What fossils can you find in Michigan? How do fossils form? May 25, 2011 What fossils can you find in Michigan? How do fossils form?

Trace Fossil Indirect evidence left behind Footprints Burrows Animal waste

Dinosaur Ridge Morrison, Colorado http://www.dinoridge.org/

Molds and Casts Organisms buried in sediment may decay or dissolve away leaving a mold. If the space fills with sediment, an external cast can be made. Molds and casts are three dimensional and preserve the surface contours of the organism.

Replacement Original organism material is replaced by minerals Can leave replicas of hard tissue (shells, bones, etc) or soft tissue (muscle, fat, etc)

Petrified Empty spaces are filled with minerals

Amber Tree sap hardens into amber Preserves specimen

Original Material Mummified/frozen organisms

Who studies fossils? Paleontologists Reconstruction of Ichthyosaurus.

rock formed by the growth of blue-green algae or cyanobacteria stromatilite Trace fossil rock formed by the growth of blue-green algae or cyanobacteria http://www.youtube.com/watch?v=4opsN_iQdEs

ammonites Replacement/Mold and Cast 415 million years ago

Today’s organisms believed to be derived from ammonites

~225 mya Triassic period 4 x harder than granite Petrified Wood ~225 mya Triassic period 4 x harder than granite

Fossils in Michigan Are there dinosaur fossils in Michigan? There was at one time, but not now! The right age rock isn't there anymore. Glaciers came and eroded the land The rocks exposed to the ground are too old to hold dinosaurs or just junk sediment Dinosaurs lived between 235 million years to about 65 million years ago.

Fossils in Michigan: We may not have dinosaur fossils, but we do have PETOSKEY STONES! Fossils from coral reefs: Hexagonaria percarinata Devonian Period, ~ 360 million years old can be found on the shores of Lake Michigan and Lake Huron

Where have mammoths been found in the United States? Many states, but the most have been found in Nebraska About 10,000 years old

Best Preserved Fossil EVER 37,000 years ago Baby Wooly Mammoth (2007) found in Siberia Prehistoric Mammoth Discovered Quick Baby Mammoth Clip Frozen Mammoth Found Mastodon found in Rochester

Ashfall Fossil Beds Location = northeast Nebraska Hundreds of skeletons of prehistoric animals have been found in a volcanic ash bed buried beneath the rolling farmlands of northeastern Nebraska. Some of the best-preserved fossil rhinos, horses, camels, and birds Map of Land

Ashfall Fossil Beds How it happened… Volcano in southwest Idaho erupted and spread a blanket of ash over a very large area One or two feet of this powdered glass covered the flat savannah-like grasslands of northeastern Nebraska = killed animals Most of the animals survived the actual ashfall They grazed on the ash covered grasses and their lungs began to fill up with the abrasive powder. Soon their lungs became severely damaged and they began to die. The smaller animals died first (smaller lung capacities) Finally, after perhaps three to five weeks, the last of the rhinos perished. Their bodies were quickly covered by the blowing and drifting ash

KT Crater (asteroid crater) Extinction Impact High levels of Iridium (rare on earth, but common in meteorites) Thought to have caused extinction of dinosaurs

Where did life come from? First idea: spontaneous generation Disproven by Francesco Redi, Italy (1668) Used rotting meat and maggots/flies Showed flies/maggots didn’t appear in closed containers, only open ones

Where did life come from? Next Idea: Theory of Biogenesis Living organisms only come from other living organisms Louis Pasteur Nutrient broth only allowed growth after being contaminated with air

Where did life come from? First living organism Believed to arise because of primordial soup Like a big mixing bowl of atoms  molecules  macromolecules  organism Simple prokaryote like archaea Remember: no oxygen! Archaea like extreme enviros!

Where did life come from? Cyanobacteria (~3.5 bya) photosynthesizing bacteria produce oxygen thru photosynthesis! Eukaryotes (~1.8 bya) Endosymbiont theory Margulis (1966) Prokaryotes and eukaryotes had mutualistic relationship, that’s how we got mitochondria and chloroplasts!