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Origin of reptiles

Origin of reptiles- one of the important issues in the theory of evolution, the process as a result of which the first animals belonging to the class Reptilia appeared.

Permian period

From the Upper Permian deposits of North America, Western Europe, Russia and China, remains of cotylosaurs are known ( Cotylosauria). In a number of characteristics they are still very close to stegocephals. Their skull was in the form of a solid bone box with openings only for the eyes, nostrils and parietal organ, the cervical spine was poorly formed (although there is a structure of the first two vertebrae characteristic of modern reptiles - atlanta And epistrophy), the sacrum had from 2 to 5 vertebrae; the cleithrum, a skin bone characteristic of fish, was preserved in the shoulder girdle; the limbs were short and widely spaced.

The further evolution of reptiles was determined by their variability due to the influence of various living conditions that they encountered during reproduction and settlement. Most groups became more mobile; their skeleton became lighter, but at the same time stronger. Reptiles consumed a more varied diet than amphibians. The technique of its extraction has changed. In this regard, the structure of the limbs has undergone significant changes, axial skeleton and skulls. For the majority, the limbs became longer, and the pelvis, gaining stability, was attached to two or more sacral vertebrae. The “fishy” bone, the cleithrum, has disappeared from the shoulder girdle. The solid shell of the skull has undergone partial reduction. In connection with the more differentiated muscles of the jaw apparatus, pits and bone bridges separating them appeared in the temporal region of the skull - arches that served to attach a complex system of muscles.

Synapsids

The main ancestral group that gave rise to all the diversity of modern and fossil reptiles were cotylosaurs, but the further development of reptiles followed different paths.

Diapsids

The next group to separate from the cotylosaurs were the Diapsida. Their skull has two temporal cavities, located above and below the postorbital bone. Diapsids at the end of the Paleozoic (Permian) gave an extremely broad adaptive radiation to systematic groups and species, which are found both among extinct forms and among living reptiles. Among diapsids, two main groups emerged: Lepidosauromorpha and Archosauromorpha. The most primitive diapsids from the group of Lepidosaurs are the order Eosuchia ( Eosuchia) - were the ancestors of the Beak-headed order, from which only one genus is currently preserved - hatteria.

At the end of the Permian, squamate (Squamata) separated from the primitive diapsids, becoming numerous in the Cretaceous period. By the end of the Cretaceous period, snakes evolved from lizards.

Origin of archosaurs

see also

• Temporal arches

Notes

Literature

• Naumov N.P., Kartashev N.N. Part 2. Reptiles, birds, mammals // Zoology of vertebrates. - M.: Higher School, 1979. - P. 272.

Wikimedia Foundation. 2010.

Carboniferous period

Seymouria

Anapsid group

Synapsid group.

Diapsid group

• Scaly;
• Turtles;
• Crocodiles;
• Beakheads.

hatteria,

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The body is divided into head, neck, torso, tail and five-fingered limbs.
The skin is dry, devoid of glands and covered with a horny covering that protects the body from drying out. The growth of the animal is accompanied by periodic molting.
The skeleton is strong and ossified. The spine consists of five sections: cervical, thoracic, lumbar, sacral and caudal. The shoulder and pelvic girdles of the limbs are strengthened and connected to the axial skeleton. The ribs and chest are developed.
The musculature is more differentiated than in amphibians. Developed cervical and intercostal muscles, subcutaneous muscles. The movements of the body parts are more varied and faster.
The digestive tract is longer than that of amphibians and is more clearly differentiated into sections. Food is captured by jaws with numerous sharp teeth. Walls oral cavity and the esophagus are equipped with powerful muscles that push large portions of food into the stomach. At the border of the small and large intestines there is a cecum, especially well developed in herbivorous land turtles.
The respiratory organs - the lungs - have a large respiratory surface due to their cellular structure. Developed airways - trachea, bronchi, in which the air is moistened and does not dry out the lungs. Ventilation of the lungs occurs by changing the volume chest.
The heart is three-chambered, but the ventricle has an incomplete longitudinal septum, which prevents complete mixing of arterial and venous blood. Most of the body of reptiles is supplied with mixed blood with a predominance of arterial blood, so the metabolic rate is higher than that of amphibians.

What animals did reptiles come from? When did the ancestors of reptiles live?

However, reptiles, like fish and amphibians, are poikilothermic (cold-blooded) animals, whose body temperature depends on the temperature of their environment.
The excretory organs are the pelvic kidneys. Urine flows through the ureters into the cloaca, and from it into the bladder. In it, water is additionally sucked into the blood capillaries and returned to the body, after which urine is excreted. Final product nitrogen metabolism, excreted in the urine - uric acid.
The brain has a larger relative size than that of amphibians. The cerebral hemispheres of the forebrain with the rudiments of the cortex and cerebellum are better developed. The forms of behavior of reptiles are more complex. Sense organs are better adapted to a terrestrial lifestyle.
Fertilization is only internal. Eggs, protected from drying out by a leathery or shelled shell, are laid by reptiles on land. The embryo in the egg develops in a watery shell. Development is direct.

Origin of reptiles

Pedigree of reptiles

About 300 million

years ago the first amphibians appeared on Earth. However, already at the end of this period and beyond, the climate became dry again, and the descendants of the first amphibians began to develop in two directions. Some remained near the water and turned into modern amphibians. Others, on the contrary, began to adapt to the dry climate and turned into reptiles.

What changes have they made? First of all, a dense shell appeared on the eggs, so that they could be laid on land. In addition, reptiles began to lay large eggs, with big amount yolk. The development of the embryo lengthened, but what began to hatch was not a helpless larva, but a fully formed animal, differing from an adult only in its smaller size, already fully adapted to living conditions on land.

Adult reptiles also acquired the changes necessary for life on land. They have developed dense, keratinized skin that prevents evaporation. Oxygen does not pass through such skin. Therefore, the lungs have changed: they have acquired a cellular structure, that is, their working surface has greatly increased. In addition, ribs appeared, a chest was formed, and the breathing process became active by expanding and contracting the chest. A septum has appeared in the ventricle of the heart, although it is not completely complete, so that part of the blood mixes in it. The separation of venous and arterial blood in reptiles is much more perfect than in amphibians. However, they remain cold-blooded animals, their body temperature depends on the temperature environment.

In the skeleton, along with the appearance of ribs, the cervical region greatly lengthened and the head became more mobile. When grasping prey, reptiles do not turn their whole body, as fish and amphibians do, but only turn their head. The senses have also improved. Of particular note is the improvement of the brain. Due to more varied movements, the cerebellum, which is responsible for the coordination of movements, has enlarged. The brain and sensory organs, as well as the behavior of reptiles, have a more complex structure compared to amphibians.

Ancient extinct reptiles - tyrannosaurus, tailed flying lizard, brontosaurus, ichthyosaur

The rise and extinction of ancient reptiles

So, reptiles became much more active and, not afraid to move away from the water, spread widely across the Earth. Gradually, many species emerged among them. The appearance of giant reptiles is especially characteristic of this time. Thus, some dinosaurs (“terrible lizards”) were up to 30 meters long and weighing up to 50 tons - the largest land vertebrates that ever existed on Earth. Such giants were even forced to return to a semi-aquatic lifestyle again - their mass decreases in water. They roamed shallow waters and fed on coastal and aquatic plants, reaching them with the help of a long neck. There were also predators then, also very large, up to 10 meters long. Some reptiles that lived at that time even completely returned to an aquatic lifestyle, although they did not lose pulmonary respiration. Such, for example, was an ichthyosaur, or fish lizard, very similar in shape to a modern dolphin. Finally, there were flying lizards - pterodactyls.

Thus, reptiles have mastered all habitats - land, water and air. They formed many species and became the dominant animals on Earth.

But 70-90 million years ago, the climate on most of the Earth changed dramatically and became cold. At the same time there were more various types warm-blooded mammals - competitors of reptiles. This led to the fact that most reptiles, primarily all giant forms, became extinct, since giants cannot hide in shelters for the winter. Few reptiles have survived to this day - turtles, crocodiles, lizards and snakes. By the way, among them the largest ones are found only in warm countries and lead an aquatic or semi-aquatic lifestyle.

Origin and evolution of reptiles. Brief characteristics of the main groups of fossil reptiles.

The appearance of reptiles on Earth - greatest event in evolution.

It had enormous consequences for all of nature. The origin of reptiles is one of the important questions in the theory of evolution, the process as a result of which the first animals belonging to the class Reptilia appeared. The first terrestrial vertebrates arose in the Devonian (more than 300 million years ago). These were armored-headed amphibians - stegocephalians. They were closely associated with bodies of water, since they reproduced only in water and lived near water. The development of spaces remote from bodies of water required a significant restructuring of the organization: adaptation to protecting the body from desiccation, breathing atmospheric oxygen, efficient movement on solid substrate, and the ability to reproduce outside of water. These are the main prerequisites for the emergence of a qualitatively different new group animals - reptiles. These changes were quite complex; for example, it required the development of powerful lungs and a change in the nature of the skin.

Carboniferous period

Seymouria

All reptiles can be divided into three groups:

1) anapsids - with a solid cranial shell (cotylosaurs and turtles);

2) synapsids - with one zygomatic arch (animal-like, plesiosaurs and, possibly, ichthyosaurs) and

3) diapsids - with two arches (all other reptiles).

Anapsid group is the oldest branch of reptiles that have many common features in their skull structure with fossil stegocephalians, since not only many of their early forms (cotylosaurs), but even some modern ones (some turtles) have a solid cranial shell. Turtles are the only living representatives of this ancient group of reptiles. They apparently separated directly from the cotylosaurs. Already in the Triassic, this ancient group was fully formed and, thanks to its extreme specialization, has survived to the present day, almost unchanged, although in the process of evolution, some groups of turtles switched several times from a terrestrial lifestyle to an aquatic one, and therefore they almost lost their bony shields , then acquired them again.

Synapsid group. Marine fossil reptiles - ichthyosaurs and plesiosaurs - separated from the group of cotylosaurs. Plesiosaurs (Plesiosauria), related to synaptosaurs, were marine reptiles. They had a wide, barrel-shaped, flattened body, two pairs of powerful limbs, modified into swimming fins, very long neck, ending in a small head, and a short tail. The skin was bare. Numerous sharp teeth sat in separate cells. The sizes of these animals varied over a very wide range: some species were only half a meter in length, but there were also giants that reached 15 m. while plesiosaurs, having adapted to aquatic life, still retained the appearance of terrestrial animals, ichthyosaurs (Ichthyosauria), belonging to ichthyopterygians, acquired similarities with fish and dolphins. The body of ichthyosaurs was spindle-shaped, the neck was not pronounced, the head was elongated, the tail had a large fin, and the limbs were in the form of short flippers, with the hind ones being much smaller than the front ones. The skin was bare, numerous sharp teeth (adapted to feeding on fish) sat in a common groove, there was only one zygomatic arch, but of an extremely unique structure. The sizes varied from 1 to 13 m.

Diapsid group includes two subclasses: lepidosaurs and archosaurs. The earliest (Upper Permian) and most primitive group of lepidosaurs is the order Eosuchia. They are still very poorly studied; the best known is lounginia - a small reptile with a lizard-like physique, with relatively weak limbs that had the usual reptilian structure. Its primitive features are expressed mainly in the structure of the skull; teeth are located both on the jaws and on the palate.

There are now about 7,000 species of reptiles.

Reptiles are... Reptiles: photos

that is, almost three times more than modern amphibians. Living reptiles are divided into 4 orders:

• Scaly;
• Turtles;
• Crocodiles;
• Beakheads.

The most numerous order of squamates (Squamata), including about 6,500 species, is the only currently thriving group of reptiles, widespread throughout the globe and making up the bulk of the reptiles of our fauna. This order includes lizards, chameleons, amphisbaenas and snakes.

Much fewer turtles(Chelonia) - about 230 species, represented in the animal world of our country by several species. This is a very ancient group of reptiles that has survived to this day thanks to a kind of protective device - the shell in which their body is encased.

Crocodiles (Crocodylia), of which about 20 species are known, inhabit continental and coastal waters of the tropics. They are direct descendants of ancient, highly organized reptiles of the Mesozoic.

The only species of modern rhynchocephalia, the tuatteria has many extremely primitive features and is preserved only in New Zealand and the adjacent small islands.

Reptiles have lost their dominant position on the planet mainly due to competition with birds and mammals against the background of a general cooling, which is confirmed by the current ratio of the number of species of different classes of terrestrial vertebrates. If the share of amphibians and reptiles that are most dependent on environmental temperature is quite high on a planetary scale (10.5 and 29.7%), then in the CIS, where the area of ​​warm regions is relatively small, they are only 2.6 and 11.0% .

Reptiles, or reptiles, of Belarus represent the northern “outpost” of this diverse class of vertebrate animals. Of the more than 6,500 species of reptiles now living on our planet, only 7 are represented in the republic.

In Belarus, which does not have a warm climate, there are only 1.8% of reptiles and 3.2% of amphibians. It is important to note that the decrease in the proportion of amphibians and reptiles in the fauna of northern latitudes occurs against the background of a decrease in the total number of species of terrestrial vertebrates. Moreover, out of four orders of modern reptiles, only two (turtles and squamates) live in the CIS and Belarus.

The Cretaceous period was marked by the collapse of reptiles and the almost complete extinction of dinosaurs. This phenomenon poses a mystery to science: how did a huge, thriving army of reptiles occupying all ecological niches, which had representatives from the tiniest creatures to unimaginable giants, so suddenly become extinct, leaving only relatively small animals?

It was these groups that at the beginning of the modern Cenozoic era occupied a dominant position in the animal world. And among reptiles, out of 16-17 orders that existed during their heyday, only 4 survived. Of these, one is represented by a single primitive species - hatteria, preserved only on two dozen islands near New Zealand.

The other two orders - turtles and crocodiles - unite a relatively small number of species - about 200 and 23, respectively. And only one order - squamates, which includes lizards and snakes, can be assessed as thriving in the current evolutionary era. This is a large and diverse group, numbering more than 6,000 species.

Reptiles are distributed throughout the globe, except Antarctica, but extremely unevenly. If their fauna is most diverse in the tropics (in some regions there are 150-200 species), then only a few species penetrate into high latitudes (in Western Europe only 12).

Origin and evolution of reptiles. Brief characteristics of the main groups of fossil reptiles.

The appearance of reptiles on Earth is the greatest event in evolution.

It had enormous consequences for all of nature. The origin of reptiles is one of the important questions in the theory of evolution, the process as a result of which the first animals belonging to the class Reptilia appeared. The first terrestrial vertebrates arose in the Devonian (more than 300 million years ago). These were armored-headed amphibians - stegocephalians. They were closely associated with bodies of water, since they reproduced only in water and lived near water. The development of spaces remote from bodies of water required a significant restructuring of the organization: adaptation to protecting the body from desiccation, breathing atmospheric oxygen, efficient movement on solid substrate, and the ability to reproduce outside of water. These are the main prerequisites for the emergence of a qualitatively different new group of animals - reptiles. These changes were quite complex; for example, it required the development of powerful lungs and a change in the nature of the skin.

Carboniferous period

Seymouria

All reptiles can be divided into three groups:

1) anapsids - with a solid cranial shell (cotylosaurs and turtles);

2) synapsids - with one zygomatic arch (animal-like, plesiosaurs and, possibly, ichthyosaurs) and

3) diapsids - with two arches (all other reptiles).

Anapsid group is the oldest branch of reptiles that have many common features in their skull structure with fossil stegocephalians, since not only many of their early forms (cotylosaurs), but even some modern ones (some turtles) have a solid cranial shell. Turtles are the only living representatives of this ancient group of reptiles. They apparently separated directly from the cotylosaurs. Already in the Triassic, this ancient group was fully formed and, thanks to its extreme specialization, has survived to the present day, almost unchanged, although in the process of evolution, some groups of turtles switched several times from a terrestrial lifestyle to an aquatic one, and therefore they almost lost their bony shields , then acquired them again.

Synapsid group. Marine fossil reptiles - ichthyosaurs and plesiosaurs - separated from the group of cotylosaurs. Plesiosaurs (Plesiosauria), related to synaptosaurs, were marine reptiles. They had a wide, barrel-shaped, flattened body, two pairs of powerful limbs modified into swimming flippers, a very long neck ending in a small head, and a short tail. The skin was bare. Numerous sharp teeth sat in separate cells. The sizes of these animals varied over a very wide range: some species were only half a meter in length, but there were also giants that reached 15 m.

Origin of reptiles

IN while plesiosaurs, having adapted to aquatic life, still retained the appearance of terrestrial animals, ichthyosaurs (Ichthyosauria), belonging to ichthyopterygians, acquired similarities with fish and dolphins. The body of ichthyosaurs was spindle-shaped, the neck was not pronounced, the head was elongated, the tail had a large fin, and the limbs were in the form of short flippers, with the hind ones being much smaller than the front ones. The skin was bare, numerous sharp teeth (adapted to feeding on fish) sat in a common groove, there was only one zygomatic arch, but of an extremely unique structure. The sizes varied from 1 to 13 m.

Diapsid group includes two subclasses: lepidosaurs and archosaurs. The earliest (Upper Permian) and most primitive group of lepidosaurs is the order Eosuchia. They are still very poorly studied; the best known is lounginia - a small reptile with a lizard-like physique, with relatively weak limbs that had the usual reptilian structure. Its primitive features are expressed mainly in the structure of the skull; teeth are located both on the jaws and on the palate.

There are now about 7,000 species of reptiles, almost three times as many as modern amphibians. Living reptiles are divided into 4 orders:

• Scaly;
• Turtles;
• Crocodiles;
• Beakheads.

The most numerous order of squamates (Squamata), including about 6,500 species, is the only currently thriving group of reptiles, widespread throughout the globe and making up the bulk of the reptiles of our fauna. This order includes lizards, chameleons, amphisbaenas and snakes.

There are significantly fewer turtles (Chelonia) - about 230 species, represented in the animal world of our country by several species. This is a very ancient group of reptiles that has survived to this day thanks to a kind of protective device - the shell in which their body is encased.

Crocodiles (Crocodylia), of which about 20 species are known, inhabit continental and coastal waters of the tropics. They are direct descendants of ancient, highly organized reptiles of the Mesozoic.

The only species of modern rhynchocephalia, the tuatteria has many extremely primitive features and is preserved only in New Zealand and the adjacent small islands.

Reptiles have lost their dominant position on the planet mainly due to competition with birds and mammals against the background of a general cooling, which is confirmed by the current ratio of the number of species of different classes of terrestrial vertebrates. If the share of amphibians and reptiles that are most dependent on environmental temperature is quite high on a planetary scale (10.5 and 29.7%), then in the CIS, where the area of ​​warm regions is relatively small, they are only 2.6 and 11.0% .

Reptiles, or reptiles, of Belarus represent the northern “outpost” of this diverse class of vertebrate animals. Of the more than 6,500 species of reptiles now living on our planet, only 7 are represented in the republic.

In Belarus, which does not have a warm climate, there are only 1.8% of reptiles and 3.2% of amphibians. It is important to note that the decrease in the proportion of amphibians and reptiles in the fauna of northern latitudes occurs against the background of a decrease in the total number of species of terrestrial vertebrates. Moreover, out of four orders of modern reptiles, only two (turtles and squamates) live in the CIS and Belarus.

The Cretaceous period was marked by the collapse of reptiles and the almost complete extinction of dinosaurs. This phenomenon poses a mystery to science: how did a huge, thriving army of reptiles occupying all ecological niches, which had representatives from the tiniest creatures to unimaginable giants, so suddenly become extinct, leaving only relatively small animals?

It was these groups that at the beginning of the modern Cenozoic era occupied a dominant position in the animal world. And among reptiles, out of 16-17 orders that existed during their heyday, only 4 survived. Of these, one is represented by a single primitive species - hatteria, preserved only on two dozen islands near New Zealand.

The other two orders - turtles and crocodiles - unite a relatively small number of species - about 200 and 23, respectively. And only one order - squamates, which includes lizards and snakes, can be assessed as thriving in the current evolutionary era. This is a large and diverse group, numbering more than 6,000 species.

Reptiles are distributed throughout the globe, except Antarctica, but extremely unevenly. If their fauna is most diverse in the tropics (in some regions there are 150-200 species), then only a few species penetrate into high latitudes (in Western Europe only 12).

Land vertebrates arose in the Devonian. These were armored amphibians, or stegocephali. They were closely associated with bodies of water, since they reproduced only in water and lived near bodies of water, where there was terrestrial vegetation. The development of spaces remote from bodies of water required a significant restructuring of the organization: adaptation to protecting the body from desiccation, breathing atmospheric oxygen, walking on solid substrate, the ability to reproduce outside of water and, of course, improving forms of behavior. These are the main prerequisites for the emergence of a qualitatively different new group of animals. All of the above traits took shape in reptiles.

To this we must add that by the end of the Carboniferous there were strong changes in the natural environment, which led to the emergence of a more diverse climate on the planet, the development of more diverse vegetation, its distribution in areas remote from water bodies, and in this regard to the wide spread of tracheal-breathing arthropods, i.e. .e. possible feeding objects also spread to the watershed areas of the land.

The evolution of reptiles proceeded very quickly and violently. Long before the end Permian period Paleozoic they replaced most of the stegocephalians. Having gained the opportunity to exist on land, reptiles in a new environment encountered new and extremely diverse conditions. The versatility of this diversity and the absence of significant competition on land from other animals were the main reasons for the flourishing of reptiles in subsequent times. Mesozoic reptiles are primarily terrestrial animals. Many of them are secondary in one way or another

adapted to life in water. Some have mastered the air. The adaptive divergence of reptiles was astonishing. The Mesozoic is rightly considered the age of reptiles.

Early reptiles. The oldest reptiles known from the upper Permian deposits of North America, Western Europe, Russia and China. They are called cotylosaurs. In a number of characteristics they are still very close to stegocephalians. Their skull was in the form of a solid bone box with openings only for the eyes, nostrils and parietal organ, the cervical spine was poorly formed, the sacrum had only one vertebra; the cleithrum, a skin bone characteristic of fish, was preserved in the shoulder girdle; the limbs were short and widely spaced.

Cotylosaurs turned out to be very interesting objects, numerous remains of which were found by V.P. Amalitsky in Permian deposits of Eastern Europe, on Northern Dvina. Among them are the three-meter herbivorous pareiasaurs (Pareiasaurus).

It is possible that cotylosaurs were descendants of Carboniferous stegocephalians - embolomeres.

In the Middle Permian, cotylosaurs reached their peak. But only a few survived until the end of the Permian, and in the Triassic this group disappeared, giving way to more highly organized and specialized groups of reptiles that developed from various orders of cotylosaurs (Fig. 114).

The further evolution of reptiles was determined by their variability due to the influence of very diverse living conditions that they encountered during reproduction and settlement. Most groups acquired greater mobility; their skeleton became lighter, but at the same time stronger. Reptiles consumed a more varied diet than amphibians. The technique of its extraction has changed. In this regard, the structure of the limbs, axial skeleton and skull underwent significant changes. For the majority, the limbs became longer, and the pelvis, gaining stability, was attached to two or more sacral vertebrae. The cleithrum bone has disappeared in the shoulder girdle. The solid shell of the skull has undergone partial reduction. In connection with the more differentiated muscles of the jaw apparatus, pits and bone bridges separating them appeared in the temporal region of the skull - arches that served to attach a complex system of muscles.

The main groups of reptiles are discussed below, a review of which should show the exceptional diversity of these animals, their adaptive specialization and probable relationship with living groups.

In the formation of the appearance of ancient reptiles and in assessing their subsequent fate, the characteristics of their skull are essential.

Rice. 114. Cotylosaurs (1, 2, 3) and pseudosuchia (4):
1 - pareiasaurus (Upper Permian), skeleton; 2 - pareiasaurus, restoration of the animal; 3 - Seymouria; 4 – pseudosuchia

The primitiveness of stegocephalians ("whole-skull") and early reptiles was expressed in the structure of the skull by the absence of any cavities in it, except for the ocular and olfactory ones. This feature is reflected in the name Anapsida. The temporal region of reptiles of this group was covered with bones. Turtles (now Testudines, or Chelonia) became probable descendants of this trend; they retain a continuous bony cover behind their eye sockets. Similarities with current forms are found in turtles known from the Lower Triassic of the Mesozoic. Their fossil remains are confined to the territory of Germany. The skull, teeth, and shell structure of ancient turtles are extremely similar to modern ones. The ancestor of turtles is considered to be the Permian Eunotosaurus(Eunotosaurus) is a small lizard-like animal with short and very wide ribs that form something like a dorsal shield (Fig. 115). He did not have an abdominal shield. There were teeth. Mesozoic turtles were originally land-dwelling and apparently burrowing animals. Only later did some groups switch to an aquatic lifestyle and, as a result, many of them partially lost their bony and horny shells.

From the Triassic to the present day, turtles have retained the main features of their organization. They survived all the trials that killed off most reptiles, and are just as thriving today as they were in the Mesozoic.

Today's hidden-necked and side-necked ones retain their primary appearance to a greater extent. land turtles Triassic Marine and soft-skinned animals appeared in the late Mesozoic.

All other reptiles, both ancient and modern, acquired one or two temporal cavities in the structure of the skull. They had one, lower, temporal cavity synapsid. One superior temporal cavity is noted in two groups: paranoid and euryansid. And finally, two depressions had diapsid. The evolutionary fate of these groups is different. The first to move away from the ancestral trunk synapsids(Synapsida) - reptiles with lower temporal cavities, bounded by the zygomatic, squamosal and post-orbital bones. Already in the Late Carboniferous, this group of the first amniotes became the most numerous. In the fossil record they are represented by two successively existing orders: pelycosaurs(Pelicosauria) and therapsids(Therapsida). They are also called bestial(Theromorpha). Animal-like animals experienced their heyday long before the first dinosaurs appeared; cotylosaurs were their direct relatives. In particular, pelycosaurs(Pelicosauria) were still very close to cotylosaurs. Their remains were found in North America and Europe. In appearance they looked like lizards and were small in size - 1-2 m, had biconcave vertebrae and well-preserved abdominal ribs. However, their teeth sat in the alveoli. In some, teeth differentiation was evident, albeit to a small extent.

In the Middle Permian, pelycosaurs were replaced by more highly organized ones. beast-toothed(Theriodontia). Their teeth were clearly differentiated, and a secondary bony palate appeared. The single occipital condyle split into two. The lower jaw was mainly represented by dentary bone. Position

limbs also changed. The elbow moved back and the knee moved forward, and as a result the limbs began to occupy a position under the body, and not on the sides of it, as in other reptiles. The skeleton appeared to have many features in common with mammals.

Numerous Permian beast-toothed reptiles were very diverse in appearance and lifestyle. Many were predators. Perhaps this was the one found by the expedition of V.P. Amalitsky in the sediments of the Permian period on the Northern Dvina inostranzevia(Inostrancevia alexandrovi, Fig. 116). Others ate a plant-based or mixed diet. These unspecialized species are closest to mammals. Among them it is necessary to point out Cynognathus(Cynognathus), which had many progressive organizational features.

Animal-toothed animals were numerous in the Early Triassic, but with the appearance predatory dinosaurs they disappeared. Interesting materials presented in Table 6 indicate a sharp reduction in the diversity of animal-like animals throughout the Triassic. Animal-like animals are of great interest as the group that gave rise to mammals.

Rice. 116. Animal-toothed:
1 - Inostracevia, Upper Permian (restoration of an animal), 2 - skull of Cynognathus

Table 6

The relationship between the genera of beast-like and sauropsid (lizard-like reptiles) at the end of the Paleozoic - beginning of the Mesozoic
(P Robinson, 1977)

The next group to split off from the anapsid cotylosaurs were diapsid(Diapsida). Their skull has two temporal cavities, located above and below the postorbital bone. Diapsids at the end of the Paleozoic (Permian) gave an extremely broad adaptive radiation to systematic groups and species, which are found both among extinct forms and among living reptiles. Among the diapsids, two main groups (infra-classes) have emerged: infra-class Lepidosauromorphs(Lepidosauromorpha) and infraclass Archosauromorphs(Archosauromorpha).

Paleontologists do not have accurate information to say which of them is older and younger in terms of time of appearance, but their evolutionary fate is different.

Who are lepidosauromorphs? This ancient infraclass unites living hatteria, lizards, snakes, chameleons and their extinct ancestors.

Hatteria, or Sphenodon(Sphenodon punctatus), now living on small islands off the coast of New Zealand, is a descendant of the proto-lizards, or wedge-toothed ones, quite common in the mid-Mesozoic (superorder Prosauria, or Lepidontidae). They are characterized by many wedge-shaped teeth sitting on the jaw bones and on the palate, like amphibians, and amphicoelous vertebrae.

Lizards, snakes and chameleons now make up the wide variety of the order Squamata. Lizards are one of the oldest advanced groups of reptiles, their remains are known from. Upper Permian Scientists have discovered many similarities between lizards and Sphenodon. Their limbs are widely spaced and the body moves, curving the spinal column in waves. Interestingly, among their common morphological similarities is the presence of an intertarsal joint. Snakes appear only in chalk. Chameleons are a specialized group of a later era - the Cenozoic (Paleocene, Miocene).

Now about the fate of archosauromorphs. Archosaurs are considered the most amazing of all reptiles that ever lived on Earth. Among them are crocodiles, pterosaurs, and dinosaurs. Crocodiles are the only archosaurs that have survived to this day.

Crocodiles(Crocodylia) appear at the end of the Triassic. Jurassic crocodiles are significantly different from modern ones in the absence of a true bony palate. Their internal nostrils opened between the palatine bones. The vertebrae were still amphicoelous. Modern crocodiles with a fully developed secondary bony palate and procoelous vertebrae descended from ancient archosaurs - pseudosuchians. They are known from the Cretaceous (about 200 million years ago). Most lived in fresh water bodies, but true marine species are also known among the Jurassic forms.

Winged lizards, or pterosaurs(Pterosauria), represent one of the wonderful examples specializations of Mesozoic reptiles. These were flying animals of a very peculiar structure. Their wings were folds of skin stretched between the sides of the body and the very long fourth finger of the forelimbs. The wide sternum had a well-developed keel, like that of birds; the skull bones fused early; many bones were pneumatic. The jaws extended into a beak bore teeth. The length of the tail and the shape of the wings varied. Some ( Rhamphorhynchus) had long narrow wings and a long tail; they apparently flew in a gliding flight, often gliding. Other's ( pterodactyls) the tail was very short and the wings were wide; their flight was more often rowing (Fig. 117). Judging by the fact that the remains of pterosaurs were found in the sediments of salt water bodies, these were inhabitants of the coasts. They ate

fish and behavior, apparently, were close to gulls and terns. The sizes varied from a few centimeters to a meter or more.

The largest among flying vertebrates belong to the Late Cretaceous winged lizards. These are pteranodons. Their estimated wingspan is 7-12 m, body weight is about 65 kg. They are found on all continents except Antarctica.

Paleontologists suggest a gradual decline in the evolution of this group, which coincided with the appearance of birds.

Dinosaurs(Dinosauria) are known in the fossil record from the mid-Triassic. They are the largest and most diverse group of reptiles ever to live on land. Among the dinosaurs there were small animals, with a body length of less than a meter, and giants up to almost 30 m long. Some of them walked only on their hind legs, others - on all four. The general appearance was also very diverse, but in all of them the head was small relative to the body, and the spinal cord in the sacral region formed a local expansion, the volume of which exceeded the volume of the brain (Fig. 118).

At the very beginning of their formation, dinosaurs were divided into two branches, the development of which proceeded in parallel. A characteristic feature of them was the structure of the pelvic girdle, and therefore these groups are called lizard and ornithischian.

Lizard-pelvic(Saurischia) were originally relatively small predatory animals that moved in leaps only on their hind legs, while the front legs served for grasping food. The long tail also served for support. Subsequently, large herbivorous forms appeared that walked on all four legs. These included the largest vertebrates that ever lived on land: brontosaurus had a body length of about 20 m, diplodocus- up to 26 m. Most of the giant lizards were apparently semi-aquatic animals and fed on lush aquatic vegetation.

Ornithischian(Ornithischia) got their name due to their elongated pelvis, similar to the pelvis of birds. Initially, they moved on only elongated hind legs, but later species had both proportionately developed pairs of limbs and walked on four legs. By the nature of their diet, ornithischians were exclusively herbivorous animals. Among them - iguanodon, walking on its hind legs and reaching a height of 9 m. Triceratops in appearance it was very similar to a rhinoceros, usually possessing a small horn at the end of its muzzle and two long horns above the eyes. Its length reached 8 m. Stegosaurus was distinguished by a disproportionately small head and two rows of high bone plates located on the back. Its body length was about 5 m.

Rice. 118. Dinosaurs:
1 - iguanodon; 2 - brontosaurus; 3 - diplodocus; 4 - triceratops; 5 - stegosaurus; 6 – ceratosaurus

Dinosaurs were distributed throughout almost the entire globe and lived in extremely diverse environments. They inhabited deserts, forests, and swamps. Some led a semi-aquatic lifestyle. There is no doubt that in the Mesozoic this group of reptiles was dominant on land. Dinosaurs reached their greatest prosperity during the Cretaceous, and by the end of this period they became extinct.

Finally, it is necessary to recall another group of reptiles in whose skull there was only one superior temporal cavity. This was typical for parapsids and euryapsids. It has been suggested that they evolved from diapsids by losing the lower cavity. In the fossil record they were represented by two groups: ichthyosaurs(Ichthyosauria) and plesiosaurs(Plesiosauria). Throughout the Mesozoic, from the Early Triassic to the Cretaceous, they dominated marine biocenoses. As noted by R. Carroll (1993), reptiles became secondary aquatic whenever life in water turned out to be more advantageous in terms of the availability of food sources and a small number of predators.

Ichthyosaurs(Ichthyosauria) occupied in the Mesozoic the same place that cetaceans now occupy. They swam, bending their body in waves, especially its tail part, their fins served for control. Their convergent resemblance to dolphins is striking: a spindle-shaped body, an elongated snout and a large two-lobed fin (Fig. 119). Their paired limbs turned into flippers, while the hind limbs and pelvis were underdeveloped. The phalanges of the fingers were elongated, and the number of fingers in some reached 8. The skin was bare. Body sizes varied from 1 to 14 m. Ichthyosaurs lived only in water and ate fish, partly invertebrates. It was established that they were viviparous. Ichthyosaurs appeared in the Triassic and went extinct at the end of the Cretaceous.

Plesiosaurs(Plesiosauria) had other than ichthyosaurs, adaptive features in connection with life at sea: a wide and flat body with a relatively underdeveloped tail. Powerful flippers served as swimming tools. Unlike ichthyosaurs,

They had a well-developed neck carrying a small head. Their appearance resembled pinnipeds. Body sizes range from 50 cm to 15 m. The lifestyle was also different. In any case, some species inhabited coastal waters. They ate fish and shellfish. Having appeared at the beginning of the Triassic, plesiosaurs, like ichthyosaurs, became extinct at the end of the Cretaceous period.

From the above brief overview of the phylogeny of reptiles, it is clear that the vast majority of large systematic groups (orders) became extinct before the beginning of the Cenozoic era and modern reptiles represent only pitiful remnants of the richest Mesozoic reptile fauna. The reason for this grandiose phenomenon is understandable only in the most general outline. Most Mesozoic reptiles were extremely specialized animals. The success of their existence depended on the presence of very unique living conditions. One must think that one-sided deep specialization was one of the prerequisites for their disappearance.

It has been established that although the extinction of individual groups of reptiles occurred throughout the Mesozoic, this became apparent at the end of the Cretaceous period. At this time, in a relatively short period of time, most Mesozoic reptiles became extinct. If it is fair to call the Mesozoic the age of reptiles, then it is no less justified to call the end of this era the age of the great extinction. It should be taken into account that significant changes in climate and landscapes occurred during the Cretaceous. This coincided with significant redistributions of land and sea and movements of the earth's crust, which led to enormous mountain-building phenomena, known in geology as the Alpine stage of mountain building. It is believed that at this time a large cosmic body passed near the Earth. Violations of the existing living conditions in this regard were very significant. However, they consist not only in changes in the physical state of the Earth and other conditions of inanimate nature. In the middle of the Cretaceous period, the Mesozoic flora of conifers, cycads and other plants was replaced by representatives of a new type of flora, namely angiosperms. Genetic changes in the nature of the reptiles themselves cannot be ruled out. Naturally, all this could not but affect the success of the existence of all animals and specialized ones in the first place.

Finally, we must take into account that by the end of the Mesozoic, incomparably more highly organized birds and mammals, which played an important role in the struggle for existence between groups of terrestrial animals, were increasingly developing.

Figure 120 gives general scheme phylogeny of reptiles.

Reptiles have their origins in the Paleozoic, when Carboniferous period"They separated from the ancient stegocephalic amphibians. The diverse evolution of reptiles, which resulted in a complex picture of adaptations to various living conditions, lasted a very long time: G. F. Osborne (1930) is inclined to determine the duration of this process at 15-20 million years.

Rice. 1. Skull and lower jaw Therocephalia: Scylacosaurns sclateri ( A) and Cynognathus cratero-notus ( IN) from Perm ( A) and Triassic (IN) South Africa. The first of the early Therocephalia, the second of Cynodontia.

1-praemaxillare; 2-septomaxiliare; 3-maxillare; 4-nasale; 5 - frontal; 6-lacrymale; 7-adlacrymale; 8-postfrontal; 9-postorbitale; 10 -parietale; 11 - jugale; it-squamosum; 13-quadratum; 1 4-day tale; 15 -angu-lare; 16-supraangulare; 17-articulare; 18-Inferior temporal fossa.

By virtue of various conditions, some of which are only difficult to account for due to the plasticity of organization, environmental influences and a number of other reasons, reptiles have undergone a complex evolution in the history of their development. They took possession of a diverse environment: land, water, air, and in the development of some groups there were observed, as we will see later, some returns of adaptations to that living environment, which was once dominant for a given group (for example, sea turtles).

Due to the large number and diversity of individuals, the taxonomy of extinct reptiles presents significant difficulties and lacks unity. Thus, F. Broili, E. Koken and M. Schlosser (1911) count 10 orders of extinct and recent reptiles, M. V. Pavlova (1929) -13, G. F. Osborne (1930) - 18, Abel (1924) -20.

Rice. 2. Thaumatosaurus victor, plesioSaurus, 3.44 m long from the Upper TriassicYuzhnoah Germany.

First of all, it should be noted that the differences between these “orders” are so striking and significant [it is enough to point out, for example, the calico-skulls (Cotylosauria), the helmet-skulls (Pelyco-sauria) or the ichthyosaurs and plesiosaurs] that for the taxonomy of recent animals it becomes the obvious inevitability of a sharper taxonomic differentiation. Many of the mentioned orders, in our opinion, are more correct and natural to consider as subclasses. True, in some systems a unifying grouping into subclasses is adopted based on the structure of the temporal fossa and arches (Anapsida, Diapsida, Syn,apsida and Parapsida). However, many quite compelling objections can be raised against the rationality of such a division.

The temporal region of the skull in the process of evolution of one group, for example, in turtles, has undergone such significant changes that, on the basis of purely external morphological features (without taking into account the picture of the evolutionary process), some of the turtles (modern marine ones with a solid wall of the temporal region) should be attributed to Anapsida, others - to Synapsida. In systematic divisions, we are based primarily on specific, existing morphological characters, and not on speculative data from an evolutionary process that has not yet been fully identified. Therefore, varying even in smallgroup, the structure of the temporal region cannot serve as a criterion for establishing subclasses, as M. V. Pavlova does (1929), but only as a control auxiliary feature for analyzing the development process of diverse branches of reptiles.

Review of some subclasses and phylogenetic relationships with other vertebrates. The most primitive group is the subclass of cauldrons (Cotylosauria), distinguished by a quilted skull, awkward rather high five-fingered limbs, and amphicoelous vertebrae. The first representatives of this subclass, undoubtedly related to stegocephalic amphibians, appear already in the Upper Carboniferous deposits, reach a special peak in the Permian deposits and end their existence in the Triassic.

The best known representatives of this subclass are the Pareiasauras, which were first known in a significant number of forms from slates and sandstones of the Permian Karoo Formation (in southern Africa). In relatively recent times, many skulls and skeletons of pareiasaurs were discovered by Prof. V. P. Amalitsky on the Northern Dvina. These were large, massive forms. For example, the length of the skeleton of R. karpinskii reaches 2 m 45 cm, the length of the skull of this animal is 48 cm. Peculiar appearance had a labidosaurus (Labidosaurus hamatus), a small (up to 70 cm long), short-tailed animal from the Permian deposits of Texas.

Rice. 3. Reconstruction of the skeleton of Eunnotosaurus africanus from the Permian layers (reduced).

Helmet-skull reptiles (Pelyeosauria)

Belonged to Varanops from the Lower Permian of Texas. It was an agile long-tailed animal. Osborne is inclined to consider it the prototype of the wholea number of further reptiles: alligators, lizards, dinosaurs. Some extremely specialized forms belong to the mentioned subclass, for example, Dimetrodon gigas from the Permian deposits of Texas, a predatory reptile in which the upper processes of the dorsal vertebrae were extremely elongated. Between these processes, a fold of skin was probably stretched, giving the animal a completely unusual appearance.

Subclass of reptiles (Theromorpha)

Divided into at least three orders (Fig. 1), it is especially interesting for the structure of heterodoite teeth, differentiated into groups, canines and molars. Further it can be noted; development of the coronoid process on the lower jaw, the presence of a double condyle in the occipital region of the skull for articulation with the vertebrae.

Rice. 4. Thalassemys marina shell (Upper Jurassic).

Some species of beast-like animals reached significant sizes, for exampleMer, Inostrancevia alexandri, up to 3 m long. Many remains of several species of Theromorpha were obtained by the expedition of Prof. V. P. Amalitsky on the Northern Dvina.

Based on the location of the skeletal remains, it can be assumed that they weretrekked along the edges of the ancient riverbeddisappeared river. In addition to the findings of Severodvinsk reptiles, the closest relatives of these reptiles were found in the Permian layersNorth America and in the Karoo strata South Africa. These data show that the ancient Permian animal-like fauna was relatively uniform.

Rice. 5. Shell and skeleton of Archelon chyros (Upper Cretaceous, North America).

An extremely specialized subclass consisted of ichthyosaurs (Ichthyosauri a) - marine animals with a bare fusiform body, a narrow elongated snout, and reduced hind limbs; their forelimbs turned into long flippers. On the back there are sharp fins similar to the fins of sharks; tail with a bilobed shark-type fin. The skull has one pair of temporal arches; on the jaws a large number of sharp cone-shaped teeth.

Ichthyosaurs, as the history of their development shows, descended from terrestrial forms; Subsequently, species that had adapted to pelagic life again returned to the state of coastal existence, and females laid eggs on the sands near the shallows. Then a secondary process of adaptation took place, and these animals, which arose from the Triassic, ended their existence in the Cretaceous era in the form of true inhabitants of the open sea, and they developed an important adaptive feature - viviparity. Thanks to their ability to swim for long periods of time, ichthyosaurs made huge migrations.tions. Osborne (1930) determines the length of such journeys from the shores of Spitsbergen to the Antarctic zone.

Rice. 6. DiploclocTis carnegii - diplodocus from the Upper Jurassic of North America

Plesiosaurs constituted a unique subclass of marine animals.(Piesiosauria; Fig. 2), living from the Triassic to the Upper Cretaceous. They were distinguished by pasty limbs and differently developed dental apparatus, adapted for gnawing hard mollusk shells. The skull is characterized by only one pair of temporal holes, and the spine has weakly amphicoelous, almost platycoelous vertebrae. The length of the neck varied: in many species (Elasmosaurus) the neck reached an enormous length and contained up to 76 vertebrae. The ratio of the length of the neck to the length of the body, which reached 3 m, was 23:9. In other forms, such as the Cretaceous Brachauchenius, the neck was shortened and contained only 13 vertebrae. Body sizes varied greatly. Along with relatively small animals 1.5 m long (Plesiosaurus macrocephalus), there were giants 13 m long (Elasmosaurus).

We now turn to a brief overview of the evolution of turtles (Chelonia). Some authors consider the ancestor of Triassic turtles Placodus gigas, region which has flat teeth, relatively small on the jaws and especially wide and large on the palate. there was no occipital condyle in the placodus skull, and the processes of the occipital bones entered into the corresponding depressions of the first cervical vertebra. All these distinctive features make Placodus stand out completely.

Apparently, the original form for turtles can be considered Eunnotosaurus africanus (Fig. 3) from the Permian layers of the Cape Colony of Africa. This wonderful reptile has 8 middle thoracic ribs that are extremely expanded, adjacent to each other at their edges and forming, as it were, a bony shield. Eunnotos aurus also has teeth on the jaws and palate; this animal led a life similar to that of land turtles.

Already in the Triassic, cryptonecks arose. Their evolution is full of deep interest. Probably, in Jurassic times, a group separated from terrestrial turtles, first adapting to life in the coastal zone, and then gradually moving to the open sea. In this regard, these turtles have a simplified dorsal armor, which, in addition, has become lighter due to the development of marginal notches; the ventral carapace lost its integrity and received a significant fontanelle in the middle part (in Thalassemys marina from Upper Jurassic deposits; Fig. 4). This process of armor reduction was greatly advanced in undoubted open-sea forms, such as the North American Upper Cretaceous Archelonis (Figure 5). Highly intelligentresno, that in early Tertiary times a branch separated from these pelagic formsinhabitants coastal zone. They have a shell again becomes more array nym and is composed of small polygonal plates. These coastal creatures changed the littoral station for the second time to pelagic, which in its the turn caused a secondary reduction of the shell. In modern leatherbacks, a descendant of secondary migrants, the reduced carapace contains derivatives of the primary and secondary leg skeletons. But in any case, the shell of turtles that have again switched to life in the open sea is built on a different principle than that of ancient pelagic species. In 1803, Louis Dollo formulated the law of the irreversibility of the evolutionary process. According to this law, any branch of animals, having taken a certain direction in its specialization, can in no case go back along the same path. In the described case, we have, as it were, a repetition of the evolutionary process. However, it should be especially emphasized that although adaptations in turtles to the pelagic environment secondarily caused a number of corresponding changes in the animal’s body, yet the picture of evolution morphological characteristics was different in this case and did not follow the old path.

Higher the antiquity of lizard-eaters was indicated(Rhynchocephalia). Here in addition To history of this subclass, it can be indicated that the most ancient representatives(Palaeohatteria longicaudata) are known from the Lower Permian layers near Dresden and that this subclass has survived to this day in the person of a single recent representative.

Rice. 7. Brontosaurus excelsus (Lower Cretaceous, North America)

The subclass of crocodiles has its roots in the Triassic. Primary forms crocodiles (for example, Scleromochlus taylori) were small in size,long tail, shortened sharp muzzle. In terms of distribution, the extinct species were confined to freshwater bodies of water, although purely pelagic species were also found (Jurassic Teleosauridae and Geosauridae).

From the Triassic to the Upper Cretaceous, representatives of the subclass of dinosaurs (Dinosauria) lived - a heterogeneous group, divided into several orders. Characterized by the presence of two pairs of temporal arches. They varied in size and appearance; some representatives reached the size of a domestic cat,others are of enormous length, more than 20 m. Giants, like the Brontosaurus excelsus, Fig. 7 or Diplodocus carnegii, Fig. 6, both from the Upper Jurassic, were distinguished by the enormous length of their neck and tail, were herbivorous and moved slowly on four limbs. Other species, such as the Jurassic North American ceratosaurus (Ceratosaurus nasicornis) or the tyrannosaurus (Tugapposaurus rex), were true predators. Guanodonts, huge herbivorous reptiles that walked on their massive hind limbs, also made up a unique group. The skeleton of the huge Trachodon amu rensis was found near Blagoveshchensk (on the Amur) and restored by Prof. N. A. Ryabinin. Concluding our brief overview of this subclass, let us mention the stegosaurs, which were characterized by the presence of large bony plates and spines located along the back and tail.

Rice. 8. Pterodactylus spectabilis (Jurassic)

Dinosaurs, so abundantly represented, became extinct without a trace. The reasons for the death of this group are largely unclear. It is possible that the factors of processes of deep, excessive specialization and increased growth played a role here (C. Depere,1915), which led to the body’s loss of plasticity and adaptability to living conditions that continued to gradually change. It is possible that there was also vital competition with other more adapted organisms.

A completely unique subclass was made up of Jurassic and Cretaceous winged lizards (Pterosauria), which included two orders: rhamphorhynchus and pterodactyls (Fig. 8). These reptiles have reached extreme specialization in their forelimbs with a very elongated fifth finger and the presence of real flight membranes on narrow, long, sharp wings. The tail varied in length; in some forms it was reduced. The skull was elongated, sometimes beak-shaped; teeth of thecodont type or were completely absent. Some forms were distinguished by a huge wingspan (in Pteranodon, up to 7 m). The paleontological history of the modern most species-rich subclass of squamates (Squamata) is relatively poorly studied. A reliable ancestor This group can be considered Permian Araeoscelis gracilis. (For the relationship diagram, see Fig. 9).

Rice. 9. Scheme of the evolutionary development of reptiles and related relationships of various groups.

The main subclasses of extinct and modern reptiles

Subclass 1. Cauldron-skulls - Cotylosauria (Permian-Triassic).

2. Helmetocranial-Pelycosauria (Permian-Triassic).

"3. Animal-like Theromorpha (Permian-Triassic).

» 4. Ichthyosaurs - Ichthyosauria (Triassic-Cretaceous).

"5. Plesiosaurs-Plesiosauria (Triassic-Upper Cretaceous).

"6. Lamellar tooth Placodontia (Triassic).

"7. Lizard-eaters-Rhynchocephalia (from the Lower Permian to the modern).

"8. Turtles-Chelonia (from Permian and Triassic to modern)

"9. Crocodiles-Crocodilia (from Triassic to modern).

"10. Dinosaurs-Dinosauria (from Triassic to Upper Cretaceous).

"eleven. Winged lizards-Pterosauria (Jurassic).

"12. Squamate-Squamata (from Permian to modern).

Article on the topic Evolution of reptiles