FOSSILS

Vocabulary Fossil Molds and Casts Films Mineral replacement Amber Brachiopod Trilobite Dinosaur Index Fossil

Fossils Fossils are cool little pictures to our past. To be a fossil it must:

Once been aliveNow DeadBuried in sedimentNo longer of interest to bacteria.

Methods of fossilization Fossils form many ways.

Things die and then weathering, Erosion and deposition take over.

Ways to make a fossil:Molds and CastsFilmsMineral replacementAmber

Molds & Casts Organisms buried in sediment decay away

leaving a cavity or mold. If the space is filled with sediment, a cast is made.

A mold preserves a negative imprint of the surface, while a cast preserves the external form of the organism.

Films Imprints of leaves and seed cones are so

perfectly preserved that minute details are visible through modern microscopes.

Mineral Replacement

Sometimes a shell can be filled with minerals and then dissolve away.

Ground water carrying dissolved minerals infiltrates the microscopic pores and cavities in bone, wood or shell.

Amber Amber is tree sap that drips from

conifers (Pines.) This sap drips unto insects below it

trapping the insect in the sap. The sap eventually turns rock hard

and the insect remains are forever preserved in the amber.

Types of fossils you need to know.

Brachiopods – aka old clams Trilobite – looks like an old cockroach Dinosaurs – Big lizards Plants Snails – Look like today’s snails

Page 8/9 In ESRT

Index Fossils

Index FossilA fossil of an animal that lived all over the

world and didn’t live that long.

Humans (so far): Time lived________ worldwide? Yes / No

Dinosaurs: Time lived________ worldwide? Yes / No

Types of index fossils Bottom of ESRT 8/9 all good index fossils.

Tracks We can see today fossil footprints. Even in NYS there are places where Dinos

roamed.

If you look at the tracks you can

see what it was doing.

How do we use Index fossils Relative dating Correlations