While the history of dinosaurs remains a fascinating subject, we now know a lot more about these creatures that once walked the world. These impressive animals by their size lived during a large period of the Mesozoic or Secondary era, from 250 million to 65 million years before our era. Several hypotheses have been made regarding their extinction, but this time we will focus on the phenomena that contributed to their appearance on Earth.
What is a dinosaur ?
Dinosaurs were impressive animals that still arouse our curiosity today. It was an English paleontologist named Richard Owen who coined the word “dinosaur” in 1842, thus designating very large bones whose appearance was roughly similar to that of lizard bones. The word dinosaur comes from the Greek “Sauros”, which means “lizard/reptile” and “Deino” which means “terribly large”. These giant reptiles had 4 legs located under their body, unlike the legs of lizards which are on the sides. Researchers have also identified nearly 1,000 species of dinosaurs. They also claim that Diplodocus and Tyrannosaurus Rex would not have existed at the same time. The first would have died out long before the appearance of the Tyrannosaurus.
From the Big Bang to the Age of Dinosaurs
To better understand the origin of dinosaurs, it is necessary to focus on the chronology of evolution from the Big Bang to the era of the first dinosaurs on Earth. So, about 14 billion years ago, the universe was formed after the Big Bang. It was following this explosion that galaxies, stars, planets were formed… The solar system and its planets appeared 10 billion years ago. Our planet, meanwhile, was formed a little later, 4.6 billion years ago. This was followed by the appearance of prokaryotic cells 4 billion years ago and photosynthesis 3 billion years ago. It took several millennia for multicellular life to make its way to the or Ediacara fauna, 600 million years ago.
Evolution continued and more "complex" animals appeared 550 million years ago. Then came fish and proto-amphibians, then land plants. Insects and seeds appeared almost at the same time, 400 million years ago. As for the first amphibians, they lived 360 million years ago. Then came the reptiles, 300 million years ago and finally the famous dinosaurs, about 250 million years ago.
When did the first dinosaur appear ?
The very first dinosaurs appeared during the Triassic, following a major biological crisis, 230 million years ago. They were mainly small bipeds and were called theropods. Like the reptiles that preceded them, they were oviparous and therefore laid eggs. The largest dinosaurs during the Triassic were barely 6 meters long: Prosauropods and Plateosaurs. The latter cohabited with the 30 cm high Lesothaurs, the Heterodontosaurs or the Herrerasaurs. There were also Procompsognathus which were less than 1 meter long and which were fond of lizards and insects.
The Jurassic period
200 million years ago began the Jurassic period which saw the evolution of dinosaurs. These reptiles diversify into different species. It was also at this time that the dinosaurs described as “terribly large” appeared and that the Prosauropods disappeared. The Diplodocus and the Seismosaurus, for example, lived during this period. These animals were particularly large, even compared to their congeners.
Then came the Stegosaurus which is recognizable by its spiky back. As for the carnivores, they became very serious predators and were not long in being as impressive as the majority of the herbivores. This is particularly the case of the Torvosaurus which was 11 meters long, the Carmataurus, the Ceratosaurus or the famous Dilophosaurus immortalized in a film which borrows part of its name from this period of history.
The Jurassic era, which lasted 55 million years, also saw the appearance of the first feathered dinosaurs, including Archeopteryx. Recent studies in this area suggest that they are the ancestors of birds or cousins of birds.
The Cretaceous period
145 million years ago, the Jurassic gave way to the Cretaceous period. Dinosaurs such as Tyrannosaurs cohabited with Triceratops. A seabird has also appeared: the Ichthyomis. He was an excellent swimmer who couldn't really fly, but had teeth. It was also during the Cretaceous period that Laurasia and Gondwana, which had begun to fracture in the Jurassic, disappeared to make way for the continents.
The dinosaurs were scattered and species developed on each of the continents. The reign of the dinosaurs ended 65 million years ago, following a huge cataclysm about which the hypotheses are multiple: meteorite, supervolcano, both. Ammonites, marine reptiles and Pterosaurs disappeared during the Cretaceous. Among the dinosaurs and their cousins, only certain species of birds survived.
The Paleogene period
According to researchers, not all dinosaurs died out during the Cretaceous. Some were even able to survive well beyond that. The end of the Cretaceous indeed marks the beginning of the Paleogene during which giant birds (cousins of the dinosaurs) as well as mammals began to colonize the Earth. This period lasted 23 million years.
The Neogene period began 23 million years ago and has continued until now, traversed by the ancestors of modern mammals and birds. So the dinosaurs disappeared at that time? No. To date, ornithologists list more than 10,000 species of birds. Most are descendants of dinosaurs that have evolved according to the environment. This is the case of the ostrich, the South American hoatzin, or the penguins.
As they evolved, some developed swimming abilities, while others lost their ability to fly. We can therefore say that these birds are the "dinosaurs of our time".
How long did a dinosaur live ?
The longevity of dinosaurs mostly depends on their size, as those that were less than 1 meter tall lived six years or less. In contrast, large dinosaurs had very good life expectancies. Some could even live to be seventy years old. To find out, the researchers relied on fossilized bones.
Scientists even go on to claim that herbivores lived much longer than carnivorous dinosaurs. This is explained by the abundance and diversity of food for herbivores at that time. As for the famous Tyrannosaurs which were very large predators, they lived about 30 years. The Brontosaurus, on the other hand, which were herbivores weighing more than 30 tons, could live for a very long time, around 80 years.
What is the flavor of dinosaur meat ?
Even though prehistoric humans and dinosaurs never lived together , many of us wonder what dinosaur flesh might have tasted like. We can rely on the assumptions that crocodiles and birds are descendants of dinosaurs. The flavor of dinosaur meat could therefore, perhaps, be similar to that of crocodile meat.
If you've never had the opportunity to taste crocodile meat, know that the taste is quite similar to chicken, but the consistency is strangely reminiscent of fish.
Could humans have cohabited with Tyrannosaurs ?
As a predator, Tyrannosaurus was feared by its peers. And fortunately humans did not live with this animal, because they certainly could not have survived. Paleontologists estimate its maximum running speed at 29 km/hour. So unless you were a middle-distance champion, the men would have had little chance of escaping him.
What colors were the dinosaurs ?
Even for paleontologists, it is difficult to accurately determine the colors of dinosaurs. We can always base ourselves on the colors of the birds and crocodiles which are supposed to be the cousins of the dinosaurs, and make conjectures taking into account the environment in which they evolved, with its flora and its minerals. Indeed, despite evolution, some colors could have been transmitted from generation to generation.
In recent years, however, electron microscopes have enabled some teams to identify tiny fossilized pigments trapped in the remains of hair, and the colors identified seem to be very varied: yellow, red, fawn!
Which were the largest dinosaurs and which were the fastest ?
By studying the fossilized bones, paleontologists were able to establish the size of the dinosaurs. For example, the Brachiosaurus was the tallest dinosaur since its size was similar to a four-story building. The Argentinosaurus holds the prize for the heaviest dinosaur, because it weighed between 80 and 100 tons, and this same dinosaur was 35 meters long! On the other hand, the Anchiormis embodied quite the opposite, this feathered dinosaur considered as an “almost bird” was particularly small and light.
And despite some popular beliefs, the Velociraptor is not the fastest dinosaur, because the one who holds the record for speed is the Dromiceimimus. The latter is 3 times faster than the man. In another register, it is the Ankylosaurus which is the slowest dinosaur.
Be aware that when it comes to reproduction, sauropods laid the largest eggs. The Troodon was apparently the one with the biggest brain, but no one knows if it was intelligent or not. Conversely, Stegosaurus was the dinosaur with the smallest brain. Indeed, even after their extinction, the dinosaurs have not finished surprising us.
Who was the Kamuysaurus japonicus discovered in Japan ?
Japanese researchers have reconstructed the skeleton of an 8-meter-long dinosaur. It is certainly the largest dinosaur discovered in this archipelago. Also according to experts from the University of Hokkaido in northern Japan, the bones are 72 million years old. This species comes from the hadrosaurids which are distinguished by their duck-like beak. The dinosaur discovered in Japan was therefore probably an herbivore that lived during the Cretaceous.
The excavations took place gradually since the tail of the dinosaur was discovered in 2013. The entire skeleton was reconstituted little by little, over the years. Japanese researchers say it was a 9-year-old dinosaur that weighed nearly 5.3 tons. The results of the study were published in Scientific Reports. For the Japanese, this dinosaur is a “dragon god” hence its name: Kamuysaurus japonicus.
This discovery thus made it possible to update the existence of another species of dinosaurs which would have lived in Japan or in Asia. The researchers are sure, this kind of dinosaur would have evolved independently of the others. It has indeed been able to survive in coastal areas and has adapted to its environment. Despite the marine sediments, the bones were very well preserved. This discovery was able to confirm that some dinosaurs preferred regions bordering the oceans. They have diversified and evolved at their own pace.
Researchers at Hokkaido University hope to unearth even more bones in this region, which is basically an unusual environment for dinosaurs. The Japanese are therefore continuing research in the coastal areas and around the site where the bones of Kamuysaurus japonicus were discovered.