- August 27, 2008 Reading for Today: pgs. 10-14, 151-157,197-2 more phylogenetic terms. ng a tree synapomorphies & homologies swapping branches ng Characters of Cepahlochordates, Myxiniformes, Petromyzontiformes ata otochord, cranium, 3-part brain, nephrons, lateral line, unpaired fi s, vertebrae, jaws, gill pouches s on hagfish s on lampreys ermitting) details on jawless fossil fishes
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Lecture #2 - August 27, 2008 Reading for Today: pgs. 10-14, 151-157,197-204
Lecture #2 - August 27, 2008 Reading for Today: pgs. 10-14, 151-157,197-204 1. A few more phylogenetic terms. 2. Building a tree a. synapomorphies & homologies b. swapping branches 3. Defining Characters of Cepahlochordates, Myxiniformes, Petromyzontiformes, & Gnathostomata - PowerPoint PPT Presentation
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Lecture #2 - August 27, 2008 Reading for Today: pgs. 10-14, 151-157,197-204
1. A few more phylogenetic terms.2. Building a tree
a. synapomorphies & homologiesb. swapping branches
3. Defining Characters of Cepahlochordates, Myxiniformes, Petromyzontiformes, & Gnathostomata
Maisey, J. G. 1996. Discovering fossil fishes. HenryHolt and Co., New York.
Ostracoderms
paraphyletic group (actually two groups)
• Appeared in Cambrian/Ordovician, extinct in Devonian
• No jaws
• The first vertebrates- cartilaginous internal skeleton
• Bony exoskeleton armor-1st true bone (dermal)
• First ones were small (< 15 cm)
• No paired fins, some with reverse hypocercal tail
• Bottom dwellers
• Lots of Diverse forms
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Review Questions
1. Give the character states for notochord, cranium, 3-part brain, vertebrae,nephrons, gills/gill pouch, semi-circular canals, lateral line, jaws, paired fins,and unpaired fins for Cephalochordates, Myxiniformes, Petromyzontiformes,and Gnathostomata. Draw the phylogenetic tree and show the nodes of the tree where each character is informative. Be able to draw the same tree, but in multiple forms (i.e. rotate the branches). Be able to briefly describe each trait.
2. What evidence is there to suggest that lampreys are closely related to Cephalaspidiformes? (i.e. have you read pages 153-157)
3. Who were the conodonts and what is their significance in the evolution of fishes? List 2 or 3 things. (see Box 11.1)
Note: a possible paper topic is listed on pages 156-157 on “Later Evolution of Primitive Agnathous Fishes”.
4. Why is the placement of hagfish in vertebrates a controversy? Do you consider hagfish to be a “fish”?
5. Where do hagfish live and what are the abiotic conditions under which they are found?
Review Questions (Cont’d.)6. Describe the life-cycle of lampreys. How does this differ between parasitic and non-parasitic species?
7. Some folks have hypothesized that non-parasitic species have repeatedly evolved from parasitic species. What is the evidence for this? Assuming that this is true, draw the phylogenetic tree that this pattern would produce?
8. Compare and contrast Myxiniformes and Petromyzontiformes. Describe their habitats, distribution, heart(s), vision, pineal gland, gill pouches, vertebrae (or lack there of), and guts.
9. What is the purpose of hagfish slime? List 3-4 ideas.
10. Describe the sequence of events that happened upon the construction of the Welland Canal. Why did the construction of this canal decimate Lake Trout and Whitefish populations in Lake Michigan? What is being done to counteract this? How do the conservation efforts specifically target lampreys? What effect do you think that this might have on non-parasitic lampreys?
11. Describe the hagfish fishery that has developed in recent years.
12. Who were the Ostracaderms? In what ways were they different and in what ways were they similar to hagfish and lampreys? Who was Mayomyzon?