According to traditional belief, it is believed that after amphibians evolved into reptiles, one tribe evolved into mammals and the other evolved into birds, but this division method has long been outdated. In fact, the ancestors of mammals, as well as reptiles and birds, separated more than 300 million years ago in the late Carboniferous period. In the late Carboniferous period, two amphibians simultaneously evolved amniotic membranes and began to adapt to terrestrial life.
There used to be a term called "mammal-like reptiles (subclass inferior/single-hole subclass)", but now it is gradually eliminated, and it is uniformly called the homotophea (mammals), which contains all mammals and their ancestors, and "hegong" refers to "fixed zygomatic arch". The zygomatic arch is a very special part, and many people will think that it represents the height of the front of the cheekbone side, but it is actually wrong. It is actually a lateral area under the eye socket of the face. Since there is a lower temporal hole (temple) on each side of the skull, a fixed zygomatic arch is ensured (there is only a pair of zygomatic arches under a pair of temporal foramen, and is not divided by two pairs of temporal foramen into two zygomatic arches on each side, as in the lizard order). Another important feature of the hydylopods is that all four legs are under the trunk rather than on the sides.
Temporal foramen and zygomatic arches of the order Zygophyllum and Lizards
Zygomatic arch and zygomatic protrusion
Correspondingly, birds and reptiles in the traditional sense are classified in the order Lizards (dragons). This class of amniotics does not have a zygomatic arch that is integrated, and the limbs are usually grown on the sides of the torso, so it is easier to walk upright than the zygomatic arch.
Giant arthropods became extinct after the Carboniferous rainforest collapse event 307 million years ago, and the dry climate since then has diminished the advantages of the mistic class over amniotics.
In the Paleozoic, the hygnepines gained the upper hand in competition with the sauropods. This is due to the fact that in the late Carboniferous period, the homoaptopods were the first to achieve large-scale, and the first to evolve a curved spine, which increased the ability to move by a notch. As the earliest group of arches, the order Panlong has evolved the dorsal sail (a sail composed of long nerve spines), as a semi-circular giant dorsal sail with a long back, which has both armored protective effects and a certain range of body temperature regulation functions, and after the evolution into the theropod, a considerable number of species have evolved into thermostatic animals.
The Archaeopteryx, which lived 306 million years ago, is one of the earliest known species of Zygoidon, with a length of about 50 cm.
The plesiosaurs, who lived at the end of the Carboniferous period, were more than 3 meters long and may have been covered with scales during their lifetime.
Kirones began to appear at the end of the Carboniferous period
Haputo beasts, which began to appear in the last stage of the Carboniferous Period, were at least 1.5 meters long and fed on insects and other small vertebrates.
Heterodontosaurus of the family Cuneiosaurus, which lived in the early Permian, was about 3.5 meters long and was the land overlord of the time.
After the middle of the Permian, the order Theropod reached unprecedented prosperity and radiation diversification and gradually replaced the order Panlong. Temporal foramen in the order Theoremosaurus is usually larger than that of Theronosaurus. The jaw is complex and strong. The teeth have been specialized out of the front of the bite with the incisors, with the punctures and tears of the back with canine teeth, and the rear of the chewing molars. The beast hole class also often abandons the back sail of the ancestor Panlong, after all, the bulky sail back is also a burden of a weak rib nature, and once it is broken, it is either dead or disabled.
An internal evolutionary branch of theropods
As the most primitive theropod, the Bamo crocodile has slender limbs and large holes behind the eyes (unlike the small holes of other primitive pyllids), so the bite force of the Bamo crocodile may be small, and its body length can reach 1.5 to 2 meters. They are medium-sized, light carnivores that evolved between the cuneiformes of the order Panlongosaurus and the more advanced euthanopheae.
The Balmo crocodile of Russia that lived in the middle of the Permian
Later dinosaurs dominated in the middle of the Permian, and all dinosaurs had the feature of interlacing their upper and lower incisors when biting, and most dinosaurs evolved thickened skulls. These include the largest herbivorous mammals (tapirs), omnivorous mammals (alligators) and carnivorous mammals (Antio beasts), the former of which can grow to about 4.5 meters long and weigh up to 2 metric tons, while the latter can be more than 5 meters long but weigh only about 500-600 kg. After the Emei Mountain Basalt Eruption Event (the late Guadeloupe extinction event) at the turn of the middle and late Permian, the dinosaurs became extinct and replaced their original niches with more advanced neo-mammals.
Tapir-headed beast
Great crocodile
Antio Beast
" Plesiosaurus " is a plant-eater with a slender tail and a smaller body. Diodonts are large plant-eating mammals with short, bulky bodies, bucket waists, and strong limbs, and the temporal foramen behind their skulls become larger to accommodate larger jaw muscles, and when the mouth is closed, the jaw is closed to produce a strong cutting action, so that the two-toothed beasts can handle hard terrestrial plants.
A shrew-limbed beast of the Benosaurus
Diplodonts
By the late Permian, the toothed beasts, theropods, and canines flourished on various continents as the three most evolved theropods. Among them, the reeds are extremely fierce predators, initially only the size of a dog, and after millions of years, they evolved into a huge 4.5-meter-long carnivorous wolf lizard. The therocephalus and the suborder Canis as euthnodonts have secondary jaws (partitions separating breathing and digestive pathways in the mouth), no posterior orbital rods, and the phalanges have been reduced to a mammal-like form, and some of their types have evolved into true thermostatics, of which canines are the ancestors of modern mammals. There is no clear boundary between cold-blooded animals and warm-blooded animals, such as swordfish, golden spears, fish rat sharks and leatherback turtles belong to medium-temperature animals, which can regulate the temperature within a certain range by burning in vivo chemistry, but they cannot maintain an absolutely constant body temperature, which is the transition link from cold-blooded animals to warm-blooded animals. Evolution into thermostatic animals is a general trend under the convergence and evolution of different species, in addition to birds and mammals, reptiles in the Taiga lizard, fish in the moonfish are warm-blooded animals, crocodile ancestors in the Triassic period is also warm-blooded animals but later degenerated. The sail-backed Panosaurus is actually a mesophobic animal, and by therocenes and canines, some of the more advanced species have converged and evolved into warm-blooded animals in the modern sense.
The wolf-lizard beasts of the Lisodons prey on Ankylosaurus
The therocephate was a predator of South Africa from the late Permian to the early Triassic
Bao's is a typical advanced herbivorous head
Karenites are a polygamously developed canine-toothed theropod that may be aquatic for preying on small fish or insects
The therocephalus, with its raised ridges in the nasal cavity, is thought to have been the first theropod to evolve a thermostatic function.
The Devina beast, which lived in Late Permian Russia, was a small omnivorous cynodont with small incisors, 2 canine teeth, and 10 to 14 molars.
Cynodonts first appeared in the late Permian period, had a full secondary jaw, could breathe when eating, had a broad snout, and had erect limbs.
For the panosaurs and theropods, it is difficult to tell from the fossils alone whether they have evolved breast and fetal functions similar to those of modern mammals.
The situation of the lizards in the Paleozoic Era cannot be compared with the Azymosaurus, which is far less prosperous than the latter, and the fossil remains are not very rich, and most of them are small.
The forest lizard of the late Carboniferous period 312 million years ago was the earliest known member of the lizard order, about 20 cm long, with small teeth, and fed on insects.
The macronospermosaur family is a small, lizard-like reptile that lived from the Late Carboniferous to the Permian.
An internal evolutionary branch of the lizard order
Paraptus reptiles refer to the most primitive reptiles that retain more primitive features, such as a strong, low-hanging body and a large humerus on the posterior side of the skull, and although they also have two openings in the posterior part of the skull, the temporal temporal foramen of the subreptile are generally more conserved and are therefore considered equivalent to the absence of temporal temporal foramen (i.e., aperture suborder). Current genetic and molecular studies have shown that turtles and tortoises, although without temporal temporal foramen, are likely to have lost temporal temporal foramen during evolution, and turtles are closer to the main dragons in terms of kinship, while sub-reptiles are all extinct today. True reptiles with temporal holes became the backbone of today's reptiles.
According to the existing research, the proto-paleolithic lizard family, including the forest lizard, which appeared in the late Carboniferous Period, although the skull did not have holes and resembled modern turtles, was more closely related to true reptiles. The sub-reptiles that can be identified in the late Carboniferous period are mainly Erpetonyx, which appeared more than 303 million years ago, and Mesquiteratosaurs, which lived in the late Carboniferous and early Permian periods.
Fossil of Erpetonyx
Erpetonyx hypothetical, it may be carnivorous, may have a variety of skeletal features, slender body, with large claws and strong tendon attachment points.
Fossils of The Middle Dragon as evidence for the plate drift theory
The middle dragon is about 1 meter long and its slender beak is suitable for fishing in salt lakes
Paraptiles flourished much more than true reptiles during the Permian period, and the order Prescenadiformes was an important evolutionary branch of paraptiles that appeared in the Middle Permian, and they included a diverse range of animals, including small, lizard-like pre-dipsiosaurs, as well as large, thickly armored herbivores, serrated dragons.
The orchid crocodile is about 75 cm long and is an iconic paraptile of the Permian period.
With thick armor, the sawtooth dragon can reach more than 3 meters long and weigh more than 600 kilograms.
True reptiles diverged into the two main trunks of the main order, the main order of the lower order of the plesiosaur and the lower order of the lepidosaur. The difference between the two is that the lepidontosaurs are incomplete, the main plesiosaur skull retains a complete double temporal hole; the lepidontosaur terminal teeth (beaked lizard) or lateral teeth (lizards and snakes), the main lepidosaurs have grooved teeth (including early birds); the main plesiosaurs have maxillary foramen (anterior orbital foramen, that is, a pair of holes between the eye sockets and nostrils on both sides of the skull), the lepidosaurs do not; the limbs of the lepidosaurs are located on the outside of the body, and the spine swings from side to side during movement. The limbs of the main dragons are close to the body (dinosaurs and some Triassic main dragons have upright limbs directly below the body, the abdomen is far from the ground), and the spine remains straight during exercise; the main dragons have a higher degree of ventricular separation and can use the air sac and bronchial double breathing, the main dragon-shaped heart has four chambers, and the lepidosaur has only three chambers. Lepidoptera are basically cold-blooded, while the main dragons have a considerable proportion of warm-blooded animals. The main dragon-shaped class can be understood as the nobility within the lizard class.
Most of the true reptiles of the Permian period have not yet differentiated to the extent of lepidosaurs and main dragons, and the more representative ones are the Yang lizard, the empty-tailed lizard, and the Claudio lizard. The fossils of Lepidoptera and the main dragon of this period are very few, related to the situation in which the sauropods were suppressed by the whole of the plesiosaurs, the most primitive of the lepidosaurs appeared in the Late Permian (the current lack of complete fossils before the Triassic Period), and the representative of the main dragons was the prototylans that began to appear 260 million years ago. As the ancestor of various later dominant dragons, protodra was slender, resembling a lizard, with a long neck, limbs, and a length of about 2 meters, and its body shape showed that they could move quickly, and it was speculated that they mainly fed on insects. The paleocaenidae, once classified as the ancestors of dinosaurs, lived in Russia during the Changxing period of the late Permian period and the beginning of the Triassic. The body of the ancient crocodile family is about 1.5 meters long, and its limbs are short and stretched on both sides. As crocodile-like animals, they lack the hard scales of a real crocodile, and the characteristics of the skeleton are more primitive. Their most distinctive feature is that the anterior maxilla of the anterior part of the upper jaw protrudes significantly downwards and protrudes above the lower jaw. Such masterosaurs may have lived on animal carcasses, so these carrion-eating animals escaped the mass extinction event at the end of the Permian and rapidly radiated to evolve a rich variety of main dragons in the later Triassic.
Young's lizards prey on snails
An empty-tailed lizard that could glide in the late Permian
Half-seaborn Claudio lizard
Russian main dragon of the late Permian
Original dragon imagination diagram
Ancient crocodile in Russia at the end of the Permian
In general, although the Permian period still continued the supremacy of the large labyrinthic amphibians in the waters of the Carboniferous period, the Homophorae was also one of the main rulers of the Permian, and the Zygopoda dominated the major ecological niches of the Permian, and the only drawback was the failure to enter the ocean. In general, the lizards can only shrink in some remote corners, and the sense of existence left in the stratigraphic fossils is not very strong.