The first plants and animals on earth. The first plants on Earth. The origin of life. The flowering of vascular plants after glaciation

With the reproduction of blue-green algae, also called cyanobacteria, the oxygen content in the air gradually increased. Probably, at first he destroyed a lot of bacteria, but over time they ...

With the reproduction of blue-green algae, also called cyanobacteria, the oxygen content in the air gradually increased. Probably, at first he destroyed a lot of bacteria, but over time they learned to use it in their needs. The development of different types of bacteria led to the emergence of other types of organisms that obtained energy simply by eating more primitive relatives. The next important stage began when more complex cells acquired the ability to photosynthesize due to the appearance of the chloroplast. These were the first true plant cells.

Plant evolution

The first plants were single-celled organisms that emerged when blue-green algae took refuge in large cells. These large cells already contained mitochondria, which were descended from other bacteria. In the "eyes" of cells, giving shelter to bacteria, they get a lot of advantages - mitochondria helped them use oxygen, and chloroplasts produced food for them.

These progenitors of plants, apparently, lived on the surface of the seas and lakes, as now there are numerous descendants - unicellular algae. Over time, unicellular plants developed into multicellular plants when their cells remained together after division. Some formed balls from cells, others - empty cylinders, chains of cells. Many organisms with such adaptations still live in the form of algae.

Way to land

For millions of years, algae were the only plant life on Earth. As now, they practically existed only in water, because they dried up on the ground. Then small algae began to grow on the shores of lakes, near the water. Over time, they developed semi-waterproof shells and root-like structures that sucked moisture from the soil.

These pioneering algae gave rise to mosses, primitive plants that can also survive only in damp places. Over time, more developed plants appeared, like ferns, with leaves covered with a waterproof shell. They were the first to develop roots and woody stems that allowed them to grow upward.

When did the first plants appear on Earth?

Scientists believe that the first plants on Earth appeared with the beginning of the process of photosynthesis, which took place in bacteria. This important process of interaction of liquid and sunlight has become a source of free oxygen release. Thanks to this, the plant world was born.

The first plants

Often people ask themselves which species were the first and how they appeared on our planet. Scientists gave the answer. The first representatives of the flora that managed to appear on earth were Rinia and Cuxonia. The latter looked like a small bush, the size of which did not exceed 5-7 cm. The most favorable conditions for the development of kuksonia were marshland. Traces of the presence of this Kuksonia were found in the Czech Republic, the USA and Western Siberia. Rinia is a plant similar to cuxonia. Despite the kinship of origin, the size of the rhinia was more significant - up to 50 cm in height. Initially, each of the plants had only 1 species.

According to another version, moss appeared one of the first on earth. In addition, the remains of unicellular algae and fungi were found. Swampy and shady areas are also considered to be their places of origin.

Time of appearance

There is no definite answer to the question of when plants appeared on earth. Each of the representatives of the terrestrial flora began to appear at a certain time:

• the first unicellular organisms (mosses, lichens) - 2 billion years ago;
• more complex plants (similar to modern ferns) - 4 million years;
• conifers and pine appeared about 3 million years ago;
• the age of the first flowering plants is 150 million years.

Ferns are one of the first full-fledged representatives of the flora with a root, stem and leaves. They still grow in swampy areas. By the time dinosaurs settled on the planet, its surface was already inhabited by mosses, grasses, bushes and trees. The first conifers include pine, spruce, larch and cedar. The seeds of flowering representatives, in comparison with others, had greater protection. This explains the variety of colors.

Grass and trees have evolved over time, climate change and changing conditions. Too many varieties of shrubs, flowers and trees have now been artificially bred. In order to visualize those plants that prevailed on our planet millions of years ago, you need to look at the ferns and herbs that grow in swamps and forests. They can be considered direct descendants of ancient mosses and ferns.

The first land plants and animals

WHERE LIFE BORN Life began in water. The first plants appeared here - algae. However, at some point, land appeared, which was to be populated. Cross-finned fish became pioneers among animals. And among the plants?

HOW THE FIRST PLANTS LOOKED Once upon a time, our planet was inhabited by plants that had only a stem. They were attached to the ground with special outgrowths - rhizoids. These were the first plants to land on land. Scientists call them psilophytes. This is a Latin word. Translated, it means "bare plants." The psilophytes really looked "naked." They had only branching stems with outgrowths of balls, in which spores were stored. They are very similar to the "alien plants" that are depicted in illustrations for science fiction stories. Psilophytes were the first land plants, but they lived only in swampy areas, since they did not have a root, and they could not get water and nutrients in the soil. Scientists believe that once these plants created huge carpets over the exposed surface of the planet. There were both tiny plants and very large ones, taller than human growth.

FIRST ANIMALS ON EARTH The oldest traces of animal life on Earth date back to a billion years, but the oldest fossils of the animals themselves are about 600 million years old, they belong to the Vendian period. The first animals that appeared on Earth as a result of evolution were microscopically small and soft-bodied. They lived on the seabed or in the bottom mud. Such creatures could hardly have been petrified, and the only clue to the mystery of their existence is indirect traces, such as the remains of burrows or passages. But despite their tiny size, these most ancient animals were resilient and gave rise to the first known animal on Earth - the fauna of Ediacara.

The evolution of life on Earth began from the moment the first living creature appeared - about 3.7 billion years ago - and continues to this day. The similarity between all organisms indicates the presence of a common ancestor from which all other living things descended.

ALL

psilophytes (Psilophyta), the most ancient and primitive extinct group (department) of higher plants. They were characterized by the apical arrangement of the sporangia (See Sporangium) and equal spore, the absence of roots and leaves, dichotomous or dichopodial (pseudomonopodial) branching, and a primitive anatomical structure. The conducting system is a typical Protostela. Protoxylem was located in the center of the xylem; metaxylem consisted of tracheids with annular or (more rarely) scaled enlargements. There were no supporting fabrics. R. did not yet possess the ability for secondary growth (they had only apical meristems). Sporangia are primitive, from spherical (about 1 mm in diameter) to oblong-cylindrical (up to 12 mm long), thick-walled. R.'s gametophytes are not reliably known (some authors consider horizontal rhizome-like organs, the so-called rhizomoids, to be gametophytes).

R. grew in damp and swampy places, as well as in shallow coastal waters. R.'s department includes one class - rhiniopsida (Rhyniopsida) with two orders - Rhyniales (families Cooksoniaceae, Rhyniaceae, Hedeiaceae) and Psilophytales (family Psilophytaceae). The Rhyniales order is characterized by dichotomous branching and a thin, poorly developed stele. Xylem from tracheids with annular thickenings. The oldest representative of R. is the genus Kuksonium, originally found in Wales in sediments of the late Silurian period (about 400 million years ago). The most fully studied are the Lower Devonian genera - rhinia and partly the chorneophyte, in which the rhizomoid (stems upward from it, numerous rhizoids downward) was dismembered into clearly arranged tuberous segments, devoid of conducting tissues and consisted entirely of parenchymal cells. It is believed that in the process of evolution, R.'s rhizomoids gave rise to roots. In both genera, the wall of the sporangium was multi-layered, covered with cuticles (See Cuticle). The chorneophyte is characterized by a peculiar spore-bearing cavity, which forms a dome, arched covering the central column of sterile tissue, which is a continuation of the stem phloem. In this, the horneophyte resembles the modern Sfagnum. The Rhiniaceae family also includes the genus Teniorade, many species of which formed underwater thickets in the Middle and Upper Devonian. The Lower Devonian genera of Hedei and Yaravia are sometimes distinguished into a separate family of Hedeevs. The Lower Devonian genus Sciadophyte, usually separated into a separate family of Sciadophytes, is a small plant consisting of a rosette of simple or weakly dichotomous thin stems with a stele. The order Psilophytales is characterized by dichopodial branching and a more strongly developed stele. In the most famous genus - psilophyte (from the Lower Devonian deposits in Eastern Canada) - unequally developed branches formed a false main axis of dichopodia with thinner lateral branches: the stem was surrounded by cutinized epidermis with stomata; the surface of the stem was bare or covered with spines 2–2.5 mm long, the ends of which widened discoidly, which probably indicated their secretory role. The sporangia were opened by a longitudinal crack. The Lower Devonian genera Trimerophyte and Pertica are close to psilophyte.

The study of the structure of R. and their evolutionary relationships is of great importance for the evolutionary morphology and phylogeny of higher plants. Apparently, the initial organ of the Sporophyte of higher plants was a dichotomously branching stem with apical sporangia; roots and leaves originated later than sporangium and stem. There is every reason to consider R. the original ancestral group, from which the bryophytes, lycopods, horsetails, and ferns originated. According to another point of view, bryophytes and lycopods have only a common origin with P.

Lit .: Fundamentals of paleontology. Algae, bryophytes, psilophytes, lycopods, arthropods, ferns, M., 1963; Traite de paleobotanique, t. 2, Bryophyta. Psilophyta. Lycophyta, P., 1967.

A. L. Takhtadzhyan.

Planet Earth was formed over 4.5 billion years ago. The first unicellular life forms appeared probably about 3 billion years ago. At first it was bacteria. They are classified as prokaryotes, since they do not have a cell nucleus. Eukaryotic (having nuclei in cells) organisms appeared later.

Plants are considered to be eukaryotes capable of photosynthesis. In the process of evolution, photosynthesis appeared earlier than eukaryotes. At that time, it existed in some bacteria. They were blue-green bacteria (cyanobacteria). Some of them have survived to this day.

According to the most common hypothesis of evolution, a plant cell was formed by entering a heterotrophic eukaryotic cell of a photosynthetic bacterium that was not digested. Further, the evolutionary process led to the emergence of a single-celled eukaryotic photosynthetic organism with chloroplasts (their precursors). This is how unicellular algae appeared.

The next stage in the evolution of plants was the emergence of multicellular algae. They reached a great variety and lived exclusively in the water.

The surface of the Earth has not remained unchanged. Where the earth's crust rose, dry land gradually emerged. Living organisms had to adapt to new conditions. Some ancient algae were gradually able to adapt to a terrestrial lifestyle. In the process of evolution, their structure became more complicated, tissues appeared, primarily the integumentary and conductive ones.

The first terrestrial plants are psilophytes, which appeared about 400 million years ago. They have not survived to this day.

Further evolution of plants, associated with the complication of their structure, was already on land.

During the time of the psilophytes, the climate was warm and humid. Psilophytes grew near water bodies. They had rhizoids (similar to roots), with which they were fixed in the soil and sucked in water. However, they did not have true vegetative organs (roots, stems and leaves). The flow of water and organic matter through the plant was ensured by the emerging conductive tissue.

Later, ferns and mosses evolved from psilophytes. These plants have a more complex structure, they have stems and leaves, they are better adapted to living on land. However, just like the psilophytes, they remained dependent on water. During sexual reproduction, in order for the sperm to reach the egg, they need water. Therefore, they could not "go" far from the humid habitats.

In the Carboniferous period (about 300 million years ago), when the climate was humid, ferns reached their dawn, many of their arboreal forms grew on the planet. Later, dying away, it was they who formed the deposits of coal.

When the Earth's climate began to get colder and drier, ferns began to die out en masse. But some of their species before this gave rise to the so-called seed ferns, which in fact were already gymnosperms. In subsequent plant evolution, seed ferns became extinct, giving rise to other gymnosperms before that. Later, more advanced gymnosperms appeared - conifers.

The first plants on Earth

Pollination took place with the help of the wind. Instead of spermatozoa (mobile forms), they produced sperm (immobile forms), which were delivered to the ovum by special formations of pollen grains. In addition, gymnosperms did not form spores, but seeds containing a supply of nutrients.

Further evolution of plants was marked by the appearance of angiosperms (flowering). This happened about 130 million years ago. And about 60 million years ago, they began to dominate the Earth. Compared to gymnosperms, flowering plants are better suited for life on land. We can say that they began to make more use of the possibilities of the environment. So their pollination began to occur not only with the help of the wind, but also with the help of insects. This increased the efficiency of pollination. The seeds of the angiosperms are found in the fruit, which allows them to spread more efficiently. In addition, flowering plants have a more complex tissue structure, for example, in a conductive system.

Currently, angiosperms are the most numerous group of plants in terms of the number of species.

Main article: Ferns

Riniophytes Is an extinct group of plants. Some scientists consider them to be the ancestors of mosses, ferns, horsetails and lyre. Others suggest that rhinophytes colonized the land at the same time as mosses.

The first land plants, rhinophytes, appeared about 400 million years ago. Their body consisted of green twigs. Each branch branched, dividing into two parts. The cells of the ve-points contained chlorophyll and photosynthesis took place. Material from the site http://wikiwhat.ru

Rhinophytes grew in humid places. They were attached to the soil by rhizoids - outgrowths on the surface of horizontally located vetochecks.

The first land plants

At the ends of the branches there were spore-bearing parts, in which spores matured. In rhinophytes, conductive and mechanical tissues have already begun to form. In the course of evolution, due to the occurrence of hereditary changes and natural selection on the surface of the branches of rhinophytes, an integumentary tissue with stomata that regulate water evaporation was formed.

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On this page material on topics:

• Conductive integumentary and mechanical tissues in rhinophyte and ferns

• Rhionophyta life cycle diagram

• Rhinophyta's story the answer

• Post first terrestrial plant

• When and from which group of algae did the first reniophytes appear?

Origin and taxonomy of higher plants.

Higher plants probably evolved from some kind of algae. This is evidenced by the fact that algae preceded higher plants in the geological history of the plant world. This assumption is also supported by the following facts: the similarity of the most ancient extinct group of higher plants - rhinophytes - with algae, a very similar nature of their branching; similarity in the alternation of generations of higher plants and many algae; the presence of flagella and the ability to swim independently in the male germ cells of many higher plants; similarity in the structure and function of chloroplasts.

It is assumed that higher plants most likely descended from green algae, freshwater or brackish water. They had multicellular gametangia, isomorphic alternation of generations in the development cycle.

The first terrestrial plants found in a fossil state were rhinophytes(rhinia, horney, horneophyton, sporogonites, psilophyte, etc.).

After reaching land, higher plants developed in two main directions and formed two large evolutionary branches - haploid and diploid.

The haploid branch of the evolution of higher plants is represented by the bryophyta division. In the cycle of development of mosses, the gametophyte, the sexual generation (the plant itself), predominates, and the sporophyte, the asexual generation, is reduced and is represented by a sporogon in the form of a capsule on a leg.

The second evolutionary branch of higher plants is represented by all other higher plants.

The sporophyte in terrestrial conditions turned out to be more viable and adapted to a variety of environmental conditions. This group of plants was more successful in conquering land.

Currently, higher plants number over 300,000 species. They dominate the Earth, inhabiting it from the Arctic territories to the equator, from the humid tropics to dry deserts. They form various types of vegetation - forests, meadows, swamps, fill water bodies. Many of them reach gigantic proportions.

Systematics of higher plants- this is a branch of botany that develops the natural classification of higher plants on the basis of the study and isolation of taxonomic units, establishes kinship ties between them in their historical development. The most important concepts of taxonomy are taxonomic (systematic) categories and taxa.

Plant evolution

According to the rules of botanical nomenclature, the main taxonomic categories are: species, genus, family (familia), order (ordo), class (classis), department (devisio), kingdom (regnum). If necessary, intermediate categories can also be used, for example, subspecies, genus, subfamilia, superordo, superregnum.

For species, starting from 1753 - the date of publication of the book K. Linnaeus"Plant species" - accepted binomial names consisting of two Latin words. The first designates the genus to which the given species belongs, the second - the specific epithet: for example, sticky alder - Alnus glutinosa.

For plant families, the ending is accepted - aceae, for orders - ales, for subclasses - idae, for classes - psida, for divisions - phyta. The basis of the standard unominal name is the name of some genus included in this family, order, class, etc.

Modern science about the organic world divides living organisms into two kingdoms: pre-nuclear organisms (Procariota) and nuclear organisms (Eucariota). The super-kingdom of prenuclear organisms is represented by one kingdom - the scabies (Mychota) with two sub-kingdoms: bacteria (Bacteriobionta) and cyanotea, or blue-green algae (Cyanobionta).

The super-kingdom of nuclear organisms includes three kingdoms: animals (Animalia), mushrooms (Mycetalia, Fungi, or Mycota) and plants (Vegetabilia, or Plantae).

The animal kingdom is divided into two subkingdoms: the simplest animals (Protozoa) and multicellular animals (Metazoa).

The kingdom of mushrooms is subdivided into two sub-kingdoms: the lower mushrooms (Myxobionta) and the higher mushrooms (Mycobionta).

The plant kingdom includes three subkingdoms: scarlet(Rhodobionta), real algae(Phycobionta) and higher plants(Embryobionta).

How did the first plants appear on Earth?

400 million years ago, most of the Earth's surface was occupied by seas and oceans. The first living organisms appeared in water. They looked like microscopic lumps of mucus. Several million years later, some living organisms developed a green color. They looked like algae.

Climatic conditions favored the growth and widespread dispersal of algae. Over time, the surface of the earth and the bottom of the oceans have changed. New continents rose up, those that had arisen earlier went under water. The earth's crust was shaking. This led to the fact that in the place of the seas there was land.

Retreating, sea water lingered in the depressions. The depressions sometimes dried up, then again filled with water during high tides. Algae, which used to live at the bottom of the seas, ended up on the earth's surface. However, as the desiccation proceeded slowly and gradually, during this time they managed to adapt to living in terrestrial conditions. After all, this process also took millions of years.

The climate at this time was established on the globe, humid and warm. He favored the transition of plants from an aquatic lifestyle to existence on land. These living conditions on the land have caused the complexity of the structure of plants. The structure of ancient algae changed the axis. From them the first terrestrial plants, PSYLOFITS, arose. Psilophytes resembled small herbaceous plants that grew along the banks of rivers and lakes. They had a stem that was covered with bristles. The underground part of the stem resembled a rhizome. But the very root of psilophytes, like algae, did not exist.

Mosses and ferns originated from psilophytes. And the psilophytes themselves later completely died out. It happened 300 million years ago.

The humid climate and the abundance of water contributed to the rapid reproduction of fern-like plants on the Earth - ferns, horsetails, and lyre. But at the end of the Carboniferous period, the Earth's climate began to change everywhere, becoming drier and colder. The giant tree ferns began to die. The dead plants gradually rotted and turned into coal. Later people used this coal to heat their homes.

When breeding in ferns, seeds formed on the leaves and lay open. Hence, the scientific name of HOSEED PLANTS later arose. Modern pines, spruces, and firs, which are considered gymnosperms, originated from giant ferns.

With the cooling of the climate, ancient ferns finally died out. When germinated in cold soil, their delicate shoots froze. They were replaced by seed ferns, which are considered the first gymnosperms. These plants turned out to be more adapted to life in a dry and cool climate, which was replaced by a humid and warm Carboniferous period. Their reproduction process ceased to depend on the presence of water in the external environment.

130 million years ago, grasses and shrubs appeared on Earth, in which the seeds were well protected by fruits. Therefore, they were called POSITIONAL PLANTS. Angiosperms have been dominating the earth for 60 million years.

The plant organs that were formed during these times have not changed significantly to this day.

In this article we will discuss an important and interesting topic - the emergence and development of the plant kingdom on the planet. Today, walking in the park during the lilac bloom, picking mushrooms in the autumn forest, watering home flowers on the windowsill, insisting chamomile decoction during illness, we rarely think about how the Earth looked before the appearance of plants. What was the landscape like when unicellular organisms were just emerging or the first weak terrestrial plants appeared? What did forests look like in the Paleozoic and Mesozoic? Imagine that the ancestors of those half-meter ferns, which now modestly hide in the shade of fir trees, 300 million years ago reached a height of 30 meters or more!

Let's list the main stages in the emergence of the living world.

The origin of life

1. 3, 7 billion years ago emerged the first living organisms. The time of their appearance (very approximately, with a "fork" of hundreds of millions of years) today can be assumed from the deposits formed by them. In a million plus years cyanobacteria have learned oxygen photosynthesis and so proliferated that they became the culprit of the oversaturation of the atmosphere with oxygen about 2.4 billion years ago - this led to the extinction of anaerobic organisms, for which oxygen was a poison. The living world of the Earth has changed radically!

2. 2 billionyears ago there were already different unicellular: both autotrophs and heterotrophs. These n first unicellular did not have nuclei and plastids - the so-called heterotrophic prokaryotes (bacteria). It was they who gavethe impetus for the emergence of the first unicellular plants.

3. 1, 8 billionyears ago, there were nuclear unicellular,I mean eukaryotes, soon (by geological standards)typical animal and plant cells appeared.

The emergence of multicellular plants

1. About 1, 2 billion years back on the basis of unicellular emergedmulticellular algae.

2. At that time, life existed only in warm seas and oceans, but living organisms were actively developing and progressing - they were preparing for the development of land.

Plant emergence on land

1. 4 2 0 millionyears ago, the first land plants appeared - mosses and psilophytes (rhinophytes). They appeared in many places on the planet.independently of each other, from different multicellular algae.Of course, in the beginning, they mastered only the coastal edge.

2. Psilophytes(for example, rinia) lived along the shores, in shallow water, like modern sedges. They were small, weak plants, whose life was complicated by the lack of shoots and roots.. Instead of roots with which to grip the soil properly, psilophytes had rhizoids. The upper part of the psilophyte contained a green pigment and was capable of photosynthesis. These pioneers, brave land invaders, died outbut were able to give rise to ferns.

4. Mosses - for all their unusualness, beauty and ubiquity these days, they have become a dead end branch of evolution. Having emerged hundreds of millions of years ago, they have never been able to give rise to any other groups of plants.

400 million years ago, a huge part of the earth's surface of our planet was occupied by seas and oceans. The first living organisms arose in the aquatic environment. They were particles of mucus. Several million years later, these primitive microorganisms developed a green color. In appearance, they began to resemble algae.

Plants in the Carboniferous period

Climatic conditions favorably influenced the growth and reproduction of algae. Over time, the surface of the earth and the bottom of the oceans have undergone changes. New continents arose, the old ones disappeared under water. The earth's crust was actively changing. These processes led to the fact that water appeared in place of the earth's surface.

Retreating, sea water fell into crevices, depressions. They then dried up, then again filled with water. As a result, those algae that were on the seabed gradually moved to the earth's surface. But since the process of desiccation took place very slowly, during this time they adapted to new living conditions on earth. This process has been going on for a million years.

The climate at that time was very humid and warm. He facilitated the transition of plants from marine life to terrestrial life. Evolution led to the complication of the structure of various plants, and ancient algae also changed. They gave rise to the development of new terrestrial plants - psilophytes. In appearance, they resembled small plants that were located near the shores of river lakes. They possessed a stem that was covered with fine bristles. But like algae, psilophytes did not have a root system.

Plants in a new climate

Ferns originated from psilophytes. The psilophytes themselves ceased to exist 300 million years ago.

A humid climate and a large amount of water led to the rapid spread of various plants - ferns, horsetails, and lyre. The end of the Carboniferous period was marked by a change in climate: it became drier and colder. The huge ferns began to die out. The remains of dead plants rotted and turned into coal, with which people then heated their homes.

Ferns had seeds on their leaves, which were called gymnosperms. Modern pines, spruces, and firs, which are called gymnosperms, originated from giant ferns.

With climate change, ancient ferns have disappeared. The cold climate ruined their tender sprouts. They were replaced by seed ferns, which are called the first gymnosperms. These plants have perfectly adapted to the new conditions of dry and cold climates. In this species of plants, the reproduction process did not depend on the water that is in the external environment.

130 million years ago, various shrubs and grasses arose on Earth, the seeds of which were on the surface of the fruit. They were called angiosperms. For 60 million years, angiosperms have been living on our planet. These plants have remained virtually unchanged since then.