Name the 4 types of Fossils • Mold • Trace • Casts • True form
Mold Fossils-are usually formed in sediment-organisms like shells, leaves or bones, are covered with mud-over time mud hardens-water enters mold and dissolves dead organism-mold fossils are HOLLOW on the inside
Casts fossils-need a mold fossilfirst-after organism dissolves and leaves an empty space-the empty space fills with minerals –-as time passes it hardens to form a cast fossil
Trace Fossils-are markings left by animals-examples include leaf prints, footprints, eggs and nests-Trace fossils are good for scientists to use to understand animals’ BEHAVIORS
Fossil footprints have yielded information about: Speed and length of stride whether they walked on two or four legs the bone structure of the foot stalking behavior (a carnivore hunting a herd of herbivores) the existence of dinosaur herds and stampedes how the tail is carried (few tail tracks have been found, so tails were probably held above the ground)
True Form FossilsTrue Form fossils are formed when the animals soft tissues or hard parts did not decay over the yearsbecause they are trapped in sap that hardens to become amber.This evidence gives scientists the BEST observation of past plants and animals.
Fossils start out as living things. The organism can be either a plant or an animal.
When the organism dies . . . • The soft parts that are exposed to air decompose quickly. • Hard parts like bones, shells, or wood, don’t decompose as quickly. They have the greatest chance of becoming a fossil.
The organism may be buried in layers deep in the earth. These layers might be composed of mud, lava or water. Sediments Basalt Fossil layer Sandstone Basalt Coal Sedimentary Rock Basalt
Let’s practice making inferences about living things. Would the tree live in this environment? Look at these pictures of things that come from a tree. Make a prediction about the environment where you would find this tree. … or, would the tree live in this environment? This is more difficult isn’t it? Why? What would help you decide on the correct environment?
Can you be a paleontologist? This is the environment where you are looking for fossils. Here in an example of the kinds of fossil your team has found. What do you think the environment might have been like in the past?
Let’s try another example! You just found the plant fossils, on the left, in an area where it is now hot and dry like the picture on the right. What predictions can you make about what the environment might have been like in the past?
“Once Upon a Time” is not just for fairy tales. Asian Elephant Wooly Mammoth How are these two animals the same? How are they different?
The wooly mammoth is the ancestor of the modern Asian elephant. Asian Elephant Wooly Mammoth
Once Upon a Time – A Look at the Horse Horse B Horse A
Change Over Time – A Horse’s Foot Note how the distance of the wrist bones from the ground changes. What else has changed? wrist Adapted from Florida Museum of Natural History. For more information visit their website at http://www.flmnh.ufl.edu/natsci/vertpaleo/fhc/relatives1.htm
Let’s Look More Closely How have the bones in horse feet changed over time? Why might this have happened? Adapted from Florida Museum of Natural History. For more information visit their website at http://www.flmnh.ufl.edu/natsci/vertpaleo/fhc/relatives1.htm
Wrap-Up • Fossils are formed under very special conditions. • They give us clues about what life was like long ago. • Fossils also give us clues about the environment from a long time ago. • They help us understand that plant and animal species change over time.
Rivers deposited the shells • The region was once under an ocean environment • Early Native American left them there.