One of the scales of geological time that make up the Precambrian is the ProterozoicThis is an Eon that began approximately 2500 billion years ago and lasted until 542 million years ago. During this period, major, momentous changes took place on planet Earth, including the appearance of the first photosynthetic organisms and the increase in oxygen in the atmosphere. In other words, during this Eon, our planet became habitable.
In this article we are going to tell you all about the characteristics, geology, climate, flora and fauna of the .
Key features
Among the main characteristics that predominate in the Proterozoic we find the presence of cratons on our planet. These cratons are nothing more than nuclei where the continents were located. That is, cratons were the first structures from which continental shelves could be created and formed. These cratons are made up of archaic rocks. The antiquity these rocks range from 570 million years to 3.5 giga years.
The main characteristic that cratons have is that they do not suffer any type of formation fracture over the years. These are the most stable areas of the entire earth's crust. We can also see that during the Proterozoic stromatolites appeared. They are structures formed by microorganisms and precipitated calcium carbonate. These stromatolites have been studied by scientists for a long time and it has been discovered that they not only have cyanobacteria but there are also organisms such as fungi, insects, red algae, etc.
These stromatolites form geological records of great importance for the study of life on the planet. Another characteristic that made the Proterozoic notable is the increase in oxygen concentration in the atmosphere. Thanks to this increase in oxygen in the atmosphere, a great deal of biological activity was possible, which we can better understand if we consider the Archean organismsAtmospheric oxygen did not reach a significant level but helped to enhance the diversification of organisms.
There was a great event or one of great importance and significance that includes a series of events related to this increase in atmospheric oxygen. And it is that the amount of oxygen exceeded the maximum amount that the chemical reactions were capable of absorbing. Anaerobic organisms were directly affected and their populations began to decline. These organisms were called methanogens, since their main food source was methane. This disappearance of methane had climatic consequences that led to a significant drop in global temperatures.
Proterozoic Geology
Little is known about this Eon, but it is known that the primary changes were at the level of plate tectonics. At that time, our planet rotated much faster on its axis than it does today. This meant that a day on Earth lasted only 20 hours. In contrast, the translational movement had a slower speed than today. Thus, a full year was 450 days.
Great information has been obtained from rocks from the Proterozoic. These rocks have been deformed by the effect of erosion, although others could be rescued without hardly being altered.
Flora and fauna of the Proterozoic
During this period, the first organic life forms began to develop further after their appearance during the 19th century. It was thanks to the transformation that occurred in the atmosphere that living beings were able to diversify and spread throughout the land. Ecosystems themselves began to form, and flora and fauna specific to each ecosystem began to develop. This is due to genetic adaptation, which occurs when an animal or plant has to adapt to different environmental conditions.
Prokaryotic organisms began to develop during the Archaic, but they developed further during the Proterozoic. Among these prokaryotic organisms we find the green algae known as cyanobacteria and the general bacteria themselves.
During the passage of time of this Eon we can see that the first eukaryotic organisms appeared that already have a defined nucleus. The first green algae of the class of Chlorophytas and red algae belonging to the class of Rodhophytas were the first to appear. Both classes of algae are multicellular and photosynthetic. By carrying out photosynthesis, they contributed to the expulsion of oxygen into the atmosphere.
It is important to note that all living things that inhabited during the Proterozoic Eon they did it in aquatic environments. And it is in the ocean that the minimum conditions necessary for survival were found. In this sense, it is interesting to better understand the Ediacara fauna.
Regarding the fauna, we can say that during this period of time some organisms that today are considered little evolved were found, such as sponges. It has been possible to recover fossils of animals that belong to a wide group in which they are jellyfish, corals, polyps and anemones. The main characteristic of these groups of animals is that they have radial symmetry.
You've probably heard of the . This is about the discovery of fossil sites that represented the earliest known living beings on this planet. Fossils of sponges and anemones were observed, as well as other species that still baffle paleontologists.
Climate
At the beginning of the Proterozoic, the climate was fairly stable. The atmosphere contained a large amount of greenhouse gases, most notably methane. However, with the development of cyanobacteria and the production of photosynthetic organisms, a massive release of oxygen into the atmosphere occurred. This led to a reduction in atmospheric methane due to the death of anaerobic organisms. As the amount of greenhouse gases in the atmosphere decreased, less solar radiation was retained, and global temperatures decreased.
During the Proterozoic there were several glaciations. The most devastating was the Huronian ice age. This glaciation occurred 2.000 million years ago and resulted in the disappearance of the anaerobic living beings that existed at that time.
The Proterozoic Aeon is mainly divided into 3 eras: It was Paleoproterozoic, it was Mesoproterozoic, and it was Neoproterozoic.
I hope that with this information you can learn more about the Proterozoic.