Transcript Slide 1
Fossils
What are Fossils?
Fossils are the remains of plants or animals that lived a long time ago, or any evidence of their existence.
How can Fossils be Preserved?
Unaltered Preservation Altered Preservation Molds and Casts Trace Fossils
Unaltered Preservation Insects that got stuck in tree sap were preserved unaltered. http://web.infoweb.ne.jp/minecity/park/museum/ins_03e.html
The organism is preserved but its original skeletal material is altered by chemical changes.
Altered Preservation http://www.alertplumbing.com/karls_pics/122500-petrified%20wood.jpg
Molds and Casts Molds A mold forms when something is pressed into soft mud and removed by decomposition or pulled out, leaving an impression of the object.
Casts A cast is a 3-D representation of an object from the past. It is created when a mold fills up with sediment that hardens.
http://www.clas.ufl.edu/users/pciesiel/gly3603c/external.jpg
Trace Fossils Trace fossils are indications that an organism existed, not the actual organism. They include footprints, nests, tooth marks, worm burrows, root traces, etc. http://www.toyen.uio.no/palmus/galleri/montre/x612.jpg
Where are Fossils Found?
http://necsi.org/projects/evolution/evidence/layers/layers.jpg
Why Sedimentary Rock?
http://www.arizonas-vertical-web.com/GrandCanyon/Strata.jpg
Examples of Fossils
Sporadoceras http://www.imagesco.com/catalog/fossils/
Nautilus http://www.fmarion.edu/~bio106lab/Resources/nautilus.jpg
http://www.imagesco.com/catalog/fossils/ Orthoceras
http://www.imagesco.com/catalog/fossils / Trilobites
Fossil Fish http://www.imagesco.com/catalog/fossils /
Dinosaur Bone http://www.imagesco.com/catalog/fossils/
http://www.itano.net/fossils/belden/brach1.htm
Brachiopods http://www.paxton-plts.org.uk
Echinoderms http://www.viaccess.net/~jacaroe/star.jpg
http://www.ucmp.berkeley.edu/echinodermata/sdollar.gif
Chrinoid Stems http://www.nautiloid.net/fossils/crinoids/crinoid4.jpg
http://freespace.virgin.net/craven.pendle/fossils/crinoids/stem_oss.htm
http://www.mpm.edu/reef/racine-crinoid-dior.jpg
Coral Fossils http://www.uky.edu/OtherOrgs/KPS/paleoclass/images/bentleycnidaria1.jpg
http://tolweb.org/tree/eukaryotes/animals/cnidaria/malu.jpg
Plant Fossils http://www.wayne.k12.in.us/scienceworld/rocks_&_fossils.htm
Snails and Slugs http://www.wayne.k12.in.us/scienceworld/rocks_&_fossils.htm
Now it’s time to make a fossil mold and cast!
Fossil Molds Sometimes you find a fossil mold of a shell, like this one. Depending on the shape of the mold, it is sometimes possible to make a cast of the shell
.
http://web.ukonline.co.uk/conker/fossils/casts.htm
Making a Cast By filling the mold with plaster, a cast of the fossil can be made. In nature, sediments would fill the mold and eventually harden, also forming a cast.
http://web.ukonline.co.uk/conker/fossils/casts.htm
The Cast When the plaster dries it can be separated from the mold, resulting in two types of fossils, a mold and a cast.
http://web.ukonline.co.uk/conker/fossils/casts.htm