Comparative Anatomy Vertebrate Classification Fish Evolution Note Set 3 Chapter 3

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

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)

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.

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

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

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.

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

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

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).

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

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.

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.

Coelacanth Figure 4.14: Coelacanth in Indian Ocean.

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

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

Linking Evidence Skulls Parietal foramen Tooth structure 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.

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

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

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

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