Phanerozoic Diversity Research Articles

Coronene, mercury, and biomarker data support a link between extinction magnitude and volcanic intensity in the Late Devonian

The Late Devonian biodiversity crisis, one of the big five Phanerozoic diversity depletions, is composed of a series of extinction events broadly coincident with the invasion of land by plants and vertebrates. These extinctions may have been triggered by volcanism, as sedimentary mercury enrichments are associated with the two main extinctions, the Kellwasser and Hangenberg crises. However, the sources of this mercury and its relation to volcanic style are not known. Furthermore, any links between the magnitudes of volcanic emissions and biodiversity loss have not been explored. To address these issues, we develop a new suite a geochemical data from shallow water sedimentary rocks in France, Belgium, and China for three Late Devonian crises – the Kellwasser and Hangenberg events, as well as for the preceding Frasnian extinction. We report paired coronene – mercury data as a refined proxy for large igneous province (LIP) emplacement, and we use cadalene and dibenzofuran biomarkers as proxies for terrestrial ecological disturbance. Coronene is a highly condensed six-ring polycyclic aromatic hydrocarbon (PAH), which requires significantly higher energy to form as compared to smaller PAHs; coronene enrichment has been found only in LIP volcanic emission and projectile impact events. Our data show that coronene and mercury coincidentally peaked at only the environmental and biotic events, demonstrating that pulses of LIP volcanism are tightly associated with the Late Devonian crises. In addition, mercury concentration is highly correlated with cadalene and dibenzofuran abundance during the events only in nearshore settings, indicating fluxes of soil erosion. Finally, we observe a correlation between coronene index and extinction magnitude for the three events, suggesting a link between temperatures of sills and lavas during LIP emplacement, pressure of evolved volatiles, and global climatic effects.

Response by Shanan E. Peters for the presentation of the 2014 Charles Schuchert Award of the Paleontological Society

Thank you Michael, for your kind words, and thank you to the Paleontological Society for this recognition. It is a humbling privilege to have my name appended to such a distinguished list of previous awardees. It is also thrilling that this award bears the name of the remarkable Ohio-born paleontologist, Charles Schuchert, who began his pursuit of paleontology in much the same way that this Ohio boy did—plucking fossils from the gray slopes of the Cincinnatian. Shanan E. Peters Some eleven years ago, in his acceptance speech for this same award, Steven Holland acknowledged the Paleobiology Database and the vision of John Alroy and Charles Marshall in creating it. Steve predicted then that beyond the analysis of Phanerozoic diversity, the Paleobiology Database would become an integral part of our field programs because it would “ensure that we build upon the data of the generations that have come before us and that our data are preserved for the generations that follow.” Eleven years …

Calibrating the Ordovician Radiation of marine life: implications for Phanerozoic diversity trends.

It has long been suspected that trends in global marine biodiversity calibrated for the Phanerozoic may be affected by sampling problems. However, this possibility has not been evaluated definitively, and raw diversity trends are generally accepted at face value in macroevolutionary investigations. Here, we analyze a global-scale sample of fossil occurrences that allows us to determine directly the effects of sample size on the calibration of what is generally thought to be among the most significant global biodiversity increases in the history of life: the Ordovician Radiation. Utilizing a composite database that includes trilobites, brachiopods, and three classes of molluscs, we conduct rarefaction analyses to demonstrate that the diversification trajectory for the Radiation was considerably different than suggested by raw diversity time-series. Our analyses suggest that a substantial portion of the increase recognized in raw diversity depictions for the last three Ordovician epochs (the Llandeilian, Caradocian, and Ashgillian) is a consequence of increased sample size of the preserved and catalogued fossil record. We also use biometric data for a global sample of Ordovician trilobites, along with methods of measuring morphological diversity that are not biased by sample size, to show that morphological diversification in this major clade had leveled off by the Llanvirnian. The discordance between raw diversity depictions and more robust taxonomic and morphological diversity metrics suggests that sampling effects may strongly influence our perception of biodiversity trends throughout the Phanerozoic.

Phanerozoic diversity and neutral theory

AbstractAlthough Phanerozoic increases in the global richness, local richness, and evenness of marine invertebrates are well documented, a common explanation for these patterns has been difficult to identify. Evidence is presented here from marine invertebrate communities that there is a Phanerozoic increase in the fundamental biodiversity number (θ), which describes diversity and relative abundance distributions in neutral ecological theory. If marine ecosystems behave according to the rules of Hubbell’s Neutral Theory of Biodiversity and Biogeography, the Phanerozoic increase inθsuggests three possible mechanisms for the parallel increases in global richness, local richness, and evenness: (1) an increase in the per-individual probability of speciation, (2) an increase in the area occupied by marine metacommunities, and (3) an increase in the density (per-area abundance) of marine organisms. Because speciation rates have declined over time and because there is no clear evidence for an increase in metacommunity area through the Phanerozoic, the most likely of these is an increase in the spatial density of marine invertebrates over the Phanerozoic, an interpretation supported by previous studies of fossil abundance. This, coupled with a Phanerozoic rise in body size, suggests that an increase in primary productivity through time is the primary cause of Phanerozoic increases inθ, global richness, local richness, local evenness, abundance, and body size.

The Mesozoic return of Paleozoic faunal constituents: A decoupling of taxonomic and ecological dominance during the recovery from the end-Permian mass extinction

Phanerozoic diversity curves illustrate that the transition from taxonomic dominance of the Paleozoic Fauna to taxonomic dominance of the Modern Fauna is coincident with the Permo–Triassic boundary. Although a corresponding transition in ecological dominance must have occurred, its timing is unclear. One way to assess ecological dominance during the Early-Middle Triassic recovery interval is through the study of bioclastic accumulations. Bioclastic accumulations from the Early Triassic are largely dominated by constituents of the Modern Fauna. In this study, we examined bioclastic accumulations from the Middle Triassic, the interval after the environmental stress associated with the end-Permian extinction abated. Bioclastic accumulations from Panthalassan deposits (Ladinian portion of the Liard Formation at Williston Lake, Canada) and Tethyan deposits (Anisian–Ladinian Muschelkalk Group, Germany) were examined. Although the most common shell bed-producer differed between the two sites (bivalves, constituents of the Modern Fauna, in Germany and brachiopods, constituents of the Paleozoic Fauna, in Canada), both sites, though geographically disparate, contained significant crinoidal bioclastic accumulations (encrinites). Crinoids, like many constituents of the Paleozoic Fauna, suffered drastic diversity losses at the end-Permian mass extinction and maintained relatively low diversity through the Middle Triassic. Despite reduced diversity, bioclastic accumulations show that crinoids regained some measure of ecologic dominance in the Middle Triassic. In addition, brachiopods, another constituent of the Paleozoic Fauna that suffered severe diversity losses at the end-Permian extinction, regained at minimum local ecological dominance in the Middle Triassic of Panthalassa. These data demonstrate that the transition to Modern faunal taxonomic dominance was decoupled from the transition to Modern faunal ecological dominance.

The Phanerozoic Diversity of Agglutinated Foraminifera: Origination and Extinction Rates

New diversity curves for agglutinated foraminiferal genera are presented based on the stratigraphic ranges of 764 genera distributed over the 91 Phanerozoic chronostratigraphic subdivisions given in the ICS timescale. The data set for this analysis is based on the stratigraphic ranges of agglutinated genera published in Foraminiferal Genera and their Classifi− cation, 218 of which have been modified based upon subsequently published studies and new observations. Additionally, a total of 136 genera have been newly described or reinstated subsequent to the publication of Foraminiferal Genera and their Classification. The revision of stratigraphic ranges is part of the effort by the Grzybowski Foundation’s Interna− tional Working Group on Foraminiferal Classification to compile a new Catalogue of Agglutinated Foraminiferal Gen− era. The mean standing diversity of agglutinated foraminiferal genera was compiled by counting the number of boundary crossers rather than the number of genera in each stage. This diversity curve displays a general upward trend throughout the Phanerozoic, punctuated by peaks and troughs of variable magnitude. The curve shows a period of initial radiation from the Early Cambrian to the Early Silurian, followed by a plateau to the Late Permian. The Permian/Triassic and the Triassic/Jurassic boundaries are characterised by small dips in the diversity record. The Jurassic begins with an exponen− tial rise in mean standing diversity that continues to the Cenomanian. The Cenomanian to Holocene record of mean stand− ing diversity is characterised by four peaks and troughs that are roughly in line with the cycles of global climate, with re− ductions in diversity in the end−Cenomanian, end−Cretaceous, and end−Miocene. Excluding modern values, the Phanero− zoic maximum in the number of genera with a fossil record is observed in the Cenomanian, whereas the maximum Phanerozoic mean standing diversity is observed in the Langhian stage of the Miocene. The highest per−capita origination rates are observed in the Hettangian, Dapingian, Pleistocene, and Sheinwoodian (mid−Silurian). Linear regression analy− sis of the origination rates reveals a decrease towards the Holocene, in agreement with findings of Raup and Sepkoski. The highest per−capita extinction rates are observed in the Messinian, late Silurian (Gorstian), Hirnantian (latest Ordovi− cian), and Maastrichtian. The background extinction rate shows an increasing trend towards the Recent, which is in dis− agreement with the findings of Raup and Sepkoski. We attribute this apparent discrepancy to the Late Cretaceous to Palaeogene extinctions of shallower−water larger agglutinates and the pull of the end−Miocene extinction event. Key wor ds: Agglutinated foraminifera, phanerozoic, biodiversity, extinction, origination.

Do new reconstructions clarify the relationships between the Phanerozoic diversity dynamics of marine invertebrates and long-term eustatic trends?

A relationship between global sea levels and the diversity of marine invertebrates throughout the Phanerozoic remains an urgent matter for debates. Its recognition depends on a proper selection of diversity and eustatic curves. A comparison of changes in the revised sample-standardized generic diversity and long-term global sea-level changes provides a weaker evidence for a direct covarying relationship than established earlier, although the eustatic control on diversity dynamics of marine invertebrates was important during ∼74% of the Phanerozoic. Multiple causation of biodiversity changes, data bias, erroneous reconstructions, and conceptual misinterpretations are likely explanations of observed difference between the new biodiversity and eustatic curves.

Marine mammals through time: when less is more in studying palaeodiversity

The validity of biological explanations of patterns of palaeodiversity has been called into question owing to an apparent correlation of diversity with the amount of sedimentary rock preserved. However, this claim has largely been based on comprehensive estimates of global marine Phanerozoic diversity, thus raising the question of whether a similar bias applies to the records of smaller, well-defined taxonomic groups. Here, new data on European Caenozoic marine sedimentary rock outcrop area are presented and compared with European occurrences of three groups of marine mammals (cetaceans, pinnipedimorphs and sirenians). Limited evidence was found for a correlation of outcrop area with marine mammal palaeodiversity. In addition, similar patterns were identified in the cetacean and pinnipedimorph diversity data. This may point to the preservation of a genuine biological signal not overwhelmed by geological biases in the marine mammal diversity data, and opens the door to further analyses of both marine mammal evolution and geological bias in other small and well-defined groups of taxa.

Are global Phanerozoic marine diversity curves truly global? A study of the relationship between regional rock records and global Phanerozoic marine diversity

The consensus view that the amount of rock available for sampling does not significantly and systematically bias Phanerozoic marine diversity patterns has broken down. How changes in rock availability and sampling intensity affect our estimates of past biodiversity has been investigated with a variety of new approaches. A number of proxies for the amount of rock available for sampling have been used, but most of these proxies do not rely directly on evidence from large-scale geological maps (maps that cover small areas) and accompanying memoirs. Most previous map-based studies focused on single regions or relied on small-scale synoptic maps. We collected data from published geological maps and memoirs from western Europe, Australia, and Chile, which we combined with COSUNA data from the United States to generate the first multiregional data set for investigating whether the global Phanerozoic marine diversity record is a true global record, or is instead biased toward North America and Western Europe as has long been suspected. Both short and long-term trends in variation in the amount of outcrop display limited correlation among the regions studied. A series of diversification models obtained better matches to observed fossil diversity from the European and U.S. records than for the Chilean and Australian records, further supporting suspicions that the global Phanerozoic diversity curve is disproportionately influenced by European and U.S. fossil data. These results indicate that future research into Phanerozoic marine diversity patterns should not continue to apply global eustatic curves as a proxy for rock at outcrop, but should use regional data on rock occurrence.

The Darwinian dilemma of the first species and the principle of pseudo-monophyly of Phanerozoic diversity

The Darwinian dilemma of the first species and the principle of pseudo-monophyly of Phanerozoic diversity

Comment on "Statistical Independence of Escalatory Ecological Trends in Phanerozoic Marine Invertebrates"

The analysis of Madin et al. (Reports, 12 May 2006, p. 897) of Phanerozoic diversity failed to support expected correlations between carnivores and noncarnivores, leading the authors to reject escalation as an important macroevolutionary process. The test, however, is based on a flawed model of causality, and the ecological groups are improperly delineated with regard to the hypothesis.

Phanerozoic history of deep-sea trace fossils

Abstract The Phanerozoic diversity of deep-sea trace fossils, based on 151 flysch formations, displays distinct, non-linear changes through the Phanerozoic, with peaks in the Ordovician-Early Silurian and Early Carboniferous, lowered in the Permian-older Late Jurassic, a peak in the Tithonian-Aptian, lowered in the Albian, and the maximum in the Eocene. The contribution of graphoglyptids in trace fossil assemblages rises gradually up to the end of the Cretaceous, shows a peak in the Palaeocene-Eocene but a depression in the Oligocene. All the changes were probably influenced by competition for food and food supply, bottom water temperatures and oxygenation, and frequency of flysch habitats. There is no clear influence of major biotic crises (Ordovician/Silurian, Cretaceous/Tertiary, Palaeocene/Eocene) on the diversity of deep trace fossils, except the Eocene/Oligocene crisis.

The multiple scales of biodiversity

The claim that measures of global biodiversity dynamics are meaningless is based upon several methodological problems, including underrepresentation of tropical regions in “global” Phanerozoic data sets, inaccuracies in taxonomic data, non-equivalence of higher taxa among groups of organisms, and uneven sampling intensity across groups, environments, and time intervals. Some of these problems are inherent in the fossil record, whereas others lie in documentation and interpretation of the subject. But the subject of global biodiversity is perfectly legitimate, even if problems persist in evaluating its full history. Moreover, recognition of the methodological problems has resulted in notable improvements in the Phanerozoic diversity database (e.g., Adrain and Westrop 2000; Alroy et al. 2001).

Conversations about Phanerozoic global diversity

The emergence of Phanerozoic global diversity as a central theme of investigation has resulted from a confluence of factors, including the assembly by several researchers of global taxonomic databases; the advent of computers, which permitted construction and analysis of global Phanerozoic diversity trajectories; and the recognition that Phanerozoic diversity trends are important bellwethers of the evolutionary processes that cause biotic transitions. Despite the enormous progress in the measurement and interpretation of Phanerozoic diversity over the past quarter century, much of which has been reported in Paleobiology, these studies have collectively generated at least as many new questions as they have answered—arguably the mark of an area of inquiry that continues to be vital. In this essay, I discuss several outstanding issues in the investigation of Phanerozoic diversity, ranging from the viability of literature-derived databases for investigating global diversity trends, to the biological significance of the myriad biotic transitions that have taken place throughout the Phanerozoic.

Conversations about Phanerozoic global diversity

The emergence of Phanerozoic global diversity as a central theme of investigation has resulted from a confluence of factors, including the assembly by several researchers of global taxonomic databases; the advent of computers, which permitted construction and analysis of global Phanerozoic diversity trajectories; and the recognition that Phanerozoic diversity trends are important bellwethers of the evolutionary processes that cause biotic transitions. Despite the enormous progress in the measurement and interpretation of Phanerozoic diversity over the past quarter century, much of which has been reported inPaleobiology, these studies have collectively generated at least as many new questions as they have answered—arguably the mark of an area of inquiry that continues to be vital. In this essay, I discuss several outstanding issues in the investigation of Phanerozoic diversity, ranging from the viability of literature-derived databases for investigating global diversity trends, to the biological significance of the myriad biotic transitions that have taken place throughout the Phanerozoic.

Turbidity, arthropods and the evolution of perception:toward a new paradigm of marine phanerozoic diversity

Geological, paleo-oceanographic and paleoclimatological studies have independently demonstrated that the volume of preserved marine sediments, eustatic sea level, the depth to which the sea was oxygenated, the concentration of atmospheric oxygen and carbon dioxide and the amount of terrestrial rainfall fluctuated in a 400 million yr cycle over Phanerozoic time. These data are used to develop the hypothesis that the level of oceanic turbidity co-varied with these changes and that turbidity was the motor, plate tectonics the tempo and perception the mode of evolution in Phanerozoic seas. This hypothesis predicts that during turbidity maxima (Silurian-Devonian, Jurassic-Tertiary), animals with non-visual foraging and predator-avoidance mechanisms and adaptations to marine pelagic, freshwater and terrestrial habits should diversify. During turbidity minima (late-Precambrian-Cambrian, late-Carboniferous-Triassic), animals with visual sensory modalities and benthic habitat specializations should diversify. At the boundary of these environmental conditions, alternating mass extinctions of these adaptive characters and the taxa possessing them should occur. Patterns in the evolution of perceptual modalities, foraging strategies, predator avoidance mechanisms, habitat specializations and inferred aspects of behavioral ecology of aquatic arthropods, i.e. adaptive characters that are less sensitive to instantaneous changes in diversity than are the taxa that carried them, are used to test these predictions. Trilobite diversification and extinction; the adaptive radiation of ostracods and eumalacostracan crustaceans; the iterative evolution of small, fast-moving entomostracan crustaceans; and the evolution of terrestrial chelicerates and decapod crustaceans are all consistent with these predictions. In short, the history of aquatic evolution in Phanerozoic seas can be told in the evolution of perception. Data as disparate as the diversification and extinction of marine plants, cephalopod mollusks and fish are also consistent with predictions deduced from this hypothesis.

Biotic transitions in global marine diversity.

Long-term transitions in the composition of Earth's marine biota during the Phanerozoic have historically been explained in two different ways. One view is that they were mediated through biotic interactions among organisms played out over geologic time. The other is that mass extinctions transcended any such interactions and governed diversity over the long term by resetting the relative diversities of higher taxa. However, a growing body of evidence suggests that macroevolutionary processes effecting biotic transitions during background times were not fundamentally different from those operating during mass extinctions. Physical perturbations at many geographic scales combined to produce the long-term trajectory of Phanerozoic diversity.

Species-Area Relations and Non-Equilibrium Model of Phanerozoic Diversity

Species-Area Relations and Non-Equilibrium Model of Phanerozoic Diversity

Calibrating the Ordovician Radiation of marine life: implications for Phanerozoic diversity trends

It has long been suspected that trends in global marine biodiversity calibrated for the Phanerozoic may be affected by sampling problems. However, this possibility has not been evaluated definitively, and raw diversity trends are generally accepted at face value in macroevolutionary investigations. Here, we analyze a global-scale sample of fossil occurrences that allows us to determine directly the effects of sample size on the calibration of what is generally thought to be among the most significant global biodiversity increases in the history of life: the Ordovician Radiation. Utilizing a composite database that includes trilobites, brachiopods, and three classes of molluscs, we conduct rarefaction analyses to demonstrate that the diversification trajectory for the Radiation was considerably different than suggested by raw diversity time-series. Our analyses suggest that a substantial portion of the increase recognized in raw diversity depictions for the last three Ordovician epochs (the Llandeilian, Caradocian, and Ashgillian) is a consequence of increased sample size of the preserved and catalogued fossil record. We also use biometric data for a global sample of Ordovician trilobites, along with methods of measuring morphological diversity that are not biased by sample size, to show that morphological diversification in this major clade had leveled off by the Llanvirnian. The discordance between raw diversity depictions and more robust taxonomic and morphological diversity metrics suggests that sampling effects may strongly influence our perception of biodiversity trends throughout the Phanerozoic.

Historical evolutionary information in the traditional Linnean hierarchy

The first two ranks above the species level in the traditional Linnean hierarchy — the genus and family — are species based: genera have been erected to unify groups of morphologically similar, closely related species and families have been erected to group genera recognized as closely related because of the shared morphologic characteristics of their species. Diversity patterns of traditional genera and families thus appear congruent with those of species in (a) the Recent (e. g., latitudinal gradients in many groups), (b) compilations of all marine taxa for the entire Phanerozoic (including the stage level), (c) comparisons through time within individual taxa (e. g., Foraminifera, Rugosa, Conodonta), and (d) simulation studies. Genera and families often have a more robust fossil record of diversity than species, especially for poorly sampled groups (e. g., echinoids), because of the range-through record of these polytypic taxa. Simulation studies indicate that paraphyly among traditionally defined taxa is not a fatal problem for diversity studies; in fact, when degradation of the quality of the fossil record is modelled, both diversity and rates of origination and extinction are better represented by including paraphyletic taxa than by restricting data to monophyletic clades. This result underscores the utility of traditional rank-based analyses of the history of diversity.In contrast, the three higher ranks of the Linnean hierarchy — orders, classes and phyla — are defined and recognized by key character complexes assumed to be rooted deep in the developmental program and, therefore, considered to be of special significance. These taxa are unified on the basis of body plan and function, not species morphology. Even if paraphyletic, recognition of such taxa is useful because they represent different functional complexes that reflect biological organization and major evolutionary innovations, often with different ecological capacities. Phanerozoic diversity patterns of orders, classes and phyla are not congruent with those of lower taxa; the higher groups each increased rapidly in the early Paleozoic, during the explosive diversification of body plans in the Cambrian, and then remained stable or declined slightly after the Ordovician. The diversity history of orders superficially resembles that of lower taxa, but this is a result only of ordinal turnover among the Echinodermata coupled with ordinal radiation in the Chordata; it is not a highly damped signal derived from the diversity of species, genera, or families. Despite the stability of numbers among post-Ordovician Linnean higher taxa, the diversity of lower taxa within many of these Bauplan groups fluctuated widely, and these diversity patterns signal embedded ecologic information, such as differences in flexibility in filling or utilizing ecospace.Phylogenetic analysis is vital for understanding the origins and genealogical structure of higher taxa. Only in such fashion can convergence and its implications for ecological constraints and/or opportunities be understood. But blind insistence on the use of monophyletic classifications in all studies would obscure some of the important information contained in traditional taxonomic groupings. The developmental modifications that characterize Linnean higher taxa (and traditionally separate them from their paraphyletic ancestral taxa) provide keys to understanding the role of shifting ecology in macroevolutionary success.