The action of natural selection consists in selecting individuals more adapted to a given ecological condition, eliminating those disadvantaged for that same condition. The most appropriate expression refers to the greater likelihood of a given individual surviving and leaving offspring in a given environment. Natural selection acts permanently on all populations. Even in stable and constant environments, natural selection acts in a stabilizing manner, is present, eliminating deviant phenotypes.
An adaptation is a feature that is common in a population because it provides some improved function. Adaptations are very fit for their functions and are produced by natural selection. Adaptations can take many forms: behavior that allows better predator avoidance, a protein that works best at body temperature, or an anatomical feature that allows the body to access valuable new resources - all of which can be adaptations. Many of the things that most impress us in nature are believed to be adaptations.
The first four-legged animals to reach land were classified as tetrapods the term tetra means four. So tetrapods refer to animals with four limbs.
Pangaea also known as Pangea was a supercontinent during the late Paleozoic and Mesozoic times. It incorporated almost the earth's land masses. The formation and breaking up of continents is a geological cyclic process. And there seemed to have many supercontinents that existed before Pangaea. And according to the sources it assembled from the earlier continental parts approximately 335 million of years ago.
Glaciation is a geographical term that explains the formation, movement, and recession of the glaciers and this process was much more evident in times when the world was covered with ice sheets. Glaciers are nothing but in simple words huge chunks of ice which gets accumulated over a period of time, whose movement is governed by its own weight. Due to this ice layers are built which keep on growing slowly together forming a thick mass of ice.
Waterbody never stops moving and this tidal movement brings a lot of changes in the environment around- flora and fauna. However, global warming causing the melting of ice and glaciers has impacted heavily on this causing the extinction of certain species.
Earlier when these environmental changes were not so rapid, marine life in terms of flora and fauna flourished underwater. There was no soil erosion, seawater contamination in terms of industrial waste being released and other contaminants causing loss of marine life.
