Millions of years ago on our planetdominated by giant dinosaurs. It is possible that they would still be here if it were not for one accident - the asteroid Chiksulub, which fell to the surface of our planet 65 million years ago. It was he, according to the results of a recent study, who caused the death of these prehistoric monsters. But who else, besides the dinosaurs, lived on Earth almost 200 million years ago? After all, after the fall of the asteroid, all dinosaurs became extinct, but life on the planet did not go away. Let's get acquainted with the amazing animals that shared the planet with giant dinosaurs.
When and how did people learn about dinosaurs?
For the first time an ancient extinct dinosaur was described by scientistsin the year 1824. Discovered nine-meter-long remains were found in early 1818 near the city of Woodstock in the UK. In 1841, the English paleontologist Richard Owen collected and summarized all the information about fossil reptiles known by that time. He called them “dinosaurs,” which in Greek means “terrible lizards.”
Shortly afterwards, in 1843 in sand slabsgeological deposits in Connecticut (USA), paleontologists have discovered traces of monstrously large birds. Compared to this find, the elephant's foot seemed miniature. Since then, researchers have been haunted by the question of how large the bird should have been, leaving these traces. The answer, as we know today, is that these tracks did not belong to the bird at all. In the Mesozoic era of the history of our planet from the Jurassic period (about 200 million years ago) to the end of the Cretaceous period (about 70 million years ago), “terrible lizards” inhabited the Earth. Some of them, like a kangaroo, ran on their hind legs, and the traces left by them strongly resemble the traces of modern birds.
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It turns out, millions of years ago, dinosaursbelonged to land, sea and air. A variety of lizards inhabited the coniferous and fern forests of the Earth. Some flew between the trees spreading their leathery wings, while others, the size of hens, ran through the glades, and huge and very slow dinosaurs - brachiosaurus - lived in the swamps. By the way, the world's largest skeleton of a brachiosaurus is in the geological and paleontological museum of the University of Berlin. The bones of this giant were discovered on Mount Tendaguru in Africa. The brachiosaurus reached a height of 11.87 m, a width of 22 m, and weighed at least 50 thousand kg. However, the biggest and most frightening, as we know today, was the tyrannosaurus rex. This predator inhabited the territory of the modern USA and Canada. In length, the monster reached 10 meters, and in height five. His meter jaws were armed with hundreds of sharp and large teeth. If a tyrannosaurus existed today, it could easily have carried a rhino in its mouth.
But if land, sky and sea were in powerdinosaurs, where, and most importantly, when mammals lived? According to a study published in the journal Science, the first mammals ran along the surface of our planet along with dinosaurs. According to the researchers, after the terrible lizards died out, all other animals came out of the shadows.
Which mammals lived with dinosaurs?
Two scientific articles tell us aboutindividual mammals that were the size of modern hamsters. The fossils of these long-extinct relatives of mammals we know were discovered in China and analyzed by an international team from the University of Chicago (USA) and the Beijing Museum of Natural History (China). After carefully examining the shape of the bones, paleontologist Jae-Si Luo from American University and his colleagues concluded that Agilodocodon and Docofossor coexisted with dinosaurs 160 million years ago.
Outwardly, these animals resembled a modern moleand squirrel. Docofossor lived underground, as evidenced by his short, wide fingers with two phalanges, similar to small shoulder blades. And the spine of this 9 centimeter mammal seems especially suitable for underground movements. In size, agilodocodon reached about 14 cm in length and lived among trees. Judging by the structure of the limbs and spine, agilodocodon was perfectly adapted to climbing trees. Researchers believe that he did not need to often go down to the ground, since he probably ate sage. Such conclusions can be made based on the structure of the animal’s teeth, which could puncture plant trunks. In addition, the researchers emphasize that in the anatomy of both animals found signs that match the action of genes found in modern mammals. Therefore, it is possible that such genetic cocktails were so evolutionarily beneficial that they have survived to the present day.
Researchers note that the discovered remainsindicate that mammals existed in the Jurassic period. It turns out that little by little we learn that other animals lived in the shadow of the dinosaurs.
But the tiny docofossor and agilodocodon were notthe only mammals that lived in the era of terrible lizards. According to the publication Sciencemag, more than 150 million years ago, the well-known Australian echidna and platypus appeared today. They represent a transitional link between reptiles and other mammals. Australian echidna is a type of egg-laying mammal, which, to put it mildly, is not quite a common occurrence. For the first time, the Australian echidna was described in 1792 by zoologist George Shaw, who several years later described the platypus. However, due to the long trunk of the animal, Shaw first decided that the Australian echidna is a relative of the anteater. Only 10 years later, anatomist Edward Home discovered a common feature in echidna and platypus - the cloaca, into which the intestines, ureters and genital tract open. Based on this feature, a single-pass detachment was further identified.
However, one of the most amazingThe discovery took place in the summer of 2000, when a team of researchers led by Timothy Row of the University of Texas at Austin accidentally stumbled upon scattered fossil bones among the rocks of the Kayent Formation in northern Arizona. At first, the found remains did not surprise paleontologists. Only 9 years later, a specialist preparing a fossil for study noticed something surprising: among the remains were tiny teeth and jaw bones only 1 centimeter long. Scientists later determined that the discovered remains belonged to Kayentaterium - an animal that lived on Earth about 185 million years ago. Adult Kayentaterium is the size of a large cat, so it could be mistaken for a mammal, if not for the large jawbone, large teeth and the absence of ears. Kayentaterium is a cynodont, a member of the group from which mammals originated.
Researchers subsequently recovered from the cliff.the remains of infants of the first mammals or their relatives from the Jurassic period, and not just one, but immediately 38. Thus, this discovery becomes one of the most significant in recent decades. Kayentaterium, according to researchers, provides important information about which traits define mammals, as well as what traits were present in their earlier relatives. The skeleton of Kayentaterium is in many ways similar to the skeleton of a mammal and at the same time to the skeleton of a reptile. The remains of the cubs suggest that, unlike mammals, which spend more time raising offspring, they were able to fend for themselves thanks to well-developed bones and teeth.
Thanks to these findings, scientists can do morelearn about the evolution of mammals. Fossil remains found in different parts of the planet disproved the belief that the mammals of the dinosaur era were small, unremarkable insectivores that lived in the shadow of giant reptiles.
Who lived on the planet after the death of dinosaurs?
The death of dinosaurs was good news formammals, the number of which increased significantly immediately after this event. So, according to the results of a study published in the journal Nature, the behavior of mammals quickly changed, as our first furry ancestors began to gradually leave their shelter not only at night, but also in the daytime. It is possible that this factor could have an impact on the evolution of Homo sapiens.
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Paleontologists and evolutionary biologists for a long timebelieved that the ancestors of modern mammals were nocturnal animals. The fact is that most mammals see well in low light. They also have developed sense of smell and hearing, and still have a mustache (such as vibrissa in cats) that allows them to feel what is right in front of them - all these qualities are incredibly useful in the dark. Similarly, when mammals began to go outside during the day, it was a mystery because behavior is difficult to distinguish from fossils. Scientists rely on the shape of the eye sockets and nasal cavities to determine which feelings were important for an extinct animal, but these clues can be misleading. However, in order to understand exactly when our ancient ancestors changed their nocturnal and diurnal lifestyles, scientists examined the daily and nightly habits of more than 2415 species of living mammals, and then used genetic data to build pedigrees, noting when the earliest daytime ancestors could have appeared on Earth.
According to the results of the study,published in the journal Nature Ecology and Evolution, the first ancestral species that was active in the daytime probably lived about 65.8 million years ago - just 200,000 years after the mass extinction that destroyed all dinosaurs except birds. For example, the common ancestor of modern camels, hippos and deer probably switched from a nocturnal to a daytime lifestyle at about the same time. Today's camels are active during the day, while hippos are active at night, and deer have a mixed lifestyle. In general, the researchers concluded that the daily activity of animals begins at the moment the dinosaurs disappeared. The reason for this, obviously, is the fact that going out during the day was too risky.
This is consistent with fossil evidence thatclearly show that the numbers and types of mammals increased rapidly after the dinosaurs died. The work supports the idea that mammals have conquered more territory and significantly expanded their behavioral repertoire. Researchers also note that modern primates are mostly active during the day, and the ancestors of primates seemed to be among the first to acquire daytime habits. This may cause us and other monkeys to have color vision and weak sense of smell, and hearing is much better than many other mammals. Thus, the fall of the asteroid Chiksulub allowed the ancient mammals to change their lifestyle and occupy the land, sea and water, which were previously owned by giant dinosaurs.