Vertebrate Characteristics

Kingdom Animalia; Phylum Chordata; Subphylum Vertebrata

Chordata Characteristics

Dorsal hollow nerve cordNotochord (“back cord”)Pharyngeal gill slits/arches+/- postanal tail

Subphylum Vertebrata

500 million years ago; Ordovician PeriodAbout 50,000 species known

Geologic PeriodsPALEOZOIC ERA

Cambrian Period 600 mya– appearance of all major invertebrate phyla 

Ordovician Period 500– appearance of vertebrates (ostracoderms)

Silurian Period 440– archaic fishes 

-Devonian Period 410age of fishes; first amphibians

-Carboniferous Period 360amphibians dominant; first reptiles

-Permian Period 290 primitive reptiles, decline of early

amphibians

MESOZOIC ERA(age of reptiles; 185 million yrs. duration)-Triassic Period 245

first dinosaurs, turtles, mammals

-Jurassic Period 210reptiles dominant; first birds; arc. mammals

-Cretaceous Period 145 extinction large reptiles

CENOZOIC ERA

(age of mammals; 65 million yrs. duration)

Key Points

From the Geologic Periods page, name 3 of the most important dates & events

Origins of Vertebrates

Prochordate, such as AmphioxusCompare to Ammocoete larvae

Amphioxus

Larval agnathan - Ammocoetes

Vertebrate Characteristics

SUPERCLASS AGNATHA

Ostracoderms

SUPERCLASS AGNATHA

Cyclostomes

AgnathaAgnatha

Lampreys & Hagfishes or Slime Eels

SUPERCLASS GNATHOSTOMATA

Class Acanthodii

Class Placodermi

Class Chondrichthyes

Cartilaginous fish

(Chondrichthyes)Subclass Elasmobranchii

Class ChondrichthyesSubclass Elasmobranchii

Class ChondrichthyesSubclass Holocephali

Bony Fish

OsteichthyesGreatest number of species of vertebrates

Class Actinopterygii

Ray-finned fishOperculumBony skeletonTerminal mouthSwim bladder in most

Subclass Chondrostei - paddlefish

Subclass Chondrostei - sturgeon

Subclass NeopterygiiOrder Holostei (gar)

Subclass Neopterygiiorder Holostei - bowfin

Subclass Neopterygiidivision Teleostei

“perfect” bone95% of all fishModern cycloid or ctenoid scales

Class Sarcopterygii

Fleshy finned fish

Class SarcopterygiiSuperorder Dipnoi

Class SarcopterygiiSuperorder Crossopterygii

Latimeria = Coelocanth

Transition from water to land

Class Amphibia

Both lifeFewest numbers of speciesTerrestrial life changesMore oxygen in atmosphere than waterAir less dense than water for body supportMore temperature fluctuations

Class AmphibiaSubclass Labyrinthodontia

OLDEST TETRAPOD, about 350 myaCrossopterygian features such as dermal

scales, ray-fin tail, skull and sensory structures fish-like

GAVE RISE TO REPTILES

Class AmphibiaSubclass Lissamphibia

Smooth amphibiansMonophyletic or Diphyletic evolutionSkin with glands and keratinNo dermal scalesDouble circulatory systemEctothermicNeed water for reproduction

Subclass Lissamphibia

Order ProanuraOrder Anura

Subclass LissamphibiaOrder Urodela

Subclass LissamphibiaOrder Apoda

Class Reptilia

CreepsOrigin in mid-Carboniferous periodOrigin from labyrinthodontsAmniotesKeratinized skin with scalesStronger skeleton

Class ReptiliaSubclass AnapsidaExtinct stem reptiles

Class ReptiliaSubclass Anapsida

Class ReptiliaSubclass Lepidosauria

Class ReptiliaSubclass Archosauria

Class ReptiliaSubclass Euryapsida

Class ReptiliaSubclass Synapsida

Therapsids; ANCESTOR OF MAMMALS

Class Aves

Originated from bipedal dinosaursArchaeopteryx in Jurassic PeriodFeathersNo teeth in modern birdsEndothermicFour chambered heartComplex behavior/social organization

Class AvesSubclass Archaeornithes

Class AvesSubclass Neornithes

Class Mammalia

“breast”Originated from TherapsidsHairMammary glandsFour chambered heartDiaphragmDentary is sole lower jaw bone

Class MammaliaSubclass Prototheria

Class MammaliaSubclass Theria

Breast or PLACENTA or hair

Subclass TheriaInfraclass Metatheria

Subclass TheriaInfraclass Eutheria

Key Point: Classify Vertebrates

Gnathostome, Agnathostome

Key Point: Classify Vertebrates

Amniote, Anamniote

Key Point: Classify Vertebrates

Homeotherm/EndothermPoikilotherm/Ectotherm

Key Point: Classify Vertebrates

Fish, Tetrapod