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CH34Origin and Evolution of Vertebrates - General Biology

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  • Phylum Chordata key characteristics

    Four key traits: notochord, dorsal hollow nerve cord, pharyngeal slits or clefts, and muscular post-anal tail.

  • Difference between chordates and vertebrates

    All vertebrates are chordates with vertebrae enclosing the spinal cord; not all chordates have vertebrae.

  • Gnathostomes definition

    Vertebrates with jaws, including sharks, ray-finned fishes, reptiles, birds, and mammals.

  • Derived characters of gnathostomes

    Jaws with teeth, paired fins, enlarged forebrain, and line system for detecting vibrations.

  • Osteichthyes characteristics

    Bony fishes with endoskeletons made of bone with calcium phosphate.

  • Lobe-finned fishes (Sarcopterygii)

    Fishes with fleshy, lobed fins containing rod-shaped bones surrounded by muscle; ancestors of tetrapods.

  • Significance of Tiktaalik

    Fossil 'fishapod' showing transitional features between fish and tetrapods.

  • Derived traits of tetrapods

    Four limbs with digits, neck for head movement, fused pelvic girdle, absence of gills, and ears .

  • Amniotic egg importance

    Egg with protective membranes allowing reproduction on land, key adaptation of amniotes (reptiles, birds, mammals).

  • Mammalian characteristics

    Hair, mammary glands producing milk, high metabolic rate, larger brain, parental care, and differentiated teeth.