Evaluating the Relationship between Pedofacies and Faunal Composition: Implications for Faunal Turnover at the Paleocene-Eocene Boundary

PALAIOS ◽  
2005 ◽  
Vol 20 (4) ◽  
pp. 390-399 ◽  
Author(s):  
W. C. CLYDE
Keyword(s):  
Faunal Composition ◽  
Faunal Turnover ◽  
The Relationship

scholarly journals Preservational, paleoecological, and evolutionary patterns in the Wyoming-Montana Paleogene and Siwalik Neogene records

1992 ◽  
Vol 6 ◽  
pp. 13-13
Author(s):  
Catherine Badgley ◽  
Anna Kay Behrensmeyer ◽  
William S. Bartels ◽  
Thomas M. Bown
Keyword(s):  
Spatial Distribution ◽  
Species Richness ◽  
Fossil Record ◽  
Tectonic Setting ◽  
Sedimentary Environment ◽  
Depositional Environments ◽  
Taxonomic Resolution ◽  
Faunal Composition ◽  
Faunal Turnover ◽  
Historical Series

The Paleocene to early Eocene sequence of Wyoming-Montana and the Miocene to Pleistocene Siwalik record of Pakistan are exceptionally long, continental sequences, each containing a rich and well documented fossil record, especially of mammals. The two sequences are broadly similar in tectonic setting and sedimentary environment, in duration and facies changes, and in diversity of fossils. Each contains a paleoclimatic record in stable isotopes and, in the Paleogene, floras. Comparison of these two sequences has focused our attention on the interaction of tectonic, climatic, sedimentologic, and taphonomic factors that produce a particular fossil record and on the co-occurring ecological and evolutionary changes that result in a historical series of biotas, each the product of local and global events.In the Paleogene record, the geographic scope of the record encompasses much of the floodbasin, and the spatial distribution of paleoenvironments formed fairly straightforward gradients from channel to distal floodplain. The Siwalik record has a smaller window onto a larger, heterogeneous fluvial system often with multiple, contemporaneous river systems that differ in magnitude. The spatial distribution of paleoenvironments was a mosaic without long proximal to distal gradients. In both records, major facies changes are correlated with striking changes in fossil productivity.The overall pattern of fossil preservation by depositional environment differs substantially in the two areas. The Siwalik sequence has a greater variety of depositional environments that produce fossils throughout the section. The primary productive environment in the older part of the Paleocene record declined in productivity upsection, while a previously unproductive facies became the major source of fossils. Much of the record represents attritional accumulation in each area, but a significant portion is transported. The taphonomic processes that created fossil concentrations led to better taxonomic resolution for most Paleogene localities than in most Siwalik localities.In each record, both aquatic and terrestrial components of the vertebrate faunas are correlated with facies. Since facies varied in productivity over time, some changes in faunal composition may have resulted from change in the prevalence or productivity of particular facies. At least one faunal turnover coincided with major facies changes in each sequence.For mammals in each record, immigration rather than speciation in situ was the primary means of appearance of new species. Episodes of immigration were not closely followed by extinctions of resident species. Mean species longevity appears to have been more than twice as great in the Neogene than in the Paleogene record. Changes in faunal composition and species richness occurred during times of global climatic change; causal connections are still being explored. Changes in species richness did not track changes in relative abundance of taxa or changes in size within lineages or faunas. In terms of guild structure, the herbivore guild had high relative generic diversity through most of both sequences. The Paleogene record had a more even distribution of taxa in the five principal guilds, while the Siwalik record was heavily dominated by the herbivore guild. Size distributions differed substantially, reflecting the early and late windows into the mammalian radiation, rather than sampling bias.

scholarly journals The depth distribution of Ostracoda from the Greenland Sea

1998 ◽  
Vol 17 (1) ◽  
pp. 15-32 ◽  
Author(s):  
Robin Whatley ◽  
Michael Eynon ◽  
Alicia Moguilevsky
Keyword(s):  
North Atlantic ◽  
Deep Sea ◽  
Depth Distribution ◽  
Recent Sediment ◽  
Faunal Turnover ◽  
The North ◽  
The North Atlantic ◽  
The Relationship ◽  
Lower Slope ◽  
Upper Slope

Abstract. Sixteen box core samples of Recent sediment collected in three transects across the East Greenland shelf and slope were analysed for Ostracoda. The samples which range in depth from 274 m to 3355 m, yielded a total of 52 species belonging to 25 genera. No less than 26 of the species also occur in the adjacent Scoresby Sund fjord complex. The fauna represents an interesting mixture of high latitude shallow water Arctic species and others known from bathyal and abyssal depths in the North Atlantic, including some pandemic deep sea species. Many species occur in shallower water here than in the North Atlantic due to the colder water. The fauna comprised of three associations (Shelf/Upper Slope; Slope: Lower Slope/Abyss). A marked faunal turnover occurs at the Upper Slope. The study raises questions concerning the constancy and universality of the relationship between certain ostracod species and water masses.

scholarly journals Upper Triassic and Lower Jurassic stratigraphy from exploration well L134/5-1, offshore Inner Hebrides, west Scotland

2001 ◽  
Vol 20 (2) ◽  
pp. 155-168 ◽  
Author(s):  
Nigel R. Ainsworth ◽  
Ian Boomer
Keyword(s):  
Sea Level ◽  
Lower Jurassic ◽  
Upper Triassic ◽  
Sedimentary Sequence ◽  
Sea Level Changes ◽  
Faunal Composition ◽  
Faunal Turnover ◽  
Northwest Europe ◽  
Published Account ◽  
Exploration Well

Abstract. A thick (c.1368 m) Upper Triassic to Lower Jurassic sedimentary sequence from exploration well L134/5-1, offshore Inner Hebrides, has yielded a rich and diverse foraminiferal and ostracod microfauna. Many of the taxa have been previously described throughout northwest Europe. Poor preservation (often due to crushing and/or overgrowth) and low numbers preclude a complete taxonomic review of this material, although changes in the faunal composition, rates of faunal turnover and palaeoenvironmental analyses are discussed. This is the first published account of ostracod and foraminiferal assemblages from the Sea of Hebrides and they indicate that the sediments (argillaceous, arenaceous and carbonates) were deposited in a shelf-marine setting with environmental fluctuations that are possibly the result of local relative sea-level changes.

scholarly journals Teasing Apart Impacts of Human Activity and Regional Drought on Madagascar’s Large Vertebrate Fauna: Insights From New Excavations at Tsimanampesotse and Antsirafaly

2021 ◽  
Vol 9 ◽  
Author(s):  
Laurie R. Godfrey ◽  
Brooke E. Crowley ◽  
Kathleen M. Muldoon ◽  
Stephen J. Burns ◽  
Nick Scroxton ◽  
...  
Keyword(s):  
Human Activity ◽  
Freshwater Ecosystem ◽  
Hypersaline Lake ◽  
Primary Role ◽  
Faunal Composition ◽  
Faunal Turnover ◽  
Terrestrial Vertebrates ◽  
Faunal Assemblages ◽  
Hydroclimate Variability ◽  
Freshwater Mollusks

Madagascar experienced a major faunal turnover near the end of the first millenium CE that particularly affected terrestrial, large-bodied vertebrate species. Teasing apart the relative impacts of people and climate on this event requires a focus on regional records with good chronological control. These records may document coeval changes in rainfall, faunal composition, and human activities. Here we present new paleontological and paleoclimatological data from southwestern Madagascar, the driest part of the island today. We collected over 1500 subfossil bones from deposits at a coastal site called Antsirafaly and from both flooded and dry cave deposits at Tsimanampesotse National Park. We built a chronology of Late Holocene changes in faunal assemblages based on 65 radiocarbon-dated specimens and subfossil associations. We collected stalagmites primarily within Tsimanampesotse but also at two additional locations in southern Madagascar. These provided information regarding hydroclimate variability over the past 120,000 years. Prior research has supported a primary role for drought (rather than humans) in triggering faunal turnover at Tsimanampesotse. This is based on evidence of: (1) a large freshwater ecosystem west of what is now the hypersaline Lake Tsimanampesotse, which supported freshwater mollusks and waterfowl (including animals that could not survive on resources offered by the hypersaline lake today); (2) abundant now-extinct terrestrial vertebrates; (3) regional decline or disappearance of certain tree species; and (4) scant local human presence. Our new data allow us to document the hydroclimate of the subarid southwest during the Holocene, as well as shifts in faunal composition (including local extirpations, large-vertebrate population collapse, and the appearance of introduced species). These records affirm that climate alone cannot have produced the observed vertebrate turnover in the southwest. Human activity, including the introduction of cattle, as well as associated changes in habitat exploitation, also played an important role.

scholarly journals Lower Jurassic Ostracod Biozonation of the Mochras Borehole

1991 ◽  
Vol 9 (2) ◽  
pp. 205-218 ◽  
Author(s):  
Ian D. Boomer
Keyword(s):  
New Species ◽  
New Taxa ◽  
Lower Jurassic ◽  
Faunal Composition ◽  
Faunal Turnover ◽  
Taxonomic Review ◽  
Present Section ◽  
Jurassic Sequence

Abstract. The extensive Lower Jurassic sequence at Mochras has yielded a diverse ostracod fauna which includes many new taxa. Poor preservation precludes a complete taxonomic review of this material although four new species (Cytherella praetoarcensis, Ogmoconcha convexa, Lophodentina striata and Oligocythereis? mochrasensis) are erected herein. Changes in the faunal composition and the rates of faunal turnover are briefly described. An ostracod biozonation is proposed for the section, comparison with established Lower Jurassic zonal schemes reveals that the present section is distinct from most other European sequences.

scholarly journals EARLY–MIDDLE ORDOVICIAN SEASCAPE-SCALE AGGREGATION PATTERN OF SPONGE-RICH REEFS ACROSS THE LAURENTIA PALEOCONTINENT

Palaios ◽  
2020 ◽  
Vol 35 (12) ◽  
pp. 524-542
Author(s):  
BJÖRN KRÖGER ◽  
AMELIA PENNY
Keyword(s):  
Growth Patterns ◽  
Hard Substrate ◽  
Reef Growth ◽  
Faunal Composition ◽  
Middle Ordovician ◽  
Early Ordovician ◽  
Late Cambrian ◽  
Aggregation Pattern ◽  
The Relationship ◽  
Sediment Matrix

ABSTRACT During the late Cambrian–Early Ordovician interval the predominant non-microbial reef builders were sponges or sponge-like metazoans. The lithological and faunal composition of Cambro-Ordovician sponge-dominated reefs have previously been analyzed and reviewed. Here we take the relationship between reef aggregation pattern at reef to seascape scale into account, and look for changes during the Early–Middle Ordovician interval, in which metazoans became dominant reef builders. In a comparison of sponge-rich reefs from eight sites of the Laurentia paleocontinent three different seascape level reef growth patterns can be distinguished: (1) mosaic mode of reef growth, where reefs form a complex spatial mosaic dependent on hard substrate; (2) episodic mode, where patch reefs grew exclusively in distinct unconformity bounded horizons within non-reefal lithological units that have a much larger thickness; and (3) belt-and-bank mode, where reefs and reef complexes grew vertically and laterally as dispersed patches largely independent from truncation surfaces. The distinct modes of growth likely represent specific reef forming paleocommunities, because they differ in content and abundance of skeletal metazoan framebuilders, bioturbation intensity of non-skeletal reef sediment matrix, and in association of reef growth with underlying hard substrate. We suggest, based on a review of Laurentian reef occurrences, that the mosaic mode dominated in Early Ordovician strata and that the dominance shifted toward the belt and bank mode from Middle Ordovician strata onward.

scholarly journals Patterns of faunal turnover and diversity in the Wyoming-Montana Paleogene in relation to regional and global events

1992 ◽  
Vol 6 ◽  
pp. 191-191
Author(s):  
M.C. Maas ◽  
P.D. Gingerich ◽  
G. Gunnell ◽  
D.W. Krause
Keyword(s):  
Climatic Factors ◽  
Major Effect ◽  
Taxonomic Composition ◽  
Bighorn Basin ◽  
Early Eocene ◽  
Turnover Rates ◽  
Faunal Composition ◽  
Faunal Turnover ◽  
Late Paleocene ◽  
Reversal Record

The Bighorn Basin of Wyoming and its northerly extension, the Crazy Mountains Basin of Montana, contain a continuous record of the middle Paleocene through early Eocene mammalian biota. This interval, spanning some eight million years, is subdivided into 18 faunal zones. Durations of the zones, ranging from 0.3 to 0.75 million years, are extrapolated from intrabasinal depositional rates and correlated with the early Tertiary paleomagnetic reversal record. This stratigraphic resolution allows us to document in detail regional diversity and turnover.In the Bighorn and Crazy Mountains basins, standing generic richness (estimated number of genera at the midpoint of an interval) decreased slightly between the Torrejonian and Tiffanian (middle and late Paleocene), increased from the latest Tiffanian and Clarkforkian (latest Paleocene) to the early Wasatchian (early Eocene), and declined during the later Wasatchian.Changes in diversity reflect first and last appearances (including originations, extinctions, and dispersal). Because first and last appearance rates are in part dependent on diversity and the duration of each interval, we plot generic turnover as rate quotients, ratios of observed to expected first or last appearances. Expected turnover rates are calculated from multiple regression of turnover on duration and generic richness. Turnover rates are evaluated in relation to the quality of the fossil record for each interval. Rate quotients show that the slight decline in generic richness in the Bighorn and Crazy Mountains basins between the Torrejonian and Tiffanian resulted from a higher than expected disappearance rate at the end of the Torrejonian. Lower than expected disappearance rates and higher than expected appearance rates in the early Clarkforkian and, particularly, the earliest Wasatchian contributed to the increase in richness during this period. The middle through late Wasatchian decline in generic richness resulted from surprisingly low appearance and high disappearance rates.There was little change in taxonomic composition of faunas between the middle and late Paleocene; faunas from this interval were dominated by archaic groups (e.g., “condylarths”, multituberculates, plesiadapiforms). In contrast, faunal composition changed markedly during the latest Paleocene and the early Wasatchian, with the introduction of major modern groups (e.g., rodents, artiodactyls, perissodactyls, primates) and the decline in diversity of the archaic forms that dominated earlier Paleocene faunas. There is strong evidence that this faunal change was influenced by global climatic factors: climatic warming, beginning in the latest Paleocene, opened new routes for intercontinental dispersal, and had a major effect on worldwide patterns of faunal composition and diversity, including those of the Bighorn and Crazy Mountains basins.

Interstellar gas in the central region of the Galaxy

1967 ◽  
Vol 31 ◽  
pp. 239-251 ◽  
Author(s):  
F. J. Kerr
Keyword(s):  
Central Region ◽  
Galactic Plane ◽  
Neutral Hydrogen ◽  
Continuum Emission ◽  
Galactic Centre ◽  
Interstellar Gas ◽  
Hydrogen Recombination ◽  
The Galaxy ◽  
Centre Region ◽  
The Relationship

A review is given of information on the galactic-centre region obtained from recent observations of the 21-cm line from neutral hydrogen, the 18-cm group of OH lines, a hydrogen recombination line at 6 cm wavelength, and the continuum emission from ionized hydrogen.Both inward and outward motions are important in this region, in addition to rotation. Several types of observation indicate the presence of material in features inclined to the galactic plane. The relationship between the H and OH concentrations is not yet clear, but a rough picture of the central region can be proposed.

The relationship of the scleractinian corals to the rugose corals

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver
Keyword(s):  
Critical Points ◽  
Scleractinian Corals ◽  
Convincing Evidence ◽  
Early Triassic ◽  
Rugose Corals ◽  
History Of ◽  
The Subject ◽  
Relationship Of ◽  
The Relationship ◽  
Biologic Factors

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.

Choosing a Markov blanket

2020 ◽  
Vol 43 ◽  
Author(s):  
Thomas Parr
Keyword(s):  
Markov Blanket ◽  
Target Article ◽  
The Relationship

Abstract This commentary focuses upon the relationship between two themes in the target article: the ways in which a Markov blanket may be defined and the role of precision and salience in mediating the interactions between what is internal and external to a system. These each rest upon the different perspectives we might take while “choosing” a Markov blanket.

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