Dinosaurs were the overlords of the Mesozoic Earth, their huge bodies shrouded all corners of the land, and other animals encountered them and could only look at the wind and flee. However, when we look back at the ancestors of dinosaurs, we will find that they are far less strong than later, and before the Mesozoic Era, the earth overlord had another person. How did the dinosaurs complete the transformation of the animal kingdom on earth and ascend to the throne of supremacy?
The early dinosaurs were all small guys
Humble dinosaur ancestors
In the Santa Croce region of central Poland, paleontologists have found many animal footprints. Among these footprints, they identified some that were very similar to the footprints of dinosaurs. If the animal that left these footprints is not a dinosaur, it must be a dinosaur and its similar species. The footprints were small, and in the muddy soil of that year, the three toes in the middle of the animal's paws were crammed together. These animals are also strange when walking, because the front legs are short, and when the hind legs step out, they will step in front of the front leg footprints.
These dinosaur-like footprints appeared at three excavation sites at the time of the junction of the Permian and Triassic periods, about 246 million years ago. In two of the more ancient excavation sites, paleontologists judged by footprints that the animals were walking on four legs. But at a slightly later third excavation site, the animals became slightly larger and were able to stand up and walk on two feet. The earliest dinosaurs currently accepted by paleontologists, who lived in Argentina 230 million years ago, were small, bipedal animals. So the footprints found at this third excavation site may really be left by more ancient dinosaurs.
This kind of dinosaur-like footprint is actually very rare. Of the fossil footprints found at excavation sites, only 2 to 3 percent were left by this dinosaur-like animal, and a large number of other footprints were left by reptiles and amphibians such as lizards and crocodiles. This shows that the ancestors of the dinosaurs were just ordinary members of all the sentient beings at that time, far less beautiful than later.
Survived the Cataclysm
The emergence and rise of dinosaurs begins with the gratitude of one of the largest disasters on Earth.
At the end of the Permian period, 252 million years ago, life on Earth underwent a tragic extinction, in which at least 90% of living things disappeared. Paleontological fossils show that the terrestrial animals on the pangu continent, a supercontinent in the southern hemisphere of the Earth at that time, underwent a major reshuffle. Among the losers in this shuffle were some chubby lizards, such as dipodonts, which had short tails and turtle-like heads, which were common animals at the time.
There are also winners in the shuffle, such as Cyrusosaurus, which are plant-eating animals and are closely related to dinosaurs. In tanzania in today's Africa, paleontologists have discovered a species of Cyrillic dragons, ashleidosaurus, which lived in the middle of the Triassic Period, 245 million years ago, was about 1 meter long, had slender limbs, and weighed about 10 to 30 kilograms, equivalent to the size of a dog.
Restoration of Nyasaron
Fossils of an animal called Nyasaurus have also been found in the same area, which paleontologists believe is either the earliest dinosaur or the closest relative to dinosaurs. It was somewhat larger than ashleosaurus and lived 230 million years ago.
These two animals found in Africa reveal some information about the birth of dinosaurs and the period. For example, dinosaurs may have been the first to emerge from the African continent, and their ancestors survived the brutal test of the great extermination 252 million years ago, perhaps because they were smaller and more agile. After the Great Extinction event swept away a large number of other animals, the ancestors of the dinosaurs clearly had a once-in-a-lifetime opportunity to flourish.
Another catastrophe swept away the enemy
However, even in the Triassic period after the Great Extinction, the dinosaurs were not able to dominate the earth, and the overlords of the earth during that period were the ancestors of crocodiles, such as pseudo-crocodiles. The animal was large and probably preyed on certain dinosaurs, forcing them to evolve defensive body structures such as strong armor and a powerful tail that could strike at incoming enemies.
If there were no accidents, the small dinosaurs at that time could not shake the status of these crocodile ancestors. Interestingly, the heavens seem to have intended to put the dinosaurs on the throne of the earth's overlords, and just 200 million years ago, during the border period from the Triassic to the Jurassic, another major disaster struck. In this biological extinction, the pseudo-crocodiles suffered a huge blow, and all the other species suffered with the exception of a very small number of crocodiles that survived the disaster and evolved into today's crocodiles.
Compared with pseudo-crocodiles, although the dinosaurs were small at that time, their mobility was obviously stronger, and their respiratory system was stronger, so the dinosaurs once again survived the Great Extinction Event, and in the following Jurassic ushered in the great development of species, and ascended to the throne of the overlord of the earth in one fell swoop!
Dinosaurs rise thanks to volcanic eruptions?
What kind of catastrophe happened on Earth 200 million years ago that made the war between dinosaurs and crocodile ancestors around global hegemony biased in favor of the dinosaurs?
The great eruption of the volcano cleared the way for the rise of the dinosaurs
In the 200 million-year-old lake bottom sediments of new England, scientists have found leaf wax, pollen, wood and other plant materials that were probably carried into the lake by magma during a violent volcanic eruption, without burning out of the residue. And at that time, the carbon component contained in the atmosphere increased significantly, although volcanic eruptions did spew out some carbon-containing gases, but at the same time, fires caused by volcanic eruptions would also cause forests and fossil fuels to burn in large quantities, creating more carbon-containing gases.
All of this evidence suggests that the extinction of life 200 million years ago was most likely caused by a violent eruption of Earth's volcanoes. And scientists have speculated that the largest extinction event on Earth, 252 million years ago, may have been caused by a violent volcanic eruption, because they found large areas of volcanic rock that formed during that period, and only supervolcano eruptions had so many eruptions. The dinosaurs really had to thank these two eruptions for helping them clear up their formidable enemies.
This is the "childhood past" of dinosaurs, full of legends and full of lucky ingredients. Unfortunately, luck always shines, in the catastrophe of the meteorite hitting the earth 65 million years ago, the dinosaurs that ruled the earth for about 150 million years failed to withstand the blow, like the two-toothed beasts and crocodile-like animals of that year, disappeared from the earth forever, leaving the throne of the earth's overlord to the rising star - mammals.
So, if the next cataclysm hits Earth, will future mammals, including humans, survive? We don't know, we can only hope that human high technology can save the lives of the earth, including human beings themselves.
Author: Boeing, Department of Geology, Class 91.
Edit: Unnamed Lake is an ocean