The Vertebrate Genealogy

Topics

Reminders

• Chapter 30, pp 635-666
• Emphasis: class outline
• Study Outline: pp 666-668
• Self Quiz: 668-669

1. Introduction

• coverage, emphasis on pp 635-640
• know all classes and characteristics, pp 640-656
• know aspects of evolution

2. Phylum Chordata

• General
  • very diversified
  • freshwater, marine, terrestrial
  • Amphioxus, sea squirts, vertebrates
• Characteristics of chordates
  • notochord
  • dorsal hollow nerve chord
  • pharynx slits
  • muscular postanal tail
• Classification of Chordates
  • Subphylum Cephalochordata
    • Amphioxus
  • Subphylum Urochordata
    • sea squirts, tunicates
  • Subphylum Vertebrata
    • lampreys, sharks, fish, amphibians, reptiles, birds, and mammals

3. Chordate without Backbones

• Subphylum Cephalochordata (fig. 30.3)
  • Amphioxus or lancelets
  • feeds by a mucous net across pharyngeal slits
  • muscle pattern very obvious
    • segmentation pattern (secondary evolution) comes from somites
• Subphylum Urochordata (fig.30.4)
  • sea squirts or tunicates
  • filter feeders
  • sessile marine animals
  • adult: no notochord, no central nervous
  • system, no head
  • larva: has the four anatomical features
  • metamorphosis

4. The Origin of Vertebrates (fig. 30.5)

• appears in fossil record in Cambrian
• Burgess Shale of British Columbia, Canada
• fossilized cephalochordates
• protovertebrates, probably urochordate,
• but the larval form, not adult
• paedogenesis

5. Vertebrate Characteristics

• Table 30.1
• highly cephalized
• well developed sense organs and brain
• most possess vertebrae (segmentation)
• endoskeleton
• usually paired appendages
• closed circulatory system: heart, arteries and veins
• sexes separate in most vertebrates

Fishes

• Class Agnatha
• Class Placodermi
• Class Chondrichthyes
• Class Osteichthyes

6. Class Agnatha

• jawless vertebrates
• lampreys and hagfishes
• cartilaginous skeleton
• lack paired appendages
• gills
• notochord persist throughout life

7. Class Placodermi

• origin of hinged jaws (fig. 30.7)
• paired appendages

8. Class Chondrichthyes

• sharks, skates and rays
• cartilaginous
• jaws
• gills
• internal fertilization
• eggs or live birth

9. Class Osteichthyes

• bony fishes: tilapia, bass, cod, walleye, catfish
• bony skeleton and jaws
• external fertilization
• gills
• swim bladder

Tetrapods

10. Class Amphibia

• General
  • frogs, toads, salamanders and caecilians
  • first vertebrates on land
    • lobe-finned species and lungs
  • 350,000,000 years
  • only tetrapod during Devonian and early Carboniferous
• Characteristics
  • usually limited to a moist environment, skin permeable to water
  • lungs and skin serve as respiratory structures
  • limbs extend laterally
  • predators
  • metamorphosis, found in some species
    • aquatic larval stage
    • aquatic/terrestrial adult stage
• reproduction
  • in an aquatic environment
  • external fertilization, some exceptions

11. Class Reptilia

• General
  • first reptiles, upper Carboniferous, 300,000,000 yr
  • Age of Reptiles: Mesozoic Era (200,000,000 years)
  • extant: snakes, lizards, turtles, alligators
  • extinct: dinosaurs
  • Cretaceous crisis
• Characteristics
  • terrestrial adaptation
  • scales, help prevent dehydration
  • well-developed lungs and circulatory system
  • limbs extend laterally or ventrally
  • ectodermic or endothermic
• reproduction
  • amniotic eggs: aquatic environment
  • some live births, viviparous
  • internal fertilization
  • copulation
  • courtship behavior

12. Class Aves

• General
  • evolved from dinosaurs in Mesozoic
• Characteristics
  • feathers
  • scales on legs
  • all systems adaptive to flight
  • flightless birds are secondary
  • bones are light and honey combed
  • toothless, but have beak
  • food is chewed in gizzard
  • fat layer for insulation
  • efficient lungs and heart
  • endothermic
• reproduction
  • complexed courtship and behavior
  • internal fertilization
  • care of young, brooding
  • one ovary, one oviduct
  • larger brain than reptiles

13. Class Mammalia

• General
  • evolved from reptiles in Triassic Period (190m)
  • early mammal shrew-like, nocturnal
• Three Groups
  • Monotremes: duck-billed platypus
    • egg layers
  • Marsupials: oppossums, kangaroos
    • early birth as an embryo and development in a pouch
  • Placentals: dogs, cats, elephants, humans
    • joined to the mother by a placenta
• reproduction
  • mammary glands, nursing of young with milk
  • long duration of parental care
• Characteristics
  • hair, did not evolve from scales or feathers
  • diaphragm
  • differentiation of teeth, shearing, grinding or crushing
  • excellent sensory system, many are nocturnal
  • larger brain than other animals
  • very adaptive
    • bats, rats, whales, sheep, cats, monkeys, apes, humans, elephants
• primates
  • opposable thumb
  • brachiation
  • larger brain capacity
  • care of young