Vertebrate Evolution & Diversity

Chapter 34

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Anatomical Features of
Phylum Chordata

•      Notochord

•      Dorsal, hollow nerve cord

•      Pharyngeal slits

•      Muscular, postanal tail

 

Chordates

•      Urochordata - tunicates

•      Cephalochordata - lancelets

•      Vertebrata – vertebrates

 

Characters of the Vertebrates

•      Neural crest

•      Pronounced cephalization

•      Vertebral column

•      Closed circulatory system

 

Superclass Agnatha -
Jawless Vertebrates

•      Class Myxini - Hagfishes

•      Class Cephalaspidomorphi – Lampreys

 

Superclass Gnathostomata -
Vertebrates with Hinged Jaws

•      Class Chondrichthyes - cartilaginous fishes

•      Class Osteichthyes - bony fishes

•      Class Amphibia - amphibians

•      Class Reptilia - reptiles

•      Class Aves - birds

•      Class Mammalia – mammals

 

Class Chondrichthyes -
Cartilaginous fishes

•      Cartilaginous skeleton

•      Respiration through gills

•      Internal fertilization

•      Oviparous, ovoviviparous, vivaparous

•      Lateral line system

•      Includes sharks, skates, rays

 

Class Osteichthyes -
Bony Fishes

•      Bony skeletons and jaws

•      Fertilization external in most species

•      Respiration through gills

•      Many have swim bladder

•      Bony fishes (fresh water and marine)

 

Tetrapods

•      Amphibians

•      Reptiles

•      Birds

•      Mammals

 

Class Amphibia -
Amphibians

•      Tetrapod condition

•      Exhibit metamorphosis

•      Oviparous to viviparous

•      Respiration through skin and/or lungs

•      Includes salamanders, frogs, toads, newts, caecilians

 

Amniotic egg -
Extraembryonic membranes

•      Amnion - protection

•      Allantois - gas exchange, wastes

•      Chorion - gas exchange

•      Yolk sac – nutrients

 

Amniotes

•      Reptiles

•      Birds

•      Mammals

 

Class Reptilia -
Reptiles

•      Tetrapod condition

•      Scaly skin (terrestrial adaptation)

•      Respiration via lungs

•      amniotic eggs or live birth

•      Includes snakes, crocodilians, turtles, lizards

 

Class Aves -
Birds

•      Tetrapod condition

•      Forelimbs modified as wings

•      Respiration through lungs

•      Endothermic

•      Internal fertilization

•      Shelled amniotic eggs

•      Birds

 

Class Mammalia -
Mammals

•      Tetrapod condition

•      Young nourished from mammary gland

•      Hair (or fur)

•      Diaphragm that ventilates lungs

•      Endothermic

•      Amniotic sac

•      Most viviparous

 

Mammals -
3 Major Groups

•      Monotremes - lay eggs - platypus, echidna - found only in Australia and New Guinea

•      Marsupials - pouched mammals - kangaroos, bandicoots, etc. - Australia is center of diversity

•      Eutherian (placental) mammals - young develop within placenta of mother - largest group; worldwide in distribution

 

Mammals -
Order Primates

•      Prosimians - “premonkeys” - lemurs, pottos, tarsiers - Africa and southern Asia

•      Anthropoids - monkeys, apes & humans

 

Study of Vertebrates

•      Reptiles & Amphibians - Herpetology

•      Birds - Ornithology

•      Mammals - Mammalogy