Question

What major biological events occurred near the end of Proterozoic time?

Short answer

Near the end of the Proterozoic time, major biological events included the development of multicellular life, the appearance of the Ediacaran biota, a significant rise in oxygen levels in the atmosphere due to the Great Oxygenation Event, and the occurrence of Snowball Earth events. These events collectively contributed to the evolution of complex life forms and laid the groundwork for the emergence of plants and animals.

Step-by-step solution

Understanding the Proterozoic Time

The Proterozoic time, also known as the Proterozoic Eon, is a geological eon representing the period from about 2.5 billion years ago to 541 million years ago. This time encompasses the development of life before the appearance of most animals. The Proterozoic was characterized by significant changes in Earth's atmosphere, climate, and life forms.

Identifying the End of the Proterozoic Time

The end of the Proterozoic time is marked by a transitional period known as the Ediacaran Period, which took place from around 635 million years ago to 541 million years ago. This period marked important changes in the development of life on Earth.

Major Biological Event 1: Development of Multicellular Life

One of the major biological events near the end of the Proterozoic time was the development of multicellular life. Prior to this time, life on Earth consisted predominantly of single-celled organisms such as bacteria and archaea. The emergence of multicellular life allowed for the growth of larger and more complex organisms, which ultimately led to the development of plants and animals.

Major Biological Event 2: The Ediacaran Biota

Another major biological event from this time period is the appearance of the Ediacaran biota. The Ediacaran biota is a term used to describe a group of soft-bodied organisms that lived during the Ediacaran Period. The fossils found from this period serve as some of the earliest evidence of complex multicellular life forms on Earth. These organisms ranged in size and shape, displaying a wide variety of unique body plans.

Major Biological Event 3: The Rise of Oxygen in the Atmosphere

A pivotal biological event that occurred during the end of the Proterozoic time was the significant rise in oxygen levels in the Earth's atmosphere. This event, known as the Great Oxygenation Event or the Oxygen Revolution, marked a crucial change in the environment, which allowed for the development of more advanced life forms that rely on oxygen for their survival. The rise in oxygen levels is attributed to the photosynthetic processes of cyanobacteria, which gradually produced enough oxygen to alter the composition of the atmosphere.

Major Biological Event 4: The Snowball Earth

Near the end of the Proterozoic time, there were global glaciations, known as Snowball Earth events, which covered most of the planet in ice. These events had a significant impact on the climate, as well as the development and diversification of life. The melting of the ice caps contributed to the increase in ocean nutrients, eventually leading to the evolution of complex marine organisms. In conclusion, the end of the Proterozoic time was marked by several significant biological events, including the development of multicellular life, the appearance of the Ediacaran biota, a rise in oxygen levels in the atmosphere, and the Snowball Earth events. These events contributed to the development of complex life forms and the eventual emergence of plants and animals.