Evidence of Change

What are fossils? What is the fossil record? How do they form? Types of fossils What do they tell us? Determining their age

Shall Sally Sell Sea Shells on the Sea Shell Shore?

Few people know the entire tongue-twister.

The author of the rhyme wants Sally to be stopped.

Sally sells seashells by the seashore. She sells seashells on the seashell shore.The seashells she sells are seashore shells, Of that I'm sure. She sells seashells by the seashore. She hopes she will sell all her seashells soon. If neither he sells seashells Nor she sells seashells, Who shall sell seashells? Shall seashells be sold?

“Sally” was really Mary Anning

1799-1847 15 months old she was hit by

lightening that killed 3 other girls Mary’s father taught her to find

“curiosities” nearby ocean cliffs Mary’s father died when she was

11. She grew up poor, and had little

education.

Mary became a great paleontologist. Her first major discovery was an Ichthyosaur She also found a Plesiosaurus and the first

Pterodactyl.

Mary Was Just One of Many. “Curiosities” were being found by

scientists all around the world. Traditionalists believed the Earth was

young (4000 – 6000 years) and the “curiosities” were the remains of recent creatures alive today.

Scientists argued the curiosities were the remains of once living creatures, and proof that the Earth was old (millions of years), and that life had changed (evolved).

Fossil = remains of past life To be a fossil the creature must be

extinct, and from the time of the last ice age or older (12,000-15,000 years old)

Fossils commonly form when the remains of a creature are quickly buried and preserved; then later exposed by erosion.

Fossils can also be preserved in amber or ice, or by tar.

Fossil Formation

The Data is in the Strata

Modern day science accepts the idea that the layers of the Earth show the past.

Different layers have different kinds of fossils.

That means life on Earth has changed (evolved).

The pattern of fossils changing can be found around the world.

The same fossils in different places mean the rocks are the same age.

Any preserved evidence of an organism Evidence can be the preserved remains of

plants or animals that lived a long time ago

Or any other preserved indications of their existence Imprints Molds & casts

Most fossils form when organisms that die become buried in sediments

Some remains that become buried in sediments actually change to rock

Minerals dissolved in the water soak into the buried remains. Gradually, the minerals replace the remains, changing them into rock. Fossils that form this way are called petrified or replacement fossils

Sometimes shells or other hard parts buried by sediments gradually dissolve and form an empty space

The hollow space in the sediment that is in the shape of the organism is called a mold

When the space becomes filled in with hardened minerals, a cast, or copy of the shape of the organism is formed

Sometimes organisms are preserved in substances other than sediments

Organisms such as the mammoth have been perfectly preserved in ice

Insects like the mosquito have been preserved in the sap of trees called amber

Trace Molds and Casts Replacement Petrified or Permineralized Amber Freezing or Mummification

http://www.toyen.uio.no/palmus/galleri/montre/x612.jpghttp://www.toyen.uio.no/palmus/galleri/montre/x612.jpg

Trace fossils are Trace fossils are indications that an indications that an organism existed, not organism existed, not the actual organism. the actual organism. They include footprints, They include footprints, nests, tooth marks, nests, tooth marks, worm burrows, root worm burrows, root traces, etc. traces, etc.

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.jpghttp://www.clas.ufl.edu/users/pciesiel/gly3603c/external.jpg

The organism is The organism is preserved but preserved but its original its original skeletal material skeletal material or pores are or pores are filled with or filled with or replaced with replaced with mineral crystalsmineral crystals

http://www.alertplumbing.com/karls_pics/122500-petrified%20wood.jpghttp://www.alertplumbing.com/karls_pics/122500-petrified%20wood.jpg

Assignment: Read pages 197 – 200 in your text, complete study guide handout and concept map on fossils(Due Friday: 10/31/2014)

http://www.youtube.com/watch?v=KxDQwBZj9o8&feature=related

http://www.youtube.com/watch?v=SEDfRy6DQns&feature=related

The Fossilization Process http://www.teachersdomain.org/resource/tdc02.sci.life.evo.becfossil/

Fossils can act like pieces in a jigsaw puzzle, helping scientists piece together information about Earth’s past.

They provide a history book of past life forms (with many missing pages)

Lets us know of extinct life forms that once lived on earth (99% of all life forms on earth are now extinct)

Shows us that there have been transitional species and evolution of species

The millions of fossils that scientists have collected are called the fossil record

Relative Dating Determine the relative age of rocks and fossils by

comparing them with other layers The Law of Superposition

Relative dating is based on the law of superposition A sedimentary rock layer is older than the layers above it

and younger than the layers below it if the layers are not disturbed

It is not a coincidence that older fossils of more primitive life forms are found at deeper and deeper layers

Index Fossils Species go extinct and others appear and sometimes they

overlap for a brief time. Index fossils = fossils or combinations that indicate a

specific time.

Match the layers, 0 is oldest, 7 is youngest.

Same fossils means the same layer. Some layers or evidence may be missing.

0

Use the fossils to put the layers in order from youngest to oldest.

A B H I JE K CL FD G