Phanerozoic trends in brachiopod body size from synoptic data

Paleobiology ◽  
2015 ◽  
Vol 41 (3) ◽  
pp. 491-501 ◽  
Author(s):  
Zixiang Zhang ◽  
Michael Augustin ◽  
Jonathan L. Payne
Keyword(s):  
Body Size ◽  
Model Comparison ◽  
Size Increase ◽  
Data Sets ◽  
Size Change ◽  
Invertebrate Paleontology ◽  
History Of ◽  
Global Coverage ◽  
Stratigraphic Ranges ◽  
Permian Mass Extinction

AbstractBody size is one of the most studied phenotypic attributes because it is biologically important and easily measured. Despite a long history of study, however, the pattern of body-size change in diverse higher taxa over the Phanerozoic remains largely unknown because few relevant data sets span more than a single geological period or provide comprehensive, global coverage. In this study, we measured representative specimens of 3414 brachiopod genera illustrated in the Treatise on Invertebrate Paleontology. We applied these size data to stage-resolved stratigraphic ranges from the Treatise and the Paleobiology Database to develop a Phanerozoic record of trends in brachiopod size. Using a model comparison approach, we find that temporal variation in brachiopod size exhibits two distinct modes—a Paleozoic mode of size increase and a post-Paleozoic mode indistinguishable from a random walk. This transition reflects a change in the identities of the most diverse brachiopod orders rather than a shift in mode within any given order. Paleozoic size increase reflects a small, persistent bias toward the origination of new genera larger than those surviving from the previous stage and is identifiable as a statistically supported trend in three orders representing both Class Strophomenata (Order Productida) and Class Rhynchonellata (orders Atrypida and Spiriferida). Extinction exhibits no consistent bias with respect to size. The shift in evolutionary mode across the end-Permian mass extinction adds to long-standing evidence from studies of diversity and abundance that this biotic catastrophe suddenly and permanently altered the evolutionary history of what was, until that time, the most diverse animal phylum on Earth.

Notes on the rates and patterns of size change in evolution

Paleobiology ◽  
1978 ◽  
Vol 4 (3) ◽  
pp. 252-260 ◽  
Author(s):  
Itaru Hayami
Keyword(s):  
Body Size ◽  
Selection Pressure ◽  
Decay Curve ◽  
Selective Advantage ◽  
Size Increase ◽  
Size Change ◽  
Sigmoidal Curve ◽  
Ceratopsian Dinosaurs ◽  
Conventional Unit ◽  
Average Body

The rates and patterns of phyletic body size increase and decrease are discussed on the assumption that size change proceeds toward some limit due to selective advantage. Because the selection pressure must decrease as the average body size of an evolving population approaches the limit, some sigmoidal curve should be regarded as more appropriate for the model of size increase than an exponential curve as in the case of population growth. For phyletic size decrease, the predicted pattern is similar to a radiometric decay curve. The conventional unit of morphological rate, darwin, has been used on the assumption that the change is exponential, but actual lineages in the fossil record may represent only fractions of such sigmoidal curves. Some actual data on size increases in ceratopsian dinosaurs and Jurassic bivalves are examined, and it is concluded that sigmoidal size increase seems also empirically to be a more widespread pattern than exponential.

scholarly journals Crinoids from Svalbard in the aftermath of the end−Permian mass extinction

2015 ◽  
Vol 36 (3) ◽  
pp. 225-238 ◽  
Author(s):  
Mariusz A. Salamon ◽  
Przemysław Gorzelak ◽  
Nils−Martin Hanken ◽  
Henrik Erevik Riise ◽  
Bruno Ferré
Keyword(s):  
Mass Extinction ◽  
Lower Triassic ◽  
Late Paleozoic ◽  
Early Triassic ◽  
Major Event ◽  
Early Mesozoic ◽  
History Of ◽  
Permian Extinction ◽  
Stratigraphic Ranges ◽  
Permian Mass Extinction

AbstractThe end-Permian mass extinction constituted a major event in the history of crinoids. It led to the demise of the major Paleozoic crinoid groups including cladids, disparids, flexibles and camerates. It is widely accepted that a single lineage, derived from a late Paleozoic cladid ancestor (Ampelocrinidae), survived this mass extinction. Holocrinid crinoids (Holocrinus, Holocrinida) along with recently described genus Baudicrinus (Encrinida), the only crinoid groups known from the Early Triassic, are considered the stem groups for the post-Paleozoic monophyletic subclass Articulata. Here, we report preliminary data on unexpectedly diverse crinoid faunas comprising at least four orders from the Lower Triassic (Induan and Olenekian) of Svalbard, extending their stratigraphic ranges deeper into the early Mesozoic. These findings strongly imply that the recovery of crinoids in the aftermath of the end-Permian extinction began much earlier at higher palaeolatitudes than in the central Tethys.

HOLOCENE LAND SNAIL BODY SIZE CHANGE IN ALGERIA, NW AFRICA, AND ITS POSSIBLE CAUSES

2017 ◽  
Author(s):  
Nora Soto ◽  
◽  
Yurena Yanes ◽  
David Lubell
Keyword(s):  
Body Size ◽  
Land Snail ◽  
Size Change

Empirical Methods in Short-Term Climate Prediction

2006 ◽  
Author(s):  
Huug van den Dool
Keyword(s):  
Climate Prediction ◽  
Empirical Orthogonal Functions ◽  
Data Sets ◽  
Seasonal Forecasts ◽  
Short Term ◽  
Orthogonal Functions ◽  
Ocean Atmosphere Interaction ◽  
Global Coverage ◽  
Atmosphere Interaction ◽  
Global Data

This clear and accessible text describes the methods underlying short-term climate prediction at time scales of 2 weeks to a year. Although a difficult range to forecast accurately, there have been several important advances in the last ten years, most notably in understanding ocean-atmosphere interaction (El Nino for example), the release of global coverage data sets, and in prediction methods themselves. With an emphasis on the empirical approach, the text covers in detail empirical wave propagation, teleconnections, empirical orthogonal functions, and constructed analogue. It also provides a detailed description of nearly all methods used operationally in long-lead seasonal forecasts, with new examples and illustrations. The challenges of making a real time forecast are discussed, including protocol, format, and perceptions about users. Based where possible on global data sets, illustrations are not limited to the Northern Hemisphere, but include several examples from the Southern Hemisphere.

Northern Hemisphere Glaciation, African Climate and Evolution

2021 ◽  
Author(s):  
Martin H. Trauth ◽  
Asfawossen Asrat ◽  
Nadine Berner ◽  
Faysal Bibi ◽  
Verena Foerster ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Species Turnover ◽  
Abrupt Onset ◽  
Data Sets ◽  
Scientific Idea ◽  
Gradual Process ◽  
Before And After ◽  
History Of ◽  
Change Point Models ◽  
Original Interpretation

<p>The hypothesis of a connection between the onset (or intensification) of Northern Hemisphere Glaciation (NHG), the stepwise increase in African aridity (and climate variability) and an important mammalian (including hominin) species turnover is a textbook example of the initiation of a scientific idea and its propagation in science. It is, however, also an example of the persistent popularity of a hypothesis despite mounting evidence against it. The first part of our work analyzes of the history of the scientific idea by seeking its roots, including coincidental meetings and exchanges between of scientists, at project meetings, conferences and workshops. The consequences of this idea are examined and its influence on subsequent scientific investigations both before and after it has been falsified. In the second part of our investigation, we examine why the idea that the high latitudes have a major control on the climate of the low latitudes and thus early human evolution persists. For this purpose, an attempt is made to understand the original interpretation of the data, with special consideration of the composition of the scientific team and their scientific backgrounds and persuasions. Some of the key records in support of the hypothesis of a step-wise transition will be statistically re-analyzed by fitting change-point models to the time series to determine the midpoint and duration of the transition – in case such a transition is found in the data. A critical review of key publications in support of such a connection and a statistical re-analysis of key data sets leads to three conclusions: (1) Northern Hemisphere Glaciation is a gradual process between ~3.5–2.5 Ma, not an abrupt onset, either at ~2.5 Ma, nor at ~2.8 Ma, or any other time in the Late Cenozoic Era, (2) the trend towards greater aridity in Africa during this period was also gradual, not stepwise in the sense of a consistent transition of a duration of ≤0.2 Ma, and (3) accordingly, a step-wise change in environmental conditions cannot be used to explain an important mammalian (including hominin) species turnover.</p>

scholarly journals The seven sisters DANCe

2018 ◽  
Vol 612 ◽  
pp. A70 ◽  
Author(s):  
J. Olivares ◽  
E. Moraux ◽  
L. M. Sarro ◽  
H. Bouy ◽  
A. Berihuete ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Model Comparison ◽  
Precise Determination ◽  
Model Parameters ◽  
Data Sets ◽  
Adequate Model ◽  
Comparison Results ◽  
Bayesian Evidence ◽  
Mass Segregation

Context. Membership analyses of the DANCe and Tycho + DANCe data sets provide the largest and least contaminated sample of Pleiades candidate members to date. Aims. We aim at reassessing the different proposals for the number surface density of the Pleiades in the light of the new and most complete list of candidate members, and inferring the parameters of the most adequate model. Methods. We compute the Bayesian evidence and Bayes Factors for variations of the classical radial models. These include elliptical symmetry, and luminosity segregation. As a by-product of the model comparison, we obtain posterior distributions for each set of model parameters. Results. We find that the model comparison results depend on the spatial extent of the region used for the analysis. For a circle of 11.5 parsecs around the cluster centre (the most homogeneous and complete region), we find no compelling reason to abandon King’s model, although the Generalised King model introduced here has slightly better fitting properties. Furthermore, we find strong evidence against radially symmetric models when compared to the elliptic extensions. Finally, we find that including mass segregation in the form of luminosity segregation in the J band is strongly supported in all our models. Conclusions. We have put the question of the projected spatial distribution of the Pleiades cluster on a solid probabilistic framework, and inferred its properties using the most exhaustive and least contaminated list of Pleiades candidate members available to date. Our results suggest however that this sample may still lack about 20% of the expected number of cluster members. Therefore, this study should be revised when the completeness and homogeneity of the data can be extended beyond the 11.5 parsecs limit. Such a study will allow for more precise determination of the Pleiades spatial distribution, its tidal radius, ellipticity, number of objects and total mass.

scholarly journals Examination of Different Item Response Theory Models on Tests Composed of Testlets

2017 ◽  
Vol 6 (4) ◽  
pp. 113
Author(s):  
Esin Yilmaz Kogar ◽  
Hülya Kelecioglu
Keyword(s):  
Item Response Theory ◽  
Sample Size ◽  
Item Response ◽  
Data Sets ◽  
Meaningful Difference ◽  
Response Theory ◽  
Size Change ◽  
Data Set ◽  
Testlet Response Theory ◽  
Item Response Theory Models

The purpose of this research is to first estimate the item and ability parameters and the standard error values related to those parameters obtained from Unidimensional Item Response Theory (UIRT), bifactor (BIF) and Testlet Response Theory models (TRT) in the tests including testlets, when the number of testlets, number of independent items, and sample size change, and then to compare the obtained results. Mathematic test in PISA 2012 was employed as the data collection tool, and 36 items were used to constitute six different data sets containing different numbers of testlets and independent items. Subsequently, from these constituted data sets, three different sample sizes of 250, 500 and 1000 persons were selected randomly. When the findings of the research were examined, it was determined that, generally the lowest mean error values were those obtained from UIRT, and TRT yielded a mean of error estimation lower than that of BIF. It was found that, under all conditions, models which take into consideration the local dependency have provided a better model-data compatibility than UIRT, generally there is no meaningful difference between BIF and TRT, and both models can be used for those data sets. It can be said that when there is a meaningful difference between those two models, generally BIF yields a better result. In addition, it has been determined that, in each sample size and data set, item and ability parameters and correlations of errors of the parameters are generally high.

Carboniferous-Triassic gastropod diversity patterns and the Permo-Triassic mass extinction

Paleobiology ◽  
1990 ◽  
Vol 16 (2) ◽  
pp. 187-203 ◽  
Author(s):  
Douglas H. Erwin
Keyword(s):  
Mass Extinction ◽  
Detrended Correspondence Analysis ◽  
Taxonomic Composition ◽  
Late Paleozoic ◽  
Lower Permian ◽  
Two Phase ◽  
Environmental Distribution ◽  
Extinction Rates ◽  
History Of ◽  
Permian Mass Extinction

Paleozoic and post-Paleozoic marine faunas are strikingly different in composition. Paleozoic marine gastropods may be divided into archaic and modern groups based on taxonomic composition, ecological role, and morphology. Paleozoic assemblages were dominated by pleurotomariids (Eotomariidae and Phymatopleuridae), the Pseudozygopleuridae, and, to a lesser extent, the Euomphalidae, while Triassic assemblages were dominated by the Trochiina, Amberleyacea, and new groups of Loxonematoidea and Pleurotomariina. Several new groups of caenogastropods appeared as well. Yet the importance of the end-Permian mass extinction in generating these changes has been questioned. As part of a study of the diversity history of upper Paleozoic and Triassic gastropods, to test the extent to which taxonomic and morphologic trends established in the late Paleozoic are continued after the extinction, and to determine the patterns of selectivity operating during the extinction, I assembled generic and morphologic diversity data for 396 genera in 75 families from the Famennian through the Norian stages. Within this interval, gastropod genera underwent an adaptive radiation during the Visean and Namurian, largely of pleurotomariids, a subsequent period of dynamic stability through the Leonardian, a broad-based decline during the end-Permian mass extinction, and a two-phase post-extinction rebound during the Triassic. The patterns of generic diversity within superfamily-level clades were analyzed using Q-mode factor analysis and detrended correspondence analysis.The results demonstrate that taxonomic affinity, previous clade history, generic age, and gross morphology did not determine survival probability of genera during the end-Permian extinction, with the exception of the bellerophontids, nor did increasing diversity within clades or expansion of particular morphologies prior to the extinction facilitate survival during the extinction or success after it. The pleurotomariids diversified during the Lower Permian, but were heavily hit by the extinction. Similarly, trochiform and turriculate morphologies, among those which Vermeij (1987) has identified as having increased predation resistance, were expanding in the late Paleozoic, but suffered similar extinction rates to other nondiversifying clades. Survival was a consequence of broad geographic and environmental distribution, as was the case during background periods.

scholarly journals New data towards the development of a comprehensive taphonomic framework for the Late Jurassic Cleveland-Lloyd Dinosaur Quarry, Central Utah

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3368 ◽  
Author(s):  
Joseph E. Peterson ◽  
Jonathan P. Warnock ◽  
Shawn L. Eberhart ◽  
Steven R. Clawson ◽  
Christopher R. Noto
Keyword(s):  
Late Jurassic ◽  
Data Sets ◽  
Morrison Formation ◽  
Multiple Sources ◽  
Theropod Dinosaurs ◽  
The Matrix ◽  
Significant Step ◽  
Primary Driver ◽  
History Of ◽  
Bone Fragments

The Cleveland-Lloyd Dinosaur Quarry (CLDQ) is the densest deposit of Jurassic theropod dinosaurs discovered to date. Unlike typical Jurassic bone deposits, it is dominated by the presence ofAllosaurus fragilis. Since excavation began in the 1920s, numerous hypotheses have been put forward to explain the taphonomy of CLDQ, including a predator trap, a drought assemblage, and a poison spring. In an effort to reconcile the various interpretations of the quarry and reach a consensus on the depositional history of CLDQ, new data is required to develop a robust taphonomic framework congruent with all available data. Here we present two new data sets that aid in the development of such a robust taphonomic framework for CLDQ. First, x-ray fluorescence of CLDQ sediments indicate elevated barite and sulfide minerals relative to other sediments from the Morrison Formation in the region, suggesting an ephemeral environment dominated by periods of hypereutrophic conditions during bone accumulation. Second, the degree of abrasion and hydraulic equivalency of small bone fragments dispersed throughout the matrix were analyzed from CLDQ. Results of these analyses suggest that bone fragments are autochthonous or parautochthonous and are derived from bones deposited in the assemblage rather than transported. The variability in abrasion exhibited by the fragments is most parsimoniously explained by local periodic re-working and re-deposition during seasonal fluctuations throughout the duration of the quarry assemblage. Collectively, these data support previous interpretations that the CLDQ represents an attritional assemblage in a poorly-drained overbank deposit where vertebrate remains were introduced post-mortem to an ephemeral pond during flood conditions. Furthermore, while the elevated heavy metals detected at the Cleveland-Lloyd Dinosaur Quarry are not likely the primary driver for the accumulation of carcasses, they are likely the result of multiple sources; some metals may be derived from post-depositional and diagenetic processes, and others are potentially produced from an abundance of decomposing vertebrate carcasses. These new data help to support the inferred depositional environment of the quarry as an ephemeral pond, and represent a significant step in understanding the taphonomy of the bonebed and Late Jurassic paleoecology in this region.

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