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Kingdom Animalia Part III - Chordate Animals (including the Vertebrates)

Chordate characteristics

(somites)

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SP: Cephalochordata = lancelets

tentacles

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SP: Urochordata = tunicates, sea squirts, salps, ascidians

Craniate features

neural crest tissue

developmental genes now make a brain

Early chordate & craniate animals

Haikouella Myllokunmingia early chordate early craniate

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Vertebrates: cyclostomes (jawless)

Cl: Myxini = hagfishes

Vertebrates: cyclostomes (jawless)

Cl: Petromyzontida = lampreys

Early jawless vertebrates

conodonts

(armored)

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Gnathostomes = jawed mouths

Hypothesis: jaw evolution (remaining gill slits become major sites of gas exchange)

Mouth!

Clasper!

Spleen!Kidney!Stomach!Testis! Gill slits!

Pharynx!Pericardial!cavity!

Heart!Liver!

Pancreas!Intestine!Cloaca!Pelvic!fin!(a)!

Cl: Chondrichthyes = cartilaginous fish

Fig. 30.13a!

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Clade Osteichthyes

Cl: Actinopterygii = ray-fin fishes

Garibaldi (CA state marine fish)

Cl: Actinistia = coelocanths

Cl: Dipnoi = lungfishes

Clade Osteichthyes

Cl: Sarcopterygii (lobed fin fishes)

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Early Tetrapods (many of these added in the last 20 years)

tetrapod

fish “fishapod”

Clade Osteichthyes

Cl: Amphibia

Cl: Anura = frogs & toads

Cl: Apoda = caecilians

Cl: Urodela = newts & salamanders

Clade Osteichthyes

Cl: Amniotes

new invention: amniotic egg with extraembryonic membranes

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(therapsids)

Clade Osteichthyes

Cl: Amniotes

Alternate hypothesis about turtles (closer to other extant reptiles)

Cl: Reptilia

tuatara

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Cl: Reptilia

Birds

Birds: adaptations for flight

Hollow bones

Feathers

Cl: Mammals

Cl: Monotremes = egg-layers

spiny echidna

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Cl: Mammals

Marsupials = pouched mammals

Convergent evolution

Cl: Mammals

Eutherians = placental mammals