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Lecture 3

GSC 102 Lecture 3: GSC Exam 3 Study Guide

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Department
Geological Sciences
Course
GSC 102
Professor
Leech Peter
Semester
Spring

Description
Exam 3 Notes 11/2/2016 3:24:00 PM 24. Triassic (252-201 million years ago) • First period of the Mesozoic • Amphibians made it thru the Permian-Triassic extinction event • Early Triassic – the temnospondyls gave rise to genus Triadobatrachus (in Madagascar) o AKA proto-frog o Evolution of the modern frog • Lystrosaurus is a dicynodont (a type of synapsid) which survived the PT Extinction o During Early Triassic, make up 95% of all terrestrial vertebrates • Mammal – having a dentary-squamosal joint o Have one jaw bone, three ear bones o Reptiles have more jaw bones and one ear bone • During the Triassic (200 million years ago), first mammal like animals appear like the Megazostrodon o Mammals are characterized by having modified sweat glands called mammary glands • Pangea is arid; Sauropsids may conserve water better than synapsids • Living descendents of the synapsids have glandular skin and need to flush out their nitrogen waste with water • Sauropsids split into: o LEPIDOSAURS include the modern snakes and lizards (the “scaly lizards”) o ARCHOSAURS include the dinosaurs and crocodilians • Lepidosaurs give rise to the MESOZOIC MARINE REPTILES (not dinosaurs) o Lepidosaurida (possibly) produced the first ICHTHYOSAURS during the Triassic (probably) o Ichthyosaurs are one of three main kinds of MMR we’ll see • The rise of DUROPHAGY also drives the MESOZOIC MARINE REVOLUTION • Organisms which attached to the sea floor and were easily plucked off (like the Paleozoic crinoids and brachiopods) did not do well o They are largely replaced by organisms which can cling tightly to the substrate • The Triassic land is dominated by NONDINOSAUR ARCHOSAURS o The top carnivores are relatives of the early ancestors of the crocodiles— CROCODYLOMORPHS • The first crocodylomorph archosaurs show up near the end of the Triassic • Non-dinosaur archosaurs also dominate the herbivores • Members of order Rhynchosaur may have made up 40-60% of animals in certain places during the Triassic • Pterosaurs make an appearance during the Late Triassic (not dinosaurs) o Early pterosaurs are distinguished by their tails, which later pterosaurs do not have. • Dinosaurs are defined as everything which evolved from the most recent common ancestor of Triceratops and birds, minus the birds • The earliest true dinosaur is probably something like Eoraptor (“Dawn hunter”) o Small, bipedal, omnivorous • Alternatively, the dinosaurs are all of the archosaurs which are not crocodilian or pterosaurs • The dinosaurs are split into two main groups: o ORNITHISCHIA (bird-hipped dinosaurs) o SAURISCHIA (lizard-hipped dinosaurs) ▪ This distinction is exactly what it sounds like—a fundamental difference in the structure of the hip • By the end of the Triassic, the lizard-hipped dinosaurs had split into two main groups: o THERAPODS (BIPEDAL CARNIVORES) o PROSAUROPODS, later develop into SAUROPODS (LONG-NECKED HERBIVORES • Diplodocus is a SAUROPOD from the Late Jurassic • Pisanosaurus, from 220 Ma, represents an early bird-hipped dinosaur o 3-4 feet long • Bird-hipped dinosaurs will include every dinosaur that is not a therapod or sauropod o Stegosaurus is a bird-hipped dinosaur from the Late Jurassic o Triceratops is a bird-hipped dinosaur from the Late Cretaceous • The end of the Triassic is marked by the production of the CENTRAL ATLANTIC MAGMATIC PROVINCE (CAMP) o New Jersey Palisades are part of CAMP 25. Jurassic (200-145 million years ago) • Pangaea begins to break into LAURASIA to the North and GONDWANA to the South, separated by the TETHYS SEA • Climate is generally warm, non-glaciated, with low seasonality • In the enclosed basin of the Gulf of Mexico and the Western Interior Seaway, salt and gypsum began to accumulate • Salt, under high pressure, tends to flow. It is also low in density compared to other rocks, so it tends to push up through newer sediments and form SALT DOMES o As salt domes rise up, they form bulges in the overlying sediment. Oil and gas float to the top of these bulges • BONE WARS (EDWARD DRINKER COPE VS. OTHNIEL CHARLES MARSH) o One of the key locations of the Bone Wars was the MORRISON FORMATION, an extremely fossil-rich Jurassic sedimentary rocks • Sauropods (lizard-hipped, quadrupedal, long-necked herbivores) evolved from small, bipedal ancestors • Almost all dinosaurs, even quadrupedal dinosaurs, had back legs bigger than their front legs • Cope’s Rule suggests that population lineages get larger over time. Large size has many advantages (up to a point) o Sauropods become very large, very quickly, and then mostly plateau through the Cretaceous • Evolutionary cascade models suggest multiple causes and feedbacks contributing to increasing size in sauropods • Sauropod neck posture is still a controversial issue, and involves questions of neck flexibility, energy expenditure, and blood pressure o A recent hypothesis puts Diplodocus’s neck at around 45° • In contrast to the diplodocoids, the TITANOSAURIFORMS tended to have longer front legs, a more upright neck, and shorter tails o Titanosauriforms include Brachiosaurus • Amphicoelias fragillimus may be the largest land animal of all time, at 200 feet long and 120 tons o Amphicoelias fragilimus is only known from a drawing of a partial vertebrate made in the 1870s. (The actual fossil is thought to have crumbled) • Sauropods had relatively small heads, and small, peg-like teeth o The gigantic, barrel-like bodies of the sauropods probably allowed for extensive fermentation of vegetation o Rocks which appear to be GASTROLITHS have been associated with some sauropod fossils • The top predators of the late Jurassic were large therapods like Allosaurus o Allosaurus was around 30 feet, and approximately 2.5 tons. (Compare to Tyrannosaurus rex at 40 feet, 5-7 tons) o Compared to the later Tyrannosaurus rex, Allosaurus had relatively weak jaw muscles, extremely well articulated jaw, strong teeth, and strong neck o Certain of the therapods almost certainly had feathers or partial feathering • This is Sinosauropteryx, from the Cretaceous • Studies of feathers which have been preserved in amber give us a good look at how feathers evolved • Their original purpose was probably for display, and early feathers were probably similar to this iguana’s spines o Early feathers also probably helped insulate the feathered dinosaurs • Remains of theropods in brooding position, and trackways of mature and juvenile theropods together all support the theory that theropods brooded their eggs and cared for their young o Another piece of evidence for brooding in theropods comes from the pores in their eggs • Archaeopteryx (151-149 million years ago, late Jurassic) is considered to be the first member of the class Aves, the birds. o Archaeopteryx was probably a glider rather than a true flyer • So far, we’ve separated the dinosaurs into the bird-hipped ornithischia, and the lizard-hipped saurischia. We’ve further separated the lizard- hipped dinosaurs into the sauropods and therapods o The textbook separates the bird-hipped dinosaurs (and the therapods) into several groups o Bird-footed dinosaurs o Rimmed-headed dinosaurs o Armored dinosaurs • Armored dinosaurs: Stegosaurus and Ankylosaurus o Both descend form early Jurassic armored dinorsaurs like the Scelidosaurus • Stegosaurus (150-155 Ma) is representative of the low browsing herbivores of the Jurassic. It is also just one of many stegosaurians • Kentrosaurus (152 Ma) is a very common, but more obscure armored dinosaur. • Like the sauropods, the plated dinosaurs had small, weak teeth and jaws o Unlike sauropods, no gastroliths have been found associated with plated dinosaurs • Pterodactylus antiquus (151-148 Ma) is a SPECIES of Pterosaur. Note the PYCNOFIBERS and short tail • The Lepidosaurs continue to dominate the oceans of the Jurassic o Early forms of the PLESIOSAURS and ICHTHYOSAURS during the Triassic • The ICHTHYOSAURS, like Ichthyosaurus are the top marine predator of the late Triassic and early Jurassic o However, by the end of the Jurassic, they have been knocked off the top spot • Semi-aquatic trassic Lepidosaurs of the Triassic, develop fully into the PLESIOSAURS of the Jurassic (200- 175 Ma) • In mammal news, MONOTREMES probably appear during the Jurassic o Monotremes have mammary glands, but no nipples, and lay eggs o Because the continents are still largely together, monotremes can travel almost world-wide o The only monotremes alive today are the PLATYPUS and the ECHIDNAS, both native to Australia 26. The Cretaceous (145-66 million years ago) • Rising sea levels during the Cretaceous contribute to fragmentation of the continents • Continents continue to rift • Warm climate also means relatively high sea levels • Erosion of the Appalachian mountains created sedimentary rocks to the east of the mountains • After sea levels fell, erosion began o The sedimentary rocks erode faster than the igneous and metamorphic rocks of the mountains, creating a “step” in the landscape—the FALL LINE • The forests of the Mesozoic would be dominated by gymnosperm conifers at high latitudes and CYCADS in the tropics • It is hypothesized that low browsers like Stegosaurus contributed to the spread of a new, faster growing, faster breeding type of plant • In the Jurassic, the first ANGIOSPERMS appear o Angiosperms have an enclosed seed, or fruit o Angiosperms are generally FLOWERING PLANTS o Angiosperms provide a great example of coevolution, since they use pollinators to efficiently spread their pollen • During the Cretaceous, the social hymenoptera (bees, wasps, ants) appear or spread, as well as the lepidoptera (butterflies and moths) • The beaks of CERATOPSIANS like Triceratops were probably much better at shredding vegetation • Like the other dinosaurs the rimmed-headed CERATOPSIANS began as small bipeds • By the end of the Cretaceous, they were rhino-sized quadrupeds • In some parts of the US, ceratopsian fossils account for 80% of all fossils • Bird-footed dinosaurs (Ornithopoda) o Iguanadon (126-125 Ma) 30-40 feet o Parasaurolophus, a DUCK-BILLED DINOSAUR or HADROSAUR (76- 73 Ma) 30 feet • The bird-footed dinosaurs not only have better teeth than the sauropods, they can CHEW! (No other reptile can chew) • While bird-footed dinosaurs take over in the Northern Hemisphere, sauropods hang on in the south o One of the largest known (real) dinosaurs (or land animals ever) is the Late Cretaceous sauropod Argentinosaurus, at 100-130 feet long and 80-100 tons • VELOCIRAPTOR APPEARS o has quill knobs, suggesting that, like other therapods, it was feathered • TYRANNOSAURUS REX o (up to 40 feet and 8 tons) o Northern Hemisphere o Active hunter or scavenger? o had BINOCULAR vision (predator trait) o Healed Hadrosaur bone around a Tyrannosaurus tooth suggest active predation • Giganotosaurus 40 feet, 6-13 tons, Southern Hemisphere • Tarbosaurus 30-40 feet, 4-5 tons, Asia • So the Jurassic sauropods and plated dinosaurs are largely replaced by birdfooted and rimmed-headed dinosaurs in the Cretaceous, and they’re all hunted by therapods • Pterosaurs diversify. Pteranodon species exhibit large crests on their heads o Some researchers have previously hypothesized that these are for thermal regulation or for steering • Pterosaurs are flying animals, so we usually imagine them flying o But many pterosaurs were marine animals, and probably spent some time floating, like sea birds or ducks o Preserved fossil trackways suggest that pterosaurs landed like ducks, dragging their hind feet, and then walked around on all fours • Quetzalcoatlus, one of the largest pterosaurs o Believed to be the largest known flying animal of all time, with a wing span of 30-40 feet and a height of almost 20 feet when standing • Birds become more bird-like o Ichthyornis has lost the long bony tail and claws of Archaeopteryx, but retains the teeth • Sharing the skies with the birds and the bees (and the pterosaurs), are the four-winged dinosaurs, such as this Microraptor • In the seas, a new type of lepidosaur has shown up—the MOSASAURS • Plesiosaurs and mosasaurs dominate the Cretaceous o Ichthyosaurs decline • Monotremes lay eggs and lack nipples (platypus and echidnas) • Marsupials have pouches (kangaroos and koalas) o True marsupials probably develop in North America around 100 Ma o From there they spread to South America by 65 Ma and Australia (via Antarctica) before 50 Ma. • Placentals have internal gestation (the other mammals) • Protomarsupials show up in China around 125 Ma • Placental mammals are defined by a placenta—an organ which connects the fetus to the uterine wall allowing nutrient uptake, waste elimination, and gas exchange, but insulating the fetus from the mother’s immune system. • Placental mammals generally outcompete monotremes and marsupials, except in Australia, which placental mammals cannot get to 27. The Cretaceous-Tertiary Extinction • AKA end-Cretaceous or Cretaceous-Paleogene Extinction • Pterosaurs are in decline (reason unknown) • Ichthyosaurs are possibly extinct by the end of the Cretaceous • 75% of marine species, 100% of non-avian dinosaurs are extinct • Deccan traps are 2000m thick and cover 200,000 square miles • Walter Alvarez wanted to study how fast the K-Pg event had been, so he sent a sample of the clay in the K-Pg layer to his father to look for iridium o Massive amounts of iridium were found in the middle of the Deccan traps o There is little iridium on the earth’s crust, but some in the mantle and outer core • K-Pg clay layer also contained shocked quartz • Third component of K-Pg layer is Tektites • Evidence suggests a catastrophic bolide impact near N. America o In North America, there are layers of broken up rocks. Further from North America, there are thinner layers of smaller debris. o Deposits of unsorted sediment up to 5 feet thick in Missouri suggest a 200 meter tall megatsunami in North America o (Looking at the amount of iridium) Asteroid size is about 5 miles in diameter ▪ Created crater 110 miles across and 20 miles deep • Discovered evidence for a giant impact on the Yucutan peninsula at CHICXULUB at the same time as the K-Pg boundary o Impact of Chicxulub asteroid would have thrown enough dust into the atmosphere to darken the skies for up to a year (IMPACT WINTER) • The site of asteroid impact is rich in gypsum (drywall material) o Gypsum is rich in sulfur o When sulfur is gasified, it tends to form aerosols o Sulfur aerosols could have extended the impact winter from years to decades • It is hypothesized that reduced sunlight and sudden cooling caused a mass dying of photosynthesizers o If photosynthesizers go extinct, then stuff that eats photosynthesizers goes extinct o If stuff that eats photosynthesizers goes extinct, then stuff that eats stuff that eats photosynthesizers goes extinct. • The survivors are small, burrowing, omnivorous, detritus-eating animals—the mammals • At least 40% of birds went extinct 28. The Paleogene (65-23 million years ago) • Dinosaurs went extinct 65 million years ago  Age of Mammals • Continents are close to their modern positions, still separate • 60 million years ago – India collides with Eurasia and forms the Mialayan Plateau (youngest mountain formations on Earth) o Weathers quickly  pulls CO2 out of atmosphere, cooling the Earth • Birds undergo a massive radiation in the early Paleogene • The first marsupials and monotremes appear while Pangaea is still connected and while dinosaurs still exist o Monotremes lay eggs o Marsupials have pouches o Placentals have internal gestation • Australia never “reconnected” with other continents, so its ecosystem remains unique o Besides bats and some rodents, any placental mammals in Australia, like dingos and rabbits, were introduced by humans o After the K-Pg extinction, mammals are mostly represented by small, shrew-like animals on all of the continents • The AFROTHERIA consist of the SIRENIA (sea cows) PROBISCIDAE (elephants), and SOME OTHER GUYS (aardvarks, golden moles, and tenrecs) o Moeritherium, 2-3 feet tall, ~500 lbs, middle Paleogene o Deinotherium, 12-13 feet tall, 9-12 tons, late Paleogene • Laurasiatheriaare a group of placental animals with evolved in the Northern continents o It consists of the carnivores, the even-toed hoofed mammals, and odd-toed hoofed mammals (as well as hedgehogs, bats, and pangolins) • The CARNIVORA (mostly meateating mammals) also begin to radiate during the early Paleogene o Around 42 million years ago, they split into two groups: the cat-like FELIFORMS and the dog-like CANIFORMS • The phylogenic tree of the Carnivora also contains a couple of surprises o For example, the seals, sealions, and walruses are all part of the caniforms. • The odd-toed ungulates, or odd-toed hoofed mammals, are today represented by the horses and rhinoceroses • Even-toed ungulates include most economically-used mammals besides the horses: pigs, goats and sheep, camels and llamas, deer and antelope o The giraffes and hippopotamuses are also even-toed ungulates. And our final set of even-toed ungulates are dolphins and whales • The blue whale, an even-toed ungulate, is the heaviest animal ever (170 tons), and a contender for the longest (100 feet) • The earliest ancestor of the horse is the forest-dwelling EOHIPPUS (56-48 million years ago). Notice the splayed (although hooved) toes, adapted for walking on soft forest floors • Grasses really begin to take off around 55 million years ago o They are fast growing, which allows them to quickly colonize areas where trees have been destroyed o They also grow from the bottom up, which means they can survive being eaten and trampled o One disadvantage that grasses have is that trees can shade them out o Many mammals evolved to eat grasses, creating a positive feedback which converts forests into grasslands • As grasslands expanded, the early horses adapted o Teeth became better adapted to grind grass rather than chew softer forest leaves o The splayed toes of Eohippus grew together to allow the horses to sprint on their toes (eventually a single toe), and their legs lengthened o Their toe hardened into a hoof • By the end of the Paleogene, the largest land mammals have become comparable in size to dinosaurs (except the sauropods) • Paraceratherium, of the late Paleogene, may be the largest land mammal to ever live 29. The Neogene • Antarctica moves towards the South Pole; climate is colder • Around 23 million years ago, the Drake Passage opened o This allowed the formation of the Circumpolar Current which effectively cut off Antarctica from the rest of the Earth’s climate, making Antarctica even cooler • The Antarctic ice sheet is relatively stable o High albedo of ice keeps it cool o High altitude of ice keeps it cool o Land cools more quickly than water o Circumpolar current isolates Antarctica from rest of climate • In the Early Paleogene, Europe is separated from Asia, and placental mammals are migrating from Asia into North America, and then into Europe o By the end of the Paleogene, the continents were beginning to reconnect o As Europe and Asia connect, 60% of European mammals become extinct o This is called the Grande Coupure, or Great Break • As Africa, Eurasia, and North America reconnect, even- and odd-toed ungulates, elephants, and carnivores become largely homogenized • By the end of the Neogene, South America was beginning to reconnect with North America • During most of the Paleogene and Neogene, South America is populated by marsupials, the native Xenarthra placental mammals, and a few introduced placental mammals • Xenarthra – “primitive” placental mammals o Also include Glyptodon and the gigantic GROUND SLOTH • The CAVIOMORPH RODENTS appear around 35 million years ago, either from N. America or Africa o The caviomorph rodents include the capybara, the la
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