DOCSLIB.ORG

The Cambrian Explosion - 550-544 Ma ?

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Cambrian Explosion - 550-544 Ma ? Milestones in the first 3 billion years of life • Origin of life - before 3.8 Ga • Origin of eukaryotes - before 1.4 Ga; before 2.7 Ga ? • Origin of animals (multicellularity) - 600-800 Ma ? • Origin of skeletons - 550 Ma ? • The Cambrian Explosion - 550-544 Ma ? The Cambrian Explosion The relatively sudden appearance and diversification of almost all of the phyla (all but Bryozoa) in the early Cambrian. This event began around 550 million years ago and lasted no more than 20-30 million years. 1 Key Faunas Before/After the Cambrian Explosion: • Burgess Shale (505 Ma) • Chengjiang (520 Ma) • Small Shellies (Manykaian Stage) (544-530 Ma) • Doushantuo embryos (580-570 Ma) • Ediacara (575-545 Ma) The Ediacara Biota 2 The Ediacara Biota Parvancorina Dickensonia Cyclomedusa Tribrachidium Mawsonite s The Ediacara Biota Spriggina Charnia 3 Spaniard's Bay in eastern Newfoundland. 4 The “traditional” interpretation of Ediacara (from Glaessner (1984) Ediacara fronds: Comparison with living Pennatulacean Cnidarians 5 “Traditional” reconstructions of the Ediacara Biota A radical alternative interpretation of the Ediacara Biota: Vendobionta (From Seilacher, 1989) 6 A Chordate in the Ediacara?? (2003) Length ca. 5 cm) The latest on Ediacara… Nov. 2003 • There may be actual bilaterians among the Ediacaran biota • There are at least 3 biostratigraphically recognizeable assemblages: – Avalon 575-565 (e.g., Mistaken Point, Newfoundland) – Nama 565-550 – White Sea 550-545 7 The Ediacara Biota at Mistaken Point, Newfoundland http://geol.queensu.ca/museum/exhibits/ediac/mistaken_point/mistaken_pt.html Key Faunas Before/After the Cambrian Explosion: • Burgess Shale (505 Ma) • Chengjiang (520 Ma) • Small Shellies (Manykaian Stage) (544-530 Ma) • Doushantuo embryos (580-570 Ma) • Ediacara (575-545 Ma) 8 Doushantuo embryos http://more.abcnews.go.com/sections/science/DailyNews/fossils0204.html Bengtson & Zhao 1997, a SEM image depicting a suggested metazoan embryo – possibly Olivooides multisulcatus – at approximately the 256-cell stage. The Cambrian-Precambrian Boundary Treptichnus pedum 9 Key Faunas Before/After the Cambrian Explosion: • Burgess Shale (505 Ma) • Chengjiang (520 Ma) • Small Shellies (Manykaian Stage) (544-530 Ma) • Doushantuo embryos (580-570 Ma) • Ediacara (610-530+? Ma) Small Shellies 10 Small Shellies Small Shellies 11 The Tommotian fauna is a small shelly fauna found first on the Siberian Platform. The scale bars are all 1 millimetre. Photo: S. Bengston, in Evolution of the Earth, 1994 edition. What are small shellies? Halkieria, Sirius Passet, Greenland 12 Lapworthella www.palaeos.com/Invertebrates/ Procoelomates/Lapworthella.gi Key Faunas Before/After the Cambrian Explosion: • Burgess Shale (505 Ma) • Chengjiang (520 Ma) • Small Shellies (Manykaian Stage) (544-530 Ma) • Doushantuo embryos (580-570 Ma) • Ediacara (575-545 Ma) 13 The Chengjiang Fauna The Chengjiang fossil lagerstätte: Major outcrop in the Qiongzhusi Formation near Chengjiang, Yunnan Province. (c) 1997 by E. Landing 14 Microdictyon – an onychophoran Waptia – an arthropod 15 Canadaspis – an arthropod Hallucigenia – an onychophoran 16 Anomalocaris – a (very large) arthropod Naraoia – a trilobite 17 Cindarella Saperion 18 Fuxianhuia – an arthropod Yunnanozoon - the oldest known chordate 19 Haikouella – The oldest known vertebrate?? 20 Science, February 2003 Key Faunas Before/After the Cambrian Explosion: • Burgess Shale (505 Ma) • Chengjiang (520 Ma) • Small Shellies (Manykaian Stage) (544-530 Ma) • Doushantuo embryos (580-570 Ma) • Ediacara (610-530+? Ma) 21 Factoids about the Burgess Shale • Discovered in 1909 by C.D. Walcott • Middle Cambrian age • Walcott did not think the Burgess creatures were that remarkable • Restudy in the 1980s showed that many Burgess taxa were very unusual • Best-selling 1989 book by S.J. Gould made Burgess famous and encouraged more study • Burgess and Chengjiang share many taxa (1989) 22 The Burgess Shale Charles Walcott 23 Wiwaxia - a mollusk? 24 Aysheaia - an onychophoran A modern onychophoran 25 New reconstruction ⇑ ⇐ Old reconstruction Hallucigenia – an onychophoran Thamnauptilon – a penatulacean (sea pen) 26 Pikaia - a chordate Opabinia – affinities unknown 27 Reconstructions of Opabinia Marella – an arthropod 28 Anomalocaris – an arthropod Anomalocaris 29 Anomalocaris 30 Reconstruction of the Burgess Shale fauna www.emc.maricopa.edu/faculty/ farabee/BIOBK/1ord04b.gif 31 Evidence of predation in the Burgess Shale Temporal distribution of Burgess-type faunas 32 How might all this fit together? • The fossils • Snowball Earth • Molecular clocks • Developmental genetics How might all this fit together? • The fossils • The environment: Snowball Earth • Molecular clocks • Developmental genetics 33 How might all these faunas fit together? The fossils. • If there were animals before Ediacara, they were small • Ediacara mostly soft-bodied; many did not leave decendants; some did • Skeletons appeared abruptly at the boundary • Many early skeletonized animals had multi- element skeletons • The “explosion” was truly sudden (a few million years) and produced almost all the phyla 34 Halkieria, Sirius Passet, Greenland Similarities between Wiwaxia and Halkieria Halkieria Wiwaxia 35 36 How might all this fit together? • The fossils • The environment: Snowball Earth • Molecular clocks • Developmental genetics Late Proterozoic Environmental Changes • Major glaciations • Major carbon burial events 37 Late Proterozoic Glaciations Duoshantuo? • ≈ 580 Ma - Gaskiers Glaciation Duoshantuo? • ≈ 680 Ma - Marinoan Glaciation • ≈ 710 Ma - Stirtian Glaciation 38 Snowball Earth Stage 1: Prologue Stage 3: Snowball as it Thaws Stage 2: Snowball Earth at Its Coldest Stage 4: Hothouse Aftermath 39 How might all this fit together? • The fossils • The environment: Snowball Earth • Molecular clocks • Developmental genetics 40 (from Bromham & Hendy, Proc. R. Soc. Lond., 2000, 267:1041) How might all this fit together? • The fossils • The environment: Snowball Earth • Molecular clocks • Developmental genetics 41 The role of development Recent discoveries in developmental biology tell us that it is possible for major evolutionary changes in morphology to occur abruptly through relatively small genetic changes. Phylogeny of the Burgess/Chengjiang arthropods From Bioessays 19, pg 431. Fortey R.A., et al, 1997. 42 The Cambrian Explosion: An attempt at synthesis • One Possible Scenario: The phyla originated sometime in the late Proterozoic (1000-600 Ma), but remained small during environmental changes associated with major late Proterozoic glaciations (which may have reached the level of “snowball earth”). These environmental changes -- combined with one or more major genetic/developmental changes -- led to the Cambrian Explosion. 43.
Load more

Recommended publications
  • A New Species of Yunnanozoan with Implications for Deuterostome
    R EPORTS istry, K. S. Birdi, Ed. (CRC Press Inc., Boca Raton, FL, 23. L. H. Sperling, Polymeric Multicomponent Materials (grant EA/TU¨ BA-GEBI˙P/2001-1-1) and the Koc¸ Uni- 1997),࿜࿜࿜࿜ chap. 9. (Wiley-Interscience, New York, 1997), chap. 6. versity Fiat Fund. 18. , G. McHale, M. I. Newton, Langmuir 18, 2636 24. J. Varga, in Polypropylene Structure, Blends and Com- Supporting Online Material (2002). posites, J. Karger-Kocsis, Ed. (Chapman and Hall, Lon- www.sciencemag.org/cgi/content/full/299/5611/1377/ 19. Materials and methods are available as supporting don, 1995), vol. 1, chap. 3. DC1 material on Science Online. 25. We thank A. Altay, M. A. Gu¨lgu¨n of Sabancı Univer- Materials and Methods 20. R. N. Wenzel, Ind. Eng. Chem. 28, 988 (1936). sity, and A. Alkan of Brisa for their help with SEM Figs. S1 and S2 21. A. B. D. Cassie, S. Baxter, Trans. Faraday Soc. 3, 16 (1944). measurements. A.L.D. acknowledges the financial References 22. R. A. Veselovsky, V. N. Kestelman, Adhesion of Poly- support of the Turkish Academy of Sciences in the mers (McGraw-Hill, New York, 2002), chap. 2. framework of the Young Scientist Award Program 11 September 2002; accepted 22 January 2003 and ventral units are rarely touching (Fig. 1, A New Species of Yunnanozoan G and H), suggesting that the entire anterior region could expand and contract in height. with Implications for The expansion would occur by an accommo- dation along the median zone and about an axis of rotation near the posterior of the units.
    [Show full text]
  • Early Fossil Record of Euarthropoda and the Cambrian Explosion
    PERSPECTIVE Early fossil record of Euarthropoda and the Cambrian Explosion PERSPECTIVE Allison C. Daleya,b,c,1, Jonathan B. Antcliffea,b,c, Harriet B. Dragea,b,c, and Stephen Patesa,b Edited by Neil H. Shubin, University of Chicago, Chicago, IL, and approved April 6, 2018 (received for review December 20, 2017) Euarthropoda is one of the best-preserved fossil animal groups and has been the most diverse animal phylum for over 500 million years. Fossil Konservat-Lagerstätten, such as Burgess Shale-type deposits (BSTs), show the evolution of the euarthropod stem lineage during the Cambrian from 518 million years ago (Ma). The stem lineage includes nonbiomineralized groups, such as Radiodonta (e.g., Anomalocaris) that provide insight into the step-by-step construction of euarthropod morphology, including the exo- skeleton, biramous limbs, segmentation, and cephalic structures. Trilobites are crown group euarthropods that appear in the fossil record at 521 Ma, before the stem lineage fossils, implying a ghost lineage that needs to be constrained. These constraints come from the trace fossil record, which show the first evi- dence for total group Euarthropoda (e.g., Cruziana, Rusophycus) at around 537 Ma. A deep Precambrian root to the euarthropod evolutionary lineage is disproven by a comparison of Ediacaran and Cambrian lagerstätten. BSTs from the latest Ediacaran Period (e.g., Miaohe biota, 550 Ma) are abundantly fossilif- erous with algae but completely lack animals, which are also missing from other Ediacaran windows, such as phosphate deposits (e.g., Doushantuo, 560 Ma). This constrains the appearance of the euarthropod stem lineage to no older than 550 Ma.
    [Show full text]
  • Ediacaran) of Earth – Nature’S Experiments
    The Early Animals (Ediacaran) of Earth – Nature’s Experiments Donald Baumgartner Medical Entomologist, Biologist, and Fossil Enthusiast Presentation before Chicago Rocks and Mineral Society May 10, 2014 Illinois Famous for Pennsylvanian Fossils 3 In the Beginning: The Big Bang . Earth formed 4.6 billion years ago Fossil Record Order 95% of higher taxa: Random plant divisions domains & kingdoms Cambrian Atdabanian Fauna Vendian Tommotian Fauna Ediacaran Fauna protists Proterozoic algae McConnell (Baptist)College Pre C - Fossil Order Archaean bacteria Source: Truett Kurt Wise The First Cells . 3.8 billion years ago, oxygen levels in atmosphere and seas were low • Early prokaryotic cells probably were anaerobic • Stromatolites . Divergence separated bacteria from ancestors of archaeans and eukaryotes Stromatolites Dominated the Earth Stromatolites of cyanobacteria ruled the Earth from 3.8 b.y. to 600 m. [2.5 b.y.]. Believed that Earth glaciations are correlated with great demise of stromatolites world-wide. 8 The Oxygen Atmosphere . Cyanobacteria evolved an oxygen-releasing, noncyclic pathway of photosynthesis • Changed Earth’s atmosphere . Increased oxygen favored aerobic respiration Early Multi-Cellular Life Was Born Eosphaera & Kakabekia at 2 b.y in Canada Gunflint Chert 11 Earliest Multi-Cellular Metazoan Life (1) Alga Eukaryote Grypania of MI at 1.85 b.y. MI fossil outcrop 12 Earliest Multi-Cellular Metazoan Life (2) Beads Horodyskia of MT and Aust. at 1.5 b.y. thought to be algae 13 Source: Fedonkin et al. 2007 Rise of Animals Tappania Fungus at 1.5 b.y Described now from China, Russia, Canada, India, & Australia 14 Earliest Multi-Cellular Metazoan Animals (3) Worm-like Parmia of N.E.
    [Show full text]
  • Fossil Invertebrates of the Phanerozoic
    The Origin of Phyla and the Cambrian Explosion of Life Geology 230 Fossils and Evolution Cambrian Life • The first animals evolved about 60 my before the start of the Cambrian. These are the Ediacaran fossils of the latest Proterozoic. • None of these animals had hard parts. • Base of the Cambrian defined by first animals with hard parts. Life at the end of the Proterozoic Life at the end of the Proterozoic Cambrian Life • Early Cambrian fossils consist mostly of small little shells that are later followed by trilobites and brachiopods. Small little shells: sclerites on soft-bodied animals Cambrian trilobites cruising on Saturday night Typical Cambrian trilobites Modern horseshoe crabs look similar to trilobites, but they are not closely related. Example of a “living fossil.” Trilobites are extinct. A living Inarticulate Brachiopod. Very common in the Cambrian. Modern Inarticulate Brachiopods in their burrows Modern Inarticulate Brachiopods for dinner The Cambrian “Explosion” of Life • What is the Cambrian “Explosion”? • Is it a true explosion of phyla, or was there a “slow fuse” back into the Proterozoic? • Why did so many new phyla appear at this time? Hox genes hold the answer. • Why have no new phyla appeared since this time? MicroRNA holds the answer. The Tree of Life www.evogeneao.com/tree.html Cambrian Explosion, radiation of triploblasts (3 tissue layers) Diploblasts (2 tissue layers) Diploblastic Animals: Triploblastic Animals: Two Tissue Layers Three Tissue Layers Mesoderm in blue (jelly) Deuterostomes (mouth is second opening during development) Protostomes (mouth is first opening during development) Ecdysozoa Lophotrochozoa Protostomes (mouth is first opening during development) Deuterostomes (mouth is second opening during development) Prothero, 2007 Prothero, 2007 Hox genes determine the head to tail anatomy of animals.
    [Show full text]
  • Gehling-Ediacaran Publications 2015 Palaeo Down Under2
    Gehling-Ediacaran Publications 2015 1. Droser, M.L. and Gehling, J.G. 2015. The advent of animals: the view from the Ediacaran: Proceedings of the National Academy of Sciences 112, 4865-4870. 2. Evans, S.D., Droser, M.L. and Gehling, J.G. 2015. Dickinsonia lift off: Evidence of current derived morphologies. Palaeogeography Palaeoclimatology Palaeoecology ; DOI: 10.1016/j.palaeo.2015.02.006. 3. Hall, C.M.S., Droser, M.L., Gehling, J.G., Dzaugis. M.E. 2015. Paleoecology of the enigmatic Tribrachidium: New data from the Ediacaran of South Australia. Precambrian Research 269:183-194. 4. Gold, D. A., Runnegar, B., Gehling, J.G., and Jacobs, D.K. 2015. Ancestral state reconstruction of ontogeny supports a bilaterian affinity for Dickinsonia. Evolution and Development 17 (6), 315–397. 5. Tarhan, L.G., Droser, M.L. and Gehling, J.G. 2015. Taphonomy and morphology of the Ediacara form genus Aspidella. Precambrian Research 257:124-136. 6. Tarhan, L.G., Droser, M.L. and Gehling, J.G. 2015. Depositional and preservational environments of the Ediacara Member, Rawnsley Quartzite (South Australia): Assessment of paleoenvironmental proxies and the timing of ‘ferruginization’. Palaeogeography, Palaeclimatology, Paleoecology in press. Palaeo Down Under2 — July 2016 Association of Australasian Palaeontologists (AAP) is organizing a Palaeo Down Under 2 conference at the University of Adelaide in South Australia from July 10-15. The conference is preceded by a Field Excursion to key Cambrian localities of Kangaroo Island, the Fleurieu Peninsula and the Cambrian and Ediacaran of the Flinders Ranges from July 3-9. Ediacara Research — South Australia 2015 Ediacara research in South Australia has continued with further excavations at the National Heritage Listed Ediacara Fossil Site at Nilpena, a new site in the northern Flinders Ranges of South Australia, and for the first time, at the historic discovery site in the Ediacara Conservation Park.
    [Show full text]
  • The Cambrian Explosion: a Big Bang in the Evolution of Animals
    The Cambrian Explosion A Big Bang in the Evolution of Animals Very suddenly, and at about the same horizon the world over, life showed up in the rocks with a bang. For most of Earth’s early history, there simply was no fossil record. Only recently have we come to discover otherwise: Life is virtually as old as the planet itself, and even the most ancient sedimentary rocks have yielded fossilized remains of primitive forms of life. NILES ELDREDGE, LIFE PULSE, EPISODES FROM THE STORY OF THE FOSSIL RECORD The Cambrian Explosion: A Big Bang in the Evolution of Animals Our home planet coalesced into a sphere about four-and-a-half-billion years ago, acquired water and carbon about four billion years ago, and less than a billion years later, according to microscopic fossils, organic cells began to show up in that inert matter. Single-celled life had begun. Single cells dominated life on the planet for billions of years before multicellular animals appeared. Fossils from 635,000 million years ago reveal fats that today are only produced by sponges. These biomarkers may be the earliest evidence of multi-cellular animals. Soon after we can see the shadowy impressions of more complex fans and jellies and things with no names that show that animal life was in an experimental phase (called the Ediacran period). Then suddenly, in the relatively short span of about twenty million years (given the usual pace of geologic time), life exploded in a radiation of abundance and diversity that contained the body plans of almost all the animals we know today.
    [Show full text]
  • The Evolution of Trilobite Body Patterning
    ANRV309-EA35-14 ARI 20 March 2007 15:54 The Evolution of Trilobite Body Patterning Nigel C. Hughes Department of Earth Sciences, University of California, Riverside, California 92521; email: [email protected] Annu. Rev. Earth Planet. Sci. 2007. 35:401–34 Key Words First published online as a Review in Advance on Trilobita, trilobitomorph, segmentation, Cambrian, Ordovician, January 29, 2007 diversification, body plan The Annual Review of Earth and Planetary Sciences is online at earth.annualreviews.org Abstract This article’s doi: The good fossil record of trilobite exoskeletal anatomy and on- 10.1146/annurev.earth.35.031306.140258 togeny, coupled with information on their nonbiomineralized tis- Copyright c 2007 by Annual Reviews. sues, permits analysis of how the trilobite body was organized and All rights reserved developed, and the various evolutionary modifications of such pat- 0084-6597/07/0530-0401$20.00 terning within the group. In several respects trilobite development and form appears comparable with that which may have charac- terized the ancestor of most or all euarthropods, giving studies of trilobite body organization special relevance in the light of recent advances in the understanding of arthropod evolution and devel- opment. The Cambrian diversification of trilobites displayed mod- Annu. Rev. Earth Planet. Sci. 2007.35:401-434. Downloaded from arjournals.annualreviews.org ifications in the patterning of the trunk region comparable with by UNIVERSITY OF CALIFORNIA - RIVERSIDE LIBRARY on 05/02/07. For personal use only. those seen among the closest relatives of Trilobita. In contrast, the Ordovician diversification of trilobites, although contributing greatly to the overall diversity within the clade, did so within a nar- rower range of trunk conditions.
    [Show full text]
  • Soft Anatomy of the Early Cambrian Arthropod Isoxys Curvirostratus from the Chengjiang Biota of South China with a Discussion on the Origination of Great Appendages
    Soft anatomy of the Early Cambrian arthropod Isoxys curvirostratus from the Chengjiang biota of South China with a discussion on the origination of great appendages DONG−JING FU, XING−LIANG ZHANG, and DE−GAN SHU Fu, D.−J., Zhang, X.−L., and Shu, D.−G. 2011. Soft anatomy of the Early Cambrian arthropod Isoxys curvirostratus from the Chengjiang biota of South China with a discussion on the origination of great appendages. Acta Palaeontologica Polonica 56 (4): 843–852. An updated reconstruction of the body plan, functional morphology and lifestyle of the arthropod Isoxys curvirostratus is proposed, based on new fossil specimens with preserved soft anatomy found in several localities of the Lower Cambrian Chengjiang Lagerstätte. The animal was 2–4 cm long and mostly encased in a single carapace which is folded dorsally without an articulated hinge. The attachment of the body to the exoskeleton was probably cephalic and apparently lacked any well−developed adductor muscle system. Large stalked eyes with the eye sphere consisting of two layers (as corneal and rhabdomeric structures) protrude beyond the anterior margin of the carapace. This feature, together with a pair of frontal appendages with five podomeres that each bear a stout spiny outgrowth, suggests it was raptorial. The following 14 pairs of limbs are biramous and uniform in shape. The slim endopod is composed of more than 7 podomeres without terminal claw and the paddle shaped exopod is fringed with at least 17 imbricated gill lamellae along its posterior margin. The design of exopod in association with the inner vascular (respiratory) surface of the carapace indicates I.
    [Show full text]
  • 29 | Vertebrates 791 29 | VERTEBRATES
    Chapter 29 | Vertebrates 791 29 | VERTEBRATES Figure 29.1 Examples of critically endangered vertebrate species include (a) the Siberian tiger (Panthera tigris), (b) the mountain gorilla (Gorilla beringei), and (c) the Philippine eagle (Pithecophega jefferyi). (credit a: modification of work by Dave Pape; credit b: modification of work by Dave Proffer; credit c: modification of work by "cuatrok77"/Flickr) Chapter Outline 29.1: Chordates 29.2: Fishes 29.3: AmphiBians 29.4: Reptiles 29.5: Birds 29.6: Mammals 29.7: The Evolution of Primates Introduction Vertebrates are among the most recognizable organisms of the animal kingdom. More than 62,000 vertebrate species have been identified. The vertebrate species now living represent only a small portion of the vertebrates that have existed. The best-known extinct vertebrates are the dinosaurs, a unique group of reptiles, which reached sizes not seen before or after in terrestrial animals. They were the dominant terrestrial animals for 150 million years, until they died out in a mass extinction near the end of the Cretaceous period. Although it is not known with certainty what caused their extinction, a great deal is known about the anatomy of the dinosaurs, given the preservation of skeletal elements in the fossil record. Currently, a number of vertebrate species face extinction primarily due to habitat loss and pollution. According to the International Union for the Conservation of Nature, more than 6,000 vertebrate species are classified as threatened. Amphibians and mammals are the classes with the greatest percentage of threatened species, with 29 percent of all amphibians and 21 percent of all mammals classified as threatened.
    [Show full text]
  • 2 the Evolutionary Significance of the Chengjiang Biota
    The Cambrian Fossils of Chengjiang, China The Flowering of Early Animal Life The Cambrian Fossils of Chengjiang, China The Flowering of Early Animal Life Second Edition Hou Xian-guang, David J. Siveter, Derek J. Siveter, Richard J. Aldridge, Cong Pei-yun, Sarah E. Gabbott, Ma Xiao-ya, Mark A. Purnell, Mark Williams This edition first published 2017 © 2017 by John Wiley & Sons Ltd. First edition published 2004 © 2004 by Blackwell Science Ltd. Registered Office John Wiley & Sons Ltd., The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK Editorial Offices 9600 Garsington Road, Oxford, OX4 2DQ, UK The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK 111 River Street, Hoboken, NJ 07030‐5774, USA For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book, please see our website at www.wiley.com/wiley‐blackwell. The right of the author to be identified as the author of this work has been asserted in accordance with the UK Copyright, Designs and Patents Act 1988. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners.
    [Show full text]
  • The Secrets of Fossils Lesson by Tucker Hirsch
    The Secrets of Fossils Lesson by Tucker Hirsch Video Titles: Introduction: A New view of the Evolution of Animals Cambrian Explosion Jenny Clack, Paleontologist: The First Vertebrate Walks on Land Des Collins, Paleontologist: The Burgess Shale Activity Subject: Assessing evolutionary links NEXT GENERATION SCIENCE STANDARDS and evidence from comparative analysis of the fossil MS-LS4-1 Analyze and interpret data for patterns record and modern day organisms. in the fossil record that document the existence, diversity, extinction, and change of life forms Grade Level: 6 – 8 grades throughout the history of life on Earth under the Introduction assumptions that natural laws operate today as In this lesson students make connections between in the past. [Clarification Statement: Emphasis fossils and modern day organisms. Using the is on finding patterns of changes in the level of information about the Cambrian Explosion, they complexity of anatomical structures in organisms explore theories about how and why organisms diversified. Students hypothesize what evidence and the chronological order of fossil appearance might be helpful to connect fossil organisms to in the rock layers.] [Assessment Boundary: modern organisms to show evolutionary connections. Assessment does not include the names of Students use three videos from shapeoflife.org. individual species or geological eras in the fossil record.] Assessments Written MS-LS4-2 Apply scientific ideas to construct an Time 100-120 minutes (2 class periods) explanation for the anatomical similarities and Group Size Varies; single student, student pairs, differences among modern organisms and between entire class modern and fossil organisms to infer evolutionary relationships. [Clarification Statement: Emphasis Materials and Preparation is on explanations of the evolutionary relationships • Access to the Internet to watch 4 Shape of Life videos among organisms in terms of similarity or • Video Worksheet differences of the gross appearance of anatomical • “Ancient-Modern” Activity.
    [Show full text]
  • J32 the Importance of the Burgess Shale < Soft Bodied Fauna >
    580 Chapter j PALEOCONTINENTS The Present is the Key to the Past: HUGH RANCE j32 The importance of the Burgess shale < soft bodied fauna > Only about 33 animal body plans are presently [sic] being used on this planet (Margulis and Schwartz, 1988). —Scott F. Gilbert, Developmental Biology, 1991.1 Almost all animal phyla known today were already present by 505 million years ago— the age of the Burgess shale, Middle Cambrian marine sediments, discovered at the Kicking Horse rim, British Columbia, in 1909 by Charles Doolittle Walcott, that provide a unique window on life without hard parts that had continued to exist shortly after the time of the Cambrian explosion (see Topic j34).2 Legend has it that Walcott, then secretary of the Smithsonian Institution, vacationing near Field, British Columbia, was thrown from a horse carrying him, when it tripped on, and split open a stray fallen slab of shale. Walcott, with his face literally rubbed in it, saw strange, but not hallucinational, forms crisply etched in black against the blue-black bedding surface of the shale: a bonanza of fossils of sea creatures without mineralized shells or backbones. Many are preserved whole; including those with articulated organic (biodegradable) exoskeletons. Details of even their soft body parts can be seen (best using PTM)3 as silvery films (formed of phyllosilicates on a coating of kerogenized carbon) that commonly outline even the most delicate structures on the fossilized animal.4 The Burgess shale is part of the Stephen Formation of greenish shales and thin-bedded limestones, which is a marine-offlap deposit between the thick, massive, carbonates of the overlying Eldon formation, and the underlying Cathedral formation.6 As referenced in the Geological Atlas of the Western Canada Sedimentary Basin - Chapter 8, the Stephen Formation has been “informally divided into a normal, ‘thin Stephen’ on the platform areas and a ‘thick Stephen’ west of the Cathedral Escarpment.
    [Show full text]