DOCSLIB.ORG

Early Cambrian Animal Diapause Embryos Revealed by X-Ray Tomography

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Early Cambrian Animal Diapause Embryos Revealed by X-Ray Tomography Early Cambrian animal diapause embryos revealed by X-ray tomography Zongjun Yin1,2*, Duoduo Zhao1, Bing Pan1, Fangchen Zhao1,2, Han Zeng1, Guoxiang Li1,2, David J. Bottjer3, and Maoyan Zhu1,2,4 1State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China 2Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing 210008, China 3Department of Earth Sciences, University of Southern California, Los Angeles, California 90089, USA 4College of Earth Sciences, University of Chinese Academy of Sciences, Shijingshan, Beijing 100049, China ABSTRACT hypotheses on the affinity of this enigmatic early Discoveries of animal embryos have profoundly improved our understanding of the early Cambrian organism. evolution of animal development. However, the fossil record of early animal embryos is extremely sparse. Here we present some three-dimensionally (3-D) phosphatized Archaeooi- MATERIALS AND METHODS des from the basal Cambrian in southern Shaanxi Province, China. The 3-D reconstructions The fossils were collected from the lower of a number of specimens, aided by high-resolution X-ray tomography, demonstrate that Cambrian Kuanchuanpu Formation of the Hexi these soft-bodied fossil organisms have a thick cyst characterized by pustule-like ornaments section in Xixiang County, Shaanxi Province, and vesicular structures. Furthermore, a multicellular inner body undergoing palintomic China (Fig. DR1 in the GSA Data Repository1). cell division is enclosed by the cyst. The suite of characters, including submillimeter to mil- Contemporaneous small shelly fossils indicate limeter scale, a palintomic pattern of cell division, and a complex cyst wall microstructure, that Archaeooides occurred in the earliest Cam- corroborate the hypothesis that Archaeooides fossils represent the embryonic remains of brian Anabarites trisulcatus–Protohertzina ana­ animals. More specifically, the structure of the cyst wall bears close comparison to the resting barica Zone dated to 537–532 Ma (Steiner et cysts of living invertebrates, allowing us to interpret Archaeooides as a diapause embryonic al., 2014). stage adapted to the temporally and spatially heterogeneous redox conditions that extended The fossils were recovered from limestone from the Ediacaran to the early Cambrian. The global distribution of Archaeooides indicates using acetic acid digestion (acid concentration of that these conditions were geographically widespread. Ultimately, Archaeooides provides evi- 3%) and manual sorting of the ensuing insoluble dence of the early evolution of this metazoan life history strategy as an adaptation to adverse residue under a binocular microscope. Selected environmental conditions. Its widespread occurrence in both conventional and exceptional specimens were scanned at the Micro-CT Lab at taphonomic windows provides the potential for reconstructing its embryology and, by infer- the Nanjing Institute of Geology and Palaeontol- ence, the developmental evolution of early animals and their body plans. ogy, Chinese Academy of Sciences (NIGPAS), using a Zeiss Xradia 520 Versa. To achieve INTRODUCTION Four Cambrian taxa of phosphatized spheri- good contrast, we used a 50 kV operating volt- The fossil record of early animals has docu- cal fossils, Archaeooides, Olivooides, Pseudooi­ age of the X-ray tube, with a thin filter (LE1) mented an early Cambrian explosion of meta- des, and Markuelia, have all been interpreted as to avoid beam-hardening artifacts. Depending zoan body plans, evidenced by the stratigraphic preserving embryonic stages of development on the sizes of the specimens, two charge-cou- first occurrences of fossils of almost all animal (Qian, 1977; Bengtson and Yue, 1997). Among pled device (CCD)–based optical microscopes phyla in the early Cambrian (Erwin et al., 2011). them, Olivooides, Pseudooides, and Markuelia (4× and 20×) were applied. This system pro- However, little is known about the embryologi- have been the focus of most attention (Dono- duces data sets with voxel dimensions ranging cal evolution of these body plans due to a paucity ghue et al., 2015), while the more widely distrib- between 0.56 µm and 1.63 µm. For each scan, of fossil embryonic remains of animals. Dur- uted Archaeooides has been overlooked. Conse- we obtained 3000 equi-angular projections over ing the past two decades, discoveries of fossil quently, its biological affinity remains uncertain 360°. The exposure time for each projection was embryos have provided insight into the embry- because little is known of its internal structure, 5–10 s, depending on the density and diameter ology of early animals and, therefore, the evo- even though some authors have speculated that of specimens. The volume data were processed lution of animal development (Bengtson and it may be an animal egg or embryo (Qian and using VGSTUDIO MAX software (https://www Yue, 1997; Xiao et al., 1998; Dong et al., 2004; Bengtson, 1989; Pyle et al., 2006). .volumegraphics.com /en /products /vgstudio -max Steiner et al., 2004; Chen et al., 2006; Yin et al., In an attempt to test previous hypotheses on .html). All of the specimens are housed at NIG- 2007; Yin et al., 2016). However, fossil embryos the nature and biological affinity of Archaeooi­ PAS, and the tomographic data are available are extremely rare, in terms of their diversity, des, we used high-resolution X-ray tomogra- from the Geobiodiversity Database (http://www abundance, and stratigraphic distribution (Dono- phy to characterize the three-dimensional (3-D) .geobiodiversity.com/). ghue et al., 2006). Therefore, the discovery of structure of a number of specimens. Our results new fossils of animal embryos from the Neo- indicate that these specimens preserve not only proterozoic-Paleozoic transitional interval is of a complex envelope, but also an inner body with 1 GSA Data Repository item 2018126, Figure DR1 (locality and stratigraphy of the Hexi Section great significance. multicellular structure. This is the first report in Shaanxi, China), is available online at http://www on the 3-D structure of Archaeooides, and our .geosociety.org/datarepository/2018/ or on request *E-mail: [email protected] data provide strong evidence to test established from [email protected]. GEOLOGY, May 2018; v. 46; no. 5; p. 387–390 | GSA Data Repository item 2018126 | https://doi.org/10.1130/G40081.1 | Published online 23 February 2018 ©GEOLOGY 2018 The Authors.| Volume Gold 46 |Open Number Access: 5 | www.gsapubs.orgThis paper is published under the terms of the CC-BY license. 387 Downloaded from http://pubs.geoscienceworld.org/gsa/geology/article-pdf/46/5/387/4134080/387.pdf by guest on 25 September 2021 Figure 2. Archaeooides from lower Cambrian Kuanchuanpu Formation (China). A–C: Specimen NIGPAS-CK-A01 (NIGPAS—Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences). D–F: Specimen NIGPAS-CK-E01. G–I: Specimen NIGPAS-CK-E11. J–L: Specimen NIGPAS-CK-E04. A, D, G, and J are surface renderings showing ornamented envelope. B, C, F, I, and L are three-dimensional (3-D) renderings with transparent envelope, showing inner Figure 1. Archaeooides from lower Cambrian bodies. E is 3-D rendering showing four-celled inner body enclosed by thick envelope. H is Kuanchuanpu Formation (China), and diam- 3-D section showing four-celled inner body. K is 3-D rendering showing degraded inner body. eter histograms. A,B: Surface renderings showing ornamented envelopes. A: Specimen NIGPAS-CK-F02 (NIGPAS—Nanjing Institute of scale. Some envelopes betray evidence of reconstructions illustrate that the inner body has Geology and Paleontology, Chinese Academy post-mortem decay and diagenetic alteration, no cell structures, and is hollow with many small, of Sciences). B: Specimen NIGPAS-CK-F03. leaving large secondary cavities with diagenetic later void-filling crystals inside (Figs. 2K, 2L, C: Diameter histogram of 206 Archaeooides mineral linings (Figs. 3D and 3D1). Some speci- and 3C), suggesting that the inner body is likely specimens in this study. D: Diameter ranges of Archaeooides, Ediacaran embryos, spiny acri- mens are, however, well preserved, without void- a mineralized mass of degraded cells or tissues. tarchs, and extant bilaterian resting eggs (data filling mineralization, but permeated by micro- are from: this study; Pyle et al., 2006; Cohen fractures (Figs. 3C and 3C1). Almost all of the DISCUSSION et al., 2009; Hill and Shepard, 1997; Bottrell well-preserved specimens exhibit large numbers and Newsome, 1976; Gilbert and Wurdak et al., 1978). Gray horizontal bar highlights the of small vesicular structures (SVSs) that vary Biological Affinity of Archaeooides range of 0–100 μm. within and between specimens (Figs. 3A–3C, The biological affinity of Archaeooides has 3A1–3C1). In some specimens, the SVSs have been poorly constrained largely because knowl- been infilled by crystallites or materials with edge of its biology was limited to cyst morphol- RESULTS lower X-ray attenuation (Figs. 3B, 3B1–3B3). ogy. It has been considered to represent animal Archaeooides is distinguished by subspheri- The envelopes of many specimens are deflated eggs or embryos, but with little evidence to cal to spherical morphologies and an orna- and deformed (Figs. 1A, 1B, and 2A). The plas- support these speculations (Qian and Bengtson, mented envelope (Figs. 1–3). Within our data tic deformation suggest that the envelopes were 1989; Pyle et al., 2006). Our high-resolution
Load more

Recommended publications
  • Reinterpretation of the Enigmatic Ordovician Genus Bolboporites (Echinodermata)
    Reinterpretation of the enigmatic Ordovician genus Bolboporites (Echinodermata). Emeric Gillet, Bertrand Lefebvre, Véronique Gardien, Emilie Steimetz, Christophe Durlet, Frédéric Marin To cite this version: Emeric Gillet, Bertrand Lefebvre, Véronique Gardien, Emilie Steimetz, Christophe Durlet, et al.. Reinterpretation of the enigmatic Ordovician genus Bolboporites (Echinodermata).. Zoosymposia, Magnolia Press, 2019, 15 (1), pp.44-70. 10.11646/zoosymposia.15.1.7. hal-02333918 HAL Id: hal-02333918 https://hal.archives-ouvertes.fr/hal-02333918 Submitted on 13 Nov 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. 1 Reinterpretation of the Enigmatic Ordovician Genus Bolboporites 2 (Echinodermata) 3 4 EMERIC GILLET1, BERTRAND LEFEBVRE1,3, VERONIQUE GARDIEN1, EMILIE 5 STEIMETZ2, CHRISTOPHE DURLET2 & FREDERIC MARIN2 6 7 1 Université de Lyon, UCBL, ENSL, CNRS, UMR 5276 LGL-TPE, 2 rue Raphaël Dubois, F- 8 69622 Villeurbanne, France 9 2 Université de Bourgogne - Franche Comté, CNRS, UMR 6282 Biogéosciences, 6 boulevard 10 Gabriel, F-2100 Dijon, France 11 3 Corresponding author, E-mail: [email protected] 12 13 Abstract 14 Bolboporites is an enigmatic Ordovician cone-shaped fossil, the precise nature and systematic affinities of 15 which have been controversial over almost two centuries.
    [Show full text]
  • Terreneuvian Orthothecid (Hyolitha) Digestive Tracts from Northern Montagne Noire, France; Taphonomic, Ontogenetic and Phylogenetic Implications
    Terreneuvian Orthothecid (Hyolitha) Digestive Tracts from Northern Montagne Noire, France; Taphonomic, Ontogenetic and Phylogenetic Implications Le´a Devaere1*,Se´bastien Clausen1, J. Javier A´ lvaro2, John S. Peel3, Daniel Vachard1 1 UMR 8217 Ge´osyste`mes CNRS – Universite´ Lille 1Villeneuve d’Ascq, France, 2 Centro de Astrobiologı´a, Instituto Nacional de Te´cnica Aeroespacial, Consejo Superior de Investigaciones Cientı´ficas, Torrejo´n de Ardoz, Spain, 3 Department of Earth Sciences (Palaeobiology), Uppsala University, Uppsala, Sweden Abstract More than 285 specimens of Conotheca subcurvata with three-dimensionally preserved digestive tracts were recovered from the Terreneuvian (early Cambrian) Heraultia Limestone of the northern Montagne Noire, southern France. They represent one of the oldest occurrences of such preserved guts. The newly discovered operculum of some complete specimens provides additional data allowing emendation of the species diagnosis. Infestation of the U-shaped digestive tracts by smooth uniseriate, branching to anastomosing filaments along with isolated botryoidal coccoids attests to their early, microbially mediated phosphatisation. Apart from taphonomic deformation, C. subcurvata exhibits three different configurations of the digestive tract: (1) anal tube and gut parallel, straight to slightly undulating; (2) anal tube straight and loosely folded gut; and (3) anal tube straight and gut straight with local zigzag folds. The arrangement of the digestive tracts and its correlation with the mean apertural diameter of the specimens are interpreted as ontogenetically dependent. The simple U-shaped gut, usually considered as characteristic of the Hyolithida, developed in earlier stages of C. subcurvata, whereas the more complex orthothecid type-3 only appears in largest specimens. This growth pattern suggests a distinct phylogenetic relationship between these two hyolith orders through heterochronic processes.
    [Show full text]
  • 1 Rrh: Middle Cambrian Coprolites Lrh: J. Kimmig And
    RRH: MIDDLE CAMBRIAN COPROLITES LRH: J. KIMMIG AND B.R. PRATT Research Article DOI: http://dx.doi.org/10.2110/palo.2017.038 COPROLITES IN THE RAVENS THROAT RIVER LAGERSTÄTTE OF NORTHWESTERN CANADA: IMPLICATIONS FOR THE MIDDLE CAMBRIAN FOOD WEB 1 2 JULIEN KIMMIG AND BRIAN R. PRATT 1Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA 2Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada e-mail: [email protected] ABSTRACT: The Rockslide Formation (middle Cambrian, Drumian, Bolaspidella Zone) of the Mackenzie Mountains, northwestern Canada, hosts the Ravens Throat River Lagerstätte, which consists of two, 1-m thick intervals of greenish, thinly laminated, locally burrowed, slightly calcareous mudstone yielding a low-diversity and low-abundance fauna of bivalved arthropods, ‘worms’, hyoliths, and trilobites. Also present are flattened, circular, black carbonaceous objects averaging 15 mm in diameter, interpreted as coprolites preserved in either dorsal or ventral view. Many consist of aggregates of ovate carbonaceous flakes 0.5–2 mm long, which are probably compacted fecal pellets. Two-thirds contain a variably disarticulated pair of arthropod valves, and many also contain coiled to fragmented, corrugated ‘worm’ cuticle, either alone or together with valves. A few contain an enrolled agnostoid. In rare cases a ptychoparioid cranidium, agnostoid shield, bradoriid valve, or hyolith conch or operculum is present; these are taken to be due to capture and ingestion of bioclasts from the adjacent seafloor. Many of the coprolites are associated with semi-circular spreiten produced by movement of the worm-like predator while it occupied a vertical burrow. Its identity is unknown but it clearly exhibited prey selectivity.
    [Show full text]
  • Oldest Mickwitziid Brachiopod from the Terreneuvian of Southern France
    Oldest mickwitziid brachiopod from the Terreneuvian of southern France LÉA DEVAERE, LARS HOLMER, SÉBASTIEN CLAUSEN, and DANIEL VACHARD Devaere, L., Holmer, L., Clausen, S., and Vachard, D. 2015. Oldest mickwitziid brachiopod from the Terreneuvian of southern France. Acta Palaeontologica Polonica 60 (3): 755–768. Kerberellus marcouensis Devaere, Holmer, and Clausen gen. et sp. nov., originally described as Dictyonina? sp., from the Terreneuvian of northern Montagne Noire (France) is re-interpreted as the oldest relative to or member of mickwitziid- like stem-group brachiopods. We extracted 170 partial to complete phosphatic internal moulds of two types of adult and one type of juvenile disarticulated valves, rarely externally coated with phosphates, from the calcareous Heraultia Member of the Marcou Formation. They correspond to microbially infested, ventribiconvex, inequivalved, bivalved shells. The ventral interarea is bisected by a triangular sinus. The shell, most probably dominantly organic in origin, is orthogonally pierced throughout its entire thickness by radially-aligned, smooth-walled, cylindrical to hour-glass shaped canals except for the sub-apical planar field (interarea). The through-going canals of K. marcouensis are compared with brachiopods endopunctae and with canals of mickwitziid brachiopods. The absence of striations on K. marcouensis canal walls, typical of mickwitziids, implies that (i) the tubes could have been depleted of setae or; (ii) traces of the microvilli were not preserved on the tube wall (taphonomic bias) or, (iii) the tubes could have been associated with an outer epithelial follicle. Key words: Brachiopoda, Mickwitziidae, shell canals, Cambrian, Terreneuvian, West Gondwana, France. Léa Devaere [[email protected]], Sébastien Clausen [[email protected]], and Daniel Vachard [[email protected]], UMR 8217 Géosystèmes CNRS-Université Lille 1, bâtiment SN5, avenue Paul Lan- gevin, 59655 Villeneuve d’Ascq, France.
    [Show full text]
  • Chapter 5. Paleozoic Invertebrate Paleontology of Grand Canyon National Park
    Chapter 5. Paleozoic Invertebrate Paleontology of Grand Canyon National Park By Linda Sue Lassiter1, Justin S. Tweet2, Frederick A. Sundberg3, John R. Foster4, and P. J. Bergman5 1Northern Arizona University Department of Biological Sciences Flagstaff, Arizona 2National Park Service 9149 79th Street S. Cottage Grove, Minnesota 55016 3Museum of Northern Arizona Research Associate Flagstaff, Arizona 4Utah Field House of Natural History State Park Museum Vernal, Utah 5Northern Arizona University Flagstaff, Arizona Introduction As impressive as the Grand Canyon is to any observer from the rim, the river, or even from space, these cliffs and slopes are much more than an array of colors above the serpentine majesty of the Colorado River. The erosive forces of the Colorado River and feeder streams took millions of years to carve more than 290 million years of Paleozoic Era rocks. These exposures of Paleozoic Era sediments constitute 85% of the almost 5,000 km2 (1,903 mi2) of the Grand Canyon National Park (GRCA) and reveal important chronologic information on marine paleoecologies of the past. This expanse of both spatial and temporal coverage is unrivaled anywhere else on our planet. While many visitors stand on the rim and peer down into the abyss of the carved canyon depths, few realize that they are also staring at the history of life from almost 520 million years ago (Ma) where the Paleozoic rocks cover the great unconformity (Karlstrom et al. 2018) to 270 Ma at the top (Sorauf and Billingsley 1991). The Paleozoic rocks visible from the South Rim Visitors Center, are mostly from marine and some fluvial sediment deposits (Figure 5-1).
    [Show full text]
  • Brachiopod-Dominated Communities and Depositional Environment of the Guanshan Konservat-Lagerstätte, Eastern Yunnan, China
    Downloaded from http://jgs.lyellcollection.org/ by guest on October 1, 2021 Research article Journal of the Geological Society Published Online First https://doi.org/10.1144/jgs2020-043 Brachiopod-dominated communities and depositional environment of the Guanshan Konservat-Lagerstätte, eastern Yunnan, China Feiyang Chen1,2, Glenn A. Brock1,2, Zhiliang Zhang1,2, Brittany Laing2,3, Xinyi Ren1 and Zhifei Zhang1* 1 State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life & Environments and Department of Geology, Northwest University, Xi’an, 710069, China 2 Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia 3 Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada FC, 0000-0001-8994-4187; GAB, 0000-0002-2277-7350; Z-LZ, 0000-0003-2296-5973; BL, 0000-0002-0874-8879; Z-FZ, 0000-0003-0325-5116 * Correspondence: [email protected]; [email protected] Abstract: The Guanshan Biota is an unusual early Cambrian Konservat-Lagerstätte from China and is distinguished from all other exceptionally preserved Cambrian biotas by the dominance of brachiopods and a relatively shallow depositional environment. However, the faunal composition, overturn and sedimentology associated with the Guanshan Biota are poorly understood. This study, based on collections through the best-exposed succession of the basal Wulongqing Formation at the Shijiangjun section, Wuding County, eastern Yunnan, China recovered six major animal groups with soft tissue preservation; brachiopods vastly outnumbered all other groups. Brachiopods quickly replace arthropods as the dominant fauna following a transgression at the base of the Wulongqing Formation. A transition from a botsfordiid-, eoobolid- and acrotretid- to an acrotheloid-dominated brachiopod assemblage occurs up-section.
    [Show full text]
  • Paleoecology of the Greater Phyllopod Bed Community, Burgess Shale ⁎ Jean-Bernard Caron , Donald A
    Available online at www.sciencedirect.com Palaeogeography, Palaeoclimatology, Palaeoecology 258 (2008) 222–256 www.elsevier.com/locate/palaeo Paleoecology of the Greater Phyllopod Bed community, Burgess Shale ⁎ Jean-Bernard Caron , Donald A. Jackson Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada M5S 3G5 Accepted 3 May 2007 Abstract To better understand temporal variations in species diversity and composition, ecological attributes, and environmental influences for the Middle Cambrian Burgess Shale community, we studied 50,900 fossil specimens belonging to 158 genera (mostly monospecific and non-biomineralized) representing 17 major taxonomic groups and 17 ecological categories. Fossils were collected in situ from within 26 massive siliciclastic mudstone beds of the Greater Phyllopod Bed (Walcott Quarry — Fossil Ridge). Previous taphonomic studies have demonstrated that each bed represents a single obrution event capturing a predominantly benthic community represented by census- and time-averaged assemblages, preserved within habitat. The Greater Phyllopod Bed (GPB) corresponds to an estimated depositional interval of 10 to 100 KA and thus potentially preserves community patterns in ecological and short-term evolutionary time. The community is dominated by epibenthic vagile deposit feeders and sessile suspension feeders, represented primarily by arthropods and sponges. Most species are characterized by low abundance and short stratigraphic range and usually do not recur through the section. It is likely that these are stenotopic forms (i.e., tolerant of a narrow range of habitats, or having a narrow geographical distribution). The few recurrent species tend to be numerically abundant and may represent eurytopic organisms (i.e., tolerant of a wide range of habitats, or having a wide geographical distribution).
    [Show full text]
  • SKELETAL MICROSTRUCTURE INDICATES CHANCELLORIIDS and HALKIERIIDS ARE CLOSELY RELATED by SUSANNAH M
    [Palaeontology, Vol. 51, Part 4, 2008, pp. 865–879] SKELETAL MICROSTRUCTURE INDICATES CHANCELLORIIDS AND HALKIERIIDS ARE CLOSELY RELATED by SUSANNAH M. PORTER Department of Earth Science, University of California at Santa Barbara, Santa Barbara, CA 93106, USA; e-mail: [email protected] Typescript received 7 November 2005; accepted in revised form 7 September 2007 Abstract: Chancelloriids are problematic, sac-like animals and siphogonuchitid sclerites are homologous. The difference whose sclerites are common in Cambrian fossil assemblages. in chancelloriid and halkieriid body plans can be resolved in They look like sponges, but were united with the slug-like two ways. Chancelloriids either represent a derived condition halkieriids in the group Coeloscleritophora Bengtson and exhibiting complete loss of bilaterian characters or they repre- Missarzhevsky, 1981 based on a unique mode of sclerite con- sent the ancestral condition from which the bilaterally sym- struction. Because their body plans are so different, this pro- metric halkieriids, and the Bilateria as a whole, derived. The posal has never been well accepted, but detailed study of their latter interpretation, proposed by Bengtson (2005), implies sclerite microstructure presented here provides additional that coeloscleritophoran sclerites (‘coelosclerites’) are a plesi- support for this grouping. Both taxa possess walls composed omorphy of the Bilateria, lost or transformed in descendent of a thin, probably organic, sheet overlying a single layer of lineages. Given that mineralized coelosclerites appear in the aragonite fibres orientated parallel to the long axis of the fossil record no earlier than c. 542 Ma, this in turn implies sclerite. In all halkieriids and in the chancelloriid genus Archi- either that the Ediacaran record of bilaterians has been misin- asterella Sdzuy, 1969, bundles of these fibres form inclined terpreted or that coelosclerite preservability increased at the projections on the upper surface of the sclerite giving it a beginning of the Cambrian Period.
    [Show full text]
  • New Insight Into the Soft Anatomy and Shell Microstructures of Early Cambrian 2 Orthothecids (Hyolitha) 3 4 Luoyang Li1,2, Christian B
    1 New insight into the soft anatomy and shell microstructures of early Cambrian 2 orthothecids (Hyolitha) 3 4 Luoyang Li1,2, Christian B. Skovsted1,2, Hao Yun2, Marissa J. Betts2,3, Xingliang 5 Zhang2, 6 7 1Department of Palaeobiology, Swedish Museum of Natural History, Box 50007, SE- 8 104 05 Stockholm, Sweden. 9 2State Key Laboratory of Continental Dynamics, Shaanxi Key laboratory of Early 10 Life and Environments, Department of Geology, Northwest University, Xi’an 710069, 11 PR China. 12 3Palaeoscience Research Centre, School of Environmental and Rural Science, 13 University of New England, Armidale, NSW, Australia, 2351 14 E-mail for correspondence: [email protected] 15 16 Abstract 17 Hyoliths (hyolithids and orthothecids) were one of the most successful early 18 biomineralizing lophotrochozoans, and were a key component of the Cambrian 19 evolutionary fauna. However, the morphology, skeletogenesis and anatomy of earliest 20 members of this enigmatic clade, as well as its relationship with other 21 lophotrochozoan phyla remain highly contentious. Here we present a new orthothecid, 22 Longxiantheca mira gen. et sp. nov. preserved as part of the secondarily phosphatized 23 Small Shelly Fossil assemblage from the lower Cambrian Xinji Formation of North 24 China. Longxiantheca mira retains some ancestral traits of the clade with an 25 undifferentiated disc-shaped operculum and a simple conical conch with a two- 26 layered microstructure of aragonitic fibrous bundles. The operculum interior exhibits 27 impressions of soft tissues, including muscle attachment scars, mantle epithelial cells 28 and a central kidney-shaped platform in association with its feeding organ. Our study 29 reveals that the muscular system and tentaculate feeding apparatus in orthothecids 30 appear to be similar to that in hyolithids, suggesting a consistent anatomical 31 configuration among the total group of hyoliths.
    [Show full text]
  • Distribution and Ecology of Soft-Bottom Sipuncula from the Western Mediterranean Sea
    Distribution and ecology of soft-bottom Sipuncula from the western Mediterranean Sea Luis Miguel Ferrero Vicente DOCTORADO EN CIENCIAS DEL MAR Y BIOLOGÍA APLICADA Distribution and ecology of soft-bottom Sipuncula from the western Mediterranean Sea Distribución y ecología de los sipuncúlidos de fondos blandos del mar Mediterráneo occidental Memoria presentada para optar al grado de Doctor Internacional en la Universidad de Alicante por LUIS MIGUEL FERRERO-VICENTE ALICANTE, Octubre 2014 Dirigida por: Dr. José Luis Sánchez Lizaso «If I saw further than other men, it was because I stood on the shoulders of giants» —Isaac Newton Agradecimientos /Acknowledgements AGRADECIMIENTOS / ACKNOWLEDGEMENTS En primer lugar quiero agradecer a la Mancomunidad de los Canales del Taibilla la financiación aportada a través de los diferentes proyectos en los que hemos colaborado. También agradezco a José Luis el haberme ofrecido la oportunidad de trabajar en lo que me gusta, el mar y los animales, aunque sean pequeños y raros. Muchas gracias por la confianza, por permitirme realizar esta tesis y participar en otros proyectos de investigación en los que tantas cosas he aprendido. En un plano más personal quiero expresar mi gratitud a toda mi familia y amigos, especialmente a mis padres y hermanos, que saben lo difícil que ha sido este camino. Parecía que nunca iba a llegar el momento de terminar, pero al fin ha llegado, muchas gracias por todo vuestro apoyo. También mi agradecimiento a Ángel Loya, porque sin él está oportunidad posiblemente no habría existido, y por todo su apoyo y amistad durante estos años. Él lo ha vivido conmigo, los momentos buenos y también los malos.
    [Show full text]
  • Pelagiella Exigua, an Early Cambrian Stem Gastropod With
    [Palaeontology, Vol. 63, Part 4, 2020, pp. 601–627] PELAGIELLA EXIGUA,ANEARLYCAMBRIAN STEM GASTROPOD WITH CHAETAE: LOPHOTROCHOZOAN HERITAGE AND CONCHIFERAN NOVELTY by ROGER D. K. THOMAS1 , BRUCE RUNNEGAR2 and KERRY MATT3 1Department of Earth & Environment, Franklin & Marshall College, PO Box 3003, Lancaster, PA 17604-3003, USA; [email protected] 2Department of Earth, Planetary, & Space Sciences & Molecular Biology Institute, University of California, Los Angeles, CA 90095-1567, USA 3391 Redwood Drive, Lancaster, PA 17603-4232, USA Typescript received 8 October 2018; accepted in revised form 4 December 2019 Abstract: Exceptionally well-preserved impressions of two appendages were anterior–lateral, based on their probable bundles of bristles protrude from the apertures of small, functions, prompts a new reconstruction of the anatomy of spiral shells of Pelagiella exigua, recovered from the Kinzers Pelagiella, with a mainly anterior mantle cavity. Under this Formation (Cambrian, Stage 4, ‘Olenellus Zone’, c. 512 Ma) hypothesis, two lateral–dorsal grooves, uniquely preserved of Pennsylvania. These impressions are inferred to represent in Pelagiella atlantoides, are interpreted as sites of attach- clusters of chitinous chaetae, comparable to those borne by ment for a long left ctenidium and a short one, anteriorly annelid parapodia and some larval brachiopods. They pro- on the right. The orientation of Pelagiella and the asymme- vide an affirmative test in the early metazoan fossil record try of its gills, comparable to features of several living veti- of the inference, from phylogenetic analyses of living taxa, gastropods, nominate it as the earliest fossil mollusc known that chitinous chaetae are a shared early attribute of the to exhibit evidence of the developmental torsion character- Lophotrochozoa.
    [Show full text]
  • Feeding Strategy and Locomotion of Cambrian Hyolithides
    Available online at www.sciencedirect.com ScienceDirect Palaeoworld 27 (2018) 334–342 Feeding strategy and locomotion of Cambrian hyolithides a,∗ a b c,d b Hai-Jing Sun , Fang-Chen Zhao , Rong-Qin Wen , Han Zeng , Jin Peng a State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China b Resources and Environmental Engineering College, Guizhou University, Guiyang 550025, China c College of Earth Sciences, University of Chinese Academy of Sciences, No. 19 Yuquan Road, Beijing 100049, China d Department of Paleobiology, National Museum of Natural History, P.O. Box 37012, MRC-121, Washington, DC 20013-7012, USA Received 7 November 2017; received in revised form 8 March 2018; accepted 26 March 2018 Available online 3 April 2018 Abstract The Chengjiang (Cambrian Stage 3) and Balang (Cambrian Stage 4) Konservat-Lagerstätten of South China have produced abundant hyolithide hyoliths; however, little attention has been paid to their feeding strategy and the role it played in the ecosystem. Hyolithides preserved in coprolites from the Chengjiang Biota and associated with a Tuzoia carcass from the Balang Fauna reveal the fluid feces consuming and scavenging strategies of this group. Size distribution of hyolithides demonstrates that their dietary habit is ontogenetically dependent, with juveniles having ingested organic-rich material whereas adult food consumption was more likely by a variety of species-dependent methods The first discovery of hyolithides in association with locomotion traces and burrows indicates they were not only epibenthic vagrants, but also shallow horizontal burrowers. The new discoveries reported herein enhance our understanding of the feeding strategy and other behaviours of Cambrian hyolithides.
    [Show full text]