The first animals on earth. When the first animals appeared, was the Earth a ball of ice? 1 animal on earth

The first animal on Earth was Dickinsonia - a kind of soft, symmetrical cake that resembled either a feather or a palm branch.

The first animal on Earth

Dickinsonia are famous creatures. They lived approximately 560 million years ago. But were they animals? With this scientific world I couldn't decide. Some considered the “cakes” to be plants, others – mushrooms, others – lichens, and some did not “hold” Dickinsonia as independent creatures at all, but believed that they were colonies of bacteria.

Some representatives of the “mystery of nature” reached almost one and a half meters in diameter. But there were also small ones - a few millimeters each.

The remains of two Dickinsonia were recovered from a cliff located in Pomerania. The study found that the fossils preserved organic matter. Scientists have determined their composition. And they found a high concentration of cholesterol. This meant only one thing: dickinsonia were animals. After all, only representatives of the animal world produce it - cholesterol.

The current discovery of paleontologists indicates that the first animals appeared long before the so-called Cambrian explosion, which happened about 540 million years ago - living creatures then suddenly multiplied. Dickinsonia "started up" much earlier - at least 20 million years.

Dickinsonias led what is called a sedentary lifestyle. But their descendants soon moved, growing legs. And this, as it turned out, also happened many millions of years earlier than was generally believed.

The evolution of life on the planet began more than three billion years ago, some scientists say even more than four billion years. It was then that the first organized ecosystems arose, although these were microbes and bacteria, and mammals were still very far away. So what were the first animals on Earth?

The very first

The oldest traces of animal life on Earth are about a billion years old, and the oldest fossils of animals themselves are approximately 600 million years old.

The first animals that appeared on the planet were microscopically small and soft-bodied. They lived on seabed or in bottom silt. These creatures could not petrify, so the only indicator of their presence on Earth is the remains of their burrows or passages. The individuals were very resilient, and it was they who gave rise to the Ediacaran fauna - the first known animals on the planet.

Ediacaran fauna: light at the end of the Vendian tunnel

The Ediacara fauna gets its name from the Ediacara Hills, which are located in Australia. Here in 1946, unusual fossils were discovered that looked somewhat similar to modern jellyfish, worms and corals. They were small - on average 2 centimeters in diameter.

At first, scientists decided that the find dates back to the Cambrian period: it was then that the rapid development of the animal world began (approximately 570 million years ago). But with a more detailed study, it was possible to establish that these fossils are even older and belong to more ancient early period- Vendian. This was a real discovery, since no one knew for sure whether life existed during this period.

Then representatives of the Ediacaran fauna were found in different parts of the planet: in Namibia, Russia, Greenland. But despite the findings, biologists are still trying to understand what happened to them.

This is what one of these ancient animals, Kimberella, supposedly looked like:

Scientists believe that these are the direct ancestors of modern jellyfish and mollusks.

What did the Ediacarans look like?

The structure of the world's first animals was the simplest: they had no limbs, head, tail, mouth or digestive organs. The Ediacaran creatures weren't very good bright life)) at that time the planet was safe, there were no predators yet, so they didn’t even have anyone to defend themselves from.

It is assumed that they simply absorbed organic matter from the water with their entire bodies. Moreover, some of them formed a symbiosis with algae, and in appearance many of the creatures were very similar to plants.

For example, the largest creature was Dickinsonia.

Some individuals reached a meter in length, but usually did not exceed one centimeter in thickness. They had a flat, bilaterally symmetrical, grooved oval body. A kind of rug.

Scientists have not decided which group to classify it in: some consider it an ancestor of animals, some say that it is a type of mushroom, and others argue that it generally belonged to a class of creatures that do not exist today in the kingdom of nature. Yes and modern relatives she was never discovered.

What happened after the world's first animals?

The next period in the history of the development of life on Earth is called the Cambrian. It began about 570 million years ago and lasted about 70 million years. It was here that an astonishing evolutionary explosion occurred, during which representatives of most of the main groups of animals known to the world first appeared on Earth. modern science. And this happened thanks to good climatic conditions.

During the Cambrian period, huge plumes and continental shoals existed on the planet. There were ideal conditions for life here: the bottom was covered with a layer of soft silt, and warm water. A lot of oxygen has already formed in the atmosphere (although much less than now). The development of hard land covers led to the emergence of new life forms, such as arthropods - the first arthropods.

Animals needed new ways to protect themselves from new highly organized predators. As a result of evolution, creatures developed means of defense, so predators had to develop new hunting methods to overcome the resistance of the prey.

During the Cambrian period, sea levels rose and fell repeatedly, species became extinct, and were replaced by others who had to adapt to new living conditions and methods of subsistence.

The animal world became more diverse, and everything more populations could exist next to each other without claiming the food resources of their neighbors.

First mammals appeared 216 million years ago, when dinosaurs still lived and dominated the earth. According to scientists, they looked like small shrews or mice. They ate insects and plants and spent their nights in trees. Wool and others features mammals have evolved over millions of years.

The strange creature pictured below is tritylodont(Tritylodontidae), who lived in the Triassic. It was just over 1 meter long and had, as you can see, some very unusual teeth.

Its name means “three-tubercle tooth.” Behind the larger front teeth lower jaw There were teeth with two tubercles, and on the upper one - with three.

For a long time, tritylodont was alternately classified either as a mammal or as a theromorphic reptile. In terms of the structure of the teeth, with a tuberculate crown and bifurcated roots, tritylodont undoubtedly belongs to mammals, and in terms of the structure of the remaining parts of the skull it is close to theromorphs.

Scientists can only guess at its true appearance from its fossilized skull and teeth, as very few remains have been discovered.

Image of a fragment of the skull and teeth of Tritylodon longaevus (Owen, 1884)

And this triconodont(Triconodonta). Triconodont lived in the late Jurassic period and was the size of today's average domestic cat. However, it was apparently a predator and hunted a wide variety of small animals.

Some paleontologists have suggested that it could even climb trees, looking for prey or escaping from an enemy, and that it could also feed on dinosaur eggs.

Most likely they were leading night look life, hiding from predatory dinosaurs, and ate small reptiles and insects. However, as recent excavations in China have shown, some triconodonts were also capable of hunting small dinosaurs, in particular psittacosaurs.

The ecological niche previously occupied by triconodonts was occupied by the rodents that replaced them.

The remains of these animals, which had long jaws, were discovered in the territory modern Europe, where they lived in constant fear of being trampled by much larger animals.

Much like a possum, alphadon(Alphadon), lived in what is today North America. It was a marsupial, that is, it had a special pouch in which it bore its offspring. Alphadon means "chief tooth", as what was found from its remains was mostly teeth. It was probably no more than 30 cm in length.

And here Megazostrodon(Megazostrodon). He lived in the Triassic, like tritylodont. It was a small animal, similar to a shrew, growing only up to 13 cm. However, it fed mainly on insects and only came out at night, when the risk of being eaten by predators was reduced.

For the first time his fossilized remains were discovered in South Africa.

But how can scientists determine that an animal was warm-blooded from such scant remains? As a rule, the skeleton shows that the nose was separated from the oral cavity. This made it possible to eat and breathe at the same time, which most modern reptiles cannot do.

The emergence natural diversity on Earth, humanity owes billions of years of revolution. Modern geologists and paleontologists have discovered turning points in the development of life on our planet.

1. The most ancient people - Omo

People can now trace their ancestry back hundreds of thousands of years. The two skulls, named Omo 1 and Omo 2, which were discovered in Ethiopia in 1967, are 195,000 years old, making them the earliest anatomically modern humans discovered so far. Now scientists think that Homo sapiens began to develop 200,000 years ago.

However, there is still debate on this issue, since evidence of cultural development is found musical instruments, needles and jewelry - date back only 50,000 years. Complex composite tools such as harpoons also appeared around this time. Therefore, no one can answer a simple question: if modern people appeared 200,000 years ago, why did it take them a full 150,000 years to develop anything resembling a culture.

2. The most ancient bird is Protoavis

Today, everyone knows that birds evolved from dinosaurs, and also that many dinosaurs were actually covered in feathers. As a result, the question “which bird is the most ancient” essentially needs to be reformulated into “at what point can dinosaurs begin to be considered birds.”

For a long time, paleontologists considered Archeopteryx to be the most ancient birds, but today an even more ancient candidate for the title of the first bird has emerged. Protoavis lived about 220 million years ago, 80 million years earlier than any of its competitors. The fossil was found in Texas by paleontologist Sankar Chatterjee, who argues that Protoavis is actually closer to modern birds than Archeopteryx.

3. The first types of creatures that began to walk on earth - Tiktaalik and Pneumodesmus

Tiktaalik, a duck-billed creature that lived in the Devonian period, was something between a fish, a frog and an alligator. It is believed that it first emerged from the water onto land 375 million years ago. Discovered in Canada in 2004, this species is considered an important transition between aquatic vertebrates and the first land animals. Tiktaalik also boasts ribs that can support its body out of water, lungs, a movable neck and eyes on the top of its head, like a crocodile. The centipede pneumodesmus lived about 428 million years ago. The 1-centimeter-sized creature was actually the first creature to live permanently on earth and breathe air.

4. The most ancient reptile - hylonom

Reptiles were the first vertebrates that could live on earth. The lizard-like creature Hylonom, which is only 20 centimeters long, is believed to be the oldest reptile. Hylonomas, which were apparently insectivores, arose approximately 310 million years ago. Preserved fossils of this creature were discovered in 1860 inside a tree trunk in Nova Scotia.

5. The oldest creature capable of flight is Rhiniognathus

Flight as the main means of locomotion requires a complex body structure (low body weight, but a strong skeleton), as well as powerful wing muscles. The first creature that was capable of flight is actually the oldest known insect. Rhyniognatha hirsti is a tiny insect that lived about 400 million years ago. The first evidence of the existence of this insect was discovered in 1928 in Devonian rocks.

6. The first flowering plant - Potomacapnos and Amborella

People tend to associate plants with flowers, but flowers are actually relatively new. Before flowers existed, plants reproduced using spores for hundreds of millions of years. In fact, scientists do not even know why flowers arose, since they are very delicate and whimsical, and also require a huge amount of energy, which could theoretically be used much more rationally.

These incomprehensible circumstances led Darwin to describe the growth of flowers as " terrible secret". The oldest known fossil flowering plants belong to Cretaceous period, between 115 and 125 million years ago. One of the oldest flowers is Potomacapnos, which surprisingly resembles modern poppy, as well as amborella, which was found on the island New Caledonia. Everything indicates that flowers did not develop slowly, but suddenly arose in fact in their modern form.

7. The oldest mammal is Hadrocodium

The oldest known mammal resembled a small mouse or a modern shrew. The length of Hadrocodium, the remains of which were found in China in 2001, was about 3.5 centimeters, and the animal weighed only 2 grams. Most likely, it led a lifestyle similar to a modern shrew, since its teeth were specialized fangs for crushing insects. Hadrocodium lived about 195 million years, long before some of the most famous dinosaurs, including Stegosaurus, Diplodocus, and Tyrannosaurus.

8. The first tree is Wattiesa

Trees played (and still play) a crucial role in shaping the Earth's atmosphere. Without them carbon dioxide would not be converted into oxygen, and the planet would soon become lifeless. The first forests dramatically changed the Earth's ecosystem. Thus, the appearance of trees can be considered one of the most important evolutionary breakthroughs in history.

Currently, the oldest known tree is a 397-million-year-old species called Wattiesa. The leaves of this fern-like plant resembled a palm, and the tree itself reached a height of 10 meters. Wattiesa arose 140 million before the dinosaurs. The plant reproduced by spores, like modern ferns and mushrooms.

9. The oldest dinosaur is Nyasasaurus

Dinosaurs began to reign on Earth after the Permian mass extinction, which occurred about 250 million years ago and wiped out about 90 percent of all species on the planet, including 95 percent sea ​​life, and most of the planet's trees. After this, dinosaurs appeared in the Triassic.

The oldest dinosaur currently known is Nyasasaurus, whose bones were discovered in Tanzania in 1930. Until now, scientists have no the slightest idea whether he was a predator or a herbivore, and whether he walked on two legs or four. Nyasasaurus was only 1 meter tall and weighed 18-60 kg.

10. The Oldest Life Form

That is oldest form life, known science? Enough complex issue, because often the fossils are so ancient that their age is difficult to accurately determine. For example, rocks discovered near the Pilbara region of Australia contained microbes almost 3.5 billion years old. However, some scientists believe that such Precambrian organ-wall microfossils are actually a strange form of minerals that arose under special hydrothermal conditions. In other words, they are not alive.