of 12

  • date post

  • Category


  • view

  • download


Embed Size (px)


VERTEBRATE ZOOLOGY (VZ Lecture03 – Spring 2012 Althoff - reference PJH Chapters 1,2 & 7). DIVERSITY, CLASSIFICATION & EVOLUTION PART III. Two Embryonic Features that may account for difference between vertebrates and other chordates. - PowerPoint PPT Presentation


  • DIVERSITY, CLASSIFICATION & EVOLUTIONPART IIIVERTEBRATE ZOOLOGY (VZ Lecture03 Spring 2012 Althoff - reference PJH Chapters 1,2 & 7)

  • Two Embryonic Features that may account for difference betweenvertebrates and other chordatesIn vertebrates: development of tissue called ______________. Forms many new structures found only in vertebrates

    Duplication of the ______________________

  • chicken embryoI migrates to form mandibleIImigrates to form hyoid apparatusIII & IVmigrate to form outflow tract of heart_______________ migrating to branchial arches1

  • Neural Crest CellsOriginally thought that neural crest was derived from ectoderm germ layerRecently (Hall 2000) proposed that neural crest actually is a truly independent germ layernot part of ecto-, endo-, or mesoderm. If true.Vertebrates are the only animals that have __ germ layers making them ____________Helps explain significant advancement in variety of structures in true vertebrates


  • Hox gene complex= Homeobox genes that characterize animalsDont code for specific features, but regulate expression of the hierarchy of other genes that control the shape of the bodyJellyfishes 1 or 2 Hox genes Echinoderms & Nonvertebrate Chordates 7 up to 13 vs. Vertebrates which have undergone ___________ of entire Hox complex2

  • Hox gene complexcontSo, what is the minimum number of Hox genes in vertebrates? Likely ____Mammals appear to have ____ such genesBottomline: More complex animals usually have a greater amount of genetic materialand it is thought that the ________ of this gene sequence at the _______ of vertebrate evolution made possible the evolution of a more complex type of animalPough, Janis, & Heiser 2005

  • Early History & Vertebrate EvolutionVertebrates first appeared in the early Paleozic, about 540 MYA.earth at the time was mostly water covered, extensive continental movements, and an O2 rich atmosphere formed as a result of ________________________ of autotrophs Movement of land masses and climatic differences/changes resulted in major evolutionary effects on vertebrates.


  • Early History: PALEOZOICVertebrates first appeared in the early Paleozoic, about ~________.earth at the time was mostly water covered, extensive continental movements, and an O2 rich (in relative terms) atmosphere.490 MYA 443 MYA many shallow seas appeared, allowed for major radiation among marine animals, followed by first appearance of primitive vertebratesprimarily _____________, followed by _______________

  • Early History: PALEOZOICcont443 417 MYA vascular plants and arthropods just starting to appear, Jawless fishes continued to radiate and jawed fishes (including sharklike forms) appeared417 354 MYA major freshwater basins appeared with first tetrapods. End of this period marked by disappearance of ________________ ____________ (ostracoderms)354 290 MYA major glaciation. First appearance of ___________ and modern types of jawless fishes. Extensive radiation of non-amniote tetrapods. First __________ appeared.

  • Early History: PALEOZOICcont290 251 MYA Single continent (Pangea) formed near end of this period.-largest non-amniote tetrapods declined-amniotes radiatedmodern reptilesmammal-like reptilesfirst known ___________ tetrapodsLargest known ______________ event occurred at end of periodimpacting both land and sea fauna: THE END OF THE PALEOZOIC

  • MESOZOIC251 206 MYA Single continent high, few shallow seas, no evidence of glaciationmammal-like reptiles declinedarchosaurian reptiles (including dinosaur ancestors) diversifiedall large nonamniote tetrapods now aquatic formstrue mammals appeardinosaurs, pterousaurs, marine reptiles, crocodiles, lepidosaurs, frog-likeamphibians, and teleost fishes appear206 144 MYA Continent breakup. Modern sharks and rays appear._________________________________

  • PALEOZOIC (late Carboniferous Period)

    AquaticnonamniotetetrapodsTerrestrialnonamniotetetrapods 12345Fig. 7-5 p165 PJH