Shell Microstructures in Early Mollusks
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Review of the Geology and Paleontology of the Ellsworth Mountains, Antarctica
U.S. Geological Survey and The National Academies; USGS OF-2007-1047, Short Research Paper 107; doi:10.3133/of2007-1047.srp107 Review of the geology and paleontology of the Ellsworth Mountains, Antarctica G.F. Webers¹ and J.F. Splettstoesser² ¹Department of Geology, Macalester College, St. Paul, MN 55108, USA ([email protected]) ²P.O. Box 515, Waconia, MN 55387, USA ([email protected]) Abstract The geology of the Ellsworth Mountains has become known in detail only within the past 40-45 years, and the wealth of paleontologic information within the past 25 years. The mountains are an anomaly, structurally speaking, occurring at right angles to the Transantarctic Mountains, implying a crustal plate rotation to reach the present location. Paleontologic affinities with other parts of Gondwanaland are evident, with nearly 150 fossil species ranging in age from Early Cambrian to Permian, with the majority from the Heritage Range. Trilobites and mollusks comprise most of the fauna discovered and identified, including many new genera and species. A Glossopteris flora of Permian age provides a comparison with other Gondwana floras of similar age. The quartzitic rocks that form much of the Sentinel Range have been sculpted by glacial erosion into spectacular alpine topography, resulting in eight of the highest peaks in Antarctica. Citation: Webers, G.F., and J.F. Splettstoesser (2007), Review of the geology and paleontology of the Ellsworth Mountains, Antarctica, in Antarctica: A Keystone in a Changing World – Online Proceedings of the 10th ISAES, edited by A.K. Cooper and C.R. Raymond et al., USGS Open- File Report 2007-1047, Short Research Paper 107, 5 p.; doi:10.3133/of2007-1047.srp107 Introduction The Ellsworth Mountains are located in West Antarctica (Figure 1) with dimensions of approximately 350 km long and 80 km wide. -
Donacidae - Bivalvia)
Bolm. Zool., Univ. S. P aub 3:121-142, 1978 FUNCTIONAL ANATOMY OF DON AX HANLEY ANUS PHILIPPI 1847 (DONACIDAE - BIVALVIA) Walter Narchi Department o f Zoology University o f São Paulo, Brazil ABSTRACT Donax hanleyanus Philippi 1847 occurs throughout the southern half o f the Brazilian littoral. The main organ systems were studied in the living animal, particular attention being paid to the cilia ry feeding and cleasing mechanisms in the mantle cavity. The anatomy, functioning of the stomach and the ciliary sorting mechanisms are described. The stomach unlike that of almost all species of Donax and like the majority of the Tellinacea belongs to type V, as defined by Purchon, and could be regarded as advanced for the Donacidae. A general comparison has been made between the known species of Donax and some features of Iphigenia brasiliensis Lamarck 1818, also a donacid. INTRODUCTION Very little is known of donacid bivalves from the Brazilian littoral. Except for the publications of Narchi (1972; 1974) on Iphigenia brasiliensis and some ecological and adaptative features on Donax hanleyanus, all references to them are brief descrip tions of the shell and cheklists drawn up from systematic surveys. Beach clams of the genus Donax inhabit intertidal sandy shores in most parts of the world. Donax hanleyanus Philippi 1847 is one of four species occuring through out the Brazilian littoral. Its known range includes Espirito Santo State and the sou thern Atlantic shoreline down to Uruguay (Rios, 1975). According to Penchaszadeh & Olivier (1975) the species occur in the littoral of Argentina. 122 Walter Narchi The species is fairly common in São Paulo, Parana and Santa Catarina States whe re it is used as food by the coastal population (Goffeijé, 1950), and is known as “na- nini” It is known by the name “beguara” (Ihering, 1897) in the Iguape region, but not in S. -
Estructura Poblacional De Donax Striatus (Bivalvia, Donacidae) En Playa Las Balsas, Gibara, Cuba
ESTRUCTURA POBLACIONAL DE DONAX STRIATUS (BIVALVIA, DONACIDAE) EN PLAYA LAS BALSAS, GIBARA, CUBA Frank A. Ocaña Borrego1*, Alejandro Fernández1, Alexis Silva2, Pedro A. González1 y Yamilet García2 RESUMEN Donax striatus Linné 1767 es una de las dos especies de almejas de playa que se encuentra en el Caribe. Pocas investigaciones se han centrado en describir aspectos sobre la estructura poblacional de esta especie. Una po- blación de D. striatus fue muestreada mensualmente desde febrero del 2008 hasta enero del 2009 en playa Las Balsas, Gibara, Cuba. La población mostró fluctuaciones estacionales de la densidad, presentando los mayores valores en los meses de mayo y octubre del 2008 y enero del 2009. Se encontraron tres picos de reclutamiento: abril-mayo, agosto del 2008 y enero del 2009. Se observó una distribución estratificada por grupos de tallas: los reclutas fueron registrados en los estratos superiores de la playa y los adultos, fundamentalmente, en los es- tratos bajos. La mayor abundancia se localizó en el estrato intermedio. No hubo correlación entre los cambios mensuales de densidad con las temperaturas, ni con las precipitaciones, sin embargo, parece que los cambios en el régimen habitual del oleaje y la elevación del nivel medio del mar tienen influencia sobre el comporta- miento de la abundancia de esta especie. Se propone una hipótesis que combina parámetros morfodinámicos para explicar la distribución vertical de los diferentes componentes de la población. Palabras claves: Bivalvia, Donax, playas arenosas, estructura poblacional, Cuba. ABSTRACT Donax striatus Linné 1767 is one of the two beach clam species that inhabits in the Caribbean. Few in- vestigations have focused on describing aspects related with the population structure of this species. -
Morphology and Systematic Position of Tryhlidium Canadense Whiteaves
Morphology and systematic position of Tryblidium canadense Whiteaves, 1884 (Mollusca) from the Silurian of North America JOHNS. PEEL Peel, J. S.: Morphology and systematic position of Tryblidium Canadense Whiteaves, 1884 (Mollusca) from the Silurian of North America. Bull. geol. Soc. Denmark, vol. 38, pp. 43-51. Copenhagen, April 25th, 1990. https://doi.org/10.37570/bgsd-1990-38-04 The nomenclative history of Tryblidium canadense Whiteaves, 1884, a large, oval, univalved mollusc originally described from the Silurian Guelph Formation of Ontario, is reviewed. Following comparison to Archinace/la Ulrich & Scofield, 1897, in which genus it has generally been placed for almost a century, Whiteaves' species is redescribed and assigned to a new gastropod genus, Guelphinace/la. John S. Peel, Geological Survey of Greenland, Oster Voldgade JO, 1350 Copenhagen K, Denmark. February 10th, 1989. Whiteaves (1884) described a single internal the sub-apical wall. He commented that the mould of a large (45 mm), oval, univalved mol structure seemed to be a single continuous mus lusc from the Guelph Formation (Silurian) of cular impression and not two separate depres Hespeler, Ontario, Canada as Tryblidium Cana sions, as suggested by Lindstrom (1884), al dense (Fig. 1). Uncertainty surrounding its sys though he did not refer directly to the latter's tematic position developed immediately when description. He made no reference to the thin Lindstrom (1884) questioned the assignment to dorsal band which Lindstrom (1884) had consid the genus Tryblidium -
Shell Microstructures in Early Cambrian Molluscs
Shell microstructures in Early Cambrian molluscs ARTEM KOUCHINSKY Kouchinsky, A. 2000. Shell microstructures in Early Cambrian molluscs. - Acta Palaeontologica Polonica 45,2, 119-150. The affinities of a considerable part of the earliest skeletal fossils are problematical, but investigation of their microstructures may be useful for understanding biomineralization mechanisms in early metazoans and helpful for their taxonomy. The skeletons of Early Cambrian mollusc-like organisms increased by marginal secretion of new growth lamel- lae or sclerites, the recognized basal elements of which were fibers of apparently aragon- ite. The juvenile part of some composite shells consisted of needle-like sclerites; the adult part was built of hollow leaf-like sclerites. A layer of mineralized prism-like units (low aragonitic prisms or flattened spherulites) surrounded by an organic matrix possibly existed in most of the shells with continuous walls. The distribution of initial points of the prism-like units on a periostracurn-like sheet and their growth rate were mostly regular. The units may be replicated on the surface of internal molds as shallow concave poly- gons, which may contain a more or less well-expressed tubercle in their center. Tubercles are often not enclosed in concave polygons and may co-occur with other types of tex- tures. Convex polygons seem to have resulted from decalcification of prism-like units. They do not co-occur with tubercles. The latter are interpreted as casts of pore channels in the wall possibly playing a role in biomineralization or pits serving as attachment sites of groups of mantle cells. Casts of fibers and/or lamellar units may overlap a polygonal tex- ture or occur without it. -
Um Éon De História Dos Bivalvia: Ideias Sobre a Sua Origem, Filogenia E Importância Paleontológica E Educativa
Um Éon de história dos Bivalvia: ideias sobre a sua origem, filogenia e importância paleontológica e educativa Ricardo J. Pimentel1, Pedro M. Callapez2 & Paulo Legoinha3 1 Agrupamento de Escolas de Guia, P-3105 075 Guia, Pombal, Portugal. E-mail: [email protected] 2 Universidade de Coimbra, CITEUC - Centro de Investigação da Terra e do Espaço da Universidade de Coimbra, Faculdade de Ciências e Tecnologia, Departamento de Ciências da Terra, Polo II, Rua Sílvio Lima, P-3030 790 Coimbra, Portugal. E-mail: [email protected] 3 Universidade NOVA de Lisboa, GEOBIOTEC - GeoBiociências, Geotecnologias e Geoengenharias, Faculdade de Ciências e Tecnologia, Departamento de Ciências da Terra, Quinta da Torre, P-2829 516 Caparica, Portugal. E-mail: [email protected] Resumo: A Classe Bivalvia, cuja monofilia se encontra bem suportada por estudos recentes, destaca-se como o segundo taxon, em termos de biodiversidade, do Filo Mollusca. O registo da sua história evolutiva remonta ao Fortuniano (Câmbrico). Diversos dados paleontológicos fundamentados no registo fóssil sugerem que os bivalves atuais são, sobretudo, herdeiros de carateres morfológicos e requisitos ecológicos transmitidos por linhagens da transição devónico-carbonífera. Estes invertebrados habitam a maioria dos ambientes aquáticos atuais e constituem um dos principais grupos de animais invertebrados da biosfera atual, são herdeiros de uma longa história evolutiva e ecológica que é intrínseca à própria história biótica dos oceanos durante o Fanerozoico. São um exemplo de sucesso entre as comunidades bióticas e a sua abundância, diversidade e acessibilidade propiciam a sua utilização como recursos educativos em Ciências Naturais. Palavras-chave: Bivalvia, Educação científica, Filogenia, Mollusca, Registo fóssil. -
Constraints on the Timescale of Animal Evolutionary History
Palaeontologia Electronica palaeo-electronica.org Constraints on the timescale of animal evolutionary history Michael J. Benton, Philip C.J. Donoghue, Robert J. Asher, Matt Friedman, Thomas J. Near, and Jakob Vinther ABSTRACT Dating the tree of life is a core endeavor in evolutionary biology. Rates of evolution are fundamental to nearly every evolutionary model and process. Rates need dates. There is much debate on the most appropriate and reasonable ways in which to date the tree of life, and recent work has highlighted some confusions and complexities that can be avoided. Whether phylogenetic trees are dated after they have been estab- lished, or as part of the process of tree finding, practitioners need to know which cali- brations to use. We emphasize the importance of identifying crown (not stem) fossils, levels of confidence in their attribution to the crown, current chronostratigraphic preci- sion, the primacy of the host geological formation and asymmetric confidence intervals. Here we present calibrations for 88 key nodes across the phylogeny of animals, rang- ing from the root of Metazoa to the last common ancestor of Homo sapiens. Close attention to detail is constantly required: for example, the classic bird-mammal date (base of crown Amniota) has often been given as 310-315 Ma; the 2014 international time scale indicates a minimum age of 318 Ma. Michael J. Benton. School of Earth Sciences, University of Bristol, Bristol, BS8 1RJ, U.K. [email protected] Philip C.J. Donoghue. School of Earth Sciences, University of Bristol, Bristol, BS8 1RJ, U.K. [email protected] Robert J. -
Durham Research Online
Durham Research Online Deposited in DRO: 23 May 2017 Version of attached le: Accepted Version Peer-review status of attached le: Peer-reviewed Citation for published item: Betts, Marissa J. and Paterson, John R. and Jago, James B. and Jacquet, Sarah M. and Skovsted, Christian B. and Topper, Timothy P. and Brock, Glenn A. (2017) 'Global correlation of the early Cambrian of South Australia : shelly fauna of the Dailyatia odyssei Zone.', Gondwana research., 46 . pp. 240-279. Further information on publisher's website: https://doi.org/10.1016/j.gr.2017.02.007 Publisher's copyright statement: c 2017 This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ Additional information: Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full DRO policy for further details. Durham University Library, Stockton Road, Durham DH1 3LY, United Kingdom Tel : +44 (0)191 334 3042 | Fax : +44 (0)191 334 2971 https://dro.dur.ac.uk Accepted Manuscript Global correlation of the early Cambrian of South Australia: Shelly fauna of the Dailyatia odyssei Zone Marissa J. -
Facies, Phosphate, and Fossil Preservation Potential Across a Lower Cambrian Carbonate Shelf, Arrowie Basin, South Australia
Palaeogeography, Palaeoclimatology, Palaeoecology 533 (2019) 109200 Contents lists available at ScienceDirect Palaeogeography, Palaeoclimatology, Palaeoecology journal homepage: www.elsevier.com/locate/palaeo Facies, phosphate, and fossil preservation potential across a Lower Cambrian T carbonate shelf, Arrowie Basin, South Australia ⁎ Sarah M. Jacqueta,b, , Marissa J. Bettsc,d, John Warren Huntleya, Glenn A. Brockb,d a Department of Geological Sciences, University of Missouri, Columbia, MO 65211, USA b Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia c Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia d Early Life Institute and Department of Geology, State Key Laboratory for Continental Dynamics, Northwest University, Xi'an 710069, China ARTICLE INFO ABSTRACT Keywords: The efects of sedimentological, depositional and taphonomic processes on preservation potential of Cambrian Microfacies small shelly fossils (SSF) have important implications for their utility in biostratigraphy and high-resolution Calcareous correlation. To investigate the efects of these processes on fossil occurrence, detailed microfacies analysis, Organophosphatic biostratigraphic data, and multivariate analyses are integrated from an exemplar stratigraphic section Taphonomy intersecting a suite of lower Cambrian carbonate palaeoenvironments in the northern Flinders Ranges, South Biominerals Australia. The succession deepens upsection, across a low-gradient shallow-marine shelf. Six depositional Facies Hardgrounds Sequences are identifed ranging from protected (FS1) and open (FS2) shelf/lagoonal systems, high-energy inner ramp shoal complex (FS3), mid-shelf (FS4), mid- to outer-shelf (FS5) and outer-shelf (FS6) environments. Non-metric multi-dimensional scaling ordination and two-way cluster analysis reveal an underlying bathymetric gradient as the main control on the distribution of SSFs. -
The Youngest Representatives of the Genus Ribeiria Sharpe, 1853 from the Late Katian of the Prague Basin (Bohemia)
Estonian Journal of Earth Sciences, 2015, 64, 1, 84–90 doi: 10.3176/earth.2015.15 The youngest representatives of the genus Ribeiria Sharpe, 1853 from the late Katian of the Prague Basin (Bohemia) Marika Polechová Czech Geological Survey, Klárov 3, 11821 Prague 1, Czech Republic; [email protected] Received 2 July 2014, accepted 6 October 2014 Abstract. Ribeiria apusoides and Ribeiria johni sp. nov. are described from the late Katian of the Prague Basin (Bohemia) as the youngest representatives of the genus Ribeiria. The Ordovician ribeirioids from Bohemia (Perunica) show close affinities to the ribeirioids from Armorica and Iberia. The functional morphology of ribeirioids, mainly the pedal muscle system, is discussed, based on very well-preserved specimens of R. apusoides. The ribeirioids attained their diversity in the Lower Ordovician, since the Middle Ordovician their diversity declines, and during the late Katian only three genera are known worldwide. They are unknown from the Hirnantian but the last ribeirioids are recorded from the lower Silurian in South China. Key words: Ribeirioida, systematics, functional morphology, Ordovician, Prague Basin. INTRODUCTION Pojeta & Runnegar (1976) briefly described and figured all known species of rostroconchs, including also species The study of rostroconchs was started by Martin (1809) of ribeirioids from the Ordovician of the Prague Basin and Sowerby (1815), but the systematic position of the (Czech Republic). The rich material of rostroconchs group was for a long time unclear. Rostroconchs were from the Czech Republic is one of the best-preserved allied mainly to bivalves (Branson et al. 1969) or materials. It includes ribeirioids from the late Katian even to arthropods (Schubert & Waagen 1904; Kobayashi (Králův Dvůr Formation), among them the worldwide 1933). -
A Molecular Phylogeny of the Patellogastropoda (Mollusca: Gastropoda)
^03 Marine Biology (2000) 137: 183-194 ® Spnnger-Verlag 2000 M. G. Harasevvych A. G. McArthur A molecular phylogeny of the Patellogastropoda (Mollusca: Gastropoda) Received: 5 February 1999 /Accepted: 16 May 2000 Abstract Phylogenetic analyses of partiaJ J8S rDNA formia" than between the Patellogastropoda and sequences from species representing all living families of Orthogastropoda. Partial 18S sequences support the the order Patellogastropoda, most other major gastro- inclusion of the family Neolepetopsidae within the su- pod groups (Cocculiniformia, Neritopsma, Vetigastro- perfamily Acmaeoidea, and refute its previously hy- poda, Caenogastropoda, Heterobranchia, but not pothesized position as sister group to the remaining Neomphalina), and two additional classes of the phylum living Patellogastropoda. This region of the Í8S rDNA Mollusca (Cephalopoda, Polyplacophora) confirm that gene diverges at widely differing rates, spanning an order Patellogastropoda comprises a robust clade with high of magnitude among patellogastropod lineages, and statistical support. The sequences are characterized by therefore does not provide meaningful resolution of the the presence of several insertions and deletions that are relationships among higher taxa of patellogastropods. unique to, and ubiquitous among, patellogastropods. Data from one or more genes that evolve more uni- However, this portion of the 18S gene is insufficiently formly and more rapidly than the ISSrDNA gene informative to provide robust support for the mono- (possibly one or more -
Keeping a Lid on It: Muscle Scars and the Mystery of the Mobergellidae
1 Keeping a lid on it: muscle scars and the mystery of the 2 Mobergellidae 3 4 TIMOTHY P. TOPPER1,2* and CHRISTIAN B. SKOVSTED1 5 6 1Department of Palaeobiology, Swedish Museum of Natural History, P.O. Box 50007, 7 SE-104 05, Stockholm, Sweden. 8 2Palaeoecosystems Group, Department of Earth Sciences, Durham University, Durham 9 DH1 3LE, UK. 10 11 Mobergellans were one of the first Cambrian skeletal groups to be recognized yet have 12 long remained one of the most problematic in terms of biological function and affinity. 13 Typified by a disc-shaped, phosphatic sclerite the most distinctive character of the 14 group is a prominent set of internal scars, interpreted as representing sites of former 15 muscle attachment. Predominantly based on muscle scar distribution, mobergellans 16 have been compared to brachiopods, bivalves and monoplacophorans, however a 17 recurring theory that the sclerites acted as operculum remains untested. Rather than 18 correlate the number of muscle scars between taxa, here we focus on the percentage of 19 the inner surface shell area that the scars constitute. We investigate two mobergellan 20 species, Mobergella holsti and Discinella micans comparing the Cambrian taxa with the 21 muscle scars of a variety of extant and fossil marine invertebrate taxa to test if the 22 mobergellan muscle attachment area is compatible with an interpretation as operculum. 23 The only skeletal elements in our study with a comparable muscle attachment 24 percentage are gastropod opercula. Complemented with additional morphological 25 information, our analysis supports the theory that mobergellan sclerites acted as an 26 operculum presumably from a tube-living organism.