scholarly journals New occurrences of fossilized feathers: systematics and taphonomy of the Santana Formation of the Araripe Basin (Cretaceous), NE, Brazil

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1916 ◽  
Author(s):  
Gustavo M.E.M. Prado ◽  
Luiz Eduardo Anelli ◽  
Setembrino Petri ◽  
Guilherme Raffaeli Romero
Keyword(s):  
Sample Size ◽  
Early Cretaceous ◽  
Fossil Record ◽  
Small Sample Size ◽  
Small Sample ◽  
Exceptional Preservation ◽  
The World ◽  
Crato Member ◽  
Santana Formation ◽  
New Occurrences

Here we describe three fossil feathers from the Early Cretaceous Santana Formation of the Araripe Basin, Brazil. Feathers are the most complex multiform vertebrate integuments; they perform different functions, occurring in both avian and non-avian dinosaurs. Despite their rarity, fossil feathers have been found across the world. Most of the Brazilian feather fossil record comes from the Santana Formation. This formation is composed of two members: Crato (lake) and Romualdo (lagoon); both of which are predominantly reduced deposits, precluding bottom dwelling organisms, resulting in exceptional preservation of the fossils. Despite arid and hot conditions during the Cretaceous, life teemed in the adjacency of this paleolake. Feathered non-avian dinosaurs have not yet been described from the Crato Member, even though there are suggestions of their presence in nearby basins. Our description of the three feathers from the Crato laminated limestone reveals that, despite the small sample size, they can be referred to coelurosaurian theropods. Moreover, based on comparisons with extant feather morphotypes they can be identified as one contour feather and two downy feathers. Despite their rareness and low taxonomic potential, fossilized feathers can offer insights about the paleobiology of its owners and the paleoecology of the Araripe Basin.

scholarly journals New occurrences of fossilized feathers: systematics, taphonomy, and paleoecology of the Santana Formation of the Araripe Basin (Cretaceous), NE, Brazil

2015 ◽  
Author(s):  
Gustavo M. E. M. Prado ◽  
Luiz Eduardo Anelli ◽  
Guilherme Raffaelli Romero
Keyword(s):  
Fossil Record ◽  
Trophic Chain ◽  
Evolutionary Models ◽  
Future Perspectives ◽  
Reducing Conditions ◽  
Time Period ◽  
Crato Member ◽  
Santana Formation ◽  
Diversity Of Life ◽  
New Occurrences

Feathers are the most complex and diversified integuments in vertebrates. Their complexity are provided by the different forms and functions, and they occur both in non-avian and avian-dinosaurs. Despite their rareness, feathers are found throughout the world, and the Santana Formation (comprised by Crato and Romualdo formations) of the Araripe Basin is responsible for the majority of these records in Brazil. Most occurrences is consisted by isolated feathers, where downy-feathers is the recurrent morphotype, two coelurosaurs and one enantiornithe bird. The sedimentary deposition of this unit is consisted by a lacustrine (Crato Fm) and lagoonal (Romualdo Fm) environments, where reducing conditions prevailed, precluding the activity of bottom dwelling organisms that favored the exquisite preservation. Despite the arid and hot conditions during the Cretaceous, life teemed in the adjacency of both paleolakes, however, feathered non-avian dinosaurs were not found yet in the Crato Member. By the great diversity of life that existed in the paleolake surroundings, is possible to recognize, through the fossil record, that a complex and diversified trophic chain was well established during the time period of sedimentation of this unit. When the remains reached the bottom of the paleolakes, the subsequent isolation from the environment allowed their preservation. In this work, three fossilized feathers, consisted of two downy and one contour feather, extracted from the laminated limestone of the Crato Member of the Santana Formation, were described and identified according to morphological and evolutionary models. We also used the terminology commonly applied to extant organisms. Relying on the fossil record of this unit and the adjacencies formations and basins (by autochthonous condition), taxonomic inferences can be made when the lowest hierarchy level is considered, and hence, is possible to propose the plausible taxa that could bear these elements. Taphonomic and paleoecological aspects, such as the preservation of these structures, and the presence of dinosaurs, were also reviewed, as well as the future perspectives about the study of these elements. Despite the virtual low significance, the pragmatical study of fossilized feathers, can help with the understanding of the evolution and paleobiology of dinosaurs, especially on the South Hemisphere.

scholarly journals New occurrences of fossilized feathers: systematics, taphonomy, and paleoecology of the Santana Formation of the Araripe Basin (Cretaceous), NE, Brazil

2015 ◽  
Author(s):  
Gustavo M. E. M. Prado ◽  
Luiz Eduardo Anelli ◽  
Guilherme Raffaelli Romero
Keyword(s):  
Fossil Record ◽  
Trophic Chain ◽  
Evolutionary Models ◽  
Future Perspectives ◽  
Reducing Conditions ◽  
Time Period ◽  
Crato Member ◽  
Santana Formation ◽  
Diversity Of Life ◽  
New Occurrences

Feathers are the most complex and diversified integuments in vertebrates. Their complexity are provided by the different forms and functions, and they occur both in non-avian and avian-dinosaurs. Despite their rareness, feathers are found throughout the world, and the Santana Formation (comprised by Crato and Romualdo formations) of the Araripe Basin is responsible for the majority of these records in Brazil. Most occurrences is consisted by isolated feathers, where downy-feathers is the recurrent morphotype, two coelurosaurs and one enantiornithe bird. The sedimentary deposition of this unit is consisted by a lacustrine (Crato Fm) and lagoonal (Romualdo Fm) environments, where reducing conditions prevailed, precluding the activity of bottom dwelling organisms that favored the exquisite preservation. Despite the arid and hot conditions during the Cretaceous, life teemed in the adjacency of both paleolakes, however, feathered non-avian dinosaurs were not found yet in the Crato Member. By the great diversity of life that existed in the paleolake surroundings, is possible to recognize, through the fossil record, that a complex and diversified trophic chain was well established during the time period of sedimentation of this unit. When the remains reached the bottom of the paleolakes, the subsequent isolation from the environment allowed their preservation. In this work, three fossilized feathers, consisted of two downy and one contour feather, extracted from the laminated limestone of the Crato Member of the Santana Formation, were described and identified according to morphological and evolutionary models. We also used the terminology commonly applied to extant organisms. Relying on the fossil record of this unit and the adjacencies formations and basins (by autochthonous condition), taxonomic inferences can be made when the lowest hierarchy level is considered, and hence, is possible to propose the plausible taxa that could bear these elements. Taphonomic and paleoecological aspects, such as the preservation of these structures, and the presence of dinosaurs, were also reviewed, as well as the future perspectives about the study of these elements. Despite the virtual low significance, the pragmatical study of fossilized feathers, can help with the understanding of the evolution and paleobiology of dinosaurs, especially on the South Hemisphere.

Application of Ultrasound Elastography for Assessing Intestinal Fibrosis in Inflammatory Bowel Disease: Fiction or Reality?

2020 ◽  
Vol 21 ◽  
Author(s):  
Roberto Gabbiadini ◽  
Eirini Zacharopoulou ◽  
Federica Furfaro ◽  
Vincenzo Craviotto ◽  
Alessandra Zilli ◽  
...  
Keyword(s):  
Inflammatory Bowel Disease ◽  
Sample Size ◽  
Bowel Disease ◽  
Small Sample Size ◽  
Shear Wave Elastography ◽  
Small Sample ◽  
Ultrasound Elastography ◽  
Invasive Technique ◽  
Intestinal Fibrosis ◽  
Inflammatory Bowel

Background: Intestinal fibrosis and subsequent strictures represent an important burden in inflammatory bowel disease (IBD). The detection and evaluation of the degree of fibrosis in stricturing Crohn’s disease (CD) is important to address the best therapeutic strategy (medical anti-inflammatory therapy, endoscopic dilation, surgery). Ultrasound elastography (USE) is a non-invasive technique that has been proposed in the field of IBD for evaluating intestinal stiffness as a biomarker of intestinal fibrosis. Objective: The aim of this review is to discuss the ability and current role of ultrasound elastography in the assessment of intestinal fibrosis. Results and Conclusion: Data on USE in IBD are provided by pilot and proof-of-concept studies with small sample size. The first type of USE investigated was strain elastography, while shear wave elastography has been introduced lately. Despite the heterogeneity of the methods of the studies, USE has been proven to be able to assess intestinal fibrosis in patients with stricturing CD. However, before introducing this technique in current practice, further studies with larger sample size and homogeneous parameters, testing reproducibility, and identification of validated cut-off values are needed.

scholarly journals Confirming known planetary trends using a photometrically selected Kepler sample

2020 ◽  
Author(s):  
Jonah T Hansen ◽  
Luca Casagrande ◽  
Michael J Ireland ◽  
Jane Lin
Keyword(s):  
Sample Size ◽  
Robust Statistics ◽  
Narrow Band ◽  
Small Sample Size ◽  
Small Sample ◽  
Fitting Algorithm ◽  
Statistical Studies ◽  
The Rich ◽  
Host Stars ◽  
High Metallicity

Abstract Statistical studies of exoplanets and the properties of their host stars have been critical to informing models of planet formation. Numerous trends have arisen in particular from the rich Kepler dataset, including that exoplanets are more likely to be found around stars with a high metallicity and the presence of a “gap” in the distribution of planetary radii at 1.9 R⊕. Here we present a new analysis on the Kepler field, using the APOGEE spectroscopic survey to build a metallicity calibration based on Gaia, 2MASS and Strömgren photometry. This calibration, along with masses and radii derived from a Bayesian isochrone fitting algorithm, is used to test a number of these trends with unbiased, photometrically derived parameters, albeit with a smaller sample size in comparison to recent studies. We recover that planets are more frequently found around higher metallicity stars; over the entire sample, planetary frequencies are 0.88 ± 0.12 percent for [Fe/H] < 0 and 1.37 ± 0.16 percent for [Fe/H] ≥ 0 but at two sigma we find that the size of exoplanets influences the strength of this trend. We also recover the planet radius gap, along with a slight positive correlation with stellar mass. We conclude that this method shows promise to derive robust statistics of exoplanets. We also remark that spectrophotometry from Gaia DR3 will have an effective resolution similar to narrow band filters and allow to overcome the small sample size inherent in this study.

scholarly journals The use of diversity indices for local assessment of marine sediment quality

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shinya Hosokawa ◽  
Kyosuke Momota ◽  
Anthony A. Chariton ◽  
Ryoji Naito ◽  
Yoshiyuki Nakamura
Keyword(s):  
Community Structure ◽  
Sample Size ◽  
Small Sample Size ◽  
Benthic Communities ◽  
Sediment Quality ◽  
Diversity Indices ◽  
Small Sample ◽  
Species Density ◽  
Local Case ◽  
Two Indices

AbstractDiversity indices are commonly used to measure changes in marine benthic communities. However, the reliability (and therefore suitability) of these indices for detecting environmental change is often unclear because of small sample size and the inappropriate choice of communities for analysis. This study explored uncertainties in taxonomic density and two indices of community structure in our target region, Japan, and in two local areas within this region, and explored potential solutions. Our analysis of the Japanese regional dataset showed a decrease in family density and a dominance of a few species as sediment conditions become degraded. Local case studies showed that species density is affected by sediment degradation at sites where multiple communities coexist. However, two indices of community structure could become insensitive because of masking by community variability, and small sample size sometimes caused misleading or inaccurate estimates of these indices. We conclude that species density is a sensitive indicator of change in marine benthic communities, and emphasise that indices of community structure should only be used when the community structure of the target community is distinguishable from other coexisting communities and there is sufficient sample size.

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