Download 29.1 Fossils

29.1 FOSSILS
FORMATION OF FOSSILS
What are fossils?
 Any evidence of
earlier life
preserved in rock.

Are studied by
paleontologist.
 What is
paleontology
 The study of life
in prehistoric
times.
FORMATION OF FOSSILS
What are some ways fossils can
form?
Original remains
 Replace Remains
 Molds and cast
 Trace fossils
 Carbonaceous films

FORMATION OF FOSSILS
Original Remains
What do you think they
are?
 These are the
unchanged remains of
plants and animals.
Ex. Frozen wooly
mammoth in Alaska/
Russia
 Ex. An insect trapped
in amber (hardened
tree sap)

FORMATION OF FOSSILS
Replaced Remains
What do you think
these are?
 After the soft parts
decay the
remaining hard
parts (bones, teeth,
shells…) are
replaced by rock
forming minerals.

Ex. Petrified wood
FORMATION OF FOSSILS
Molds and Cast
How are they formed?
Step 1: organism dies and is buried in sediment
Step 2: Hard parts fossilize as sediment becomes
sedimentary rock
Step 3: Fossil dissolves out of rock leaving a mold
(hollow depression in rock)
Step 4: Minerals eventually fill the opening leaving
a cast (copy of original fossil)
Ex. Shells, Ferns, Leaves, and Fish
FORMATION OF FOSSILS
Trace Fossils
What do you think
these are?
 Indirect evidence of
an organisms
existence.

Ex. Footprints,
impression in rocks,
tracks, burrows or
bite marks
FORMATION OF FOSSILS
Carbonaceous films
What do you think
these are?
 Thin film
resembling a
silhouette.

Organism
remains subject to
high temp and
pressure undergo
chemical change
leaving only a
thin film.