Hello dear steemians! I am a biology teacher at school. Before beginning study the biology course, my students often ask me one question - what appeared before: plant or animal? Therefore, I decided to dedicate my first post on Steemit to this issue.
All the surrounding nature, the animal and plant world, everything living, including a man, is the result of an infinitely long evolutionary process that began after the emergence of living matter and lasted about 4 billion years. The current state of development of all living things is not permanent and final; it is only a modern stage of the modern level of that process. All organisms living at this time, ranging from the simplest and ending with person, are connected by closer or more distant relationship, the beginning of which is lost in the distant past of our Earth. They have a common origin from the primary clusters of living matter, from the primary piece of protein. The similarity between all organisms indicates the existence of a common ancestor from which all other living beings originated.
The first signs of life on Earth in the form of protein without shell in which the nucleus and protoplasm were not isolated have appeared in the so-called era of the primary oceans, when the primary oceans formed as a result of lowering the temperature and condensation of water vapor in the gorges of the earth's crust. Compared with them, even the simplest modern organisms are very complex and perfect.
The first chemical traces of life in age about 350 million years were found in the rocks of Australia (Pilbara). Later, organic carbon was discovered in rocks dating 410 million years. Perhaps, life originated in hot springs, where there were many nutrients, including nucleotides. The traces of these first manifestations of life to this day have not survived, as the rocks in which to look for these traces have undergone great changes. These first organisms can not be attributed either to the kingdom of animals or to the kingdom of plants.
Nowadays, the kingdom of plants has more than 500 thousand species, and the kingdom of animals has more than 1500 thousand species (mainly insects).
Distribution to the kingdom of plants and the kingdom of animals occurred relatively quickly, when the primary organisms as a result of moderate environmental conditions began to consume from it to maintain their existence. They consumed less and less simple organic substances and were increasingly forced themselves to create the organic substances from inorganic. Some did not succeed and they died, in others the case went well and they laid the foundation for the development of the kingdom of plants.
To date, plants are not connected in their lives with any other organic substances, unless they are parasites.
Parasitic plants are an ecological group of angiosperms, which receive the necessary nutrients from the tissues of other plants. The parasite communicates with the host plant through the haustoria that result from the transformation of the germinal root or, in rare cases, the stem tissues. To date, about 4100 species of plant parasites are known.
So, we can note that the first appeared plants. Plants are able to eat autotrophically, that is, they take from the environment inorganic substances (carbon dioxide - from the air, water with dissolved mineral salts in it - from the soil) and by means of solar energy convert these simple inorganic connections in very complex (proteins, fats, sugar, etc), from which they build their own body. This ability of autotrophic (self-feeding) is now a characteristic feature of plants, which sharply distinguishes them from animals. The food of animals is heterotrophic, that is, it depends on the substances created by living organisms.
From this perspective, the emergence of life - is the emergence of plants, because the kingdom of animals should be regarded as a lateral branch, separated from the kingdom of plants later. This view is followed by almost all modern paleontologists and biologists.
References:
http://www.sciencefocus.com/feature/environment/top-5-parasitic-plants
https://www.encyclopedia.com/plants-and-animals/botany/botany-general/evolution-plants
https://en.wikipedia.org/wiki/Timeline_of_the_evolutionary_history_of_life
