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Campli G, Volovych O, Kim K, Veldsman WP, Drage HB, Sheizaf I, Lynch S, Chipman AD, Daley AC, Robinson-Rechavi M, Waterhouse RM. The moulting arthropod: a complete genetic toolkit review. Biol Rev Camb Philos Soc 2024. [PMID: 39039636 DOI: 10.1111/brv.13123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 07/09/2024] [Accepted: 07/12/2024] [Indexed: 07/24/2024]
Abstract
Exoskeletons are a defining character of all arthropods that provide physical support for their segmented bodies and appendages as well as protection from the environment and predation. This ubiquitous yet evolutionarily variable feature has been instrumental in facilitating the adoption of a variety of lifestyles and the exploitation of ecological niches across all environments. Throughout the radiation that produced the more than one million described modern species, adaptability afforded by segmentation and exoskeletons has led to a diversity that is unrivalled amongst animals. However, because of the limited extensibility of exoskeleton chitin and cuticle components, they must be periodically shed and replaced with new larger ones, notably to accommodate the growing individuals encased within. Therefore, arthropods grow discontinuously by undergoing periodic moulting events, which follow a series of steps from the preparatory pre-moult phase to ecdysis itself and post-moult maturation of new exoskeletons. Each event represents a particularly vulnerable period in an arthropod's life cycle, so processes must be tightly regulated and meticulously executed to ensure successful transitions for normal growth and development. Decades of research in representative arthropods provide a foundation of understanding of the mechanisms involved. Building on this, studies continue to develop and test hypotheses on the presence and function of molecular components, including neuropeptides, hormones, and receptors, as well as the so-called early, late, and fate genes, across arthropod diversity. Here, we review the literature to develop a comprehensive overview of the status of accumulated knowledge of the genetic toolkit governing arthropod moulting. From biosynthesis and regulation of ecdysteroid and sesquiterpenoid hormones, to factors involved in hormonal stimulation responses and exoskeleton remodelling, we identify commonalities and differences, as well as highlighting major knowledge gaps, across arthropod groups. We examine the available evidence supporting current models of how components operate together to prepare for, execute, and recover from ecdysis, comparing reports from Chelicerata, Myriapoda, Crustacea, and Hexapoda. Evidence is generally highly taxonomically imbalanced, with most reports based on insect study systems. Biases are also evident in research on different moulting phases and processes, with the early triggers and late effectors generally being the least well explored. Our synthesis contrasts knowledge based on reported observations with reasonably plausible assumptions given current taxonomic sampling, and exposes weak assumptions or major gaps that need addressing. Encouragingly, advances in genomics are driving a diversification of tractable study systems by facilitating the cataloguing of putative genetic toolkits in previously under-explored taxa. Analysis of genome and transcriptome data supported by experimental investigations have validated the presence of an "ultra-conserved" core of arthropod genes involved in moulting processes. The molecular machinery has likely evolved with elaborations on this conserved pathway backbone, but more taxonomic exploration is needed to characterise lineage-specific changes and novelties. Furthermore, linking these to transformative innovations in moulting processes across Arthropoda remains hampered by knowledge gaps and hypotheses based on untested assumptions. Promisingly however, emerging from the synthesis is a framework that highlights research avenues from the underlying genetics to the dynamic molecular biology through to the complex physiology of moulting.
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Affiliation(s)
- Giulia Campli
- Department of Ecology and Evolution, Quartier UNIL-Sorge, Bâtiment Biophore, University of Lausanne, Lausanne, 1015, Switzerland
- SIB Swiss Institute of Bioinformatics, Quartier Sorge, Bâtiment Amphipôle, Lausanne, 1015, Switzerland
| | - Olga Volovych
- The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus - Givat Ram, Jerusalem, 9190401, Israel
| | - Kenneth Kim
- Department of Ecology and Evolution, Quartier UNIL-Sorge, Bâtiment Biophore, University of Lausanne, Lausanne, 1015, Switzerland
- SIB Swiss Institute of Bioinformatics, Quartier Sorge, Bâtiment Amphipôle, Lausanne, 1015, Switzerland
| | - Werner P Veldsman
- Department of Ecology and Evolution, Quartier UNIL-Sorge, Bâtiment Biophore, University of Lausanne, Lausanne, 1015, Switzerland
- SIB Swiss Institute of Bioinformatics, Quartier Sorge, Bâtiment Amphipôle, Lausanne, 1015, Switzerland
| | - Harriet B Drage
- Institute of Earth Sciences, Quartier UNIL-Mouline, Bâtiment Géopolis, University of Lausanne, Lausanne, 1015, Switzerland
| | - Idan Sheizaf
- The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus - Givat Ram, Jerusalem, 9190401, Israel
| | - Sinéad Lynch
- Institute of Earth Sciences, Quartier UNIL-Mouline, Bâtiment Géopolis, University of Lausanne, Lausanne, 1015, Switzerland
| | - Ariel D Chipman
- The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus - Givat Ram, Jerusalem, 9190401, Israel
| | - Allison C Daley
- Institute of Earth Sciences, Quartier UNIL-Mouline, Bâtiment Géopolis, University of Lausanne, Lausanne, 1015, Switzerland
| | - Marc Robinson-Rechavi
- Department of Ecology and Evolution, Quartier UNIL-Sorge, Bâtiment Biophore, University of Lausanne, Lausanne, 1015, Switzerland
- SIB Swiss Institute of Bioinformatics, Quartier Sorge, Bâtiment Amphipôle, Lausanne, 1015, Switzerland
| | - Robert M Waterhouse
- Department of Ecology and Evolution, Quartier UNIL-Sorge, Bâtiment Biophore, University of Lausanne, Lausanne, 1015, Switzerland
- SIB Swiss Institute of Bioinformatics, Quartier Sorge, Bâtiment Amphipôle, Lausanne, 1015, Switzerland
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2
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Corthésy N, Saleh F, Thomas C, Antcliffe JB, Daley AC. The effects of clays on bacterial community composition during arthropod decay. SWISS JOURNAL OF PALAEONTOLOGY 2024; 143:26. [PMID: 39006952 PMCID: PMC11236854 DOI: 10.1186/s13358-024-00324-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Accepted: 06/18/2024] [Indexed: 07/16/2024]
Abstract
Fossilization, or the transition of an organism from the biosphere to the geosphere, is a complex mechanism involving numerous biological and geological variables. Bacteria are one of the most significant biotic players to decompose organic matter in natural environments, early on during fossilization. However, bacterial processes are difficult to characterize as many different abiotic conditions can influence bacterial efficiency in degrading tissues. One potentially important variable is the composition and nature of the sediment on which a carcass is deposited after death. We experimentally examined this by decaying the marine shrimp Palaemon varians underwater on three different clay sediments. Samples were then analyzed using 16S ribosomal RNA sequencing to identify the bacterial communities associated with each clay system. Results show that samples decaying on the surface of kaolinite have a lower bacterial diversity than those decaying on the surface of bentonite and montmorillonite, which could explain the limited decay of carcasses deposited on this clay. However, this is not the only role played by kaolinite, as a greater proportion of gram-negative over gram-positive bacteria is observed in this system. Gram-positive bacteria are generally thought to be more efficient at recycling complex polysaccharides such as those forming the body walls of arthropods. This is the first experimental evidence of sediments shaping an entire bacterial community. Such interaction between sediments and bacteria might have contributed to arthropods' exquisite preservation and prevalence in kaolinite-rich Lagerstätten of the Cambrian Explosion. Supplementary Information The online version contains supplementary material available at 10.1186/s13358-024-00324-7.
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Affiliation(s)
- Nora Corthésy
- Institute of Earth Sciences, University of Lausanne, Géopolis, 1015 Lausanne, Switzerland
| | - Farid Saleh
- Institute of Earth Sciences, University of Lausanne, Géopolis, 1015 Lausanne, Switzerland
| | - Camille Thomas
- Institute of Geological Sciences, Oeschger Centre for Climate Research, University of Bern, Baltzerstrasse 1+3, 3012 Bern, Switzerland
- Department of Earth Sciences, University of Geneva, rue des Maraichers 13, 1205 Geneva, Switzerland
| | - Jonathan B Antcliffe
- Institute of Earth Sciences, University of Lausanne, Géopolis, 1015 Lausanne, Switzerland
| | - Allison C Daley
- Institute of Earth Sciences, University of Lausanne, Géopolis, 1015 Lausanne, Switzerland
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3
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Saleh F, Lustri L, Gueriau P, Potin GJM, Pérez-Peris F, Laibl L, Jamart V, Vite A, Antcliffe JB, Daley AC, Nohejlová M, Dupichaud C, Schöder S, Bérard E, Lynch S, Drage HB, Vaucher R, Vidal M, Monceret E, Monceret S, Lefebvre B. The Cabrières Biota (France) provides insights into Ordovician polar ecosystems. Nat Ecol Evol 2024; 8:651-662. [PMID: 38337049 PMCID: PMC11009115 DOI: 10.1038/s41559-024-02331-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 01/10/2024] [Indexed: 02/12/2024]
Abstract
Early Palaeozoic sites with soft-tissue preservation are predominantly found in Cambrian rocks and tend to capture past tropical and temperate ecosystems. In this study, we describe the diversity and preservation of the Cabrières Biota, a newly discovered Early Ordovician Lagerstätte from Montagne Noire, southern France. The Cabrières Biota showcases a diverse polar assemblage of both biomineralized and soft-bodied organisms predominantly preserved in iron oxides. Echinoderms are extremely scarce, while sponges and algae are abundantly represented. Non-biomineralized arthropod fragments are also preserved, along with faunal elements reminiscent of Cambrian Burgess Shale-type ecosystems, such as armoured lobopodians. The taxonomic diversity observed in the Cabrières Biota mixes Early Ordovician Lagerstätten taxa with Cambrian forms. By potentially being the closest Lagerstätte to the South Pole, the Cabrières Biota probably served as a biotic refuge amid the high-water temperatures of the Early Ordovician, and shows comparable ecological structuring to modern polar communities.
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Affiliation(s)
- Farid Saleh
- Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland.
| | - Lorenzo Lustri
- Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland
| | - Pierre Gueriau
- Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland
- Université Paris-Saclay, CNRS, ministère de la Culture, UVSQ, MNHN, Institut photonique d'analyse non-destructive européen des matériaux anciens, Saint-Aubin, France
| | - Gaëtan J-M Potin
- Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland
| | - Francesc Pérez-Peris
- Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland
- Department of Earth and Environmental Sciences, University of Iowa, Iowa City, IA, USA
| | - Lukáš Laibl
- Czech Academy of Sciences, Institute of Geology, Prague, Czech Republic
| | - Valentin Jamart
- Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland
| | - Antoine Vite
- Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland
- Université de Lyon, Université Claude Bernard Lyon 1, École Normale Supérieure de Lyon, CNRS, UMR5276, LGL-TPE, Villeurbanne, France
| | | | - Allison C Daley
- Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland
| | | | - Christophe Dupichaud
- Université de Lyon, Université Claude Bernard Lyon 1, École Normale Supérieure de Lyon, CNRS, UMR5276, LGL-TPE, Villeurbanne, France
| | | | - Emilie Bérard
- Synchrotron SOLEIL, L'Orme des merisiers, Gif-sur-Yvette, France
| | - Sinéad Lynch
- Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland
| | - Harriet B Drage
- Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland
| | - Romain Vaucher
- Institute of Earth Sciences, University of Lausanne, Lausanne, Switzerland
- Department of Earth Sciences, University of Geneva, Geneva, Switzerland
| | - Muriel Vidal
- Univ Brest, CNRS, Ifremer, Geo-Ocean, UMR 6538, Plouzané, France
| | - Eric Monceret
- Société d'Etudes Scientifiques de l'Aude, Carcassonne, France
| | - Sylvie Monceret
- Société d'Etudes Scientifiques de l'Aude, Carcassonne, France
| | - Bertrand Lefebvre
- Université de Lyon, Université Claude Bernard Lyon 1, École Normale Supérieure de Lyon, CNRS, UMR5276, LGL-TPE, Villeurbanne, France
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4
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Wu Y, Pates S, Pauly D, Zhang X, Fu D. Rapid growth in a large Cambrian apex predator. Natl Sci Rev 2024; 11:nwad284. [PMID: 38312385 PMCID: PMC10833464 DOI: 10.1093/nsr/nwad284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 10/09/2023] [Accepted: 11/02/2023] [Indexed: 02/06/2024] Open
Abstract
Despite the importance of ontogenetic data on early diverging euarthropods to our understanding of the ecology and evolution of past life, the data are distinctly lacking, as reconstructing life histories of fossil animals is often challenging. Here we report the growth trajectory of frontal appendages of the apex predator Amplectobelua symbrachiata, one of the most common radiodont arthropods from the early Cambrian Chengjiang biota (c. 520 Ma) of China. Analysis of 432 specimens (9.1-137.1 mm length; 1.3-25.6 mm height) reveals that appendages grew isometrically, with an estimated maximum size of the whole animal of c. 90 cm. Individuals grew rapidly compared to extant arthropods, as assessed using the electronic length-frequency analysis (ELEFAN) approach. Therefore, we show that the Cambrian apex predator A. symbrachiata was an extremely fast-growing arthropod, with an unusual life history strategy that formed as part of the escalatory 'arms race' that shaped the Cambrian explosion over 500 Ma.
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Affiliation(s)
- Yu Wu
- State Key Laboratory of Continental Dynamics and Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi’an 710069, China
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Stephen Pates
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Daniel Pauly
- Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Xingliang Zhang
- State Key Laboratory of Continental Dynamics and Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi’an 710069, China
- Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Dongjing Fu
- State Key Laboratory of Continental Dynamics and Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi’an 710069, China
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Park TYS, Nielsen ML, Parry LA, Sørensen MV, Lee M, Kihm JH, Ahn I, Park C, de Vivo G, Smith MP, Harper DAT, Nielsen AT, Vinther J. A giant stem-group chaetognath. SCIENCE ADVANCES 2024; 10:eadi6678. [PMID: 38170772 PMCID: PMC10796117 DOI: 10.1126/sciadv.adi6678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 12/01/2023] [Indexed: 01/05/2024]
Abstract
Chaetognaths, with their characteristic grasping spines, are the oldest known pelagic predators, found in the lowest Cambrian (Terreneuvian). Here, we describe a large stem chaetognath, Timorebestia koprii gen. et sp. nov., from the lower Cambrian Sirius Passet Lagerstätte, which exhibits lateral and caudal fins, a distinct head region with long antennae and a jaw apparatus similar to Amiskwia sagittiformis. Amiskwia has previously been interpreted as a total-group chaetognathiferan, as either a stem-chaetognath or gnathostomulid. We show that T. koprii shares a ventral ganglion with chaetognaths to the exclusion of other animal groups, firmly placing these fossils on the chaetognath stem. The large size (up to 30 cm) and gut contents in T. koprii suggest that early chaetognaths occupied a higher trophic position in pelagic food chains than today.
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Affiliation(s)
- Tae-Yoon S. Park
- Division of Earth Sciences, Korea Polar Research Institute, 26 Songdomirae-ro Yeonsu-gu, Incheon 21990, Republic of Korea
- University of Science and Technology, 217 Gajeong-ro, Daejeon 34113, Republic of Korea
| | - Morten Lunde Nielsen
- Division of Earth Sciences, Korea Polar Research Institute, 26 Songdomirae-ro Yeonsu-gu, Incheon 21990, Republic of Korea
- School of Earth Sciences, Palaeobiology Research Group, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
- British Geological Survey, Nicker Hill, Keyworth NG12 5GG, UK
| | - Luke A. Parry
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
| | | | - Mirinae Lee
- Division of Earth Sciences, Korea Polar Research Institute, 26 Songdomirae-ro Yeonsu-gu, Incheon 21990, Republic of Korea
| | - Ji-Hoon Kihm
- Division of Earth Sciences, Korea Polar Research Institute, 26 Songdomirae-ro Yeonsu-gu, Incheon 21990, Republic of Korea
- University of Science and Technology, 217 Gajeong-ro, Daejeon 34113, Republic of Korea
| | - Inhye Ahn
- Division of Earth Sciences, Korea Polar Research Institute, 26 Songdomirae-ro Yeonsu-gu, Incheon 21990, Republic of Korea
- University of Science and Technology, 217 Gajeong-ro, Daejeon 34113, Republic of Korea
| | - Changkun Park
- Division of Earth Sciences, Korea Polar Research Institute, 26 Songdomirae-ro Yeonsu-gu, Incheon 21990, Republic of Korea
| | - Giacinto de Vivo
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
| | - M. Paul Smith
- Oxford University Museum of Natural History, Parks Road, Oxford OX1 3PW, UK
| | - David A. T. Harper
- Palaeoecosystems Group, Department of Earth Sciences, Durham University, Durham DH1 3LE, UK
| | - Arne T. Nielsen
- Department of Geoscience and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, Copenhagen DK-1350, Denmark
| | - Jakob Vinther
- School of Earth Sciences, Palaeobiology Research Group, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
- School of Biological Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
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6
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Ostachuk A. A network analysis of early arthropod evolution and the potential of the primitive. Sci Rep 2024; 14:503. [PMID: 38177280 PMCID: PMC10766614 DOI: 10.1038/s41598-023-51019-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 12/29/2023] [Indexed: 01/06/2024] Open
Abstract
It is often thought that the primitive is simpler, and that the complex is generated from the simple by some process of self-assembly or self-organization, which ultimately consists of the spontaneous and fortuitous collision of elementary units. This idea is included in the Darwinian theory of evolution, to which is added the competitive mechanism of natural selection. To test this view, we studied the early evolution of arthropods. Twelve groups of arthropods belonging to the Burgess Shale, Orsten Lagerstätte, and extant primitive groups were selected, their external morphology abstracted and codified in the language of network theory. The analysis of these networks through different network measures (network parameters, topological descriptors, complexity measures) was used to carry out a Principal Component Analysis (PCA) and a Hierarchical Cluster Analysis (HCA), which allowed us to obtain an evolutionary tree with distinctive/novel features. The analysis of centrality measures revealed that these measures decreased throughout the evolutionary process, and led to the creation of the concept of evolutionary developmental potential. This potential, which measures the capacity of a morphological unit to generate changes in its surroundings, is concomitantly reduced throughout the evolutionary process, and demonstrates that the primitive is not simple but has a potential that unfolds during this process. This means for us the first empirical evolutionary evidence of our theory of evolution as a process of unfolding.
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Affiliation(s)
- Agustín Ostachuk
- Museo de La Plata (MLP), Universidad Nacional de La Plata (UNLP), Buenos Aires, Argentina.
- EVOLUTIO: A Research Center for Evolution and Development, Buenos Aires, Argentina.
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7
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O'Flynn RJ, Liu Y, Hou X, Mai H, Yu M, Zhuang S, Williams M, Guo J, Edgecombe GD. The early Cambrian Kylinxia zhangi and evolution of the arthropod head. Curr Biol 2023; 33:4006-4013.e2. [PMID: 37643622 DOI: 10.1016/j.cub.2023.08.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 06/01/2023] [Accepted: 08/04/2023] [Indexed: 08/31/2023]
Abstract
The early Cambrian Kylinxia zhangi occupies a pivotal position in arthropod evolution, branching from the euarthropod stem lineage between radiodonts (Anomalocaris and relatives) and "great-appendage" arthropods.1,2 Its combination of appendage and exoskeletal features is viewed as uniquely bridging the morphologies of so-called "lower" and "upper" stem-group euarthropods.3,4 Microtomographic study of new specimens of Kylinxia refines and corrects previous interpretation of head structures in this species. Phylogenetic analyses incorporating new data reinforce the placement of Kylinxia in the euarthropod stem group but support new hypotheses of head evolution. The head of Kylinxia is composed of six segments, as in extant mandibulates, e.g., insects.5 In Kylinxia, these are an anterior sclerite associated with an unpaired median eye and paired lateral eyes (thus three rather than five eyes as was previously described1), deutocerebral frontal-most appendages, and four pairs of biramous appendages (rather than two pairs of uniramous appendages). Phylogenetic trees suggest that a six-segmented head in the euarthropod crown group was already acquired by a common ancestor with Kylinxia. The segmental alignment and homology of spinose frontal-most appendages between radiodonts and upper stem-group euarthropods6,7,8,9,10 is bolstered by morphological similarities and inferred phylogenetic continuity between Kylinxia and other stem-group euarthropods.
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Affiliation(s)
- Robert J O'Flynn
- Yunnan Key Laboratory for Palaeobiology, Yunnan University, 650500 Kunming, China and School of Geography, Geology and the Environment, University of Leicester, University Road, Leicester, LE1 7RH, UK; Institute of Palaeontology, Yunnan University, 650500 Kunming, China; MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, 650500 Kunming, China
| | - Yu Liu
- Institute of Palaeontology, Yunnan University, 650500 Kunming, China; MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, 650500 Kunming, China; Chengjiang Fossil Museum of the Management Committee of the Chengjiang World Heritage Fossil Site, Chengjiang 652599, China.
| | - Xianguang Hou
- Institute of Palaeontology, Yunnan University, 650500 Kunming, China; MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, 650500 Kunming, China
| | - Huijuan Mai
- Institute of Palaeontology, Yunnan University, 650500 Kunming, China; MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, 650500 Kunming, China
| | - Mengxiao Yu
- Institute of Palaeontology, Yunnan University, 650500 Kunming, China; MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, 650500 Kunming, China
| | - Songling Zhuang
- Institute of Palaeontology, Yunnan University, 650500 Kunming, China; MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, 650500 Kunming, China
| | - Mark Williams
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, 650500 Kunming, China; School of Geography, Geology and the Environment, University of Leicester, University Road, Leicester, LE1 7RH, UK
| | - Jin Guo
- Institute of Palaeontology, Yunnan University, 650500 Kunming, China; MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, 650500 Kunming, China; Chengjiang Fossil Museum of the Management Committee of the Chengjiang World Heritage Fossil Site, Chengjiang 652599, China
| | - Gregory D Edgecombe
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, 650500 Kunming, China; The Natural History Museum, London SW7 5BD, UK.
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8
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Bernot JP, Owen CL, Wolfe JM, Meland K, Olesen J, Crandall KA. Major Revisions in Pancrustacean Phylogeny and Evidence of Sensitivity to Taxon Sampling. Mol Biol Evol 2023; 40:msad175. [PMID: 37552897 PMCID: PMC10414812 DOI: 10.1093/molbev/msad175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Revised: 06/14/2023] [Accepted: 06/19/2023] [Indexed: 08/10/2023] Open
Abstract
The clade Pancrustacea, comprising crustaceans and hexapods, is the most diverse group of animals on earth, containing over 80% of animal species and half of animal biomass. It has been the subject of several recent phylogenomic analyses, yet relationships within Pancrustacea show a notable lack of stability. Here, the phylogeny is estimated with expanded taxon sampling, particularly of malacostracans. We show small changes in taxon sampling have large impacts on phylogenetic estimation. By analyzing identical orthologs between two slightly different taxon sets, we show that the differences in the resulting topologies are due primarily to the effects of taxon sampling on the phylogenetic reconstruction method. We compare trees resulting from our phylogenomic analyses with those from the literature to explore the large tree space of pancrustacean phylogenetic hypotheses and find that statistical topology tests reject the previously published trees in favor of the maximum likelihood trees produced here. Our results reject several clades including Caridoida, Eucarida, Multicrustacea, Vericrustacea, and Syncarida. Notably, we find Copepoda nested within Allotriocarida with high support and recover a novel relationship between decapods, euphausiids, and syncarids that we refer to as the Syneucarida. With denser taxon sampling, we find Stomatopoda sister to this latter clade, which we collectively name Stomatocarida, dividing Malacostraca into three clades: Leptostraca, Peracarida, and Stomatocarida. A new Bayesian divergence time estimation is conducted using 13 vetted fossils. We review our results in the context of other pancrustacean phylogenetic hypotheses and highlight 15 key taxa to sample in future studies.
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Affiliation(s)
- James P Bernot
- Department of Invertebrate Zoology, US National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
| | - Christopher L Owen
- Systematic Entomology Laboratory, USDA-ARS, ℅ National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - Joanna M Wolfe
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - Kenneth Meland
- Department of Biology, University of Bergen, Bergen, Norway
| | - Jørgen Olesen
- Natural History Museum of Denmark, University of Copenhagen, Copenhagen, Denmark
| | - Keith A Crandall
- Department of Invertebrate Zoology, US National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
- Department of Biostatistics and Bioinformatics, Milken Institute School of Public Health, George Washington University, Washington, DC, USA
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9
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Pepato AR, Dos S Costa SG, Harvey MS, Klimov PB. One-way ticket to the blue: A large-scale, dated phylogeny revealed asymmetric land-to-water transitions in acariform mites (Acari: Acariformes). Mol Phylogenet Evol 2022; 177:107626. [PMID: 36096463 DOI: 10.1016/j.ympev.2022.107626] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 07/11/2022] [Accepted: 09/06/2022] [Indexed: 11/30/2022]
Abstract
Acariform mites are an ancient and megadiverse lineage that may have experienced a complex pattern of invasions into terrestrial and aquatic habitats. These among-realm transitions may relate to periods of turmoil in Earth's history or be simply results of uneven biodiversity patterns across habitats. Here, we inferred a dated, representative acariform phylogeny (five genes, 9,200 bp aligned, 367 terminals belonging to 150 ingroup plus 15 outgroup families, 23 fossil calibration points) which was used to infer transitions between marine/freshwater/terrestrial habitats. We detected four unambiguous transitions from terrestrial to freshwater habitats (Hydrozetes, Naiadacarus, Fusohericia, Afronothrus, Homocaligus); one from freshwater to marine (Pontarachnidae), and four from marine to brackish or freshwater transitions (all among Halacaridae: Acarothrix; Halacarellus petiti; Copidognathus sp.; clade Limnohalacarus + Soldanellonyx + Porohalacarus + Porolohmannella). One transition to the sea was inferred ambiguously with respect to the ancestor being either terrestrial or freshwater (Hyadesiidae), and another must be most carefully examined by adding potential related taxa (Selenoribatidae + Fortuyniidae). Finally, we inferred a single, remarkable transition from aquatic to terrestrial habitats involving early evolution of the large and ecologically diverse lineage: the ancestor of the Halacaridae + Parasitengona clade was probably freshwater given our dataset, thus making terrestrial Parasitengona secondarily terrestrial. Overall, our results suggested a strong asymmetry in environmental transitions: the majority occurred from terrestrial to aquatic habitats. This asymmetry is probably linked to mites' biological properties and uneven biodiversity patterns across habitats rather than Earth's geological history. Since the land holds more acariform diversity than water habitats, a shift from the former is more likely than from the latter. We inferred the following relationships: alicid endeostigmatid + eriophyoid (Alycidae, (Nanorchestidae, (Nematalycidae, Eriophyoidea))) being sister group to the remaining Acariformes: (proteonematalycid Endeostigmata, alicorhagiid Endeostigmata, Trombidiformes, Oribatida (including Astigmata)). Trombidiform relationships had several novel rearrangements: (i) traditional Eupodina lacked support for the inclusion of Bdelloidea; (ii) Teneriffidae, traditionally placed among Anystina, was consistently recovered in a clade including Heterostigmata in Eleutherengona; (iii) several lineages, such as Adamystidae, Paratydeidae, Caeculidae and Erythracaridae, were recovered in a large clade along other Anystina and Eleutherengona, suggesting single origins of several fundamental character states, such as the reduction of the cheliceral fixed digit and development of the palpal thumb-claw complex.
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Affiliation(s)
- Almir R Pepato
- Universidade Federal de Minas Gerais, Instituto de Ciências Biológicas, Departamento de Zoologia, Laboratório de Sistemática e Evolução de Ácaros Acariformes, Av. Antonio Carlos, 6627, Pampulha, Belo Horizonte - MG ZIP: 31270-901, Brazil; Tyumen State University, X-BIO Institute, 10 Semakova Str., 625003 Tyumen, Russia.
| | - Samuel G Dos S Costa
- Universidade Federal de Minas Gerais, Instituto de Ciências Biológicas, Departamento de Zoologia, Laboratório de Sistemática e Evolução de Ácaros Acariformes, Av. Antonio Carlos, 6627, Pampulha, Belo Horizonte - MG ZIP: 31270-901, Brazil
| | - Mark S Harvey
- Collections & Research, Western Australian Museum, Welshpool, Western Australia 6106, Australia; School of Biological Sciences, University of Western Australia, Crawley, Western Australia 6009, Australia
| | - Pavel B Klimov
- Purdue University, Lilly Hall of Life Sciences, G-226, 915 W State St, West Lafayette, IN 47907, United States; Tyumen State University, X-BIO Institute, 10 Semakova Str., 625003 Tyumen, Russia
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10
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Pates S, Botting JP, Muir LA, Wolfe JM. Ordovician opabiniid-like animals and the role of the proboscis in euarthropod head evolution. Nat Commun 2022; 13:6969. [PMID: 36379946 PMCID: PMC9666559 DOI: 10.1038/s41467-022-34204-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 10/18/2022] [Indexed: 11/16/2022] Open
Abstract
A crucial step in the evolution of Euarthropoda (chelicerates, myriapods, pancrustaceans) was the transition between fossil groups that possessed frontal appendages innervated by the first segment of the brain (protocerebrum), and living groups with a protocerebral labrum and paired appendages innervated by the second brain segment (deutocerebrum). Appendage homologies between the groups are controversial. Here we describe two specimens of opabiniid-like euarthropods, each bearing an anterior proboscis (a fused protocerebral appendage), from the Middle Ordovician Castle Bank Biota, Wales, UK. Phylogenetic analyses support a paraphyletic grade of stem-group euarthropods with fused protocerebral appendages and a posterior-facing mouth, as in the iconic Cambrian panarthropod Opabinia. These results suggest that the labrum may have reduced from an already-fused proboscis, rather than a pair of arthropodized appendages. If some shared features between the Castle Bank specimens and radiodonts are considered convergent rather than homologous, phylogenetic analyses retrieve them as opabiniids, substantially extending the geographic and temporal range of Opabiniidae.
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Affiliation(s)
- Stephen Pates
- grid.5335.00000000121885934Department of Zoology, University of Cambridge, Cambridge, UK
| | - Joseph P. Botting
- grid.9227.e0000000119573309Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China ,grid.422296.90000 0001 2293 9551Department of Natural Sciences, Amgueddfa Cymru—National Museum Wales, Cardiff, UK
| | - Lucy A. Muir
- grid.422296.90000 0001 2293 9551Department of Natural Sciences, Amgueddfa Cymru—National Museum Wales, Cardiff, UK
| | - Joanna M. Wolfe
- grid.38142.3c000000041936754XMuseum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA USA
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11
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Vargas‐Parra EE, Hopkins MJ. Modularity in the trilobite head consistent with the hypothesized segmental origin of the eyes. Evol Dev 2022; 24:177-188. [PMID: 36111749 PMCID: PMC9786538 DOI: 10.1111/ede.12418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 07/06/2022] [Accepted: 08/18/2022] [Indexed: 12/30/2022]
Abstract
The trilobite head served multiple functions and was composed of several fused segments. Yet, the underlying organization of the trilobite head, and whether patterns are conserved across trilobites, remains unclear. Modeling the head as being composed of modules, or subunits that vary and thus have the potential to evolve semi-independently can reveal underlying patterns of organization. Hypotheses of modular organization based on the comparative developmental biology of arthropods were evaluated using geometric morphometrics. Two-dimensional (semi)landmark datasets collected from the cranidia of two Ordovician trilobite species, Calyptaulax annulata (Phacopida) and Cloacaspis senilis (Olenida sensu Adrain, 2011) were analyzed. The degree and pattern of modularity were assessed using the covariance ratio (CR), which compares the covariation within putative modules to the covariation between them, and the fit of different models was compared using an effect size measure derived from the CR. When treating the eyes as a distinct module, the best modular hypothesis identified for C. annulata shows the eyes and anteriormost region of the head integrated as a single module. The best modular hypotheses for C. senilis are more complex but the eyes still covary mostly strongly with the anterior part of the head. The latter is also the case for all other well-supported models for both species. These results can be interpreted as a developmental signal corresponding to the anteriormost ocular segment of early arthropods that is retained throughout development, despite any likely selective pressures related to functional needs.
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Affiliation(s)
| | - Melanie J. Hopkins
- Division of PaleontologyAmerican Museum of Natural HistoryNew YorkNew YorkUSA
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12
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Saleh F, Ma X, Guenser P, Mángano MG, Buatois LA, Antcliffe JB. Probability-based preservational variations within the early Cambrian Chengjiang biota (China). PeerJ 2022; 10:e13869. [PMID: 36032952 PMCID: PMC9415357 DOI: 10.7717/peerj.13869] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 07/19/2022] [Indexed: 01/18/2023] Open
Abstract
The Chengjiang biota (Yunnan Province, China) is a treasure trove of soft-bodied animal fossils from the earliest stages of the Cambrian explosion. The mechanisms contributing to its unique preservation, known as the Burgess Shale-type preservation, are well understood. However, little is known about the preservation differences between various animal groups within this biota. This study compares tissue-occurrence data of 11 major animal groups in the Chengjiang biota using a probabilistic methodology. The fossil-based data from this study is compared to previous decay experiments. This shows that all groups are not equally preserved with some higher taxa more likely to preserve soft tissues than others. These differences in fossil preservation between taxa can be explained by the interaction of biological and environmental characteristics. A bias also results from differential taxonomic recognition, as some taxa are easily recognized from even poorly preserved fragments while other specimens are difficult to assign to higher taxa even with exquisite preservation.
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Affiliation(s)
- Farid Saleh
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, China,Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming, China
| | - Xiaoya Ma
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, China,Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming, China,Centre for Ecology and Conservation, University of Exeter, Penryn, United Kingdom
| | - Pauline Guenser
- University Bordeaux, CNRS, Bordeaux INP, EPOC, UMR5805, Pessac, France
| | - M. Gabriela Mángano
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Canada
| | - Luis A. Buatois
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, Canada
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13
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Aria C. The origin and early evolution of arthropods. Biol Rev Camb Philos Soc 2022; 97:1786-1809. [PMID: 35475316 DOI: 10.1111/brv.12864] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 04/12/2022] [Accepted: 04/14/2022] [Indexed: 12/18/2022]
Abstract
The rise of arthropods is a decisive event in the history of life. Likely the first animals to have established themselves on land and in the air, arthropods have pervaded nearly all ecosystems and have become pillars of the planet's ecological networks. Forerunners of this saga, exceptionally well-preserved Palaeozoic fossils recently discovered or re-discovered using new approaches and techniques have elucidated the precocious appearance of extant lineages at the onset of the Cambrian explosion, and pointed to the critical role of the plankton and hard integuments in early arthropod diversification. The notion put forward at the beginning of the century that the acquisition of extant arthropod characters was stepwise and represented by the majority of Cambrian fossil taxa is being rewritten. Although some key traits leading to Euarthropoda are indeed well documented along a diversified phylogenetic stem, this stem led to several speciose and ecologically diverse radiations leaving descendants late into the Palaeozoic, and a large part, if not all of the Cambrian euarthropods can now be placed on either of the two extant lineages: Mandibulata and Chelicerata. These new observations and discoveries have altered our view on the nature and timing of the Cambrian explosion and clarified diagnostic characters at the origin of extant arthropods, but also raised new questions, especially with respect to cephalic plasticity. There is now strong evidence that early arthropods shared a homologous frontalmost appendage, coined here the cheira, which likely evolved into antennules and chelicerae, but other aspects, such as brain and labrum evolution, are still subject to active debate. The early evolution of panarthropods was generally driven by increased mastication and predation efficiency and sophistication, but a wealth of recent studies have also highlighted the prevalent role of suspension-feeding, for which early panarthropods developed their own adaptive feedback through both specialized appendages and the diversification of small, morphologically differentiated larvae. In a context of general integumental differentiation and hardening across Cambrian metazoans, arthrodization of body and limbs notably prompted two diverging strategies of basipod differentiation, which arguably became founding criteria in the divergence of total-groups Mandibulata and Chelicerata. The kinship of trilobites and their relatives remains a source of disagreement, but a recent topological solution, termed the 'deep split', could embed Artiopoda as sister taxa to chelicerates and constitute definitive support for Arachnomorpha. Although Cambrian fossils have been critical to all these findings, data of exceptional quality have also been accumulating from other Palaeozoic Konservat-Lagerstätten, and a better integration of this information promises a much more complete and elaborate picture of early arthropod evolution in the near future. From the broader perspective of a total-evidence approach to the understanding of life's history, and despite persisting systematic debates and new interpretative challenges, various advances based on palaeontological evidence open the prospect of finally using the full potential of the most diverse animal phylum to investigate macroevolutionary patterns and processes.
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Affiliation(s)
- Cédric Aria
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Palaeoenvironment, Chinese Academy of Sciences, Nanjing, 210008, P. R. China.,Shaanxi Key Laboratory of Early Life and Environments, Northwest University, Xi'an, 710069, P.R. China
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14
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Saleh F, Guenser P, Gibert C, Balseiro D, Serra F, Waisfeld BG, Antcliffe JB, Daley AC, Mángano MG, Buatois LA, Ma X, Vizcaïno D, Lefebvre B. Contrasting Early Ordovician assembly patterns highlight the complex initial stages of the Ordovician Radiation. Sci Rep 2022; 12:3852. [PMID: 35264650 PMCID: PMC8907272 DOI: 10.1038/s41598-022-07822-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 02/25/2022] [Indexed: 11/09/2022] Open
Abstract
The Early Ordovician is a key interval for our understanding of the evolution of life on Earth as it lays at the transition between the Cambrian Explosion and the Ordovician Radiation and because the fossil record of the late Cambrian is scarce. In this study, assembly processes of Early Ordovician trilobite and echinoderm communities from the Central Anti-Atlas (Morocco), the Montagne Noire (France), and the Cordillera Oriental (Argentina) are explored. The results show that dispersal increased diachronically in trilobite communities during the Early Ordovician. Dispersal did not increase for echinoderms. Dispersal was most probably proximally triggered by the planktic revolution, the fall in seawater temperatures, changes in oceanic circulation, with an overall control by tectonic frameworks and phylogenetic constraints. The diachronous increase in dispersal within trilobite communities in the Early Ordovician highlights the complexity of ecosystem structuring during the early stages of the Ordovician Radiation. As Early Ordovician regional dispersal was followed by well-documented continental dispersal in the Middle/Late Ordovician, it is possible to consider that alongside a global increase in taxonomic richness, the Ordovician Radiation is also characterized by a gradual increase in dispersal.
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Affiliation(s)
- Farid Saleh
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, China. .,MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Institute of Palaeontology, Yunnan University, Kunming, China.
| | - Pauline Guenser
- Université Claude Bernard Lyon 1, CNRS, UMR5023, LEHNA, Université de Lyon, 69622, Villeurbanne, France
| | - Corentin Gibert
- Laboratoire de la Préhistoire à l'Actuel: Culture, Environnement et Anthropologie (PACEA, UMR 5199 CNRS, INEE), University of Bordeaux, Bordeaux, France.
| | - Diego Balseiro
- Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina.,Centro de Investigaciones en Ciencias de la Tierra (CICTERRA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Vélez Sarsfield 1611, CP X5016GCA, Córdoba, Argentina
| | - Fernanda Serra
- Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina.,Centro de Investigaciones en Ciencias de la Tierra (CICTERRA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Vélez Sarsfield 1611, CP X5016GCA, Córdoba, Argentina
| | - Beatriz G Waisfeld
- Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina.,Centro de Investigaciones en Ciencias de la Tierra (CICTERRA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Vélez Sarsfield 1611, CP X5016GCA, Córdoba, Argentina
| | - Jonathan B Antcliffe
- Institute of Earth Sciences, University of Lausanne, Géopolis, 1015, Lausanne, Switzerland
| | - Allison C Daley
- Institute of Earth Sciences, University of Lausanne, Géopolis, 1015, Lausanne, Switzerland
| | - M Gabriela Mángano
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5E2, Canada
| | - Luis A Buatois
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK, S7N 5E2, Canada
| | - Xiaoya Ma
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, China. .,MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Institute of Palaeontology, Yunnan University, Kunming, China. .,Centre for Ecology and Conservation, University of Exeter, Penryn, UK.
| | | | - Bertrand Lefebvre
- Université Claude Bernard Lyon1, École Normale Supérieure de Lyon, CNRS, UMR5276, LGL-TPE, Université de Lyon, Villeurbanne, France
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15
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Pates S, Wolfe JM, Lerosey-Aubril R, Daley AC, Ortega-Hernández J. New opabiniid diversifies the weirdest wonders of the euarthropod stem group. Proc Biol Sci 2022; 289:20212093. [PMID: 35135344 PMCID: PMC8826304 DOI: 10.1098/rspb.2021.2093] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Once considered 'weird wonders' of the Cambrian, the emblematic Burgess Shale animals Anomalocaris and Opabinia are now recognized as lower stem-group euarthropods and have provided crucial data for constraining the polarity of key morphological characters in the group. Anomalocaris and its relatives (radiodonts) had worldwide distribution and survived until at least the Devonian. However, despite intense study, Opabinia remains the only formally described opabiniid to date. Here we reinterpret a fossil from the Wheeler Formation of Utah as a new opabiniid, Utaurora comosa nov. gen. et sp. By visualizing the sample of phylogenetic topologies in treespace, our results fortify support for the position of U. comosa beyond the nodal support traditionally applied. Our phylogenetic evidence expands opabiniids to multiple Cambrian stages. Our results underscore the power of treespace visualization for resolving imperfectly preserved fossils and expanding the known diversity and spatio-temporal ranges within the euarthropod lower stem group.
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Affiliation(s)
- Stephen Pates
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA.,Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Joanna M Wolfe
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
| | - Rudy Lerosey-Aubril
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
| | - Allison C Daley
- Institute of Earth Sciences, University of Lausanne, Géopolis, 1015 Lausanne, Switzerland
| | - Javier Ortega-Hernández
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
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16
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Fournier GP, Parsons CW, Cutts EM, Tamre E. Standard Candles for Dating Microbial Lineages. Methods Mol Biol 2022; 2569:41-74. [PMID: 36083443 DOI: 10.1007/978-1-0716-2691-7_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Molecular clock analyses are challenging for microbial phylogenies, due to a lack of fossil calibrations that can reliably provide absolute time constraints. An alternative source of temporal constraints for microbial groups is provided by the inheritance of proteins that are specific for the utilization of eukaryote-derived substrates, which have often been dispersed across the Tree of Life via horizontal gene transfer. In particular, animal, algal, and plant-derived substrates are often produced by groups with more precisely known divergence times, providing an older-bound on their availability within microbial environments. Therefore, these ages can serve as "standard candles" for dating microbial groups across the Tree of Life, expanding the reach of informative molecular clock investigations. Here, we formally develop the concept of substrate standard candles and describe how they can be propagated and applied using both microbial species trees and individual gene family phylogenies. We also provide detailed evaluations of several candidate standard candles and discuss their suitability in light of their often complex evolutionary and metabolic histories.
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Affiliation(s)
- Gregory P Fournier
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Chris W Parsons
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Elise M Cutts
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Erik Tamre
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
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17
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Jiao DG, Pates S, Lerosey-Aubril R, Ortega-Hernández J, Yang J, Lan T, Zhang XG. New multipodomerous appendages of stem-group euarthropods from the Cambrian (Stage 4) Guanshan Konservat-Lagerstätte. ROYAL SOCIETY OPEN SCIENCE 2021; 8:211134. [PMID: 34804574 PMCID: PMC8580442 DOI: 10.1098/rsos.211134] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 10/04/2021] [Indexed: 05/13/2023]
Abstract
Stem-group euarthropods are important for understanding the early evolutionary and ecological history of the most species-rich animal phylum on Earth. Of particular interest are fossil taxa that occupy a phylogenetic position immediately crownwards of radiodonts, for this part of the euarthropod tree is associated with the appearance of several morphological features that characterize extant members of the group. Here, we report two new euarthropods from the Cambrian Stage 4 Guanshan Biota of South China. The fuxianhuiid Alacaris? sp. is represented by isolated appendages composed of a gnathobasic protopodite and an endite-bearing endopod of at least 20 podomeres. This material represents the youngest occurrence of the family Chengjiangocarididae, and its first record outside the Chengjiang and Xiaoshiba biotas. We also describe Lihuacaris ferox gen. et sp. nov. based on well-preserved and robust isolated appendages. Lihuacaris ferox exhibits an atypical combination of characters including an enlarged rectangular base, 11 endite-bearing podomeres and a hypertrophied distal element bearing 8-10 curved spines. Alacaris? sp. appendages display adaptations for macrophagy. Lihuacaris ferox appendages resemble the frontal appendages of radiodonts, as well as the post-oral endopods of chengjiangocaridid fuxianhuids and other deuteropods with well-documented raptorial/predatory habits. Lihuacaris ferox contributes towards the record of endemic biodiversity in the Guanshan Biota.
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Affiliation(s)
- De-guang Jiao
- Yuxi Normal University, Kunming, 134 Phoenix Road, Yuxi, Yunnan 653100, People's Republic of China
- Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, People's Republic of China
| | - Stephen Pates
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Rudy Lerosey-Aubril
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Javier Ortega-Hernández
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Jie Yang
- Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, People's Republic of China
| | - Tian Lan
- College of Resources and Environmental Engineering, Guizhou University, Guiyang 550003, People's Republic of China
| | - Xi-guang Zhang
- Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, People's Republic of China
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18
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Beavan AJS, Pisani D, Donoghue PCJ. Diversification dynamics of total-, stem-, and crown-groups are compatible with molecular clock estimates of divergence times. SCIENCE ADVANCES 2021; 7:eabf2257. [PMID: 34117058 PMCID: PMC8195484 DOI: 10.1126/sciadv.abf2257] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 04/28/2021] [Indexed: 05/05/2023]
Abstract
Molecular evolutionary time scales are expected to predate the fossil evidence, but, particularly for major evolutionary radiations, they can imply extremely protracted stem lineages predating the origin of living clades, leading to claims of systematic overestimation of divergence times. We use macroevolutionary birth-death models to describe the range of total-group and crown-group ages expected under constant rates of speciation and extinction. We extend current predictions on origination times for crown- and total-groups, and extinction of stem-groups, demonstrating that there is broad variance in these predictions. Under constant rates of speciation and extinction, we show that the distribution of expected arthropod total-group ages is consistent with molecular clock estimates. The fossil record cannot be read literally, and our results preclude attempts to interpret the antiquity of clades based on the co-occurrence of stem- and crown-representatives.
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Affiliation(s)
- Alan J S Beavan
- School of Biological Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK.
| | - Davide Pisani
- School of Biological Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK.
- School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Philip C J Donoghue
- School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK.
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19
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Budd GE. The origin and evolution of the euarthropod labrum. ARTHROPOD STRUCTURE & DEVELOPMENT 2021; 62:101048. [PMID: 33862532 DOI: 10.1016/j.asd.2021.101048] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 02/24/2021] [Accepted: 02/25/2021] [Indexed: 05/16/2023]
Abstract
A widely (although not universally) accepted model of arthropod head evolution postulates that the labrum, a structure seen in almost all living euarthropods, evolved from an anterior pair of appendages homologous to the frontal appendages of onychophorans. However, the implications of this model for the interpretation of fossil arthropods have not been fully integrated into reconstructions of the euarthropod stem group, which remains in a state of some disorder. Here I review the evidence for the nature and evolution of the labrum from living taxa, and reconsider how fossils should be interpreted in the light of this. Identification of the segmental identity of head appendage in fossil arthropods remains problematic, and often rests ultimately on unproven assertions. New evidence from the Cambrian stem-group euarthropod Parapeytoia is presented to suggest that an originally protocerebral appendage persisted well up into the upper stem-group of the euarthropods, which prompts a re-evaluation of widely-accepted segmental homologies and the interpretation of fossil central nervous systems. Only a protocerebral brain was implicitly present in a large part of the euarthropod stem group, and the deutocerebrum must have been a relatively late addition.
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Affiliation(s)
- Graham E Budd
- Department of Earth Sciences, Palaeobiology Programme, Uppsala University, Villavägen 16, Uppsala, SE 752 36, Sweden.
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20
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Hildenbrand A, Austermann G, Fuchs D, Bengtson P, Stinnesbeck W. A potential cephalopod from the early Cambrian of eastern Newfoundland, Canada. Commun Biol 2021; 4:388. [PMID: 33758350 PMCID: PMC7987959 DOI: 10.1038/s42003-021-01885-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 02/19/2021] [Indexed: 01/14/2023] Open
Abstract
Although an early Cambrian origin of cephalopods has been suggested by molecular studies, no unequivocal fossil evidence has yet been presented. Septate shells collected from shallow-marine limestone of the lower Cambrian (upper Terreneuvian, c. 522 Ma) Bonavista Formation of southeastern Newfoundland, Canada, are here interpreted as straight, elongate conical cephalopod phragmocones. The material documented here may push the origin of cephalopods back in time by about 30 Ma to an unexpected early stage of the Cambrian biotic radiation of metazoans, i.e. before the first occurrence of euarthropods.
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Affiliation(s)
- Anne Hildenbrand
- grid.7700.00000 0001 2190 4373Institute of Earth Sciences, Heidelberg University, Im Neuenheimer Feld, Heidelberg, Germany
| | - Gregor Austermann
- grid.7700.00000 0001 2190 4373Institute of Earth Sciences, Heidelberg University, Im Neuenheimer Feld, Heidelberg, Germany
| | - Dirk Fuchs
- Bavarian State Collection for Paleontology and Geology, Richard-Wagner-Straße, Munich, Germany
| | - Peter Bengtson
- grid.7700.00000 0001 2190 4373Institute of Earth Sciences, Heidelberg University, Im Neuenheimer Feld, Heidelberg, Germany
| | - Wolfgang Stinnesbeck
- grid.7700.00000 0001 2190 4373Institute of Earth Sciences, Heidelberg University, Im Neuenheimer Feld, Heidelberg, Germany
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21
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Pates S, Lerosey-Aubril R, Daley AC, Kier C, Bonino E, Ortega-Hernández J. The diverse radiodont fauna from the Marjum Formation of Utah, USA (Cambrian: Drumian). PeerJ 2021; 9:e10509. [PMID: 33552709 PMCID: PMC7821760 DOI: 10.7717/peerj.10509] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 11/16/2020] [Indexed: 11/20/2022] Open
Abstract
Radiodonts have long been known from Cambrian deposits preserving non-biomineralizing organisms. In Utah, the presence of these panarthropods in the Spence and Wheeler (House Range and Drum Mountains) biotas is now well-documented. Conversely, radiodont occurrences in the Marjum Formation have remained scarce. Despite the large amount of work undertaken on its diverse fauna, only one radiodont (Peytoia) has been reported from the Marjum Biota. In this contribution we quadruple the known radiodont diversity of the Marjum fauna, with the description of the youngest members of two genera, Caryosyntrips and Pahvantia, and that of a new taxon Buccaspinea cooperi gen. et sp. nov. This new taxon can be identified from its large oral cone bearing robust hooked teeth with one, two, or three cusps, and by the unique endite morphology and organisation of its frontal appendages. Appendages of at least 12 podomeres bear six recurved plate-like endites proximal to up to four spiniform distal endites. Pahvantia hastata specimens from the Marjum Formation are particularly large, but otherwise morphologically indistinguishable from the carapace elements of this species found in the Wheeler Formation. One of the two new Caryosyntrips specimens can be confidently assigned to C. camurus. The other bears the largest spines relative to appendage length recorded for this genus, and possesses endites of variable size and unequal spacing, making its taxonomic assignment uncertain. Caryosyntrips, Pahvantia, and Peytoia are all known from the underlying Wheeler Formation, whereas isolated appendages from the Spence Shale and the Wheeler Formation, previously assigned to Hurdia, are tentatively reidentified as Buccaspinea. Notably, none of these four genera occurs in the overlying Weeks Formation, providing supporting evidence of a faunal restructuring around the Drumian-Guzhangian boundary. The description of three additional nektonic taxa from the Marjum Formation further documents the higher relative proportion of free-swimming species in this biota compared to those of the Wheeler and Weeks Lagerstätten. This could be related to a moderate deepening of the basin and/or changing regional ocean circulation at this time.
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Affiliation(s)
- Stephen Pates
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - Rudy Lerosey-Aubril
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - Allison C. Daley
- Institut des sciences de la Terre (ISTE), Université de Lausanne, Lausanne, Vaud, Switzerland
| | - Carlo Kier
- Back to the Past Museum, Carretera Cancún, Quintana Roo, Mexico
| | - Enrico Bonino
- Back to the Past Museum, Carretera Cancún, Quintana Roo, Mexico
| | - Javier Ortega-Hernández
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
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Zeng H, Zhao F, Niu K, Zhu M, Huang D. An early Cambrian euarthropod with radiodont-like raptorial appendages. Nature 2020; 588:101-105. [PMID: 33149303 DOI: 10.1038/s41586-020-2883-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 08/14/2020] [Indexed: 12/19/2022]
Abstract
Resolving the early evolution of euarthropods is one of the most challenging problems in metazoan evolution1,2. Exceptionally preserved fossils from the Cambrian period have contributed important palaeontological data to deciphering this evolutionary process3,4. Phylogenetic studies have resolved Radiodonta (also known as anomalocaridids) as the closest group to all euarthropods that have frontalmost appendages on the second head segment (Deuteropoda)5-9. However, the interrelationships among major Cambrian euarthropod groups remain disputed1,2,4,7, which impedes our understanding of the evolutionary gap between Radiodonta and Deuteropoda. Here we describe Kylinxia zhangi gen. et. sp. nov., a euarthropod from the early Cambrian Chengjiang biota of China. Kylinxia possesses not only deuteropod characteristics such as a fused head shield, a fully arthrodized trunk and jointed endopodites, but also five eyes (as in Opabinia) as well as radiodont-like raptorial frontalmost appendages. Our phylogenetic reconstruction recovers Kylinxia as a transitional taxon that bridges Radiodonta and Deuteropoda. The most basal deuteropods are retrieved as a paraphyletic lineage that features plesiomorphic raptorial frontalmost appendages and includes Kylinxia, megacheirans, panchelicerates, 'great-appendage' bivalved euarthropods and isoxyids. This phylogenetic topology supports the idea that the radiodont and megacheiran frontalmost appendages are homologous, that the chelicerae of Chelicerata originated from megacheiran great appendages and that the sensorial antennae in Mandibulata derived from ancestral raptorial forms. Kylinxia thus provides important insights into the phylogenetic relationships among early euarthropods, the evolutionary transformations and disparity of frontalmost appendages, and the origin of crucial evolutionary innovations in this clade.
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Affiliation(s)
- Han Zeng
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China.,Center for Excellence in Life and Palaeoenvironment, Chinese Academy of Sciences, Nanjing, China.,Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - Fangchen Zhao
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China. .,Center for Excellence in Life and Palaeoenvironment, Chinese Academy of Sciences, Nanjing, China. .,College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China.
| | - Kecheng Niu
- Yingliang Stone Natural History Museum, Nan'an, China
| | - Maoyan Zhu
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China.,Center for Excellence in Life and Palaeoenvironment, Chinese Academy of Sciences, Nanjing, China.,College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Diying Huang
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China. .,Center for Excellence in Life and Palaeoenvironment, Chinese Academy of Sciences, Nanjing, China.
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23
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Edgecombe GD. Arthropod Origins: Integrating Paleontological and Molecular Evidence. ANNUAL REVIEW OF ECOLOGY, EVOLUTION, AND SYSTEMATICS 2020. [DOI: 10.1146/annurev-ecolsys-011720-124437] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Phylogenomics underpins a stable and mostly well-resolved hypothesis for the interrelationships of extant arthropods. Exceptionally preserved fossils are integrated into this framework by coding their morphological characters, as exemplified by total-evidence dating approaches that treat fossils as dated tips in analyses numerically dominated by molecular data. Cambrian fossils inform on the sequence of character acquisition in the arthropod stem group and in the stems of its main extant clades. The arthropod head problem incorporates unique appendage combinations and remains of the nervous system in fossils into a scheme mostly based on neuroanatomy and Hox expression domains for extant forms. Molecular estimates of arthropod origins in the Cryogenian or Ediacaran predate a coherent picture from the arthropod fossil record, which commences as trace fossils in the earliest Cambrian. Probabilistic morphological clock analysis of trilobites, which exemplify the earliest arthropod body fossils, supports a Cambrian origin, without the need to posit an unfossilized Ediacaran history.
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Affiliation(s)
- Gregory D. Edgecombe
- Department of Earth Sciences, The Natural History Museum, London SW7 5BD, United Kingdom
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24
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Haug C. The evolution of feeding within Euchelicerata: data from the fossil groups Eurypterida and Trigonotarbida illustrate possible evolutionary pathways. PeerJ 2020. [DOI: 10.7717/peerj.9696] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
When the evolution of Euarthropoda is discussed, often the lineage of Chelicerata s. str. is assumed to be the more ‘primitive’ or ‘basal’ part of the tree, especially when compared to the other major lineage, Mandibulata. This claimed primitiveness is (at least partly) based on the assumption that different morphological structures are still in an ancestral state and did not evolve any further. One of these sets of structures is the feeding apparatus, which has been stated to be highly advanced in Mandibulata, but not ‘properly’ developed, or at least not to such a high degree, within Chelicerata s. str. In this study, I reinvestigate the feeding apparatus of different ingroups of Euchelicerata, with a focus on assumed ‘primitive’ groups such as Eurypterida and Trigonotarbida. The basis of this study is a large amount of material from different museum collections, with fossils with the entire feeding apparatuses being exceptionally well preserved. Based on high-resolution micro-photography and three-dimensional imaging, it is possible to resolve fine details of the feeding apparatuses. The results make clear that the feeding apparatuses of different ingroups of Euchelicerata are highly specialised and often possess morphological structures comparable to those of the feeding apparatuses of representatives of Mandibulata, apparently convergently evolved. Though the reconstruction of the evolution of the feeding apparatus within Euchelicerata is to a certain degree hampered by unclear phylogenetic relationships, there was clearly a shortening of the feeding apparatus from posterior (i.e. only the anterior appendages being involved in the feeding apparatus), probably linked to the colonisation of land in Arachnida.
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Affiliation(s)
- Carolin Haug
- Department of Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
- GeoBio-Center, Ludwig-Maximilians-Universität München, Munich, Germany
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25
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Budd GE, Mann RP. Survival and selection biases in early animal evolution and a source of systematic overestimation in molecular clocks. Interface Focus 2020; 10:20190110. [PMID: 32637066 PMCID: PMC7333906 DOI: 10.1098/rsfs.2019.0110] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/06/2020] [Indexed: 12/21/2022] Open
Abstract
Important evolutionary events such as the Cambrian Explosion have inspired many attempts at explanation: why do they happen when they do? What shapes them, and why do they eventually come to an end? However, much less attention has been paid to the idea of a 'null hypothesis'-that certain features of such diversifications arise simply through their statistical structure. Such statistical features also appear to influence our perception of the timing of these events. Here, we show in particular that study of unusually large clades leads to systematic overestimates of clade ages from some types of molecular clocks, and that the size of this effect may be enough to account for the puzzling mismatches seen between these molecular clocks and the fossil record. Our analysis of the fossil record of the late Ediacaran to Cambrian suggests that it is likely to be recording a true evolutionary radiation of the bilaterians at this time, and that explanations involving various sorts of cryptic origins for the bilaterians do not seem to be necessary.
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Affiliation(s)
- Graham E. Budd
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, Uppsala 752 36, Sweden
| | - Richard P. Mann
- Department of Statistics, School of Mathematics, University of Leeds, Leeds LS2 9JT, UK
- The Alan Turing Institute, London NW1 2DB, UK
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26
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Mángano MG, Buatois LA. The rise and early evolution of animals: where do we stand from a trace-fossil perspective? Interface Focus 2020; 10:20190103. [PMID: 32642049 DOI: 10.1098/rsfs.2019.0103] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2020] [Indexed: 01/10/2023] Open
Abstract
The trace-fossil record provides a wealth of information to track the rise and early evolution of animals. It comprises the activity of both hard- and soft-bodied organisms, is continuous through the Ediacaran (635-539 Ma)- Cambrian (539-485 Ma) transition, yields insights into animal behaviour and their role as ecosystem engineers, and allows for a more refined characterization of palaeoenvironmental context. In order to unravel macroevolutionary signals from the trace-fossil record, a variety of approaches is available, including not only estimation of degree of bioturbation, but also analysis of ichnodiversity and ichnodisparity trajectories, and evaluation of the occupation of infaunal ecospace and styles of ecosystem engineering. Analysis of the trace-fossil record demonstrates the presence of motile benthic bilaterians in the Ediacaran, mostly feeding from biofilms. Although Ediacaran trace fossils are simple and emplaced at or immediately below the sediment surface, an increase in ichnofossil complexity, predation pressure, sediment disturbance and penetration depth is apparent during the terminal Ediacaran. Regardless of this increase, a dramatic rise in trace fossil diversity and disparity took place during the earliest Cambrian, underscoring that the novelty of the Fortunian (539-529 Ma) cannot be underestimated. The Fortunian still shows the persistence of an Ediacaran-style matground ecology, but is fundamentally characterized by the appearance of new trace-fossil architectural plans reflecting novel ways of interacting with the substrate. The appearance of Phanerozoic-style benthic ecosystems attests to an increased length and connectivity of the food web and improved efficiency in organic carbon transfer and nutrient recycling. A profound reorganization of the infaunal ecospace is recorded in both high-energy sand-dominated nearshore areas and low-energy mud-dominated offshore environments, during the early Cambrian, starting approximately during Cambrian Age 2 (529-521 Ma), but continuing during the rest of the early Cambrian. A model comprising four evolutionary phases is proposed to synthetize information from the Ediacaran-Cambrian trace-fossil record. The use of a rich ichnological toolbox; critical, systematic and comprehensive evaluation of the Ediacaran-Cambrian trace-fossil record; and high-resolution integration of the ichnological dataset and sedimentological information show that the advent of biogenic mixing was an important factor in fully marine environments at the dawn of the Phanerozoic.
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Affiliation(s)
- M Gabriela Mángano
- Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan, Canada S7N 5E2
| | - Luis A Buatois
- Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan, Canada S7N 5E2
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27
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Pates S, Botting JP, McCobb LME, Muir LA. A miniature Ordovician hurdiid from Wales demonstrates the adaptability of Radiodonta. ROYAL SOCIETY OPEN SCIENCE 2020; 7:200459. [PMID: 32742697 PMCID: PMC7353989 DOI: 10.1098/rsos.200459] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 05/18/2020] [Indexed: 05/19/2023]
Abstract
Originally considered as large, solely Cambrian apex predators, Radiodonta-a clade of stem-group euarthropods including Anomalocaris-now comprises a diverse group of predators, sediment sifters and filter feeders. These animals are only known from deposits preserving non-biomineralized material, with radiodonts often the first and/or only taxa known from such deposits. Despite the widespread and diverse nature of the group, only a handful of radiodonts are known from post-Cambrian deposits, and all originate from deposits or localities rich in other total-group euarthropods. In this contribution, we describe the first radiodont from the UK, an isolated hurdiid frontal appendage from the Tremadocian (Lower Ordovician) Dol-cyn-Afon Formation, Wales, UK. This finding is unusual in two major aspects: firstly, the appendage (1.8 mm in size) is less than half the size of the next smallest radiodont frontal appendage known, and probably belonged to an animal between 6 and 15 mm in length; secondly, it was discovered in the sponge-dominated Afon Gam Biota, one of only a handful of non-biomineralized total-group euarthropods known from this deposit. This Welsh hurdiid breaks new ground for Radiodonta in terms of both its small size and sponge-dominated habitat. This occurrence demonstrates the adaptability of the group in response to the partitioning of ecosystems and environments in the late Cambrian and Early Ordovician world.
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Affiliation(s)
- Stephen Pates
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Oxford Street, Boston, MA 02138, USA
- Author for correspondence: Stephen Pates e-mail:
| | - Joseph P. Botting
- Department of Natural Sciences, Amgueddfa Cymru-National Museum Wales, Cathays Park, Cardiff CF10 3NP, UK
- Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing 210008, People's Republic of China
| | - Lucy M. E. McCobb
- Department of Natural Sciences, Amgueddfa Cymru-National Museum Wales, Cathays Park, Cardiff CF10 3NP, UK
| | - Lucy A. Muir
- Department of Natural Sciences, Amgueddfa Cymru-National Museum Wales, Cathays Park, Cardiff CF10 3NP, UK
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28
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Saleh F, Daley AC, Lefebvre B, Pittet B, Perrillat JP. Biogenic Iron Preserves Structures during Fossilization: A Hypothesis: Iron from Decaying Tissues May Stabilize Their Morphology in the Fossil Record. Bioessays 2020; 42:e1900243. [PMID: 32338399 DOI: 10.1002/bies.201900243] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 02/27/2020] [Indexed: 11/12/2022]
Abstract
It is hypothesized that iron from biological tissues, liberated during decay, may have played a role in inhibiting loss of anatomical information during fossilization of extinct organisms. Most tissues in the animal kingdom contain iron in different forms. A widely distributed iron-bearing molecule is ferritin, a globular protein that contains iron crystallites in the form of ferrihydrite minerals. Iron concentrations in ferritin are high and ferrihydrites are extremely reactive. When ancient animals are decaying on the sea floor under anoxic environmental conditions, ferrihydrites may initialize the selective replication of some tissues in pyrite FeS2 . This model explains why some labile tissues are preserved, while other more resistant structures decay and are absent in many fossils. A major implication of this hypothesis is that structures described as brains in Cambrian arthropods are not fossilization artifacts, but are instead a source of information on anatomical evolution at the dawn of complex animal life.
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Affiliation(s)
- Farid Saleh
- Université de Lyon, Université Claude Bernard Lyon1, École Normale Supérieure de Lyon, CNRS, UMR5276, LGL-TPE, Villeurbanne, 69622, France
| | - Allison C Daley
- Institute of Earth Sciences, University of Lausanne, Géopolis, Lausanne, CH-1015, Switzerland
| | - Bertrand Lefebvre
- Université de Lyon, Université Claude Bernard Lyon1, École Normale Supérieure de Lyon, CNRS, UMR5276, LGL-TPE, Villeurbanne, 69622, France
| | - Bernard Pittet
- Université de Lyon, Université Claude Bernard Lyon1, École Normale Supérieure de Lyon, CNRS, UMR5276, LGL-TPE, Villeurbanne, 69622, France
| | - Jean Philippe Perrillat
- Université de Lyon, Université Claude Bernard Lyon1, École Normale Supérieure de Lyon, CNRS, UMR5276, LGL-TPE, Villeurbanne, 69622, France
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29
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Hancy AD, Antcliffe JB. Anoxia can increase the rate of decay for cnidarian tissue: Using Actinia equina to understand the early fossil record. GEOBIOLOGY 2020; 18:167-184. [PMID: 31990129 DOI: 10.1111/gbi.12370] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 10/02/2019] [Accepted: 11/05/2019] [Indexed: 06/10/2023]
Abstract
An experimental decay methodology is developed for a cnidarian model organism to serve as a comparison to the many previous such studies on bilaterians. This allows an examination of inherent bias against the fossilisation of cnidarian tissue and their diagnostic characters, under what conditions these occur, and in what way. The decay sequence of Actinia equina was examined under a series of controlled conditions. These experiments show that cnidarian decay begins with an initial rupturing of the epidermis, followed by rapid loss of recognisable internal morphological characters. This suggests that bacteria work quicker on the epidermis than autolysis does on the internal anatomy. The data also show that diploblastic tissue is not universally decayed more slowly under anoxic or reducing conditions than under oxic conditions. Indeed, some cnidarian characters decay more rapidly under anoxic conditions than they do under oxic conditions. This suggests the decay pathways acting may be different to those affecting soft bilaterian tissue such as soft epidermis and internal organs. What is most important in the decay of soft polyp anatomy is the microbial community, which can be dominated by oxic or anoxic bacteria. Different Lagerstätte, even of the same type, will inevitably have subtle difference in their bacterial communities, which among other factors, could be a control on soft polyp preservation leading to either an absence of compelling soft anthozoans (Burgess Shale) or an astonishing abundance (Qingjiang biota).
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Affiliation(s)
- Anthony D Hancy
- School of Earth Sciences, University of Bristol, Bristol, UK
| | - Jonathan B Antcliffe
- Oxford University Museum of Natural History, Oxford, UK
- Institut des Sciences de la Terre, Bâtiment Géopolis, UNIL-Mouline, Université de Lausanne, Lausanne, Switzerland
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30
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Howard RJ, Hou X, Edgecombe GD, Salge T, Shi X, Ma X. A Tube-Dwelling Early Cambrian Lobopodian. Curr Biol 2020; 30:1529-1536.e2. [PMID: 32109391 DOI: 10.1016/j.cub.2020.01.075] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 12/09/2019] [Accepted: 01/24/2020] [Indexed: 01/27/2023]
Abstract
Facivermis yunnanicus [1, 2] is an enigmatic worm-like animal from the early Cambrian Chengjiang Biota of Yunnan Province, China. It is a small (<10 cm) bilaterian with five pairs of spiny anterior arms, an elongated body, and a swollen posterior end. The unusual morphology of Facivermis has prompted a history of diverse taxonomic interpretations, including among annelids [1, 3], lophophorates [4], and pentastomids [5]. However, in other studies, Facivermis is considered to be more similar to lobopodians [2, 6-8]-the fossil grade from which modern panarthropods (arthropods, onychophorans, and tardigrades) are derived. In these studies, Facivermis is thought to be intermediate between cycloneuralian worms and lobopodians. Facivermis has therefore been suggested to represent an early endobenthic-epibenthic panarthropod transition [6] and to provide crucial insights into the origin of paired appendages [2]. However, the systematic affinity of Facivermis was poorly supported in a previous phylogeny [6], partially due to incomplete understanding of its morphology. Therefore, the evolutionary significance of Facivermis remains unresolved. In this study, we re-examine Facivermis from new material and the holotype, leading to the discovery of several new morphological features, such as paired eyes on the head and a dwelling tube. Comprehensive phylogenetic analyses using parsimony, Bayesian inference, and maximum likelihood all support Facivermis as a luolishaniid in a derived position within the onychophoran stem group rather than as a basal panarthropod. In contrast to previous studies, we therefore conclude that Facivermis provides a rare early Cambrian example of secondary loss to accommodate a highly specialized tube-dwelling lifestyle.
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Affiliation(s)
- Richard J Howard
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Chenggong Campus, Kunming 650500, China; Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Cornwall TR10 9TA, UK; Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Xianguang Hou
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Chenggong Campus, Kunming 650500, China; Yunnan Key Laboratory for Palaeobiology, Yunnan University, Chenggong Campus, Kunming 650500, China.
| | - Gregory D Edgecombe
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Chenggong Campus, Kunming 650500, China; Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Tobias Salge
- Imaging and Analysis Centre, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Xiaomei Shi
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Chenggong Campus, Kunming 650500, China; Yunnan Key Laboratory for Palaeobiology, Yunnan University, Chenggong Campus, Kunming 650500, China
| | - Xiaoya Ma
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Chenggong Campus, Kunming 650500, China; Yunnan Key Laboratory for Palaeobiology, Yunnan University, Chenggong Campus, Kunming 650500, China; Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Cornwall TR10 9TA, UK.
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31
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Abstract
Ctenophores or 'comb-jellies' are marine animals whose relationship to other phyla is uncertain, yet important for understanding major steps in animal evolution. Fossil ctenophores from the Cambrian indicate that ctenophores may have evolved from a sessile, cnidarian-like ancestor.
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Affiliation(s)
- Allison C Daley
- Institute of Earth Sciences, University of Lausanne, Geopolis, CH-1015 Lausanne, Switzerland.
| | - Jonathan B Antcliffe
- Institute of Earth Sciences, University of Lausanne, Geopolis, CH-1015 Lausanne, Switzerland
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32
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Ortega-Hernández J, Lerosey-Aubril R, Pates S. Proclivity of nervous system preservation in Cambrian Burgess Shale-type deposits. Proc Biol Sci 2019; 286:20192370. [PMID: 31822253 PMCID: PMC6939931 DOI: 10.1098/rspb.2019.2370] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Recent investigations on neurological tissues preserved in Cambrian fossils have clarified the phylogenetic affinities and head segmentation in pivotal members of stem-group Euarthropoda. However, palaeoneuroanatomical features are often incomplete or described from single exceptional specimens, raising concerns about the morphological interpretation of fossilized neurological structures and their significance for early euarthropod evolution. Here, we describe the central nervous system (CNS) of the short great-appendage euarthropod Alalcomenaeus based on material from two Cambrian Burgess Shale-type deposits of the American Great Basin, the Pioche Formation (Stage 4) and the Marjum Formation (Drumian). The specimens reveal complementary ventral and lateral views of the CNS, preserved as a dark carbonaceous compression throughout the body. The head features a dorsal brain connected to four stalked ventral eyes, and four pairs of segmental nerves. The first to seventh trunk tergites overlie a ventral nerve cord with seven ganglia, each associated with paired sets of segmental nerve bundles. Posteriorly, the nerve cord features elongate thread-like connectives. The Great Basin fossils strengthen the original description—and broader evolutionary implications—of the CNS in Alalcomenaeus from the early Cambrian (Stage 3) Chengjiang deposit of South China. The spatio-temporal recurrence of fossilized neural tissues in Cambrian Konservat-Lagerstätten across North America (Pioche, Burgess Shale, Marjum) and South China (Chengjiang, Xiaoshiba) indicates that their preservation is consistent with the mechanism of Burgess Shale-type fossilization, without the need to invoke alternative taphonomic pathways or the presence of microbial biofilms.
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Affiliation(s)
- Javier Ortega-Hernández
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
| | - Rudy Lerosey-Aubril
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
| | - Stephen Pates
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
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33
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Chipman AD, Edgecombe GD. Developing an integrated understanding of the evolution of arthropod segmentation using fossils and evo-devo. Proc Biol Sci 2019; 286:20191881. [PMID: 31575373 DOI: 10.1098/rspb.2019.1881] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Segmentation is fundamental to the arthropod body plan. Understanding the evolutionary steps by which arthropods became segmented is being transformed by the integration of data from evolutionary developmental biology (evo-devo), Cambrian fossils that allow the stepwise acquisition of segmental characters to be traced in the arthropod stem-group, and the incorporation of fossils into an increasingly well-supported phylogenetic framework for extant arthropods based on genomic-scale datasets. Both evo-devo and palaeontology make novel predictions about the evolution of segmentation that serve as testable hypotheses for the other, complementary data source. Fossils underpin such hypotheses as arthropodization originating in a frontal appendage and then being co-opted into other segments, and segmentation of the endodermal midgut in the arthropod stem-group. Insights from development, such as tagmatization being associated with different modes of segment generation in different body regions, and a distinct patterning of the anterior head segments, are complemented by palaeontological evidence for the pattern of tagmatization during ontogeny of exceptionally preserved fossils. Fossil and developmental data together provide evidence for a short head in stem-group arthropods and the mechanism of its formation and retention. Future breakthroughs are expected from identification of molecular signatures of developmental innovations within a phylogenetic framework, and from a focus on later developmental stages to identify the differentiation of repeated units of different systems within segmental precursors.
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Affiliation(s)
- Ariel D Chipman
- Department of Ecology, Evolution and Behavior, The Silberman Institute of Life Sciences, Edmond J. Safra Campus - Givat Ram, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Gregory D Edgecombe
- Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
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34
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35
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Soft-bodied fossils from the upper Valongo Formation (Middle Ordovician: Dapingian-Darriwilian) of northern Portugal. Naturwissenschaften 2019; 106:27. [PMID: 31129730 DOI: 10.1007/s00114-019-1623-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 04/20/2019] [Accepted: 05/09/2019] [Indexed: 10/26/2022]
Abstract
Soft-bodied preservation is common in the Cambrian but comparatively rare in the Ordovician. Here, a new deposit preserving soft-bodied fossils is reported from the Middle Ordovician (Dapingian-Darriwilian) upper Valongo Formation of northern Portugal. The deposit contains the first known occurrences of soft-bodied fossils from the Middle Ordovician (Dapingian-Darriwilian) of Portugal and is the first Ordovician example of soft-tissue preservation involving carbonaceous films from the Iberian Peninsula. It also represents the lone deposit of soft-bodied fossils from the Middle Ordovician of northern Gondwana. Thus temporally, it lies between the exceptional deposits of the Lower Ordovician of Fezouata (Morocco) and the Upper Ordovician of the Soom Shale (South Africa); it also serves as a biogeographic link between these and the various Ordovician soft-bodied deposits in Laurentia. The soft-bodied fossils come from the deep-water slates of the upper part of the Valongo Formation and include a discoidal fossil questionably referable to Patanacta, wiwaxiid sclerites, and a possible pseudoarctolepid arthropod.
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36
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Sperling EA, Stockey RG. The Temporal and Environmental Context of Early Animal Evolution: Considering All the Ingredients of an "Explosion". Integr Comp Biol 2019; 58:605-622. [PMID: 30295813 DOI: 10.1093/icb/icy088] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Animals originated and evolved during a unique time in Earth history-the Neoproterozoic Era. This paper aims to discuss (1) when landmark events in early animal evolution occurred, and (2) the environmental context of these evolutionary milestones, and how such factors may have affected ecosystems and body plans. With respect to timing, molecular clock studies-utilizing a diversity of methodologies-agree that animal multicellularity had arisen by ∼800 million years ago (Ma) (Tonian period), the bilaterian body plan by ∼650 Ma (Cryogenian), and divergences between sister phyla occurred ∼560-540 Ma (late Ediacaran). Most purported Tonian and Cryogenian animal body fossils are unlikely to be correctly identified, but independent support for the presence of pre-Ediacaran animals is recorded by organic geochemical biomarkers produced by demosponges. This view of animal origins contrasts with data from the fossil record, and the taphonomic question of why animals were not preserved (if present) remains unresolved. Neoproterozoic environments demanding small, thin, body plans, and lower abundance/rarity in populations may have played a role. Considering environmental conditions, geochemical data suggest that animals evolved in a relatively low-oxygen ocean. Here, we present new analyses of sedimentary total organic carbon contents in shales suggesting that the Neoproterozoic ocean may also have had lower primary productivity-or at least lower quantities of organic carbon reaching the seafloor-compared with the Phanerozoic. Indeed, recent modeling efforts suggest that low primary productivity is an expected corollary of a low-O2 world. Combined with an inability to inhabit productive regions in a low-O2 ocean, earliest animal communities would likely have been more food limited than generally appreciated, impacting both ecosystem structure and organismal behavior. In light of this, we propose the "fire triangle" metaphor for environmental influences on early animal evolution. Moving toward consideration of all environmental aspects of the Cambrian radiation (fuel, heat, and oxidant) will ultimately lead to a more holistic view of the event.
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Affiliation(s)
- Erik A Sperling
- Department of Geological Sciences, Stanford University, 450 Serra Mall, Building 320, Stanford, CA 94305, USA
| | - Richard G Stockey
- Department of Geological Sciences, Stanford University, 450 Serra Mall, Building 320, Stanford, CA 94305, USA
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37
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Affiliation(s)
- Allison C Daley
- Institute of Earth Sciences, University of Lausanne, Geopolis, CH-1015 Lausanne, Switzerland.
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38
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Fu D, Tong G, Dai T, Liu W, Yang Y, Zhang Y, Cui L, Li L, Yun H, Wu Y, Sun A, Liu C, Pei W, Gaines RR, Zhang X. The Qingjiang biota-A Burgess Shale-type fossil Lagerstätte from the early Cambrian of South China. Science 2019; 363:1338-1342. [PMID: 30898931 DOI: 10.1126/science.aau8800] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Accepted: 02/05/2019] [Indexed: 12/21/2022]
Abstract
Burgess Shale-type fossil Lagerstätten provide the best evidence for deciphering the biotic patterns and magnitude of the Cambrian explosion. Here, we report a Lagerstätte from South China, the Qingjiang biota (~518 million years old), which is dominated by soft-bodied taxa from a distal shelf setting. The Qingjiang biota is distinguished by pristine carbonaceous preservation of labile organic features, a very high proportion of new taxa (~53%), and preliminary taxonomic diversity that suggests it could rival the Chengjiang and Burgess Shale biotas. Defining aspects of the Qingjiang biota include a high abundance of cnidarians, including both medusoid and polypoid forms; new taxa resembling extant kinorhynchs; and abundant larval or juvenile forms. This distinctive composition holds promise for providing insights into the evolution of Cambrian ecosystems across environmental gradients.
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Affiliation(s)
- Dongjing Fu
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi'an 710069, PR China
| | - Guanghui Tong
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi'an 710069, PR China
| | - Tao Dai
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi'an 710069, PR China
| | - Wei Liu
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi'an 710069, PR China
| | - Yuning Yang
- College of Resource and Environmental Engineering, Guizhou University, Guiyang 550025, PR China
| | - Yuan Zhang
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi'an 710069, PR China
| | - Linhao Cui
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi'an 710069, PR China
| | - Luoyang Li
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi'an 710069, PR China
| | - Hao Yun
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi'an 710069, PR China
| | - Yu Wu
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi'an 710069, PR China
| | - Ao Sun
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi'an 710069, PR China
| | - Cong Liu
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi'an 710069, PR China
| | - Wenrui Pei
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi'an 710069, PR China
| | - Robert R Gaines
- Department of Geology, Pomona College, Claremont, CA 91711, USA
| | - Xingliang Zhang
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environment, Department of Geology, Northwest University, Xi'an 710069, PR China.
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39
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Trilobite evolutionary rates constrain the duration of the Cambrian explosion. Proc Natl Acad Sci U S A 2019; 116:4394-4399. [PMID: 30782836 DOI: 10.1073/pnas.1819366116] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Trilobites are often considered exemplary for understanding the Cambrian explosion of animal life, due to their unsurpassed diversity and abundance. These biomineralized arthropods appear abruptly in the fossil record with an established diversity, phylogenetic disparity, and provincialism at the beginning of Cambrian Series 2 (∼521 Ma), suggesting a protracted but cryptic earlier history that possibly extends into the Precambrian. However, recent analyses indicate elevated rates of phenotypic and genomic evolution for arthropods during the early Cambrian, thereby shortening the phylogenetic fuse. Furthermore, comparatively little research has been devoted to understanding the duration of the Cambrian explosion, after which normal Phanerozoic evolutionary rates were established. We test these hypotheses by applying Bayesian tip-dating methods to a comprehensive dataset of Cambrian trilobites. We show that trilobites have a Cambrian origin, as supported by the trace fossil record and molecular clocks. Surprisingly, they exhibit constant evolutionary rates across the entire Cambrian, for all aspects of the preserved phenotype: discrete, meristic, and continuous morphological traits. Our data therefore provide robust, quantitative evidence that by the time the typical Cambrian fossil record begins (∼521 Ma), the Cambrian explosion had already largely concluded. This suggests that a modern-style marine biosphere had rapidly emerged during the latest Ediacaran and earliest Cambrian (∼20 million years), followed by broad-scale evolutionary stasis throughout the remainder of the Cambrian.
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40
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Gruen DS, Wolfe JM, Fournier GP. Paleozoic diversification of terrestrial chitin-degrading bacterial lineages. BMC Evol Biol 2019; 19:34. [PMID: 30691393 PMCID: PMC6348609 DOI: 10.1186/s12862-019-1357-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 01/09/2019] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Establishing the divergence times of groups of organisms is a major goal of evolutionary biology. This is especially challenging for microbial lineages due to the near-absence of preserved physical evidence (diagnostic body fossils or geochemical biomarkers). Horizontal gene transfer (HGT) can serve as a temporal scaffold between microbial groups and other fossil-calibrated clades, potentially improving these estimates. Specifically, HGT to or from organisms with fossil-calibrated age estimates can propagate these constraints to additional groups that lack fossils. While HGT is common between lineages, only a small subset of HGT events are potentially informative for dating microbial groups. RESULTS Constrained by published fossil-calibrated studies of fungal evolution, molecular clock analyses show that multiple clades of Bacteria likely acquired chitinase homologs via HGT during the very late Neoproterozoic into the early Paleozoic. These results also show that, following these HGT events, recipient terrestrial bacterial clades likely diversified ~ 300-500 million years ago, consistent with established timescales of arthropod and plant terrestrialization. CONCLUSIONS We conclude that these age estimates are broadly consistent with the dispersal of chitinase genes throughout the microbial world in direct response to the evolution and ecological expansion of detrital-chitin producing groups. The convergence of multiple lines of evidence demonstrates the utility of HGT-based dating methods in microbial evolution. The pattern of inheritance of chitinase genes in multiple terrestrial bacterial lineages via HGT processes suggests that these genes, and possibly other genes encoding substrate-specific enzymes, can serve as a "standard candle" for dating microbial lineages across the Tree of Life.
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Affiliation(s)
- Danielle S. Gruen
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543 USA
| | - Joanna M. Wolfe
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Gregory P. Fournier
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
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41
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Mángano MG, Hawkes CD, Caron JB. Trace fossils associated with Burgess Shale non-biomineralized carapaces: bringing taphonomic and ecological controls into focus. ROYAL SOCIETY OPEN SCIENCE 2019; 6:172074. [PMID: 30800334 PMCID: PMC6366168 DOI: 10.1098/rsos.172074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 12/17/2018] [Indexed: 06/09/2023]
Abstract
The association of trace fossils and non-biomineralized carapaces has been reported from Cambrian Lagerstätten worldwide, but the abundance, ichnodiversity, taphonomy and ecological significance of such associations have yet to be fully investigated. Two main end-member hypotheses are explored based on the study of a relatively wide variety of trace fossils preserved associated to Tuzoia carapaces from the middle Cambrian Burgess Shale in British Columbia. In the ecological Tuzoia garden hypothesis, the bacterially enriched surface of carapaces provides opportunities for intricate ecologic interactions among trophic levels. In the taphonomic shielding hypothesis, the trace fossil-carapace association results from preferential preservation of traces as controlled by compaction independent of any association in life. In an attempt to better understand the role of the carapace as a medium for preservation of trace fossils and to evaluate the effects of mechanical stress related to burial, a numerical model was developed. Results indicate that the carapace can shield underlying sediment from mechanical stress for a finite time, differentially protecting trace fossils during the initial phase of burial and compaction. However, this taphonomic model alone fails to fully explain relatively high-density assemblages displaying a diversity of structures spatially confined within the perimeter of carapaces or branching patterns recording re-visitation.
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Affiliation(s)
- M. Gabriela Mángano
- Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan S7N 5E2, Canada
| | - Christopher David Hawkes
- Department of Civil, Geological and Environmental Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Saskatchewan S7N 5A9, Canada
| | - Jean-Bernard Caron
- Department of Natural History-Palaeobiology, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario M5S 3B2, Canada
- Department of Earth Sciences, University of Toronto, Toronto, Ontario M5S 3B1, Canada
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42
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Abstract
The dynamics of how metazoan phyla appeared and evolved – known as the Cambrian Explosion – remains elusive. We present a quantitative analysis of the temporal distribution (based on occurrence data of fossil species sampled in each time interval) of lophotrochozoan skeletal species (n = 430) from the terminal Ediacaran to Cambrian Stage 5 (~545 – ~505 Million years ago (Ma)) of the Siberian Platform, Russia. We use morphological traits to distinguish between stem and crown groups. Possible skeletal stem group lophophorates, brachiopods, and molluscs (n = 354) appear in the terminal Ediacaran (~542 Ma) and diversify during the early Cambrian Terreneuvian and again in Stage 2, but were devastated during the early Cambrian Stage 4 Sinsk extinction event (~513 Ma) never to recover previous diversity. Inferred crown group brachiopod and mollusc species (n = 76) do not appear until the Fortunian, ~537 Ma, radiate in the early Cambrian Stage 3 (~522 Ma), and with minimal loss of diversity at the Sinsk Event, continued to diversify into the Ordovician. The Sinsk Event also removed other probable stem groups, such as archaeocyath sponges. Notably, this diversification starts before, and extends across the Ediacaran/Cambrian boundary and the Basal Cambrian Carbon Isotope Excursion (BACE) interval (~541 to ~540 Ma), ascribed to a possible global perturbation of the carbon cycle. We therefore propose two phases of the Cambrian Explosion separated by the Sinsk extinction event, the first dominated by stem groups of phyla from the late Ediacaran, ~542 Ma, to early Cambrian stage 4, ~513 Ma, and the second marked by radiating bilaterian crown group species of phyla from ~513 Ma and extending to the Ordovician Radiation.
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43
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Lerosey-Aubril R, Pates S. New suspension-feeding radiodont suggests evolution of microplanktivory in Cambrian macronekton. Nat Commun 2018; 9:3774. [PMID: 30218075 PMCID: PMC6138677 DOI: 10.1038/s41467-018-06229-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 08/09/2018] [Indexed: 11/23/2022] Open
Abstract
The rapid diversification of metazoans and their organisation in modern-style marine ecosystems during the Cambrian profoundly transformed the biosphere. What initially sparked this Cambrian explosion remains passionately debated, but the establishment of a coupling between pelagic and benthic realms, a key characteristic of modern-day oceans, might represent a primary ecological cause. By allowing the transfer of biomass and energy from the euphotic zone-the locus of primary production-to the sea floor, this biological pump would have boosted diversification within the emerging metazoan-dominated benthic communities. However, little is known about Cambrian pelagic organisms and their trophic interactions. Here we describe a filter-feeding Cambrian radiodont exhibiting morphological characters that likely enabled the capture of microplankton-sized particles, including large phytoplankton. This description of a large free-swimming suspension-feeder potentially engaged in primary consumption suggests a more direct involvement of nekton in the establishment of an oceanic pelagic-benthic coupling in the Cambrian.
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Affiliation(s)
- Rudy Lerosey-Aubril
- Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, Australia.
| | - Stephen Pates
- Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
- Institute of Earth Sciences, University of Lausanne, Lausanne, CH-1015, Switzerland
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