5 Major Phyla Deuterostomes l Chordata Vertebrata Gnathostomes

5. Major Phyla Deuterostomes: l. Chordata Vertebrata Gnathostomes - Tetrapods 350 mya Devonian 417 mya

Radiation of the “stem tetrapods” !!! Carboniferous Old friends a fish

5. Major Phyla Deuterostomes: l. Chordata Vertebrata Gnathostomes - Tetrapods Caecilians Salamanders Frogs

5. Major Phyla Deuterostomes: l. Chordata Vertebrata Gnathostomes Tetrapods - Amniotes The amniotic egg was a big advance Resist desiccation - amnion protects the embryo - yolk sac provides nourishment - allantoic sac holds waste produced by embryo Provision embryo allows for colonization of dry habitats

5. Major Phyla Deuterostomes: l. Chordata Vertebrata Gnathostomes Tetrapods - Amniotes SYNAPSID Amniote ancestor ANAPSID (turtles? ) Hylonomus Casineria DIAPSID

5. Major Phyla Deuterostomes: l. Chordata Vertebrata Gnathostomes Tetrapods - Amniotes The Permian Formation of Pangaea dries the landscape; amniotes dominate like the gymnosperms. shelled egg and the seed

5. Major Phyla Deuterostomes: l. Chordata Vertebrata Gnathostomes Tetrapods - Amniotes Dimetrodon – a Pelycosaur The Permian Pelycosaurs The synapsids radiate and dominate Dicynodonts Gorgonopsids Therapsids Cynodonts A cynodont Mammals

5. Major Phyla Deuterostomes: l. Chordata Vertebrata Gnathostomes Tetrapods - Amniotes Mammals - excellent transitional sequences from cynodont ‘reptiles’ - first fossils with all mammalian features (jaw, ear, dentition, fur) date to ~200 mya - Morganucodontids

Radiations of Mammals They diversify during the Mesozoic, but the modern groups radiate and dominate in the Cenozoic

5. Major Phyla Deuterostomes: l. Chordata Vertebrata Gnathostomes Tetrapods - Amniotes Mammals - Monotremes: lay eggs, “sweat” milk

5. Major Phyla Deuterostomes: l. Chordata Vertebrata Gnathostomes Tetrapods - Amniotes Mammals - Monotremes: egg laying, “sweat” milk - Marsupials: live birth to embryo – attaches to nipple to complete development. Mother does not need to abandon the nest/young to feed. Pygmy possum – Australia (opossums in Western Hemisphere)

5. Major Phyla Deuterostomes: l. Chordata Vertebrata Gnathostomes Tetrapods - Amniotes Mammals - Monotremes: egg laying, “sweat” milk - Placentals: Longer internal development allows for precocial behavior (independence on birth); placental allows for direct, energyefficient transfer of nutrients between blood systems of mother and offspring. Each energy transformation is less than 100% efficient Milk production in mammary glands FOOD for OFFSPRING DIGESTION Nutrients in bloodstream of mother Placenta - Marsupials: live birth to embryo – attaches to nipple to complete development. Mother does not need to abandon the nest/young to feed. FOOD Nutrients in bloodstream of offspring

5. Major Phyla Deuterostomes: l. Chordata Vertebrata Gnathostomes Tetrapods - Amniotes Mammals - Monotremes: egg laying, “sweat” milk - Marsupials: live birth to embryo – attaches to nipple to complete development. Mother does not need to abandon the nest/young to feed. - Placentals: Longer internal development allows for precocial behavior (independence on birth); placental allows for more direct and energy-efficient nutrient transfer precocial altricial

5. Major Phyla Deuterostomes: l. Chordata Vertebrata Gnathostomes Tetrapods - Amniotes In the Mesozoic, the synapsids are replaced by the great diapsid radiations of Ichthyosaurs, Pterosaurs, and Dinosaurs Archosaurs: Dinosaurs, Pterosaurs, Crocodilians, Birds Lepidosaurs: Lizards, Snakes, Sphenodonts) Diapsida Ichthyosaurs Younginiformes

5. Major Phyla Deuterostomes: l. Chordata Vertebrata Gnathostomes Tetrapods - Amniotes - Archosaurs Crocodilians Pterosaurs Ornithiscians Dinosaurs Saurischians Sauropods Theropods Carnosaurs Birds

5. Major Phyla Deuterostomes: l. Chordata Vertebrata Gnathostomes Tetrapods - Amniotes Birds: (derived traits) No teeth Feathers and endothermy flight feathers keeled breastbone Clavicles united into wishbone Pneumatic skeleton (houses air sacs from respiratory system) Unidirectional respiration

5. Major Phyla Deuterostomes: l. Chordata Vertebrata Gnathostomes Tetrapods - Amniotes In the Mesozoic, the synapsids are replaced by the great diapsid radiations of Ichthyosaurs, Pterosaurs, and Dinosaurs Archosaurs: Dinosaurs, Pterosaurs, Crocodilians, Birds Lepidosaurs: Lizards, Snakes, Sphenodonts) Diapsida Ichthyosaurs Younginiformes

5. Major Phyla Deuterostomes: l. Chordata Vertebrata Gnathostomes Tetrapods - Amniotes - Lepidosaurs Keuhniosaurs Squamates Scales, moveable quadrate (double hinged jaw), hinged skull Rhynchocephalians (Tuatara)

5. Major Phyla Deuterostomes: l. Chordata Vertebrata Gnathostomes Tetrapods - Amniotes - Lepidosaurs - Squamates