Fossil Types and Environments

The original minerals in a fossil are replaced with more stable minerals over time. For example, an apatite shell can transform into calcite.

The hard parts of a fossil are replaced by minerals, effectively creating a mineral replica of the original organism. This is a common way fossils are created.

Fossils that provide evidence of organism behavior, but aren't actual body parts. Examples are footprints, burrows, and fossilized droppings.

The actual, intact remains of an organism, often preserved remarkably well due to specific environments. Examples include mammoths frozen in ice.

Fossilization is most likely to occur in sedimentary rocks. This is due to the process of sedimentation, where layers of sediment build up and eventually harden into rock.

Fossils are often found in bodies of water because sedimentation occurs there. Ideal fossil locations are where the organism won't be disturbed, like a quiet part of the ocean.

These rocks form from sand and silt deposits, often found on beaches or offshore. They can preserve traces of waves, tracks, petrified wood, and hard-shelled creatures.

Coarse-grained rocks that can preserve bones, teeth, and even amphibian or reptile fossils. These rocks suggest a more energetic environment.

Fossils found in multiple locations that lived for a short geological time period, used to correlate rock layers and determine their age.

Index fossils can tell us about the environment where the organisms lived. For example, finding marine fossils suggests an ocean environment.

Sedimentary rocks are formed from the accumulation and hardening of sediments, often preserving fossils of ancient organisms.

Amber is fossilized tree resin, often preserving insects and other small organisms trapped inside.

Amber indicates that an ancient forest with resin-producing trees existed, providing exceptional preservation of delicate organisms.

Chalk is a soft, white, finely-grained rock made up of microscopic shells of marine plankton.

Chalk points to deep marine environments with abundant plankton, suggesting warm, shallow seas in the past.

Coquina is a loosely consolidated rock made of shell fragments, mainly from clams, oysters, and snails.

Coquina indicates shallow marine environments with strong currents or wave action that break down shells.

Fossil limestone primarily consists of calcium carbonate with visible fossils, indicating a marine environment.

A type of sedimentary rock known for preserving fossils, especially those of invertebrates, vertebrates, and plants.

A sedimentary rock formed from the accumulation of calcium carbonate, often containing fossils of marine organisms, especially those of vertebrates, invertebrates, and ancient fish.

A type of sedimentary rock formed from the accumulation of plant matter, often containing fossils of plants, fish, insects, and even footprints.

A sedimentary rock composed of fragmented marine shells, giving it a distinctive rough, granular texture.

A type of sedimentary rock composed of the fossilized remains of microscopic algae called diatoms, giving it a light color and soft texture.

A type of sedimentary rock composed primarily of the mineral dolomite, usually appearing in a very light pink shade.

A sedimentary rock formed from the accumulation of sand grains, typically appearing in a grainy texture and often layered, although not always.

A type of sedimentary rock composed primarily of calcium carbonate, resembling chalk in appearance and texture, and sometimes containing fossils.

Organisms that live freely in the water column, moving independently, such as fish or scallops.

Organisms that are rooted to the seafloor, unable to move freely, such as sea anemones or crinoids.

Periods of rapid warming at the end of the Pleistocene era may have made it harder for megafauna to survive by disrupting their food sources and habitats.

The introduction of humans to areas where megafauna lived may have played a role in their decline due to hunting pressure.

Changes in plant life caused by either climate change or human activities could have reduced the suitable habitats for megafauna, leading to their decline.

Fossil remains of organisms that were widespread geographically and existed for a relatively short period of time. These fossils are like time capsules, providing insights into Earth's history.

They must have been spread across a large geographic area, ensuring fossils can be found in many locations.

The species must have been abundant when it lived, increasing the chances of finding its fossils.

The fossils need to have unique features that make them easily recognizable from other fossils.

The organism must have lived during a specific, relatively short period in Earth's history, allowing for accurate dating of rock layers.

Ancient marine arthropods were common and widespread during the Paleozoic Era. Different species existed at different times, making them excellent for dating rocks.

These shelled cephalopods were widespread during the Mesozoic Era. Their fast evolution and widespread distribution make them good index fossils.

Organisms that live on the bottom of a body of water (e.g., seafloor, lakebed, riverbed).

Organisms that live within the sediment of a body of water (e.g., worms, clams).

Organisms that live on the surface of the sediment or attached to structures (e.g., starfish, barnacles).

Organisms that drift or weakly swim in the water column, unable to counteract currents (e.g., algae, diatoms, copepods, krill).

Organisms that actively swim and can move independently of currents (e.g., fish, squid, whales).