Final answer:
The geological record shows that there have been at least five mass extinction events in the past 570 million years, marked by significant biodiversity loss. These major events are identified as occurring at specific times in Earth's history, with one of the most significant being the asteroid impact that led to the extinction of the dinosaurs.
Step-by-step explanation:
The geological record indicates there have been at least five mass extinction events in the past 570 million years. These events are evident due to the sudden and dramatic losses in biodiversity, where more than half of all extant species disappeared from the fossil record.
The mass extinctions identified by paleontologists occurred around 450 million years ago, 360 million years ago, 250 million years ago, 205 million years ago, and about 65 million years ago, which is notable for the extinction of most dinosaur species except birds. While there are many extinction events recorded in the history of Earth, these five mass extinctions are the most renowned because they represent the most extreme decreases in biodiversity.
One of the most recognized causes of these extinction events, particularly the one around 65 million years ago, is believed to be the impact of a large asteroid in the present-day Yucatán Peninsula, leading to significant climatic shifts caused by ejected atmospheric dust. The Phanerozoic eon, which started about 542 million years ago, encapsulates all these major extinction events, shaping the evolutionary trajectory of life on Earth.