What does this fossil record tell us?
Fossils are remains or other evidence of organisms that lived in the past and are preserved in the rocks. https://teachingscience.us/the-fossil...
Common fossils include complex parts like bones, teeth, and eggs of animals, wood, leaves, and other parts of plants, shells, corals, and tiny shells of microfossils. Exceptionally, soft tissue of plants and animals may be found fossilized in permafrost (like Ice Age mammoths preserved in the Siberian tundra), insects and seeds preserved in amber (resin from trees), bodies of animals preserved by mummification, plant material preserved in peat, and other rare occurrences of fossilized soft tissue. Some fossils consist of impressions of body parts, for example, the mark of the skin of dinosaurs left on the preserved footprints, images of plant leaves and insects, etc. Some ancient molecules (DNA, protein, keratin, collagen, etc.) have been preserved in bones, shells, and other fossils.
Another type of fossil is trace fossils, or ichnofossils, in which no body parts are preserved but evidence of the organism's activity before it died. Common ichnofossils are burrows made in the sediment before it became indurated, footprints of vertebrates and invertebrates walking on soft ground, borings in shells and rocks, coprolites (fossil excrements), and root traces.
The many different kinds of fossils occurring in sedimentary layers form what is called the fossil record. The fossil record is incomplete and biased. That means many organisms are rarely or never represented as fossils. Some microorganisms are much scarcer as fossils than when they were alive. Most animals that live today are insects or other land invertebrates, but they are scarce in the fossil record. The fossil record is biased because animals with hard shells and skeletons are represented better than soft-bodied animals or plants (jellyfish, insects, algae, etc.). It is also biased in that land animals are poorly represented. Despite these limitations, paleontologists agree that the fossil record is adequate to study the past.