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Remains or traces of ancient life which have been preserved by natural causes in the Earth's crust; include both remains (bones/shells) and traces (tracks)
Fossils
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Fossils that include tracks, trails, and burrows
trace fossils
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To become preserved as a fossil, an organism must:
1.) Have preservable parts (Bones, shells, teeth) 2.) Be buried by sediment to protect from scavengers/decay 3.) Escape physical/chemical/biological destruction after burial
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What characteristics are favorable for fossil preservation?
Rapid burial w/ sediment to protect from scavenging/decay and presence of hard parts
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Types of fossil preservation:
Preservation of Unaltered Hard Parts, Preservation of Unaltered Soft Parts, Chemical Alteration of Hard Parts, Imprints of Hard Parts (cast/mold), Trace fossils/Ichnofossils
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Filling of tiny pores with minerals (chemical alteration of hard parts)
Permineralization
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Molecule-by-molecule substitution of one mineral for another (chemical alteration of hard parts)
Replacement
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Aragonite alters to calcite (chemical alteration of hard parts)
Recrystallization
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Soft tissues preserved as a thin carbon film ex. ferns in shale (chemical alteration of hard parts)
Carbonization
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When mold becomes filled
Cast
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Impressions (external/internal)
Molds
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Preservation of unaltered soft parts:
Freezing, desiccation (drying/mummification), preservation in amber, tar, or peat bogs
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Markings in the sediment made by the activities of organisms
Trace fossils or Ichnofossils
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Types of trace fossils:
Tracks, trails, burrows, borings, root marks
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First: genus
Second: species
underlined/italicized; Homo sapiens
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Group of organisms that have structural, functional, developmental similarities; able to interbreed naturally; fundamental unit of biological classification
species
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Organisms are grouped based on their similarities into taxonomic groups or taxa
Taxonomy
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Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
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Classification of the human
Domain: Eukarya. Kingdom: Animalia. Phylum: Chordata. Class: Mammalia. Order: Primates. Family: Hominidae. Genus: Homo. Species: sapiens
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How many kingdoms of organisms are there? How many domains?
6 kingdoms and 3 domains
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Domain Archaea
Kingdom Archaeabacteria
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Doman Bacteria
Kingdom Eubacteria
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Doman Eukarya
Kingdom Protists, Fungi, Plantae, and Animalia
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Organic evolution
refers to changes in populations; evolution is the "great unifying theory" for understanding history of life
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Darwin's book "On The Orgin of Species" was published in:
1859
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What was the cause of variations in offspring?
Genetics
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located in nucleus of cells; consist of long DNA molecules
Chromosomes; a human has 46
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The parts of the DNA molecule that transmit hereditary traits
Genes
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The DNA molecule consists of two parallel strands (twisted ladder) and are made up of:
phosphate and sugar compounds, linked with nitrogenous bases
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Chemical changes to DNA molecule
Mutation
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Mutations can be caused by:
Chemicals, radiation, or w/out a specific causative agent; may occur in any cell, but mutation in sex cells will be passed on
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Causes of evolution- Evolution may involve change from 3 different sources:
1.) mutations 2.) gene recombination as a result of sexual reproduction 3.) natural selection
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The process through which new species arise
Speciation
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The branching of a population to produce descendants adapted to particular environments & living strategies
Adaptive radiation (ex. bird beaks)
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Gradual progressive change by means of many small steps; old idea of how evolution occured
Phyletic gradualism
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Sudden changes interrupting long periods of little change; most changes occur over short period of time
Punctuated equilibrium
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body parts with similar origin, history, and structure, but different functions
Homologous structures (hands/wings of humans, birds, whales, etc)
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organs that serve no apparent purpose, but resemble functioning organs in other animals; suggest common ancestry
Vestigial organs
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Similarity of embryos of all vertebrates suggest a common ancestry
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based on the appearance and disappearance of fossil species in the stratigraphic record
The Geologic Time Scale
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____ can also be used to correlate strata from place to place.
Fossils
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Apart from evolution & extinction, appearances and disappearances of fossils may indicate:
Changing environmental conditions that cause organisms to migrate into/out of an area or "reworked fossils"
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useful in identifying time-rock units and in correlation; diff sediments may look diff depending on conditions under which they were laid down, but may include remains of same species of fossil
Index fossils (or guide fossils)
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Characteristics of an index fossil:
1.) abundant 2.) widely distributed 3.) short geologic range
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A body of rock deposited during the time when a particular fossil organism existed; identified only on the basis of the fossils it contains.
Biozone (basic unit for biostratigraphic classification and correlation)
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The ocean may be divided into two realms:
Pelagic realm and Benthic realm
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The water mass lying above the ocean floor:
Pelagic realm
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The bottom of the sea:
Benthic realm
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Small plants and animals thatfloat, drift, or swim weakly:
Plankton
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Plants and plant-like plankton, such as diatoms and coccolithophores
Phytoplankton
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Animals and animal like plankton, such as foraminifera and radiolaria
Zooplankton
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Swimming animals that live within the water column
Nekton
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Sea-bottom dwellers:
Benthos
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Use of fossils in reconstructing ancient geography:
Note locations of fossil species of same age on map; Interpret paleoenvironment for each region using rock types/sedimentary structures/fossils; Plot environments to produce apaleogeographic map for that time interval
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The oldest fossil is _____ years old
3.5 billion; remains of simple prokaryotic cells; found in algal mats & stromatolites
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Mass extinctions occurred at the ends of the following periods:
Ordovician, Devonian (70% marine extinct), Permian (greatest extinction), Triassic, Cretaceous (dinosaurs)
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