People have been finding giant bones since ancient times. Until the 19th century, they were considered the remains of ancient giants or magical dragons. Today, every child knows that millions of years ago, huge dinosaurs roamed our planet. They could be up to 12 meters tall and weigh up to 100 kg. But when did the first dinosaurs appear and why did they suddenly disappear, leaving behind many mysteries?
Studying fossils
It is known that giant lizards inhabited all continents of the Earth, including Antarctica. It is not surprising that people have discovered their fossilized remains throughout their existence. In this regard, it is impossible to name the first dinosaur found.
Collection of bones for scientific study was first started by the Englishman W. Buckland at the end of the 18th century. The professor of geology could not figure out who they belonged to. The French naturalist J. Cuvier guessed in 1818 that these were the remains of huge lizards. In 1824 a report was presented in Londonabout the discovery of "antediluvian" animals called megalosaurs.
In 1825, the doctor Mantel examined the teeth of an unknown animal, which had a length of 4-5 cm. They looked like the teeth of an iguana, so the animal was called an iguanod. In 1837, Professor G. Meyer found the bones of a new dinosaur in Germany and named it Plateosaurus (plain lizard). Only in 1847 did the London professor R. Owen prove that all the finds belong to the same species of reptiles. The group was called dinosaurs, or "terrible lizards".
Characteristics
Before talking about the first dinosaurs, let's look at the distinctive features of this amazing group of animals. All of them are very different from each other. Some lizards were the size of a chicken, while others were as large as whales. Some ate grass, others led a predatory lifestyle. Someone moved slowly on four legs, someone quickly ran on two limbs.
However, there are common properties:
- All dinosaurs were terrestrial.
- Their limbs were located below the body, and not on the sides, as in other reptiles. The legs were straight. This made the animals very mobile.
- On the skull behind the eye sockets there were two temporal cavities (other reptiles have one). Due to this, dinosaurs acquired a powerful moving jaw and keen hearing.
Lifetime
The Mesozoic era is considered to be the era of dinosaurs. It is divided into three periods: Triassic (252-201 million years ago), Jurassic (201-145 million years ago).ago) and Cretaceous (145-66 million years ago). The first dinosaurs on Earth appeared 230 million years ago. At that time, there was only one giant continent, Pangea, with a hot and dry climate.
In the Jurassic period, the continents moved apart, seas formed between them. The climate became humid, deserts were replaced by tropical forests. In such favorable conditions, dinosaurs took a leading position and reached gigantic sizes. But their real heyday came in the Cretaceous period.
The history of the species ended abruptly. In rocks 70 million years old, many bones and teeth of dinosaurs are found. However, after 5-6 million years, according to paleontologists, the huge lizards completely died out.
Immediate ancestors
But back to the very beginning. Life originated in water. 300 million years ago, the first vertebrate reptiles got ashore and began to lay their eggs on land. At first they were small in size (about the size of a lizard), but over time, large predators the size of a crocodile (thecodonts) appeared. Some of them (particularly Ornithosuchus) were able to run on their hind legs.
The ancestors of the first dinosaurs were archosaurs, which changed the arrangement of the limbs. They did not crawl on widely spaced paws, but moved on straight limbs. A striking example is the lagosuch, which resembles a rabbit in its size and structure of its hind legs. The front animal could capture the insects that it fed on. The tail of the Lagosuch was long. Most likely, the staurikosaurus originated from it, the remainswhich are 228 million years old.
The very first dinosaur
The first lizards were predators and belonged to the group of theropods (in translation - "beasts"). They ran on two legs, had clawed toes on their front paws and could gather food with them. The earliest dinosaurs found are:
- Eoraptor. This is the oldest species found in Argentina (from 228 to 235 million years ago). The length of the animal is no more than a meter. It is comparable in size to a dog. Approximate weight - 10 kg.
- Stavricosaurus. It had a length of just over 2 m, a height of about 80 cm. The weight of the animal reached 30 kg. The lizard was very fast.
- Herrerasaurus. This is the most primitive dinosaur about 4 m long. Its weight ranged from 200 to 250 kg. The predator preyed on lizards, small reptiles, as evidenced by sharp, curved teeth.
The advent of herbivorous dinosaurs
Following the predators, lizards arose, eating plant foods. Most of them were quite large. The first vegetarian dinosaur was Plateosaurus, with a long neck and pear-shaped torso. The length of the animal ranged from 6 to 12 m. The weight reached 4 tons.
The giant moved on four legs. A powerful pelvis and muscular tail allowed the Plateosaurus to stand on its hind legs, as a modern kangaroo does, and reach the crowns of ferns 5 m high.
Lifestyle
The period of the first dinosaurs ended with their complete victory over the restspecies that inhabit the planet. Such bizarre creatures have never lived on Earth before. The variety of shapes and sizes still surprises scientists.
All dinosaurs can be divided into two groups: carnivores and herbivores. The first ones ran on two powerful legs and had a flexible tail. Most of the predators reached a length of 2 to 4 meters. But there were also giants like tyrannosaurus and giganosaurus up to 15 m long and weighing up to 8 tons. They hunted the largest herbivorous dinosaurs.
The latter preferred to move in herds in order to be able to protect the cubs. Many of them had horns, bone growths, or tail spikes to help them endure the fight. Herbivorous dinosaurs had different sizes, which allowed them to eat leaves from different tiers. The largest are considered brachiosaurs and diplodocus up to 40 m long and weighing more than 100 tons. They lived on land and were extremely slow.
Baby dinosaurs hatched from eggs. Their parents fed them in the nests, as birds still do. Many scientists believe that the largest of the dinosaurs were viviparous. After all, the largest of the eggs found has a size of only 30 cm. And not all species could stay in one place for a long time to protect eggs and cubs.
Sudden death: hypotheses
Nobody has yet given an exact answer to the question of why all dinosaurs disappeared from the planet 65 million years ago. After all, the crocodiles, snakes, turtles, lizards, mammals and birds that lived at the same time still exist. The most plausible version is about changing the familiar ecosystem.
She could be called:
- The fall of a large asteroid, which led to the activation of volcanoes and large dust emissions. The sun's rays stopped entering the Earth's atmosphere, many plants died, and a cold snap set in.
- Evolution, during which the gymnosperms, which mainly fed on herbivorous dinosaurs, disappeared. They were replaced by flowering species, but the giants were unable to adapt to a new type of food. After a sharp decline in their numbers, predatory dinosaurs began to die out.
- The movement of the lithospheric plates, which led to a change in currents in the ocean and a sharp cooling.
- A supernova explosion that sent harsh cosmic radiation to the planet.
It is unlikely that we will know how it was in reality. In any case, the first dinosaurs marked the beginning of a glorious era that lasted 150 million years. As a memory of her, we are left with huge bones of extinct giants and many mysteries that excite the imagination.
