in the world-the fragile double-chambered dragon.
Theropod dinosaurs lived from the Late Triassic to the Cretaceous. They are all carnivorous dragons, walking on two feet, with sharp claws on their toes and well-developed heads, and they are the smartest one. Tyrannosaurus rex is a famous representative with teeth as sharp as daggers or knives in its mouth. Others, such as Allosaurus, Southern Dragon and Spinosaurus, are also quite famous.
4 species classification
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Dinosaur fossil
Dinosaur fossil
There are about 1000 kinds of dinosaurs living on the earth, but the age of dinosaurs is too far away from us, and we can only understand them through the fossils that have been discovered. Hundreds of species of dinosaurs were discovered. With the continuous progress of dinosaur research, the types of dinosaurs we know will continue to increase.
According to the different hip structures, all dinosaurs can be divided into two categories: sauropods and ornithopods. These two categories can be subdivided into smaller categories, up to the level of family.
Sauropods
Sauropods are divided into sauropods and theropods, and sauropods are divided into protosauropods and sauropods.
Primitive sauropods mainly lived from the Late Triassic to the Early Jurassic, and were medium-sized omnivorous and vegetarian dinosaurs, such as Ban Long, the first giant dinosaur living on the earth, and Ankylosaurus living in the Early Jurassic.
ornithischia
The suborder ornithopoda can be divided into five categories: ornithopoda, stegosaurus, Ankylosaurus, Ceratosaurus and pachycephala.
Ornithopoda is a group with the most fossils in ornithopoda and even the whole dinosaur category. They walk on two or four feet. The mandible has a single anterior tooth bone, and the teeth only grow on the cheeks. The crowns of the maxillary teeth bend inward and the crowns of the mandibular teeth bend outward. They lived from Late Triassic to Cretaceous, and they were all vegetarian dinosaurs. Such as: hadrosaurs, Iguanodons, etc.
Stegosaurus and Ankylosaurus
Stegosaurus and Ankylosaurus (16 photos)
Stegosaurus was a quadruped with an upright bone plate on its back and two or more pairs of bony spines on its tail. It mainly lived from Jurassic to early Cretaceous, and was the first large extinct dinosaur group. Its representatives are Stegosaurus and Kenterosaurus. The former is thought to live in the plain, while the latter is found in Tanzania.
Ankylosaurus was short and strong, covered with a bony deck, and mainly ate plants in the early Cretaceous.
Ceratosaurus is a four-legged vegetarian dinosaur. The back of the skull expanded into a cervical shield, most of which lived in the late Cretaceous. The parrot-billed dragon found in northern China belongs to the ancestor type of Ceratosaurus.
The main characteristics of pachycephalosaurus are that the skull is swollen and thick, the hole is closed, and the pubic bone in the disc is rejected by the ischium, which does not participate in the formation of the band. It mainly lived in Cretaceous.
Whether sauropods or birds, their belts leave a small hole between the intestine, ischium and pubis, which other reptiles do not have. It is this hole that shows that these two animals, called dinosaurs, are the closest relatives compared with all other reptiles.