Dinosaurs are one of the best known prehistoric groups of animals. Huge reptiles are interesting not only to paleontologists, but also to people not related to science. What were they, how did they become extinct and did all of them die? Find all the answers here!
Definition of dinosaurs
The term “dinosaur” was coined by British paleontologist Richard Owen in the 1840s. Studying the remains of these extinct animals prompted him to create a name that is a combination of two words from ancient Greek – deinos (scary) and sauros (lizard). While emphasizing the majesty of these creatures can be considered a success, the name itself is somewhat untrue.
Contrary to their name, dinosaurs are not lizards like modern e.g. komodo dragons. What they have in common with them is the fact that they belong to a group of reptiles. Like most ancient and modern members of this group, dinosaurs laid eggs. They were distinguished from other reptiles by their warm-bloodedness and the rapid metabolism associated with it.
Not all of them were “terrible” in the sense – big and bloodthirsty. Indeed, many species are large reptiles with large body sizes. Especially the Jurassic era has grown into colossi such as the diplodocus weighing about 50 tons and probably growing up to 35 m in length.
Nevertheless, not all dinosaurs were large. For example, the compsognathus was 1.2 meters long at most. There were even smaller species, like the one discovered in China that grew only up to 48 cm.
What else distinguishes dinosaurs from other reptiles is their terrestrial lifestyle. This applies not only to modern creatures, but also to those with whom these animals shared the world. Dinosaurs are not the great sea and flying reptiles of the Mesozoic era. The ones living in the oceans, like ichthyosaurs, plesiosaurs and mosasaurs , or flying pterosaurs are separate orders of reptiles.
When Did Dinosaurs Live?
Dinosaurs are a symbol of the Mesozoic era. It is divided into three periods – Triassic, Jurassic and Cretaceous. The history of these reptiles begins in the Triassic 237 million years ago. They achieved their evolutionary success by occupying empty ecological niches after the greatest extinction in history, which affected 95% of species and ended the Palaeozoic era.
In the early Triassic, dinosaurs were not yet the dominant group of animals. However, they underwent rapid species diversification. In the next period, the Jurassic (201–145 million years ago), this allowed them to become the main group of land animals.
When the dinosaurs lived, other land animal clusters and orders of reptiles did not have much opportunity to develop. The chance for them appeared only at the end of the Cretaceous (145–66 million years ago). Then the dinosaurs became extinct, repeating the fate of the creatures they replaced in the Triassic.
The cause of the extinction
Scores of paleontologists have wondered for decades how the dinosaurs died out. The most likely cause of Cretaceous extinction is the impact of the asteroid Baptistina 66 million years ago. Its length is estimated at up to 10 km.
To prove the truth of this theory we have two pieces of evidence. The first is the 180 km diameter Chicxulub crater near the Yucatan Peninsula in Mexico. The second is unnaturally large deposits of iridium found all over the world in rocks that mark the boundary between the Mesozoic and Cenozoic. This element is rare on Earth, but it is often detected in asteroids.
The impact of such a large celestial body caused an explosion of great force. An explosion with the power of thousands of atomic bombs led to five more disasters.
The first was the creation of the shock wave which led directly to the death of the animals. With it, a second threat has arisen – a sharp rise in temperature to levels that terrestrial organisms cannot survive.
The third result was a gigantic tsunami. Even today it would be catastrophic. It was even more devastating then. The reason is the system of continents. As there were only two (Laurasia and Gondwana), most parts of the globe did not encounter obstacles that could crash into (other continents). The lack of natural barriers on most of the globe is possible for the waves to accelerate.
Such great energy experienced by the earth’s crust led to earthquakes. The result was the destabilization of tectonic plates and increased volcanism. As a result of these events , large amounts of hot, poisonous gasses were released into the atmosphere.
The final result of the impact was that large amounts of dust were thrown into the atmosphere, which limited access to sunlight. A phenomenon similar to nuclear winter took place, and hence a cooling down of the climate. It may have been several years before the dust settled. For dinosaurs accustomed to tropical conditions, the cold climate was unbearable.
The closest living relatives of dinosaurs
The Cretaceous Extinction led to the extinction of many groups of animals. Among them were dinosaurs, though not all. Other reptiles also disappeared – pterosaurs, plesiosaurs, mosasaurs. Other groups of animals also did not survive, including some species of mammals, amphibians, birds and molluscs (e.g. ammonites). This extinction affected all continents and oceans on Earth.
What has survived? Even some dinosaurs, but not those that are usually the first object of associations. Birds that come from the same evolutionary lineage as the reptilian dinosaurs survive. It is for this reason that today we no longer talk about the extinction of dinosaurs, but about the fact that dinosaurs did not survive. Other living relatives of dinosaurs today are crocodiles.
Selected species of dinosaurs
During 171 million years of existence, dinosaurs have developed into thousands of different forms. There were large and small creatures among them, sometimes with fanciful shapes. Some of them are known only to paleontologists. Several species, however, managed to make a name for themselves.
One of the dinosaurs that lived at the end of the Cretaceous. It was 8–9 m long, 2–3 m high and weighed up to 12 tons. The oldest remains found are 68 million years old. It was a herbivorous animal. Triceratops lived in herds. Their unique features were 3 horns and a bone structure (ruff) covering the neck. Its function is unknown. It could be used as a defense against predators. It is also possible that it came in handy during the mating season.
This species lived at the same time as the triceratops. T-Rex is the main predator of this period, which also hunted large herbivores, such as triceratops. His body structure remains a mystery to this day. The average weight of individuals is estimated at 4.5–8 tons, and their length is up to 12 m. He moved on two limbs. Its forelegs were very small, but it is not known why.
During the Jurassic period (155–145 million years ago) there lived a T–Rex-like Allosaurus. Although he looked like him, he was not his ancestor. Allosaurus lived in the times of the greatest herbivores. They were large (even 8 meters long), but much smaller than their victims. For this reason, it is believed that they could hunt in packs like today’s wolves. This thesis is supported by the bones of many Allosaurus found in the same place.
One of the largest, if not the largest dinosaurs in history. It lived 97–93 million years ago. It looked like other great herbivores. It had a long neck and tail, and walked on four legs that supported a bulky body. Like the other great sauropods, it had a small head. This disproportion is a characteristic feature of many representatives of this dinosaur infra-order. Based on the fragments of the skeleton, it is estimated that it measured over 30 m and weighed about 70 tons.
For a change, representatives of this species were rather small. Velociraptor was on average 1 m high, up to 1.7 m long and weighed about 20 kg. It was a predator. Due to its size, it hunted for smaller dinosaurs and young individuals of large species. Its skeleton shows many features similar to modern birds. It was also covered with feathers. Velociraptors lived 75–71 million years ago.
The best movies about dinosaurs
When you think about movies in which the heroes are dinosaurs, it is impossible not to mention the Jurassic Park series. This best-known film went down in the history of cinema for good. One of the classics is also Million Years BC from 1966.
In addition, many other films of different genres have been made. The Good Dinosaur and Ice Age: The Age of the Dinosaurs are interesting suggestions for children. A documentary on this subject that is worth recommending is Wandering with the Dinosaurs.
Not necessarily successful productions are also very popular. Lovers of such cinema may be interested in the horror movie Dinosaur Attack. Rated 3.1 / 10 on IMDb is best recommended for B-movie fans.
Dinosaurs have fascinated people for decades. Their often remarkable size and sudden extinction have made them an important part not only of science, but also of mass culture. The discoveries of other species push the boundaries of how big some of them were. Their research makes it possible to discover the history of the Earth, exposing its extraordinary species richness.