ISB 11-02-07 - ISB 200 History of Life 11/02/07 Brachiopods...

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ISB 200 – History of Life – 11/02/07 Brachiopods o Dominated the bottom part of the ocean during the early days of the oceans o are a nearly extinct, small phylum of benthic invertebrates Cephalopods o Limit to how thick the shell is Trilobites o are extinct arthropods o marvelous spines Eurypterids o was the largest known arthropod that ever lived o known as sea scorpions o primary marine predators of their time until fish came along o fish changed the composition of the marine environment Crinoids o Like a star fish on a stalk o They are capable of breaking off the stalk that keeps it in place, it has the ability to reattach the stalk somewhere else o The ones that can move this stalk are more common than the ones that cant o Crinoids are characterized by a mouth on the top surface that is surrounded by feeding arms Cambrian Period (554-505 MY) Ordovician Period (505-438 MY) Silurian Period (438-408 MY) Devonian Period (408-360 MY) o First time we see fish
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o Fish change the characteristic of the marine environment Beaches of NW Michigan o Petoskey Stone Fossil coral Fossil comes from the Devonian period Agnatha o Most primitive fish still alive are jawless fish o Elongated bodies o Can survive in fresh water Ostracoderms o Wore heavy armor so it was hard for them to swim o Bottom dwelling scum suckers Placoderms o Jaws = serious predators o the first of the jawed fish, their jaws likely evolving from the first of their gill arches single most important evolution in fish Chondrichthyes o Sharks and rays o are jawed fish with paired fins, paired nostrils, scales, two-chambered hearts, and skeletons made of cartilage rather than bone o their only significant enemy is us Teleost Fishes o Internal skeleton is bone, some cartilage o Ray-finned Crossopterygians o Fins do not originate out of the body walls
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o Lobe-finned, fresh water fish o They are ancestral to the first land animals o Fresh water fish are closer connected to the first land animals than sea water fish o They are still alive and in deep salt water ISB 200 – History of Life – 11/05/07 Pre-adaptation o An adaption that develops before its needed o Something that is designed for something else turns out to be useful for another thing as well o #1 pre-adaption are the lobe on the lobe-fin fishes, which turn out to change into legs Lungs o Fish with lungs are called Lung Fish o They are all through the southern continents o This “lung” regulates the buoyancy of the fish, allows the fish to just sit there if they just stop swimming o Gas is released/ and taken in from the swim bladder using the circulatory system o Australian Lungfish, for these fish the swim bladder actually acts as a real lung Typically in the area these fish live at they have dry seasons During these drought parts the lungfish covers themselves in mud and hibernate until the river starts to flow again Lobe-finned lung fish is the No. 1 pre-adaption for the Devonian period
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ISB 11-02-07 - ISB 200 History of Life 11/02/07 Brachiopods...

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