Comparative Anatomy Vertebrate Classification Fish Evolution

1. Comparative AnatomyVertebrate ClassificationFish Evolution Note Set 3 Chapter 3

2. Vertebrate Classification • Geological eras of early vertebrates • Paleozoic (oldest) • Mesozoic • Cenozoic Figure 4.1

3. Cambrian Period • Ostracoderms- first vertebrates, shell skinned • Class Agnatha- jawless fish • No paired fins • Bony exoskeleton with dermal armor • Ex: hagfish and lampreys • Jawed fish evolved from Ostracoderms in Silurian period (a) (b) Figure 4.2: (a) ostracoderm, (b) ostracoderm, and (c) lamprey. (c)

4. Lower vs. Higher Organisms • Echinoderm-like organism (deuterostomes) gave rise to vertebrates • Deuterostomes- blastopore gives rise to anus • Protostomes- blastopore gives rise to mouth (a) (b) Figure 4.3- (a) protostomes and (b) deuterostomes.

5. Placoderms • Class Placodermii • Jawed and paired fins • Bony dermal exoskeleton; armored fish • 1st jaws were large • Jawed fishes gave rise to all other fishes • Age of fishes- Devonian Period Figure 4.4- Armored fish Figure 4.5- mandibular (ma) and hyoid (hy) arches develop in gnathostomes into palatoquadrate (pq) and Meckel’s (Mc) cartilages

6. Fish Evolution (a) (b) Figure 4.6: (a) jawless fish, (b) early jawed fish, and (c) modern jawed fish (c)

7. Placoderms • Anadromous- fish move to freshwater to breed • Catadromous- fish move from freshwater to breed • Hypothesized function of bone- to provide calcium for muscle contraction Figure 4.7: Craniates through geological time.

8. Fish • Chondrichthyes • Cartilaginous skeleton • Bone remains in scales- placoid scales • Teeth are modified scales • Ex: sharks, rays, skates Figure 4.8: Shark

9. Tail Type • Heterocercal- vertebral axis curves upward; two asymmetrical lobes (dorsal portion larger) • More primitive, some bony fish • Ex: sharks • Homocercal- symmetrical dorsal and ventral lobes • Most common • Ex: perch • Diphycercal- spear shaped • Ex: lungfish, crossepterygians Figure 4.9

10. Class Osteichthyes • Subclass Actinopterygii (ray-finned) • Chondrostei- most primitive; heterocercal tail • Ex: sturgeon, paddlefish, Polypterus • Holostei- dominant in past; heterocercal tail • Ex: gar, bowfin • Teleostei- dominant today; homocercal tail • Majority of all fish Figure 4.10- us lionfish (actinopterygian).

11. Evolutionary relationship of vertebrates with jaws (gnathostomata) to those with bony skeleton (osteichthyes) Figure 4.11

12. Class Osteichthyes • Subclass Sarcopterygii (fleshy or lobe finned) • 3 genera of lungfish appeared on 3 separate continents • Continental Drift • Torpidity- inactivity; hibernation • Aestivation- burrow through dry season • Order Dipnoi • Order Crossopterygii Figure 4.12: Aestivation; fish burrows into mud until rain returns.

13. Order Crossopterygii • Living fossil • Species thought to be extinct until coelacanth (Latimeria) • Found off coast of South Africa in 1938 • Separate species discovered off Indonesia in 1999 Figure 4.13: Global locations of coelacanth discoveries.

14. Coelacanth Figure 4.14: Coelacanth in Indian Ocean.

15. Coelacanth Figure 4.15 Figure 4.16- Africa’s Sunday Times.

16. Crossopterygiians (lobe-finned fish) gave rise to Labyrinthodonts (early amphibians) in Devonian Period Figure 4.17: Labyrinthodont

17. Linking Evidence • Skulls • Parietal foramen • Crossoterygii skull shows place for third eye • Third (pineal) eye visible in young tuatara reptiles • Tooth structure • Labyrinthodont tooth Figure 4.18: Crossopterygii skull. Figure 4.19: Grooved tooth.

18. Linking Evidence • Limbs evolved • Vertebrae • Girdles similar • Fin’s skeletal composition exhibits homology with early amphibians • Amphibian diversity during Carboniferous period • Toward reptiles, Anura, Caudata, and Apoda Figure 4.20 Figure 4.21

19. Amphibian Characteristics • 1st to possess cervical vertebrae • Lost scales • Primitive frogs have dermal scales • Anamniotic eggs • 3 chambered heart • Metamorphosis • 10 pairs of cranial nerves • 2 occipital condyles

20. Apoda • Caecilians • Long and slim; segmented rings • Dermal bones (scales) embedded in annuli Figure 4.22

21. Literature Cited Figure 4.1- http://custance.org/Library/Volume2/Part_V/Chapter2.html Figure 4.2(a)- http://www.alientravelguide.com/science/biology/life/ostracod.htm Figure 4.2(b)- http://www.zoology.ubc.ca/courses/bio204/lab5_photos.htm Figure 4.2(c)-http://www.ohiodnr.com/dnap/rivfish/ohiolamp.html Figure 4.3-Kardong, K. Vertebrates: Comparative Anatomy, Function, Evolution. McGraw Hill, 2002. Figure 4.4- http://www.ucmp.berkeley.edu/vertebrates/basalfish/placodermi.html Figure 4.5- http://www.origins.tv/darwin/jaws.htm Figure 4.6- http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookDiversity_9.html Figure 4.7- Kent, George C. and Robert K. Carr. Comparative Anatomy of the Vertebrates. 9th ed. McGraw-Hill, 2001. Figure 4.8- http://www.bio.miami.edu/dana/106/106F04_17.html Figure 4.9- http://departments.juniata.edu/biology/vertzoo/fish_lab.htm Figure 4.10- http://www.anselm.edu/homepage/jpitocch/genbios/vertevol.html Figure 4.11- http://www.geol.umd.edu/~jmerck/eltsite01/reading/eltsysex/sysq6.gif Figure 4.12- http://malawicichlids.com/mw11001a.htm Figure 4.14- Gorr, Thomas and Traute Kleinschmidt. Evolutionary Relationships of the Coelacanth. American Scientist. Vol. 81, No. 1: Sigma Xi, 1993. Figure 4.13 &115- http://news.bbc.co.uk/1/hi/sci/tech/302368.stm Figure 4.16- http://www.suntimes.co.za/specialreports/zimbabwe/?MenuItem=s0 Figure 4.17- http://faculty.uca.edu/~benw/biol4402/lecture8c/img016.jpg Figure 4.18- http://www.palaeos.com/Vertebrates/Units/140Sarcopterygii/140.400.html Figure 4.19- http://www-biol.paisley.ac.uk/biomedia/gallery/labyrinthodont.htm Figure 4.20- http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookDiversity_9.html Figure 4.21- http://people.eku.edu/ritchisong/342notes1.htm Figure 4.22- http://elib.cs.berkeley.edu/aw/lists/Caeciliidae.shtml