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31 Cards in this Set
- Front
- Back
Other types of fossils (2) w/example
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Trace fossils
• Animal tracks Coprolites • Fossilized feces |
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5 Types of Relative Dating
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• Lithostratigraphy
• Tephrostratigraphy • Biostratigraphy • Chemical signatures within sites • Geomagnetic polarity |
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3 Types of Chronometric Dating
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• Dendrochronology
• Radiometric Dating • Electron Trap Techniques |
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Isotope Dating
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• Unstable nuclide
• Carbon 12 (stable) • Carbon 13 (stable) • Carbon 14 (unstable- radioactive) |
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Lithostratigraphy
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Comparing/contrasting of layers of Stratigraphy at different sites
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Tephrostratigraphy
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Looks at chemical signatures of deposits
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Biostratigraphy
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Examines index fossils to deduce an age range
Chemical signatures within sites Association of fossils Same age fossils should have the same ratio Note: only useful for comparisons within a site |
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Geomagnetic polarity
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• Calibrated relative dating
o Polarity of earth’s magnetic field o Has alternated through time o Rocks form under different fields • Geomagnetic Polarity time scale (GPTS) |
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Radiometric Dating
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• Unstable isotopes
• Clock-like decay • Very old samples • Half-life= time for ½ parent sample to decay into daughter sample |
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Potassium-argon (K-Ar) & argon-argon (40Ar/39Ar)
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• Decay of 40K to 40Ar
• Half-life= 1.3 billion years • Age range= 10,000- 4.5billion years • K-bearing mineral • Volcanic sediments • Eruptions resets argon clock • Fossils found in sediments between sediments |
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Fission-Track Dating
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• 238U
• Obsidian, mica, zircon crystals • Geological strata • Decay process leaves tracks • Number of tracks proportional to time |
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Radio Carbon Dating (C14 dating)
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• Organic Materials
• Charcoal, wood, bone, shell • <40,000 years • due to short half-life • Estimates time since death |
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Thermoluminescence
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Electrons of quartz, feldspar, diamond, calcite crystals are displaced and trapped
Accumulation over 100k-500k years Heat releases electrons and the Stored energy is emitted in the form of light impulses |
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Electron Spin Resonance (ESR)
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• Calcium carbonate in limestone, fossil teeth, quartz, flint
• 300,000 years or less • Sample is not destroyed • Spin causes a change in the magnetic field of atoms o Provides a clock • Used with other methods to corroborate dates |
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Carpolestidae
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Carpolestes
Paleocene • Arboreal adaptations • Nails instead of claws • Opposable big toes o Some primate traits—a proto primate |
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Necrolemur
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• Michrochoerinae
• Late Eocene • Resemble Tarsiers o Leaping adaptations similar to tarsiers • Fused tibia and fibula |
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Darwinius masillae
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Adapidae; Cercamoniines
Eocene Primate • Extremely diverse • Early Eocene to Early Oligocene • North America, Africa and Asia • Anchomomys Sole primate survivor of the Grand Coupre in Europe o Almost complete, well preserved fossil o Messel, Germany o 47 mya |
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New selective pressures in Miocene
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o Diversification of Old World Monkeys
• Colobines and Cerropithecines o Ape-Monkey divergence • Pongid radiation |
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Anatomical traits of a Biped
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Foramen magnum directly beneath the skull (chimps posteriorly located)
S-Shaped (sigmoid) curve with lumbar lordosis Bowl shaped pelvis with Short, broad ilium • Broad sacro-iliac joint • Anterior iliac spine Large femoral head Thick femoral neck Longer medial condyle Medially angled femur Robust calcaneus (heel bone) Long tarsals (increases power, length) Non-divergent hallux Shortened, flat phalanges Longitudinal arches |
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Pleisadapiforms
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Archaic Primate?
Purgatoriidae o Purgatorius • Early Paleocene (65mya) • Bug Creek Anthills, Montana • Possible nails instead of claws Plesiadapidae o Pleisiadapis • Big Horn Basin • Also in Europe o Large rodent-like incisors • No gnawing • Leaves and fruits Carpolestidae o Carpolestes • Clark Fork Basin, WY • Arboreal adaptations • Nails instead of claws • Opposable big toes • Vegetation, fruits, nuts o Some primate traits—a proto primate |
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Cantius
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• Norharctinae
o Oldest indisputable euprimate o 2:1:4:3 dental formula |
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Fayum Depression
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Egypt
Oligocene • Lushly forested in the Eocene/Oligocene boundary |
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Dental Apes
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• The earliest apes
o ~27mya o Y-5 Dentition o Ape like dentition, but monkey-like skeleton o Proconsul • 18-20mya • Best known dental ape |
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Branisella
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• Early Platyrrhines
o ~25-30mya • Bolivia • Small Frugivores • May represent the first platyrrhines radiation o How did they get to the new world? • Probably arrived in late Eocene • Arrived via drift across Atlantic |
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The Pliocene
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• 5-2mya
• Adaptive radiation of Hominids o Bipedality o Increased brain size • Neuronal reorganization • Behavioral changes o A mosaic of evolutionary process |
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The Miocene
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• Miocene (22-5mya)
o Ape Radiation (Homonoids) o Sivapithecus o Gigantopithecus o Proconsul o Dropithecus Climate Change o Warmer, wetter than Oligocene o New migration routes Hominoid (Ape) Radiation o The “Golden Age”- more than today o Africa, Asia, Europe Late Miocene o Divergence of Chimp and Human ancestors |
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Characteristics of Anthropoid Primates
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• Complete post orbital closure
• Fused frontal bone and mandibular symphisis • Lacrimal bone located in the eye, not the snout • Larger body size • Diurnal |
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Eocene
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Initial adaptive radiation of primates
Warming period, followed by a cooling period General extincion of the plesiadapiforms; replaced by euprimates Strepsirrhini and Haplorrhini split Superfamiles • Adapoidia • Omomyoidea |
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Oligocene
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Geological Processes
Cooling, drying trend New selective pressures Fayum depression of Egypt Anthropoid/Oligiopithecidae/Parapithecidae/Propliopithecidae/Early Platyrrhines |
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Ape Characteristics
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• Dorsally placed scapulae
• Broad shallow rib cage/thorax • Long forelimbs with curved phalanges o Adaptations for suspensory behavior • Reduced olecronon process (elbow/humerus) • 5-Y lower molar pattern |
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Principles of Stratigraphy
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o Principle of horizontality
o Principle of superposition o Principle of cross-cutting relationships o Principle of faunal succession • Index fossils: fossils that are wide-spread but are clearly extinct in later layers |