fossils
TRANSCRIPT
Fossils and Evolution
So, what is a fossil anyway?
• On your paper, write a definition for the term fossil.• What do you think they are?• What are they made of?• Where are they found?• What types of things can be fossils?
Let’s recap…• Fossils (from Latin fossus, literally "having been dug up")
• Fossils are the preserved remains or traces of animals,
plants, and other organisms from the distant past.
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http://www.treasure-hunting-team.com/a27-treasure-hunting-for-fossil-fish.php
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http://www.geosociety.org/graphics/gv/PikesPeak/03fossilWasp.htm
Let’s recap… There are several types of fossils:
• Body fossils - made from actual organic material from a creature or plant (like a bone).
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http://www.norway.org/ARCHIVE/restech/ida/
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http://science.nationalgeographic.com/staticfiles/NGS/Shared/StaticFiles/Science/Images/Content/triassic-plant-446443-ga.jpg
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http://ruskosplanet.blogspot.com/2009_07_01_archive.html
Let’s recap… There are several types of fossils:
• Trace fossils - A trail, track, or burrow made by an animal and found in ancient sediments such as sandstone, shale, or limestone.
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http://www.envs.emory.edu/faculty/MARTIN/ichnology/Arthrophycus.htm
Burrows from a worm-likeAnimal.
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http://www.envs.emory.edu/faculty/MARTIN/ichnology/tf-coprolites.htm
It’s what it looks like… fossilized poop!
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http://www.citizendia.org/Trace_fossil
Tracks from a Chirotherium
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http://dinosauriosdeargentina.blogspot.com/2009/02/dinosaurios-de-la-rioja.html
Let’s recap… There are several types of fossils:
• Mold fossils - form when the material surrounding the organism hardens followed by removal of the organic matter. This leaves behind an impression (or mold) of the organism.
• Cast fossils - form when a mold fossil is filled with some form of mineral.
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http://petrifiedwoodmuseum.org/moldscasts.htm
A mold fossil of anammonite.
A cast fossil of anammonite.
Fossil Record
• The total number of fossils that have been discovered, as well as the information gained from them.
• In a nutshell, here’s what we know from the fossils that have been discovered…
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Single-Celled Organisms1 Billion years ago
Simple multi-cellular organisms500 Million years ago
Fish without jaw bones400 million years ago
Fish with jaws350 Million years ago
Amphibians250 Millions years ago
Reptiles200 Million years ago
Birds150 Million years ago
Mammals100 Million years ago
Our current era!
Can you believe that fossils of single-celled organisms have been found? It sounds crazy, but it’s true!
How do we know how old they are?!
Relative dating• Using relative dating, scientists can look
at where the fossils are in the earth to determine how old they are. They look at the sediments above and below a fossil; this allows scientists to say that an organism lived after one species (found in the rock below it), and before another species (found in the rock above it).
How do we know how old they are?!
Absolute Dating
• Scientists also use absolute dating, sometimes it’s called “Carbon 14” dating or just “Carbon dating”. Carbon 14 decays at a constant rate, so scientists can measure the amount of radioactive carbon still in the sample and figure out how old it is.
The interactive Tree of Life!An interactive fossil record!
How do fossils support evolution?