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:
Vertebrate Evolution and Diversity Chapter 34
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.
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.
Pharyngeal gill slits connect pharynx, just posterior to mouth, to outside of animal. Most chordates have muscular tail extending posterior to anus.
Tunicates Sessile marine animals that adhere to rocks, docks, and boats. Invertebrates - urochordates. Chordate characteristics are present as larva. Suspension-feeders.
Lancets Cephalochordates - have chordate characteristics in adult. Suspension-feeders.
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.
Have appendicular skeleton, supporting 2 pairs of appendages (fins, legs, or arms). Can be made of either bone, cartilage, or both.
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.
Lampreys - parasites with cartilage skeletons. Lack backbone - have notochord.
Jawed fish Jawed fish broken into 2 classes (extant). Chondrichthyes (cartilaginous fishes: sharks, rays), Osteichthyes (bony fishes: ray-finned fishes, lobe-finned fishes, lungfishes).
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)
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.
Tetrapods Tetrapods -land animals - walk on all fours - transition from water animals to land animals - amphibians.
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.
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.
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.
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)
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.
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.
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.
Large brains of birds (proportionately larger than reptiles or amphibians) support very complex behavior. Birds - endotherms - metabolism allows them to regulate internal temperature.
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.
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.
Primates - most advanced of eutherians. Opposable thumb characteristic of most advanced primates. Divided into 2 groups: prosimians (lemurs), anthropoids (apes, humans).
New World monkeys - arboreal (live in trees) - tails used for grasping.
Hominoid - great apes and humans collectively. Hominid - group closely related to humans. Human evolution included many adaptations - larger brains, ability to stand upright.