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How do we know life has changed? Fossils — the preserved remains of ancient plants and animals — are nature’s own record, layer by layer.
- Fossils are preserved remains of plants and animals found in layers of rock, sand and mud.
- Generally, older layers hold simpler organisms , while newer layers show more complex forms.
- From giant dinosaurs to early humans and ancient plants, fossils act as natural records of how life has changed over millions of years.
Birbal Sahni was an eminent scientist who studied fossil plants. He founded the Birbal Sahni Institute of Palaeosciences (BSIP) in Lucknow, which continues his work on ancient plants and past environments. His studies linked present-day plants with their ancestors and showed that life on the Earth has a long, connected history.
Why do classification systems keep changing? Because science evolves as we learn more. Aristotle’s system worked for his time, but new tools like microscopes and staining techniques revealed microorganisms, so the classification changed. Biological classification — and science — is an ongoing process of reasoning and change.
