December 4, 2009 BReading Ch. 14 BFinal Exam date: TU, Dec. 15 Material covered: Ch. 13, 14, 15, 16 + movie

Marine Vertebrates BBony fishes Primitive sturgeons dominant early Teleosts evolved  mobile jaws, swim bladders –Ex: Xiphactinus BSharks (cartilagenous) Megaladon

Marine Vertebrates BReptiles Nothosaurs and placodonts  Plesiosaurs Ichthyosaurs Mosasaurs Ichthyosaur Plesiosaur Nothosaur Mosasaur

Triassic Mass Extinction (#4) BWiped out ~30% of genera Mostly archosaurs BCause?

Cycad Mesozoic Land Plants BGymnosperms (non-flowering) Cycads  Look like palm trees Ginkgos  Ginkgo biloba survived Conifers Ginkgo Conifers

Mesozoic Land Plants BEvolution of angiosperms (flowering) Flowers help pollination  Double fertilization Faster recovery and growth Fertilization of same species guaranteed  Coevolution with insects  Faster evolution

Mesozoic Land Reptiles BTwo major reptile groups: Lepidosaurs  Ancestors of snakes, lizards Archosaurs  Ancestors of crocs, birds Early archosaur

Age of the Dinosaurs BDino distinctions: Upright posture Ankle joint BTwo major groups: Saurischia group  Lizard-like pelvis Ornithischia group  Bird-like pelvis

Saurischians (lizard-hipped) BSauropods Giant herbivores  Brachiosaurus  Apatosaurus (“Brontosaurus”) BTheropods Carnivores  Tyrannosaurus  Caudipteryx Ancestors of birds

Dino-to-Bird BTransitional fossils Archaeopteryx Limusaurus Archaeopteryx Limusaurus

Ornithischians (bird-hipped) BArmored Stegosaurus Ankylosaurus BDuck billed Hadrosaurus BRimmed head Triceratops Hadrosaurus Ankylosaurus

Flying Reptiles BPterosaurs (flying reptiles) Pterodactyls  Likely rode on updrafts due to size Jeholopterus

Evolution of Mammals BEvolved from synapsids (mammal-like reptiles) BSkeletal distinctions: Middle ear--3 bones Lower jaw--1bone Teeth were differentiated Palate Repenomamus

Evolution of Mammals BEgg layers Monotremes (Platypus) BLive birth Marsupials (pouched)  Premature births  Safer for mom Placentals  Birth when ready  Mom at risk

K/T Extinction B3rd largest Wiped out ~1/2 life BPuzzling evidence: Marine environment  Total loss of ammonites & reptiles (both in decline)  Tropical groups hit hard –Water cooling and regressing Land environment  Decline of angiosperms  Dinosaurs in decline  Not affected –Mammals--placentals became dominant –Turtles, snakes, lizards

Extinction Hypotheses BImpact hypothesis Based on iridium anomaly Chicxulub crater Global cooling, acid rain, fires BVolcanic hypothesis Gigantic lava floods in India, Brazil Ash and CO 2 production BRegression Altered habitats, climate