Monday January 7, 2013 (Types of Fossils)

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Assignment Currently Open Summative or Formative? Date IssuedDate Due Date Into GradeSpeed Final Day Quiz 14S412/12 12/191/16

Recent Events in Science Billions and Billions of Planets! Read All About It! ler/news/kepler html Look up at the night sky and you'll see stars, sure. But the sky is also filled with planets -- billions and billions of them. That's the conclusion of a new study by astronomers at the California Institute of Technology in Pasadena, which provides yet more evidence that planetary systems are the cosmic norm. The team made their estimate while analyzing planets orbiting a star called Kepler planets that are representative, they say, of the vast majority of planets in our galaxy and thus serve as a perfect case study for understanding how most of these worlds form. "There are at least 100 billion planets in the galaxy, just our galaxy," says John Johnson, assistant professor of planetary astronomy at Caltech and coauthor of the study, which was recently accepted for publication in the Astrophysical Journal. "That's mind-boggling.“ "It's a staggering number, if you think about it," adds Jonathan Swift, a postdoctoral student at Caltech and lead author of the paper. "Basically, there's one of these planets per star."

Fossils

Fossils - Evidence of Past Life Fossils, the remains or traces of prehistoric life, are important inclusions in sediment and sedimentary rocks. The study of fossils is called “paleontology.”

Fossils - Evidence of Past Life Fossils are the remains or traces of prehistoric life. Types of Fossils The remains of relatively recent organisms may not have been altered at all. Examples include bones, teeth, and shells.

Fossils - Evidence of Past Life Far less common are entire animals that have been fossilized because of unusual circumstances. These have been only slightly modified, and are referred to as “mummified fossils.”.

Fossils - Evidence of Past Life Modified Fossils Petrified fossils have had the small cavities and pores of the original structure filled with precipitated mineral matter.

Fossils - Evidence of Past Life Modified Fossils Replacement fossils have had the cell material removed and replaced with mineral matter.

Fossils - Evidence of Past Life Modified Fossils Mold and cast fossils - when a shell or other structure is buried in sediment and then dissolved by underground water, a mold is created. The mold reflects only the shape and surface markings of the organism; it does not reveal any information concerning its internal structure. If the hollow spaces are then filled with mineral matter, casts are created.

Fossils - Evidence of Past Life Modified Fossils Carbonization fossils are created when fine sediment encases the remains of an organism. As time passes, pressure squeezes out the liquid and gaseous components and leaves behind a thin residue of carbon.

Fossils - Evidence of Past Life Modified Fossils Impression fossils are replicas of the fossil’s surface preserved in fine-grained sediment.

Fossils - Evidence of Past Life Modified Fossils Amber-preservation fossils are hardened resin (sap) of ancient trees surrounding an organism.

Quick Quiz The study of fossils is called _______________. Which of the following fossils would yield the greatest amount of information about the ancient organism? paleontology __________ are the remains or traces of prehistoric life. Fossils