Intrinsic versus extrinsic biases in the fossil record: contrasting the fossil record of echinoids in the Triassic and early Jurassic using sampling data, phylogenetic analysis, and molecular clocks

Paleobiology ◽  
2007 ◽  
Vol 33 (2) ◽  
pp. 310-323 ◽  
Author(s):  
Andrew B. Smith
Keyword(s):  
Fossil Record ◽  
Critical Time ◽  
Lower Jurassic ◽  
Time Interval ◽  
Molecular Clocks ◽  
The Past ◽  
Consistent Feature ◽  
Divergence Estimates ◽  
Lineage Analysis

Four independent lines of evidence, (1) the quality of specimen preservation, (2) taxonomic collection curves, (3) molecular divergence estimates, and (4) ghost lineage analysis of a genus-level cladogram, point to echinoids having a much poorer fossil record in the Triassic than in the Lower Jurassic. Furthermore, preservational differences between Triassic and Lower Jurassic echinoids have remained a consistent feature over 160 years of discovery. Differences exist in how effectively paleontologists have collected the fauna from available outcrops in the Triassic and Lower Jurassic. Collection curves suggest that rocks have been more efficiently searched for their fossils in Europe than elsewhere in the world, and that Lower Jurassic faunas are better sampled from available outcrop than Triassic faunas. The discovery of Triassic taxa has quickened in pace over the past 4 decades (though largely driven by a single Lagerstätte—the St. Cassian beds) while discoveries of new taxa from the Lower Jurassic have slowed. Molecular analysis of extant families and ghost lineage analysis of Triassic and Lower Jurassic genera both point to poorer sampling of Triassic faunas. This difference in the quality of the fossil record may be partially explained by differences in rock outcrop area, as marine sedimentary rocks are much less common in the Triassic than in the Lower Jurassic. However, improving biomechanical design of the echinoid test over this critical time interval was probably as important, and better explains observed preservational trends. Changes in the quality of the echinoid fossil record were thus driven as much by intrinsic biological factors as by sampling patterns.

Longitudinal Voice Outcomes After Type I Gore-tex Thyroplasty for Nonparalytic Glottic Incompetence

2016 ◽  
Vol 126 (1) ◽  
pp. 14-19 ◽  
Author(s):  
Lewis Overton ◽  
Katherine Adams ◽  
Rupali N. Shah ◽  
Robert A. Buckmire
Keyword(s):  
Time Interval ◽  
Type I ◽  
Longitudinal Course ◽  
Time Points ◽  
The Past ◽  
Voice Outcome ◽  
Related Quality ◽  
Postoperative Improvement ◽  
Diagnostic Subgroup

Objective: Type I Gore-tex thyroplasty (GTP) for nonparalytic glottic incompetence (GI) results in significantly improved subjective and perceptual voice outcomes. We endeavored to investigate the longitudinal course of voice outcomes measuring the same patients across time points stratified by diagnostic subgroup. Methods: Seventy-five patients with nonparalytic GI treated with GTP in the past 9 years were retrospectively reviewed and grouped according to their primary diagnoses (atrophy, scar, hypomobility, and paresis). Voice outcome measures, Voice-Related Quality of Life (VRQOL), Glottal Function Index (GFI), and GRBAS (grade, roughness, breathiness, asthenia, and strain) for each individual patient and diagnostic subgroup were grouped by time interval following surgery: 0 to 90 days, 3 to 9 months, 9 to 18 months, 18 to 36 months, 3 to 5 years, and 5 to 10 years. Results: Across all diagnoses, statistically significant improvement in VRQOL was maintained at 3 to 5 years ( P = .03) and GFI at 5 to 10 years ( P = .02). The GRBAS showed statistically significant improvements out to 18 to 36 months ( P = .02). In the subgroup analysis, hypomobility/paresis patients maintained significant improvement voice measures longer than patients with other diagnoses. As a group, scar patients did not show statistically significant postoperative improvement in VRQOL or GFI at any of the tested time points. Conclusions: Gore-tex thyroplasty provides durable improvement in subjective and perceptual voice outcomes for patients with nonparalytic GI. Patients treated for hypomobility/paresis have the most durable vocal outcomes followed by atrophy and lastly, scar.

Testing the time axis of phylogenies

1995 ◽  
Vol 349 (1327) ◽  
pp. 5-10 ◽  
Keyword(s):  
Phylogenetic Analysis ◽  
Fossil Record ◽  
Direct Evidence ◽  
Phylogeny Reconstruction ◽  
Time Axis ◽  
Historical Events ◽  
Subsequent Evolution ◽  
The Past ◽  
Fossil Data

Fossils are not perfect materials for phylogenetic analysis because of problems of missing characters and missing taxa. However, fossils have three major advantages: (1) they give the only direct evidence of the order of acquisition of characters, (2) they frequently present character combinations not found in modern forms, and (3) they may allow the coding of characters that have been overwritten by subsequent evolution within a clade. There are three independent sources of evidence about sequences of historical events in evolution - morphological, molecular and stratigraphic - and these may be mutually cross- tested. Tests of the quality of the fossil record against morphological cladistic data show that (1) age and clade data on branching sequences generally agree, (2) knowledge of the fossil record has improved by 5% over the past 26 years of research, and (3) the fossil record of continental vertebrates is as good as that of (marine) echinoderms. Hence, systematists and evolutionary biologists may use fossil data with confidence in phylogeny reconstruction and to calibrate the time axis of phylogenies.

scholarly journals History is written by the victors: the effect of the push of the past on the fossil record

2017 ◽  
Author(s):  
Graham E. Budd ◽  
Richard P. Mann
Keyword(s):  
Fossil Record ◽  
Molecular Clocks ◽  
Phenotypic Evolution ◽  
Mass Extinctions ◽  
The Past ◽  
Extinction Rates ◽  
The Mean ◽  
Birth Death

AbstractPhylogenies may be modelled using “birth-death” models for speciation and extinction, but even when a homogeneous rate of diversification is used, survivorship biases can generate remarkable rate heterogeneities through time. One such bias has been termed the “push of the past”, by which the length of time a clade has survived is conditioned on the rate of diversification that happened to pertain at its origin. This creates the illusion of a secular rate slow-down through time that is, rather, a reversion to the mean. Here we model the controls on the push of the past, and the effect it has on clade origination times, and show that it largely depends on underlying extinction rates. An extra effect increasing early rates of lineage generation is also seen in large clades. These biases are important but relatively neglected influences on many aspects of diversification patterns, such as diversification spikes after mass extinctions and at the origins of clades; they also influence rates of fossilisation, changes in rates of phenotypic evolution and even molecular clocks. These inevitable features of surviving and/or large clades should thus not be generalised to the diversification process as a whole without additional study of small and extinct clades.

scholarly journals Direct estimation of mutations in great apes reveals significant recent human slowdown in the yearly mutation rate

2018 ◽  
Author(s):  
Søren Besenbacher ◽  
Christina Hvilsom ◽  
Tomas Marques-Bonet ◽  
Thomas Mailund ◽  
Mikkel Heide Schierup
Keyword(s):  
Linear Relationship ◽  
Mutation Rate ◽  
Fossil Record ◽  
Great Apes ◽  
Mutation Rates ◽  
Rate Estimate ◽  
The Past ◽  
Divergence Estimates ◽  
Human Mutation ◽  
Mutation Rate Estimate

AbstractThe human mutation rate per generation estimated from trio sequencing has revealed an almost linear relationship with the age of the father and the age of the mother. The yearly trio-based mutation rate estimate of ~0.43×10−9 is markedly lower than prior indirect estimates of ~1×10−9 per year from phylogenetic comparisons of the great apes. This suggests either a slowdown over the past 10 million years or an inaccurate interpretation of the fossil record. Here we use sequencing of chimpanzee, gorilla and orangutan trios and find that each species has higher estimated mutation rates per year by factors of 1.67+/− 0.22, 1.54+/− 0.2 and 1.84+/− 0.19, respectively. These estimates suggest a very recent and appreciable slowdown in human mutation rate, and, if extrapolated over the great apes phylogeny, yields divergence estimates much more in line with the fossil record and the biogeography.

scholarly journals The Eomyidae in Asia: Biogeography, diversity and dispersals

2020 ◽  
Vol 76 (1) ◽  
pp. 181-200
Author(s):  
Yuri Kimura ◽  
Isaac Casanovas-Vilar ◽  
Olivier Maridet ◽  
Daniela C. Kalthoff ◽  
Thomas Mörs ◽  
...  
Keyword(s):  
North America ◽  
Fossil Record ◽  
Climate Changes ◽  
Genus Level ◽  
The Past ◽  
The Family ◽  
Endemic Genera ◽  
Ecological Shifts ◽  
Dispersal Events

In Asia, the first find of an eomyid rodent was reported almost one century after the first studies of the family Eomyidae in North America and Europe. Since then, eomyid rodents have been increasingly found in Asia particularly over the past two decades. Here, we review the Asian record of this family at the genus level. Currently, 22 species within 14 genera were reported from Asia, including seven endemic genera and rare materials of apeomyine eomyids. Eomyids emphasize the palaeogeographic importance of Asia in considering intercontinental dispersal events of small mammals. With newly compiled data for Asian eomyids, we also compare genus-level diversity trends through time among North America, Europe, and Asia. Despite data standardizations limited with respect to potential biases in the fossil record, we found that the Asian eomyid diversity closely follows ecological shifts induced by climate changes. In general, Asian eomyid genera disappeared earlier than their European counterparts. We suggest that this pattern is not dictated by differences in the quality of the fossil record and is related to the expansion of drier habitats over large areas of Asia.

scholarly journals Exceptionally preserved North American Paleogene metatherians: adaptations and discovery of a major gap in the opossum fossil record

2007 ◽  
Vol 3 (3) ◽  
pp. 318-322 ◽  
Author(s):  
Marcelo Sánchez-Villagra ◽  
Sandrine Ladevèze ◽  
Inés Horovitz ◽  
Christine Argot ◽  
Jeremy J Hooker ◽  
...  
Keyword(s):  
Fossil Record ◽  
Critical Time ◽  
Sister Group ◽  
Early History ◽  
Crown Group ◽  
White River ◽  
Early Oligocene ◽  
History Of ◽  
New Material ◽  
Divergence Estimates

A major gap in our knowledge of the evolution of marsupial mammals concerns the Paleogene of the northern continents, a critical time and place to link the early history of metatherians in Asia and North America with the more recent diversification in South America and Australia. We studied new exceptionally well-preserved partial skeletons of the Early Oligocene fossil Herpetotherium from the White River Formation in Wyoming, which allowed us to test the relationships of this taxon and examine its adaptations. Herpetotheriidae, with a fossil record extending from the Cretaceous to the Miocene, has traditionally been allied with opossums (Didelphidae) based on fragmentary material, mainly dentitions. Analysis of the new material reveals that several aspects of the cranial and postcranial anatomy, some of which suggests a terrestrial lifestyle, distinguish Herpetotherium from opossums. We found that Herpetotherium is the sister group to the crown group Marsupialia and is not a stem didelphid. Combination of the new palaeontological data with molecular divergence estimates, suggests the presence of a long undocumented gap in the fossil record of opossums extending some 45 Myr from the Early Miocene to the Cretaceous.

Immunoferritin localization of intracellular antigens in positively stained frozen sections

1978 ◽  
Vol 36 (2) ◽  
pp. 168-169
Author(s):  
K. T. Tokuyasu
Keyword(s):  
Surface Tension ◽  
Water Surface ◽  
Thin Layers ◽  
The Other ◽  
Positive Staining ◽  
Frozen Sections ◽  
The Past ◽  
Ultrathin Frozen Sections ◽  
Definition Of

During the past investigations of immunoferritin localization of intracellular antigens in ultrathin frozen sections, we found that the degree of negative staining required to delineate u1trastructural details was often too dense for the recognition of ferritin particles. The quality of positive staining of ultrathin frozen sections, on the other hand, has generally been far inferior to that attainable in conventional plastic embedded sections, particularly in the definition of membranes. As we discussed before, a main cause of this difficulty seemed to be the vulnerability of frozen sections to the damaging effects of air-water surface tension at the time of drying of the sections.Indeed, we found that the quality of positive staining is greatly improved when positively stained frozen sections are protected against the effects of surface tension by embedding them in thin layers of mechanically stable materials at the time of drying (unpublished).

Exercise Capacity in Chronic Heart Failure

2012 ◽  
Vol 9 (1) ◽  
pp. 57-60 ◽  
Author(s):  
Gina G Mentzer ◽  
Alex J Auseon
Keyword(s):  
Quality Of Life ◽  
Heart Failure ◽  
Exercise Training ◽  
Exercise Capacity ◽  
Positive Impact ◽  
Pharmacologic Therapy ◽  
The Past ◽  
Diagnosis And Prognosis ◽  
Future Therapy

Heart failure (HF) affects more than 5 million people and has an increasing incidence and cost burden. Patients note symptoms of dyspnea and fatigue that result in a decreased quality of life, which has not drastically improved over the past decades despite advances in therapies. The assessment of exercise capacity can provide information regarding patient diagnosis and prognosis, while doubling as a potential future therapy. clinically, there is acceptance that exercise is safe in hf and can have a positive impact on morbidity and quality of life, although evidence for improvement in mortality is still lacking. specific prescriptions for exercise training have not been developed because many variables and confounding factors have prevented research trials from demonstrating an ideal regimen. Physicians are becoming more aware of the indices and goals for hf patients in exercise testing and therapy to provide comprehensive cardiac care. it is further postulated that a combination of exercise training and pharmacologic therapy may eventually provide the most benefits to those suffering from hf.

Bioethics In Neurospinal Patient Care

2018 ◽  
Vol 1 (2) ◽  
pp. 1
Author(s):  
Andi Asadul Islam
Keyword(s):  
Time Frame ◽  
Hippocratic Oath ◽  
Moral Vision ◽  
Human Identity ◽  
The Past ◽  
Harvey Cushing ◽  
Sharp Focus ◽  
Realistic Approach ◽  
Cord Injury

Neurosurgery is among the newest of surgical disciplines, appearing in its modern incarnation at the dawn of twentieth century with the work of Harvey Cushing and contemporaries. Neurosurgical ethics involves challenges of manipulating anatomical locus of human identity and concerns of surgeons and patients who find themselves bound together in that venture.In recent years, neurosurgery ethics has taken on greater relevance as changes in society and technology have brought novel questions into sharp focus. Change of expanded armamentarium of techniques for interfacing with the human brain and spine— demand that we use philosophical reasoning to assess merits of technical innovations.Bioethics can be defined as systematic study of moral challenges in medicine, including moral vision, decisions, conduct, and policies related to medicine. Every surgeon should still take the Hippocratic Oath seriously and consider it a basic guide to follow good medical ethics in medical practice. It is simple and embodies three of the four modern bioethics principles – Respecting autonomy, beneficence, nonmaleficence, and justice.Spinal cord injury (SCI) is a devastating condition often affecting young and healthy individuals around the world. Currently, scientists are pressured on many fronts to develop an all-encompassing “cure” for paralysis. While scientific understanding of central nervous system (CNS) regeneration has advanced greatly in the past years, there are still many unknowns with regard to inducing successful regeneration. A more realistic approach is required if we are interested in improving the quality of life of a large proportion of the paralyzed population in a more expedient time frame.

Menopausal hormone therapy and uterine cancer: the acceptability of the tandem

GYNECOLOGY ◽  
2018 ◽  
Vol 20 (6) ◽  
pp. 42-47
Author(s):  
O V Yakushevskaya ◽  
S V Yureneva ◽  
A E Protasova ◽  
G N Khabas ◽  
M R Dumanovskaya
Keyword(s):  
Hormone Therapy ◽  
Uterine Cancer ◽  
Menopausal Hormone Therapy ◽  
Medical Rehabilitation ◽  
Cytostatic Treatment ◽  
Systematic Analysis ◽  
Strict Adherence ◽  
Patient Profile ◽  
The Past

The aim of the work is to conduct a systematic analysis of the available research results on the possibility of using menopausal hormone therapy (MHT) in patients who successfully completed the treatment of endometrial cancer (EC). Materials and methods. The review includes data from foreign articles published in PubMed and Medline, and domestic works published on elibrary.ru over the past 40 years. Results. The results obtained allow us to consider MHT as an independent method of medical rehabilitation for women who have undergone EC. A clear patient profile should be established, allowing the use of this method, with strict adherence to health monitoring. Conclusion Patients who have successfully completed the treatment of EC require the creation of special rehabilitation conditions in the interests of maintaining health and quality of life and should be under the close attention of the doctor. Argumented approaches to the appointment of MHT in such patients will avoid complications associated with estrogen deficiency after surgery, radiation with or without systemic (cytostatic) treatment methods.

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