Paleontological essays, short essays on paleontology

The mammoth was a large mammal that lived in the Cold Era, very similar to the elephant of today, except that its tusks were long and curved upwards, and its head was high.

Mammoths lived in the Quaternary Great Ice Age in the Northern Hemisphere, 3 million years ago 10,000 years ago, generally 5 meters tall, weighed about 10 tons, and lived on grass and shrub leaves. Because of its long hair, it can withstand severe cold, and has always lived in the grasslands and hills of the alpine zone.

Mammoths suddenly became extinct when they lived 10,000 years ago, what caused it? Experts have done careful research and found many causes, but they are still caused by both external and internal factors. External Factors:

As the climate warms, mammoths are forced to move northward, their areas of activity are shrinking, and the grassland plants are decreasing, leaving mammoths without enough food and facing the threat of starvation; Internal causes: slow growth rate. In the case of modern elephants, which take 22 months from conception to farrowing, mammoths live in cold regions and are speculated to have a longer pregnancy period.

Under the pursuit of humans and beasts, the survival rate of young elephants is extremely low, and the number of ** killed is closer to modern times, once the balance between their reproduction and death is disrupted, their numbers will inevitably decrease rapidly until extinct.

It is a diverse group of dominant vertebrates of the Mesozoic era, dominating the world's terrestrial ecosystems for more than 160 million years. Dinosaurs first appeared in the Triassic period 230 million years ago and died out in the late Cretaceous period, about 65 million years ago, during the late Cretaceous period. In 2005, Japanese archaeologist Kansuzu discovered new evidence that dinosaurs may have hatched in eggs.

The Archaeopteryx fossil found in 1862 is very similar to the Eugenesaurus fossil, except that the Archaeopteryx fossil has traces of feathers, suggesting that the dinosaur may be a close relative of the bird. Since the 1970s, many studies have pointed to the probability of modern birds as direct descendants of theropod dinosaurs. Most scientists consider birds to be the only dinosaurs that have survived to this day, while a few even believe that they should be classified in the same class.

Crocodiles are modern relatives of another group of dinosaurs, but they are more closely related to dinosaurs than birds. Dinosaurs, birds, and crocodiles all belong to the archosaur clade of reptiles, which first appeared in the Late Permian and became the dominant fauna in the Middle Triassic.

In the first half of the 20th century, both scientists and the general public regarded dinosaurs as slow-moving, lazy, cold-blooded animals. But the Dinosaur Renaissance, which began in the 1970s, suggested that dinosaurs may have been active warm-blooded animals and may have behaved socially. Numerous recently discovered evidence of the relationship between dinosaurs and birds supports the hypothesis that dinosaurs were warm-blooded.

Trilobite is the most representative ancient animal, which appeared in the Cambrian period hundreds of millions of years ago, developed to its peak 500 million years ago, and was completely extinct in the Permian period 100 million years ago, and survived on the earth for more than 100 million years before and after, which shows that this is a kind of organism with strong vitality. Over time, they have evolved into a wide variety of species, some up to 70 centimeters long and some as small as 2 millimeters. The dorsal shell is divided into three parts longitudinally, hence the name trilobite.

The ancestors of trilobites may have been arthropod-like animals, such as the Sprig worm or other trilobite-like animals from the Ediacaran period of the cryptozoic epoch. Early trilobites share many similarities with Burgess Shale and other Cambrian arthropod fossils, so trilobites may have shared a common ancestor with other arthropods before the Ediacaran and Cambrian borders.

Trilobites developed rapidly, reaching their reproductive highs in the late Cambrian era. In order to adapt to different living environments, the morphological evolution is diverse. Some heads, thorax and tails are equal in size, the shell is flat, and the head and tail lack obvious decorations, such as big-headed insects).

Some of the heads are broad and large, and the anterior edge is surrounded by a flat perimeter, on which there are also neat nodules, such as cryptotritumrum; In order to avoid damage, some are decorated with long needle punctures on the chest and tail, such as schizoles (some shells can also be curled into balls, such as cryptocephalic insects.

The exact cause of trilobite extinction is unknown, but the presence of sharks and other early fish with strong palates and jointed joints during the Silurian and Devonian periods appears to be related to the decline in the number of trilobites that appeared at the same time. Trilobites may provide an abundant food for these new animals.

In addition, by the late Permian, the number and variety of trilobites were quite small, which undoubtedly provided the conditions for their extinction during the Permian-Triassic extinction event. The previous Ordovician-Silurian extinction event, although not as severe as the later Permian-Triassic extinction event, had greatly reduced the diversity of trilobites.

Pterodactyl originally meant a flying reptile. The pterosaur that appeared on Earth during the Triassic period of the Mesozoic Era was the first vertebrate capable of flight, but there are suspicions that it was only in name only, and at best it could glide through the sky. However, the latest research has shown that because of the well-developed neural tissue in the brain that processes balance information, pterosaurs were not only able to fly like birds, but also to be expert at flying.

Although it's not original, it's still okay, and I've modified it, so it should be okay.

Dinosaurs were reptiles that appeared 245 million years ago and flourished 65 million years ago. Or a vague general term for dinosaurs and their contemporaries, plesiosaurs, pterosaurs, etc. The sudden disappearance of dinosaurs at one point has become a mystery in the history of the evolution of life on Earth, a mystery that no one has solved to this day.

All of the earth's past creatures are recorded in fossils. In the strata of the Mesozoic era, many dinosaur fossils have been found. A large number of bones can be seen in a variety of shapes.

However, in the Cenozoic strata that followed, there were no dinosaur fossils at all. It is inferred that the dinosaurs became extinct together during the Mesozoic Era.

There are many types of dinosaurs, and their body shape and habits are also very different. The largest of them can be as large as dozens of elephants combined; It's small, but it's about the same as a chicken. In terms of diet, dinosaurs had tame vegetarians and ferocious meat eaters, as well as omnivorous dinosaurs that ate both meat and vegetables.