Ediacaran Extinction and Cambrian Explosion
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Discovery of Bilaterian-Type Through-Guts in Cloudinomorphs from the Terminal Ediacaran Period
ARTICLE https://doi.org/10.1038/s41467-019-13882-z OPEN Discovery of bilaterian-type through-guts in cloudinomorphs from the terminal Ediacaran Period James D. Schiffbauer 1,2*, Tara Selly 1,2*, Sarah M. Jacquet 1, Rachel A. Merz3, Lyle L. Nelson4, Michael A. Strange5, Yaoping Cai6 & Emily F. Smith 4 The fossil record of the terminal Ediacaran Period is typified by the iconic index fossil Cloudina and its relatives. These tube-dwellers are presumed to be primitive metazoans, but resolving 1234567890():,; their phylogenetic identity has remained a point of contention. The root of the problem is a lack of diagnostic features; that is, phylogenetic interpretations have largely centered on the only available source of information—their external tubes. Here, using tomographic analyses of fossils from the Wood Canyon Formation (Nevada, USA), we report evidence of recog- nizable soft tissues within their external tubes. Although alternative interpretations are plausible, these internal cylindrical structures may be most appropriately interpreted as digestive tracts, which would be, to date, the earliest-known occurrence of such features in the fossil record. If this interpretation is correct, their nature as one-way through-guts not only provides evidence for establishing these fossils as definitive bilaterians but also has implications for the long-debated phylogenetic position of the broader cloudinomorphs. 1 Department of Geological Sciences, University of Missouri, Columbia, MO 65211, USA. 2 X-ray Microanalysis Core, University of Missouri, Columbia, MO 65211, USA. 3 Biology Department, Swarthmore College, Swarthmore, PA 19081, USA. 4 Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218, USA. -
Stratigraphic Paleobiology of an Evolutionary Radiation: Taphonomy and Facies Distribution of Cetaceans in the Last 23 Million Years
Fossilia, Volume 2018: 15-17 Stratigraphic paleobiology of an evolutionary radiation: taphonomy and facies distribution of cetaceans in the last 23 million years Stefano Dominici1, Simone Cau2 & Alessandro Freschi2 1 Museo di Storia Naturale, Università degli Studi di Firenze, Firenze, Italy; [email protected] 2 Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale, Università degli Studi di Parma, Parma, Italy; cau.simo- [email protected], [email protected] BULLET-POINTS ABSTRACT KEYWORDS: • The majority of cetacean fossils are in Zanclean and Piacenzian deposits. Neogene; • Cetacean fossils are preferentially found in offshore paleosettings. Pliocene; • Pleistocene findings drop to a minimum, notwithstanding offshore strata are Cetaceans; well represented in the record. Taphonomy. • A taphonomic imprinting on the cetacean fossil record is hypothesised, con- nected with a radiation of whale-bone consumers of modern type. offer a particularly rich cetacean fossil record and an INTRODUCTION area where available studies allow to explore this key The study of the stratigraphy and taphonomy of Neo- time of cetacean evolution at a stratigraphic resolution gene cetaceans is a fundamental step to properly frame finer than the stage. An increase in cetaceans diversity the evolutionary radiation of this megafauna, at the is recorded around 3.2 – 3.0 Ma, in coincidence of top of the pelagic marine ecosystem. Major evolutio- the mid-Piacenzian climatic optimum, and a drastic nary steps have been summarised in recent -
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. -
Decoupled Evolution of Soft and Hard Substrate Communities During the Cambrian Explosion and Great Ordovician Biodiversification Event
Decoupled evolution of soft and hard substrate communities during the Cambrian Explosion and Great Ordovician Biodiversification Event Luis A. Buatoisa,1, Maria G. Mánganoa, Ricardo A. Oleab, and Mark A. Wilsonc aDepartment of Geological Sciences, University of Saskatchewan, Saskatoon, SK, Canada S7N 5E2; bEastern Energy Resources Science Center, US Geological Survey, Reston, VA 20192; and cDepartment of Geology, The College of Wooster, Wooster, OH 44691 Edited by Steven M. Holland, University of Georgia, Athens, GA, and accepted by Editorial Board Member David Jablonski May 6, 2016 (received for review November 21, 2015) Contrasts between the Cambrian Explosion (CE) and the Great shed light on the natures of both radiations. Because there is still Ordovician Biodiversification Event (GOBE) have long been recog- controversy regarding Sepkoski’s nonstandardized curves of nized. Whereas the vast majority of body plans were established Phanerozoic taxonomic diversity (13–15), a rarefaction analysis as a result of the CE, taxonomic increases during the GOBE were was performed in an attempt to standardize diversity data. The manifested at lower taxonomic levels. Assessing changes of ichno- aims of this paper are to document the contrasting ichnodiversity diversity and ichnodisparity as a result of these two evolutionary and ichnodisparity trajectories in soft and hard substrate com- events may shed light on the dynamics of both radiations. The early munities during these two evolutionary events and to discuss the Cambrian (series 1 and 2) displayed a dramatic increase in ichnodi- possible underlying causes of this decoupled evolution. versity and ichnodisparity in softground communities. In contrast to this evolutionary explosion in bioturbation structures, only a few Results Cambrian bioerosion structures are known. -
A Revised Morphology of Cloudina with Ecological and Phylogenetic Implications Andrew J
A Revised Morphology of Cloudina with Ecological and Phylogenetic Implications Andrew J. Miller Departments of Earth and Planetary Sciences and of History Harvard University, Cambridge, MA 02138 [email protected] Abstract The conventional view of the Ediacaran index fossil Cloudina, as proposed by Grant (1990), depicts the shell structure as a series of nested test tubes. A digital serial-reconstruction of Cloudina and examination of thin sections indicates that only the bottom-most tube has a bottom and that the shell wall structure is not as well defined as previously thought. The conventional ecological reconstruction, as proposed by Seilacher (1999), puts Cloudina in a microbial mat framework. Evidence from fossils in situ and from the shape of Cloudina suggests that this interpretation is incorrect. Rather, I propose that Cloudina lived on seaweeds in the reef environment. I also introduce a new mode of inference in determining shell orientation based on gravitational forces. Given the morphological evidence, Cloudina appears to be more similar to pogonophoran or annelid worms and less similar than previously thought to cnidarian corals. Introduction Life in the Precambrian is seen by many in a Hobbesian view—sessile, benthic, and short. While this may accurately describe the functional behavior of Ediacaran communities, it overlooks the significant metazoan diversity that was present there, for within the Ediacaran period the first metazoans entered the fossil record and diversified. Even though the presence of metazoans in the Ediacaran has been known for over thirty years, relatively little is known about their phylogenic affinities, their structure, and their role in the ecosystem. -
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. -
1 Revision 2 1 K-Bentonites
1 Revision 2 2 K-Bentonites: A Review 3 Warren D. Huff 4 Department of Geology, University of Cincinnati, Cincinnati, OH 45221 USA 5 Email: [email protected] 6 Keywords: K-bentonite, bentonite, tephra, explosive volcanism, volcanic ash 7 Abstract 8 Pyroclastic material in the form of altered volcanic ash or tephra has been reported and described 9 from one or more stratigraphic units from the Proterozoic to the Tertiary. This altered tephra, 10 variously called bentonite or K-bentonite or tonstein depending on the degree of alteration and 11 chemical composition, is often linked to large explosive volcanic eruptions that have occurred 12 repeatedly in the past. K-bentonite and bentonite layers are the key components of a larger group of 13 altered tephras that are useful for stratigraphic correlation and for interpreting the geodynamic 14 evolution of our planet. Bentonites generally form by diagenetic or hydrothermal alteration under 15 the influence of fluids with high Mg content and that leach alkali elements. Smectite composition is 16 partly controlled by parent rock chemistry. Studies have shown that K-bentonites often display 17 variations in layer charge and mixed-layer clay ratios and that these correlate with physical 18 properties and diagenetic history. The following is a review of known K-bentonite and related 19 occurrences of altered tephra throughout the time scale from Precambrian to Cenozoic. 20 Introduction 21 Volcanic eruptions are often, although by no means always, associated with a profuse output 22 of fine pyroclastic material, tephra. Tephra is a term used to describe all of the solid material 23 produced from a volcano during an eruption (Thorarinsson, 1944). -
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. -
Lessons from the Fossil Record: the Ediacaran Radiation, the Cambrian Radiation, and the End-Permian Mass Extinction
OUP CORRECTED PROOF – FINAL, 06/21/12, SPi CHAPTER 5 Lessons from the fossil record: the Ediacaran radiation, the Cambrian radiation, and the end-Permian mass extinction S tephen Q . D ornbos, M atthew E . C lapham, M argaret L . F raiser, and M arc L afl amme 5.1 Introduction and altering substrate consistency ( Thayer 1979 ; Seilacher and Pfl üger 1994 ). In addition, burrowing Ecologists studying modern communities and eco- organisms play a crucial role in modifying decom- systems are well aware of the relationship between position and enhancing nutrient cycling ( Solan et al. biodiversity and aspects of ecosystem functioning 2008 ). such as productivity (e.g. Tilman 1982 ; Rosenzweig Increased species richness often enhances ecosys- and Abramsky 1993 ; Mittelbach et al. 2001 ; Chase tem functioning, but a simple increase in diversity and Leibold 2002 ; Worm et al. 2002 ), but the pre- may not be the actual underlying driving mecha- dominant directionality of that relationship, nism; instead an increase in functional diversity, the whether biodiversity is a consequence of productiv- number of ecological roles present in a community, ity or vice versa, is a matter of debate ( Aarssen 1997 ; may be the proximal cause of enhanced functioning Tilman et al. 1997 ; Worm and Duffy 2003 ; van ( Tilman et al. 1997 ; Naeem 2002 ; Petchey and Gaston, Ruijven and Berendse 2005 ). Increased species rich- 2002 ). The relationship between species richness ness could result in increased productivity through (diversity) and functional diversity has important 1) interspecies facilitation and complementary implications for ecosystem functioning during resource use, 2) sampling effects such as a greater times of diversity loss, such as mass extinctions, chance of including a highly productive species in a because species with overlapping ecological roles diverse assemblage, or 3) a combination of biologi- can provide functional redundancy to maintain cal and stochastic factors ( Tilman et al. -
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. -
Geobiological Events in the Ediacaran Period
Geobiological Events in the Ediacaran Period Shuhai Xiao Department of Geosciences, Virginia Tech, Blacksburg, VA 24061, USA NSF; NASA; PRF; NSFC; Virginia Tech Geobiology Group; CAS; UNLV; UCR; ASU; UMD; Amherst; Subcommission of Neoproterozoic Stratigraphy; 1 Goals To review biological (e.g., acanthomorphic acritarchs; animals; rangeomorphs; biomineralizing animals), chemical (e.g., carbon and sulfur isotopes, oxygenation of deep oceans), and climatic (e.g., glaciations) events in the Ediacaran Period; To discuss integration and future directions in Ediacaran geobiology; 2 Knoll and Walter, 1992 • Acanthomorphic acritarchs in early and Ediacara fauna in late Ediacaran Period; • Strong carbon isotope variations; • Varanger-Laplandian glaciation; • What has happened since 1992? 3 Age Constraints: South China (538.2±1.5 Ma) 541 Ma Cambrian Dengying Ediacaran Sinian 551.1±0.7 Ma Doushantuo 632.5±0.5 Ma 635 Ma 635.2±0.6 Ma Nantuo (Tillite) 636 ± 5Ma Cryogenian Nanhuan 654 ± 4Ma Datangpo 663±4 Ma Neoproterozoic Neoproterozoic Jiangkou Group Banxi Group 725±10 Ma Tonian Qingbaikouan 1000 Ma • South China radiometric ages: Condon et al., 2005; Hoffmann et al., 2004; Zhou et al., 2004; Bowring et al., 2007; S. Zhang et al., 2008; Q. Zhang et al., 2008; • Additional ages from Nama Group (Namibia), Conception Group (Newfoundland), and Vendian (White Sea); 4 The Ediacaran Period Ediacara fossils Cambrian 545 Ma Nama assemblage 555 Ma White Sea assemblage 565 Ma Avalon assemblage 575 Ma 585 Ma Doushantuo biota 595 Ma 605 Ma Ediacaran Period 615 Ma -
Page - Paleo Lab 06 - the Cambrian Explosion of Life
page - Paleo Lab 06 - The Cambrian Explosion of Life An Introduction to Index Fossils CLASSIFICATION AND TAXONOMY Geologists follow the lead of biologists in the classification and naming of organisms (taxonomy after taxon = name). Since its introduction early in the 18th century, the system devised by Linnaeus has been used to categorize organisms and to affix a formal name to each species. Major classification categories or groupings are listed below on the left with an example using the species of the common house cat to show how the system may be used: KINGDOM Animalia PHYLUM Chordata CLASS Mammalia ORDER Carnivora FAMILY Felidae GENUS Felis SPECIES domestica The basic unit of the system is the species, and each category above it includes the divisions below. A two part (binomial) formal designation for each species, following the scheme of Linnaeus, is composed of the capitalized name of the genus (plural = genera) followed by the uncapitalized name of the species (plural = species). Note that the binomial is printed in a special way (italics) to distinguish it. After at least 5000 years of domestication, man has drawn out of that species such a variety of traits through selection and cross-breeding that it may be more difficult to realize that all such cats belong to the same species than it is to recognize that they share the same genus with the lion (Felis leo), leopard (Felis pardus), jaguar (Felis onca), tiger (Felis tigris), and the cougar or puma (Felis concolor). All wildcats belong to the same genus but are classified in three separate species found in Europe, Africa, and the Americas (the ocelot), Felis sylvestris, F.