VERTEBRATE LIFE



This section gives a brief overview of the classification of the vertebrates.

For more information the following sites are highly recommended:



PHYLUM CHORDATA
        Subphylum CRANIATA
                Infraphylum MYXINOIDEA
                Infraphylum VERTEBRATA
                        Order PETROMYZONTIFORMES
                        GNATHOSTOMATA
                                Class CHONDRICHTHYES
                                Class OSTEICHTHYES
                                        Subclass ACTINOPTERYGII
                                        Subclass SARCOPTERYGII
                                                Order ACTINISTIA
                                                Order DIPNOI
                                                Division RHIPIDISTIA
                                                       Eusthenopteron, Panderichthys, etc.
                                                        EOTETRAPODA
                                                                Ichthyostega and other primitive "amphibians"
                                                                TETRAPODA
                                                                        Order AMPHIBIA
                                                                        AMNIOTA
                                                                                SYNAPSIDA
                                                                                        Class MAMMALIA
                                                                                Class REPTILIA
                                                                                         Testudines
                                                                                         Sauria (lizards, snakes, crocodilians, dinosaurs, and birds)
 


Phylum CHORDATA

Taxa

Chordate characteristics

  1. gill slits in the pharynx
  2. tubular dorsal nerve chord
  3. notochord
  4. endostyle or thymus
  5. postanal tail
  6. tadpole larva

Subphylum CRANIATA

Taxa

Craniate characteristics

  1. distinct head and brain
  2. specialized [paired] sense organs
  3. one or more semicircular canals
  4. gills (for respiration) in pharyngeal slits
  5. W-shaped myotomes

Infraphylum MYXINOIDEA

Infraphylum VERTEBRATA

Taxa

Vertebrate Characteristics

  1. 2 or 3 pairs of semicircular canals
  2. mesonephric kidneys
  3. bone
  4. neural arches


Order PETROMYZONTIFORMES (upper Mississippian, middle Pennsylvanian, Recent)


GNATHOSTOMATA

Learn  more about gnathostomes (vertebrates with jaws) from the Tree of Life

Characteristics

  1. internal jaws (palatoquadrate, Meckel's cartilage) are present.
  2. paired appendages (paired pectoral and pelvic fins supported by an internal skeleton
  3. three semicircular canals

Taxa


CLASS CHONDRICHTHYES (?early Silurian, early Devonian to Recent) Learn  more about cartilaginous fish from the UCMP.

Characteristics

  1. skeleton is composed of cartilage, which may be prismatically calcified
  2. placoid scales
  3. claspers present in males for internal fertilization

Taxa


CLASS OSTEICHTHYES (late Silurian to Recent)

Taxa

Characteristics

  1. internal skeleton ossified (i.e., bony)
  2. swim bladder or lung present


SUBCLASS ACTINOPTERYGII [middle Devonian to Recent]

Learn  more about ray-finned fish from the UCMP or from the Tree of Life.

Taxa

Characteristics

SUBCLASS SARCOPTERYGII

Learn  more about lobe-finned fish from the UCMP or from the Tree of Life.

Characteristics

  1. paired fins that are fleshy, with muscular lobes at base and with only a single element articulating with girdles)
  2. forearm with a single proximal element (humerus), followed by the homologs of the radius and ulna.
  3. paired external nostrils

Taxa

 

ORDER ACTINISTIA (Middle Devonian to Recent)

Taxa

Characteristics

  1. internal nares absent
  2. numerous paired snout bones
  3. caudal fin tri-lobed


SUBCLASS CHOANATA

Characteristics

  1. external nostrils connected by a continuous passage to the internal nares (choana)

Taxa

Comment

 

ORDER DIPNOI (Early Devonian to Recent)

Taxa

Characteristics

  1. large tooth plates on palate, no marginal teeth
  2. anterior of skull roof a mosaic of small bones tightly interconnected


DIVISION RHIPIDISTIA (Devonian to Permian)

Characteristics

  1. skull roof bones homologous with skull and limbs of tetrapods
  2. labyrinthodont teeth typically present

Taxa


Osteolepimorpha
 

DIVISION TETRAPODA

Taxa

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