Stegosaurus- dinosaur jurassic . Stegosaurus- a representative of ornithischian dinosaurs - thyreophore. Stegosaurus- the largest representative of the group of stegosaurus. This group of dinosaurs was named after him.

The head ended in a horny beak, which stegosaurus plucked leaves from undersized vegetation and lower branches of trees.

Stegosaurus Nutrition:

To survive stegosaurus should have eaten a large number of food daily. Since his jaws were poorly developed, and his teeth are not very well adapted for chewing food to facilitate digestion, stegosaurus swallowed stones that helped him grind the leaves in his stomach. Other large plant-eating dinosaurs used a similar "trick".
modern birds, which are considered descendants of dinosaurs, also use stones for digestion.

Limbs and body structure of a stegosaurus:

Stegosaurs walked on four legs. Front legs stegosaurus were small and short compared to the powerful rear ones. Whole weight stegosaurus stood on its hind legs. The body had very unusual proportions due to the fact that the hind legs were much larger than the front ones, the back arched into a huge hump.

Although stegosaurus was a fairly peaceful creature, he was well protected. The entire body of the stegosaurus was dotted with numerous bone growths, which were located even at the throat.
Plates on the back stegosaurus set it apart from other dinosaurs. Initially, scientists assumed that this was a means of protection against predatory lizards, but after a closer study, this version was rejected.

It is known that red for animals is the color of danger. In combination with the mass of the body and the swinging from side to side of the spiked tail, the impression was impressive.
Stegosaurus could not only frighten, but also severely or even mortally injure the attacking lizard, attacking with tail spikes in unprotected paws and stomach.
In addition to protective functions, back plates stegosaurus served as a thermostat. In the morning when it's still cold stegosaurus turned its plates towards the sun and accumulated heat, like modern solar panels. In the heat, the plates removed excess heat, like radiators in modern technology.
Also, the color of the plates helped stegosaurus to compete with males during the mating season.

What in Latin sounds like "covered lizards" or "roof lizards" are a genus of herbivorous ornithischian herbivorous dinosaurs that existed on Earth during the breakup of the supercontinent Pangea in the Middle Jurassic (Fig. 1). The main number of diverse individuals assigned to this infraorder, scientists find in the deposits of the Kimmeridgian stage, and dates back to 155-145 million years ago. n.

Opening of the infraorder "Stegosaurs"

First more or less preserved Stegosaurus skeleton, namely - stegosaurus armatus, was discovered by professor Yale University Charles Marsh during excavations north of Morrison in Colorado back in 1877. Name "Stegosaurus" was given to the reptile on the grounds that its skeleton was covered from above with horny plates, which Marsh at first perceived as some kind of peculiar “roof”, vaguely resembling a tortoise shell, but at the same time located only on the back of a dinosaur, while the tortoise shell covers all of them whole body.

Subsequently, many varieties of stegosaurs were found on other continents of the planet, but scientists suggest that the ancestors of this infraorder are considered to be the ancient ovoid archosaurs that evolved in the African part of the supercontinent. Subsequently, from there they spread to South and North America, and already in the Jurassic period they settled along Pangea, which was not yet split in the northern part, into the Eurasian territory.

Rice. 1 - Stegosaurus

In our country, from time to time, paleontologists also managed to find fragmentary parts of the skeletons of these ancient creatures. But the most complete and well-preserved remains of a stegosaurus found in Russia to this day is the skeleton of an individual found in the Krasnoyarsk Territory among the Carboniferous deposits. jurassic, dated 170-165 million years ago. n.

The vicissitudes of the description of the stegosaurus

Several incidents are associated with the description of this genus of dinosaurs.

For the first time, the Stegosaurus of the Middle Jurassic period was described by the same professor of paleontology, Charles Marsh, literally in the same year in which this find happened.

At first, the stegosaurus was described by him as an ancient tortoise, since the scientist mistook the thyroid dorsal segments for a broken shell. In that district, excavations now did not stop, and archaeologists removed from the earth more and more remains of ancient animals, as a rule, belonging to the same variety and differing only in minor deviations in the structure of certain bones. Marsh worked tirelessly, and between 1879 and 1887 he was able to describe with varying success as many as six varieties of stegosaurs, sometimes based on only a few bones of one or another individual. Finally, in 1891, it was first published illustrated reconstruction of a stegosaurus, which Marsh has been working on for the past few years.

But in 1902, another no less prominent American paleontologist, Frederick Lucas, refuted Marsh's theory that the bone plates were a kind of underdeveloped shell for the dinosaur, which was a kind of “gable roof”. He put forward his theory that the shields, located along the spine, were pointed upwards, went in two rows along it from the head to the very tail, ending in massive spikes. Lucas also suggested that they served as an animal protection from flying lizards and dinosaurs, which were larger than the stegosaurus in height, in other words, they protected the animal's back from an attack from above. Less than a year later, Lucas changed his mind about the placement of the plates. If earlier he assumed that the plates went in two rows and in pairs to each other, now he claimed that they were arranged in a checkerboard pattern.

In 1910, another Yale University professor, Richard Lall, entered into a debate with him, arguing that the staggered order of the plates was caused by the displacement of the skeleton in the ground, that is, the unevenness of its occurrence in the rocks, as a result of which the shields paired with each other shifted, thereby forming " Lukasovsky" chess order. Participating in the first reconstruction of the stegosaurus skeleton at the Peabody Museum of Natural History, he insisted that the plates of the dinosaur be arranged exactly in pairs, in accordance with an earlier theory by Lucas.

Charles Gilmour continued the argument. In 1914, he made a statement that after analyzing a number of stegosaur skeletons and their occurrence in the soil, he found no evidence that the staggered arrangement of their plates was caused by rock shifting or any other natural causes and external factors and that it is, in fact, natural.

Rice. 2 - Stegosaurus Skeleton

In the end, Gilmour and Lucas prevailed in this almost half-century dispute, and subsequently, in 1924, stegosaurus reconstruction in the Peabody Museum has been modified in accordance with their theory, which is considered justified and generally accepted to this day.

Commonly accepted description of Stegosaurus

Infraorder Stegosaurus, in fact, in addition to the well-known representatives of the same name, it has two more varieties, namely, kentrosaurs and hesperosaurs. But, despite the fact that they differ slightly in their internal structure, skeletal structure and longitudinal dorsal growths, in general, in appearance, these individuals almost do not differ from each other.

For the most part, these herbivorous ornithischian representatives of the thyrophora reached 9 meters in length, 4 meters in height and weighed an average of 2 tons. Their jaws in front were equipped powerful beak, behind which there was a row of sharp small teeth. With their beaks, the animals broke off branches, with their teeth they ground them, and the greens on them, into porridge. Stegosaurus moved on four limbs, but occasionally they could also rise on their hind legs, for example, to pluck foliage from high-lying branches. At first, Marsh believed that the stegosaurus was a bipedal lizard, but later abandoned this assumption, although the dinosaur's forelimbs were indeed half as short and less developed than the hind limbs. It is possible that an offshoot of the ancient Early Triassic thyreophores, which became the progenitors of the infraorder Stegosaurs, initially preferred to move on their hind limbs, due to which the forelimbs began to decrease in size. But later, for some reason, the animals again preferred to stand on four legs.

Sacral thickening of stegosaurus

What is characteristic, with its impressive dimensions brain of stegosaurus weighed no more than 70 grams, which gave the right to Charles Marsh, the first to discover the skeleton of a stegosaurus, to conclude that these reptiles were exceptionally short in their mental development.

But upon further study of the skeleton in its sacral part, Marsh discovered a thickening of the spinal canal, which gave reason to say that this receptacle contained 20 times more brain tissue than the brain itself. From that moment on, theories were put forward, one more contradictory than the other. Most scientists came down to the assumption that it was this section of the spinal cord that was responsible for all the reflexes of the body, thereby greatly unloading the brain and leaving a wide space for thought processes.

Another theory was that since Stegosaurus was basically a massive and well-protected herbivore, there was absolutely nothing for it to think about, except that it needed to constantly chew, swallow, or sometimes stand on its hind limbs in order to get more attractive thread. For this, it is quite possible to get by with a 5-sanimeir brain. But for defense in a battle with predators, you would have to think, but this function was elevated to the category of reflex, for which the more extensive sacral brain.

Rice. 3 - Sacral thickening of a stegosaurus

But, as it turned out later, stegosaurs were not the only representatives of the animal world, whose spine is in this place contained a specific thickening. This anomaly was also found in the spines of many sauropods, and, most importantly, in the spines of modern birds, from which the scientists were able to conclude that this section contained a kind of glycogen body, the purpose of which is still unknown, but it is precisely established that it is by no means way cannot help vertebrates to think. It simply supplies the brains of animals with glycogen, but for what it is needed, there is no answer yet.

Appointment of plates and tail spikes

So it has not yet been clarified exactly why these ancient ornithischians needed plates. The theory put forward in early times, that plates of stegosaurus served as protection when attacked from above, it did not stand up to criticism, since the horn plates were very fragile, and in no way resembled defensive shields. It was not difficult for predators such as allosaurs to gnaw them, not to mention tyrannosaurs and other giant predatory theropods. In addition, when colliding with them, special damage could not be inflicted, since they were sometimes so blunt that they not only could not cut through the rough cellular skin of predators, but, conversely, from hard hit they could themselves be injured.

Some have suggested that predators, in view of their narrow mind, like real dogs, bite their teeth into everything that sticks out and into everything that is convenient to cling to. These very features were possessed by the dorsal plates of stegosaurus. While allosaurs and other predators ruffled their plates, the animal itself, spreading its limbs wide, led the defense with its spike-like tail, and after the defeat of one or several aggressive individuals, the predators allegedly simply retreated without causing any tangible damage to the stegosaurus.

Another assumption of scientists is based on the fact that plates were needed by stegosaurus for thermoregulation. It is possible that these porous horn formations could be completely saturated with a frequent network of small blood vessels, and thus perfectly suited to cool the body in extreme heat according to the principle of elephant or hare ears.

The fact that stegosaurs could quite effectively defend themselves and deliver lethal blows with their powerful spiked tail is evidenced by excavations. A considerable number of the same allosaurs with holes in the body have already been found, one to one suitable for the size and other parameters of the tail spikes of stegosaurus.

Habitats and food of stegosaurus

Scientists suggest that all ornithischians began to spread across the ancient continent of Pangea, which in the early Triassic was still a single supercontinent, from its African territory. Since the path to the European part, which was more distant at that time, was closed by the ancient ocean, ancestors of stegosaurs, early thyreophores were evenly distributed throughout Africa and South America and Antarctica, between which at that time there was no water separation. Further, the animals moved north into the territory North America and Europe, and then settled already throughout the Asian territory of Pangea. At the end of the Triassic, the beginning of the Jurassic, the separation of the continents from the main part of the supercontinent began, and in Cretaceous this has already acquired a pronounced global scale, which is why individual branches of animals subsequently evolved in their own way. In various continental parts, between which migratory routes were disrupted, more and more new varieties of stegosaurs are still found, although they often differ from the main branch only in their size and neck length.

Rice. 4 - Stegosaurus

So, in areas where low types of vegetation flourished, long necks were not needed for reptiles. It was not difficult to pick juicy foliage from the trees here. But in places where more tall trees, evolution had to work hard to produce reptiles with more long neck equipped with additional cervical vertebrae. One of these varieties was Miragayalongicollum, which lived in the Upper Jurassic on the territory of present-day Europe and, in particular, in Portugal, where the remains of these individuals were found. If the main varieties of stegosaurus number of cervical vertebrae varied from 12 to 13, then this species had as many as 17. This gives the right to say that Miragaya, having all the features of a stegosaurus, namely, horny dorsal shields and tail spikes, looked more like a diplodocus or on other sauropods.

The genus Stegosaurid differed mainly in that instead of shield plates, its back along the vertebra had two rows of long and massive spikes. In the case of Kentrosaurs, those spikes that are located only on the tail in ordinary stegosaurus go all over the body through the entire neck up to the back of the head, with the only difference being that they become slightly wider closer to the neck, which indicates that that earlier they most likely had the form of plates.

Rice. 5 - Kentrosaurus

(Fig. 5) reached a length of up to 5.5 m and at the same time had a relatively low height - only 1.5-2 m. In order to eat, according to scientists, he quite often had to stand on his hind legs, since the animal had a very short neck and short forelimbs. By the way, on the shoulder blades of the forelimbs, Kentrosaurs also had a massive spike-like formation.

Hesperosaurs

Another genus stegosaurus belonging to the stegosaurid family. Main distinguishing feature This variety consists in the fact that in this lizard the thyroid growths along the vertebra were only in one row, and although they were extremely massive, they were located much less frequently from each other than in the "chess" varieties.

Hesperosaurs reached an average length of 6.5 m with a total weight of more than 3.5 tons. These varieties lived in the North American part of Pangea, in what is now the state of Wyoming.

With the general diversity and abundance of stegosaurs in the Jurassic, it is very strange that these ornithischians are almost never found in the Cretaceous deposits. This gives reason to say that for some reason the overwhelming number of species of these animals died out at the border of the Jurassic and Cretaceous.

(155-145 million years ago), lived in the western United States (approximately the states of Wyoming and Colorado).

  • Found: Colorado 19th century
  • Kingdom: Animals
  • Era: Mesozoic
  • Type: Chordates
  • Group: Ornithischidae
  • Subgroup: Thyreophores
  • Class: Reptiles
  • Superorder: Dinosaurs
  • Infraorder: Stegosaurus
  • Family: Stegosaurids
  • Genus: Stegosaurus
    • A unique species of dinosaurs that is remembered for its unusual structure body. On the back and tail, it has a kind of plate resembling poplar or laurel leaves (depending on the age of the dinosaur).

    These dinosaurs were herbivores, moved on 4 legs, there are spikes and bone plates on the tail and back.

    What did they eat and what kind of life did they lead?

    Stegosaurs used only vegetation, because. their teeth didn't allow them to chew anything harder. Stegosaurus also swallowed whole stones, which they rubbed leaves in the stomach and helped improve digestion.

    Details about the structure of the body

    This dinosaur had excellent protection, solid bone outgrowths were located throughout the body, perfectly protecting its throat, legs and torso.

    Plates of various sizes are arranged in 2 rows on the back, the largest plates grew up to 1m. They were not particularly durable and were used more for intimidation than protection. When an enemy appeared, the plates were painted red (the color of danger), which scared off predators, and also helped to compete for females with other males of this species. In addition, the back plates were a thermostat that accumulated heat and removed its excess.

    But very sharp spikes were located on the tail, having struck with the tail, it could stun its attacker and even kill. The number of such spikes could be up to 4 pieces, and their length was from 70 cm to 1 meter.

    Dimensions

    It reached a length of 9m (the largest stegosaurus was found in Arizona - 9m 79cm)

    The height of the stegosaurus was no more than 4m
    Body weight - 5-7 tons

    Stegosaurus head

    The head was small, especially considering the enormous body of the dinosaur. The skull did not exceed 40 cm in length.
    The brain also did not differ in large sizes - the size of a walnut.
    Due to underdeveloped jaws, only tender leaves had to be eaten.

    limbs

    They moved on 4 legs, the front ones, in comparison with the hind ones, were short and not so powerful. All the load came on the hind legs.

    Video #2.

    Video #3.

    

    Photos and pictures

    (click to enlarge)

    The name "stegosaurus" means "roofed lizard". The first researchers thought that its dorsal plates were arranged like tiles on a roof: obliquely and slightly overlapping. Subsequently, paleontologists hypothesized that they were located vertically in two rows, and this position rather corresponded to their function: to regulate body temperature.

    The largest yet peaceful dinosaur was the Stegosaurus. Stegosaurus had one very interesting feature in the structure of the ridge - there were two rows of triangular plates on it. Most likely, these plates served to protect against enemies and to regulate body temperature: under the sun's rays, they accumulated heat, but if the body temperature became too high, then a light wind or shade was enough - and the same plates began to give off this heat.

    What did a stegosaurus look like?

    The stegosaurs were really huge, they could reach 9 meters in length, and on the tail the stegosaurus had long spikes (on the order of a meter), with which they could defend themselves from predators.
    Stegosaurus was a herbivore, for this reason his teeth were weak and could only chew plant foods. The head was small compared to the massive body.

    A unique genus, recognizable by scientists even at a distance. Why? is the accepted Latin name. But it comes from two Greek words: roof (stegos) - lizard (sauros). The animal received it thanks to the main distinguishing feature- the presence of a number of large leaf-shaped plates on the back. On the background large body the small head is especially contrasting.

    Time and place of existence

    They lived at the end of the Jurassic period about 155.7 - 145.5 million years ago. All species are found in the closer to the west of the United States (Colorado and Wyoming).

    At that time, it was dominated by warm, almost tropical climate- ideal for such herbivorous dinosaurs as a stegosaurus. The vegetation that grew on the continent, at first glance, resembled modern a tropical forest, however, today's plant species did not exist at that time. So, there were no flower plants. Everywhere, next to the ferns and coniferous trees, ancient palm trees grew, which, in their appearance, resembled modern ones.

    The drawing by Zdeněk Burian is one of the reconstructions in the habitat. There are clear footprints in the wet soil, which could have been used by predators such as Allosaurus or Ceratosaurus to detect stegosaurids.

    INTERESTING INFORMATION. DO YOU KNOW THAT…

    • IN Western Europe Fossilized remains of a relative of the Stegosaurus have been found.
    • Obviously, stegosaurs lived for a short time in the Jurassic period. The remains of these dinosaurs are found only in the upper layers of rocks.
    • Some modern reptiles their appearance They look like miniature copies of extinct dinosaurs.
    • The lizard, which lives in Africa, has spikes on its head and body, similar to those that were in a stegosaurus. However, this lizard is 60 times smaller than a Stegosaurus, and its length reaches only 60 cm.

    Types and history of discovery

    Three types of stegosaurs are now considered generally recognized. The rest either did not find sufficient evidence, or were included in the main ones. Stegosaurus armatus was described famous professor G. Marsh back in 1877. It was also one of the first officially found remains of dinosaurs in general. They were excavated north of the small American town of Morrison. Stegosaurus stenops And Stegosaurus longispinus were smaller.

    body structure

    The body length of this creature reached 9 meters (comparative dimensions are shown in the figure). The height is up to 4 m. The representative weighed 4.5 tons.

    On the back was a whole series of plates. The discoverer of the skeleton, G. Marsh, erroneously assumed that they were connected to each other like tiles covering the back. However, it is now known that they were located perpendicular to the body of the animal. Namely, two parallel rows at some distance from each other in such a way that the sheet of one row was opposite the gap of the other. There was also a gap between the "leaves" of the stegosaurus. Really handsome - do not say anything.

    The purpose of the plates is still not exactly known. The discoverers first speculated that the plates protected him from attacks. predatory dinosaurs. However, a detailed study of scientific community in 1970 showed that they were fragile and did not pose any physical danger. Yes, and the attackers could easily hit the side of the body. Thus, now there are three options: defensive and two peaceful.

    The first suggests that the plates were painted in bright colors (and maybe the whole Stegosaurus). Appearing in such a prickly painted form near a predator, he could scare away or at least puzzle the offender. If the second happened, then the tail came to the rescue, with which it was possible to deliver an aimed blow.

    The second option - each plate was pierced by large blood vessels. This design of the circulatory system made it possible to cool the body in case of extreme heat and, conversely, quickly accumulate heat on cold mornings. After all, the Stegosaurus was a cold-blooded reptile.

    The third case - the shape and color of the plates may have played a significant role in building relationships in a group of animals. Moreover, they could be used by males in marriage games. There is also Robert Becker's suggestion that stegosaurus could even move bone decorations up and down. Such nine-meter peacocks moving the plates and filling them with blood more than compensate for grace with assertiveness. In fact, all three assumptions could be true - it was a universal tool.

    Separately, it is worth mentioning the tail. At the end of it, sharp spikes were attached, which, unlike plates, could cause significant damage to a careless predator. The blow of a powerful tail was able to stun and leave even a mortal wound.

    Stegosaurus skeleton

    The photo shows museum exhibits of the species Stegosaurus stenops.

    Skull on close examination of the same species.

    The head was small, especially considering the enormous body of the dinosaur. The skull did not exceed 40 cm in length.
    The brain also did not differ in large sizes - the size of a walnut.
    Due to underdeveloped jaws, only tender leaves had to be eaten.

    Appointment of plates and tail spikes

    So it has not yet been clarified exactly why these ancient ornithischians needed plates. The theory put forward in early times that plates of stegosaurus served as protection when attacked from above, it did not stand up to criticism, since the horn plates were very fragile, and in no way resembled defensive shields. It was not difficult for predators such as allosaurs to gnaw them, not to mention tyrannosaurs and other giant predatory theropods. In addition, in a collision with them, special damage could not be inflicted, since they were sometimes so blunt that they not only could not cut through the rough cellular skin of predators, but, on the contrary, they themselves could be injured from a strong blow to them.

    Some have suggested that predators, in view of their narrow mind, like real dogs, bite their teeth into everything that sticks out and into everything that is convenient to cling to. These very features were possessed by the dorsal plates of stegosaurus. While allosaurs and other predators ruffled their plates, the animal itself, spreading its limbs wide, led the defense with its spike-like tail, and after the defeat of one or several aggressive individuals, the predators allegedly simply retreated without causing any tangible damage to the stegosaurus.

    Another assumption of scientists is based on the fact that plates were needed by stegosaurus for thermoregulation. It is possible that these porous horn formations could be completely saturated with a frequent network of small blood vessels, and thus perfectly suited to cool the body in extreme heat according to the principle of elephant or hare ears.

    The fact that stegosaurs could quite effectively defend themselves and deliver lethal blows with their powerful spiked tail is evidenced by excavations. A considerable number of the same allosaurs with holes in the body have already been found, one to one suitable for the size and other parameters of the tail spikes of stegosaurus.

    Nutrition and lifestyle

    Stegosaurs cut low vegetation with adapted teeth. However, there are suggestions that grass and shrubs were not the only food. The hind limbs of the dinosaur were much larger than the front ones, so there is a possibility that he could stand on them (on a short time) to pluck the lower branches of trees.

    It is a symbol of the American state of Colorado, where it was first excavated in the 19th century by the pioneers of paleontology.

    In culture

    • Stegosaurus appeared in the movie "Jurassic Park 2: lost World”, then there was a small scene with a stegosaurus in the background in Jurassic Park 3.
    • IN computer game"ParaWorld" stegosaurus either roams lava-scorched glades and savannahs, or transports people and weapons. Also available in Jurassic Park: Operation Genesis.
    • Stegosaurus is involved in documentaries BBC "Walking with Dinosaurs" (series "Time of the Titans") and "The Ballad of Big Al".
    • Several stegosaurus are featured in the Jurassic segment of the Discovery movie "When Dinosaurs Roamed America". One of them digs a hole during a drought, trying to get to the aquifer, a couple of others are attacked by a ceratosaurus. Having fought off a predator with the help of a spiked tail, the male shows his brightly colored dorsal plates to the female, but she is not ready for mating. A few days later, he repeats the mating ritual, this time successfully.
    • Also, the most modern and colorful image of the stegosaurus turned out in the "Fight Club of the Jurassic Period" ("Lost Worlds").
    • Stegosaurus can be farmed in Zoo Tycoon 2 Extinct Animals.
    • The Stegosaurus appears in Arthur Conan Doyle's The Lost World.
    • He appears in Jurassic World: The Game, where he is somewhat underestimated, as he loses to the Spinosaurus, although in reality he would be stronger than him. However, it is equal in strength to the Allosaurus, which corresponds to reality.

    Video

    Sources

      http://dinosaurs.afly.ru/stegosauria/48-stegosaurus