Unit 4: DinosaursLecture 1Definitions:• Paleontologists : people who study ancient organisms• Paleobiology : the study of the lives of ancient organisms (physiology, behavior, ecology, functional anatomy)The History of the Field:1. First writing about dinos came out of china. They called them dragon bones. “Dragon Bones” from long dead serpents were unearthed for centuries for medical purposes: in China they would dig them up turn them into powder and sell them as a Viagra. 2. In 1671: “Giant Human bone” found in Europe.. They believed it was a scrotum of a giant human, became known as : Scrotum humanum.. First dino to be named. Turned out to be a real dino and not a Giant human.3. In 1770 a 40ft long sea monster named Mosasaurus was found in Holland. 4. In 1824 Megalosaurus “big lizard” was discovered but no one paid attention because they thought they were just over sized lizards.5. Around the same time giant teeth were also found. Again just thought it was a big lizard. Finally once they named it Iguanodon, it got a huge amount attention because it was a plant-eating lizard.6. The first dinos were depicted as giant versions of currently living lizard species.7. Richard Owen: noted these bones were different than current reptiles. In 1842, he designated them as a new group of reptiles: Dinosauria : “Fearfully Great Reptiles”. Again before he did this people just believed these bones were just giant lizards that were living at the time. a. Owen made several mistakes: they made all dinos walk on four legs. What Makes a Dina a Dina?• Have teeth in sockets like crocodiles• Pterosaurs (flying reptiles) and Dinomorphs: Pterosaurs and Dinosauromorphs had metatarsal ankles- could stand up right .Unique Features:• Three or more sacral vertebrae= fused backbones in hip region• Hands with three main fingers• Perforate acetabula- hole where the thigh bone attached goes all the way through the hipBy the late 1800a there was enough evidence to realize there were two types of dinosaurs:1. Ornithischians w/ hips shaped like birds2. Saursichians w/ hips shaped like lizardsDinosaur Renaissance• In 1964 Dinosaur Renaissance occurred thanks to the Deinonychus (real raptor from Jurassic Park). It changed the view on dinos.• Robert Bakker : all dinosaurs were athletic and probably more like the birds we have living today. People became really interested and everyone began to study them to prove him wrong. It turned out that Bakker was partially right.• Cladistics - a way to organize physical features, also caused people to look into dinosaurs.Lecture 2: The Age of DinosaursLived: 238 million year until 65.5 million years ago during what is called the Mesozoic Era or the Age of Dinosaurs.• Age of dinos broken into three periods: Triassic, Jurassic, Cretaceous• How do we know the ages? Observe the rockso For dinosaurs are sediments Uranium 235 is the best. It is formed in the Earth. It breaks down over time after 704 million years it will break down by about 50% (half life). Carbon dating has too short of a half life to be of use for dinos.Climate: we know from the kinds of plants, animals, and temperature sensitive isotopes that…• World was warmer• Arid in equatorial regions• Like Florida in middle latitudes• Continents moved driven by volcanic sea floor spreading- Plate tectonicsTriassic Era: Pangea, Continents adjoinedCretaceous Era: Dino distributions have helped to figure out where the continents were and explain their distribution.• With warmer Earth there was no ice at the poles- oceans were higher; seaways crossed the continents (warm shallow sea); this influenced where and how dinosaurs traveled; dinosaurs had less land to live on compared to today.Vegetation:• Triassic & Jurassic plants: large giant trees, not much to forage on, ginkos, pine trees, cycads in dry areas, conifers; less ground cover no grass. Trees had great height and chemical defenses and poor ability to regenerate.• By the middle of the Cretaceous Period flowering plants (angiosperms finally show up= ground cover)• These plants regenerate quickly to survive foragingDinosaur relatives:• Crocodilians and their close relatives first were terrestrial, land dwellers; some where even bipedal; some were fully aquatic sea monsters; some were just like today’s crocodiles• Deinosuchus growth: grew at rates like living alligators, very unlike the dinosaur pattern. Looked at growth plates these animals just kept growing slowly and became gigantic.• Supercroc: Sacrosuchus- 40ft from Africa; had to figure out the bite force they used a bite force meter to measure the American crocodiles and then used that and scaled it up to meet the supercroc; * saltwater crocodile 3,700lbs-= highest bite force ever measured. • Calculated that supercroc and the Deinosuchus ~31,00lbs!• Lots of sea monsters Ichthyosaurs were dolphin like retiles. We know their fin profile from impressions.• Long-Necked Plesiosaurs- the Loch Ness Monster the loch only about 10,000 years ago so it would have had to have gotten in fairly recently• Mosasuars: aquatic animals closely related to today’s monitor- lizard• The real giants were the Quetalcoatalids w/ 35-40 ft wingspans! They were always found well inland and are thought to have been dinosaur scavengers.• Mammals appear at the same time as dinosaurs mostly rat or possum-sixed throughout the Age of Dinosaurs• In the late Jurassic birds show up• Vegavis- duck found in Antarctica; this leads to believe there were also chickens present.• Fossils are remains of ancient life: for dinosaurs we tend to think just bones but that isn’t the case Trace Fossils not actual physical remainsTrace Fossils: tracks, eggs, skin impressions, stomach stones, bite marks, coprolites (dino poop).• Skin impressions: reveal aspects of thermoregulation & display features• Gastroloths (gizzard stones) how they break down food• Eggs & nest: reveal aspects of ovaries, behavior in laying, size of young, etc• Bite marks: who ate who; damage they could produce, biting force• Coprolies: dino dung; tells what they ate; if they have strong digestive acids; how much dentition broke down itemsWhere do we find dinosaurs? • Rocks: sedimentary rocks- composed of consolidated sediments from rivers or desert• Often once buried, minerals precipitate through the pores in the bones and harden them making them more resistant.
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