GEOL 101 Fossils and Multi-cellular Life
GEOL 101 Fossils and Multi-cellular Life GEOL 101
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This 4 page Class Notes was uploaded by Victoria Williams on Wednesday May 4, 2016. The Class Notes belongs to GEOL 101 at George Mason University taught by Mark Uhen in Fall 2016. Since its upload, it has received 13 views. For similar materials see Introductory Geology in Geology at George Mason University.
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Date Created: 05/04/16
Multicellular Life How old is the oldest multicellular creature? 1 billion years old. Fossils are any evidence of ancient life: petrified wood, amber, animal bone impressions, and coprolites (poop) What is evolution? Dissent with modification. Change over time. Natural Selection is a threestep process: production of heritable variation, differential reproduction (selection), and inheritance. One way that organisms evolve. Traits are not always beneficial and they’re not always bad. For example, beetles living on a tree are green and brown in color. This population lives on the bark, and the green beetles get eaten because they can be seen. If this population had been living in the leaves, the green would survive and the brown would be picked by predators. Diversity – the number of taxa over time. Speciation – The splitting of one lineage into two or more lineages. Speciation often occurs when some individuals of a species are geographically separated from other members of their species and they diverge over time. Extinction is the death of all individuals in a species or higher taxon. There are two types of extinction. Background extinction is the constant process of species going extinct over time. Mass extinction is the termination of many unrelated species at the same time. Background extinction is the normal extinction rate that is the sum of all extinctions that occur over time due to the constant changes in climate, geography, and biological communities. Geologic Time Scales are set based on mass extinction. Mass extinction are peaks in the rate of extinction that are far above the background extinction rates. Cnidaria: Corals o Stinging Cells o CaCO skeleton 3 o Radial Symmetry o Often colonial, living together. They’re often clones of each other in one tight area. o PrecambrianRecent Arthropods: Trilobites o Marine o Detritivore o Jointed Limbs o 3 Lobes o 3 Segments (head/cephalon, thorax, tail/pygidium) o Paleozoic Arthopoda: Crustacea o Marine, freshwater o Usually carnivorous o Calcified Chitin o 2 Segments (head/body, abdomen) o Paleozoic – Recent Arthopoda: Incecta o Terrestrial exclusive o Range of feeding types o Chitin exoskeleton o 3 Segments o Paleozoic (Devonian) – Recent o Usually preserved in carbon films Mollusca: Pelecypoda o Marine, freshwater o Filter feed o CaCO3 shell o Usually symmetrical through the hinge line o PaleozoicRecent o Like shells/mollusks/clams today Mollusca: Gastropoda o Marine, freshwater, terrestrial o Active feeders – Radula (similar to teeth) used to eat o CaCO3 shell o Single Shell, usually coiled, torsion o PaleozoicRecent o Can escape within their shells that close with ‘operculum’ flap Mollusca: Monoplacophora o Marine o Filter Feeders o CaCO3 Shell o Thought to be extinct, only found in fossils. But they were found alive in deep sea trenches. o Bilaterally symmetrical o Single, uncoiled shell o PaleozoicRecent Mollusca: Cephlapoda o Parine, freshwater o Active feeders o CaCO3 shell o Single shell, usually coiled, torsion o PaleozoicRecent o Examples: Cephalopods (in shell), Squids, Cuttlefish, Octopus (no shell remnant) Hyolitha o Marine o Detritus feeders o CaCO3 Shell o Extinct o It is unknown how they really function o Not very diverse o Two shells plus helenes o Paleozoic Brachiopoda o Marine o Filter feeders (open shell, pump water over lophophore, feed, spit water out) o CaCO3 or CaPO4 shell o Two shells, symmetrical across hinge (symmetrical left to right, but the two sides up and down are not symmetrical) o Diversity went down after one mass extinction o PaleozoicRecent Bryozoa o Marine o Filter feeders o CaCO3 Skeleton o Colonial o OrdovicianRecent o Very small, but they live in colonies, each individual is a clone of others, individual is called a zooid Echinodermata o Marine o Various feeding modes o CaCO3 Skeleton o Pentameral symmetry (symmetrical in 5’s, or multiples of 5) o PaleozoicRecent o Examples today are starfish, sea cucumbers, sea lily, sea star, sand dollars. Plantae o Terrestrial, freshwater, marine o Photosynthetic o Paleozoic (Silurian)Recent o First plants were super simple, basically ‘sticks’ with little buds to reproduce Plants: Seed Ferns o Terrestrial, treelike o Photosynthetic o Reproduced with seeds o Found on southern continents Plants: Flowering Plants o Terrestrial o Photosynthetic o Produce flowers and fruit o Cretaceous to recent o Dominate plant species today o Mesozoic (Cretaceous)Recent Chordata: o Marine, freshwater o Various feeding modes o Lay eggs in water o Breath with gills o Paleozoicrecent Chordata: Amphibians o Freshwater, terrestrial o Various feeding modes o Lays eggs in water o Gills and lungs o PaleozoicRecent Chordata: Reptilia o Marine, freshwater, terrestrial o Various feeding modes o Lays eggs on land (eggs have shells) o Lungs o PaleozoicRecent o Turtles, crocodiles Chordata: Dinosauria o Terrestrial o Various feeding modes o Lay eggs on land o Small to huge in size o Mesozoic (Triassic)Recent (inc. Avian/Birds) Chordata: Aves o Marine, freshwater, terrestrial o Various feeding modes o Used to have teeth and long bony tails like dinosaurs, but evolved out of it o Lay eggs on land o Hollow bones with air sacs o Mesozoicrecent Chordata: Mammalia o Terrestrial, freshwater, marine o Various feeding modes – very particular teeth, two sets (baby and teeth) o Most give live birth o Endothermic – develop hair/fur o Evolved like crazy after dinosaur’s extinction with new land freedom o Mesozoic (Triassic)Recent
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