Terrestrial dinosaurs. Kinds of dinosaurs, all kinds of dinosaurs. Dinosaur Classification Problems Today

03.05.2020

Dinosaurs, which in Greek means terrible (terrible) lizards (lizards), are a superorder of aboveground vertebrates that existed and led an active lifestyle throughout the Mesozoic era. Dinosaurs are considered the first vertebrates that settled throughout the planet, while their ancestors - amphibians were forced to live only near water bodies, to which they were tied due to the specifics of reproduction. The finds of the first representatives of dinosaurs date back to 225 million years BC. e. During the history of its existence, which lasted for 160 million years, this superorder multiplied extremely, giving a huge number of varieties. Scientists assume that the number of genera of dinosaurs at the time of the peak of their prosperity could reach 3400, although so far, as of 2006, only 500 of them have been confidently described. Each genus had an indefinite number of species. As of 2008, 1047 varieties of these ancient vertebrates have been described. And at the moment, as a result of new archaeological discoveries, this number is increasing.

On the border of the Mesozoic and Cenozoic, a certain global upheaval occurred, which served mass extinction of dinosaurs, after which only miserable units remained from the reptiles that dominated throughout the Mesozoic.

Classification of dinosaurs according to the method of pelvic bones

Dinosaurs can be classified in different ways. It is convenient for some, due to the specifics of their works and literary works, to sort the ancient vertebrates of the Cretaceous period by size, for others by belonging to the habitat, since at that time there were aquatic reptiles, both land and aeronautical. Someone prefers to divide dinosaurs into bipeds and quadrupeds. But the main accepted form of classification is classification of dinosaurs according to the method of pelvic bones, proposed back in 1887 by the famous English paleontologist G. Seeley.

Rice. 1 - Classification of dinosaurs

Despite the fact that the ancestors of all dinosaurs without exception is considered a group of ancient reptiles archosaurs, at the beginning of the Triassic, their development went in different ways. Since that time it has happened division of reptiles according to the principle of the structure of the pelvis on the:

lizards;
ornithischian.

But this does not at all mean that all lizards originated from lizards, and birds from ornithischians. These are conditional names associated only with the fact that in lizards the pubic bones of the pelvis were initially directed forward, in the manner of modern crocodiles, while in ornithischians they were directed backwards, in the manner of a bird.

In appearance, it would be difficult to determine to which group this or that dinosaur belongs. These groups differ much more clearly in the structure of the jaws. Lizards possessed jaws, the rows of teeth in which were located strictly along the edges in one row, reaching the tip of the muzzle. All teeth had a conical or chisel-like shape and each was located in its own separate cell. Ornithischians had lower jaws ending in the anterior part with a predentary bone. Often had no teeth in the front and the upper jaw. Often, the front part of ornithischian dinosaurs simply looked like a massive horny turtle beak.

Lizard dinosaurs

Lizard dinosaurs(Fig. 2) were subdivided into:

theropods- appeared on the borders of the Cretaceous and Jurassic and are the largest representatives of predatory carnivorous reptiles that existed until the end of the Cretaceous period and the global cataclysm that caused the mass extinction of species.
Sauropodomorphs- also originated in the late Triassic, some of which were the most gigantic creatures in the entire history of the Earth. All of them were herbivorous and, in turn, were subdivided into two more subgroups, namely, the prosauropods that lived in the Late Triassic - the Early Jurassic and the later and developed sauropods that replaced them closer to the middle of the Jura.

Rice. 2 - Lizard dinosaur

Theropods were mostly bipedal predators, but there were also omnivores among them, for example, such as therizinosaurus or ornithomimids. Some of the theropods, such as the Spinosaurus, reached 15 meters in height. These predatory representatives of the lizards had three advantages over other dinosaurs, which consisted in:

extreme agility and speed of movement;
unusually developed vision;
freedom of the front paws, since they ran on two unusually developed hind legs, and thus could freely perform any other functions with the front ones.

Gigantic growth often had detrimental consequences for theropods. For example, a Tyrannosaurus rex, catching up with its prey, had to be very careful while running, because with its impressive dimensions (one hind limb reached a height of 4 meters), any wrong step, any bump or uneven ground could cause a fall, which often led to tangible, and sometimes fatal injuries. In its turn, theropods are classified on the:

coelurosaurs, small and nimble bird-like pangolins such as ornithomims and velociraptors;
carnosaurs, predators of large sizes, examples of which were the already mentioned tyrannosaurus and allosaurus.

Sauropodomorphs were the owners of the sacral brain, which exceeded the head in size by 20 times. Despite their huge weight and size, they became frequent victims of predatory dinosaurs. The huge size of these ancient reptiles was the result of the buildup of intestinal mass necessary for the digestion of hard-leaved plants. As a result, along with the stomach, the rest of the body was forced to increase in size. Examples of such lizards were camarosaurs, giraffatitans, brachiosaurs, etc.

Let's take a closer look at theropods using the example of one of the most numerous predators of that Middle Jurassic - allosaurus(Fig. 3). On average, these predators reached 3.5 meters in height at the withers and 8.5 meters in length from muzzle to tail. Their habitat was the North American, South European and East African parts of the ancient mainland Pangea.

Rice. 3 - Allosaurus

Allosaurus had a fairly large skull, their jaws were equipped with a huge number of sharp teeth. In order to balance the body when moving, in contrast to the massive head, there was an equally massive tail, with which the animal often knocked its victims down. A massive head often served the same purpose. Compared to other large terrapods, allosaurs were relatively small, but this gave them more maneuverability and mobility. There is also evidence that large dinosaurs such as some representatives of sauropods, like brontosaurs and thyrophores, like stegosaurus, they hunted in a herd way, like today's wolves. Although many scientists are skeptical that these animals could coexist in packs. In their opinion, for this they had too primitive mental development and extremely strong ferocity and aggressiveness.

Ornithischian dinosaurs

Despite their name, scientists proved that it was not they, but the lizard-hipped dinosaurs that later became avian ancestors. But, returning to ornithischian dinosaurs(Fig. 4), note that they classified into two main suborders, namely:

thyreophores;
cerapods.

Rice. 4 - Ornithischian dinosaur

To thyreophores include such herbivorous dinosaurs as ankylosaurs and stegosaurus. A distinctive feature of these lizards was that their body was partially covered with shell armor, and there were huge shield-like growths on their backs.

In discharge cerapods includes marginocephalians, such as ceratopsians and pachycelosaurs, and all ornithopods, the most massive representative of which was iguanodon(Fig. 5).

Iguanodons had their peak of distribution in the first half of the Cretaceous, and inhabited vast expanses of the European, North American, Asian and African parts of Pangea. 12-meter and 5-ton iguanodons moved on two massive hind legs, in front of the muzzle they had a massive beak, with which they plucked the plants they needed. Next came rows of teeth, more similar to those of iguanas, only much larger.

Rice. 5 - Iguanodon

The forelimbs of Iguanodons were a quarter of the size shorter than the hind limbs. The thumbs were equipped with spikes, with which the animal defended itself from predators. The most mobile of the fingers of the forelimbs were the little fingers. It should be noted that iguanodons could not run, their hind limbs were adapted only for unhurried walking, which is why they often became victims of such predators as allosaurs, tyrannosaurs, etc. The hind limbs had three fingers, like current chickens, and their spine and massive tail were supported by strong tendons.

Dinosaur Classification Problems Today

Many scientists insist that a large number of dinosaurs already described did not previously exist, since some of the described varieties were nothing more than twins of previously described species. The difference between them consisted, allegedly, only in the fact that they were either at an earlier or at a later stage of development. Also, a fairly large group of scientists insists that about 50% of all dinosaurs found were classified and named incorrectly.

Thus, the current paleontologists are divided into two camps. While some continue to further divide the bulk of the found remains of ancient reptiles into all new species based on the identified significant and not very distinctive features, others completely doubt the correctness of the species described earlier.

These giants dominated our planet for more than 160 million years, but at the end of the Cretaceous they completely disappeared as a species. Until now, scientists are finding the remains of dinosaurs, which completely disappeared as a species about 66 million years ago. And even now, their size is amazing!

In total, paleontologists count more than 1000 species of dinosaurs, but only ten of them can be distinguished by a special feature. They do not have outstanding size, are not bloodthirsty, but just very strange.

10 Amargasaurus

This species was first described in 1991, after José Bonaparte discovered the remains in the La Amarga quarry. A distinctive feature of this dinosaur is two rows of spikes on the neck and back, approximately 65 centimeters long. There are no other outstanding qualities in Amargasaurus.

Scientists are still arguing why there were spikes on the back of this lizard. This design significantly reduced the dinosaur's mobility, so protection from predators was in doubt. We can definitely say that the male amagazaurus had longer spikes, which means it used them for mating games.

9 Concavator

This carnivorous dinosaur was first discovered in 2003, and scientists are still arguing over its strange skeleton. The concavator had a small body about 6 meters long and a strange feature - a hump between the 11th and 12th vertebrae of the skeleton.

The hump did not carry any useful function, just like the bumps in the bones of the forearms of the concavenator. But paleontologists were able to take a fresh look at the theory of the relationship between birds and dinosaurs, because before that, no rudiments of feathers were observed in any relative of this dinosaur.

8 Cosmoceratops

Another strange representative of this species belongs to the horned dinosaurs. Perhaps this is where all its advantages ended. The name Kosmoceratops does not come from the word kosmos, but means richly decorated in ancient Greek.

And it really is very richly decorated! Cosmoceratops had 15 horns, and by their number it is the most equipped dinosaur. True, there was no point in them, except that beautiful horns came in handy during mating games.

7 Kulindadromeus zabaikalsky

This miracle animal, as the name implies, was discovered in Russia, in the Kulinda valley in 2010. Since then, the minds of scientists have not stopped digesting information, because culindadronius has violated every conceivable theory about dinosaurs.

It belongs to the group of ornithischian dinosaurs, but does not have wings (or their rudiments). All previously found representatives of this group did not even have the beginnings of feathers, which caused discussion in the scientific worlds. So far, it has been possible to establish that feathers were used by this dinosaur to keep warm and for mating games.

6 Notronich

This wonderful dinosaur belongs to the genus of therapods (predators), but is a herbivore. His remains were discovered in 1998 on a ranch in New Mexico. It had a rather impressive weight - 5.1 tons and a height of about 5 meters.

Now imagine a giant sloth standing on the ground. This is exactly what this dinosaur looked like, which greatly surprised paleontologists. Its huge claws were a completely unnecessary accessory given its herbivory. Nootronichus was very, very slow because of the claws…

5 Oryctodromeus

This ornithischian dinosaur had a very unusual property for its species. Small, only 2.1 meters long and 22 kg in weight, he looked like a modern mole or rabbit.

Yes, the oryctodromeus dug minks and hid in them from predators. It looks like a pretty cute wombat, only many times larger. The sight, obviously, was funny - a dinosaur that lives in a hole and digs the ground with its claws!

4 Ganzhousaurus

This species was discovered in the province of the same name in China in 2013. Scientifically, it is called Qianzhousaurus, and in everyday life - "pinocchio dinosaur". In fact, he is a tyrannosaurus rex, only slightly modified.

The fact is that the ganzhousaurus has a very long jaw, the structure of which defies explanation. Their cousins, tyrannosaurs, have a very massive skull that can withstand powerful blows. Why would a Pinocchio dinosaur with the same body structure have a long jaw that cannot withstand the load is a real mystery.

3 Rhinorex

This species belongs to the genus of herbivorous hadrosaurids, but differs from them in one feature in the structure of the skull. Rhinorex has just a huge nasal plate, which defies any explanation.

The purpose of such a nose in this dinosaur has been discussed by scientists for many years. Like his relatives, he did not have a special sense of smell, so such a growth on his nose is meaningless from the point of view of convenience. The duck-billed dinosaur is still studied and researched by paleontologists.

2 Stygomoloch

Oh, his name is already intimidating - in translation it is "horned demon from the infernal river." This herbivorous dinosaur had a domed skull with horns on the back.

The name Stygimoloch comes from mythology - Moloch (Semitic deity) and Styx (nymph in Hades). Scientists are still arguing why he needed such a strange skull and came to the conclusion that these are again mating games. Stygomoloch fought with rivals with the help of a convex forehead and horns.

1 Yutyrannus

This type of dinosaur was related to the tyrannosaurus rex, although the difference is immediately visible. It was covered with short, chicken-like feathers, about 15 centimeters long. He was a predator, although at first glance, he did not look at all intimidating in these feathers.

At the same time, he had a considerable weight of about two tons. The findings of such dinosaurs are increasingly leading scientists to the idea that all representatives of this species first had feathers, and then lost them during evolution.

Mankind is lucky that these powerful creatures died out many millions of years ago. Even the strangest and most ridiculous of them could destroy a person with one blow.

The beginning of history was the climatic changes that occurred on Earth 300 million years ago. There was a significant increase in average temperature, which contributed to the extinction of some species and the spread of others. In particular, the flowering of reptiles began.

Both the number of individuals and the number of species increased. The ancestors of dinosaurs, the archosaurs, also descended from them. Modern representatives of this group of reptiles are crocodiles. The archosaurs of the Permian period were distinguished by the specific structure of the teeth, as well as by the specific protective covering of the skin - scales. Like modern crocodiles, they are eggs.

Carnivorous dinosaurs fed mainly on small mammals. There were also herbivorous dinosaurs with a plant-based diet.

After the Mass Permian, only 5% of pre-existing species, and the ancestors of dinosaurs managed to survive this ecological upheaval. The dinosaurs themselves originated 230 million years ago. The earliest dinosaur species known to scientists is the Staurikosaurus. It was about 2 m long and weighed up to 30 kg. Staurikosaurus was a predator and moved on its hind legs.

The age of the dinosaurs and their decline

Gradually, dinosaurs became an increasingly diverse group of creatures, capturing more and more new habitats. Dinosaurs could also live in water, competing with large predatory fish. Gradually, flying dinosaurs appeared. Also, over time, the sizes of reptiles became more and more diverse - their weight could reach 200 kg or more.

Dinosaurs flourished during the Cretaceous and Jurassic periods, when dinosaur species accounted for more than half of all species of the Earth's fauna. In total, the remains of about 500 species of dinosaurs were found, but scientists believe that there were much more of them - up to 2000 during the entire existence of this superorder.

The largest dinosaurs were herbivores or lived in water.

The exact reason for the extinction of the dinosaurs remains unknown. One theory suggests that dinosaurs died due to a meteorite fall and the resulting tsunami and other cataclysms. Other scientists believe that the reason was the gradual climate change, which led to the extinction of not only dinosaurs, but also a number of other species - up to 20% of flora and fauna species disappeared. What is known for sure is that the dinosaurs disappeared at the end of the Cretaceous period - about 65 million years ago. The dominance of reptiles was replaced by a wide distribution of mammals.

Dinosaur species of this group lived in the late Jurassic period on the territory of modern North America about 150 million years ago. Paleontologists consider diplodocus to be one of the most easily identifiable dinosaurs. Moreover, this species is the largest of all dinosaurs known from complete skeletons found. Diplodocus were herbivores, and their huge size was a deterrent to the predatory lizards of those times - ceratosaurs and allosaurs.

Allosaurus - a thunderstorm of diplodocus!

Within the framework of this article, we will not be able to consider all types of dinosaurs with names, so we will only turn to the most prominent and famous representatives of these legendary giants. One of them is the Allosaurus. This is a representative of the genus of carnivorous dinosaurs from the group of theropods. Like diplodocus, allosaurs existed in the Jurassic period about 155 million years ago.

These creatures walked on their hind legs and had very small forelimbs. On average, these lizards reached a length of 9 meters and a height of 4 meters. Allosaurs were considered large bipedal predators of the time. The remains of these insidious creatures were found on the territory of modern Southern Europe, East Africa and North America.

Ichthyosaurs - legendary fish lizards

They represent an extinct detachment of large marine reptiles, reaching a length of 20 meters. Outwardly, these lizards resembled modern fish and dolphins. Their distinguishing feature was large eyes, protected by a bone ring. In general, at a short distance, ichthyosaurs could well be mistaken for fish or dolphins.

The origin of these creatures is still in question. Some paleontologists believe that they come from diapsids. This version is supported only by conjecture: apparently, the shoot of ichthyosaurs somehow branched off from the main diapsid stem even before this subclass split into archosaurs and lepidosaurs. However, the ancestors of these fish lizards are still not known. Ichthyosaurs died out about 90 million years ago.

Dinosaurs take to the sky

At the end of the Triassic period, the first flying species of dinosaurs appeared on the planet, which appeared unexpectedly in the fossil record. Curiously, they were already fully formed. Their direct ancestors, from which they developed all this time, are unknown.

All Triassic pterosaurs belong to the Rhamphorhynchus group: these creatures had huge heads, toothed mouths, long and narrow wings, and a long and thin tail. The size of these "leather birds" varied. Pterosaurs, as they were called, were mostly the size of both gulls and hawks. Of course, among them were 5-meter giants. Pterosaurs died out about 65 million years ago.

Tyrannosaurs are the most famous dinosaur species.

The list of ancient lizards would be incomplete if we did not mention the most majestic dinosaur of all times and eras - the tyrannosaurus rex. This insidious and dangerous creature fully justifies its name. This creature represents a genus from the coelurosaur group and theropod suborder. It includes a single species - a tyrannosaurus rex (from the Latin language "rex" is a king). Tyrannosaurs, like allosaurs, were bipedal predators with massive skulls and sharp teeth. The limbs of Tyrannosaurus Rex were a complete physiological contradiction: massive hind legs and tiny hook-shaped forepaws.

Tyrannosaurus rex is the largest species within its own family, as well as one of the largest terrestrial predatory lizards in the entire history of our planet. The remains of this animal were found in the west of modern North America. According to scientists, they lived about 65 million years ago, that is, it was in their century that the death of the entire dynasty of ancient lizards occurred. It was the tyrannosaurs that crowned the entire great era of dinosaurs, which ended during the Cretaceous period.

Feathered heritage

It is no secret to many people that birds are direct descendants of dinosaurs. Paleontologists saw much in common in the external and internal structure of birds and dinosaurs. It should be remembered that birds are descendants of land lizards - dinosaurs, and not flying lizards - pterosaurs! Currently, two subclasses of ancient reptiles are "hanging in the air" because their ancestors and exact origins have not been established by paleontologists. The first subclass is the ichthyosaurs and the second is the turtles. If we have already dealt with ichthyosaurs above, then nothing is clear at all with turtles!

Are turtles amphibians?

And therefore it is clear that, considering such a topic as "Types of dinosaurs", one cannot fail to mention these animals. The origin of the turtle subclass is still shrouded in mystery. True, some zoologists still believe that they originated from anapsids. However, they are opposed by other pundits who are sure that turtles are the descendants of some ancient amphibians. And they do not depend on other reptiles at all. If this theory is confirmed, then a big breakthrough will occur in the science of zoology: it may happen that turtles will not have the slightest relation to reptiles at all, because then they will become ... amphibians!

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