Chapter One

Paleontology

Paleontology: is the study of the history of the life on Earth as based on fossils (age, formation, & evolutionary)

Fossils: any preserved remains, impression, or trace of any living thing from a past
– are the key of understanding of past life
– give clues about organisms lived ago
– help to show that evolution has occurred
– provide evidence about how Earth’s surface was changed over time

Age of fossils: youngest from Holocene to the oldest from archaean (> 4.48Ga)
– Age of earth 4.6Ga, & the oldest fossils 3.5Ga
– most fossils are found in sedimentary rocks
– the oldest known fossils are cyanobacteria that produced structure called Stromatolites

The ancient atmosphere consists of CO, CO₂, H₂O, N₂, H₂, NH₃, CH₄, H₂S, & little free O₂

Conditions favorable for preservation

1. Rapid & permanent burial
2. Continued sediment accumulation
3. Lack of oxygen (O limits decay & scavenging)
4. Lack of heat or compression (destroy fossils)
5. Hard body parts (skeletal bones, exoskeletons)

Body fossils

actual body or body fossils that preserved may be altered (chemically or physically)

Molds & Casts

Mold & cast: 3D preservation where the original is not present

As remains buried, they surrounded with sediment

Mold impression of skeletal (or skin) remains in an adjoining rock

If buried object hollow, it infilled with sediment, the actual buried object decays or dissolved, leaving internal & external mould

Casts: are formed when an external mould is infilled by sediment or precipitated minerals
– appears as replica of original buried object
– cast is original skeletal material dissolves cavity (mold) fills with materials

The End