Ancient reptiles: origin and extinction. Biology at the Lyceum Reproduction and regeneration

Two hundred million years ago, the rulers of our planet were the ancients - the crown of creation of that time! No other class of animal has held “power” for as long as the reptiles.

There were many of them - ancient lizards, crocodiles, tuataria, but the pinnacle of their development was, naturally, dinosaurs. Beastly lizards lived everywhere: on land, in water, in the air!

Dinosaur Science

Ancient reptiles left behind many mysteries that not everyone can solve. Using the remains of the bones of lizard animals, with the right approach, you can “draw” a picture of the past: the external characteristics of the lizard, its way of life, and so on. This is what paleontologists do. Their work is somewhat reminiscent of the work of detectives: broken pieces they have to restore a whole period of life giant reptile! Here you need to be able to competently combine your intuition with logic and imagination, collecting the smallest fragments " past life"of this or that dinosaur.

Restoring pictures of the past is not an easy task. You can’t do without fantasy and a well-developed consistent imagination. Paleontology is, to some extent, a creative science: even a seemingly insignificant fact, if properly substantiated, can play an important role in the chain of events of that era... The Age of Dinosaurs!

A little classification

Reptiles are a rather peculiar group of living beings. The fact is that this class is divided into subclasses, the most primitive and ancient of which are the so-called anapsids. The last of them died out two hundred million years ago. A separate branch of this group is synapsids. These are already the ancestors. The synapsids themselves did not live to see the heyday of their descendants. Even later, a branch of diapsids appeared, which in turn divided into lepidosaurs and archosaurs. The first include both lizards, snakes, and tuataria living in our time, as well as some extinct ones. sea ​​predators with long and snake-like necks called plesiosaurs. Archosaurs include crocodiles, pterosaurs and dinosaurs. These ancient reptiles are almost all extinct. Only crocodiles remained. Are they really the ones? only descendants ancient reptiles? Not certainly in that way!

Feathered Legacy

The direct descendants of dinosaurs are birds. Although this is not the class Reptiles, it is precisely feathered due to its structure and appearance resemble ancient lizards. At the same time, feel the difference: birds are descendants of animal lizards such as the pterosaur Quetzalcoatlus, namely “terrestrial” dinosaurs! died out without leaving a legacy.

Death of a dynasty

Ancient reptiles were very diverse and numerous, in their perfection and organization no other could compare with them. Animal lizards were studied and continue to be studied with greater interest than others. The collapse of the “dinosaur empire” still gives rise to a lot of theories, disputes, and versions. For whatever reason, the death of the dynasty of reptiles ruling the world occurred, several million years passed before the Earth was able to recover from the global catastrophe. When this did happen, then giant dinosaurs there was no longer room for it. They are extinct forever. Instead, others appeared - beautiful and strong animals! But you and I already know that one small group of descendants of ancient reptiles still managed to survive, and today its representatives are all around us... These are birds!

The world of modern reptiles numbers about 6,300 species, which represent the remains of a numerous and diverse Mesozoic era class that dominated on land and in water. Currently existing representatives of reptiles are united into four orders: Primal Beasts, Scaly, Turtles, Crocodiles.

First Beast Squad

Currently represented by the only species - hatteria. Lives on the islands of New Zealand. Retains primitive structural features: movable upper palate, biconcave vertebrae, abdominal ribs, parietal eye.

Order Scaly

There are about 6,100 species of lizards, chameleons, and snakes. The body of all is covered with horny scales. Lizards have an elongated body with a long tail and well-developed limbs. The exception is the spindle, yellow-bellied - legless lizards. The eyes are protected by movable eyelids and a nictitating membrane. The teeth are small and conical. The middle ear is covered by the eardrum. Well developed rib cage. When shedding, the skin comes off in patches.

Snakes have a long, cylindrical, legless body. The eyes are covered by a transparent ocular plate formed as a result of the fusion of the eyelids. The eardrum covering the outside of the middle ear is missing. The sharp teeth are curved back and serve to capture and hold food. U poisonous species the teeth have grooves or channels through which the secretion of the poisonous glands flows. The mouth is capable of greatly stretching due to the suspension of the lower jaw to the skull by tensile ligaments. In addition, the right and left arches of the lower jaw do not grow together, but are connected by an elastic ligament. There is no closed chest. This allows them to swallow large prey. The tongue is forked at the end. Snakes provide benefits by killing rodents. Their poison is used in medicine.

Turtle Squad

There are about 200 species. They have a shell that covers the body from above, from the sides and from below. It consists of a dorsal and ventral shield connected by a bony plate or tendon ligament. The armor develops from overgrown bones of the skeleton, which are covered on top with horny scutes. U land turtles The armor is domed, while in aquatic animals it is flattened. Only the cervical and caudal sections of the spine are mobile, and the rest are fused with the dorsal shield. The jaws are toothless and covered with horns that form sharp cutting blades. The limbs are well developed. Turtles that live in rivers and lakes have a swimming membrane between their toes. In sea turtles, the limbs are modified into flippers.

Squad Crocodiles

There are about 20 species. The body is lizard-like, large - from 1.5 to 6 m, covered with large horny scutes, under which lie bone plates. The nostrils and eyes are raised above the surface of the muzzle. The teeth sit in the cells of the jaws - the alveoli. The heart has four chambers, but the blood is partially mixed. They reproduce by eggs. Females guard the clutches. They feed on fish and mammals.

Origin of reptiles

The separation of the ancestors of reptiles from amphibians began in the Middle Carboniferous. About 320 million years ago, forms separated from primitive stegocephalians, giving rise to cotylosaurs, adapted to life on land.

The formation of terrestrial vertebrates was facilitated by the fact that intensive mountain-building processes took place at the end of the Carboniferous period and the beginning of the Permian. This led to a reduction in the areas of wet biotopes and an increase in the proportion of dry biotopes. Adaptive radiation led to the formation of various types of reptiles that adapted to life on land, water, and air (pterosaurs). These animals reached their greatest prosperity in the Mesozoic era. At the end of the Mesozoic there was a cooling of the climate. Due to the fact that reptiles are not able to maintain a constant body temperature, there was a decrease in vital processes, which resulted in their gradual extinction over the course of 70-90 million years.

Ancient reptiles

Ancient reptiles include dinosaurs and wild-toothed lizards. Dinosaurs appeared at the end of the Triassic period of the Mesozoic era. They ranged in size from rabbits to giants, weighing 30-50 tons, small heads, a long tail. Predators had strong teeth and moved on their hind limbs armed with claws. Herbivorous dinosaurs (diplodocus) had a long tail and a long mobile neck, moved on two pairs of limbs, reached a length of up to 30 m and had a mass of 20-25 tons.

Animal-toothed lizards descended from primitive cotylosaurs of the Carboniferous period. Outwardly they looked like lizards. Their ancient forms had undifferentiated teeth. In later forms, the teeth were differentiated into incisors, canines, and molars. A secondary palate has developed.

Reptiles or reptiles are the oldest class of true vertebrates that settled on land.

Reptiles include different kinds snakes, crocodiles, turtles and lizards.

They were the largest representatives of the dinosaurs that dominated the Earth 150 million years ago.

The animals are direct ancestors despite the fact that they now live in swamps - some of them could fly, and their elongated scales eventually turned into feathers.

Description

The name of the class comes from the word to creep - to move by crawling, dragging your stomach along the ground. This is true - reptiles have no limbs at all; in others they are located almost at the level of the spine.

Unlike amphibians, which are wet and slippery to the touch, reptiles have always dry skin. This helps retain moisture inside the body, which is especially important for inhabitants of arid areas.

Reptiles description

Reptiles are endowed with perfectly protected skin from external influences, including the scorching sun; the skin is covered with scales. Snakes and lizards periodically molt, that is, shed the skin from which they grew, and then grow new skin.

Almost all animals of the class reptiles are colored in accordance with color scheme environment so as not to become easy prey for predators, and so as not to be too noticeable to their victims.

The chameleon became famous for the fact that it can change color depending on many factors - temperature, humidity, thirst, emotional state.

Nutrition

Animals are not able to chew food, they can only tear it into pieces. And snakes generally swallow prey whole, and often the size of the victim exceeds the size of the snake itself.

Reptiles of our Planet

A snake can perform such a trick thanks to its ability to open its mouth very wide; its stomach can stretch to incredible sizes.

Most reptiles live in warm regions - deserts, semi-deserts and tropical rainforests.

They can also be found in cooler natural areas, in deciduous and mixed forests, but much less often.

Unusual reptiles

This is explained by the fact that the body temperature of reptiles is practically no different from the ambient temperature. Therefore, reptiles living in cold areas have to warm up in the sun for a long time. In the warm season they lead active life, and in cold weather they hibernate.

Reptiles lay eggs in a hard protective shell and leave them in nests or simply bury them in the sand.

All of them, with the exception of , do not care about the future fate of their cubs - having hatched from eggs, they already lead independent life. Some species of lizards and snakes are viviparous.

Almost all species of reptiles are listed in the Red Book, some of them are on the verge of extinction.

Reptiles animals snakes photo

On the part of the governments of some countries, measures are being taken, special farms are being created for the reproduction of one or another species that is about to disappear. But this will not help much, since many species of reptiles have already been so exterminated by humans that it is not possible to restore them.

Due to the fact that all processes in the body of reptiles occur very slowly, their life expectancy is very high. Crocodiles live about 70 years, and turtles live more than 150.

1. Reptiles are an important link in the food chain - they feed on insects and small rodents and, thereby, regulate their numbers. The reptiles themselves serve as food for some.
2. Snake venom is the basis of many medicines.
3. Expensive shoes and accessories are made from crocodile and snake skin, and jewelry is made from shells.
4. For this purpose, reptiles are raised on special farms so as not to reduce their numbers in the wild.
5. The meat and eggs of crocodiles and turtles are eaten by residents of many tropical countries.

Reptiles or reptiles– lat. Reptilia, the first class of terrestrial vertebrates that have inhabited our planet for for long years. Primary or ancient reptiles arose from ancient amphibians, and climate change contributed to this. In the ancient era, the climate on the planet gradually became drier and colder, as a result, water bodies began to dry up, large wetlands turned into huge dried out “craters”, etc. Change climatic conditions began to occur due to colossal mountain-building processes.

At this time, most of the ancient amphibians became extinct, due to the presence of thin and bare skin, poorly developed internal organs and so on. In the rest of the animals, the skin gradually began to horny and harden, the structure of the lungs became more improved, as a result, the ability to better absorb oxygen appeared, the brain of the animals changed, and also the appearance of new way reproduction - laying hard-shelled eggs. This is how the primary or ancient reptiles arose.

The primary reptiles that appeared in the ancient era began to develop quite quickly, as a result of which the ancient amphibians were relegated to the background. In the Middle or Mesozoic era, this development reached its maximum peak, and it was then that vertebrate animals of enormous size began to appear, called ancient reptiles. They filled the entire territory of the planet and gained a dominant position on land, in water and in the air.

The most common species among ancient reptiles or reptiles are:

Squad of crocodiles- predatory vertebrates, only 22 species of crocodiles are now registered.

The meaning of reptiles in nature

Reptiles are a link in food chains of different biogeocenoses. They act as food for many vertebrates ( predator birds), at the same time they themselves feed on invertebrates (mollusks, worms) and small vertebrates (insects, rodents). Reptiles are food for game animals (ferrets, foxes). Crocodiles and snakes play the role of peculiar orderlies of terrestrial and aquatic biogeocenoses, destroying sick and weakened animals.

The importance of reptiles in human life

Humans eat eggs and meat of certain species of lizards (monitor lizards, iguanas), turtles, snakes, and crocodiles.

Turtles are a commercial object.

Example 1

The green sea turtle (soup turtle) reaches a length of 2 m and a weight of 450 kg. Its eggs, meat, and fat are eaten. Turtle soup, which is prepared from this species of turtle, is known throughout the world. In Kazakhstan and Central Asia, the steppe turtle is eaten.

In Asia, in the territory Latin America and African snakes are a gastronomic delicacy. Some restaurants in Asia offer up to 75 dishes made from snake meat. Snake meat is boiled, fried, stuffed, stewed, marinated with various spices and herbs, etc. Residents South China They cannot imagine their diet without snake meat. Usually snakes are eaten during the cold season, that is, from October to March. The Chinese associate the snake with positive masculine, they believe that snake meat “warms” the blood.

Representatives of Scalys destroy pests Agriculture. Thus, snakes eat rodents, and lizards eat a variety of insects.

A variety of decorative items are made from the skin of crocodiles and turtle shells. Boxes, combs, spectacle frames, and various jewelry are made from turtle shells. Leather of crocodiles and some large snakes– a valuable leather material from which belts, bags, suitcases, and shoes are made. In Cuba and the USA there are special farms for breeding crocodiles.

In a number of countries (Africa, South Asia, America) there is no poisonous snakes that feed on small rodents are kept in residential premises instead of cats.

Reptiles: chameleons, turtles, chameleons, snakes often become inhabitants of home terrariums.

Snake venom plays a significant role in medicine in the manufacture of a number of medicines. Vipratox, Lachesis are used for spasm of heart vessels, rheumatism, bronchial asthma. Medications, made from snake venom, are used in the treatment of hemophilia and epilepsy. In many countries, special nurseries for breeding venomous snakes are being created. In captivity, snakes, as a rule, do not reproduce and do not live long, so they are systematically caught in the wild. Scientists have managed to lengthen the lifespan of snakes in captivity: cobras - up to 6 years, vipers - up to 3).

The negative role of reptiles in human life

Some representatives of reptiles are dangerous to humans. Thus, snake bites can be fatal. In our country, the most dangerous bites for humans are viper, cobra, and efa. The viper's bite is not fatal, although it is quite painful.

Note 1

Previously, about 20-30% of victims died from snake bites. Currently, their number has decreased significantly (1-2%), thanks to the use of medicinal serums.

Serums can be monovalent - against poison certain type snakes and polyvalent, which neutralize the venom of several species of snakes.

In certain areas of Central Asia land turtles are capable of causing significant damage to plantings of pistachios, melons and other crops, damaging earthen structures and digging holes. Water snakes can harm fisheries by eating young fish.

Some species of snakes and lizards, land turtles, feeding ticks and larvae, are involved in the transmission of pathogens of a number of diseases to humans and animals.