The Fossil Record

Triceratops was a plant-eating dinosaur that stood about 9 to 10 feet tall. Scientists reconstructed its shape, size, and behavior by studying fossils, which are preserved remains or traces like footprints, bones, and teeth.

Most organisms do not become fossils after death because decomposers like bacteria and fungi, along with scavengers such as flies and beetles, quickly break down tissues. Soft tissues, including muscles, feathers, and fur, usually decay. Harder parts like bones, teeth, and shells are more likely to be preserved.

In rare cases, organisms are preserved almost intact, such as a mammoth frozen in ice or a spider trapped in amber. But most fossils are found in sedimentary rocks and often appear as fragments rather than complete bodies.

Sedimentary fossils form when sand or mud quickly covers an organism or its tracks, protecting them from decay and scavengers. Over time, pressure compacts the sediment into rock, forming layers called strata that record life from different time periods.

Stratigraphy, the study of rock layers, helps scientists estimate the relative ages of fossils. As newer layers form above older ones, fossils found higher in the strata are generally you