Fossil evidence shows that a. mass extinctions occurred at the end of the paleozoic and mesozoic eras. b. extinctions have occurred during each period of the cenozoic era. c. extinctions occurred during each period of the paleozoic and mesozoic eras. d. all of these

The correct option is D. All of these.

Extinction is the most important process of the evolution and it has been occurring during the last 600 million years.

Each era is marked by the extinction of species due to climate change and tectonic movements.

The Paleozoic era lasted 300 million years and was divided by six periods (Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian) and it is the earliest of the three eras of the Phanerozoic eon. Each period was marked by the extinction of species, having the greatest extinction of all times at the end of the Permian era. Fossil evidence shows this era was marked by an extraordinary diversification of marine animals.

The following era was the Mesozoic era, which was divided by three periods (Triassic, Jurassic, and Cretaceous), it was also known as the Dinosaurs era. The Mesozoic era was a time of great climate change and tectonic movement and each period was also defined by great extinctions mostly because of the higher temperatures changes this era faced.  

The last era is the Cenozoic, also known as the age of mammals, it began 66 million years ago and it's extended to the present day, it is divided by three periods (Paleogene, Neogene and Quaternary).  In this periods of time there has been extinctions of different species that haven't been able to adapt to climate change.

Over 98% of all species recorded due to fossil evidence have gone extinct.

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