Bio1151 Chapter 34 Vertebrates
  1. Vertebrates possess            , and are a sub-phylum of phylum           .

    Phylum Chordata are bilateral animals that belong to the clade Deuterostomia.

    Vertebrates are a sub-phylum within Chordata that possess a vertebral column (backbone).

    Phylum Chordata are animals that possess four derived traits:

  2. a flexible notochord
  3. a dorsal, hollow nerve cord
  4. pharyngeal slits
  5. a muscular, post-anal tail

      The notochord is a stiff but flexible rod between the digestive tube and the nerve cord.

      In humans, it is reduced to gelatinous disks between the vertebrae.

      The nerve cord is a hollow tube comprising the central nervous system: the brain and a spinal cord enclosed by vertebrae.

      Chordate embryos possess pouches(pharyngeal slits) in the pharynx (region posterior to the mouth). Pharyngeal slits develop into gills in fishes, and structures in the head, ear, and neck in terrestrial vertebrates.

      Chordates have a muscular tail posterior to the anus.

      The tail contains muscles, and provides the propelling force in many aquatic species.

  6. Craniates are chordates that have a       and includes hagfish.

    Craniates have a head with a cranium (skull).

    The cranium is derived from ectodermal cells called the neural crest.

    Hagfish (Myxini) are jawless marine craniates that have a cartilage skeleton, but no vertebrae. They can produce copious amounts of slime, which they clean off by tying themselves in a knot. Slimy hagfish:
  7.              are craniates that have a           , made of vertebrae.

    Vertebrae are made of a series of bones that make up the backbone and enclose the spinal cord.
  8.               are vertebrates that have       that evolved from skeletal supports of the pharyngeal slits.

    The evolution of vertebrate jaws. The skeleton of the jaws and their supports evolved from two pairs of rods skeletal rods located between gill slits near the mouth.
  9.                 include sharks and rays with a skeleton made of            .

    Chondrichthyes have a skeleton made of cartilage. Blacktip reef sharks are fast swimmers with paired pectoral and pelvic fins. Stingrays are bottom-dwellers that crush molluscs and crustaceans. Manta rays cruise in open water and scoop food into their mouth. Spotted ratfish feed on shrimps, molluscs, and sea urchins. Some species have a poisonous spine at the front of their dorsal fin.

      Manta Ray:
  10.               are fish with a       endoskeleton.

    Osteichthyes have a bony endoskeleton. They control buoyancy with a swim bladder, and breathe through gills that are covered by a flap (operculum). A lateral line allows fish such as sardines to sense vibrations in the water and change directions in synchrony. Schooling fish
    •                 are ray-finned fishes.

      Actinopterygii (ray-finned fishes) have fins supported by bony spines ("rays").

      The fins are adapted for maneuvering, defense, and other functions.

    •                are lobe-finned fishes with more muscular pelvic and pectoral fins and include coelacanths and lungfishes.

    Coelacanths live in deep ocean, and were thought to be extinct until discovered in 1938. They form one of only two surviving lineages of aquatic lobe-fins.

    Lungfishes (order Dipnoi) have a modified swim bladder that allows them to breathe air.
  11. Tetrapods are Gnathostomes that have       limbs, and evolved from lobe-finned fish whose fins developed into limbs adapted for terrestrial life.

    Acanthostega from the Devonian period (365 MYA) had limb-like fins but also retained aquatic adaptations such as gills. Tetrapods evolved from similar members of the bony fishes called lobe-finned fishes.

    The origin of tetrapods.

    Tetrapods are terrestrial vertebrates with four legs.

    A great diversity of tetrapods emerged during the Devonian and Carboniferous periods.

  12.           undergo                from aquatic larva into a terrestrial adult.

    Amphibia lead "two ways of life". Fertilization is external, and the eggs require a moist environment. Aquatic larva undergo metamorphosis to develop into a terrestrial adult. Most amphibians have moist skin that complements the lungs in gas exchange
    • There are        orders:          are salamanders,        are frogs and toads, and        are caecilians.

    Class Amphibia. Order Urodela (salamanders) retain their tail as adults. Order Anura (frogs) lack a tail as adults. Order Apoda (caecilians) are legless, mainly burrowing amphibians.
  13. Amniotes are            that have an           egg adapted for terrestrial life.

    Amniotes comprise

  14. Diapsids (most reptiles, including birds),
  15. Synapsids (mammals are sole living members).

    The amniotic egg contains several membranes that allowed animals to live a fully terrestrial life style.
  16. The amnion protects the embryo in a fluid-filled cavity that serves as a cushion.
  17. The allantois holds metabolic wastes produced by the embryo.
  18. The chorion exchanges gases between the embryo and the air.
  19. The yolk sac provides nutrients; other nutrients are stored in the albumen (egg white).
  20. Living reptiles include          ,         ,          ,               , and        .

    Reptiles include:

  21. lizards
  22. snakes
  23. turtles
  24. crocodilians
  25. birds

      There are over 4,000 species of extant lizards, making them the most diverse reptiles, apart from birds. Horned lizard:

      Snakes evolved from lizards. Some snakes such as pythons and boas retain primitive limbs.

      The shell of turtles is made of an upper carapace and lower plastron.

      This species is sold in pet shops, but not native to northern Illinois.

      exhibit temperature-dependent sex determination: high nest temperatures produce male offspring.

      They also show some parental care by guarding the nest and defending their young.

      Emu. This Australian bird has no keel on its sternum and cannot fly. Mallards exhibit strong sexual dimorphism between the sexes. Many birds have specific courtship rituals. Laysan albatross: Barn swallows are perching birds; the toes can lock around a branch or wire.
  26. Mammalia are the only surviving clade of            among the amniotes.

    Class Mammalia contains 20 orders of animals, including humans.

    Mammals possess hair (or fur) and produce milk from mammary glands.

    • Monotremes are the only mammals that lay        .

      Monotremes such as this echidna have hair and produce milk, but lack nipples and lay eggs. The milk is secreted by glands on the belly of the mother, and the baby sucks milk from the fur. Monotremes are only found in Australia.
    • Marsupials complete embryonic development within a maternal pouch called            .

      Marsupials belong to the Chordate class Mammalia that are born early and complete embryonic development within a maternal pouch (marsupium).

      Many marsupials in Australia resemble eutherians elsewhere that occupy similar ecological niches due to convergent evolution.

      The young of marsupials (such as this brushtail possum) are born early in their development. They finish their growth nursing from a nipple in their mother's pouch, or marsupium. Bandicoots have rear-opening pouch to protect the young from dirt as the mother digs. Marsupials are mainly found in Australia, though North America does have one species.
    • Eutherians are            mammals that complete their embryonic development within a         , joined to the mother by the placenta.
  27. Anthropoids are a branch of           and include monkeys and hominoids called       .

    Primates have opposable thumbs adapted for grasping. Anthropoids began diverging from other primates about 50 million years ago.
    The human lineages branched off from our closest relatives about 5 to 7 million years ago.

    New World monkeys such as this spider monkey have a prehensile tail adapted for grasping; their nostrils that open to the sides. Old World monkeys such as this macaque lack a prehensile tail; their nostrils open downward.

    Hominoids (or apes) include:

  28. gibbons
  29. orangutans
  30. gorillas
  31. chimpanzees
  32. bonobos.
  33. Hominin are more closely related to humans than to chimpanzees and originated in          about 6-7 million years ago.


  34. Lucy, a 3.24-million-year-old skeleton, represents the hominin species Australopithecus afarensis.
  35. The Laetoli (Tanzania) footprints, more than 3.5 million years old, showed that early hominin could walk upright.
  36. An artist's reconstruction of what A. afarensis looked like.
  37. The Homo genus slowly became more fully          and evolved a large        .

    The Homo lineage.

  38. Homo habilis
  39. Homo ergaster
  40. Homo erectus
  41. Homo neanderthalensis
  42. Homo sapiens may be the only animals capable of symbolic thought.

    Exercise: Human evolution

      Homo habilis lived about 2.4 to 1.6 million years ago, and made stone tools.

      Its name means "handy man". The brain size was relatively small.

      Homo ergaster was the first fully bipedal and large-brained hominin.

      This 1.7-million-year-old fossil from Kenya belongs to a young male.

      Homo erectus originated in Africa 1.8 million years ago.

      It was the first hominin to leave Africa.

      Homo neanderthalensis lived in Europe and the Near East from 200,000 to 30,000 years ago.

      There may have been limited gene flow between Neanderthals and H. sapiens before the former became extinct.

      The oldest known fossil of Homo sapiens suggests that we first appeared in Africa about 160,000 years ago.

      Art, a human hallmark.

      The engravings on this 77,000-year-old piece of ochre are among the earliest signs of symbolic thought in humans.

      Are birds capable of symbolic thought?

      Alex the talking parrot Betty the crow

    Summary: Characteristics of chordates