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Geological time divisions are based on:
mass animal extinction, usually marine animals
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Main subdivisions of paleontology
- Invertebrate
- Vertebrate
- Plants
- Palynology (pollen and spores of land plants)
- Micropaleontology (marine plankton)
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Index fossils and criteria for good index fossils
- -Index fossils are used to correlate strategraphic levels of rocks from one area to another
- -Good index fossils are:
- 1. common
- 2. distinct morphologically
- 3. have a wide geographic distribution
- 4. have a narrow time distribution
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Direct vs. Indirect fossils
- - Direct fossils are body fossils, typically "hard parts" such as shells and bones
- - Indirect fossils are traces of animals like footprints
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Paleobiology
Integration of plant, animal, and other biotic evidence along with geological evidence to understand past environments
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Plant components that allow for good preservation
- - cutin in leaf
- - lignin in wood
- - sporopollenin in spore and pollen walls
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Dendrites
mineral patterns that look like fern fossils
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Compression-Impression fossils
- - show external morphology (venation and outer form)
- ...can sometimes show attachments of fruits, leaves, and branches
- ...can show details of flower parts
- - can preserve the cuticle also (waxy covering on leaf)
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Mold Casts
show outer 3D form, but lack internal structures
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Permineralization
shows internal cellular preservation
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Rock types
- - Metamorphic: formed when heat and pressure alter other rocks into other forms (aka granite)
- - Igneous: formed underground as magma, or above ground as lava from volcanic eruptions
- ...ash falls from eruptions can preserve leaf compressions and silica from volcanoes can supersaturate the ground water to permineralize plant tissues
- - Sedimentary: where you find fossils
- ...grain size determines rock type: coarse<conglomerate<sandstone<siltstone
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Sedimentology
interpret depositional environment based on patterns of rock distribution
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Depositional Environments
places where plants grow prior to fossilization
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Allochthonous
organic material transported and preserved away from the environment in which it grew originally
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Autochthonous
organic material fossilized in the same place it grew
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Permineralization process
lots of volcanic activity can produce massive amounts of silica that gets into the groundwater. The water that has totally soaked the plant tissues then becomes supersaturated or "permineralizes", catching the plant material and trapping it for us like a jello salad
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Coal
coal is the carbon from fossilized plants. It can be studied by breaking down all the organic material and looking at what is left
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Amber
amber is fossilized resin that can trap plant and insect material and preserve them
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Vegetative vs. Reproductive phases of life cycle
- - Vegetative phase begins with germination, then continues to seedling, and then to mature plant; modular and indeterminate
- - Reproductive phase begins with the flower from the mature plant and creates the seed that germinated to start the vegetative phase.
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Organs
- Leaf: photosynthesis, sometimes for attraction or modifications
- Stem: support, conduction storage, sometimes photosynthesis
- Root: anchorage, conduction storage
- Node: the point where the stem branches off to form a leaf
- Internode: empty stem between the nodes
- Indeterminate growth: growth that is not terminated, as opposed to growth that is terminated when a structure has been formed
- Axillary bud: an embryonic shoot which lies at the junction at the stem and petiole of a plant
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Organography
- - already established in the embryo
- - Shoot apical meristem: stem tip
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Main features of stem, leaf, root; radial vs. bilateral symmetry
- Stem: indeterminate, radially symmetric, phototrophic, nodes and internodes, derived from embryonic shoot apex or axillary buds
- Leaf: bilaterally symmetric, determinate, produced at nodes, ephemeral
- Root: indeterminate, radially symmetric, geotropic, lack nodes and internodes, produce a root cap
- radial symmetry is like a starfish (or flower)
- bilateral symmetry is like a butterfly
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Pith
located in the center of the stem and roots, surrounded by xylem
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Cortex
the outer layer of the stem or root bounded by epidermis on outside and endodermis on inside
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Vascular bundle
- the xylem and phloem
- xylem: transports water and some nutrients
- phloem: carried nutrients
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Phyllotaxy
leaves grow in a particular order
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Palisade and spongy mesophyll
palisade mesophyll contains chloroplasts, spongy mesopyll allows passage of gases
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Midrib
the center of the leaf containing the vascular tissue
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stomata
pores found in the leaf and stem epidermis used for gas exchange
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Transition from vegetative to reproductive phase
Changes from an indeterminate apical meristem to a determinate floral apex
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Flower and its parts
- Stigma: composed of a filament that catches pollen
- Style: structure through which the pollen tubes grow to get to the ovary
- Ovary: encloses the ovules
- Ovule: protective embryo covering; becomes the fruit
- Pistil: the ovule producing part of a flower
- Gynoecium: modified leaves or stems present on a gametophyte shoot; the innermost whorl of structures in a flower
- Stamen: pollen bearing parts of the flower (the filament and the anther that sits on top of it, collectively)
- Anther: contains pollen
- Filament: the stalk that the anther sits on top of
- Pollen: the sperm cells
- Sepals: enclose and protect the flower when in bud form
- Petals: attracts pollinators based on its bright color
- Receptacle: where the parts of the flower attach to the stalk
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What happens when the ovule becomes the seed?
The ovary and other structures becomes the fruit, and the embryo is in the seed
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Describe pollination after the pollen grain lands on the stigma
pollen contains sperm, pollen tube develops and carried sperm to egg.
- pollen is created with sperm via meiosis
- embryo sac with egg is created via meiosis
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