Understanding Fossils and Dating Methods in Human Origins

ANTH 161 Name ________________________ Human Origins Section _____________________ Lab 8 Fossils and Dating Exercise 1: Vocabulary Please define these terms in your own words : • Paleontologist: Someone who studies the history of life through the fossil record • Fossil: the remains of something or an impression of a pre-historic organism that has been preserved • Anaerobic: it means to be without oxygen, and it keep bacteria from decomposing fossils • Permineralization: this happens when minerals transferred from water fill the open spaces of an organism or its tissue making internal casts. • Taphonomy: it’s the study of what has happened from the date of the fossil to the discover from the paleontologist through factors such as wind, water, temperature, ect • The Law of Superposition: the layers of the ground that show us different ages the deeper the layer the older. However, the strata do not always stay in the same place • Strata: a layer of rocks or sediment which can help identify how old fossils are • Relative and Absolute Dating: relative dating is done through the other fossils near the object to create a possible date of a fossil then absolute dating finds the specific calendar year. • Half Life: the number of years it takes for half of the radioactive isotope to decay • Biostratigraphy: The law of animal succession. • Radiometric Dating: this method uses radioactive elements to find out the possible age of rocks or fossils. • Context: this could relate too where a fossil was found and using information such as the strata or other fossils found nearby can help to determine its age or other conclusions. • Paleoenvironment: the study of how the environment looked in the past Page 1 of 5

ANTH 161 Name ________________________ Human Origins Section _____________________ Exercise 2 : Dating Methods Fill in the chart on the next page with details about the different dating methods. Read and use the information packet on blackboard to answer these questions . Page 2 of 5

ANTH 161 Name ________________________ Human Origins Section _____________________ Absolute or Relative Half Life Dating Range Datable Materials Issues? Stratigraphy Relative N/A N/A Pebbles, sand, and dust The strata does not always stay in their original position Biostratigraphy Relative N/A N/A Fossil fauna N/A they are consistent regardless of strata K/Ar Absolute 1.3 billion years billions of years old Volcanic sediments Only accurate in more recent sediments Ar/Ar Relative N/A Used within a standard of a known age Argon decay Can only give relative age C14 absolute 5730 years Most accurate up to 40,000, while some go to 70,000 years Bone, wood, seeds, and teeth Is only accurate up to 40,000 years U-series absolute Maximum of 245,000 years 500,000 years Most successful in calcium, ideal for limestone Isn’t as accurate in non- calcium findings ESR Relative N/A 500,000 to 3 million years Teeth, stone tools, and pottery Human teeth are small, so tests are usually done on animals with big teeth OSL absolute N/A 1,000 to 400,000 years N/A Not as useful dating very early fossils hominins Paleomagneometry Relative N/A N/A N/A N/A Page 3 of 5

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ANTH 161 Name ________________________ Human Origins Section _____________________ Exercise 3: Stratigraphy The graphic below is a stratigraphic profile of an archaeological site. Its natural horizontal strata have been complicated by human activity such as digging pits and construction . In this exercise you will sort out the stratigraphy and use stratigraphic principles to date the artifacts in the site *Note : Early = the oldest and deepest layer Later = the newest and layer closest to the surface Stratigraphic layers are numbered A-V; Burials are W-Z; Ceramic vessels (pots) are 1-7 Questions 1. Which stratum is earlier: C or E? E 2. Is it possible to determine which ceramic vessel is later: 4, 5, or 6? If so, which one? 6 3. Is it possible to determine which vessel is earlier: 1, 2, 6, or 7? If so, which one? 7, because it’s the deepest however 6 could be close knowing relative date and since it is in the same layer. 4. In what order were the burials interred? X W Y Z 5. Which is older: Burial Y or Vessel 3? 3 Page 4 of 5

ANTH 161 Name ________________________ Human Origins Section _____________________ 6. Was the wall built before or after burial Y was interred? before Page 5 of 5

Lab 8. Fossils and Dating Methods (Virtual) Anya Baltenbach

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