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Mesozoic Era

Mesozoic Era. Life. Mesozoic Life. Known as “Age of Reptiles”. Mammals and angiosperms evolve. Marine Invertebrates Plankton. 1 st appeared (Jur). Coccolithophores. Abundant (K). Continue today. Diatoms (SiO 2 ). 1 st evolved (K). Cold H 2 O. Dinoflagellates. Warm H 2 O.

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Mesozoic Era

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  1. Mesozoic Era Life

  2. Mesozoic Life • Known as “Age of Reptiles” • Mammals and angiosperms evolve

  3. Marine InvertebratesPlankton • 1st appeared (Jur) • Coccolithophores • Abundant (K) • Continue today • Diatoms (SiO2) • 1st evolved (K) • Cold H2O • Dinoflagellates • Warm H2O • Foraminifera • Exploded • Most plankton extinct (end K)

  4. Marine InvertebratesCorals & Echinoderms • Corals & Echinoderms proliferated Echinoderm Scleractinians

  5. MollusksBrachiopods & Gastropods • Significant invertebrate fauna • Brachiopods • Never fully recovered from Permian extinction • Minor invertebrate • Gastropods • Largest, most varied class • Marine, fresh H2O, terrestrial • Herbivore & carnivore

  6. MollusksBivalves • Burrowing organism • Escaped predators • i.e., oysters, clams • Rudists significant • Formed large tropical reefs • Excellent guide fossils

  7. MollusksCephalopods Cephalopod Nautilus • Important invertebrate group • Ammonites • Complex sutures • Abundant (Jr & K), extinct (end K) • Nautiloids and belemnoids survived

  8. Mesozoic LifeFishes and Amphibians • Cartilaginous fish • ↑ abundance • Amphibians • Frogs and salamanders appear • Greatest diversity (Permian)

  9. Mesozoic LifePlants • Primary producers – base of food chain • Gymnosperms • Gingkos • Conifers • Cycads Modern cycads • Gymnosperms replaced by angiosperms Gymnosperm Angiosperm

  10. PlantsAngiosperms • Factors to success: • Adapted to nearly every terrestrial habitat • Method of reproduction • Evolution of flowers • Pollinators • Evolution of enclosed seed • Seeds dispersed by wind, fruit, burr

  11. Mesozoic LifeReptiles • Diversification began during Penn • Evolution of captorhinomorphs • Thecodontian (L. Per-Tri) • 1st to lay amniote egg • All other reptiles evolved • Small, agile reptiles with long tails, short limbs • Teeth set in sockets • i.e. crocs, dinos, & mammal-like reptiles • Quadrupedal, ran bipedal • Herbivores & carnivores • Dinosaur ancestors

  12. Warm-Blooded Dinosaurs • Animals whose body temp varies in response to outside temp • Ectotherm – “cold-blooded” • All reptiles ectothermic • Endotherm – “warm-blooded” • Capable of maintaining a constant body temp regardless of outside temp • Mammals & birds endothermic • Dinosaurs believed to be endothermic

  13. Warm-Blooded Dinosaurs • Dino bones numerous passageways = blood flow • Endotherm requirements • Crocs, turtles have similar bone structure = ectotherm • High metabolic rates  need to eat more • Dinosaurs  3.5% prey pop’n • Similar to present-day mammals • Complex nervous system  large brain • Many dinos have small brains • Small carnivores = large brain • Active flight requires endothermy • Pterosaurs = hair-like feathers Triceratops brain cavity

  14. Mesozoic LifeDinosaurs Relationships • Two independent orders evolved 1. Saurischia “lizard-hipped” • Theropod & Sauropod 2. Ornithischia “bird-hipped”

  15. DinosaursSaurischia Theropod • Bipedal locomotion • Theropods – “Carnivores” • Various sizes • 60 cm to 15 m • 2 kg to 8 tons • Tyrannosaurus (largest terrestrial carnivore) • Deinonychus – “terrible claw”

  16. DinosaursSaurischia Sauropod • Sauropods – “Herbivores” • Quadruped locomotion • Largest land animals to ever exist • 20 to 35 m in length • 10 to 55 tons Camasaurus “Brontosaur” Brachiosaurus Diplodocus

  17. Mesozoic LifeDinosaurs Relationships • Two independent orders evolved 1. Saurischia • Theropod & Sauropod 2. Ornithischia

  18. DinosaursOrnithischia 1. Duck-billed dinos (K) • Colonial nesting, cared for young, herbivores, bipedal 5 groups 2. Pachycephalosaurs • Dome-shaped skull, bipedal, butting 3. Ankylosaurs • Armored, quadrupeds, tail w/ club-like growth 4. Stegosaurs • Quadruped, herbivore with spike on tail 5. Certopsian • Triceratops, quadrupedal herbivores

  19. Mesozoic LifeWinged Dinosaurs • Pterosaurs • 1st flying vertebrates • Flight adaptations • Winged membrane supported by elongated finger • Pteranodon (K) • Pterosaur • Could actively fly

  20. Mesozoic LifeBirds • Few Meso birds • Archaeopteryx • Jur strata, Germany • Protoavis (Tri) • Crow sized • Hollow bones

  21. Mesozoic LifeEarly Mammals • 1st mammals (Tri) • Small, rodent-like mammals • Evolved from Therapsids • Mammal-like reptiles • Cynodonts • Most abundant mammal-like reptile

  22. Early MammalsCynodonts • Egg-laying • i.e. today’s platypus & string anteater • Monotremes • Eupantotheres • Marsupials – pouched (E. K) • Placental mammals • All living mammals related to this branch

  23. Mesozoic LifeFrom Reptile to Mammal • Middle ear • Skull • Lower jaw • Teeth • Used skeletal structure to classify fossils • Mammal’s middle ear attached to dentary • Reptiles = 1 ear bone; mammals = 3 • Reptile = several jaw bones; mammals = 1 • Teeth = distinct types

  24. Reptile vs. MammalComparison

  25. Mesozoic Era Mass Extinction • Impact Theory • Huge asteroid or comet • Cloud of dust into atmosphere • Reduced sunlight • Plants die first • Herbivores followed • Then, carnivores starved

  26. Mass ExtinctionEvidence • Large impact basin • Iridium-rich clay layers • Rare crustal rock • More in meterorites • Clay layers, New Mexico

  27. Mass ExtinctionProblems • Selective extinction • Dinosaurs completely extinct • Corals, clams, snails – some extinction • Tropical plants, crocodiles, mammals, turtles, snakes, & birds unaffected • Why weren’t all organisms affected equally?

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