scholarly journals Multifaceted disparity approach reveals dinosaur herbivory flourished before the end-Cretaceous mass extinction

Paleobiology ◽  
2018 ◽  
Vol 44 (4) ◽  
pp. 620-637 ◽  
Author(s):  
Klara K. Nordén ◽  
Thomas L. Stubbs ◽  
Albert Prieto-Márquez ◽  
Michael J. Benton
Keyword(s):  
Early Cretaceous ◽  
Mass Extinction ◽  
Morphological Evolution ◽  
Temporal Patterns ◽  
Taxonomic Diversity ◽  
Ecological Diversity ◽  
Morphological Disparity ◽  
Rapid Extinction

AbstractUnderstanding temporal patterns in biodiversity is an enduring question in paleontology. Compared with studies of taxonomic diversity, long-term perspectives on ecological diversity are rare, particularly in terrestrial systems. Yet ecological diversity is critical for the maintenance of biodiversity, especially during times of major perturbations. Here, we explore the ecological diversity of Cretaceous herbivorous dinosaurs leading up to the K-Pg extinction, using dental and jaw morphological disparity as a proxy. We test the hypothesis that a decline in ecological diversity could have facilitated their rapid extinction 66 Ma. We apply three disparity metrics that together capture different aspects of morphospace occupation and show how this approach is key to understanding patterns of morphological evolution. We find no evidence of declining disparity in herbivorous dinosaurs as a whole—suggesting that dinosaur ecological diversity remained high during the last 10 Myr of their existence. Clades show different disparity trends through the Cretaceous, but none except sauropods exhibits a long-term decline. Herbivorous dinosaurs show two disparity peaks characterized by different processes; in the Early Cretaceous by expansion in morphospace and in the Campanian by morphospace packing. These trends were only revealed by using a combination of disparity metrics, demonstrating how this approach can offer novel insights into macroevolutionary processes underlying patterns of disparity and ecological diversity.

scholarly journals Decoupling of morphological disparity and taxonomic diversity during the end-Permian mass extinction

Paleobiology ◽  
2021 ◽  
pp. 1-16
Author(s):  
Junyu Wan ◽  
William J. Foster ◽  
Li Tian ◽  
Thomas L. Stubbs ◽  
Michael J. Benton ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Microbial Mats ◽  
Benthic Communities ◽  
Ecological Impact ◽  
Taxonomic Diversity ◽  
Morphological Disparity ◽  
Extinction Event ◽  
Permian Extinction ◽  
Permian Mass Extinction ◽  
Marine Platform

Abstract An increasing number of unexpectedly diverse benthic communities are being reported from microbially precipitated carbonate facies in shallow-marine platform settings after the end-Permian mass extinction. Ostracoda, which was one of the most diverse and abundant metazoan groups during this interval, recorded its greatest diversity and abundance associated with these facies. Previous studies, however, focused mainly on taxonomic diversity and, therefore, left room for discussion of paleoecological significance. Here, we apply a morphometric method (semilandmarks) to investigate morphological variance through time to better understand the ecological consequences of the end-Permian mass extinction and to examine the hypothesis that microbial mats played a key role in ostracod survival. Our results show that taxonomic diversity and morphological disparity were decoupled during the end-Permian extinction and that morphological disparity declined rapidly at the onset of the end-Permian extinction, even though the high diversity of ostracods initially survived in some places. The decoupled changes in taxonomic diversity and morphological disparity suggest that the latter is a more robust proxy for understanding the ecological impact of the extinction event, and the low morphological disparity of ostracod faunas is a consequence of sustained environmental stress or a delayed post-Permian radiation. Furthermore, the similar morphological disparity of ostracods between microbialite and non-microbialite facies indicates that microbial mats most likely represent a taphonomic window rather than a biological refuge during the end-Permian extinction interval.

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

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.

Comparing the differential filling of morphospace and allometric space through time: the morphological and developmental dynamics of Early Jurassic ammonoids

Paleobiology ◽  
2011 ◽  
Vol 37 (3) ◽  
pp. 369-382 ◽  
Author(s):  
Sylvain Gerber
Keyword(s):  
Evolutionary Dynamics ◽  
Morphological Evolution ◽  
Taxonomic Diversity ◽  
Early Jurassic ◽  
Adult Size ◽  
Morphological Disparity ◽  
History Of ◽  
Developmental Dynamics ◽  
Shell Geometry ◽  
Average Adult

The evolutionary history of shell geometry of Early Jurassic ammonoids during the Pliensbachian–Toarcian second-order mass extinction is explored at both adult and ontogenetic levels. The ontogenetic approach builds on the concept of allometric space to get insights into the developmental aspects of morphological evolution. Investigation of the deployment of taxa in adult morphospace and allometric space allows the appraisal of the temporal evolution of morphological and allometric disparities. Curves of taxonomic diversity, adult morphological disparity, allometric disparity, and average adult size are contrasted. Results show that during the Pliensbachian–Toarcian interval, ammonoids underwent two successive and drastic declines in taxonomic diversity. Patterns of morphospace and allometric space occupancy suggest nonselective extinction at both morphological and developmental levels. Another measure of allometric disparity suggests the occurrence of two heterochronic trends, a peramorphocline followed by a paedomorphocline, during the Toarcian. These trends are concomitant with changes in average adult size that compensate for the heterochronic effects and explain the striking stability of morphological disparity despite changes in diversity. The results also emphasize the existence of two contrasted evolutionary dynamics in Pliensbachian and Toarcian ammonoids. Methodologically, the allometric disparity approach appears to be a fruitful tool to analyze the rather understudied clade-wide ontogenetic aspects of morphological evolution. Combining multiple approaches to describe clade morphological dynamics leads to a better characterization and understanding of the diversity-disparities relationships and a better distinction of the potential processes driving these macroevolutionary patterns.

scholarly journals Decoupling of morphological disparity and taxonomic diversity during the end-Permian mass extinction – ADDENDUM

Paleobiology ◽  
2021 ◽  
pp. 1-1
Author(s):  
Junyu Wan ◽  
William J. Foster ◽  
Li Tian ◽  
Thomas L. Stubbs ◽  
Michael J. Benton ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Taxonomic Diversity ◽  
Morphological Disparity ◽  
Permian Mass Extinction

scholarly journals Imaging spatio-temporal patterns of long-term potentiation in mouse hippocampus

2003 ◽  
Vol 358 (1432) ◽  
pp. 689-693 ◽  
Author(s):  
Toshiyuki Hosokawa ◽  
Masaki Ohta ◽  
Takeshi Saito ◽  
Alan Fine
Keyword(s):  
Hippocampal Slices ◽  
Temporal Patterns ◽  
Long Term Potentiation ◽  
Optical Recording ◽  
Stratum Radiatum ◽  
High Frequency Stimulation ◽  
Optical Signals ◽  
Term Potentiation ◽  
Spatio Temporal

Spatio-temporal patterns of neuronal activity before and after the induction of long-term potentiation in mouse hippocampal slices were studied using a real-time high-resolution optical recording system. After staining the slices with voltage-sensitive dye, transmitted light images and extracellular field potentials were recorded in response to stimuli applied to CA1 stratum radiatum. Optical and electrical signals in response to single test pulses were enhanced for at least 30 minutes after brief high-frequency stimulation at the same site. In two-pathway experiments, potentiation was restricted to the tetanized pathway. The optical signals demonstrated that both the amplitude and area of the synaptic response were increased, in patterns not predictable from the initial, pretetanus, pattern of activation. Optical signals will be useful for investigating spatio-temporal patterns of synaptic enhancement underlying information storage in the brain.

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

2016 ◽  
Vol 113 (18) ◽  
pp. 5036-5040 ◽  
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.

Mass extinctions alter extinction and origination dynamics with respect to body size

2021 ◽  
Vol 288 (1960) ◽  
Author(s):  
Pedro M. Monarrez ◽  
Noel A. Heim ◽  
Jonathan L. Payne
Keyword(s):  
Body Size ◽  
Mass Extinction ◽  
Evolutionary Biology ◽  
Marine Animal ◽  
Mass Extinctions ◽  
Extinction Selectivity ◽  
Extinction Events ◽  
Mass Extinction Events ◽  
Marine Biosphere

Whether mass extinctions and their associated recoveries represent an intensification of background extinction and origination dynamics versus a separate macroevolutionary regime remains a central debate in evolutionary biology. The previous focus has been on extinction, but origination dynamics may be equally or more important for long-term evolutionary outcomes. The evolution of animal body size is an ideal process to test for differences in macroevolutionary regimes, as body size is easily determined, comparable across distantly related taxa and scales with organismal traits. Here, we test for shifts in selectivity between background intervals and the ‘Big Five’ mass extinction events using capture–mark–recapture models. Our body-size data cover 10 203 fossil marine animal genera spanning 10 Linnaean classes with occurrences ranging from Early Ordovician to Late Pleistocene (485–1 Ma). Most classes exhibit differences in both origination and extinction selectivity between background intervals and mass extinctions, with the direction of selectivity varying among classes and overall exhibiting stronger selectivity during origination after mass extinction than extinction during the mass extinction. Thus, not only do mass extinction events shift the marine biosphere into a new macroevolutionary regime, the dynamics of recovery from mass extinction also appear to play an underappreciated role in shaping the biosphere in their aftermath.

Sign in / Sign up

Export Citation Format

Share Document