Geologic Time Scale
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Diversity Partitioning During the Cambrian Radiation
Diversity partitioning during the Cambrian radiation Lin Naa,1 and Wolfgang Kiesslinga,b aGeoZentrum Nordbayern, Paleobiology and Paleoenvironments, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany; and bMuseum für Naturkunde, Leibniz Institute for Research on Evolution and Biodiversity at the Humboldt University Berlin, 10115 Berlin, Germany Edited by Douglas H. Erwin, Smithsonian National Museum of Natural History, Washington, DC, and accepted by the Editorial Board March 10, 2015 (received for review January 2, 2015) The fossil record offers unique insights into the environmental and Results geographic partitioning of biodiversity during global diversifica- Raw gamma diversity exhibits a strong increase in the first three tions. We explored biodiversity patterns during the Cambrian Cambrian stages (informally referred to as early Cambrian in this radiation, the most dramatic radiation in Earth history. We as- work) (Fig. 1A). Gamma diversity dropped in Stage 4 and de- sessed how the overall increase in global diversity was partitioned clined further through the rest of the Cambrian. The pattern is between within-community (alpha) and between-community (beta) robust to sampling standardization (Fig. 1B) and insensitive to components and how beta diversity was partitioned among environ- including or excluding the archaeocyath sponges, which are po- ments and geographic regions. Changes in gamma diversity in the tentially oversplit (16). Alpha and beta diversity increased from Cambrian were chiefly driven by changes in beta diversity. The the Fortunian to Stage 3, and fluctuated erratically through the combined trajectories of alpha and beta diversity during the initial following stages (Fig. 2). Our estimate of alpha (and indirectly diversification suggest low competition and high predation within beta) diversity is based on the number of genera in published communities. -
Triassic- Jurassic Stratigraphy Of
Triassic- Jurassic Stratigraphy of the <JF C7 JL / Culpfeper and B arbour sville Basins, VirginiaC7 and Maryland/ ll.S. PAPER Triassic-Jurassic Stratigraphy of the Culpeper and Barboursville Basins, Virginia and Maryland By K.Y. LEE and AJ. FROELICH U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1472 A clarification of the Triassic--Jurassic stratigraphic sequences, sedimentation, and depositional environments UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1989 DEPARTMENT OF THE INTERIOR MANUEL LUJAN, Jr., Secretary U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government Library of Congress Cataloging in Publication Data Lee, K.Y. Triassic-Jurassic stratigraphy of the Culpeper and Barboursville basins, Virginia and Maryland. (U.S. Geological Survey professional paper ; 1472) Bibliography: p. Supt. of Docs. no. : I 19.16:1472 1. Geology, Stratigraphic Triassic. 2. Geology, Stratigraphic Jurassic. 3. Geology Culpeper Basin (Va. and Md.) 4. Geology Virginia Barboursville Basin. I. Froelich, A.J. (Albert Joseph), 1929- II. Title. III. Series. QE676.L44 1989 551.7'62'09755 87-600318 For sale by the Books and Open-File Reports Section, U.S. Geological Survey, Federal Center, Box 25425, Denver, CO 80225 CONTENTS Page Page Abstract.......................................................................................................... 1 Stratigraphy Continued Introduction... .......................................................................................... -
Asteroid Impact, Not Volcanism, Caused the End-Cretaceous Dinosaur Extinction
Asteroid impact, not volcanism, caused the end-Cretaceous dinosaur extinction Alfio Alessandro Chiarenzaa,b,1,2, Alexander Farnsworthc,1, Philip D. Mannionb, Daniel J. Luntc, Paul J. Valdesc, Joanna V. Morgana, and Peter A. Allisona aDepartment of Earth Science and Engineering, Imperial College London, South Kensington, SW7 2AZ London, United Kingdom; bDepartment of Earth Sciences, University College London, WC1E 6BT London, United Kingdom; and cSchool of Geographical Sciences, University of Bristol, BS8 1TH Bristol, United Kingdom Edited by Nils Chr. Stenseth, University of Oslo, Oslo, Norway, and approved May 21, 2020 (received for review April 1, 2020) The Cretaceous/Paleogene mass extinction, 66 Ma, included the (17). However, the timing and size of each eruptive event are demise of non-avian dinosaurs. Intense debate has focused on the highly contentious in relation to the mass extinction event (8–10). relative roles of Deccan volcanism and the Chicxulub asteroid im- An asteroid, ∼10 km in diameter, impacted at Chicxulub, in pact as kill mechanisms for this event. Here, we combine fossil- the present-day Gulf of Mexico, 66 Ma (4, 18, 19), leaving a crater occurrence data with paleoclimate and habitat suitability models ∼180 to 200 km in diameter (Fig. 1A). This impactor struck car- to evaluate dinosaur habitability in the wake of various asteroid bonate and sulfate-rich sediments, leading to the ejection and impact and Deccan volcanism scenarios. Asteroid impact models global dispersal of large quantities of dust, ash, sulfur, and other generate a prolonged cold winter that suppresses potential global aerosols into the atmosphere (4, 18–20). These atmospheric dinosaur habitats. -
Tracking the Evolution of the Grenville Foreland Basin
Krabbendam et al: Detrital zircon and rutile in the Sleat and Torridon groups Tracking the evolution of the Grenvillian Foreland Basin: constraints from sedimentology and detrital zircon and rutile in the Sleat and Torridon groups, Scotland Maarten Krabbendam a, *, Helen Bonsor a, Matthew S.A. Horstwood b, Toby Rivers c a) British Geological Survey, Lyell Centre, Research Avenue South, Edinburgh EH14 4AP, Scotland, UK b) NERC Isotope Geosciences Laboratory, British Geological Survey, Keyworth NG12 5GG, UK c) Department of Earth Sciences, Memorial University of Newfoundland, St. John’s, NL Canada A1B 3X5 * Corresponding author. Email: [email protected] Keywords: foreland basin; provenance; detritus; Grenville Orogen; U-Pb geochronology; Neoproterozoic 1 Krabbendam et al: Detrital zircon and rutile in the Sleat and Torridon groups Abstract The Grenville Orogen, although occupying a key position in the Rodinia supercontinent, lacks a clear foreland basin in its type area in eastern Canada. Early Neoproterozoic siliciclastic rocks in northern Scotland, however, are now interpreted as remnants of a proximal Grenvillian foreland basin. Analysis of the sedimentology and detrital zircon and rutile of the Torridon and underlying Sleat groups provide new constraints on the evolution of this basin. Youngest U-Pb detrital zircon grains yield ages of 1070-990 Ma in both groups, consistent with a Grenvillian source. The proportions of older age components vary throughout the stratigraphy. The lower Sleat Group shows a dominant ca. 1750 Ma peak, likely derived from local Rhinnian rocks in Scotland and Ireland uplifted within the Grenville Orogen. In the upper Sleat Group and Torridon Group, detrital zircon peaks at ca. -
The Geologic Time Scale Is the Eon
Exploring Geologic Time Poster Illustrated Teacher's Guide #35-1145 Paper #35-1146 Laminated Background Geologic Time Scale Basics The history of the Earth covers a vast expanse of time, so scientists divide it into smaller sections that are associ- ated with particular events that have occurred in the past.The approximate time range of each time span is shown on the poster.The largest time span of the geologic time scale is the eon. It is an indefinitely long period of time that contains at least two eras. Geologic time is divided into two eons.The more ancient eon is called the Precambrian, and the more recent is the Phanerozoic. Each eon is subdivided into smaller spans called eras.The Precambrian eon is divided from most ancient into the Hadean era, Archean era, and Proterozoic era. See Figure 1. Precambrian Eon Proterozoic Era 2500 - 550 million years ago Archaean Era 3800 - 2500 million years ago Hadean Era 4600 - 3800 million years ago Figure 1. Eras of the Precambrian Eon Single-celled and simple multicelled organisms first developed during the Precambrian eon. There are many fos- sils from this time because the sea-dwelling creatures were trapped in sediments and preserved. The Phanerozoic eon is subdivided into three eras – the Paleozoic era, Mesozoic era, and Cenozoic era. An era is often divided into several smaller time spans called periods. For example, the Paleozoic era is divided into the Cambrian, Ordovician, Silurian, Devonian, Carboniferous,and Permian periods. Paleozoic Era Permian Period 300 - 250 million years ago Carboniferous Period 350 - 300 million years ago Devonian Period 400 - 350 million years ago Silurian Period 450 - 400 million years ago Ordovician Period 500 - 450 million years ago Cambrian Period 550 - 500 million years ago Figure 2. -
The Cenozoic Era - Nýlífsöld 65 MY-Present Jarðsaga 2 Ólafur Ingólfsson Origin of the Term: the Tertiary Tertiary System
The Cenozoic Era - Nýlífsöld 65 MY-Present Jarðsaga 2 Ólafur Ingólfsson Origin of the Term: The Tertiary Tertiary System. [1760] Named by Giovanni Arduino Period as the uppermost part of his 65-1.8 MY three-fold subdivision of mountains in northern Italy. The Tertiary became a formal period and system when Lyell published his work describing further subdivisions of the Tertiary. The Tertiary Period is divided into five epochs (tímar): Paleocene (65-56 MY), Eocene (56-34 MY), Oligocene (34-24 MY), Miocene (24-5,3 MY), and Pliocene (5,3-1,8 MY). Confusing set of stratigraphic terms... More than 95% of the Cenozoic era belongs to the Tertiary period. During the 18th century the names Primary, Secondary, and Tertiary were given by Giovanni Arduino to successive rock strata, the Primary being the oldest, the Tertiary the more recent. In 1829 a fourth division, the Quaternary, was added by P. G. Desnoyers. These terms were later abandoned, the Primary becoming the Paleozoic Era, and the Secondary the Mesozoic. But Tertiary and Quaternary were retained for the two main stages of the Cenozoic. Attempts to replace the "Tertiary" with a more reasonable division of “Palaeogene” (early Tertiary) and “Neogene” (later Tertiary and Quaternary) have not been very successful. Stanley uses this division. The World at the K/T Boundary Paleocene plate tectonics During the Paleocene, the inland seas of the Cretaceous Period dry up, exposing large land areas in North America and Eurasia. Australia begins to separate from Antarctica, and Greenland splits from North America. A remnant Tethys Sea persists in the equatorial region. -
Making a Timeline Rope
Making a Timeline Rope Background: Your timeline rope invites students to focus on recent periods of geologic time. This rope demonstrates four periods and seven epochs, beginning with the Jurassic Period in the Mesozoic Era, in the Phanerozoic Eon, and ending at the present time, in the Holocene Epoch, in the Quaternary Period of the Cenozoic Era, in the Phanerozoic Eon. Standards: SC.D.1.2.3 SC.D.1.2.5 SC.D.1.3.1 SC.D.1.3.2 SC.D.1.3.3 MA.1.G.5.1 MA.1.G.5.2 MA.2.G.3.4 MA.2.G.3.1 MA.3.G.5.2 MA.4.G.3.3 MA.6.A.5.1 MA.8.A.1.3 SC.912.E.5.3 SC.912.E.6.4 SC.912.E.6.5 SC.912.N.3.1 SC.912.N.3.5 Objectives: − Analyze how specific geological processes and features are expressed in Florida and elsewhere − Describe the geological development of the present day oceans and identify commonly found features − Understand the function of models in science, and identify the wide range of models used. − Compare, contrast, and convert units of measure Vocabulary: Geologists and paleontologists give names to spans of many years. Spans are approximate; they relate more to fossil age ranges than to absolute years. Experts use a common vocabulary. Eon: Largest division of geologic time. Each eon contains several periods and can last for hundreds of millions to billions of years. Some experts identify four eons. (Example: Life on earth has been abundant during the Phanerozoic Eon, as well- preserved fossils prove.) Era: Shorter than an eon. -
Cretaceous - Tertiary Mass Extinction Meteoritic Versus Volcanic Causes
GENERAL I ARTICLE Cretaceous - Tertiary Mass Extinction Meteoritic Versus Volcanic Causes P V Sukumaran The bolide impact theory for mass extinctions at the Cretaceous-tertiary (K-T) boundary was a revolutionary concept. This theory was contested by short duration global volcanism as a possible alternative cause for the K-T extinction. Though there is a converging evidence for an extra-terrestrial impact coinciding with the P V Sukumaran took his terminal Cretaceous, the causative link between the M Tech degree in impact and the K-T mass extinction is debatable. Thus, Applied Geology from the while the impact theory is re-emerging, available evidence University of Saugar and has been with the is still insufficient to rule out either of the two hypotheses. Geological Survey of India since 1974. His interests Introduction include geochemistry, petrology and palae oceanography. He is It is now widely believed that life on earth began very early in presently posted to the its geological history, probably about 4000 My (million years) Marine Wing of the ago (Mojzsis and others, 1996). Since then it underwent Department and has participated in many several evolutionary branchings to the complex diversity as scientific cruises both as we see today. Nevertheless, it was not a smooth voyage for life Chief Scientist and as a all along, the evolution was punctuated by geologically participating scientist. ins tan taneous events of mass mortality. New species emerged at the expense of their predecessors following each extinction event and life went on evolving ever more vibrantly. In the geologic record of rock strata, such mass extinction events are identifiable based on sudden absence and reduction in diversity of fossil assemblage across stratigraphic boundaries. -
Crustacea: Thalassinidea, Brachyura) from Puerto Rico, United States Territory
Bulletin of the Mizunami Fossil Museum, no. 34 (2008), p. 1–15, 6 figs., 1 table. © 2008, Mizunami Fossil Museum New Cretaceous and Cenozoic Decapoda (Crustacea: Thalassinidea, Brachyura) from Puerto Rico, United States Territory Carrie E. Schweitzer1, Jorge Velez-Juarbe2, Michael Martinez3, Angela Collmar Hull1, 4, Rodney M. Feldmann4, and Hernan Santos2 1)Department of Geology, Kent State University Stark Campus, 6000 Frank Ave. NW, North Canton, Ohio, 44720, USA <[email protected]> 2)Department of Geology, University of Puerto Rico, Mayagüez Campus, P. O. Box 9017, Mayagüez, Puerto Rico, 00681 United States Territory <[email protected]> 3)College of Marine Science, University of South Florida, 140 7th Ave. South, St. Petersburg, Florida 33701, USA <[email protected]> 4)Department of Geology, Kent State University, Kent, Ohio 44242, USA <[email protected]> Abstract A large number of recently collected specimens from Puerto Rico has yielded two new species including Palaeoxanthopsis tylotus and Eurytium granulosum, the oldest known occurrence of the latter genus. Cretaceous decapods are reported from Puerto Rico for the first time, and the Cretaceous fauna is similar to that of southern Mexico. Herein is included the first report of Pleistocene decapods from Puerto Rico, which were previously known from other Caribbean localities. The Pleistocene Cardisoma guanhumi is a freshwater crab of the family Gecarcinidae. The freshwater crab families have a poor fossil record; thus, the occurrence is noteworthy and may document dispersal of the crab by humans. Key words: Decapoda, Thalassinidea, Brachyura, Puerto Rico, Cretaceous, Paleogene, Neogene. Introduction than Eocene are not separated by these fault zones and even overlie parts of the fault zones in some areas (Jolly et al., 1998). -
The Late Jurassic Tithonian, a Greenhouse Phase in the Middle Jurassic–Early Cretaceous ‘Cool’ Mode: Evidence from the Cyclic Adriatic Platform, Croatia
Sedimentology (2007) 54, 317–337 doi: 10.1111/j.1365-3091.2006.00837.x The Late Jurassic Tithonian, a greenhouse phase in the Middle Jurassic–Early Cretaceous ‘cool’ mode: evidence from the cyclic Adriatic Platform, Croatia ANTUN HUSINEC* and J. FRED READ *Croatian Geological Survey, Sachsova 2, HR-10000 Zagreb, Croatia Department of Geosciences, Virginia Tech, 4044 Derring Hall, Blacksburg, VA 24061, USA (E-mail: [email protected]) ABSTRACT Well-exposed Mesozoic sections of the Bahama-like Adriatic Platform along the Dalmatian coast (southern Croatia) reveal the detailed stacking patterns of cyclic facies within the rapidly subsiding Late Jurassic (Tithonian) shallow platform-interior (over 750 m thick, ca 5–6 Myr duration). Facies within parasequences include dasyclad-oncoid mudstone-wackestone-floatstone and skeletal-peloid wackestone-packstone (shallow lagoon), intraclast-peloid packstone and grainstone (shoal), radial-ooid grainstone (hypersaline shallow subtidal/intertidal shoals and ponds), lime mudstone (restricted lagoon), fenestral carbonates and microbial laminites (tidal flat). Parasequences in the overall transgressive Lower Tithonian sections are 1– 4Æ5 m thick, and dominated by subtidal facies, some of which are capped by very shallow-water grainstone-packstone or restricted lime mudstone; laminated tidal caps become common only towards the interior of the platform. Parasequences in the regressive Upper Tithonian are dominated by peritidal facies with distinctive basal oolite units and well-developed laminate caps. Maximum water depths of facies within parasequences (estimated from stratigraphic distance of the facies to the base of the tidal flat units capping parasequences) were generally <4 m, and facies show strongly overlapping depth ranges suggesting facies mosaics. Parasequences were formed by precessional (20 kyr) orbital forcing and form parasequence sets of 100 and 400 kyr eccentricity bundles. -
Gondwana Vertebrate Faunas of India: Their Diversity and Intercontinental Relationships
438 Article 438 by Saswati Bandyopadhyay1* and Sanghamitra Ray2 Gondwana Vertebrate Faunas of India: Their Diversity and Intercontinental Relationships 1Geological Studies Unit, Indian Statistical Institute, 203 B. T. Road, Kolkata 700108, India; email: [email protected] 2Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur 721302, India; email: [email protected] *Corresponding author (Received : 23/12/2018; Revised accepted : 11/09/2019) https://doi.org/10.18814/epiiugs/2020/020028 The twelve Gondwanan stratigraphic horizons of many extant lineages, producing highly diverse terrestrial vertebrates India have yielded varied vertebrate fossils. The oldest in the vacant niches created throughout the world due to the end- Permian extinction event. Diapsids diversified rapidly by the Middle fossil record is the Endothiodon-dominated multitaxic Triassic in to many communities of continental tetrapods, whereas Kundaram fauna, which correlates the Kundaram the non-mammalian synapsids became a minor components for the Formation with several other coeval Late Permian remainder of the Mesozoic Era. The Gondwana basins of peninsular horizons of South Africa, Zambia, Tanzania, India (Fig. 1A) aptly exemplify the diverse vertebrate faunas found Mozambique, Malawi, Madagascar and Brazil. The from the Late Palaeozoic and Mesozoic. During the last few decades much emphasis was given on explorations and excavations of Permian-Triassic transition in India is marked by vertebrate fossils in these basins which have yielded many new fossil distinct taxonomic shift and faunal characteristics and vertebrates, significant both in numbers and diversity of genera, and represented by small-sized holdover fauna of the providing information on their taphonomy, taxonomy, phylogeny, Early Triassic Panchet and Kamthi fauna. -
A Fundamental Precambrian–Phanerozoic Shift in Earth's Glacial
Tectonophysics 375 (2003) 353–385 www.elsevier.com/locate/tecto A fundamental Precambrian–Phanerozoic shift in earth’s glacial style? D.A.D. Evans* Department of Geology and Geophysics, Yale University, P.O. Box 208109, 210 Whitney Avenue, New Haven, CT 06520-8109, USA Received 24 May 2002; received in revised form 25 March 2003; accepted 5 June 2003 Abstract It has recently been found that Neoproterozoic glaciogenic sediments were deposited mainly at low paleolatitudes, in marked qualitative contrast to their Pleistocene counterparts. Several competing models vie for explanation of this unusual paleoclimatic record, most notably the high-obliquity hypothesis and varying degrees of the snowball Earth scenario. The present study quantitatively compiles the global distributions of Miocene–Pleistocene glaciogenic deposits and paleomagnetically derived paleolatitudes for Late Devonian–Permian, Ordovician–Silurian, Neoproterozoic, and Paleoproterozoic glaciogenic rocks. Whereas high depositional latitudes dominate all Phanerozoic ice ages, exclusively low paleolatitudes characterize both of the major Precambrian glacial epochs. Transition between these modes occurred within a 100-My interval, precisely coeval with the Neoproterozoic–Cambrian ‘‘explosion’’ of metazoan diversity. Glaciation is much more common since 750 Ma than in the preceding sedimentary record, an observation that cannot be ascribed merely to preservation. These patterns suggest an overall cooling of Earth’s longterm climate, superimposed by developing regulatory feedbacks