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Chapter 29: Studying the Past Fossils

• Paleontology: the study of the life that existed in prehistoric times

• Fossils form in several ways

– Original remains

– Replaced remains

– Molds and casts

– Trace fossils

– Carbonaceous films

• Original remains

– Full body is preserved completely

Mosquito trapped in resin (amber) Baby wooly mammoth preserved in permafrost (Siberia)

• Replaced remains

– Plants and animals parts are replaced slowly by rock-forming minerals

T-Rex… Rawr! Petrified wood… used to be plant material, now it’s all minerals

• Petrified National Forest, Arizona • Molds and casts

– Mold: A hollow depression in rock formed when a fossil dissolved out of the rock; shows the original shape and surface of the fossil

Trilobite mold and cast. It’s the Wisconsin State Fossil!

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• Molds and casts

– Cast: An object created when minerals seep into and fill a mold, forming a copy of the original fossil

Trilobite mold and cast. It’s the Wisconsin State Fossil!

• Trace Fossils

– Any indirect evidence of life preserved as an impression in rock; trails, footprints, tracks,

burrows, and bite marks

Worm trailClaw prints

• Carbonaceous film

– A thin carbon film resembling a silhouette caused by high temperature & pressure

Prehistoric wasp Ancient leaf

Photo Credits

http://www.adventurephototours.com/

http://www.creationscience.com/onlinebook/LifeSciences29.html

http://gratisbay.com/blog/2008/12/07/baby-wooly-mammoth-genome/

http://www.planet-techno-science.com/en/index.php/earth-science/first-southern-tyrannosaur-found/

http://www.legendsofamerica.com/az-petrifiedforest.html

http://www.photoatlas.com/pics02/pictures_of_usa_014.html

http://www.maine.gov/doc/nrimc/mgs/explore/fossils/bedrock/trace.htm

https://courseware.e-education.psu.edu/courses/earth105new/content/lesson02/09.html

http://www.geology.ohio-state.edu/~vonfrese/gs100/lect29/index.html

http://belmont.sd62.bc.ca/teacher/geology12/assignmentsT4.htm

http://kingfish.coastal.edu/marine/risingtide/cores/strat/intro2.html

http://www.nature.nps.gov/geology/parks/grca/age/index.cfm

http://bio-geo-terms.blogspot.com/2006_01_01_bio-geo-terms_archive.html

http://www.virginiawestern.edu/faculty/vwszaba/Phisical/chapter_6.htmsedimentary.htm