History of the Earth — Part Two
Life Started Again, and the predators perfected their art
And life continued its incessant work, a “Work of Sisyphus”.
Bubbles begin to come out from the bottom of the seas; the methane trapped in the ices, as it melts, is released and this raises the external temperature to 40°C. (See the attachment).
And in a few tens of thousands of years again, abundant oxygen and food provide conditions for the swell of bodies and new monsters appear in the ocean, such as the Ichthyosaurs, kings of the seas.
Until the appearance of the Plyosaurus…
From the earth, small multicellular organisms survived from its depths, where they ate what they found; just like what happened to marine life, the greatest giants of all time in Earth’s history have developed: Dinosaurs.
Beginning of the Reign of the Dinosaurs
The ancestors of dinosaurs had four legs, not two; Asilisaurus kongwe, a four-legged creature the size of a large dog that is as close to the dinosaur as chimpanzees are to man, was discovered in Tanzania, eastern Africa.
A recent study concluded that the ancestor of Homo sapiens — one of the oldest in our family tree — lived in the same era as the dinosaurs, named Fruitafossor for the location where the fossil was found.
Considered the first placental mammal, it lived between 88.3 and 91.6 million years ago. Current placental mammals include humans and all other mammals except those that lay eggs or have pouches (marsupials).
“If dinosaurs hadn’t gone extinct, placental mammals wouldn’t have had a chance to diversify and our own species wouldn’t have evolved.”
There is a lot of controversies, some plausible theories, but no definitive explanation for what happened in the 33,000 years after the Permian extinction until the appearance of the dinosaurs.
There is no discernible sign of life on land, but the oceans are turning pink: fungi have proliferated in the organic matter deposits and have given rise to algae that have managed to survive.
And there were other success stories at sea, even in the midst of horror.
A large number of scientists and institutions consider the genus claraia, of bivalves, an opportunist that survived and quickly diversified to fill the spaces left in the ecosystem of the seabed by the Brachiopods, which dominated the bottom of the seas.
“To understand why the big slow giants went extinct while more fragile birds and mammals survived, we have to further explore fossil data based on molecular analysis. They suggest the intervals between Ages (see appendix) at which we can find evidence for specific groups of mammals”[2].
Thereafter, there is evidence that very diverse and different types of reptiles ruled the Earth, tens of millions of years before famous dinosaurs like Tyrannosaurus Rex, Velociraptor and Stegosaurus.
For approximately 120 million years — from the Carboniferous period to the Middle Triassic — terrestrial life was dominated by the
and the Dimetrodon
Recent studies, combining fossil analysis with DNA and specially designed programs, have shed some light on such 33,000-year-old dinosaurs as Asilisaurus kongwe. Cousin and ancestor of the dinosaurs were up to 90 cm tall, lived 10 million years before the dinosaurs,
The discovery came to demonstrate that, contrary to what was predicted, the ancestors of dinosaurs were tetrapods and herbivores and not bipeds and carnivores.
The final appearance of the great monsters took place gradually and at the same time that other smaller creatures cohabited the planet with them, such as Lystrosaurus
The final appearance of the great monsters took place gradually and at the same time that other smaller creatures cohabited the planet with them, such as Lystrosaurus,
a common synapsid, a group of ancestral mammalian animals, approximately 1 meter long and about 200 kilograms;
The announcement of the discovery of Raptorex kriegsteini bones in China, a possible miniature of the T Rex, but with a structure of only 3 meters and 70 kilos in weight,
and the story of its purchase and analysis at the University of Chicago had enormous repercussions and received fierce criticisms and opened space for deeper investigations.
The search for fossils and explanations is still alive, bringing new information such as the one about Alioramus, 5 to 6 meters in length and 800 to 2,000 kilos; a genus of tyrannosurid theropod dinosaurs from the Late Cretaceous period that lived about 70 million years ago.
An interesting video shows Tyrannosaurus Rex and the movement of its bone structure when running.
A huge meteorite crashes in what is now the Yucatan Peninsula, Mexico; explosion with energy from millions of bombs H.
The asteroid, which measured between 10 and 15 kilometers in height, crashed into the Earth 66.043 million years ago and caused a new mass extinction of life on the planet.
A cloud of debris, dust and gases covers the planet; the plants die, their predators, predators of predators.
It’s hard to believe that anything has survived.
The 165-million-year reign of the dinosaurs is over.
And its disappearance opens up an opportunity for the appearance and development of new species.
While not disregarding the theory of extinction caused by the giant meteor impact, there are a few others, of which I think the most interesting is the one that indicates that dinosaurs were doomed to extinction, even if the accident had not happened.
There are interesting articles and theses in this regard, such as the one from the BBC, click here.
The discovery of fossil fragments belonging to hadrosaurs, dating back 65 million years, that is, after the extinction, created perplexity, as this means that some dinosaurs may have survived at least 300,000 more and up to 700,000 years after the impact.
And the ship goes…
I — Birds
And, once again and as always, the void caused by the extinction of giant predators turned out to be an opportunity for other animals to appear, prey and proliferate.
Birds, descendants of theropod dinosaurs, also took advantage of the early opportunity to reconstitute our planet’s fauna. Giant, non-flying birds like Gastornis,
and the fiercest predators, the Birds of Terror
II — Mammals
A subgroup of therapsids, the cynodonts, would have evolved more mammal-like features.
In the Cretaceous (see Tables of the Earth’s Geological Ages), between 145 and 66 million years ago, flowering plants and the first placental mammals appeared.
The most primitive mammals were small and shrew-like that fed on insects. And they already had a constant body temperature. The Neocortex evolved in mammals. This brain region is typical of these animals.
The most primitive mammals were small and shrew-like that fed on insects. And they already had a constant body temperature. The Neocortex evolved in mammals. This brain region is typical of these animals.
65 million years ago the Euarchonta appeared, a group of small, nocturnal and arboreal mammals, insectivores that initiate the speciation that will result in primate orders.
Opposing Finger Development
The appearance of larger mammals begins in the Paleocene, in a tropical climate, about 65 million years ago.
And they diversified in the Eocene, 56 million years ago, into dogs, elephants, whales, bats.
Another 12 million years and the first large mammals appear during the Oligocene
5.5 million years ago the Pliocene began, when the climate became cold and dry, but with vegetation almost like today, where mammals really start to transform into types closer to humans, such as Australopithecina and the Homo Habilis.
25 million years ago Catarrhini (parvordem belonging to the suborder Haplorrhini of the Order Primates) was divided into two superfamilies,
“monkeys of the old world”
And approximately 5 million years ago, the ancestors of humans have one more influence, now from the ancestors of chimpanzees. The last common ancestor is Sahelanthropus tchadensis
The oldest in the human branch is the Orrorin tugenensis (Millennium Man, Kenya)
Both chimpanzees and humans have a larynx that repositions itself during the first two years of life to a location between the pharynx and lungs, indicating that common ancestors shared this feature, a precursor to speech.
Australopithecines evolved in the savannas of Africa,
being hunted by Dinofelis,
Body hair loss takes place over a period of 3 to 2 million years, in parallel with the development of full bipedalism.
And finally, there was Homo erectus that developed in Africa 1.8 million years ago, ancestor of modern humans, like Homo heidelbergensis, usually treated as an intermediate step towards us.
The first anatomically modern humans (Homo sapiens) evolved from Homo heidelbergensis, still in Africa, about 100,000 years ago.
From Africa they spread across the world, reaching Tierra del Fuego at the tip of South America, 10,000 years ago, taking advantage of the characteristics of the Neolithic, after the Ice Age, when temperatures began to rise.
Its characteristics, size, conformation, skin color, hair and eyes diversified, adapting to the environments, climates, facilities or adversities of the places where each group settled, and there it was divided into clans that created their domains, cities and nations .