Summer 2006 Workshop in Biology and Multimedia for High School Teachers

Earth History - The Geologic Time Scale Laurie St.Pierre Sandwich High School Sandwich, MA

The Age of the Earth 4.6 billion years old = 4,600,000,000 Image courtesy of NASA, http://en.wikipedia.org/wiki/Image:The_Earth_seen_from_Apollo_17.jpg#file

The earth’s 4.6 billion year history is divided into major units of time: Precambrian Time Paleozoic Era Mesozoic Era Cenozoic Era Image created by Jason Brechko for Lake George Association (Lake George, NY) http://www.lakegeorgeassociation.org/geology_facts.htm

Precambrian Time 4.6 billion years before present to 544 million years before present Longest era with a sparse fossil record Origin of earth’s crust, first atmosphere, and first seas Earliest fossils of cyanobacteria use photosynthesis to produce oxygen Ozone layer in the atmosphere is formed from oxygen Image courtesy of http://www.sharkbay.wa.gov.au/tourism/what_to_see_and_do/images/stromatolites_lge.jpg Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

Paleozoic era 544 million years before present to 245 million years before present Marine communities flourish Early fishes develop Origin of amphibians, insects & reptiles Recurring ice ages/ Appalachians mountains form Spore-bearing plants dominate Images courtesy of: http://discover.edventures.com/images/termlib/p/paleozoic/support.gif, http://en.wikipedia.org/wiki/Trilobites Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

Paleozoic era (continued)… 286 - 248 million years before present: Supercontinent of Pangea forms 248 million years before present: MASS EXTINCTION-90 % of all known families lost! c Image courtesy of http://www.ig.utexas.edu/research/projects/plates/teaching_ideas.htm?PHPSESSID=def1b9 Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

Image courtesy of http://nascarulz.tripod.com/dinomain.html Mesozoic Era 245 million years before present - 65 million years before present The age of the dinosaurs! Gymnosperms dominate land plant/ origin of angiosperms - flowering plants Origin of mammals & birds 145 million years before present - asteroid impact? MASS EXTINCTION Pangea begins to separate/ Rocky mountains form Image courtesy of http://nascarulz.tripod.com/dinomain.html Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

65 million years before present…. ASTEROID IMPACT! Mass extinction of ALL dinosaurs and many marine organisms End of the Mesozoic era Image courtesy of NASA: http://www.nasaexplores.com/show2_912a.php?id=01-074&gl=912 Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

Image courtesy of: http://www.karencarr.com/gallery_Cenozoic_arch.html Cenozoic Era 65 million years before present - today Present era we live in Continued evolution and adaptations of flowering plants, insects, birds, mammals Mammals dominant Major crustal movements & mountain building (Alps & Himalayan mountains form) Image courtesy of: http://www.karencarr.com/gallery_Cenozoic_arch.html Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.

And during the Cenozoic era… The most primitive hominid (human ancestor) evolves - approximately 4.4million years before present The first modern humans (homo sapiens) evolved approximately 100,000 years before present Image courtesy of: http://www.wilderdom.com/images/evolution/8.jpg