Rock fossils (EOE)

• A fossil is the preserved remains of a dead organism from millions of years ago
• Fossils can be found in rocks and can be formed from:

  • Hard body parts, such as bones and shells
  • Parts of organisms that have not decayed because one or more of the conditions needed for decay are absent
  • Preserved traces of organisms, such as footprints, burrows, and rootlet traces
• Fossil remains have been found in rocks of all ages
• Fossils of the simplest organisms are found in the oldest rocks, and fossils of more complex organisms in the newest rocks
• Darwin's theory of evolution states that simple life forms gradually evolved into more complex ones
• By studying fossils, scientists can learn how much (or how little) organisms have changed as life developed on Earth
• There are gaps in the fossil record because many early forms of life were soft-bodied, which means that they have left few traces behind
• Fossils provide a snapshot of the past and allow us to study how much or how little organisms have changed as life developed on Earth
• Evolutionary trees are used to represent the relationships between organisms
• Branches in evolutionary trees show places where speciation has occurred, and a new species has evolved
• Information in evolutionary trees is collected from a variety of sources such as fossil records to DNA sequences