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Vertebrates. Which of these is most closely related to you?. Which of these is most closely related to you?. Echinoderms and Chordates are the only two phyla of deuterostomes. Vertebrates. Chordata fish, amphibians, reptiles, birds, mammals. Deuterostome coelomates
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Echinoderms and Chordates are the only two phyla of deuterostomes. Vertebrates
Chordata fish, amphibians, reptiles, birds, mammals Deuterostome coelomates Notochord serves as axis of body Dorsal, hollow nerve cord Tails. Human coccyx is vestigial tail. Birds & mammals = homeotherms (constant body temperature) All others are poikilotherms (cold-blooded) though some reptiles are endothermic.
Mammalsclass Nurse their young with milk Have hair or fur made of keratin Homeotherms Placental = develops in womb Marsupial = born early, develops in pouch Monotreme = egg-laying (duck-billed platypus and spiny anteater).
Primatesorder Hands with opposable thumbs Claws have become nails Eyes are in front and close together for binocular vision Nurture their young for a long time.
A flexible rod between the nerve cord and the digestive tube All chordates have this as embryos Most develop later into complex, jointed skeleton. Chordate Characteristics Notochord
Develops from a plate of ectoderm that rolls into a tube Unique to chordates. (Other phyla have solid, ventral nerve cords) Develops into central nervous system, spinal cord, and brain. Chordate Characteristics Dorsal, hollow nerve cord
Just posterior to the mouth Used for suspension feeding and gas exchange (gills) In land animals, they develop into parts of the ear. Chordate Characteristics Pharyngeal slits or clefts
Lost during embryonic development in many species Provides propulsion for many aquatic species. Chordate Characteristics Muscular, post-anal tail
Classes of Chordates Tunicates
Classes of Chordates Tunicates
Classes of Chordates Tunicates
Classes of Chordates Tunicates
Classes of Chordates Lancelets
Classes of Chordates Lancelets
Classes of Chordates Hagfish • Craniate (has brain and skull) • No jaws • No vertebrae
Classes of Chordates Hagfish
Classes of Chordates Hagfish
Classes of Chordates Hagfish
Classes of Chordates Lamprey • Vertebrate (has backbone) • Still no jaws
Classes of Chordates Lamprey
Classes of Chordates Lamprey
Classes of Chordates Lamprey
Classes of Chordates Sharks and Rays • Gnathostomes (“jaw-mouths”) • Bones have some mineralization but are still mostly cartilage • Acute senses (lateral line, nostrils, black-and-white vision) • Oviparous, ovoviviparous, or viviparous.
Classes of Chordates Sharks and Rays
Classes of Chordates Sharks and Rays
Classes of Chordates Sharks and Rays
Classes of Chordates Ray-Finned Fishes
Classes of Chordates Lobe-Finned Fishes
Classes of Chordates Lungfishes
Classes of Tetrapods Amphibians Urodela (“tailed ones”) Salamanders Anura (“tailless ones”) Frogs and toads Apoda (“legless ones”) Caecilians
Classes of Tetrapods • Amphibians • Adaptations: • Camouflage • Poison • Metamorphosis / paedomorphosis • Complex social behavior • Eggs lack shells, dehydrate quickly • Gas exchange through moist skin
Amniotes • Amniotic egg may be laid on land. • Contains extra-embryonic membrane • May be calcified (birds) or leathery (reptiles) or may implant in the uterus (mammals)
Phylogeny of Amniotes Synapsidia Anapsidia Ancestral amniote Diapsidia
Phylogeny of Amniotes Mammals Turtles Lizards & Snakes Crocodiles Dinosaurs Birds Synapsidia Anapsidia Ancestral amniote Diapsidia
Phylogeny of Amniotes Mammals Turtles Lizards & Snakes Crocodiles Dinosaurs Birds Synapsidia Anapsidia Ancestral amniote Diapsidia
Reptiles • Adaptations: • Keratinized skin • Lungs • Leathery shells on eggs • Ectotherms.
Birds began as feathered reptiles • Adaptations: • Feathers • Honeycombed bones • Missing some organs • Gizzard instead of teeth • Endothermic • Four-chambered heart • Good vision • Relatively large brains.
Mammals diversified in the wake of the Cretaceous extinctions • Adaptations: • Mammary glands • Hair • Four-chambered heart • Endothermic • Placenta / live birth • Large brains • Differentiated teeth.
Primates and Human Evolution • Adaptations: • Brain size • Jaw shape • Bipedal posture • Size difference between sexes • Long-term pair bonding • Long-term infant dependency.
Multiregional Hypothesis interbreeding 1-2 million years ago African European Asian Austalasian Homo erectus In Africa
Replacement Hypothesis 100,000 years ago 1-2 million years ago African European Asian Austalasian Homo erectus In Africa