Diversification Declines in Major Dinosaurian Clades are not Because of Edge Effects or Incomplete Fossil Sampling

Mapping Intimacies ◽

10.21203/rs.3.rs-907951/v1 ◽

2021 ◽

Author(s):

Manabu Sakamoto ◽

Michael Benton ◽

Chris Venditti

Keyword(s):

Edge Effect ◽

Mass Extinction ◽

Taxonomic Diversity ◽

Mass Extinctions ◽

Model Framework ◽

Extinction Event ◽

Under Sampling ◽

Phylogenetic Model ◽

Mass Extinction Event

Abstract Signatures of catastrophic mass extinctions have long been reported to be obscured by the edge effect where taxonomic diversity appears to decline gradually. Similarly, models of diversification based on splitting of branches on a phylogenetic tree might also be affected by undersampling of divergences towards the edge. The implication is that long-term declines in diversification recovered from such models – e.g., in dinosaurs – may be artefacts of unsampled divergences. However, this effect has never been explicitly tested in a phylogenetic model framework – i.e., whether phylogenetic nodes (speciation events) close to the edge are under-sampled and if diversification declines are artefacts of such under-sampling. Here, we test whether dinosaur species in temporal proximity to the Cretaceous-Paleogene mass extinction event are associated with fewer nodes than expected, and whether this under-sampling can account for the diversification decline. We find on the contrary that edge taxa have higher numbers of nodes than expected and that accounting for this offset does not affect the diversification decline. We demonstrate that the observed diversification declines in the three major dinosaurian clades in the Late Cretaceous are not artefacts of the edge effect.

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Dead clades walking are a pervasive macroevolutionary pattern

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2019208118 ◽

2021 ◽

Vol 118 (15) ◽

pp. e2019208118

Author(s):

B. Davis Barnes ◽

Judith A. Sclafani ◽

Andrew Zaffos

Keyword(s):

Mass Extinction ◽

Bayesian Method ◽

Marine Invertebrate ◽

Mass Extinctions ◽

Extinction Event ◽

Genus Richness ◽

Mass Extinction Event ◽

Extinction Events ◽

Mass Extinction Events

D. Jablonski [Proc. Natl. Acad. Sci. U.S.A. 99, 8139–8144 (2002)] coined the term “dead clades walking” (DCWs) to describe marine fossil orders that experience significant drops in genus richness during mass extinction events and never rediversify to previous levels. This phenomenon is generally interpreted as further evidence that the macroevolutionary consequences of mass extinctions can continue well past the formal boundary. It is unclear, however, exactly how long DCWs are expected to persist after extinction events and to what degree they impact broader trends in Phanerozoic biodiversity. Here we analyze the fossil occurrences of 134 skeletonized marine invertebrate orders in the Paleobiology Database (paleobiodb.org) using a Bayesian method to identify significant change points in genus richness. Our analysis identifies 70 orders that experience major diversity losses without recovery. Most of these taxa, however, do not fit the popular conception of DCWs as clades that narrowly survive a mass extinction event and linger for only a few stages before succumbing to extinction. The median postdrop duration of these DCW orders is long (>30 Myr), suggesting that previous studies may have underestimated the long-term taxonomic impact of mass extinction events. More importantly, many drops in diversity without recovery are not associated with mass extinction events and occur during background extinction stages. The prevalence of DCW orders throughout both mass and background extinction intervals and across phyla (>50% of all marine invertebrate orders) suggests that the DCW pattern is a major component of macroevolutionary turnover.

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Dinosaurs in decline tens of millions of years before their final extinction

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1521478113 ◽

2016 ◽

Vol 113 (18) ◽

pp. 5036-5040 ◽

Cited By ~ 38

Author(s):

Manabu Sakamoto ◽

Michael J. Benton ◽

Chris Venditti

Keyword(s):

Mass Extinction ◽

Marked Reduction ◽

Evolutionary Dynamics ◽

General Pattern ◽

Extinction Rate ◽

Catastrophic Event ◽

Extinction Event ◽

Mass Extinction Event ◽

First Time

Whether dinosaurs were in a long-term decline or whether they were reigning strong right up to their final disappearance at the Cretaceous–Paleogene (K-Pg) mass extinction event 66 Mya has been debated for decades with no clear resolution. The dispute has continued unresolved because of a lack of statistical rigor and appropriate evolutionary framework. Here, for the first time to our knowledge, we apply a Bayesian phylogenetic approach to model the evolutionary dynamics of speciation and extinction through time in Mesozoic dinosaurs, properly taking account of previously ignored statistical violations. We find overwhelming support for a long-term decline across all dinosaurs and within all three dinosaurian subclades (Ornithischia, Sauropodomorpha, and Theropoda), where speciation rate slowed down through time and was ultimately exceeded by extinction rate tens of millions of years before the K-Pg boundary. The only exceptions to this general pattern are the morphologically specialized herbivores, the Hadrosauriformes and Ceratopsidae, which show rapid species proliferations throughout the Late Cretaceous instead. Our results highlight that, despite some heterogeneity in speciation dynamics, dinosaurs showed a marked reduction in their ability to replace extinct species with new ones, making them vulnerable to extinction and unable to respond quickly to and recover from the final catastrophic event.

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Could a potential Anthropocene mass extinction define a new geological period?

The Anthropocene Review ◽

10.1177/2053019616666867 ◽

2016 ◽

Vol 3 (3) ◽

pp. 208-217 ◽

Cited By ~ 3

Author(s):

Karen L Bacon ◽

Graeme T Swindles

Keyword(s):

Mass Extinction ◽

Global Temperature ◽

Current Debate ◽

Mass Extinctions ◽

Biodiversity Crisis ◽

Extinction Event ◽

Geological Boundaries ◽

Near Term ◽

Mass Extinction Event ◽

Geological Period

A key aspect of the current debate about the Anthropocene focuses on defining a new geological epoch. Features of the Anthropocene include a biodiversity crisis with the potential to reach ‘mass extinction’ status alongside increasing global CO2 and temperature. Previous geological boundaries associated with mass extinctions, rises in atmospheric CO2 and rises in global temperature are more usually associated with transitions between geological periods. The current rapid increase in species extinctions suggest that a new mass extinction event is most likely imminent in the near-term future. Although CO2 levels are currently low in comparison with the rest of the Phanerozoic, they are rising rapidly along with global temperatures. This suggests that defining the Anthropocene as a new geological period, rather than a new epoch, may be more consistent with previous geological boundaries in the Phanerozoic.

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Evolution and dispersal of snakes across the Cretaceous-Paleogene mass extinction

Nature Communications ◽

10.1038/s41467-021-25136-y ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Catherine G. Klein ◽

Davide Pisani ◽

Daniel J. Field ◽

Rebecca Lakin ◽

Matthew A. Wills ◽

...

Keyword(s):

Mass Extinction ◽

Teleost Fishes ◽

Mass Extinctions ◽

Dispersal Patterns ◽

Extinction Event ◽

Living Species ◽

Rapid Diversification ◽

Molecular Dataset ◽

Global Biodiversity ◽

Mass Extinction Event

AbstractMass extinctions have repeatedly shaped global biodiversity. The Cretaceous-Paleogene (K-Pg) mass extinction caused the demise of numerous vertebrate groups, and its aftermath saw the rapid diversification of surviving mammals, birds, frogs, and teleost fishes. However, the effects of the K-Pg extinction on the evolution of snakes—a major clade of predators comprising over 3,700 living species—remains poorly understood. Here, we combine an extensive molecular dataset with phylogenetically and stratigraphically constrained fossil calibrations to infer an evolutionary timescale for Serpentes. We reveal a potential diversification among crown snakes associated with the K-Pg mass extinction, led by the successful colonisation of Asia by the major extant clade Afrophidia. Vertebral morphometrics suggest increasing morphological specialisation among marine snakes through the Paleogene. The dispersal patterns of snakes following the K-Pg underscore the importance of this mass extinction event in shaping Earth’s extant vertebrate faunas.

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The extinction and survival of sharks across the end-Cretaceous mass extinction

10.1101/2021.01.20.427414 ◽

2021 ◽

Author(s):

Mohamad Bazzi ◽

Nicolás E. Campione ◽

Per E. Ahlberg ◽

Henning Blom ◽

Benjamin P. Kear

Keyword(s):

Mass Extinction ◽

Large Scale ◽

Dental Morphology ◽

Mass Extinctions ◽

Morphological Response ◽

Geometric Morphometric ◽

Marine Predators ◽

Extinction Event ◽

Mass Extinction Event ◽

Early Paleogene

AbstractSharks (Selachimorpha) are iconic marine predators that have survived multiple mass extinctions over geologic time. Their fossil record is represented by an abundance of teeth, which traditionally formed the basis for reconstructing large-scale diversity changes among different selachimorph clades. By contrast, corresponding patterns in shark ecology, as measured through morphological disparity, have received comparatively limited analytical attention. Here, we use a geometric morphometric approach to comprehensively examine the dental morphology of multiple shark lineages traversing the catastrophic end-Cretaceous mass extinction — this event terminated the Mesozoic Era 66 million years ago. Our results show that selachimorphs maintained virtually static levels of dental disparity in most of their constituent clades during the Cretaceous/Paleogene transition. Nevertheless, selective extinctions did impact on apex predator lineages characterized by triangular blade-like teeth, and in particular, lamniforms including the dominant Cretaceous anacoracids. Other groups, such as, triakid carcharhiniforms, squalids, and hexanchids, were seemingly unaffected. Finally, while some lamniform lineages experienced morphological depletion, others underwent a post-extinction disparity increase, especially odontaspidids, which are typified by narrow-cusped teeth adapted for feeding on fishes. This disparity shift coincides with the early Paleogene radiation of teleosts, a possible prey source, as well as the geographic relocation of shark disparity ‘hotspots’, perhaps indicating a regionally disjunct pattern of extinction recovery. Ultimately, our study reveals a complex morphological response to the end-Cretaceous mass extinction event, the dynamics of which we are only just beginning to understand.

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Impact of K-Pg Mass Extinction Event on Crocodylomorpha Inferred from Phylogeny of Extinct and Extant Taxa

10.1101/2021.01.14.426715 ◽

2021 ◽

Author(s):

Andrew F. Magee ◽

Sebastian Höhna

Keyword(s):

Mass Extinction ◽

Likelihood Function ◽

Simulated Data ◽

Mass Extinctions ◽

Holistic View ◽

Occurrence Data ◽

Extinction Event ◽

Mass Extinction Event ◽

Biodiversity Changes ◽

The Impact

AbstractCrocodilians and their allies have survived several mass extinction events. However, the impact of the K-Pg mass extinction event on crocodylomorphs is considered as minor or non-existent although other clades of archosaurs, e.g., non-avian dinosaurs and pterosaurs, went extinct completely. Previous approaches using fossil occurrence data alone have proven inconclusive. In this paper, we take a phylogenetic approach using extant and extinct species. The time-calibrated phylogeny of extant crocodilians provides insights into the pattern of recent biodiversity changes whereas fossil occurrence data provide insights about the more ancient past. The two data sources combined into a single phylogeny with extinct and extant taxa provide a holistic view of the historical biodiversity. To utilize this combined data and to infer the impact of the K-Pg mass extinction event, we derive the likelihood function for a time-varying (episodic) serially sampled birth-death model that additionally incorporates mass extinctions and bursts of births. We implemented the likelihood function in a Bayesian framework with recently developed smoothing priors to accommodate for both abrupt and gradual changes in speciation, extinction and fossilization rates. Contrary to previous research, we find strong evidence for the K-Pg extinction event in crocodiles and their allies. This signal is robust to uncertainty in the phylogeny and the prior on the mass extinctions. Through simulated data analyses, we show that there is high power to detect this mass extinction and little risk of false positives.

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Are Insects Heading Toward Their First Mass Extinction? Distinguishing Turnover From Crises in Their Fossil Record

Annals of the Entomological Society of America ◽

10.1093/aesa/saaa042 ◽

2020 ◽

Author(s):

Sandra R Schachat ◽

Conrad C Labandeira

Keyword(s):

Mass Extinction ◽

Fossil Record ◽

Taxonomic Diversity ◽

Insect Diversity ◽

Mass Extinctions ◽

Sudden Loss ◽

Faunal Turnover ◽

Sixth Mass Extinction ◽

Extinction Event ◽

Permian Extinction

Abstract Time and again, over hundreds of millions of years, environmental disturbances have caused mass extinctions of animals ranging from reptiles to corals. The anthropogenic loss of species diversity happening now is often discussed as the ‘sixth mass extinction’ in light of the ‘Big Five’ mass extinctions in the fossil record. But insects, whose taxonomic diversity now appears to be threatened by human activity, have a unique extinction history. Prehistoric losses of insect diversity at the levels of order and family appear to have been driven by competition among insect lineages, with biotic replacement ensuring minimal net losses in taxonomic diversity. The end-Permian extinction, the ‘mother of mass extinctions’ in the seas, was more of a faunal turnover than a mass extinction for insects. Insects’ current biotic crisis has been measured in terms of the loss of abundance and biomass (rather than the loss of species, genera, or families) and these are essentially impossible to measure in the fossil record. However, should the ongoing loss of insect abundance and biomass cause the demise of many insect families, the current extinction event may well be the first sudden loss of higher-level insect diversity in our planet’s history. This is not insects’ sixth mass extinction—in fact, it may become their first.

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DINOSAURS STILL IN LONG-TERM NET SPECIATION DECLINE BEFORE THE K-PG BOUNDARY

10.31233/osf.io/zwg2j ◽

2019 ◽

Author(s):

Manabu Sakamoto ◽

Michael J Benton ◽

Chris Venditti

Keyword(s):

Taxonomic Diversity ◽

Suitable Habitat ◽

Climate Data ◽

Niche Modelling ◽

Model Framework ◽

Time Intervals ◽

Number Of Species ◽

Dynamic Relationship ◽

Mass Extinction Event

A recent study in Nature Communications used ecological niche modelling (ENM) to project suitable habitat for dinosaurs during the latest stages of the Cretaceous Period (83-66 million years [Myr] ago) from detailed climate data, apparently refuting the hypothesis that dinosaurs were in a long-term decline before the Cretaceous-Paleogene (K-Pg) mass extinction event. However, we note here that: 1) suitable habitat does not necessarily equate to taxonomic diversity (i.e., number of species); and 2) lack of a decline in diversity across time intervals is not evidence against a gradual decline in net speciation through time – diversity and net speciation measure two separate things. Diversity measures the number of species within discrete time intervals, while phylogenetically inferred net speciation measures the dynamic relationship between speciation and extinction through time. Additionally, net speciation is estimated in a model framework that accounts for statistically undesired effects of shared ancestry, whereas diversity is not. Thus, diversity and net speciation are not directly comparable, and a lack of a decline in diversity does not necessarily refute a decline in net speciation through time.

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