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Journal ArticleDOI

The Furongian (late Cambrian) Biodiversity Gap: Real or apparent?

01 Mar 2019-Palaeoworld (Elsevier)-Vol. 28, pp 4-12

AbstractTwo major, extended diversifications punctuated the evolution of marine life during the Early Palaeozoic. The interregnum, however, between the Cambrian Explosion and the Great Ordovician Biodiversification Event, is exemplified by the Furongian Gap when there was a marked drop in biodiversity. It is unclear whether the gap is apparent, due to sampling failure or lack of rock, or real — associated with unique and fluctuating environments, a distinctive palaeogeography and extreme climates during the late Cambrian. Indications suggest that there has been little attention paid to this interval compared with those below and above, while some of the classical areas for Cambrian research, such as Bohemia, have poor coverage through the Furongian. Moreover, based on information available in databases and the literature, together with the ghost ranges of many higher taxa through the Furongian, data suggest that biodiversity in this stage has been significantly underestimated. Emphasis, to date, has been placed on widespread, deeper-water dark shale facies of the interval, with generally low diversity faunas, whereas shallow-water communities have often been neglected.

Topics: Ordovician (53%), Paleozoic (51%)

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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Citation for published item:
Harper, David A.T. and Topper, Timothy P. and Cascales-Minana, Borja and Servais, Thomas and Zhang,
Yuan-Dong and Ahlberg, Per (2019) 'The Furongian (late Cambrian) Biodiversity Gap : real or apparent?',
Palaeoworld., 28 (1-2). pp. 4-12.
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Accepted Manuscript
Title: The Furongian (late Cambrian) Biodiversity Gap: Real
or apparent?
Authors: David A.T. Harper, Timothy P. Topper, Borja
Cascales-Mi
˜
nana, Thomas Servais, Yuan-Dong Zhang, Per
Ahlberg
PII: S1871-174X(18)30162-8
DOI: https://doi.org/10.1016/j.palwor.2019.01.007
Reference: PALWOR 492
To appear in: Palaeoworld
Received date: 11 November 2018
Revised date: 19 January 2019
Accepted date: 29 January 2019
Please cite this article as: Harper, David A.T., Topper, Timothy P., Cascales-
Mi
˜
nana, Borja, Servais, Thomas, Zhang, Yuan-Dong, Ahlberg, Per, The
Furongian (late Cambrian) Biodiversity Gap: Real or apparent?.Palaeoworld
https://doi.org/10.1016/j.palwor.2019.01.007
This is a PDF file of an unedited manuscript that has been accepted for publication.
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The Furongian (late Cambrian) Biodiversity Gap: Real or apparent?
David A.T. Harper
a, b
*, Timothy P. Topper
c, d
, Borja Cascales-Miñana
e
, Thomas
Servais
e
, Yuan-Dong Zhang
f, g
, Per Ahlberg
b
a
Palaeoecosystems Group, Department of Earth Sciences, Durham University, Durham
DH1 3LE, UK
b
Department of Geology, Lund University, SE-223 62 Lund, Sweden
c
Shaanxi Key Laboratory of Early Life and Environments, State Key Laboratory of
Continental Dynamics and Department of Geology, Northwest University, Xian
710069, China
d
Swedish Museum of Natural History, P.O. Box 50007, SE-104 05 Stockholm, Sweden
e
CNRS, Université Lille, UMR 8198 - Evo-Eco-Paleo F-59000 Lille, France
f
CAS Key Laboratory of Economic Geology and Stratigraphy, Nanjing Institute of
Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road,
Nanjing 210008, China
g
Center for Excellence in Life and Palaeoenvironment, Nanjing Institute of Geology
and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing
210008, China
* Corresponding author. E-mail address: david.harper@durham.ac.uk
Abstract
Two major, extended diversifications punctuated the evolution of marine life
during the Early Palaeozoic. The interregnum, however, between the Cambrian
Explosion and the Great Ordovician Biodiversification Event, is exemplified by the
Furongian Gap when there was a marked drop in biodiversity. It is unclear whether the
gap is apparent, due to sampling failure or lack of rock, or real associated with unique
ACCEPTED MANUSCRIPT

and fluctuating environments, a distinctive palaeogeography and extreme climates
during the late Cambrian. Indications suggest that there has been little attention paid to
this interval compared with those below and above, while some of the classical areas
for Cambrian research, such as Bohemia, have poor coverage through the Furongian.
Moreover, based on information available in databases and the literature, together with
the ghost ranges of many higher taxa through the Furongian, data suggest that
biodiversity in this stage has been significantly underestimated. Emphasis, to date, has
been placed on widespread, deeper-water dark shale facies of the interval, with
generally low diversity faunas, whereas shallow-water communities have often been
neglected.
Keywords: Cambrian; GOBE; biodiversity; palaeoenvironments; extinctions;
radiations
ACCEPTED MANUSCRIPT

1. Introduction
The fossil record is probably more gaps than record, expressed a century ago as
‘the skimmings of the pot of life’ (Huxley, 1862), and noted some decades ago as poorly
sampled, with perhaps only 10-15% of genera are known (Boucot, 2000) and poorly
taxonomically-studied (Boucot, 1983). Some gaps, for example Romer’s Gap in
tetrapod evolution during the latest Devonian and Early Carboniferous are being filled
by many new body-fossil discoveries (e.g., Clack et al., 2016), exemplifying previous
lack of sampling and taxonomic study. The late Cambrian (Furongian) interval is
another such biodiversity or evolutionary gap that to date has received comparatively
little attention. Did a lack of rock, fossils or inadequate sampling break the continuity
between the Cambrian Explosion and the Great Ordovician Biodiversification Event or
were conditions simply too inhospitable for marine organisms to flourish?
2. Background
Palaeontologists have long accepted that the fossil record is incomplete but
nevertheless adequate to describe and understand the history of life on our planet.
Charles Darwin, in his first edition (Darwin, 1859), devoted two chapters to geology
and palaeontology in his ‘Origin of Species’, one ‘On the Imperfection of the
Geological Record’ (chapter nine) and the other ‘On the Geological Succession of
Organic Beings’ (chapter ten). In the first he noted such imperfections do not preserve
the entire continuity of life, a ‘finely-graduated organic chain’, providing a serious
objection to the theory of evolution; we thus lack many intermediate and transitional
forms. And in the second chapter Darwin highlighted that fossils were generally
preserved during intervals of subsidence (increased rates of sedimentation), with blank
intervals occurring when the seabed was either stationary or rising. In his summary of
the two chapters, Darwin emphasised that only a small portion of the globe had been
explored, only specific organisms are preserved as fossils, and that museum collections
are an inadequate proxy for the true diversity of the fossil record (‘absolutely as nothing
as compared with the number of generations which must have passed away even during
a single formation’). Nevertheless, old forms were supplanted by new and improved
forms as a product of variation and natural selection. One year later John Phillips (1860)
published the first comprehensive inventory of fossil range data in his ‘Life on Earth’.
In his opus, Phillips used the ranges of fossils to define his Palaeozoic, Mesozoic and
ACCEPTED MANUSCRIPT

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Abstract: Recent molecular clock data suggest with high probability a Cambrian origin of Embryophyta (also called land plants), indicating that their terrestrialization most probably started about 500 Ma. The fossil record of the ‘Cambrian Explosion’ was limited to marine organisms and not visible in the plant fossil record. The most significant changes in early land plant evolution occurred during the Ordovician. For instance, the earliest bryophyte-like cryptospores and the oldest fragments of the earliest land plants are from the Middle and Late Ordovician, respectively. Organic geochemistry studies on biomarker compositions hint at a transition from green algae to land plants during the ‘Great Ordovician Biodiversification Event’ (GOBE). The colonization of the terrestrial realms by land plants clearly had an impact on marine ecosystems. Interactions between the terrestrial and marine biospheres have been proposed and the radiation of land plants potentially impacted on CO2 and O2 concentrations and on global climate. In addition, the shift of strontium isotopes during the Ordovician is probably linked to changing terrestrial landscapes, affected by the first massive land invasion of eukaryotic terrestrial life. The land plants seem unaffected by the first global mass extinction at the end of the Ordovician that eliminated many marine invertebrate taxa.

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Abstract: The middle to later Cambrian (Drumian-Jiangshanian Ages, 505–490 Ma) was a time of unique evolutionary dynamics that remain enigmatic. This interval records unusually high rates of faunal turnover that produced a “plateau” within the broader trajectory of rapidly increasing biodiversity seen across the Cambrian Explosion and Great Ordovician Biodiversification Event (GOBE). The oceans during this time are generally thought to have been less oxygenated than later in the Phanerozoic, yet knowledge of oceanic redox structure and the influence this exerted upon the biosphere remains limited. Importantly, this interval also encompasses two large carbon cycle perturbations—the DICE and SPICE events— that are thought to involve the expansion of anoxic and, more specifically euxinic regions in the ocean. Despite this supposition, direct characterization of redox conditions across this time remains limited. Here we explore these conditions using new and previously published Fe-speciation data from seven basins distributed across five paleocontinents representing a range of depositional conditions. Our analysis reveals anoxia was a common and persistent feature of deeper-water environments and that it was generally absent from shallower-waters across this timespan. An exception to this broad pattern is seen during the SPICE when these deeper-water anoxic conditions expanded into shallower-water environments. These anoxic conditions were dominantly ferruginous and rare instances of euxinia were spatiotemporally limited to environments of high productivity, low clastic sedimentation and high sulfate availability within a generally low-sulfate ocean. Intriguingly, during these events faunal turnover was concentrated in inner-shelf areas suggesting a mechanistic link to the variable redox conditions characteristic of these environments. More broadly this instability in nearshore environments appears a likely cause of the high rates of faunal turnover seen across the later Cambrian and into the Early Ordovician, but further detailed paleontological and redox investigation of these environments are needed to adequately evaluate this view.

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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)....

    [...]

  • ...2 in Harper et al. (2019) for a generalized facies map for this time)....

    [...]

  • ...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....

    [...]

  • ...…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)....

    [...]

  • ...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)....

    [...]


Journal ArticleDOI
Abstract: A review of biodiversity curves of marine organisms indicates that, despite fluctuations in amplitude (some large), a large-scale, long-term radiation of life took place during the early Palaeozoic Era; it was aggregated by a succession of more discrete and regionalized radiations across geographies and within phylogenies. This major biodiversification within the marine biosphere started during late Precambrian time and was only finally interrupted in the Devonian Period. It includes both the Cambrian Explosion and the Great Ordovician Biodiversification Event. The establishment of modern marine ecosystems took place during a continuous chronology of the successive establishment of organisms and their ecological communities, developed during the ‘Cambrian substrate revolution’, the ‘Ordovician plankton revolution’, the ‘Ordovician substrate revolution’, the ‘Ordovician bioerosion revolution’ and the ‘Devonian nekton revolution’. At smaller scales, different regional but important radiations can be recognized geographically and some of them have been identified and named (e.g. those associated with the ‘Richmondian Invasion’ during Late Ordovician time in Laurentia and the contemporaneous ‘Boda event’ in parts of Europe and North Africa), in particular from areas that were in or moved towards lower latitudes, allowing high levels of speciation on epicontintental seas during these intervals. The datasets remain incomplete for many other geographical areas, but also for particular time intervals (e.g. during the late Cambrian ‘Furongian Gap’). The early Palaeozoic biodiversification therefore appears to be a long-term process, modulated by bursts in significant diversity and intervals of inadequate data, where its progressive character will become increasingly clearer with the availability of more complete datasets, with better global coverage and more advanced analytical techniques.

8 citations


Cites background from "The Furongian (late Cambrian) Biodi..."

  • ...The Furongian Biodiversity Gap has been recently noted in a number of papers (e.g. Servais & Harper, 2018) and examined in detail (Harper et al. 2019b)....

    [...]

  • ...Some of the subsequent benchmark studies during the twentieth and twenty-first centuries have been recently charted by Harper et al. (2019b) in connection with unravelling the Furongian Biodiversity Gap; the studies of Newell (1959), Raup (1972) and Valentine (1973) have been particularly…...

    [...]

  • ...Harper et al. (2019b) have discussed this gap in detail, concluding that diversity has been significantly underestimated by a paucity of examined rock, compounded by a distinctive palaeogeography, extreme climates and fluctuating environments....

    [...]

  • ...…with exceptional preservation, such as the Burgess Shale in the Canadian Rocky Mountains (e.g. Briggs et al. 1994; Erwin & Valentine, 2013; Briggs, 2015), Chengjiang in South China (e.g. Hou et al. 2017; Yang et al. 2018), Sirius Passet in North Greenland (e.g. Harper et al. 2019a) and others....

    [...]


Journal ArticleDOI
Abstract: The Steptoean Positive Isotopic Carbon Excursion (SPICE) is a prominent chemostratigraphic feature in the Lower Paleozoic. It has been used to correlate Upper Cambrian carbonate strata globally, and is cited as intimately linked to the Crepicephalus-Aphelaspis trilobite extinction event and the Sauk II-Sauk III megasequence transition. Despite the global nature of the SPICE event, regional/local conditions serve as a control on the expression of the SPICE event in the rock record. In light of this, and to better understand how reliable the SPICE event is as a chemostratigraphic tool for correlation, we have created the “SPICEraq,” a database comprising 78 SPICE-bearing sections containing 6669 individual δ13C analyses. In this study, we quantitatively evaluate the variability in SPICE records, and document that, while the excursion is a global signature, its stratigraphic expression is influenced by such conditions as paleolatitude, paleocontinent, water depth, and facies. While the magnitude of the SPICE excursion is generally consistent (an ~4‰ increase), the peak δ13C values are quite variable (ranging from +0.35 to +5.87‰). Specifically, sections located between 30 and 60°S paleolatitude ca. 500 Ma record δ13C values ~1 to 2‰ lower than those from lower paleolatitudes. Sections deposited in shallow water depths and facies also record lower δ13C values than intermediate and deep-water facies; the deep-water facies exhibit the most 13C-enriched carbonates at the peak of the SPICE and post-excursion. The stratigraphic thickness of the excursion varies widely, ranging from

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References
More filters

Book
03 Sep 2009
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".

7,384 citations


Journal ArticleDOI
03 Oct 2008-Science
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.

1,022 citations


Book
01 Jan 2008
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

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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.

585 citations


Journal ArticleDOI
01 Mar 2009-Lethaia
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.

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Related Papers (5)
Frequently Asked Questions (2)
Q1. What are the contributions in this paper?

Indications suggest that there has been little attention paid to this interval compared with those below and above, while some of the classical areas for Cambrian research, such as Bohemia, have poor coverage through the Furongian. Moreover, based on information available in databases and the literature, together with the ghost ranges of many higher taxa through the Furongian, data suggest that biodiversity in this stage has been significantly underestimated. 

The latter presenting the intriguing possibility that the diversification of marine ecosystems was on a single trajectory that peaked in the Devonian.