General Biology II- Chapter 34C

Classification of Amphibians and Reptiles

  • Amphibians: Include various classes such as Caecilians, Salamanders, and Frogs.
  • Tetrapods: Vertebrates that have four limbs, a key transition from aquatic to terrestrial life.
  • Reptiles: Classified into different clades and groups, each showcasing unique adaptations.

Major Clades of Reptiles

  • Clade Amniota: Characterized by the development of the amniotic egg, which allows for reproduction in terrestrial environments. Key components include:

    • Amnion: Protects the embryo.
    • Yolk Sac: Provides nutrients.
    • Chorion: Involved in gas exchange.
    • Allantois: Stores excreted material from the embryo.

  • Clade Diapsida: A key group among reptiles characterized by two temporal fenestrae (skull openings) allowing for better jaw movement. Typically ectothermic (cold-blooded).

    • Clade Lepidosauria: Includes tuataras, snakes, and lizards.
    • Clade Archosauria: Comprises turtles, crocodilians, pterosaurs, and dinosaurs, including birds.

Squamates

  • Squamates: Largest group of reptiles, includes around 8,000 species of snakes and lizards.
    • Snakes: Obligate carnivores, lack limbs, have heat-detecting pits, and a loosely articulating jaw.
    • Examples include the Western diamondback rattler, Burmese python, and various sea snakes.
    • Lizards: Include species such as chameleons, green anoles, and komodo dragons.

Turtles and Their Diversity

  • Turtles: Comprising 307 species that include:
    • Loggerhead, Green, Leatherback, and Hawksbill turtles.
    • Florida-specific species such as the Gopher tortoise and Florida cooter.

Crocodilians

  • Crocodilians: 23 species including:
    • Alligators and crocodiles (e.g., American crocodile, Nile crocodile).
    • Diversely adapted for both land and aquatic habitats.

Dinosaurs and Birds

  • Clade Dinosauria:

    • Ornithischian dinosaurs: Herbivorous, non-avian.
    • Saurischian dinosaurs: Include theropods, which led to modern birds.

  • Birds: Approximately 10,000 species characterized by:

    • Endothermic metabolism (warm-blooded).
    • Unique adaptations for flight including feathers, hollow bones, and advanced respiratory systems.

Mammals

  • Mammals: Approximately 5,300 species classified into different clades:

    • Clade Synapsida: Early ancestors of mammals.
    • Key features: hair, mammary glands, and a high metabolic rate.

  • Three major groups:

    • Monotremes: Egg-laying mammals (e.g., platypus, echidna).
    • Marsupials: Characterized by a pouch (e.g., kangaroo, opossum).
    • Eutherians: True placental mammals (e.g., humans, dogs).

Unique Features of Mammals

  • Mammals have specialized adaptations including:
    • Hair for insulation and protection.
    • Mammary glands for feeding young.
    • Advanced kidneys to conserve water, particularly significant in arid environments.