Paleontologists and their achievements R Owens named Dinosauria O C Marsh and E D Cope rivalry over fossils J Ostrom Dinosaur Renaissance Buckland and Mantel Megalosaurus Iguanodon Hylaeosaurus Steno Hutton and Smith Developed principles of stratigraphy Major changes in our understanding of dinosaurs since the early 19th Century originally thought dinosaurs were only big going back and forth between if they were cold or warm blooded we now know they aren t extinct Dinosaurs the concestor of Iguanodon and Megalosaurus and all of its descendants fearfully great lizards Rocks Metamorphic o o o Igneous o o Sedimentary Sedimentary rocks Formed by recrystallization of previous existing rocks due to intense head and or pressure Rocks are baked and or squashed but not melted or they would become igneous Formed by the cooling of molten material Cooled on the surface volcanic or while still underground plutonic Formed by accumulation of bits of previously existing rock and or organic matter Bits of previous rock and or organic matter are called sediment o Naturally creates horizontal beds called strata Biogenic sedimentary rocks sediment made of solid bits of organic material Coal buried remains of plant life o o Many types of limestone are made primarily of the shells of once living things o Made of calcium carbonate o Typically form in salty water and thus marine or brackish lakes Chemical sedimentary rocks sediment is in the form of dissolved bits ions that precipitate out of water Detrital sedimentary rocks sediment is grains of various sizes weathered from previously existing rock cemented together by minerals in the ground and water By far the most common in which dinosaur fossils are found o o Major types Breccia poorly sorted angular and rounded close to source Conglomerate very well sorted and round far from source Sandstone formed by relatively well sorted well rounded particles deposited in many environments deserts beaches river beds nearshore marine etc o Detrital sedimentary cycle Uplift to erosion to transport to deposition to lithification typically cementation Uplift pushing up once buried rocks and exposing them to the surface elements This source rock experiences erosion weathered away and broken up by wind rain water plant roots gravity etc The broken fragments sediment are transported by water wind glacial ice etc Sediment is deposited at some location stream bed banks of a river desert delta lake Energy of the environment how fast the water or wind was moving different sized particles of sediment Sedimentary structures traces left in the sediment by various processes before lithification Mud Crack indicate that mud was wet and then dried and then buried Ripple Marks indicate wind Crossbeds ripple marks in cross section formed by currents wind or water Trough Crossbeds shifting winds produced lots of sand beaches and dessart Raindrop marks indicates wet surface Coal Beds indicates abundant plant life that was buried faster than it could decay 2 major types of fossils Body Fossils the physical remains of an organism preserved in rock Trace Fossils the record of organisms behavior preserved in rock Taphonomy The study of burial and fossilization Modes of Preservation Unaltered bone simple burial some weathering Permineralized most common mode of preservation of dinosaur body fossils Replacement grades from permineralization Carbonization organic material is distilled under pressure Many material is lost but carbon film left behind Impressions of dinosaur skin can form if the body was pressed into the mud Different organisms have different potential for fossilization Hard parts vs no hard parts Lived in erosive environments e g mountains vs depositional environments Lived in accessible vs inaccessible environments 2 aspects of time to consider Relative Time sequence of events without consideration of amount of time Numerical Time dates or durations of events in terms of seconds years millions of years etc Good Index fossil VERY common hard parts geographic range different environments distinctive features short time duration a few million years at most Dating techniques Radiometric dating Radioactive materials decay at predictable rate known as the half life only for igneous rocks Magnetostratigraphy a magnet s north pole points towards geographic North and sometimes toward geographic South The 3 eras The Paleozoic Era ancient life era The Mesozoic Era middle life era the Age of Dinosaurs The Cenozoic Era recent life era the Age of Mammals We are still in the Cenozoic Era The oldest furthest from us in time is the Triassic Period crurotarsan crocodile ancestors ruling The middle one is the Jurassic Period dinosaurs The youngest closest to us in time is the Cretaceous Period dinosaurs Convergent Boundaries when plates come together Mountain Ranges are erosional water is depositional EXAM 2 Carolus Linnaeus System of classification codified by Carolus Linnaeus 18th Century Swedish botanist Father of Taxonomy Many of his principles such as Latin names for organisms and the use of genus and species still used today Natural Selection Does NOT happen to individuals only to populations lineages Analogous to artificial selection domestication but operates o On all traits rather than a few humans can keep alive crops farm animals or pets that might otherwise die in the wild obviously wild plants and animals don t have that help o Over vast amounts of geologic time rather than just a few generations Does NOT require simple things evolving into complex sometimes a simplified mutation of a structure might be advantageous than the ancestral complex one hence vestigial organs Cannot evolve towards something with a goal in mind only favors variations that are advantageous at the time of selection Darwin Wallace s observations Variability There is variation in all populations no two members of a population are totally identical Heritability Some but not all variation is inherited Mutations are new variations in heritable traits caused by miscopied DNA Superfecundity Organisms produced far more offspring than can possibly survive Willi Hennig considered the founder of phylogenetic systematics also known as cladistics Comparative anatomy Scientific study to describe the bodies of organisms in terms of their homologous structures Homology vs Analogy Homology traits inherited by two different organisms from a common ancestor o Homologies the same anatomical structures body parts are