Dinosaur Paleobiology Geology 331 Paleontology Dinosaurs are popular with the public Jack Horner, Montana State Univ. Field Work in Montana A dinosaur “drumstick” in its field jacket. Velociraptor was a very active predator Utahraptor waiting to ambush Velociraptors hunted in packs Abundant vascular canals in dinosaur bone support the warm- blooded theory Thin section of dinosaur bone www.bio.fsu.edu/erickson/histological_analysis.php Heart Structure 2 Chambers: 3 Chambers: 4 Chambers: Fish Lizard Birds & Mammals Fossilized heart in an ornithopod. CAT scan shows it has 4 chambers. RV LV Evidence for Dinosaur Endothermy • Erect and bipedal posture • Bone histology – abundant vascular canals • Head above the heart required high blood pressure and, thus, a four-chambered heart: 2 ventricles and 2 atriums. • Fossilized four-chambered heart? • Birds are descendants of theropods • High latitude occurrences – how did they survive months of darkness? • Predator:prey biomass ratio of 1:20 from the Late Cretaceous of Alberta similar to modern endotherms. Modern ectotherms are 1:3. Dinosaur classification Hip Bones: The Primary Homology Difference Between the Two Major Dinosaur Groups Saurischian Ornithischian Saurischian hip structure (theropod) Ischium Pubis Saurischian hip structure (sauropod) Ischium Pubis Ornithiscian hip structure (stegosaur) Ischium Pubis Excavating bones at Dinosaur National Monument in Utah A dinosaur mummy from Mongolia Coelophysis, a late Triassic bipedal ancestor Tyrannosaurus rex, the Cretaceous theropod everyone loves to fear Modern view of a T.rex Peter Larson with Sue Hendrickson, founder of the T. rex named “Sue” I found it first! Sue on display in Chicago T. rex, Stan Black Hills Institute Tyrannosaurs, Carnegie Museum, 2009 Mechanical model of T. rex shatters a large bone Peter Larson with a Nanotyrannosaurus skull at his lab at the Black Hills Institute, SD More scenes at the Black Hills Institute, SD Compsognathus, a chicken-sized theropod. It’s skeleton is similar to Archaeopteryx. The “compies” of Jurassic Park. Archaeopteryx, the first bird. Its skeleton is nearly identical to Compsognathus. A feathered(?) Velociraptor Apatosaurus or Brontosaurus, the classic sauropod Apatosaurus out for a stroll A modern view of sauropods Sauropod trackways showing no evidence of tail dragging. Diplodocus - a gracile sauropod Sauropods, Carnegie Museum, 2008 Sauropods, Carnegie Museum, 2008 Sauropods, Carnegie Museum, 2008 Sauropods, Carnegie Museum, 2008 Sauropods, Carnegie Museum, 2008 Looks like your diet is working! Sauropods eating a coniferous forest The massive digestive system of a sauropod, note the large gizzard Inside of sauropod gizzard, note the gastroliths for grinding food Sauropod gastroliths Sauropods protecting their young, South America Theropod tracks in Utah Iguanodon, an ornithopod A Cretaceous ornithopod Crested hadrosaur or “duck-bill” Duck-billed hadrosaur Hadrosaur barbershop wall chart Skull of a pachycephalosaur Head butting by pachycephalosaurs Stegosaurus Stegosaurus Ankylosaurus Protoceratops from Mongolia Triceratops at the Smithsonian Institution .