Science Standard 4

Utah Fossils SWBAT: understand how fossils are formed, where they may be found in Utah, and how they can be used to make inferences. Background: Fossils are evidence of living organisms from the past and are usually preserved in sedimentary rocks. A fossil may be an impression left in sediments, the preserved remains of an organism, or a trace mark showing that an organism once existed. Fossils are usually made from the hard parts of an organism because soft parts decay quickly. Fossils provide clues to Earth's history. They provide evidence that can be used to make inferences about past environments. Fossils can be compared to one another, to living organisms, and to organisms that lived long ago. Vocabulary:

o Infer: to arrive at a conclusion from evidence o Environment: surroundings o Climate: the average weather conditions for a particular place or region over

a period of years. o Dinosaur: any group of extinct often very large organisms from the Mesozoic

period. o Preserved: a maintained condition, keeping something from loss or ruin o Extinct: no longer active and existing o Extinction: the process of being extinct (no longer being active or existing) o Impression: something (as a design or footprint) made by pressing or stamping o Fossil: a trace, print, mold, cast or preserved remains of either plants or

animals o Prehistoric: before written history o Mineral: a naturally occurring solid substance o Organism: a living person, plant or animal o Replacement: process of substituting one thing for another o Trilobite: arthropod, invertebrate animal living in Paleozoic seas, composed of

three lengthwise parts divided along the back o Sedimentary: relating to rocks formed by deposit of materials by water or

wind due to weathering or erosion. o Tropical: from the area of the Earth 23° North and South of the Equator

Notes: • Fossils are evidence of living organisms from the past. • Fossils provide us with details about the lifestyle, diet, growth and movement

of a plant or animal when it was alive. • Fossil Features can be compared to living organisms that are familiar by

shape, size, pattern, and structure.

• 3 Types of Fossils Formation (Preserved, Impression & Mineral Replacement): § Preserved (soft AND hard tissues survive):

• Amber: Amber is formed when the soft resin traps an organism.

• Ice: Ice covers the whole organism preserving everything. • Tar: Sticky trap that preserves fossils.

§ Impression or tracks

• These fossils may show detailed outlines of thin plants or small animals,

• As they decay, they leave a dark print of the organism. • Impression fossils also include tracks/footprints, tail

prints, body outlines, teeth marks, and burrows. • Mold and cast are impression fossils made by larger

organisms. When the organism dies it is covered by sediment. The organism decomposes slowly and leaves a mold (hole) in its place. If the mold is later filled with sediment, it produces a cast that will physically look like the outside of the original organism.

§ Mineral Replacement of Organisms • In this type of fossil the organism is buried in sediment,

and the soft parts decay quickly. Water seeps through the sediment and passes through the bone. The seeping water dissolves the bone, and minerals replace the bone, becoming stone.

• The same process happens in wood. • The mineral replacement makes an exact replica of the

original organism.

• Utah Fossils Finds: o Trilobite fossils indicate that Millard County was an ocean o Ancient marine animal found in Cave near American Fork Canyon o Dinosaur fossils in coal indicate that Emery and Uintah County were once

tropical and swampy. o Smilodon found in Park City and mammoth in Huntington Canyon.

• Dinosaur Extinction (Scientist not sure, but these 3 are possible):

o Asteroid Theory: asteroid hit, destroyed plants, herbivores starved and carnivores left with nothing to eat.

o Volcano Eruption: eruption causes climate change, & dinosaurs didn’t adapt. o Continental Drift: land causes climate change and plants die, leaving

nothing to eat.