The reason why dinosaurs are particularly impressive reptiles is that most dinosaurs have huge bodies, some of which are 20-30 meters long and weigh 40-50 tons. In fact, dinosaurs were not that big, and some were still very small. However, those small ones have been ignored. When it comes to dinosaurs, people will think of those huge and terrible images.
Jurassic is the heyday of dinosaurs, and the dinosaurs that appeared and began to develop in Triassic have quickly become the rulers of the earth. All kinds of dinosaurs came together to form a world of dragons with different shapes. At that time, besides Lei Long and Liang Long having huge bodies on land, ichthyosaurs and pterosaurs flying in the water also had great development and evolution.
Reptile (or reptile) is a kind of amniotic animal, belonging to quadrupeds and classified into different categories. The newer name is sauropod. The existing reptiles include 4 orders, and crocodiles include 23 species such as crocodiles, alligators, alligators and caimans.
Reptiles are the earliest vertebrates that really got rid of the dependence on water and conquered the land, and can adapt to various land living environments. Reptiles have also ruled the land for the longest time. The Mesozoic, when they ruled the earth, was also the most striking era in the whole biological history of the earth. At that time, reptiles not only ruled the land, but also ruled the ocean and sky. No other creature on earth has such a glorious history. Although it is no longer the era of reptiles, most reptiles have been extinct, and only a few have survived, but in terms of species, reptiles are still a very prosperous group, second only to birds and terrestrial vertebrates. It's hard to say how many kinds of reptiles there are now. There may be thousands of different statistics, and new species are still being identified. Generally speaking, there should be nearly 8,000 kinds of reptiles now. Because of getting rid of the dependence on water, the distribution of reptiles is greatly affected by temperature and less affected by humidity. The existing reptiles are distributed except Antarctica, most of which are distributed in tropical and subtropical regions, and few in temperate and frigid regions. Only a few species can reach the Arctic Circle or distribute in the mountains, while in the tropics, there are abundant species in both wet and dry areas.
Forest lizard
The earliest reptile of forest lizard appeared in the late Carboniferous, and evolved from the middle-toothed reptile about 320 million to 365.438 billion years ago. Forest lizard is the oldest known reptile, about 20~30 cm long, and its fossils are found in Nova Scotia, Canada. Xiluoxian lizard was once considered as the earliest reptile, but now it is considered to be closer to amphibians than amniotic animals. Oil shale lizards and middle dragons are the earliest reptiles. The earliest reptiles lived in the swamp forest in the late Carboniferous, but their size was smaller than that of the same period, such as raw water scorpions. The Little Ice Age at the end of Carboniferous gave early reptiles a chance to grow to a larger size.
Shortly after the first reptile appeared, two branches of evolution appeared, one of which was the imperforate subclass. The skull of imperforate subclass is hard and has no temporal holes, only holes corresponding to nostrils, eyes and spine. Turtles are considered as the only remaining imperforate animals because they have the same characteristics as skulls; Recently, however, some scientists believe that turtles are atavism and will be inherited to their original state to increase their protection ability.
lizard
Another branch of evolution is Diptera, which has two temporal holes in the skull, located behind the eyes. Diptera is further divided into two branches: ① Scallops include modern lizards, snakes, beaked lizards, and possibly marine reptiles extinct in Mesozoic; The main dragons include modern crocodiles and birds, as well as extinct pterosaurs and dinosaurs.
The earliest amniotic animals with hard skulls also evolved into another independent evolutionary branch called Monoforamina. There is a 1 fovea behind the eyes of closed arch animals, which can reduce the weight of skull, provide the attachment point of jaw muscles and increase the bite force. The monotremes eventually evolved into mammals, so they are called mammal-like reptiles. Monoforaminifera used to be a subclass of reptiles, but now it is an individual sympodial class.
At the end of Carboniferous, amphibians and reptiles became the dominant animals on land. Spinosaurus and reptiles still lived near the water, while amphibians first evolved into larger bodies, such as pterosaurs and Allosaurus. In the middle Permian, the climate changed many times, which led to changes in the ecosystem, and theropoda replaced Panlong as the dominant animal on land.
Foraminiferal reptiles flourished in Permian. Among them, the sawtooth dragon also evolved into a larger body. Most non-porous reptiles were extinct in the Permian-Triassic extinction event, and turtles may be their descendants.
pterosaur
During the Permian period, petaloid reptiles did not flourish and were small in size. But at the end of Permian, two evolutionary branches evolved: the lower layer of the main dragon and the lower layer of the scale dragon, and finally most of the existing reptiles evolved.
The Permian-Triassic extinction event at the end of Permian led to the mass extinction of amphibians and toothless reptiles, and the main dragon suborder became the dominant animal on land. The early main dragon had an upright quadruped gait, and many evolutionary branches evolved in a short time: dinosaurs, pterodactyls, alligators, Superorders and other Triassic main dragons. Among them, dinosaurs were the main terrestrial animals from Late Triassic to Late Cretaceous. Therefore, the Mesozoic era is sometimes dubbed the "dinosaur era" and "reptile era". In the middle Jurassic, theropod dinosaurs evolved many feathered dinosaurs and further evolved birds.
snake
Compared with the main dragon suborder, Squamous suborder may evolve into many groups of marine reptiles: Squamous suborder, Leo suborder, plesiosaur suborder, black dragon suborder; Ichthyosaurs may have evolved from more primitive bipedal reptiles. Various small terrestrial reptiles, such as beaked lizards, lizards, snakes and earthworm lizards, also evolved from Lepidoptera.
Under the competitive pressure of dinosaurs, theropoda evolved into a species with small size and high metabolic rate, and evolved into a mammal in the late Jurassic.
The extinction event at the end of Cretaceous made dinosaurs, pterosaurs, most marine reptiles and most crocodiles extinct, while birds and mammals flourished and diversified again in the Cenozoic, so the Cenozoic was dubbed the "Mammalian Age". Only turtles, beaked lizards, lizards, snakes, earthworm lizards and crocodiles have survived to modern times, mainly distributed in tropical and subtropical regions. There are about 8200 kinds of reptiles, half of which belong to snakes.