Triassic Period

The great extinction that wiped out all the dinosaurs, large and small, in all parts of the world, and at the same time brought an end to various lines of reptilian evolution, was one of the outstanding events in the history of life, and in the history of the Earth.... It was an event that has defied all attempts at a satisfactory explanation.
~ Edwin H. Colbert

Indeed, despite zillions of theories that have sprung up as attempts towards explaining the sudden extinction of these prodigious saurians from the face of our planet, there has hardly been any unanimity of preference, with regards to agreeing upon any one particular theory. The Triassic Period is one such period of the evolution of Earth and its biosphere, which witnessed the emergence of the widest variety of life forms and, conversely, the biggest wave of extinction among all geologic periods.

Let's begin with when it all started. The Triassic Period was preceded by the Permian Period and succeeded by the Jurassic Period. It was the first geologic period of the Mesozoic Era and it is divided into three epochs (tens of millions of years). Each of these epochs are further subdivided into various stages, spanning over a particular period of time.

Therefore, we can say that the Triassic Period lasted between approximately 250 million years ago to 200 million years ago, and its break up into various epochs can be chronologically depicted as follows:

Rhaetian Stage
203.6 ± 1.5 till 199.6 ± 0.6

Norian Stage
216.5 ± 2.0 till 203.6 ± 1.5

Carnian Stage
228.0 ± 2.0 till 216.5 ± 2.0

Ladinian Stage
237.0 ± 2.0 till 228.0 ± 2.0

Anisian Stage
245.0 ± 1.5 till 237.0 ± 2.0

Olenekian Stage
249.7 ± 0.7 till 245.0 ± 1.5

Induan Stage
251.0 ± 0.4 till 249.7 ± 0.7

The geological composition of Earth in the Triassic Period chiefly constituted of red hued sedimentary rocks, such as sandstone and evaporites. The reason behind such geological formations was the prevailing climate, which tended a dry atmosphere.

The polar regions had a temperate and moist climate with no trace of glaciation. It is in the then rainforest like climate of the poles, that most reptiles and related creatures thrived. Cross equatorial monsoons occurred seasonally across the single, unified continental landmass.

Plant life forms belonging to the divisions lycophyta, cycadophyta, and ginkophyta, constituted the flora of this period.

Triassic Period animals included a wide variety of amphibians, crustaceans, fish, insects, mammals, mollusks, reptiles, and synapsids. Agrosaurus, Plateosaurus, Cryptoraptor, Gojirasaurus, and Eoraptor, are some of the few among a wide variety of dinosaurs from this era.

The Triassic Period was an evolutionary extravaganza and full of transitions - both progressive as well as regressive. While, on one hand a large number of species walked the Earth and swam the seas, the mass extinction during the later years wiped out much of it , making this period the cradle of oblivion for the most number of extinct animals.

The oceans and marine life forms faced this heat the most. There is considerable debate surrounding the exact reason behind such a large-scale extinction. Around the same time when these extinctions occurred, a huge volcanic eruption is believed to have taken place and many believe this to be a reason.

This eruption caused many parts to break off from the unified continental landmass, and drift away as separate landmasses. This coincided with a global cooling of the Earth and a significant bolide impact caused by a meteorite entering the Earth's atmosphere.

It is believed that these occurrences were collectively responsible for the sudden extinction of many prehistoric life forms from the Earth. Those creatures who were ill-suited to these sudden environmental developments and failed to adapt to these changes, became extinct.

That was a brief account of the events and going-ons of this prehistoric period. It's all a part and parcel of the evolutionary machinery and this thought has been very aptly put to the pen by Stephen J. Gould when he said:

If one small and odd lineage of fish had not evolved fins capable of bearing weight on land (though evolved for different reasons in lakes and seas,) terrestrial vertebrates would never have arisen.

If a large extraterrestrial object-the ultimate random bolt from the blue-had not triggered the extinction of dinosaurs 65 million years ago, mammals would still be small creatures, confined to the nooks and crannies of a dinosaur's world, and incapable of evolving the larger size and brains big enough for self-consciousness require.

If a small and tenuous population of protohumans had not survived a hundred slings and arrows of outrageous fortune (and potential extinction) on the savannas of Africa, then Homo sapiens would never have emerged to spread throughout the globe.

We are glorious accidents of an unpredictable process with no drive to complexity, not the expected results of evolutionary principles that yearn to produce a creature capable of understanding the mode of its own necessary construction.