Presentation on theme: "Intro to Evolution Evolution simply means change over time."— Presentation transcript:
1Intro to Evolution Evolution simply means change over time. many things evolve, including languages, and your view of the world.
2Intro to Evolution This unit is meant to introduce you to: the development of current evolutionary theory and subtopicsprocesses which influence the change of species over timeThis unit is not meant to:tell you what you have to believe
3Intro to EvolutionThis unit is a spectacular view into what science truly is:we are constantly learning new things on our own and from othersmaking mistakes and learning from themmaking revisions based on new dataimproving on techniques that work or don’t work at all.taking data and attempting to determine its meaningfiguring out the “how” of things
4Timeline, Fossils & Dating Methods Unit 5 – Lecture 1
5Evolutionary Timeline The evolutionary timeline is divided into sections of time called eras – which are then divided into smaller units of time called periods.units of time are determined through use of radiometric dating methods, fossil/rock identification, and geographic strata [rock layers].evolutionists estimate the age of the earth to be approximately 4.5 billion years old
6Evol. Timeline – cont’d Hadean: 3.8-4.5 billion years ago think “Hades”very hotvery little free oxygen,lots of CO2lots of N2 [nitrogen] gaslots of water vapor
7Evol. Timeline – cont’dPrecambrian [anything from hadean to cambrian…]cyanobacteria and other prokaryotessponges & cnidarians [jellyfish/ anemone]
8Evol. Timeline – cont’d Paleozoic [542 mya – 251 mya] six periods – need to know: Cambrian [1st of six]sudden occurrence - “explosion” of life [Cambrian Explosion] seen in fossil recordworms, sea stars, trilobites, fish, reptiles…other chordates and hard-bodied organisms
9Evol. Timeline – cont’d Mesozoic [251 mya – 65 mya] three periods : Triassic – small mammalsJurassic – dinosaursCretaceous – flowering plants
10Evol. Timeline – cont’d Cenozoic: 65.5 million years ago - present lots of mammals
17Fossils – cont’d Types of Fossils: casts– mineralization of a space left by a decayed organism [most fossils you think of]molds– empty space in rock from a decayed org.
18Fossils – cont’d Types of Fossils: imprints – made typically by thin objects that have been pressed into an area
19Fossils – cont’d Types of Fossils: carbonized – high temps & pressures expel gaseous elements leaving only carbon
20Fossils – cont’d Types of Fossils: petrified – entire organism is replaced by mineral matter.
21Fossils – cont’d Types of Fossils: ice- or amber- preserved fossils [True-Form Fossils]
22Fossils – cont’d Types of Fossils: permineralization – pores are filled with mineral matter without getting rid of organic [carbon] material
23Fossils – cont’dTypes of Fossils:coprolite – fossilized dino poop
24Name and describe 5 types of fossils. DiscussName and describe 5 types of fossils.
25Fossils – cont’dWhat do we know about this fossilized organism?
26Fossils – cont’d Fossils CAN Tell Us…[sometimes] what an organism looked likewhat kinds of food it probably ateexceptions…like the panda – has very sharp teeth for eating rough bamboowhat type of area it may have lived in / climategeography of the area it lived in
27Fossils – cont’d Fossils CAN’T Tell Us… what colors an organism was almost anything about behaviorscience does attempt some basic conclusions about organisms based on how they are foundnests [nurturing], found traditionally in large groups [may have been a pack organism], etc.what it sounded likewe can make comparisons and guess at times based on structure similarities
28DiscussDiscuss with a partner certain things that we can and can’t learn from fossils.
29Dating MethodsRelative Dating – dating new samples based off of comparison to previously dated materialsuses circular reasoning:dating rocks by their fossilsdating fossils by the rock in which they are found
30Dating Methods – cont’d Relative Dating [cont’d]geologic layers as in the record are not actually found in their stated order anywhere on earth; they are approximated based on comparison of fossils and other rockthese things can lead to misinterpretation
31Dating Methods – cont’d Radiometric Dating – examining the chemical “half-life” of a substance in the sample to determine its approximate age
32Dating Methods – cont’d Radiometric Dating [cont’d]half-life – the amount of time it takes for half of a substance to change [decay] into another substancebased on isotopesisotope – atoms of an element with a different number of neutrons than is typicalthe measured isotopes are radioactive and slowly become non-reactive [this is what is measured]
34What is the difference between relative dating and radiometric dating? DiscussWhat is the difference between relative dating and radiometric dating?
35Dating Methods – cont’d Problems with Radiometric Datingmust know original amount of substance present to calculate timemust assume constant decaymust know no outside influence occurred [like water, extra heat or pressure, other substances which react]
36Dating Methods – cont’d Problems with Radiometric Datingcan’t date rocks which have been in water, but many fossils are formed in sedimentary rockin this case, rock ages are dated by the fossils found in them that have been previously identifiedrecent samples showing millions of yearsMt. St. Helens – dated 10 yrs after eruption; showed almost 3 million years datesamples showing negative age
37DiscussWhat are potential problems in relative dating and in radiometric dating?
38Science!There are ways that ALL techniques can be refined and improved – that’s the job of science – to keep learning more and going farther with research and doing many trials [when possible] to get to the most accurate data possible.To Know.
39HomeworkComplete the Stego/Horse worksheet you received.