Adaptation. A trait that allows organisms to survive and reproduce better than others without the trait in a specific environment.

Species produce more offspring than can survive. Offspring with favorable variations are more likely to survive and reproduce. Gradually, individuals with favorable variations make up more of the population.

Natural selection is a process that causes heritable traits that are helpful for survival and reproduction to become more common, and harmful traits to become more rare. This occurs because organisms with advantageous traits pass on more copies of these heritable traits to the next generation.

Evolution Acts on the Phenotype Natural selection acts on the phenotype (the traits or characteristics) of an individual. On the other hand, natural selection does not act on the underlying genotype (the genetic makeup) of an individual.

1) No empirical proof exists that macro-evolution (that is, evolution from one distinct kind of organism into another) is occurring at present, or has ever happened in the past. …

By studying the fossil record we can tell how long life has existed on Earth, and how different plants and animals are related to each other. Often we can work out how and where they lived, and use this information to find out about ancient environments. Fossils can tell us a lot about the past.

What kinds of questions can the fossil record help us to answer? Answers will vary. Some possibilities are: How did behaviors like flight evolve? What did the land look like in the past?

Paleontologists estimate that fewer than 10% of all the organisms alive today will be preserved as fossils.

Bones, teeth, shells, and other hard body parts can be fairly easily preserved as fossils. However, they might become broken, worn, or even dissolved before they are buried by sediment. The soft bodies of organisms, on the other hand, are relatively hard to preserve.

The most common process of fossilization happens when an animal is buried by sediment, such as sand or silt, shortly after it dies. Its bones are protected from rotting by layers of sediment. As its body decomposes all the fleshy parts wear away and only the hard parts, like bones, teeth, and horns, are left behind.

Desiccation, also known as Mummification, is a very unique and rare form of fossilization. Desiccated/mummified fossils are next in quality to the frozen fossils. Bones and tissues of these desiccated organisms of the desert are preserved, although they often fall apart at the slightest touch.

Whatever is being fossilized must first not be eaten or destroyed. Most bodies are consumed by other animals or they decompose. Fossils are rare because most remains are consumed or destroyed soon after death. Even if bones are buried, they then must remain buried and be replaced with minerals.

Consequently, streams, flood plains, lakes, swamps, and the ocean are good candidates for fossil-forming systems. Plant fossils are commonly preserved in fine-grained sediment such as sand, silt, or clay, or in association with organic deposits such as peat (coal).