Q2. What are the future works in this paper?
The latter presenting the intriguing possibility that the diversification of marine ecosystems was on a single trajectory that peaked in the Devonian.
The Furongian (late Cambrian) Biodiversity Gap: Real or apparent?
TL;DR: The Furongian gap as mentioned in this paper is defined as the gap between the Cambrian Explosion and the Great Ordovician Biodiversification Event, exemplified by a marked drop in biodiversity.
About: This article is published in Palaeoworld.The article was published on 2019-03-01 and is currently open access. It has received 35 citations till now. The article focuses on the topics: Ordovician & Paleozoic.
Summary (2 min read)
2. Background
- Palaeontologists have long accepted that the fossil record is incomplete but nevertheless adequate to describe and understand the history of life on their planet.
- Some hundred years after publication of the 1st edition of Darwin’s influential work, interest intensified on the adequacy and quality of the fossil record as more complex and sophisticated analyses of the evolution of fossil organisms and their diversity were developed through deep time.
- Raup, in a succession of key papers, developed the concept of time-dependent and timeindependent biases (Raup, 1972, 1976a, 1976b).
- These key factors may provide some explanation for the current dearth of data from this critical interval.
4. Fact or artefact?
- Furongian rocks are known from all major Cambrian palaeocontinents and widely distributed in many regions, such as in Laurentia, South China, Siberia and Baltica.
- This is true for a number of classic areas of Cambrian research from western Gondwana, for example the Barrandian area of Bohemia, Spain and Morocco, together with parts of the Baltic (e.g., Estonia) where the Furongian is poorly represented or consists of shallow-water deposits that are poorly fossiliferous.
- In fact, total and SIB diversity follow comparable trajectories, which seems to fit to occurrence signal, while BC diversity reflects an independent pattern (Fig. 1).
- To avoid inconsistences generated by false positives, the authors ran a two-time data analysis from raw and generalized-differenced data for comparisons (see http://www.graemetlloyd.com/methgd.html for implementation).
- Evidence seems to suggest that, the overall observed diversity (in particular total diversity) may be driven by sampling, sampling does not account for the entire diversity signal; a biological signal is still legible in the fossil record.
5. Natural causes
- Diversity curves based on the Sepkoski Database indicate a high frequency of extinctions during the late Cambrian (Fig. 3).
- The frequency and magnitude of these events, especially when displayed as proportions of extinct genera, are impressive (see e.g., Melott and Bambach, 2012; Erlykin et al., 2018).
- Two globally significant carbon isotope excursions are recognized in the Furongian, the Steptoean Positive carbon Isotope Excursion in the Paibian Stage and the HEllnmaria — Red Tops Boundary Event (HERB) or Top of Cambrian Excursion (TOCE) in provisional Stage 10 (Zhu et al., 2006; Fig. 3 herein).
- The magnitude of the SPICE and the HERB Event in shale successions is, however, subdued compared to the δ13Ccarb excursions recorded in carbonate successions, and the δ13Corg signal is commonly half, or less than half, of the magnitude the δ13Ccarb signal (see Ahlberg et al., in press and references therein).
- The interpretation of the SPICE as a global anoxic event has, however, been questioned, because the presence of benthic faunal elements and bioturbation in almost all SPICE-related sections excludes widespread and persistent anoxia or euxinia, but rather suggest oxic or dysoxic sea floor conditions during most of the SPICE interval (Egenhoff et al., 2015; Wotte and Strauss, 2015).
6. Conclusions
- Currently there is marked interregnum in biodiversity between the high-profile, exceptionally-preserved biotas of the Cambrian Explosion, preserved across a number of Lagerstätten, and the four-fold increase in numbers of families, genera and species during the Great Ordovician Biodiversification Event.
- There are relatively few fossil collections, compared with older and younger strata, through this interval coupled with a lack of taxonomic work on its biotas.
- Extreme fluctuations are present in Furongian environments, providing a barrier to the expansion of the marine ecosystem and its biodiversity.
- That had to wait until the Early Ordovician.
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TL;DR: In this paper, the shape of recent biodiversity curves for Ordovician biotas have predictably converged promoting acceptance of discrete events, aligned with relatively few peaks and discrete drivers.
20 citations
TL;DR: In this paper, the authors explore these conditions using new and previously published Fe-speciation data from seven basins distributed across five paleocontinents representing a range of depositional conditions and reveal anoxia was a common and persistent feature of deeper-water environments and that it was generally absent from shallower-waters across this timespan.
18 citations
Cites background from "The Furongian (late Cambrian) Biodi..."
...Second, the interval is also a time of abnormally high rates of turnover in marine fauna (Bambach et al., 2004; Harper et al., 2019)....
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...2 in Harper et al. (2019) for a generalized facies map for this time)....
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...It should be noted that Harper et al. (2019) highlights the paucity of fossiliferous deposits and a lack of detailed taxonomic studies of Furongian strata as potential biases that contribute to the biodiversity patterns during this interval....
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...…feature of this time period is that it represents an evolutionary “plateau” between the rapid increases in biological diversity and complexity of the Cambrian Explosion that precedes it and the subsequent evolutionary radiation of the GOBE that followed (Bambach et al., 2004; Harper et al., 2019)....
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...The middle Cambrian to Early Ordovician is characterized by abnormally high rates of turnover in marine fauna (Bambach et al., 2004; Harper et al., 2019)....
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TL;DR: In this article , 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.
Abstract: 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.
7 citations
TL;DR: In this article , a selection of the most abundant acritarch taxa from the Cambrian and Ordovician of China was used to understand the evolution of the phytoplankton over the period.
Abstract: Palaeozoic acritarchs mostly represent organic-walled cysts of marine phytoplankton, and therefore, as primary producers, played an important role in the evolution of marine ecosystems. In this study, we use a selection of the most abundant acritarch taxa from the Cambrian and Ordovician of China to understand the evolution of the palaeoecological patterns of the phytoplankton over the period. The taxa are attributed to 40 easily distinguishable morphotypes, of which the precise palaeoenvironmental distribution from 60 localities is available. By placing the 40 morphotypes on inshore–offshore transects it can be concluded that acritarch microfloras were limited to inshore environments during the early Cambrian, and progressively extended from inshore environments to offshore marine habitats during the later parts of the Cambrian and towards the Early Ordovician, with a prominent shift near the Cambrian–Ordovician boundary, confirming the onset of the ‘Ordovician plankton revolution’. In addition, the acritarch morphotypes evolved from low-diversity assemblages in the early Cambrian, dominated by simple spherical forms with limited ornamentation and simple process structures, to highly diverse assemblages with very complex morphologies in the Early and Middle Ordovician. During the Ordovician, the complex acritarch assemblages occupied most marine habitats, with palaeoecological distribution patterns similar to modern dinoflagellates. This article is part of the theme issue ‘The impact of Chinese palaeontology on evolutionary research’.
7 citations
TL;DR: In this paper, the authors explore the Mule Spring Limestone of Nevada, which contains shallow water carbonate environments from the immediate aftermath of the regional archaeocyathan extinction and find evidence of sparse microbial-built leolites and some potentially poorly preserved metazoan organisms.
Abstract: Archaeocyathan sponges were the dominant metazoan framework builders during Series 2 of the Cambrian. After their near extinction during the Toyonian stage (middle Stage 4), this important ecological role was eventually filled by robustly skeletonized lithistid sponges. However, the exact timing of ecological restructuring is not well understood and was likely not contemporaneous across different paleocontinents. For example, reefs from the Wuliuan of China appear to show rapid replacement of archaeocyaths with lithistid sponges, yet the earliest occurrence of lithistids in Laurentia is not until the early Furongian. In this study, we explore the Mule Spring Limestone of Nevada, which contains shallow water carbonate environments from the immediate aftermath of the regional archaeocyathan extinction, for signs of reef-building activity. Within this formation, we find evidence of sparse microbial-built leolites and some potentially poorly preserved metazoan organisms. However, the totality of our field observations and thin-section point counts suggest that there was no substantial reef-building activity by either microbial or metazoan organisms within our study locality. Our data suggest the occurrence of a local reef eclipse during this interval for the locality investigated. We also incorporate geochemical proxies to determine paleoredox conditions, which suggest well-oxygenated marine conditions through the period of interest. Lack of hardground substrate is proposed as the cause for this gap in the reef record. These results show that a temporary loss of framework-building activity occurred after the regional extinction of archaeocyaths and demonstrates the ecological impact of losing framework builders on a reef environment.
6 citations
References
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Book•
03 Sep 2009
TL;DR: The "Penguin Classics" edition of "On the Origin of Species" as discussed by the authors contains an introduction and notes by William Bynum, and features a cover designed by Damien Hirst.
Abstract: Charles Darwin's seminal formulation of the theory of evolution, "On the Origin of Species" continues to be as controversial today as when it was first published. This "Penguin Classics" edition contains an introduction and notes by William Bynum, and features a cover designed by Damien Hirst. Written for a general readership, "On the Origin of Species" sold out on the day of its publication and has remained in print ever since. Instantly and persistently controversial, the concept of natural selection transformed scientific analysis about all life on Earth. Before the "Origin of Species", accepted thinking held that life was the static and perfect creation of God. By a single, systematic argument Darwin called this view into question. His ideas have affected public perception of everything from religion to economics. William Bynum's introduction discusses Darwin's life, the publication and reception of the themes of "On the Origin of Species", and the subsequent development of its major themes. The new edition also includes brief biographies of some of the most important scientific thinkers leading up to and surrounding the "Origin of Species", suggested further reading, notes and a chronology. Charles Darwin (1809-82), a Victorian scientist and naturalist, has become one of the most famous figures of science to date. The advent of "On the Origin of Species" by means of natural selection in 1859 challenged and contradicted all contemporary biological and religious beliefs. If you enjoyed "On the Origin of Species", you might like Darwin's "The Descent of Man", also available in "Penguin Classics".
7,487 citations
TL;DR: A history of sea-level fluctuations for the entire Paleozoic by using stratigraphic sections from pericratonic and cratonic basins is reconstructed, revealing a gradual rise through the Cambrian and a short-lived but prominent withdrawal in response to Hirnantian glaciation.
Abstract: Sea levels have been determined for most of the Paleozoic Era (542 to 251 million years ago), but an integrated history of sea levels has remained unrealized. We reconstructed a history of sea-level fluctuations for the entire Paleozoic by using stratigraphic sections from pericratonic and cratonic basins. Evaluation of the timing and amplitude of individual sea-level events reveals that the magnitude of change is the most problematic to estimate accurately. The long-term sea level shows a gradual rise through the Cambrian, reaching a zenith in the Late Ordovician, then a short-lived but prominent withdrawal in response to Hirnantian glaciation. Subsequent but decreasingly substantial eustatic highs occurred in the mid-Silurian, near the Middle/Late Devonian boundary, and in the latest Carboniferous. Eustatic lows are recorded in the early Devonian, near the Mississippian/Pennsylvanian boundary, and in the Late Permian. One hundred and seventy-two eustatic events are documented for the Paleozoic, varying in magnitude from a few tens of meters to ∼125 meters.
1,227 citations
Book•
01 Jan 2008
TL;DR: In this paper, the authors present an approach to multivariate data analysis for paleontological data, which is based on the allometric equation and a set of properties of the data.
Abstract: Preface. Acknowledgments. 1 Introduction. 1.1 The nature of paleontological data. 1.2 Advantages and pitfalls of paleontological data analysis. 1.3 Software. 2 Basic statistical methods. 2.1 Introduction. 2.2 Statistical distributions. 2.3 Shapiro-Wilk test for normal distribution. 2.4 F test for equality of variances. 2.5 Student's t test and Welch test for equality of means. 2.6 Mann-Whitney U test for equality of medians. 2.7 Kolmogorov-Smirnov test for equality of distributions. 2.8 Permutation and resampling. 2.9 One-way ANOVA. 2.10 Kruskal-Wallis test. 2.11 Linear correlation. 2.12 Non-parametric tests for correlation. 2.13 Linear regression. 2.14 Reduced major axis regression. 2.15 Nonlinear curve fitting. 2.16 Chi-square test. 3 Introduction to multivariate data analysis. 3.1 Approaches to multivariate data analysis. 3.2 Multivariate distributions. 3.3 Parametric multivariate tests. 3.4 Non-parametric multivariate tests. 3.5 Hierarchical cluster analysis. 3.5 K-means cluster analysis. 4 Morphometrics. 4.1 Introduction. 4.2 The allometric equation. 4.3 Principal components analysis (PCA). 4.4 Multivariate allometry. 4.5 Discriminant analysis for two groups. 4.6 Canonical variate analysis (CVA). 4.7 MANOVA. 4.8 Fourier shape analysis. 4.9 Elliptic Fourier analysis. 4.10 Eigenshape analysis. 4.11 Landmarks and size measures. 4.12 Procrustean fitting. 4.13 PCA of landmark data. 4.14 Thin-plate spline deformations. 4.15 Principal and partial warps. 4.16 Relative warps. 4.17 Regression of partial warp scores. 4.18 Disparity measures. 4.19 Point distribution statistics. 4.20 Directional statistics. Case study: The ontogeny of a Silurian trilobite. 5 Phylogenetic analysis. 5.1 Introduction. 5.2 Characters. 5.3 Parsimony analysis. 5.4 Character state reconstruction. 5.5 Evaluation of characters and tree topologies. 5.6 Consensus trees. 5.7 Consistency index. 5.8 Retention index. 5.9 Bootstrapping. 5.10 Bremer support. 5.11 Stratigraphical congruency indices. 5.12 Phylogenetic analysis with Maximum Likelihood. Case study: The systematics of heterosporous ferns. 6 Paleobiogeography and paleoecology. 6.1 Introduction. 6.2 Diversity indices. 6.3 Taxonomic distinctness. 6.4 Comparison of diversity indices. 6.5 Abundance models. 6.6 Rarefaction. 6.7 Diversity curves. 6.8 Size-frequency and survivorship curves. 6.9 Association similarity indices for presence/absence data. 6.10 Association similarity indices for abundance data. 6.11 ANOSIM and NPMANOVA. 6.12 Correspondence analysis. 6.13 Principal Coordinates analysis (PCO). 6.14 Non-metric Multidimensional Scaling (NMDS). 6.15 Seriation. Case study: Ashgill brachiopod paleocommunities from East China. 7 Time series analysis. 7.1 Introduction. 7.2 Spectral analysis. 7.3 Autocorrelation. 7.4 Cross-correlation. 7.5 Wavelet analysis. 7.6 Smoothing and filtering. 7.7 Runs test. Case study: Sepkoski's generic diversity curve for the Phanerozoic. 8 Quantitative biostratigraphy. 8.1 Introduction. 8.2 Parametric confidence intervals on stratigraphic ranges. 8.3 Non-parametric confidence intervals on stratigraphic ranges. 8.4 Graphic correlation. 8.5 Constrained optimisation. 8.6 Ranking and scaling. 8.7 Unitary Associations. 8.8 Biostratigraphy by ordination. 8.9 What is the best method for quantitative biostratigraphy?. Appendix A: Plotting techniques. Appendix B: Mathematical concepts and notation. References. Index
867 citations
University of California, Santa Barbara1, Humboldt University of Berlin2, University of Southern California3, University of Chicago4, University of Erlangen-Nuremberg5, University of South Florida6, Yale University7, University of Cincinnati8, University of Georgia9, Syracuse University10, Smithsonian Institution11, Harvard University12, Natural History Museum13, Texas A&M University14, Pennsylvania State University15, University of Wisconsin-Madison16, Aix-Marseille University17, California State University, Fullerton18, University of California, Santa Cruz19, College of William & Mary20, University of Colorado Boulder21, Duke University22, Slovak Academy of Sciences23, University of North Carolina at Wilmington24
TL;DR: In this paper, a new data set of fossil occurrences representing 3.5 million specimens was presented, and it was shown that global and local diversity was less than twice as high in the Neogene as in the mid-Paleozoic.
Abstract: It has previously been thought that there was a steep Cretaceous and Cenozoic radiation of marine invertebrates. This pattern can be replicated with a new data set of fossil occurrences representing 3.5 million specimens, but only when older analytical protocols are used. Moreover, analyses that employ sampling standardization and more robust counting methods show a modest rise in diversity with no clear trend after the mid-Cretaceous. Globally, locally, and at both high and low latitudes, diversity was less than twice as high in the Neogene as in the mid-Paleozoic. The ratio of global to local richness has changed little, and a latitudinal diversity gradient was present in the early Paleozoic.
650 citations
TL;DR: In this paper, a new global classification of the Ordovician System into three series and seven stages has been proposed, based on a variety of biostratigraphic data.
Abstract: The extensive work carried out during more than a decade by the International Subcommission on Ordovician Stratigraphy has resulted in a new global classification of the Ordovician System into three series and seven stages. Formal Global Boundary Stratotype Section and Points (GSSPs) for all stages have been selected and these and the new stage names have been ratified by the International Commission on Stratigraphy. Based on a variety of biostratigraphic data, these new units are correlated with chronostratigraphic series and stages in the standard regional classifications used in the UK, North America, Baltoscandia, Australia, China, Siberia and the Mediterranean-North Gondwana region. Furthermore, based mainly on graptolite and conodont zones, the Ordovician is subdivided into 20 stage slices (SS) that have potential for precise correlations in both carbonate and shale facies. The new chronostratigraphic scheme is also tied to a new composite δ13C curve through the entire Ordovician.
563 citations