Question

In which era did the Ediacaran fauna live? A) Precambrian C) Mesozoic B) Paleozoic D) Cenozoic

Short answer

A) Precambrian

Step-by-step solution

Understanding the Terms

The exercise asks about the era in which the Ediacaran fauna lived. To begin, it's important to understand what is meant by "Ediacaran fauna." The Ediacaran fauna refers to the earliest known complex multicellular organisms. These organisms are dated back to a specific time frame in Earth's history.

Identifying Geological Eras

We need to identify within which geological era the Ediacaran period falls. The major geological eras are the Precambrian, Paleozoic, Mesozoic, and Cenozoic. The Precambrian is the earliest part of Earth's history, spanning from the formation of Earth about 4.6 billion years ago up until 541 million years ago.

Locating the Ediacaran Period

The Ediacaran period is a subdivision of the late Precambrian. It occurred approximately between 635 and 541 million years ago, just before the Cambrian explosion. This positions the Ediacaran fauna firmly within the Precambrian era.

Answer the Question

Given that the Ediacaran fauna is dated within the Ediacaran period, which belongs to the Precambrian era, the answer to the question of during which era the Ediacaran fauna lived is "Precambrian."

Key concepts

Geological Eras

Earth's history is a profound narrative divided into large segments known as geological eras. These eras help us understand the immense timescale over which different natural events have occurred, leading to the planet's current form. There are four major geological eras that scientists recognize:

• Precambrian: The earliest and longest era, from Earth's formation around 4.6 billion years ago to about 541 million years ago. It encompasses significant events such as the formation of the Earth’s crust and the appearance of the first known life forms.
• Paleozoic: Following the Precambrian, spanning from 541 to 252 million years ago. It's known for the Cambrian explosion that resulted in a significant increase in the biodiversity of life forms.
• Mesozoic: Lasting from 252 to 66 million years ago, famously known as the "Age of Reptiles", when dinosaurs roamed the Earth.
• Cenozoic: The current era, starting 66 million years ago, continuing to today, and showcasing the domination of mammals and birds.

Each era is further divided into periods, epochs, and ages, which help geologists pinpoint specific events and developments in Earth's geological and biological history.

Precambrian Era

The Precambrian era is a fascinating chapter in Earth's history, beginning with Earth's formation around 4.6 billion years ago, and ending approximately 541 million years ago. Although it spans almost 88% of Earth's history, this era is often less detailed and underemphasized compared to later eras due to the fewer preserved fossils available from this time.

• Absence of Hard-shelled Organisms: It is known for the dominance of simple, single-celled organisms such as bacteria and algae, and later, the introduction of multicellular organisms.
• First Complex Life: The end of the Precambrian, known as the Ediacaran period, showcases the appearance of the first complex life forms that laid the groundwork for future biodiversity in the Cambrian explosion.
• Tectonic and Atmospheric Changes: Significant developments occurred, such as significant geological changes, the formation of supercontinents, and the dramatic increase of oxygen in Earth's atmosphere (Great Oxygenation Event).

The Precambrian is crucial in Earth's history as it set the stage for subsequent biological evolution and geological formations.

Multicellular Organisms

Multicellular organisms are life forms made up of more than one cell, marking a critical evolution step allowing more complex structures and functions. The transition from single-celled to multicellular life is considered one of the biggest evolutionary leaps in the history of life on Earth.

• Early Evolution: The first known multicellular organisms date back to the Ediacaran period, at the end of the Precambrian era. These were simple, soft-bodied organisms like sponges and jellyfish.
• Advantages: Being multicellular allowed organisms to become larger, differentiate their cells, and perform specialized functions, increasing survival and adaptability.
• Diversity and Complexity: Following their appearance, there was rapid diversification and an increase in the complexity of life forms, leading to the historical biological event known as the Cambrian explosion.

The development of multicellular organisms paved the way for the diversity of species we observe today, making it a cornerstone topic in understanding life's evolution on our planet.