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Period: 4450 BCE to 4000 BCE
Hadean (Eons)
The Earth and the Solar System originated. The crust of Earth is consolidated, its primitive atmosphere is formed, reductive and anoxic, and the first seas and lakes. Large meteorites fall. High temperatures, intense volcanic activity, and the presence of conditions not favorable for life. -
Period: 4000 BCE to 2500 BCE
Archean (Eons)
End of large meteorites falling and most ancient sedimentary rocks (3900 3800). Conditions appear for the rising of primeval soup and the world of RNA. Origin of life. For the first time, abnormal amounts of carbon 13 isotopes appear, which is an exclusive component of living beings (3800). Oldest cyanobacteria fossils found inside fossilized (3650-3500). Divergence of prokaryote dominions Bacteria and Archaea from their last common ancestor. -
Period: 2500 BCE to 543 BCE
Proterozoic (Eons)
Accumulation of gaseous oxygen in the atmosphere. Large marine deposits of iron are formed. The ozone layer is formed (2500-2200). The first breathing organisms appear. An intense global glaciation takes place, called Snowball Earth (2200). First eukaryote cells appear (2150-2000). Endosymbiosis processes take place which gives rise to some eukaryote organelles. -
Period: 2500 BCE to 1600 BCE
Paleoproterozoic (Era)
Accumulation of gaseous oxygen in the atmosphere. Large marine deposits of iron are formed. The ozone layer is formed (2500-2200). The first breathing organisms appear. An intense global glaciation takes place, called Snowball Earth (2200). First eukaryote cells appear (2150-2000). Endosymbiosis processes take place which gives rise to some eukaryote organelles. -
Period: 1600 BCE to 1000 BCE
Mesoproterozoic (Era)
Diversification of eukaryote lineages. The appearance of multi cellularity in algae and their diversification. -
Period: 1000 BCE to 543 BCE
Mesoproterozoic (Era)
Separation of the lineage that gave rise to Animal and Fungi kingdoms. Most ancient fossil evidence of animals The second period of Snowball Earth takes place (750). At the end of the period, Ediacaran fauna appeared, a kind of failed evolutive experiment of rare animals. -
Period: 543 BCE to
Phanerozoic (Eons)
The explosion of the Cambric (origin and diversification of almost all lineages of modern animals). -
Period: 543 BCE to 505 BCE
Cambric (Period)
The explosion of the Cambric (origin and diversification of almost all lineages of modern animals). -
Period: 505 BCE to 435 BCE
Ordovician (Period)
Invertebrate marine animals. Trilobites and other arthropods reign the seas. -
Period: 435 BCE to 410 BCE
Silurian (Period)
Fishes appear. Invertebrates colonize landmasses. -
Period: 410 BCE to 370 BCE
Devonian (Period)
Vascular plants appear and in association with fungus in their roots, they colonize masses of land. Amphibians appear and insects diversify. -
Period: 370 BCE to 290 BCE
Carboniferous (Period)
Reptiles appear. Large swampy forests of gymnosperms and arborescent ferns cover the north of the planet. Southern masses are dry and cold. -
Period: 290 BCE to 240 BCE
Pérmico (Period)
The supercontinent Pangaea is formed. Origin of dinosaurs. At the end of the period occurs the largest massive extinction in the history of life on Earth, due to a period of world volcanism. In the seas ammonites and brachiopods. At the end of the period, mammalian reptiles originate. -
Period: 251 BCE to 65 BCE
Mesozoic (Era)
Composed by Triassic, Jurrasic, and Cretaceous periods. -
Period: 240 BCE to 205 BCE
Triassic (Period)
Large aquatic reptiles appear. Dinosaurs and their relatives, crocodiles, diversify. Turtles and sharks appear. -
Period: 205 BCE to 138 BCE
Jurassic (Period)
A period dominated by dinosaurs. Large subtropical forests of conifers, ferns, and cycads. Small mammals similar to rodents. -
Period: 138 BCE to 65 BCE
Cretaceous (Period)
Supercontinent Pangaea fragments. Rise of plants with flowers and their associations of pollination with insects. At the end of the period takes place the extinction of large dinosaurs and large reptiles and other groups, possibly by a meteorite and intense volcanism. -
Period: 65 BCE to
Cenozoic (Era)
Part of the Phanerozoic Eon, composed by the Tertiary and Quaternary Periods. -
Period: 65 BCE to 1 BCE
Tertiary (Period)
Continents reach a configuration similar to the current one. Diversification of all mammal and bird orders. In Mexico, the south and southeast regions rise from the sea, as well as Central America, connecting North America and South America. Humid forest regions diminish; new biomes such as steppes, bushes, and deserts appear. In these new conditions the lineage of large monkeys, which gives rise to the human family, appears. At the end of the period appears the mega-fauna of mammals. -
Period: 1 BCE to
Quaternary (Period)
A succession and diversification of species of the human family appear. At the end of the period, the Homo sapiens species appear and distribute throughout the whole planet as it diversifies. In Europe, it genetically integrates with the species Homo neanderthalensis. The last regional glaciation occurs. Humans domesticate plants and animals. Great civilizations appear and the current world. Are we in the process of a new extinction? -
Period: 543 to 251
Paleozoic (Era)
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Systema Naturae Rules
Linnaeus was the one who set the rules in his book Systema Naturae. He determined that species would be ordered in hierarchical or classification taxonomic categories; these categories, in decreasing direction, were: the kingdom, the class, the order, the gender, and the species. With time, two more intermediate categories were included: the family, between order and genus, and phylum, between kingdom and class. -
Modern Taxonomy
Modern taxonomy officially began in 1757 with Sistema Naturae, the classic work by Carolus Linnaeus. This module, the first in a two-part series on species taxonomy, focuses on Linnaeus' system for classifying and naming plants and animals. -
Most recent classification of Living Beings
The most recent classification, of the 19 century, adjudicated to Lamarck, was based on the presence or absence of a spinal column and cranium: vertebrates (with red blood) and invertebrates (with the blood of other colors). -
Period: to
Chemical advances
Notable advances had been made, particularly in the chemical investigation. -
Lamarck & the origin of first living beings
Lamarck appealed to explain the origin of the first living beings, basically microbes; he thought that from microbes descended, through continuous modifications, all the plant and animal species that inhabit the world. -
Louis Pasteur & spontaneous generation
Louis Pasteur felt compelled to combat spontaneous generation, in the first place, for lack of evidence, and secondly, because it was contrary to the idea that life owed its existence to natural processes. -
Evolution
Evolution is the change in the characteristics of a species over several generations and relies on the process of natural selection, and it affects physical characteristics of an organism -
Haeckel system
He created a system of three kingdoms of living beings. Protista to place there all unicellular organisms. Of these, he discovered two main types: on one in which a nucleus could be observed in their interior; he called true cells. The other was the more simple and smaller cells, nothing was appreciated in their interiors; bacteria. He called cytode to distinguish their simplicity with respect to true cells; bacteria or cytode placed in a subdivision of Protista denominated Monera. -
System of 3 Kingdoms of living beings
Haeckel created a system of three kingdoms of living beings. Protista: Place there all unicellular organisms; there are main types: those in which the nucleus could be observed in their interior: true cells, on the other side the bacteria: simple and smaller cells, in which nothing was appreciated in their interiors. These organisms he called cytode; bacteria o cytode he placed in a subdivision of Protista, denominated Monera. -
Period: to
Advances about the origin of the Universe
All the advances about the origin of the Universe, already discussed, took place. -
Oscillating or pulsating Universe
Proposed by: Alexander Friedmann
Proposes that at some moment the attraction of the force of gravity will be greater than the impulse force resulting from the explosion; therefore, the Universe will stop its expansion and will collapse back to its starting point, that is, a grand implosion or Big Crunch will occur. This will produce a pattern of explosions and implosions that will happen indefinitely or eternally. -
Oparin's proposal
In the origin of life, Oparin proposed that life on Earth had originated in a primary atmosphere, different from our present atmosphere, which is rich in oxygen. -
Edouard Chatton Classification
He observed that the presence or absence of the nucleus was the most notorious characteristic of any cell. Cells with a nucleus he called eukaryotes, which means true cells; besides, these cells have a series of organelles that perform specific and compartmentalized functions, that is, isolated from the cytoplasm. On the contrary, cells without a nucleus which he called prokaryotes, don't have organelles either so all their vital functions are carried out in their cytoplasm. -
Big Bang or great explosion
Proposed by: George Lemaitre
Proposes that the phenomenon that caused the expansion was a great explosion that took place 14,000 million years ago. Then, matter and light that exist today hadn't appeared yet. All particles that formed the atoms of the Universe have passed a process of transformation. The proofs of this theory are cosmic background radiation and the fact that the hydrogen/helium ratio that exists in the Universe is practically the same as that calculated by the model. -
Stationary State
Proposed by: Fred Hoyle, Hermann Bondi, and Thomas Gold.
Opposes the Big Bang and the Big Crunch. In its place, it proposes that the Universe is in constant expansion due to the continuous creation of new matter that fills the gaps from the center of the Universe, left by matter that was previously displaced. In this manner, it complies with the requirement of showing an apparently calm Universe; and homogeneous in the content of galaxies from all directions from which it is observed. -
World of RNA
Alexander Rich, Carl Woese, Leslie Orgel, and Francis Crick independently proposed the existence of a first biologic world based on DNA, RNA, and proteins. -
RNA molecules
Small molecules of RNA were discovered -
Inflationary State
Proposed by: Alan Guth
Is addition to the Big Bang. It explains that in the initial seconds of the explosion, matter expanded in an exponential or inflationary manner, which agrees with the homogeneity observed from any direction and also with the fact that the explosion overcame the powerful initial force of gravity when all matter was closer to the rest of matter.