Download The Fossil Record 8-3

The Fossil Record
8-3
8-3
The Fossil Record

Fossils – Traces or remains
of plants or animals

Found in sedimentary
rocks
Interpreting the Fossil Record

Clues to environmental
changes

Marine fossils found in desert
areas
Fossilization

Most animals
decompose or are
eaten after death.

Usually just hard parts of
organisms become
fossils
Mummification

Removal of internal organs

Wrapping the body in cloth

Dry areas

Not much bacteria
Amber

Hardened tree sap

Insects become trapped and
preserved

DNA - rare
Tar Seeps

Petroleum oozes to the
surface

Animals become
trapped
Freezing

Organisms buried in frozen
ice or soils do not decay

Bacteria cannot survive
Petrification

Mineral solutions replace
original organic sediment
with new material
Imprints

Carbonized imprints

Partially decays and leaves
print behind
Molds and Casts

Shells leave empty cavities or
molds

Sand or mud fills in holes and
form casts
Coprolites

Fossilized poop

Feeding habits
Gastroliths

Stones in dinosaurs digestive
system
Types of Fossils

Trace fossils – fossilized
evidence of organisms

Footprints
Index Fossils

Used to determine relative age of
rocks

Fossils widespread, abundant, and
distinct

Lived during a short time span
Index fossils – Absolute Age

Rock and fossil can be
assumed to be close to
the same age