scholarly journals Towards a morphological metric of assemblage dynamics in the fossil record: a test case using planktonic foraminifera

2016 ◽  
Vol 371 (1691) ◽  
pp. 20150227 ◽  
Author(s):  
Allison Y. Hsiang ◽  
Leanne E. Elder ◽  
Pincelli M. Hull
Keyword(s):  
Fossil Record ◽  
Phylogenetic Signal ◽  
Planktonic Foraminifera ◽  
Three Dimensional ◽  
Test Case ◽  
Ecological Traits ◽  
The North ◽  
Extant Species ◽  
The Relationship ◽  
Assemblage Size

With a glance, even the novice naturalist can tell you something about the ecology of a given ecosystem. This is because the morphology of individuals reflects their evolutionary history and ecology, and imparts a distinct ‘look’ to communities—making it possible to immediately discern between deserts and forests, or coral reefs and abyssal plains. Once quantified, morphology can provide a common metric for characterizing communities across space and time and, if measured rapidly, serve as a powerful tool for quantifying biotic dynamics. Here, we present and test a new high-throughput approach for analysing community shape in the fossil record using semi-three-dimensional (3D) morphometrics from vertically stacked images (light microscopic or photogrammetric). We assess the potential informativeness of community morphology in a first analysis of the relationship between 3D morphology, ecology and phylogeny in 16 extant species of planktonic foraminifera—an abundant group in the marine fossil record—and in a preliminary comparison of four assemblages from the North Atlantic. In the species examined, phylogenetic relatedness was most closely correlated with ecology, with all three ecological traits examined (depth habitat, symbiont ecology and biogeography) showing significant phylogenetic signal. By contrast, morphological trees (based on 3D shape similarity) were relatively distantly related to both ecology and phylogeny. Although improvements are needed to realize the full utility of community morphometrics, our approach already provides robust volumetric measurements of assemblage size, a key ecological characteristic.

scholarly journals The effects of geographic range size and abundance on extinction during a time of “sluggish”’ evolution

Paleobiology ◽  
2020 ◽  
pp. 1-14
Author(s):  
Michelle M. Casey ◽  
Erin E. Saupe ◽  
Bruce S. Lieberman
Keyword(s):  
North American ◽  
Fossil Record ◽  
Extinction Risk ◽  
Geographic Range ◽  
Range Size ◽  
Late Paleozoic ◽  
The North ◽  
Geographic Range Size ◽  
The Relationship ◽  
Habitat Tracking

Abstract Geographic range size and abundance are important determinants of extinction risk in fossil and extant taxa. However, the relationship between these variables and extinction risk has not been tested extensively during evolutionarily “quiescent” times of low extinction and speciation in the fossil record. Here we examine the influence of geographic range size and abundance on extinction risk during the late Paleozoic (Mississippian–Permian), a time of “sluggish” evolution when global rates of origination and extinction were roughly half those of other Paleozoic intervals. Analyses used spatiotemporal occurrences for 164 brachiopod species from the North American midcontinent. We found abundance to be a better predictor of extinction risk than measures of geographic range size. Moreover, species exhibited reductions in abundance before their extinction but did not display contractions in geographic range size. The weak relationship between geographic range size and extinction in this time and place may reflect the relative preponderance of larger-ranged taxa combined with the physiographic conditions of the region that allowed for easy habitat tracking that dampened both extinction and speciation. These conditions led to a prolonged period (19–25 Myr) during which standard macroevolutionary rules did not apply.

scholarly journals Estimation of sinking velocities using free-falling dynamically scaled models: foraminifera as a test case

2020 ◽  
Author(s):  
Matthew Walker ◽  
Stuart Humphries ◽  
Rudi Schuech
Keyword(s):  
Planktonic Foraminifera ◽  
Physical Models ◽  
Dynamic Scaling ◽  
Test Case ◽  
Dimensionless Numbers ◽  
Settling Particles ◽  
Extant Species ◽  
3D Printed ◽  
Sinking Velocities ◽  
Free Falling

AbstractThe velocity of settling particles is an important determinant of distribution in extinct and extant species with passive dispersal mechanisms, such as plants, corals, and phytoplankton. Here we adapt dynamic scaling, borrowed from engineering, to determine settling velocities. Dynamic scaling leverages physical models with relevant dimensionless numbers matched to achieve similar dynamics to the original object. Previous studies have used flumes, wind tunnels, or towed models to examine fluid flows around objects with known velocities. Our novel application uses free-falling models to determine the unknown sinking velocities of planktonic foraminifera – organisms important to our understanding of the Earth’s current and historic climate. Using enlarged 3D printed models of microscopic foraminifera tests, sunk in viscous mineral oil to match their Reynolds numbers and drag coefficients, we predict sinking velocities of real tests in seawater. This method can be applied to study other settling particles such as plankton, spores, or seeds.Summary StatementWe developed a novel method to determine the sinking velocities of biologically important microscale particles using 3D printed scale models.

A three-dimensional gravity model of the southern contact of the Sebago pluton, Maine

1998 ◽  
Vol 35 (6) ◽  
pp. 649-656 ◽  
Author(s):  
Mark D Behn ◽  
J Dykstra Eusden, Jr. ◽  
John A Notte III
Keyword(s):  
Three Dimensional ◽  
Average Thickness ◽  
Uniform Thickness ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Metasedimentary Rocks ◽  
The North ◽  
Dimensional Gravity ◽  
Relationship Of ◽  
The Relationship

The Sebago pluton is a two-mica granite that intruded the metasedimentary rocks of the Central Maine Terrane around 292 Ma. In recent years, geologists have raised an increasing number of questions related to the overall thickness of the Sebago pluton and the position of its subsurface contact with the underlying metasedimentary rocks. Past studies have shown the Sebago pluton to be a thin, 1-2 km thick, subhorizontal sheet dipping 3° to the northeast. This study examines anomalies in the Earth's gravitational field related to the southern portion of the Sebago pluton, specifically to determine the thickness of the pluton and to locate the subsurface contact between the pluton and the underlying metasedimentary rocks. A three-dimensional model shows the thickest portions of the pluton (~1.8 km) to occur at the bottom of a bowl hape along the southwestern contact. Moreover, the model shows the pluton to thin toward the northern and eastern regions of the study area, where the average thickness is less than 0.5 km. The pluton appears to extend southward below the cover of the metasedimentary rocks along the southwestern contact. Thus, contrary to previous models, the Sebago pluton is not a northeasterly dipping sheet of uniform thickness, but rather an arched sheet with an irregular thickness extending beneath the metasedimentary rocks along both its northern and southern contacts. Based on this new geometry, either the relationship of the pluton to the surrounding metamorphic zones must be modified, or the possibility must be considered that the Sebago pluton is actually a composite batholith, composed of a younger (Permian) granite to the north and an older (Carboniferous) granite to the south.

Stratification and Oxygen Isotopes in the Paleozoic: Is Paleotermometry in Hot Water?

1998 ◽  
Vol 4 ◽  
pp. 244-254 ◽  
Author(s):  
Peter A. Allison ◽  
Rupert Ford ◽  
Richard Corfield
Keyword(s):  
Oxygen Isotopes ◽  
Fossil Record ◽  
Empirical Studies ◽  
Planktonic Foraminifera ◽  
Hot Water ◽  
Glacial Ice ◽  
Deep Waters ◽  
Isotope Method ◽  
Temperature Component ◽  
The Relationship

The oxygen isotope method is probably the most widely used proxy of paleotemperature determination in the fossil record. The relationship as first proposed by Urey (1947) suggests that the ratio of 18O to 16O in the calcitic shells of fossils is proportional to temperature. This was subsequently confirmed by empirical studies (Epstein et al, 1951, Emiliani, 1954; 1955). However, Shackleton (1967), suggested on the basis of co-variance of benthonic and planktonic foraminifera, that the δ18O composition of seawater varied only as a function of glacial ice growth and decay. However, more recent studies have shown that there is still a residual temperature component in the δ18O variability of deep waters.

scholarly journals Under pressure: the relationship between cranial shape and burrowing force in caecilians (Gymnophiona)

2021 ◽  
Author(s):  
Aurélien Lowie ◽  
Barbara De Kegel ◽  
Mark Wilkinson ◽  
John Measey ◽  
James C. O'Reilly ◽  
...  
Keyword(s):  
Phylogenetic Signal ◽  
Three Dimensional ◽  
Form And Function ◽  
Biomechanical Models ◽  
Cranial Osteology ◽  
Head Morphology ◽  
And Function ◽  
The Relationship ◽  
Cranial Shape

Caecilians are elongate, limbless, and annulated amphibians that, with the exception of one aquatic family, all have an at least partly fossorial lifestyle. It has been suggested that caecilian evolution resulted in sturdy and compact skulls with fused bones and tight sutures, as an adaptation to their head-first burrowing habits. However, although their cranial osteology is well described, relationships between form and function remain poorly understood. In the present study, we explored the relationship between cranial shape and in vivo burrowing forces. Using µCT-data, we performed three-dimensional geometric morphometrics to explore whether cranial and mandibular shapes reflected patterns that might be associated with maximal push forces. The results highlight important differences in maximal push forces, with the aquatic Typhlonectes producing a lower force for a given size compared to other species. Despite substantial differences in head morphology across species, no relation between overall skull shape and push force could be detected. Although a strong phylogenetic signal may partly obscure the results, our conclusions confirm previous studies using biomechanical models and suggest that differences in the degree of fossoriality do not appear to be driving the evolution of head shape.

scholarly journals Estimation of sinking velocities using free-falling dynamically scaled models: foraminifera as a test case

2020 ◽  
pp. jeb.230961
Author(s):  
Matthew Walker ◽  
Jörg U. Hammel ◽  
Fabian Wilde ◽  
Tatjana Hoehfurtner ◽  
Stuart Humphries ◽  
...  
Keyword(s):  
Planktonic Foraminifera ◽  
Physical Models ◽  
Dynamic Scaling ◽  
Test Case ◽  
Dimensionless Numbers ◽  
Settling Particles ◽  
Extant Species ◽  
Sinking Velocities ◽  
Scaled Models ◽  
Free Falling

The velocity of settling particles is an important determinant of distribution in extinct and extant species with passive dispersal mechanisms, such as plants, corals, and phytoplankton. Here we adapt dynamic scaling, borrowed from engineering, to determine settling velocities. Dynamic scaling leverages physical models with relevant dimensionless numbers matched to achieve similar dynamics to the original object. Previous studies have used flumes, wind tunnels, or towed models to examine fluid flows around objects with known velocities. Our novel application uses free-falling models to determine the unknown sinking velocities of planktonic foraminifera – organisms important to our understanding of the Earth's current and historic climate. Using enlarged 3D printed models of microscopic foraminifera tests, sunk in viscous mineral oil to match their Reynolds numbers and drag coefficients, we predict sinking velocities of real tests in seawater. This method can be applied to study other settling particles such as plankton, spores, or seeds.

Does extinction wield an axe or pruning shears? How interactions between phylogeny and ecology affect patterns of extinction

Paleobiology ◽  
2011 ◽  
Vol 37 (1) ◽  
pp. 72-91 ◽  
Author(s):  
Walton A. Green ◽  
Gene Hunt ◽  
Scott L. Wing ◽  
William A. DiMichele
Keyword(s):  
Phylogenetic Relationships ◽  
Fossil Record ◽  
Planktonic Foraminifera ◽  
Extinction Probability ◽  
Ecological Change ◽  
Ecological Traits ◽  
Ecological Preferences ◽  
Size Number ◽  
Ecological Criteria ◽  
Close Relatives

Extinctions are caused by environmental and ecological change but are recognized and measured in the fossil record by the disappearance of clades or lineages. If the ecological preferences of lineages or taxa are weakly congruent with their phylogenetic relationships, even large ecological perturbations are unlikely to drive major clades extinct because the factors that eliminate some species are unlikely to affect close relatives with different ecological preferences. In contrast, if phylogenetic relatedness and ecological preferences are congruent, then ecological perturbations can more easily cause extinctions of large clades. In order to quantify this effect, we used a computer model to simulate the diversification and extinction of clades based on ecological criteria. By varying the parameters of the model, we explored (1) the relationship between the extinction probability for a clade of a given size (number of terminals) and the overall intensity of extinction (the proportion of the terminals that go extinct), and (2) the congruence between ecological traits of the terminals and their phylogenetic relationships. Data from two extinctions (planktonic foraminifera at the Eocene/Oligocene boundary and vascular land plants at the Middle/Late Pennsylvanian boundary) show phylogenetic clustering of both ecological traits and extinction probability and demonstrate the interaction of these factors. The disappearance of large clades is observed in the fossil record, but our model suggests that it is very improbable without both high overall extinction intensities and high congruence between ecology and phylogeny.

scholarly journals Factors Influencing Porosity in Planktonic Foraminifera

2018 ◽  
Author(s):  
Janet E. Burke ◽  
Willem Renema ◽  
Michael J. Henehan ◽  
Leanne E. Elder ◽  
Catherine V. Davis ◽  
...  
Keyword(s):  
Fossil Record ◽  
Planktonic Foraminifera ◽  
Critical Role ◽  
Environmental Drivers ◽  
Geochemical Data ◽  
Metabolic Rates ◽  
Key Factors ◽  
Globigerinoides Ruber ◽  
The North ◽  
Random Forest Models

Abstract. The clustering of mitochondria near pores in the test walls of foraminifera suggests that these perforations play a critical role in metabolic gas exchange. As such, pore measurements could provide a novel means of tracking changes in metabolic rate in the fossil record. However, in planktonic foraminifera, variation in pore size, density, and porosity have been variously attributed to environmental, biological, and taxonomic drivers, complicating such an interpretation. Here we examine the environmental, biological, and evolutionary determinants of porosity in 718 individuals representing 17 morphospecies of planktonic foraminifera from 6 core tops in the North Atlantic. Using random forest models, we find that porosity is primarily correlated to size and habitat temperature, two key factors in determining metabolic rates. In order to test if this correlation arose spuriously through the association of cryptic species with distinct biomes, we cultured Globigerinoides ruber in three different temperature conditions, and found that porosity increased with temperature. Crucially, these results show that porosity can be plastic: changing in response to environmental drivers within the lifetime of an individual foraminifer. This demonstrates the potential of porosity as a proxy for foraminiferal metabolic rates, with significance for interpreting geochemical data and the physiology of foraminifera in non-analog environments. It also highlights the importance of phenotypic plasticity (i.e., ecophenotypy) in accounting for some aspects of morphological variation in the modern and fossil record.

Rola Avarského Kaganátu Pri Vzniku Slovenčiny

2018 ◽  
Vol 69 (2) ◽  
pp. 199-236
Author(s):  
Martin Braxatoris ◽  
Michal Ondrejčík
Keyword(s):  
Slavic Language ◽  
The West ◽  
The North ◽  
Danube Region ◽  
The Absolute ◽  
North Edge ◽  
The Relationship ◽  
Slovak Language

Abstract The paper proposes a basis of theory with the aim of clarifying the casual nature of the relationship between the West Slavic and non-West Slavic Proto-Slavic base of the Slovak language. The paper links the absolute chronology of the Proto-Slavic language changes to historical and archaeological information about Slavs and Avars. The theory connects the ancient West Slavic core of the Proto-Slavic base of the Slovak language with Sclaveni, and non-West Slavic core with Antes, which are connected to the later population in the middle Danube region. It presumes emergence and further expansion of the Slavic koiné, originally based on the non-West Slavic dialects, with subsequent influence on language of the western Slavic tribes settled in the north edge of the Avar Khaganate. The paper also contains a periodization of particular language changes related to the situation in the Khaganate of that time.

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