Fossils Earth Science 11

How preserved… In sedimentary rocks only, shale mostly since finer particles can preserve small details better

How preserved… Actual unchanged remains – usually only bones, but rarely, soft parts too (ex if frozen)

How preserved… Replaced remains – hard parts replaced by minerals in circulating solutions (ex petrified wood)

How preserved… Molds and Casts – shell or bone in rock, dissolved leaving mold, other material fills in space making a cast.

How preserved… Amber – hardened sap from pine trees, insects found in it (ex Jurassic Park)

How preserved… Trace fossils – tracks, burrows, poop, bite marks, etc preserved

How preserved… Carbonization – all the other elements disappear and a carbon imprint remains. (Typical of leaves)

Index fossil: Must be unique, easy to tell apart from others Found over a wide geographic area Was on Earth only a short time (in only a few rock layers) If above are true, then any time you see that fossil you know how old the rock is, no matter where the rock is.

Fossil phyla… Mollusca – clams (pelecypod), snails (gastropod), ammonoid, etc

Fossil phyla… Brachiopod – almost extinct, similar to clams

Fossil phyla… Arthropod – trilobite(extinct), spider, crab, etc.

Fossil phyla… Vertebrate – spines, people, fish, etc

Fossil phyla… Plants – live on land

Fossil phyla… Echinoderm – 5-fold symmetry, star fish, sand dollar, etc