Animals May Have Evolved Much Earlier Than We Thought

Topic: Earth Science

Scientists have found evidence that animals may have existed hundreds of millions of years before they first appear in fossil records. A study led by the University of Oxford suggests that animals could have originated deep in the Neoproterozoic Era, possibly before some of the most severe ice ages in Earth's history.

Scientists have long believed that animals evolved around 539 to 487 million years ago during the Cambrian Period. However, new research suggests that this may not be true. A team of researchers led by the University of Oxford found evidence that animals may have existed hundreds of millions of years before they first appear in fossil records.

The study focused on a site called the Weng'an Biota in China, which is around 590 million years old. This site contains microscopic organisms preserved in exceptional detail, but none can be definitively identified as animals. Because of this absence, scientists have previously argued that animals likely evolved after the Weng'an Biota formed.

However, the new research calls this assumption into question. The team examined microfossils from a site called the Kheseen Biota in Mongolia, which is more than 40 million years younger than Weng'an. Despite being well-preserved, none of the fossils can confidently be identified as an animal.

The researchers argue that the absence of animals from Weng'an cannot automatically be taken as proof that animals had not yet evolved 590 million years ago. Instead, they examined much older fossil deposits dating from about 850 to 730 million years ago. These included the Svanbergfjellet Formation in Norway, Bitter Springs Group in Australia, and Chuar Group in Arizona, USA.

The study's findings suggest that animals may have occupied environments different from those represented in the Kheseen deposits, or that the chemical conditions responsible for fossilization there were not suitable for preserving animal remains.

Why It Matters

This discovery can help us better understand how life on Earth evolved and how it has changed over time. It also highlights the importance of continued research into the history of our planet and its inhabitants.

Key Facts

• The study suggests that animals may have existed hundreds of millions of years before they first appear in fossil records.
• The Weng'an Biota site in China is around 590 million years old, but none of the microscopic organisms preserved there can be definitively identified as animals.
• The Kheseen Biota site in Mongolia is more than 40 million years younger than Weng'an and has well-preserved microfossils, but no animal fossils can be confidently identified.
• The researchers examined fossil deposits dating from about 850 to 730 million years ago, including the Svanbergfjellet Formation in Norway and Bitter Springs Group in Australia.
• The study's findings suggest that animals may have occupied environments different from those represented in the Kheseen deposits.

Key Terms

Neoproterozoic Era

A time period in Earth's history, around 1 billion to 541 million years ago.

Implications

This discovery can help us better understand how life on Earth evolved and how it has changed over time. It also highlights the importance of continued research into the history of our planet and its inhabitants.