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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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2
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Zhang H, Xiao S, Eriksson ME, Duan B, Maas A. Musculature of an Early Cambrian cycloneuralian animal. Proc Biol Sci 2023; 290:20231803. [PMID: 37817588 PMCID: PMC10565385 DOI: 10.1098/rspb.2023.1803] [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: 08/10/2023] [Accepted: 09/18/2023] [Indexed: 10/12/2023] Open
Abstract
Cycloneuralians are ecdysozoans with a fossil record extending to the Early Cambrian Fortunian Age and represented mostly by cuticular integuments. However, internal anatomies of Fortunian cycloneuralians are virtually unknown, hampering our understanding of their functional morphology and phylogenetic relationships. Here we report the exceptional preservation of cycloneuralian introvert musculature in Fortunian rocks of South China. The musculature consists of an introvert body-wall muscular grid of four circular and 36 radially arranged longitudinal muscle bundles, as well as an introvert circular muscle associated with 19 roughly radially arranged, short retractors. Collectively, these features support at least a scalidophoran affinity, and the absence of muscles associated with a mouth cone and scalids further indicates a priapulan affinity. As in modern scalidophorans, the fossil musculature, and particularly the introvert circular muscle retractors, may have controlled introvert inversion and facilitated locomotion and feeding. This work supports the evolution of scalidophoran-like or priapulan-like introvert musculature in cycloneuralians at the beginning of the Cambrian Period.
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Affiliation(s)
- Huaqiao Zhang
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, People's Republic of China
| | - Shuhai Xiao
- Department of Geosciences, Virginia Tech, Blacksburg, VA 24061, USA
| | | | - Baichuan Duan
- Key Laboratory of Marine Geology and Metallogeny, First Institute of Oceanography, Ministry of Natural Resource, Qingdao 266061, People's Republic of China
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3
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Saleh F, Clements T, Perrier V, Daley AC, Antcliffe JB. Variations in preservation of exceptional fossils within concretions. SWISS JOURNAL OF PALAEONTOLOGY 2023; 142:20. [PMID: 37719137 PMCID: PMC10501951 DOI: 10.1186/s13358-023-00284-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 08/13/2023] [Indexed: 09/19/2023]
Abstract
Concretions are an interesting mode of preservation that can occasionally yield fossils with soft tissues. To properly interpret these fossils, an understanding of their fossilization is required. Probabilistic models are useful tools to identify variations between different Konservat-Lagerstätten that are separated spatially and temporally. However, the application of probabilistic modeling has been limited to Early Paleozoic Konservat-Lagerstätten preserved in shales. In this paper, the patterns of preservation of three concretionary Konservat-Lagerstätten-the Carboniferous Mazon Creek (USA) and Montceau-les-Mines (France), and the Silurian Herefordshire Lagerstätte (UK)-are analyzed using a statistical approach. It is demonstrated that the degree of biotic involvement, i.e., the degree to which a carcass dictates its own preservation, is connected to internal organ conditional probabilities-the probabilities of finding an internal organ associated with another structure such as biomineralized, sclerotized, cuticularized, or cellular body walls. In concretions that are externally forced with little biological mediation (e.g., Herefordshire), all internal organ conditional probabilities are uniform. As biological mediation in concretion formation becomes more pronounced, heterogeneities in conditional probabilities are introduced (e.g., Montceau-les-Mines and Mazon Creek). The three concretionary sites were also compared with previously investigated Konservat-Lagerstätten preserving fossils in shales to demonstrate how the developed probability framework aids in understanding the broad-scale functioning of preservation in Konservat-Lagerstätten. Supplementary Information The online version contains supplementary material available at 10.1186/s13358-023-00284-4.
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Affiliation(s)
- Farid Saleh
- Institute of Earth Sciences (ISTE), University of Lausanne, Geopolis, CH-1015 Lausanne, Switzerland
| | - Thomas Clements
- GeoZentrum Nordbayern, Friedrich-Alexander Universität Erlangen-Nürnberg, Loewenichstrasse 28, 91054 Erlangen, Germany
| | - Vincent Perrier
- Université de Lyon, UCBL, ENSL, CNRS, UMR 5276 LGL-TPE, 69622 Villeurbanne, France
| | - Allison C Daley
- Institute of Earth Sciences (ISTE), University of Lausanne, Geopolis, CH-1015 Lausanne, Switzerland
| | - Jonathan B Antcliffe
- Institute of Earth Sciences (ISTE), University of Lausanne, Geopolis, CH-1015 Lausanne, Switzerland
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Kimmig J, LaVine RJ, Schiffbauer JD, Egenhoff SO, Shelton KL, Leibach WW. Annelids from the Cambrian (Wuliuan Stage, Miaolingian) Spence Shale Lagerstätte of northern Utah, USA. HISTORICAL BIOLOGY 2023; 36:934-943. [PMID: 38800616 PMCID: PMC11114447 DOI: 10.1080/08912963.2023.2196685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 03/22/2023] [Indexed: 05/29/2024]
Abstract
The Spence Shale Member of the Langston Formation in northern Utah and southern Idaho preserves generally non-biomineralized fossil assemblages referred to as the Spence Shale Lagerstätte. The biota of this Lagerstätte is dominated by panarthropods, both biomineralized and soft-bodied examples, but also preserves diverse infaunal organisms, including species of scalidophorans, echinoderms, lobopodians, stalked filter feeders, and various problematic taxa. To date, however, only a single annelid fossil, originally assigned to Canadia sp., has been described from the Spence Shale. This lone specimen and another recently collected specimen were analyzed in this study using scanning electron microscopy and energy dispersive X-ray spectrometry. The previous occurrence is reassigned to Burgessochaeta cf. B. setigera Walcott, 1911. The new fossil, however, is identified as a novel polychaete taxon, Shaihuludia shurikeni gen. et sp. nov., characterized by the presence of fused, bladed chaetae and a wide body. The occurrence of Burgessochaeta is the first outside the Burgess Shale and its vicinity, whereas Shaihuludia shurikeni gen. et sp. nov. adds to the diversity of annelids in the middle Cambrian and highlights the diversity of the Spence Shale Lagerstätte.
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Affiliation(s)
- Julien Kimmig
- Abteilung Geowissenschaften, Staatliches Museum für Naturkunde Karlsruhe, Karlsruhe, 76133, Germany
- The Harold Hamm School of Geology & Geological Engineering, University of North Dakota, Grand Forks, ND 58202, USA
| | - Rhiannon J. LaVine
- Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA
| | - James D. Schiffbauer
- Department of Geological Sciences, University of Missouri, Columbia, MO 65211, USA
- X-ray Microanalysis Laboratory, University of Missouri, Columbia, MO 65211, USA
| | - Sven O. Egenhoff
- The Harold Hamm School of Geology & Geological Engineering, University of North Dakota, Grand Forks, ND 58202, USA
| | - Kevin L. Shelton
- Department of Geological Sciences, University of Missouri, Columbia, MO 65211, USA
| | - Wade W. Leibach
- Department of Geological Sciences, University of Missouri, Columbia, MO 65211, USA
- Jacobs Solutions, St. Louis, MO 63102, USA
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Dong XP, Duan B, Liu J, Donoghue PCJ. Internal anatomy of a fossilized embryonic stage of the Cambrian-Ordovician scalidophoran Markuelia. ROYAL SOCIETY OPEN SCIENCE 2022; 9:220115. [PMID: 36249341 PMCID: PMC9532980 DOI: 10.1098/rsos.220115] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 09/14/2022] [Indexed: 06/16/2023]
Abstract
The Wangcun fossil Lagerstätte in Hunan, South China, has yielded hundreds of fossilized embryos of Markuelia hunanensis representing different developmental stages. Internal tissues have only rarely been observed, impeding further understanding of the soft tissue anatomy, phylogenetic affinity and evolutionary significance of Markuelia. In this study, we used synchrotron radiation X-ray tomographic microscopy (SRXTM) to study a new collection of fossil embryos from the Wangcun fossil Lagerstätte. We describe specimens exhibiting a spectrum of preservation states, the best of which preserves palisade structures underneath the cuticle of the head and tail, distinct from patterns of centripetal mineralization of the cuticle and centrifugal mineralization of hypha-like structures, seen elsewhere in this specimen and other fossils within the same assemblage. Our computed tomographic reconstruction of these mineralization phases preserves the gross morphology of (i) longitudinal structures associated with the tail spines, which we interpret as the proximal ends of longitudinal muscles, and (ii) a ring-shaped structure internal to the introvert, which we interpret as a ring-shaped brain, as anticipated of the cycloneuralian affinity of Markuelia. This is the first record of a fossilized nervous system in a scalidophoran, and the first instance in Orsten-style preservation, opening the potential for further such records within this widespread mode of high-fidelity three-dimensional preservation.
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Affiliation(s)
- Xi-ping Dong
- School of Earth and Space Science, Peking University, Beijing 100871, People's Republic of China
| | - Baichuan Duan
- Key Laboratory of Marine Geology and Metallogeny, First Institute of Oceanography, Ministry of Natural Resource, Qingdao 266061, People's Republic of China
| | - Jianbo Liu
- School of Earth and Space Science, Peking University, Beijing 100871, People's Republic of China
| | - Philip C. J. Donoghue
- Bristol Palaeobiology Group, School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK
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6
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Janssen K, Mähler B, Rust J, Bierbaum G, McCoy VE. The complex role of microbial metabolic activity in fossilization. Biol Rev Camb Philos Soc 2021; 97:449-465. [PMID: 34649299 DOI: 10.1111/brv.12806] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 09/30/2021] [Accepted: 10/05/2021] [Indexed: 12/22/2022]
Abstract
Bacteria play an important role in the fossilization of soft tissues; their metabolic activities drive the destruction of the tissues and also strongly influence mineralization. Some environmental conditions, such as anoxia, cold temperatures, and high salinity, are considered widely to promote fossilization by modulating bacterial activity. However, bacteria are extremely diverse, and have developed metabolic adaptations to a wide range of stressful conditions. Therefore, the influence of the environment on bacterial activity, and of their metabolic activity on fossilization, is complex. A number of examples illustrate that simple, general assumptions about the role of bacteria in soft tissue fossilization cannot explain all preservational pathways: (i) experimental results show that soft tissues of cnidaria decay less in oxic than anoxic conditions, and in the fossil record are found more commonly in fossil sites deposited under oxic conditions rather than anoxic environments; (ii) siderite concretions, which often entomb soft tissue fossils, precipitate due to a complex mixture of sulfate- and iron reduction by some bacterial species, running counter to original theories that iron reduction is the primary driver of siderite concretion growth; (iii) arthropod brains, now widely accepted to be preserved in many Cambrian fossil sites, are one of the first structures to decay in taphonomic experiments, indicating that their fossilization processes are complex and influenced by bacterial activity. In order to expand our understanding of the complex process of bacterially driven soft tissue fossilization, more research needs to be done, on fossils themselves and in taphonomic experiments, to determine how the complex variation in microbial metabolic activity influences decay and mineralization.
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Affiliation(s)
- Kathrin Janssen
- Institute of Medical Microbiology, Immunology and Parasitology, Medical Faculty, Rheinische Friedrich-Wilhelms Universität, 53127, Bonn, Germany
| | - Bastian Mähler
- Paleontology Section, Institute of Geosciences, Rheinische Friedrich-Wilhelms Universität Bonn, 53115, Bonn, Germany
| | - Jes Rust
- Paleontology Section, Institute of Geosciences, Rheinische Friedrich-Wilhelms Universität Bonn, 53115, Bonn, Germany
| | - Gabriele Bierbaum
- Institute of Medical Microbiology, Immunology and Parasitology, Medical Faculty, Rheinische Friedrich-Wilhelms Universität, 53127, Bonn, Germany
| | - Victoria E McCoy
- Department of Geosciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, 53211, U.S.A
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7
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Parry LA, Lerosey-Aubril R, Weaver JC, Ortega-Hernández J. Cambrian comb jellies from Utah illuminate the early evolution of nervous and sensory systems in ctenophores. iScience 2021; 24:102943. [PMID: 34522849 PMCID: PMC8426560 DOI: 10.1016/j.isci.2021.102943] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 06/01/2021] [Accepted: 07/30/2021] [Indexed: 12/11/2022] Open
Abstract
Ctenophores are a group of predatory macroinvertebrates whose controversial phylogenetic position has prompted several competing hypotheses regarding the evolution of animal organ systems. Although ctenophores date back at least to the Cambrian, they have a poor fossil record due to their gelatinous bodies. Here, we describe two ctenophore species from the Cambrian of Utah, which illuminate the early evolution of nervous and sensory features in the phylum. Thalassostaphylos elegans has 16 comb rows, an oral skirt, and an apical organ with polar fields. Ctenorhabdotus campanelliformis has 24 comb rows, an oral skirt, an apical organ enclosed by a capsule and neurological tissues preserved as carbonaceous films. These are concentrated around the apical organ and ciliated furrows, which connect to a circumoral nerve ring via longitudinal axons. C. campanelliformis deviates from the neuroanatomy of living ctenophores and demonstrates a substantial complexity in the nervous system of Cambrian ctenophores. Two species of rare fossil ctenophores are described from the Cambrian of Utah Fossil ctenophores preserve remains of nervous tissue and sensory structures Neurological structures include an oral nerve ring and giant longitudinal axons Cambrian ctenophores had a more complex neuroanatomy than living species
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Affiliation(s)
- Luke A Parry
- Department of Earth Sciences, University of Oxford, 3 South Parks Road, Oxford, OX1 3AN, UK.,Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA
| | - Rudy Lerosey-Aubril
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA
| | - James C Weaver
- Wyss Institute for Biologically Inspired Engineering, Harvard University, 60 Oxford Street, Cambridge, MA 02138, USA
| | - 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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8
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Asher RJ, Smith MR. Phylogenetic Signal and Bias in Paleontology. Syst Biol 2021; 71:986-1008. [PMID: 34469583 PMCID: PMC9248965 DOI: 10.1093/sysbio/syab072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 08/24/2021] [Accepted: 08/27/2021] [Indexed: 11/12/2022] Open
Abstract
An unprecedented amount of evidence now illuminates the phylogeny of living mammals and birds on the Tree of Life. We use this tree to measure phylogenetic value of data typically used in paleontology (bones and teeth) from six datasets derived from five published studies. We ask three interrelated questions: 1) Can these data adequately reconstruct known parts of the Tree of Life? 2) Is accuracy generally similar for studies using morphology, or do some morphological datasets perform better than others? 3) Does the loss of non-fossilizable data cause taxa to occur in misleadingly basal positions? Adding morphology to DNA datasets usually increases congruence of resulting topologies to the well corroborated tree, but this varies among morphological datasets. Extant taxa with a high proportion of missing morphological characters can greatly reduce phylogenetic resolution when analyzed together with fossils. Attempts to ameliorate this by deleting extant taxa missing morphology are prone to decreased accuracy due to long-branch artefacts. We find no evidence that fossilization causes extinct taxa to incorrectly appear at or near topologically basal branches. Morphology comprises the evidence held in common by living taxa and fossils, and phylogenetic analysis of fossils greatly benefits from inclusion of molecular and morphological data sampled for living taxa, whatever methods are used for phylogeny estimation.
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Affiliation(s)
- Robert J Asher
- Department of Zoology, Downing St., University of Cambridge CB2 3EJ, UK
| | - Martin R Smith
- Department of Earth Sciences, Lower Mount Joy, Durham University, Durham DH1 3LE, UK
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9
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Howard RJ, Edgecombe GD, Shi X, Hou X, Ma X. Ancestral morphology of Ecdysozoa constrained by an early Cambrian stem group ecdysozoan. BMC Evol Biol 2020; 20:156. [PMID: 33228518 PMCID: PMC7684930 DOI: 10.1186/s12862-020-01720-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 11/08/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ecdysozoa are the moulting protostomes, including arthropods, tardigrades, and nematodes. Both the molecular and fossil records indicate that Ecdysozoa is an ancient group originating in the terminal Proterozoic, and exceptional fossil biotas show their dominance and diversity at the beginning of the Phanerozoic. However, the nature of the ecdysozoan common ancestor has been difficult to ascertain due to the extreme morphological diversity of extant Ecdysozoa, and the lack of early diverging taxa in ancient fossil biotas. RESULTS Here we re-describe Acosmia maotiania from the early Cambrian Chengjiang Biota of Yunnan Province, China and assign it to stem group Ecdysozoa. Acosmia features a two-part body, with an anterior proboscis bearing a terminal mouth and muscular pharynx, and a posterior annulated trunk with a through gut. Morphological phylogenetic analyses of the protostomes using parsimony, maximum likelihood and Bayesian inference, with coding informed by published experimental decay studies, each placed Acosmia as sister taxon to Cycloneuralia + Panarthropoda-i.e. stem group Ecdysozoa. Ancestral state probabilities were calculated for key ecdysozoan nodes, in order to test characters inferred from fossils to be ancestral for Ecdysozoa. Results support an ancestor of crown group ecdysozoans sharing an annulated vermiform body with a terminal mouth like Acosmia, but also possessing the pharyngeal armature and circumoral structures characteristic of Cambrian cycloneuralians and lobopodians. CONCLUSIONS Acosmia is the first taxon placed in the ecdysozoan stem group and provides a constraint to test hypotheses on the early evolution of Ecdysozoa. Our study suggests acquisition of pharyngeal armature, and therefore a change in feeding strategy (e.g. predation), may have characterised the origin and radiation of crown group ecdysozoans from Acosmia-like ancestors.
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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
| | - 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
| | - Xiaomei Shi
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Chenggong Campus, Kunming, 650500, China
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Chenggong Campus, Kunming, 650500, China
| | - Xianguang Hou
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Chenggong Campus, Kunming, 650500, China.
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, 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, Institute of Palaeontology, 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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10
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Anderson RP. Intrinsic Iron May Have Promoted Ancient Nervous Tissue Fossilization. Bioessays 2020; 42:e2000070. [PMID: 32363611 DOI: 10.1002/bies.202000070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Indexed: 11/11/2022]
Affiliation(s)
- Ross P Anderson
- All Souls College, University of Oxford, Oxford, OX1 4AL, UK.,Department of Earth Sciences, University of Oxford, Oxford, OX1 3AN, UK
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11
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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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12
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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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13
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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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Fonseca ESS, Hiromori Y, Kaite Y, Ruivo R, Franco JN, Nakanishi T, Santos MM, Castro LFC. An Orthologue of the Retinoic Acid Receptor (RAR) Is Present in the Ecdysozoa Phylum Priapulida. Genes (Basel) 2019; 10:genes10120985. [PMID: 31795452 PMCID: PMC6947571 DOI: 10.3390/genes10120985] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 11/26/2019] [Accepted: 11/27/2019] [Indexed: 12/19/2022] Open
Abstract
Signalling molecules and their cognate receptors are central components of the Metazoa endocrine system. Defining their presence or absence in extant animal lineages is critical to accurately devise evolutionary patterns, physiological shifts and the impact of endocrine disrupting chemicals. Here, we address the evolution of retinoic acid (RA) signalling in the Priapulida worm, Priapulus caudatus Lamarck, 1816, an Ecdysozoa. RA signalling has been shown to be central to chordate endocrine homeostasis, participating in multiple developmental and physiological processes. Priapulids, with their slow rate of molecular evolution and phylogenetic position, represent a key taxon to investigate the early phases of Ecdysozoa evolution. By exploring a draft genome assembly, we show, by means of phylogenetics and functional assays, that an orthologue of the nuclear receptor retinoic acid receptor (RAR) subfamily, a central mediator of RA signalling, is present in Ecdysozoa, contrary to previous perception. We further demonstrate that the Priapulida RAR displays low-affinity for retinoids (similar to annelids), and is not responsive to common endocrine disruptors acting via RAR. Our findings provide a timeline for RA signalling evolution in the Bilateria and give support to the hypothesis that the increase in RA affinity towards RAR is a late acquisition in the evolution of the Metazoa.
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Affiliation(s)
- Elza S. S. Fonseca
- CIIMAR/CIMAR Interdisciplinary Centre of Marine and Environmental Research, U.Porto, 4450-208 Matosinhos, Portugal; (E.S.S.F.); (R.R.); (J.N.F.)
- FCUP—Faculty of Sciences, Department of Biology, U.Porto, 4169-007 Porto, Portugal
| | - Youhei Hiromori
- Laboratory of Hygienic Chemistry and Molecular Toxicology, Gifu Pharmaceutical University, Gifu 501-1196, Japan; (Y.H.); (Y.K.)
- Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Suzuka 513-8670, Japan
| | - Yoshifumi Kaite
- Laboratory of Hygienic Chemistry and Molecular Toxicology, Gifu Pharmaceutical University, Gifu 501-1196, Japan; (Y.H.); (Y.K.)
| | - Raquel Ruivo
- CIIMAR/CIMAR Interdisciplinary Centre of Marine and Environmental Research, U.Porto, 4450-208 Matosinhos, Portugal; (E.S.S.F.); (R.R.); (J.N.F.)
| | - João N. Franco
- CIIMAR/CIMAR Interdisciplinary Centre of Marine and Environmental Research, U.Porto, 4450-208 Matosinhos, Portugal; (E.S.S.F.); (R.R.); (J.N.F.)
| | - Tsuyoshi Nakanishi
- Laboratory of Hygienic Chemistry and Molecular Toxicology, Gifu Pharmaceutical University, Gifu 501-1196, Japan; (Y.H.); (Y.K.)
- Correspondence: (T.N.); (M.M.S.); (L.F.C.C.)
| | - Miguel M. Santos
- CIIMAR/CIMAR Interdisciplinary Centre of Marine and Environmental Research, U.Porto, 4450-208 Matosinhos, Portugal; (E.S.S.F.); (R.R.); (J.N.F.)
- FCUP—Faculty of Sciences, Department of Biology, U.Porto, 4169-007 Porto, Portugal
- Correspondence: (T.N.); (M.M.S.); (L.F.C.C.)
| | - L. Filipe C. Castro
- CIIMAR/CIMAR Interdisciplinary Centre of Marine and Environmental Research, U.Porto, 4450-208 Matosinhos, Portugal; (E.S.S.F.); (R.R.); (J.N.F.)
- FCUP—Faculty of Sciences, Department of Biology, U.Porto, 4169-007 Porto, Portugal
- Correspondence: (T.N.); (M.M.S.); (L.F.C.C.)
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15
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Parry L, Caron JB. Canadia spinosa and the early evolution of the annelid nervous system. SCIENCE ADVANCES 2019; 5:eaax5858. [PMID: 31535028 PMCID: PMC6739095 DOI: 10.1126/sciadv.aax5858] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 08/09/2019] [Indexed: 05/19/2023]
Abstract
Annelid worms are a disparate, primitively segmented clade of bilaterians that first appear during the early Cambrian Period. Reconstructing their early evolution is complicated by the extreme morphological diversity in early diverging lineages, rapid diversification, and sparse fossil record. Canadia spinosa, a Burgess Shale fossil polychaete, is redescribed as having palps with feeding grooves, a dorsal median antenna and biramous parapodia associated with the head and flanking a ventral mouth. Carbonaceously preserved features are identified as a terminal brain, circumoral connectives, a midventral ganglionated nerve cord and prominent parapodial nerves. Phylogenetic analysis recovers neuroanatomically simple extant taxa as the sister group of other annelids, but the phylogenetic position of Canadia suggests that the annelid ancestor was reasonably complex neuroanatomically and that reduction of the nervous system occurred several times independently in the subsequent 500 million years of annelid evolution.
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Affiliation(s)
- Luke Parry
- Department of Natural History, Palaeobiology, Royal Ontario Museum, 100 Queen’s Park, Toronto, Ontario M5S 2C6, Canada
- Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA
- Corresponding author.
| | - Jean-Bernard Caron
- Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario M5S 3B2, Canada
- Department of Earth Sciences, University of Toronto, Toronto, Ontario M5S 3B1, Canada
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16
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Wang D, Vannier J, Schumann I, Wang X, Yang XG, Komiya T, Uesugi K, Sun J, Han J. Origin of ecdysis: fossil evidence from 535-million-year-old scalidophoran worms. Proc Biol Sci 2019; 286:20190791. [PMID: 31288707 DOI: 10.1098/rspb.2019.0791] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
With millions of extant species, ecdysozoans (Scalidophora, Nematoida and Panarthropoda) constitute a major portion of present-day biodiversity. All ecdysozoans secrete an exoskeletal cuticle which must be moulted periodically and replaced by a larger one. Although moulting (ecdysis) has been recognized in early Palaeozoic panarthropods such as trilobites and basal groups such as anomalocaridids and lobopodians, the fossil record lacks clear evidence of ecdysis in early scalidophorans, largely because of difficulties in recognizing true exuviae. Here, we describe two types of exuviae in microscopic scalidophoran worms from the lowermost Cambrian Kuanchuanpu Formation ( ca 535 Ma) of China and reconstruct their moulting process. These basal scalidophorans moulted in a manner similar to that of extant priapulid worms, extricating themselves smoothly from their old tubular cuticle or turning their exuviae inside out like the finger of a glove. This is the oldest record of moulting in ecdysozoans. We also discuss the origin of ecdysis in the light of recent molecular analyses and the significance of moulting in the early evolution of animals.
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Affiliation(s)
- Deng Wang
- 1 State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University , Xi'an 710069 , People's Republic of China.,2 Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement (CNRS-UMR 5276), Université Claude Bernard Lyon 1 , Villeurbanne Cedex 69622 , France
| | - Jean Vannier
- 2 Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement (CNRS-UMR 5276), Université Claude Bernard Lyon 1 , Villeurbanne Cedex 69622 , France
| | - Isabell Schumann
- 3 Department of Genetics, University of Leipzig , Talstraße 33, 04103 Leipzig , Germany.,4 Molecular Evolution & Animal Systematics, Institute of Biology, University of Leipzig , Talstraße 33, 04103 Leipzig , Germany
| | - Xing Wang
- 5 Qingdao Institute of Marine Geology, China Geological Survey , Qingdao 266071 , People's Republic of China
| | - Xiao-Guang Yang
- 1 State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University , Xi'an 710069 , People's Republic of China
| | - Tsuyoshi Komiya
- 6 Department of Earth Science and Astronomy, Graduate School of Arts and Sciences, University of Tokyo , Tokyo 153-8902 , Japan
| | - Kentaro Uesugi
- 7 Japan Synchrotron Radiation Research Institute (JASRI) , 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo , Japan
| | - Jie Sun
- 1 State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University , Xi'an 710069 , People's Republic of China
| | - Jian Han
- 1 State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University , Xi'an 710069 , People's Republic of China
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17
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Liu J, Steiner M, Dunlop JA, Shu D. Microbial decay analysis challenges interpretation of putative organ systems in Cambrian fuxianhuiids. Proc Biol Sci 2019; 285:rspb.2018.0051. [PMID: 29643211 DOI: 10.1098/rspb.2018.0051] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 03/15/2018] [Indexed: 11/12/2022] Open
Abstract
The Chengjiang fossil Lagerstätte (Cambrian Stage 3) from Yunnan, southern China is renowned for its soft-tissue preservation. Accordingly structures in fuxianhuiids, radiodontans and great appendage arthropods have been interpreted as the nervous and cardiovascular systems, including brains, hearts and blood vessels. That such delicate organ systems survive the fossilization process seems remarkable; given that this mode of preservation involves major taphonomic changes, such as flattening, microbial degradation, chemical alteration and replacement. Here, we document a range of taphonomic preservation states in numerous articulated individuals of Fuxianhuia protensa We suggest that organic (partly iron mineral-replaced) bulbous structures in the head region, previously interpreted as brain tissue, along with sagittally located organic strands interpreted as part of the cardiovascular system or as nerve cords, may be better explained as microbial biofilms that developed following decomposition of the intestine, muscle and other connective tissues, forming halos surrounding the original organic remains.
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Affiliation(s)
- Jianni Liu
- Early Life Institute, Shaanxi Key Laboratory of Early Life and Environments, The Key Laboratory of Continental Dynamics, Northwest University, Xi'an 710069, People's Republic of China
| | - Michael Steiner
- Department of Earth Science, Freie Universität Berlin, 12249, Berlin, Germany
| | - Jason A Dunlop
- Museum für Naturkunde, Leibniz Institute for Research on Evolution and Biodiversity at the Humboldt University Berlin, 10115 Berlin, Germany
| | - Degan Shu
- Early Life Institute, Shaanxi Key Laboratory of Early Life and Environments, The Key Laboratory of Continental Dynamics, Northwest University, Xi'an 710069, People's Republic of China.,School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, People's Republic of China
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18
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Abstract
The sequence of decay in fern pinnules was tracked using the species Davallia canariensis. Taphonomic alterations in the sediment–water interface (control tanks) and in subaqueous conditions with microbial mats were compared. The decay sequences were similar in control and mat tanks; in both cases, pinnules preserved the shape throughout the four-month experience. However, the quality and integrity of tissues were greater in mats. In control tanks, in which we detected anoxic and neutral acid conditions, the appearance of a fungal–bacterial biofilm promoted mechanical (cell breakage and tissue distortions) and geochemical changes (infrequent mineralizations) on the external and internal pinnule tissues. In mats, characterized by stable dissolved oxygen and basic pH, pinnules became progressively entombed. These settings, together with the products derived from mat metabolisms (exopolymeric substances, proteins, and rich-Ca nucleation), promoted the integrity of external and internal tissues, and favored massive and diverse mineralization processes. The experience validates that the patterns of taphonomic alterations may be applied in fossil plants.
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19
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Abstract
Recent discoveries of fossil nervous tissue in Cambrian fossils have allowed researchers to trace the origin and evolution of the complex arthropod head and brain based on stem groups close to the origin of the clade, rather than on extant, highly derived members. Here we show that Kerygmachela from Sirius Passet, North Greenland, a primitive stem-group euarthropod, exhibits a diminutive (protocerebral) brain that innervates both the eyes and frontal appendages. It has been surmised, based on developmental evidence, that the ancestor of vertebrates and arthropods had a tripartite brain, which is refuted by the fossil evidence presented here. Furthermore, based on the discovery of eyes in Kerygmachela, we suggest that the complex compound eyes in arthropods evolved from simple ocelli, present in onychophorans and tardigrades, rather than through the incorporation of a set of modified limbs. The arthropod head is complex and its evolution has been difficult to reconstruct. Here, Park et al. describe new specimens of the Cambrian stem-group euarthropod Kerygmachela that preserve evidence of primitive compound eyes and a unipartite brain, providing insight into the structure of the early arthropod head.
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20
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Esteve J, Zhao YL, Maté-González MÁ, Gómez-Heras M, Peng J. A new high-resolution 3-D quantitative method for analysing small morphological features: an example using a Cambrian trilobite. Sci Rep 2018; 8:2868. [PMID: 29434204 PMCID: PMC5809599 DOI: 10.1038/s41598-018-21088-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 01/26/2018] [Indexed: 11/09/2022] Open
Abstract
Taphonomic processes play an important role in the preservation of small morphological features such as granulation or pits. However, the assessment of these features may face the issue of the small size of the specimens and, sometimes, the destructiveness of these analyses, which makes impossible carrying them out in singular specimen, such as holotypes or lectotypes. This paper takes a new approach to analysing small-morphological features, by using an optical surface roughness (OSR) meter to create a high-resolution three-dimensional digital-elevation model (DEM). This non-destructive technique allows analysing quantitatively the DEM using geometric morphometric methods (GMM). We created a number of DEMs from three populations putatively belonging to the same species of trilobite (Oryctocephalus indicus) that present the same cranidial outline, but differ in the presence or absence of the second and third transglabellar furrows. Profile analysis of the DEMs demonstrate that all three populations show similar preservation variation in the glabellar furrows and lobes. The GMM shows that all populations exhibit the same range of variation. Differences in preservation are a consequence of different degrees of cementation and rates of dissolution. Fast cementation enhances the preservation of glabellar furrows and lobes, while fast dissolution hampers preservation of the same structures.
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Affiliation(s)
- Jorge Esteve
- Departamento de Geociencias, Universidad de los Andes, Cra 1 No 18A-10, AA 4976, Bogotá D.C, Colombia.
| | - Yuan-Long Zhao
- Resources and Environmental Engineering College, Guizhou University, Guiyang, 550025, China
| | - Miguel Ángel Maté-González
- Department of Cartography and Terrain Engineering, Polytechnic School of Ávila, University of Salamanca, 05003, Ávila, Spain.,C.A.I. Arqueometry and Archaeological Analysis, Complutense University of Madrid, 28040, Madrid, Spain
| | - Miguel Gómez-Heras
- Departamento de Geología y Geoquímica Universidad Autónoma de Madrid, 28049, Madrid, Spain.,Instituto de Geociencias (CSIC, UCM), 28040, Madrid, Spain
| | - Jin Peng
- Resources and Environmental Engineering College, Guizhou University, Guiyang, 550025, China
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21
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Sansom RS, Wills MA. Differences between hard and soft phylogenetic data. Proc Biol Sci 2017; 284:20172150. [PMID: 29237859 PMCID: PMC5745416 DOI: 10.1098/rspb.2017.2150] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 11/15/2017] [Indexed: 11/20/2022] Open
Abstract
When building the tree of life, variability of phylogenetic signal is often accounted for by partitioning gene sequences and testing for differences. The same considerations, however, are rarely applied to morphological data, potentially undermining its use in evolutionary contexts. Here, we apply partition heterogeneity tests to 59 animal datasets to demonstrate that significant differences exist between the phylogenetic signal conveyed by 'hard' and 'soft' characters (bones, teeth and shells versus myology, integument etc). Furthermore, the morphological partitions differ significantly in their consistency relative to independent molecular trees. The observed morphological differences correspond with missing data biases, and as such their existence presents a problem not only for phylogeny reconstruction, but also for interpretations of fossil data. Evolutionary inferences drawn from clades in which hard, readily fossilizable characters are relatively less consistent and different from other morphology (mammals, bivalves) may be less secure. More secure inferences might be drawn from the fossil record of clades that exhibit fewer differences, or exhibit more consistent hard characters (fishes, birds). In all cases, it will be necessary to consider the impact of missing data on empirical data, and the differences that exist between morphological modules.
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Affiliation(s)
- Robert S Sansom
- School of Earth and Environmental Sciences, University of Manchester, Manchester M13 9PT, UK
| | - Matthew A Wills
- Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
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22
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Parry LA, Smithwick F, Nordén KK, Saitta ET, Lozano-Fernandez J, Tanner AR, Caron JB, Edgecombe GD, Briggs DEG, Vinther J. Soft-Bodied Fossils Are Not Simply Rotten Carcasses - Toward a Holistic Understanding of Exceptional Fossil Preservation. Bioessays 2017; 40. [DOI: 10.1002/bies.201700167] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 10/21/2017] [Indexed: 12/31/2022]
Affiliation(s)
- Luke A. Parry
- School of Earth Sciences, University of Bristol, Wills Memorial Building; Queen's Road Bristol BS8 1RJ UK
- Royal Ontario Museum; 100 Queen's Park Toronto ON M5S 2C6 Canada
- Department of Earth Sciences, The Natural History Museum; Cromwell Road London SW7 5BD UK
| | - Fiann Smithwick
- Royal Ontario Museum; 100 Queen's Park Toronto ON M5S 2C6 Canada
| | - Klara K. Nordén
- Royal Ontario Museum; 100 Queen's Park Toronto ON M5S 2C6 Canada
| | - Evan T. Saitta
- Royal Ontario Museum; 100 Queen's Park Toronto ON M5S 2C6 Canada
| | - Jesus Lozano-Fernandez
- School of Biological Sciences, University of Bristol; Life Sciences Building, 24 Tyndall Avenue Bristol BS8 1TQ UK
| | - Alastair R. Tanner
- School of Biological Sciences, University of Bristol; Life Sciences Building, 24 Tyndall Avenue Bristol BS8 1TQ UK
| | - Jean-Bernard Caron
- School of Earth Sciences, University of Bristol, Wills Memorial Building; Queen's Road Bristol BS8 1RJ UK
| | - Gregory D. Edgecombe
- Department of Earth Sciences, The Natural History Museum; Cromwell Road London SW7 5BD UK
| | - Derek E. G. Briggs
- Department of Geology and Geophysics, Yale University; 210 Whitney Avenue New Haven CT 06511 USA
- Yale Peabody Museum of Natural History; 170 Whitney Avenue New Haven CT 06520 USA
- Departments of Ecology and Evolutionary Biology and Earth Sciences, University of Toronto; Toronto ON M5S 3B2 Canada
| | - Jakob Vinther
- School of Earth Sciences, University of Bristol, Wills Memorial Building; Queen's Road Bristol BS8 1RJ UK
- Royal Ontario Museum; 100 Queen's Park Toronto ON M5S 2C6 Canada
- School of Biological Sciences, University of Bristol; Life Sciences Building, 24 Tyndall Avenue Bristol BS8 1TQ UK
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23
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The Effect Of microbial Mats In The Decay Of Anurans With Implications For Understanding Taphonomic Processes In The Fossil Record. Sci Rep 2017; 7:45160. [PMID: 28338095 PMCID: PMC5364532 DOI: 10.1038/srep45160] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 02/20/2017] [Indexed: 11/18/2022] Open
Abstract
The pattern and sequence of the decomposition of the Pipidae African dwarf frog (Hymenochirus boettgeri) is tracked in an experiment with microbial mats in order to explore soft tissue preservation over three years. Frog decay in microbial mats is preceded by rapid entombment (25–30 days) and mediated by the formation of a sarcophagus, which is built by a complex microbial community. The frog carcasses maintained a variety of soft tissues for years. Labile organic structures show greater durability within the mat, cells maintain their general shape (bone marrow cells and adipocytes), and muscles and connective tissues (adipose and fibrous tendons) exhibit their original organic structures. In addition, other soft tissues are promptly mineralized (day 540) in a Ca-rich carbonate phase (encephalic tectum) or enriched in sulphur residues (integumentary system). The result is coherent with a bias in soft-tissue preservation, as some tissues are more likely to be conserved than others. The outcomes support observations of exceptionally preserved fossil anurans (adults and tadpoles). Decomposition in mats shows singular conditions of pH and dissolved oxygen. Mineralization processes could be more diverse than in simple heterotrophic biofilms, opening new taphonomic processes that have yet to be explored.
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