GSCI 1050 Lecture 13: 02.28.2017

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GSCI 1050
Jennifer Cooper Boemmels

GSCI1050-002 02.28.2017 Midterm Exam THURSDAY -Be here on time (if not early) -Bring device as exam is through HuskyCT -You MUST have your ID to receive credit for the exam Sessions 1-13 are important, covered on exam, includes today 50% is multiple choice (about 50 questions), 50% is essay. 1/3 of multiple choice questions will come directly from prep quizzes. How to view old prep quizzes? Got to prep quizzes and “view graded feedback on HuskyCT” - click on MyGrades, click on title of the quiz ou want to see, then click on the score you got which will take you to the quiz. Should be the same for in-class quizzes. Essay - would bring in a variety of different topics. Best way to prepare for that is to study material with learning materials as your structure. You do need to focus on the textbook because it has more info that we couldn’t go over. You don’t have to memorize nitty gritty of the text; she mentioned what was important on the study guide don’t need to memorize order of periods, only hierarchy of larger divisions, don’t need to memorize geologic time scale Clicker Q Which of the following principles is most important for sedimentary rock correlation across great distances? a) fossil succession b) cross-cutting relationships (if something is older, it will be cut by younger features) c) original horizontality (sediment is deposited horizontally because of gravity) d) uniformitarianism (present is key to the past) b, c and d are just rock features. however, they really have to rely on fossil record to correlate across great distances. Fossils -Taphonomy -Time and Space -Mass Extinction -Biodiversity and Paleogeography Taphonomy • Paleontology, the study of fossils, is a complex subject.
 • Dichotomies:
 ◦ Body vs. Trace ▪ body fossil - the remains of an organism (ex: bone, shell fragment) ▪ trace fossil - some marker that has been left by a living organism (ex: footprint, burrow, evidence of feeding) ◦ Macro vs. Micro ▪ macro fossils (ex: dinosaur) ▪ micro fossils are those we look at through a microscope ◦ Chemical vs. Physical ▪ chemical fossils are just some sort of chemical signature left in rock record that serves as an indicator of life (ex: carbon isotopes) ◦ Index vs. Background ▪ index fossils - fossils of organisms that existed in particular environments that lived for relatively short period of geologic time, making it easy to narrow down its geologic time span, and has distinct features associated with it, making it easy to identify ▪ background fossils - fossils that change through geologic time, but are no useful for correlation across great distances • Fossils are formed in sedimentary rock • There are many ways to become a fossil. But it’s not easy to become a fossil. ◦ Trace Fossils (you need a material that can make that impression from the living organism like mud, and then it has to be buried somehow) ▪ Footprints etc. ▪ Burrows ▪ Feeding Marks ▪ Nests ▪ Chemicals ◦ Body Fossils (you can have an organism frozen in permafrost that is exposed to us when it melts, but it doesn’t take us too far back in geologic time; or one that is dried in a desert; or a bug trapped in tree sap/amber; or petroleum seeping up that gets degraded and becomes viscous tar that traps an organism) ▪ Frozen ▪ Dried ▪ Tar & Amber ▪ Hard parts (flesh doesn’t remain) ▪ Molds & casts ▪ Xeroxes (carbonized) ▪ Permineralized (minerals get deposited in the cavities of the bones) ▪ Petrified (wood that has undergone burial and mineral material has entered through water and deposited silica within the cavities to replace the organic material over time) Time and Space • Phylogeny refers to the evolutionary history of a group of organisms, or, as Darwin wrote, “descent with modification” ◦ all organisms have a common ancestor, then they undergo change due to natural selection, leading to either descendants who will continue to change, or extinction • Taxonomy and Humans ◦ taxonomy chart ◦ Homo sapiens, Homo, Hominids, Primates, Mammalia, Chordata, Animalia, Eukarya • Paleoecology uses fossils not t
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