scholarly journals The role of environment in the diversity and evolutionary turnover rates of the Foraminiferida

1992 ◽  
Vol 6 ◽  
pp. 278-278 ◽  
Author(s):  
S.W. Starratt
Keyword(s):  
Shallow Water ◽  
Sea Level ◽  
Deep Water ◽  
Taxonomic Diversity ◽  
Late Paleozoic ◽  
Ecological Niches ◽  
Time Interval ◽  
Turnover Rates ◽  
Extinction Event

Taxonomic databases are important tools in the study of faunal diversity and evolution. The usefulness of the inferences drawn from these databases is diminished when the role of environment is not considered. Analysis of the foraminiferal database at the genus and family levels is used to demonstrate the effect of water depth on presumed changes in taxonomic diversity and evolutionary turnover rates.This paleoenvironmental effect is particularly noticeable when foraminiferal faunas of the late Paleozoic and the Mesozoic and Cenozoic intervals are compared. The late Paleozoic fauna is dominated by the Fusulinina and shallow-water (0–200 m) Textularuna. Standing diversity fluctuates greatly, and evolutionary turnover is high. This reflects short-term fluctuations in sea level which led to the rapid formation and destruction of narrow ecological niches. Evolutionary turnover appears to be related to reef growth during this time. This trend may also reflect an increased number of k-selected specialists which serve as proxy indicators for a slow-circulating oligotrophic ocean system. Shallow-water taxa may also be predisposed to extinction due to their reliance on symbiotic algae. The extinction event at the end of the Permian resulted in the loss of almost 70% of the standing generic diversity. This included the complete loss of the Fusulinina as well as a number of shallow-water textularids. Cohort survivorship curves are steep and taxon ages short during this time.The diversity increase over the past 245 million years has largely been due to the addition of deep-water (200-10,000 m) taxa. This was particularly true during the Late Cretaceous and early Eocene, and may reflect the relatively high eustatic sea level during those intervals. The relationship between reef development and evolutionary turnover rates is less clear during this time interval. Although the extinction event that marked the end of the Cretaceous resulted in a greater loss in absolute taxonomic diversity than occurred at the end of the Permian, the relative loss in generic diversity was only about 21% due to the large number of deep-water taxa. When the entire fauna is considered, cohort survivorship curves are less steep and taxon ages are longer than in the late Paleozoic, but when only the shallow-water taxa are considered, the results are similar to those for the late Paleozoic.

Onset of the Late Paleozoic Glacioeustatic Signal: A Stratigraphic Record from the Paleotropical, Oil-Shale-Bearing Big Snowy Trough of Central Montana, U.S.A.

2019 ◽  
Vol 89 (8) ◽  
pp. 761-783 ◽  
Author(s):  
Justin P. Ahern ◽  
Christopher R. Fielding
Keyword(s):  
Sea Level ◽  
Ice Age ◽  
Late Paleozoic ◽  
Time Interval ◽  
Relative Sea Level ◽  
Depositional Sequences ◽  
Sea Level Fluctuations ◽  
Shark Bay ◽  
Facies Associations ◽  
Central Montana

Abstract In the Big Snowy Mountains of central Montana, USA, late Visean to Bashkirian strata preserve a nearly complete, but poorly documented, paleotropical stratigraphic succession that straddles the range of current estimates of the onset of the Late Paleozoic Ice Age (LPIA). Sedimentologic and stratigraphic investigation of the Otter (late Visean to Serpukhovian) and Heath (Serpukhovian) formations, with secondary focus on the overlying Tyler (late Serpukhovian to Bashkirian) and Alaska Bench (Bashkirian) formations, facilitated an appraisal of paleotropical environmental change preserved in this succession. Three facies associations reminiscent of environments currently forming in Shark Bay, Australia, were identified in the Otter Formation: shallow semi-restricted littoral platform, intertidal platform, and supratidal plain. Five facies associations broadly comparable to modern environments present in the Sunda Shelf and southern coast of the Persian Gulf were identified in the Heath Formation: offshore outer ramp, mid- to outer ramp, inner ramp, coastal plain, and sabkha. Facies associations preserved in the Heath Formation are here explained in the context of a protected, homoclinal carbonate ramp situated in a partially silled epicontinental embayment. A shift from low-magnitude relative sea-level oscillations preserved in the Otter Formation to a cyclothemic stratigraphic pattern entailing ≥ 6 fourth-order, high-frequency and high-magnitude relative sea-level fluctuations in the Heath Formation is here interpreted to record the main eustatic signal of the LPIA in central Montana. Current published biostratigraphic constraints for the observed stratigraphy estimate the main eustatic signal of the LPIA to have occurred approximately between 331 (base Serpukhovian) and 327 Ma in central Montana. A distinct upward transition from coal and paleosol-bearing depositional sequences in the lower Heath to evaporite and limestone-bearing depositional sequences in the upper Heath preserves a broad humid to arid paleoclimate shift during deposition of this unit, which influenced hydrographic circulation patterns and the resultant distribution of anoxic environments in the Big Snowy Trough during this time interval. Improved depositional and sequence stratigraphic models of the Heath Formation proposed in this study permit new insight into the theoretical distribution of, and water depth necessary to preserve, black, organic-rich claystone and shale in partially silled intracratonic basins, in addition to new temporal constraints on LPIA onset in paleotropical western Laurentia.

Description of two new fossil echinoids (Echinodermata: Echinoidea) from the Early Hauterivian (Early Cretaceous) of the Paris Basin (France)

Zootaxa ◽  
2012 ◽  
Vol 3512 (1) ◽  
pp. 75 ◽  
Author(s):  
THOMAS SAUCÈDE ◽  
JEAN-CHRISTOPHE DUDICOURT ◽  
PHILIPPE COURVILLE
Keyword(s):  
Shallow Water ◽  
Sea Level ◽  
Early Cretaceous ◽  
Benthic Invertebrates ◽  
Western Europe ◽  
Time Interval ◽  
Equal Proportion ◽  
Paris Basin ◽  
Time Period ◽  
High Level

Two new echinoid genera and species, Salvaster roberti gen. et sp. nov. and Pygolampas edita gen. et sp. nov. are de-scribed. They were collected in the Calcaires à Spatangues Formation (CSF) that consists of limestone and clay sedimentsdeposited in the southeast of the Paris Basin (France) during the Early Hauterivian (Early Cretaceous). The CSF is datedfrom the Acanthodiscus radiatus chronozone, a time-interval of overall high sea level in Western Europe, but it yields arich shallow-water fossil fauna mostly represented by benthic invertebrates. Of the 54 echinoid species ever described inthe CSF, 26 species are recognized here. They are distributed into 16 different families, among which regular (13 species)and irregular (13 species) echinoids are represented in equal proportion. This work confirms the high level of echinoid diversity in the CSF for that time-period.

Bathymetric anomalies in the Neogene fossil record: The role of diving marine birds

Paleobiology ◽  
1982 ◽  
Vol 8 (4) ◽  
pp. 402-407 ◽  
Author(s):  
David R. Lindberg ◽  
Michael G. Kellogg
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Fossil Record ◽  
Transport Processes ◽  
Marine Birds ◽  
Trophic Resources ◽  
Northeastern Pacific ◽  
Biological Explanations

Associations of bathymetrically anomalous fossils, a phenomenon particularly common in shallow-water, marine, Neogene faunas of the northeastern Pacific, have yet to be explained adequately. No known physical transport processes can selectively move species upslope from deep water into diverse nearshore, shallow-water habitats. Previously proposed biological explanations are based on undocumented phenomena. We document bathymetric anomalies in Recent mollusc accumulations on Southeast Farallon Island, California, that are created by the activities of diving marine birds. Application of these observations to patterns in the Neogene fossil record is direct, involving the same genera and often the same species. We argue that the process has occurred since at least the Miocene when diving marine birds radiated rapidly, probably in response to trophic resources created by intensive upwelling (Lipps and Mitchell 1976) and that they could have transported specimens upslope in sufficient quantity to have contributed anomalous species to the Neogene fossil record. Specific examples from the literature are discussed.

The role of cephalopods in the world’s oceans: general conclusions and the future

1996 ◽  
Vol 351 (1343) ◽  
pp. 1105-1112 ◽  
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Sampling Methods ◽  
Total Biomass ◽  
Continental Shelves ◽  
Direct Sampling ◽  
Almost All ◽  
Neutrally Buoyant ◽  
Negatively Buoyant

In this volume we have considered the problems of investigation special to cephalopods. Almost all our knowledge of their general biology is restricted to the shelf-living, muscular, negatively buoyant (the Loliginidae and Octopodidae) or gas-supported species (the Sepiidae and Nautilidae) and members of the Ommastrephidae which move on to the continental shelves at certain seasons. These species of the continental shelves comprise only about 15% of all cephalopod genera and live in water of less than 300 m depth, which covers only 6% of the Earth’s surface. They do not represent the majority of cephalopod species or much of their total biomass; 85 % of genera are spread in the upper 2000 m and across the bottom of the deep oceans, which occupy 66 % of the Earth’s surface. Over 40% of these genera are neutrally buoyant by oil or chemical means and may have very different lifestyles from the forms we know from shallow water. Improvement of our knowledge of the ecology of deep water forms is hindered by our poor direct sampling methods and rests largely upon sampling from stomachs or regurgitations of the predators that eat cephalopods.

scholarly journals The influence of environmental setting on the community ecology of Ediacaran organisms

2019 ◽  
Author(s):  
Emily G. Mitchell ◽  
Nikolai Bobkov ◽  
Natalia Bykova ◽  
Alavya Dhungana ◽  
Anton Kolesnikov ◽  
...  
Keyword(s):  
Community Ecology ◽  
Shallow Water ◽  
Deep Water ◽  
Benthic Communities ◽  
Bedding Plane ◽  
Depositional Environments ◽  
Time Interval ◽  
Benthic Environment ◽  
A Chain ◽  
Broad Scale

AbstractThe broad-scale environment plays a substantial role in shaping modern marine ecosystems, but the degree to which palaeocommunities were influenced by their environment is unclear. To investigate how broad-scale environment influenced the community ecology of early animal ecosystems we employed spatial point process analyses to examine the community structure of seven bedding-plane assemblages of late Ediacaran age (558–550 Ma), drawn from a range of environmental settings and global localities. The studied palaeocommunities exhibit marked differences in the response of their component taxa to sub-metre-scale habitat heterogeneities on the seafloor. Shallow-marine palaeocommunities were heavily influenced by local habitat heterogeneities, in contrast to their deep-water counterparts. Lower species richness in deep-water Ediacaran assemblages compared to shallow-water counterparts across the studied time-interval could have been driven by this environmental patchiness, because habitat heterogeneities correspond to higher diversity in modern marine environments. The presence of grazers and detritivores within shallow-water communities may have promoted local patchiness, potentially initiating a chain of increasing heterogeneity of benthic communities from shallow to deep-marine depositional environments. Our results provide quantitative support for the “Savannah” hypothesis for early animal diversification – whereby Ediacaran diversification was driven by patchiness in the local benthic environment.Author ContributionsE. Mitchell conceived this paper and wrote the first draft. N. Bobkov, A. Kolesnikov, N. Sozonov and D. Grazhdankin collected the data for DS surface. N. Bobkov and N. Sozonov performed the analyses on DS surface. N. Bykova, S. Xiao, and D. Grazhdankin collected the data for WS, KH1 and KH2 surfaces and E. Mitchell performed the analyses. A. Dhungana and A. Liu collected the data for FUN4 and FUN5 surfaces and A. Dhungana performed the analyses. T. Mustill and D. Grazhdankin collected the data for KS and T. Mustill and E. Mitchell performed the analyses. I. Hogarth developed the software for preliminary KS surface analyses. E. Mitchell, N. Bobkov, N. Bykova, A. Dhungana, A. Kolesnikov, A. Liu, S. Xiao and D. Grazhdankin discussed the results and prepared the manuscript.

scholarly journals On the diversity of Early Jurassic cartilaginous fishes across the Toarcian Oceanic Anoxic Event

2019 ◽  
Author(s):  
Sebastian Stumpf ◽  
Faviel A. López-Romero ◽  
Jürgen Kriwet
Keyword(s):  
Sea Level ◽  
Abiotic Factors ◽  
Seawater Temperature ◽  
Early Jurassic ◽  
Ecological Niches ◽  
Time Interval ◽  
Diversity Patterns ◽  
Oceanic Anoxic Event ◽  
Anoxic Event ◽  
Diversity Dynamics

The Early Jurassic represents a crucial time interval in the evolutionary history of elasmobranchs, because the Toarcian witnessed a first major diversification, suggesting a profound reorganization of ecological niches of chondrichthyans, probably accompanied by a subsequent diversity decline of hybodontiforms within marine environments. Potential factors underlying the Toarcian elasmobranch radiation event not only include evolutionary novelties in ecological adaptations of swimming, feeding, and reproduction, but also abiotic factors such as increasing seawater temperatures and variations in eustatic sea level associated with the Toarcian Oceanic Anoxic Event (T-OAE). These events might have played an important role in the Toarcian elasmobranch diversification event by regulating diversity dynamics through the availability of higher speciation and dispersal rates. In attempt to better understand macroevolutionary patterns and processes of Jurassic chondrichthyans, we analysed the generic diversity of Pliensbachian to Aalenian elasmobranchs and hybodontiforms and explored their response to the T-OAE. In doing so, we calculated the estimated mean standing diversities (EMSD) using 10 time bins of approximately 2 Myr duration and evaluated the relationships between EMSD and variations in both seawater temperature and eustatic sea level to test whether these parameters affect the observed diversity patterns. Our data indicate profoundly different diversity dynamics of elasmobranchs and hybodontiforms. The EMSD is low in Pliensbachian to Aalenian hybodontiforms, indicating an evolutionary stasis. Conversely, a constant taxonomic increase in elasmobranchs is recorded, spanning from the Pliensbachian to the end of the Toarcian, before reaching a diversity plateau in the Aalenian. These divergent patterns might suggest that hybodontiforms were not competing with elasmobranchs, but more likely are the result of still existing taxonomic misconceptions of Jurassic hybodontiforms, mainly caused by morphological characters that are either ambiguous or broadly distributed among these anatomically rather conservative chondrichthyans. Notwithstanding this, our results indicate that variations in seawater temperature and eustatic sea level changes associated with the T-OAE were not the primary drivers underlying the observed elasmobranch diversity patterns. Therefore, it might be possible that the diversification of elasmobranchs was opportunistic, benefitting from the appearance and subsequent radiation of new food resources, probably in response of enhanced surface productivity during the T-OAE. This hypothesis, however, needs to be tested, pending the inclusion of other time-equivalent marine vertebrate groups in future diversity analyses. Moreover, a detailed re-evaluation of Jurassic hybodontiforms will contribute to our understanding of chondrichthyan diversity dynamics across the T-OAE.

A novel observation of dingoes (Canis lupus dingo) attacking a swimming eastern grey kangaroo (Macropus giganteus)

2010 ◽  
Vol 32 (2) ◽  
pp. 201 ◽  
Author(s):  
Brad V. Purcell
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Canis Lupus ◽  
Functional Role ◽  
New South ◽  
Keystone Species ◽  
Hunting Strategies ◽  
South Wales ◽  
Grey Kangaroo

The dingo (Canis lupus dingo) is a keystone species in Australian ecosystems. The current study reports four dingoes observed attacking a swimming eastern grey kangaroo (Macropus giganteus) in the Wollondilly River, New South Wales. It is proposed that kangaroos need to stand at a certain depth of water to escape an attack by dingoes. If dingoes can continue attacking from opposing directions without threat of injury from the kangaroo, such as in shallow water where dingoes can stand or deep water where kangaroos cannot stand, then the attack may continue until the predator(s) kill the prey or the prey escapes. Further research on such behaviours is needed to understand the functional role of dingoes and the importance of pack structure in development of hunting strategies.

Carboniferous conodont biostratigraphy

2020 ◽  
pp. SP512-2020-38
Author(s):  
James E. Barrick ◽  
Alexander S. Alekseev ◽  
Silvia Blanco-Ferrera ◽  
Natalia V. Goreva ◽  
Keyi Hu ◽  
...  
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Global Distribution ◽  
High Quality ◽  
Conodont Biostratigraphy ◽  
Conodont Biofacies ◽  
Extinction Event ◽  
Water Facies

AbstractCarboniferous conodont biostratigraphy comprises regional zonations that reflect the paleogeographic distribution of taxa and distinct shallow-water and deep-water conodont biofacies. Some species have a global distribution and can effect high quality correlations. These taxa are incorporated into definitions of global Carboniferous chronostratigraphic units. A standard global Carboniferous zonation has not been developed. The lowermost Mississippian is zoned by Siphonodella species, except in shallow-water facies, where other polygnathids are used. Gnathodus species radiated during the Tournaisian and are used to define many Mississippian zones. A late Tournaisian maximum in diversity, characterized by short-lived genera, was followed by lower diversity faunas of Gnathodus species and carminate genera through the Viséan and Serpukhovian. By the late Viséan and Serpukhovian, Lochriea provides better biostratigraphic resolution. Shallow-water zonations based on Cavusgnathus and Mestognathus are difficult to correlate. An extinction event near the base of the Pennsylvanian was followed by the appearance of new gnathodid genera: Rhachistognathus, Declinognathodus, Neognathodus, Idiognathoides, and Idiognathodus. By the middle of the Moscovian, few genera remained: Idiognathodus, Neognathodus and Swadelina. During the middle Kasimovian and Gzhelian, only Idiognathodus and Streptognathodus species were common. Near the end of the Gzhelian, a rediversification of Streptognathodus species extended into the Cisuralian.

The apparatus of the Carboniferous conodont Vogelgnathus simplicatus and the early evolution of the genus

2018 ◽  
Vol 93 (1) ◽  
pp. 126-136
Author(s):  
Javier Sanz-López ◽  
Silvia Blanco-Ferrera ◽  
C. Giles Miller
Keyword(s):  
Shallow Water ◽  
Sea Level ◽  
Species Distribution ◽  
Deep Water ◽  
Early Evolution ◽  
Published Data ◽  
British Isles ◽  
Discrete Elements ◽  
Republic Of Ireland ◽  
The Republic

AbstractThe apparatus of Vogelgnathus simplicatus (Rhodes, Austin, and Druce, 1969) is reconstructed from discrete elements from a sample of limited diversity from the Limerick Province (Ireland). The apparatus is typical of the order Ozarkodinida and the P1 element was previously placed within Gnathodus. Here we assign it to Vogelgnathus by applying a multielemental concept rather than using P1 element morphology. The holotype and paratypes are re-illustrated and the species distribution revised based on published data. Vogelgnathus simplicatus ranges from the late Tournaisian to the early Viséan (Mississippian, Carboniferous), with common occurrences relating to the growth of Waulsortian bank complexes in a high-stand sea-level along the southern and western margins of the Laurussian landmass (Belgium, the British Isles, the Republic of Ireland, and USA). Vogelgnathus simplicatus appears to represent the rootstock from which deep-water and shallow-water Viséan species of Vogelgnathus evolved in the Mississippian.

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