212.1 The Fossil RecordSpecific environmental conditions are necessary in order for fossils to form.
3Fossils can form in several ways. 12.1 The Fossil RecordFossils can form in several ways.Permineralization occurs when minerals carried by water are deposited around a hard structure.
4Fossils can form in several ways. 12.1 The Fossil RecordFossils can form in several ways.A natural cast forms when flowing water removes all of the original tissue, leaving an impression.
5Fossils can form in several ways. 12.1 The Fossil RecordFossils can form in several ways.Trace fossils record the activity of an organism.
6Fossils can form in several ways. 12.1 The Fossil RecordFossils can form in several ways.Amber-preserved fossils are organisms that become trapped in tree resin that hardens after the tree is buried.
7Fossils can form in several ways. 12.1 The Fossil RecordFossils can form in several ways.Preserved remains form when an entire organism becomes encased in material such as ice.
812.1 The Fossil RecordSpecific conditions are needed for fossilization.Only a tiny percentage of living things became fossils.
912.1 The Fossil RecordRadiometric dating provides an accurate way to estimate the age of fossils.Relative dating estimates the time during which an organism lived.It compares the placement of fossils in layers of rock.Scientists infer the order in which species existed.
1012.1 The Fossil RecordRadiometric dating uses decay of unstable isotopes.Isotopes are atoms of an element that differ in their number of neutrons.A half-life is the amount of time it takes for half of the isotope to decay.
11The geologic time scale divides Earth’s history based on major past events.
12Geologic Time Scale Is a representation of the history of the Earth Organizes Earth’s history by major changes or events that have occurred, using evidence from the fossil and geologic records.
13Organization of the Geologic Time Scale Divided into a series of units based on the order in which different groups of rocks and fossils were formed.
143 basic units: Eras- Periods- Epochs- last tens to hundreds of millions of yearsconsist of two or more periodsthree eras: Cenozoic, Mesozoic, PaleozoicPeriods-most commonly used units of time on the scalelasting tens of millions of yearsEach period is associated with a particular type of rock system.Epochs-smallest units of geologic timelast several million years
16Paleozoic EraMulticellular organisms first appeared during the Paleozoic era.The era began 544 million years ago and ended 248 million years ago.The Cambrian explosion led to a huge diversity of animal species.
17Mesozoic era known as the Age of Reptiles. It began 248 million years ago and ended 65 million years ago.Dinosaurs, birds, flowering plants, and first mammals appeared during this time.
18Cenozoic era First appearance of mammals The Cenozoic era began 65 million years ago and continues today.Placental mammals and monotremes (lay eggs) evolved and diversified.Anatomically modern humans appeared late in the era.
20PrimatesPrimates are mammals with flexible hands and feet, forward-looking eyes and enlarged brains.Also have arms that can rotate in a circle around their shoulder joint, as well as thumbs that can move against their fingers.Include:Lemurs, monkeys, apes and humansPrimates share physical traits and molecular similarities.
22Evolutionary Relationships of Primates Primates are divided into 2 groups:AnthropoidsProsimiansAnthropoids are divided into:HominoidsMonkeysHominoids are divided into:Lesser apes (gibbons)Great apes (orangutans, chimpanzees, and gorillas)Hominids (include humans)
24Hominid Species Classified into 2 groups: Australopithecus afarensis genus Australopithecusgenus HomoAustralopithecus afarensisLived 3-4 million yrs ago in AfricaSmaller brain, humanlike limbsHomo habilisLived million yrs ago in modern day Kenya and TanzaniaEarliest known hominid to make stone toolsBrain was larger and shape was more similar to that of a modern human
25Hominid Species Homo neanderthalensis Homo sapiens Lived 200,000 to 300,000 yrs ago in Europe and Middle EastHomo sapiensIncludes modern humansFirst appeared in Ethiopia around 100,000 yrs ago ( according to fossils found there)Different features from modern humansProof that the species did not stop evolving
26Examples of Hominid Skulls AustralopithecusafarensisHomo habilisHomoneanderthalensisHomo sapiens
27Assignment Draw the Geologic Time Scale (pg 367) You will need a few sheets of paper and markers/colored pencils, maybe a ruler.Please include the following on your time scale:All eras and periodsThe years for eachBrief description of what happened on Earth during that time, animals, extinctions, etc.PICTURES!!!BE CREATIVE!!! You HAVE to use color and pictures!!!! NO EXCEPTIONS!!!!!!