In what era did the dinosaurs live? Today we are going to place these unique prehistoric animals in time and you will know in detail when they inhabited planet earth.

The history of the Earth can be encompassed in a great Phanerozoic Eon, which can be divided into 3 great eras:

  • Paleozoic. It begins approximately 540 million years ago and ends 250 million years ago. It begins with the great appearance of the first metazoans (complex animals) in what is known as the “Cambrian Explosion” and ends with the great Permian extinction.
  • Mesozoic. It begins approximately 250 million years ago and ends 65 million years ago. It begins after the Permian extinction and ends with the great Cretaceous extinction.
  • Cenozoic. It begins approximately 65 million years ago and continues to the present day.

When did dinosaurs inhabit the earth?

We are going to detail the different stages of the dinosaurs. These they inhabited the earth and existed for more than 160 million years during the Mesozoic Era.

The Mesozoic era can be divided into three periods: Triassic, Jurassic and Cretaceous.

  • Triassic. It begins 250 million years ago, after the end of the Paleozoic era and begins the Mesozoic era.
  • Jurassic. It begins 200 million years ago and ends 145 million years ago, being the intermediate period of the Mesozoic Era.
  • Cretaceous. It begins 145 million years ago and ends 65 million years ago, with the great extinction that ended with the “Age of the Dinosaurs”, although it was not the greatest extinction that has occurred on Earth.

Being stages so long in time, which in total add up to almost 195 million years, the great variety of dinosaurs that lived in them is very high, making dinosaurs as well known as the tyrannosaurus rex and the Stegosaurus They were separated in time by almost 90 million years.

The climatic conditions changed a lot between periods, since the Earth was (and is) never still.

In the beginning everything was a single continent: pangeabut with the continental drift, that is, with the movement of the tectonic plates, it was separating the continents first in two (Laurasia and Gondwana) and then it continued with the movement until obtaining the 5 current continents.

The tectonic plate movement explains the great variety of dinosaurs, that although they were from the same group, they could specialize in different environments and thus obtain different species, and it also allows us to explain why we find fossils of the same animal in different parts of the world since in the beginning those zones were united.

Mesozoic Era – The different periods

As we have indicated, the Mesozoic Era could be differentiated into three periods that we are going to present below:

Triassic

It is the first stage. It is the continuation of one of the greatest extinctions that has occurred on our planet, an extinction that extinguished almost 99% of the species, leaving a planet to practically remake.

That 99% of species were eliminated implies that we were on the verge of total extinction, but it also left a wide variety of niches to be colonized again.

In the Permian (last period of the Paleozoic) the most characteristic species were the reptile-mammals, animals that had more in common with the current mammals than with the dinosaurs. The loss of its hegemony meant giving way to a new group to conquer Earth, and the reptiles took over.

leshyk_permian

Mainly small animals survived, which saw a new continent to expand.

The beginning of the Triassic is characterized by a new great radiation of animals of all kinds, both reptiles and very primitive mammals (very different from today’s mammals), and the Triassic did not become an “age of dinosaurs” until its later stages.

The Triassic consists of a dry climatedue to the Pangea supercontinent, caused great differences between coastal areas, somewhat more humid and soft, and the drier and more arid interior.

Although there were “two different climates”, the existence of seasons can be confirmed (albeit extreme changes, something that occurs in temperate regions close to the tropics today). This type of climate allowed the rise of reptiles.

In the Triassic, groups began to appear that have lasted to this day (although they have changed their appearance) such as turtles (turtles) and very primitive crocodiles. It is also from this period Euparkeriaa small reptile that we have talked about in another post, but of great importance.

euparkeria-skeleton-and-silhouette

Euparkeria It was a reptile with a characteristic that made it special, a hip supported by two femurs through a joint that allowed rapid movements below its body, a tendency to bipedalism.

That he Euparkeria had this tendency was a great advance, since we can see that all dinosaurs originally had a bipedal ancestor (if we look at the forelimbs and hindlimbs, we can see that the hindlimbs are longer than the forelimbs, which indicates that developed further into ancestors).

This fleeting bipedalism of the Euparkeria It allowed a quick escape from attacks by larger animals, which evolved until it went from a fleeting bipedalism to a patent one, developing stronger hind limbs to be able to support the animal’s body all the time and not just for a few seconds.

The age of the dinosaurs has begun.

Jurassic

It is the intermediate stage, comprising about 55 million years. At this time, the largest dinosaurs appear, such as the family of the Diplodocusand carnivores like Allosaurus. It is the “age of the giants”.

The beginning of the Jurassic is due to the separation of the supercontinent Pangea in twoone to the north and one to the south, separated by the Tethis Sea, which are Laurasia and Gondwana.

The fact that it separated into two continents allowed the Jurassic period to have more regular climates, similar in a large number of areas, since the coastal areas increased and the internal continental ones decreased, so we went from an arid and dry climate to a more humid and warm, with rains and milder temporary changes.

laurasia-gondwana

This more humid climate allows the rise of the great forestsand with it the appearance of the first angiosperms, the first flowering plants. It supposes the beginning of a displacement of the gymnosperms, plants without flowers that appeared in the Carboniferous (Paleozoic stage).

Although the first basal angiosperms appeared, the rise of large forests was of gymnosperm plants and ferns among the most important.

This hot and humid climate It allowed the dinosaurs to acquire great sizes, they had no limits, dense forests that did not end and the competition between them was predator-prey.

At the same time that the dinosaurs begin to increase in size, they must leave behind the characteristic poikilothermia (cold blood) and look for other habits in order to keep a body of that size active as soon as the sun rises, so many dinosaurs began to develop feathers.

archeopteryx2

Feathers are epidermal structures initially responsible for regulating body temperature efficiently, allowing them to live in both hot and cold environments (although with their respective specializations). That they have subsequently allowed the flight is “collateral damage”.

The oldest feathers of which there is evidence and evidence are filamentous proto-feathers (similar to chicken down) dating from the Jurassic, 155 million years ago, belonging to a specimen of the theropod Anchiornis huxleyia dinosaur before the famous archeopteryx.

The feathers were a structure originated to combat environmental changes and thus survive the seasons.

Cretaceous

The Cretaceous began 145 million years ago, although its beginning is due more to a series of biotic factors than to the separation of continents, as occurred in the two previous periods.

The water levels were the highest, almost all the land was submerged.

There was a great radiation of species within the angiosperm plants, beginning to displace the gymnosperms more; there was a great boom in the radiation of species and also in the dinosaurs, which began to differentiate into true birds.

Fig-6-Reconstruction-of-the-Late-Cretaceous-ecosystem-in-which-the-hadrosaur-dinosaur

At the end of the Cretaceous, before the great extinction occurred, the horizons of today’s continents were already beginning to be observed. Today’s North America and Eurasia would separate from Laurasia, while South America, Africa, Oceania, Antarctica and India would separate from Gondwana.

When the separation of the continents began, although it was still a very slight separation, large internal water masses were formed. Global climate change did not start until the end of the Cretaceous, with the great extinction. There are several hypotheses about it, but here I present the one that is currently believed to have happened.

Actually it was not a single factor that caused the extinction on a large scale of the dinosaurs, but a set of factors that together wiped out much of life on earth.

An increased release of methane from the Earth’s inner layers caused overheating similar to what is currently occurring with climate change, but in greater amounts.

It caused an atmosphere that favored extreme environments and changes. Later, a meteorite of several kilometers arrived that is supposed to have fallen in the current Yucatan Peninsula.

The friction of the meteorite with the atmosphere full of methane caused the sky to literally burn, the fall encouraged an increase in tectonic activity, which from the negative point caused earthquakes but from the positive point favored the separation of the aforementioned continents.

After the great amount of fire and destruction, came a drastic climatic change: a extremely cold weather due to large dust cloud that rose after every point on Earth had burned, starting a “nuclear winter” (these events are the same assumptions behind a possible large-scale nuclear war).

The large dust cloud covered the entire Earth for years, greatly lowering the planet’s temperature.

End of the age of dinosaurs: a new beginning

Without sunlight, the survival of any species was practically zero…unless a few small nocturnal animals survive, and adapted to total darkness they could advance and fight to live. There were herbivores and carnivores, all small.

But, How to live without the oxygen that plants give? Well, there are two important points: not only do plants give oxygen, there are also a series of microorganisms like the Cyanobacteria that provide that oxygen to the environment, and their predecessors were the ones that allowed the entire planet to be oxygenated even before the first fish appeared.

In addition, many plant species have seeds that can enter a dormant stage until conditions are favorable again, and can last for decades and centuries in that state.

Life after the great extinction of the Cretaceous was hard for all active living beings, but thanks to that hardness, survival capacity and the strength to live, they were able to return to Earth the life it had.

If you want more information about all the periods of the history of the earth and the animals that inhabited it in general, we invite you to read: The Ages of the Dinosaurs and the Beginning of Life.