We explain what the Jurassic Period was, how it is divided and the climate it presents. Also, what are its characteristics, flora, and fauna?
On the geological timescale, the Jurassic Period is the second of the three periods into which the Mesozoic Era is divided (which began 252.2 million years ago and ended 66 million years ago). It is preceded by the Cretaceous period and followed by the Triassic.
Jurassic Period started 201 million years ago and ended 145 million years ago. Its name comes from the Jura mountain range, located between France and Switzerland, where the French geologist Alexandre Brongniart discovered the first fossils from this period and also established this geological system in the 19th century.
Dinosaurs proliferated and reigned, which is why it is perhaps the most famous of the Mesozoic periods. His name has become popular in contemporary culture thanks to books and films that explore the fictional possibility of the scientific recreation of dinosaurs (especially the Jurassic Park saga ).
The Triassic Period is the beginning of the Mesozoic era. It spanned from 251 million years ago to approximately 201 million years ago.
It begins and ends with two mass extinction events: the Permian-Triassic and the Triassic-Jurassic.
In this period the supercontinent of Pangea was formed.
The first dinosaurs appeared on earth, generally bipedal and carnivorous, as well as the first mammals (evolving from mammalian reptiles). However, at the end of the Triassic the dinosaurs diversified and began to reign on Earth.
The Jurassic Period is divided into three steps called epochs or series, which comprise eleven ages or floors. These three rungs are:
The most important geological event of the period and perhaps the entire Mesozoic era is that the fragmentation of the supercontinent of Pangea began. A slow but constant process of rifting (separation movements) occurred that divided it into two parts:
In the Jurassic, the temperature gradients were much more uniform than today, that is, the climate did not vary so much depending on the latitude. There is no evidence of polar ice, for example, which suggests that the ocean level was much higher than it is now.
Plankton floated free in the inland oceans, turning parts of the seared. Based on their presence, a whole food chain arose that, as the Jurassic passed, became larger. In this period the first frogs appear, although it was the empire of crocodiles.
The evolution of the lizards and dinosaurs of the Triassic was rapid, quickly giving rise to the largest dinosaurs, both herbivores and carnivores: Brachiosaurs, Allosaurs, Stegosaurs, Diplodocus, and others of great size and enormous weight, which in some cases required a semi-aquatic existence.
The seas were also populated by large and ferocious predators, such as ichthyosaurs, plesiosaurs, and mosasaurs, who preyed on a variety of species of cephalopods (squid-like) and ammonites. Coral reefs began their appearance in this period.
The predominant forests were coniferous, similar to the pines and araucarias of today. There were also different species of palm trees and ferns, ginkgoos, and horsetails, although there are still no inflorescences (flowers) or fruits in this period.
However, at the end of the Jurassic, the first bird in history appears Archeopteryx, whose well-preserved fossils made it possible to prove the origin of birds from dinosaurs. In these, it can be seen with its plumage, although still with many clearly reptilian features.
The oldest mammal discovered in the fossil record, a clear predecessor to what would become placental mammals, was found in 2011 in China and its existence was verified during the Jurassic. Thus it was shown that mammals evolved much earlier than traditionally thought.
Its end is determined by the so-called K / Pg Event, which is suspected to have consisted of the fall of a meteorite in the Yucatan Peninsula, causing the extinction of the dinosaurs, among many other species.
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