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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