What best defines the fossil record?

• A. Group of fossils analyzed and arranged chronologically
• B. History of life documented by fossils preserved in sedimentary rock
• C. Fossils preserved only in volcanic rocks
• D. A catalog of meteorite fossils

Answer: (B)

The fossil record is the history of life documented by fossils preserved in sedimentary rock. Sedimentary rocks form in layers as particles settle and burial protects remains from decay, so over long timescales these layers accumulate and preserve fossils that can be read like a timeline of past organisms. This layering also allows scientists to compare fossils from different locations and link them to relative ages of the rocks.

The other ideas aren’t as accurate because simply grouping fossils chronologically describes how we study the record, not what the record itself is. Fossils in volcanic rocks are not the primary source for most of life’s history—volcanic processes can destroy or alter fossils and don’t typically preserve long, continuous histories. A catalog of meteorite fossils doesn’t reflect life on Earth at all; meteorites pertain to space rocks, not Earth’s biological history.