Oldest fossils belonged to which era?

Options

A. Mesozoic era
B. Palaeozoic era
C. Precambrian era
D. Coenozoic era

Explanation

To answer the question "Oldest fossils belonged to which era?", we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Options**: The question provides four options:
- Mesozoic Era
- Paleozoic Era
- Pre-Cambrian Era
- Concoinozoic Era

2. **Understand Fossil Records**: Fossils are the preserved remains or traces of ancient organisms. The age of the fossils can help determine which era they belong to.

3. **Research the Eras**:
- **Mesozoic Era**: Known as the age of reptiles, including dinosaurs, which lived much later than the oldest fossils.
- **Paleozoic Era**: This era saw the emergence of many life forms but is still not the oldest.
- **Pre-Cambrian Era**: This is the earliest part of Earth's history, before the Cambrian period, and is known for the first simple life forms.
- **Concoinozoic Era**: This term seems to be a typographical error; the correct term is "Cenozoic Era," which is the age of mammals and also much younger than the oldest fossils.

4. **Determine the Correct Era**: The oldest fossils are found in the Pre-Cambrian Era, which dates back to about 540 million years ago. These fossils include soft-bodied organisms such as jellyfish and worms.

5. **Conclude the Answer**: Therefore, the oldest fossils belonged to the Pre-Cambrian Era.

### Final Answer:
The oldest fossils belonged to the **Pre-Cambrian Era**.

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