Bio 4 lsn2

Fossils

remains/imprints of animals that have been preserved in sediments that turned into rock

Types of fossils

Mold, cast, trace, true form

Mold fossil

Animal leaves imprint behind

Cast fossil

Imprint/mold filled with minerals that turn into rock; bone gets replaced by rock

Trace fossil

Not full body; footprints, nests, eggs

True form fossil

In amber, ice, etc.; whole body preserved

Ways of fossil formation

Gradual replacement of minerals, casts + impressions, preservation

Gradual replacement of minerals

Bones, teeth, etc. decay slow and are replaced by minerals, form rock-like substance and can be seperated for a perfect model

Casts + impressions

Organism buried in soft material (clay), as clay hardens organism decays, left with gap. impression = footprint

Preservation

No decay: animal stuck in amber/tor pit, there’s no oxygen or moisture so decay can’t happen, animal remains intact

How can animals go extinct?

Environment changes, new predator, disease, new species outcompetes, catastrophic events, hunters

Amber

Fossilized tree resin that often preserves ancient insects or organic matter inside

Tar pits

Natural pools of asphalt or tar that trap and preserve the bones and remains of prehistoric animals

Sedimentary rock

Rock formed over time by the accumulation and compression of mineral and organic particles, where fossils are typically found.