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Vertebrate Evolution and Diversity Chapter 34. Vertebrates belong to phylum Chordata. Includes 3 subphyla, vertebrates and 2 phyla of invertebrates, urochordates.

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Presentation on theme: "Vertebrate Evolution and Diversity Chapter 34. Vertebrates belong to phylum Chordata. Includes 3 subphyla, vertebrates and 2 phyla of invertebrates, urochordates."— Presentation transcript:

1 Vertebrate Evolution and Diversity Chapter 34

2 Vertebrates belong to phylum Chordata. Includes 3 subphyla, vertebrates and 2 phyla of invertebrates, urochordates and cephalochordates. 4 characteristics: notochord; dorsal, hollow nerve cord; pharyngeal slits; and muscular, postanal tail.


4 Notochord, present in all chordate embryos - flexible rod between digestive tube and nerve cord. Dorsal, hollow nerve cord develops in vertebrate embryo from plate of ectoderm that rolls into tube dorsal to notochord - can develop into spinal cord.


6 Pharyngeal gill slits connect pharynx, just posterior to mouth, to outside of animal. Most chordates have muscular tail extending posterior to anus.


8 Tunicates Sessile marine animals that adhere to rocks, docks, and boats. Invertebrates - urochordates. Chordate characteristics are present as larva. Suspension-feeders.




12 Lancets Cephalochordates - have chordate characteristics in adult. Suspension-feeders.


14 Lancet

15 Vertebrates Neural crest, pronounced cephalization, vertebral column, closed circulatory system - subphylum Vertebrata. Neural crests start of formation of cranium; cephalization - collection of nervous tissue that forms brain.


17 Have appendicular skeleton, supporting 2 pairs of appendages (fins, legs, or arms). Can be made of either bone, cartilage, or both.


19 Jawless vertebrate 2 classes of jawless vertebrates still living: Class Myxini (hagfish) and Class Cephalaspidomorphi (lampreys). Hagfish - skeletons made of cartilage making them flexible, but no backbone.

20 Hagfish

21 Lampreys - parasites with cartilage skeletons. Lack backbone - have notochord.


23 Jawed fish Jawed fish broken into 2 classes (extant). Chondrichthyes (cartilaginous fishes: sharks, rays), Osteichthyes (bony fishes: ray-finned fishes, lobe-finned fishes, lungfishes).


25 Chondrichthyes - skeleton made of cartilage. Cartilaginous skeleton usually replaced by bone; chondrichthyes - process prevented. Fertilize internally; some lay eggs (oviparous), few give birth to live young (viviparous)


27 Osteichthyes - bony fish - endoskeleton made of bone. Bony fish have swim bladder not found in cartilaginous fish - helps control buoyancy of fish. Bony fish actually broken down into 3 groups: ray-finned fishes, lobe- finned fishes, lungfishes.

28 Ray-finned fishes

29 Lobe-finned fish

30 Lungfish

31 Tetrapods Tetrapods -land animals - walk on all fours - transition from water animals to land animals - amphibians.


33 Class Amphibia - amphibians - salamanders, frogs, caecilians (legless animals that burrow) Fertilization external - lay eggs. Most amphibians rely heavily on moist skin to carry out gas exchange with environment - still tied to water. Some adult frogs have lungs.

34 Caecilian



37 Amniotes Mammals, birds, reptiles, including turtles, lizards, snakes, crocodiles. Transition to land - adaptations were needed: amniotic egg, waterproof skin, increasing use of rib cage to ventilate lungs.


39 Amniotic eggs of most amniotes have shell that retains water - can be laid in dry place. Inside shell of amniotic egg - several extraembryonic membranes that function in gas exchange, waste storage, and transfer of stored nutrients to embryo.


41 Reptiles Class Reptilia divided into 4 orders. Reptiles - several adaptations for terrestrial life not found in amphibians - leathery skin to prevent dehydration, lungs. Fertilization internal, eggs laid (amniotic eggs)


43 Reptiles - ectotherms - cannot maintain own internal temperature (cold-blooded). Turtles return to water to lay eggs; have not evolved since 1 st appearance. Lizards - most numerous reptiles.



46 Snakes - limbless reptiles - still have pelvic bones - evidence that they evolved from reptiles with legs. Crocodiles and alligators - largest living reptiles. Breathe through their nostrils that are pointed upward out of water.



49 Birds Birds - class Aves - broken down into 28 orders (few flightless birds) Birds evolved to have hollow bones to allow for flight and feathers. Modern birds - toothless - grind food in muscular gizzard near stomach.


51 Large brains of birds (proportionately larger than reptiles or amphibians) support very complex behavior. Birds - endotherms - metabolism allows them to regulate internal temperature.


53 Mammals Mammals - class Mammalia - identified by mammary glands. Most mammals give birth to live young after internal fertilization. Nutrition done via placenta. Most mammals capable of learning due to larger brains.


55 Monotremes - duck-billed platypus and echindas - lay eggs that have yolks to support embryo. Marsupials - born early in development crawl into pouch in mother to complete development. Eutherians - placental mammals.


57 Echinda


59 Opposum


61 Primates - most advanced of eutherians. Opposable thumb characteristic of most advanced primates. Divided into 2 groups: prosimians (lemurs), anthropoids (apes, humans).



64 New World monkeys - arboreal (live in trees) - tails used for grasping.


66 Hominoid - great apes and humans collectively. Hominid - group closely related to humans. Human evolution included many adaptations - larger brains, ability to stand upright.



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