Final answer:
Fossil records allow scientists to construct a geologic time scale by providing evidence for relative and absolute dating of geological strata. They reveal the comparative ages of rocks and the sequential development of life forms, contributing to the understanding of Earth's history.
Step-by-step explanation:
Fossil records are vital in helping scientists construct a geologic time scale, which is a system for relating chronological dating to geological strata, known as stratigraphy. Through relative dating, geologists can determine the comparative age of different rocks and fossils, indicating which layer is older or younger within the sediment.
For instance, if rocks contain the same fossils, this suggests they were likely deposited in the same period. Another method is absolute dating which provides a more precise age. The presence of specific fossils, known as index fossils, also allows for a more accurate correlation of sedimentary layers over vast distances.
Using these methods, fossils tell the story of life's history on Earth, showcasing the evolution of species such as the horse. A fossil record can indicate the rate of speciation among early organisms, environmental conditions, and major events such as mass extinctions. The fossil record, together with other methods like molecular clocks, aids in the understanding of life's timeline, contributing to the ever-evolving geologic time scale.