RESUMO
Pulmonary infections caused by Bordetella pertussis used to be the prime cause of infant mortality in the pre-vaccine era and mouse models of pertussis pneumonia served in characterization of B. pertussis virulence mechanisms. However, the biologically most relevant catarrhal disease stage and B. pertussis transmission has not been adequately reproduced in adult mice due to limited proliferation of the human-adapted pathogen on murine nasopharyngeal mucosa. We used immunodeficient C57BL/6J MyD88 KO mice to achieve B. pertussis proliferation to human-like high counts of 108 viable bacteria per nasal cavity to elicit rhinosinusitis accompanied by robust shedding and transmission of B. pertussis bacteria to adult co-housed MyD88 KO mice. Experiments with a comprehensive set of B. pertussis mutants revealed that pertussis toxin, adenylate cyclase toxin-hemolysin, the T3SS effector BteA/BopC and several other known virulence factors were dispensable for nasal cavity infection and B. pertussis transmission in the immunocompromised MyD88 KO mice. In contrast, mutants lacking the filamentous hemagglutinin (FhaB) or fimbriae (Fim) adhesins infected the nasal cavity poorly, shed at low levels and failed to productively infect co-housed MyD88 KO or C57BL/6J mice. FhaB and fimbriae thus appear to play a critical role in B. pertussis transmission. The here-described novel murine model of B. pertussis-induced nasal catarrh opens the way to genetic dissection of host mechanisms involved in B. pertussis shedding and to validation of key bacterial transmission factors that ought to be targeted by future pertussis vaccines.
Assuntos
Adesinas Bacterianas , Bordetella pertussis , Coqueluche , Toxina Adenilato Ciclase , Adesinas Bacterianas/metabolismo , Animais , Bordetella pertussis/genética , Modelos Animais de Doenças , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Fator 88 de Diferenciação Mieloide , Cavidade Nasal/microbiologia , Vacina contra Coqueluche , Fatores de Virulência de Bordetella/genética , Coqueluche/transmissãoRESUMO
The objective of this article is to describe and classify usual interstitial pneumonia (UIP) changes according to their relevance in the pathology of the idiopathic pulmonary fibrosis (IPF) process. In a cohort of 50 patients (25â, 25â) with UIP findings, the percentage ratio between fibrotic and preserved parts of the lungs was quantified. Three quantitative stages of fibrotic involvement of the lung parenchyma and concomitant changes were defined. These are initial (≤20%), advanced (21-40%), and diffuse (≥41%) fibrosis of the lungs. Histologically, temporal heterogeneity is predominant with thickened alveolar septa, interstitial fibrosis, and the presence of fibroblastic foci up to mature diffuse fibrosis with honeycomb changes. The finding is accompanied by variably mature lymphocytic inflammation, presence of macrophages, emphysema, bronchioloectasia of the alveoli, bronchiectasis, bronchial muscle wall hypertrophy, hypertrophy of the vessel walls, alveolar mucosa, focal haemorrhage, and hyalinization of the lungs. Pneumocyte hyperplasia, occasionally atypical in appearance with hobnail changes, as well as squamous metaplasia are observed. In the methodically quantified stages of fibrous involvement, 14 subjects were classified (6â, 8â) into the stage of initial fibrosis, 21 subjects (11â; 10â) into the stage of advanced fibrosis, and 15 subjects (8â; 7â) into the stage of diffuse fibrosis.
Assuntos
Fibrose Pulmonar Idiopática , Humanos , Fibrose Pulmonar Idiopática/patologia , Pulmão/patologia , Biópsia , Fibrose , Hipertrofia/patologiaRESUMO
OBJECTIVES: The aim of the study was to evaluate pulmonary sequestration (PS). We report on location, blood supply, histology, clinical manifestation, and surgical treatment of PS, as well as on postoperative course in patients with PS. BACKGROUND: PS is a rare congenital defect of the lower respiratory tract, it represents locus minoris resistentiae of the body. Occasionally, PS is diagnosed for the first time in adulthood. METHODS: We evaluated 7 cases of PS treated at the Centre of Thoracic Surgery in Vysné Hágy, Slovakia, between years 2013 and 2020. RESULTS: Four of our seven patients were asymptomatic; the PS was found incidentally upon chest imaging. Three patients had recurrent bronchopneumonia related specifically to the intralobar type of sequestration. The most significant complication, observed in a singular patient, was a life-threatening episode of haemoptysis, requiring urgent surgical intervention. In the other 6 cases, the sequestra were surgically resected during the period when they were asymptomatic. and their sputum was confirmed negative upon microbiological examination. Anatomical resection of the affected pulmonary lobe by thoracotomy was the most common type of operation performed (4 cases, n = 7). There was no surgical mortality. CONCLUSION: To prevent complications, it is crucial to perform surgical treatment for pulmonary sequestration in patients who have sufficient functional capacity (Tab. 2, Fig. 4, Ref. 30). Text in PDF www.elis.sk Keywords: pulmonary sequestration, anatomic lobectomy, haemoptysis.
Assuntos
Sequestro Broncopulmonar , Humanos , Sequestro Broncopulmonar/diagnóstico por imagem , Sequestro Broncopulmonar/cirurgia , Hemoptise/cirurgia , Tomografia Computadorizada por Raios X , Pulmão/cirurgia , Pulmão/patologia , ToracotomiaRESUMO
Breast cancer metastases are the main reason for women´s highest cancer mortality. Even though tumor cell dissemination via circulating tumor cells (CTC) released from the primary site is a very ineffective process, distant metastases appear in 46% of triple-negative breast cancer (TNBC) patients corresponding to the disease aggressiveness. Laboratory models for functional testing which mimic the spread of metastatic cells are needed for efficient investigation of the underlying mechanisms and therapeutic intervention. Here, we describe novel isogenic variants LMC3 and CTC3 of human TNBC cell line MDA-MB-231 that were derived by repeated injection of tumor cells into the tail vein of immunodeficient mice and subsequent selection of metastatic cells from lung metastases. These variants have increased migration potential, altered expression profiles, and elevated tumorigenic potential. Moreover, cell line CTC3 readily produces metastases in the lungs and bone marrow and detectable viable circulating tumor cells in the blood. This model enables rapid and cost-efficient strategies for biomarker exploration and novel intervention approaches to limit the CTC presence in the blood and hence tumor dissemination.
Assuntos
Neoplasias Pulmonares , Células Neoplásicas Circulantes , Neoplasias de Mama Triplo Negativas , Humanos , Feminino , Camundongos , Animais , Células Neoplásicas Circulantes/metabolismo , Neoplasias de Mama Triplo Negativas/genética , Neoplasias de Mama Triplo Negativas/patologia , Linhagem Celular Tumoral , Neoplasias Pulmonares/secundário , Biomarcadores , Metástase NeoplásicaRESUMO
Cells of pre-implantation embryos are equipped with many morphological and functional systems through which they can synthesize specific proteins and effectively ensure the protection of early embryonic development. Here we present evidence for the existence of these systems in morphologically normal and abnormal bovine blastocyst stage embryos in vivo at the ultrastructural and actin cytoskeleton levels. The appearance of organelles in the trophectoderm (TE) and inner cell mass (ICM) cells, responsible for their synthetic activities and their role in the development of early bovine embryos are described. We point out the importance of endocytic processes and the participation of extracellular vesicles in the formation of intercellular contacts and homeostasis of the embryo microenvironment. Several changes in the ultrastructural morphology of embryos produced by different methods (ICSI, parthenogenetic AC/DC electrical activation, IVF with separated sperm) and freezing/thawed embryos are described. We also show alterations occurred in the organelles after viral contamination of embryos with BHV-1 and BVDV viruses, and in embryos from over-conditioned cows. Recorded changes in organelles and appearance of cellular autophagic structures (vesicles, multivesicular bodies and autophagolysosomes) may negatively affect embryo metabolism and lead to the emergence of pathological processes in TE and ICM cells of preimplantation embryos.
Assuntos
Desenvolvimento Embrionário , Sêmen , Gravidez , Feminino , Masculino , Animais , Bovinos , Desenvolvimento Embrionário/fisiologia , Blastocisto/fisiologia , Blastocisto/ultraestruturaRESUMO
The authors present two cases of borderline ovarian tumours with microinvasion in bitches with variable clinical significance. The first case documents a four-year-old female Weimaraner diagnosed with a tumour on the right ovary during a veterinary check-up, using ultrasound (USG) examination, which was then surgically removed. Histological examination revealed a clear cell borderline tumour of the ovary with microinvasion. The second case is represented by a necropsy sample from a 52-month-old female German Shepherd who died a day before the planned hysterectomy due to undertreated pyometra. During necropsy, a developed bilateral ovarian tumour was found. An additional histological examination revealed a serous borderline tumour with microinvasion of both ovaries. This paper discusses the histopathological and clinical aspects involved in the prognosis of borderline ovarian tumours in bitches. This concerns the possibility of a change for a more aggressive behaviour of these tumours and their immunohistochemical profile, then the risk of implant metastases and, finally, the time point of diagnosis, intervention, and therapy. Even histologically verified well-differentiated forms of borderline ovarian tumours with microinvasion in bitches can show the variable clinical significance and, therefore, in similar cases, only a good or only a bad prognosis of the disease should not be expected.
RESUMO
Suicides are one of the topics discussed around the world. This problem receives large space in scientific and professional literature, in order to eliminate its occurrence. Mechanisms of suicides are determined by whole spectrum of reasons determined by/depending on physical and psychological health. The objective of this work is to document the differences in mechanisms and realization of suicides by mentally sick people. Ten cases of suicides are reported in the article: three of which in people with a history of depression of the victim noted by family members, one with treated depression, three with anxiety-depressive disorder and three schizophrenic patients cases. There are five men and five women. Four of these women overdosed themselves by medicaments and one jumped out of a window. Two men shot themselves, two hanged themselves and one jumped out of a window. Persons without anamnestically proven psychiatric diseases end their lives mostly because of inconclusive situation or as a result of balancing their whole life (usually with good plan and preparation of the act). Persons with treatment of depression or anxiety-depressive disorder kill themselves mostly after several "unsuccessful" attempts. In case of victims with schizophrenia suicides follow a hardly predictable sequence of actions which sometimes do not seem to have any logic. Differences have been found between victims with and without mental disorders in ways of realization of suicides. Psychological predispositions in mood changes, long-term sadness and threatening suicide should be recognized by family members. Prevention of suicides in cases of people with a history of mental disorders is based on medical treatment and cooperation between the client and family members and a psychiatrist (Ref. 30). Keywords: forensic medicine, mental disorders, prevention, psychiatry, risk factors, suicides.
Assuntos
Transtornos Mentais , Esquizofrenia , Suicídio , Masculino , Humanos , Feminino , Suicídio/psicologia , Transtornos Mentais/epidemiologia , Transtornos Mentais/psicologia , Esquizofrenia/epidemiologia , Fatores de Risco , Suscetibilidade a DoençasRESUMO
Celiac disease (CD) is a disorder that affects both children and adults. Over the few last decades, several new atypical cases have been identified through improved diagnostic tools. On the other hand, the onset of CD at a later age, including atypical CD forms whose clinical picture overlaps with other autoimmune diseases, shows that currently there are several unknown gene mutations, which could be responsible for the disease development. Non-celiac gluten sensitivity (NCGS) is entity included by the ingestion of gluten leading to intestinal, or extraintestinal symptoms that improve once the gluten is removed from the nutrition. In this article relationships between genetically modified rodent animals with previously unknown multiple organ changes and CD, respectively NCGS are reviewed. Relationships between the small bowel histological changes and other organs pathology are discussed. Results of research document that changes have similar genetic background and can develop to serious autoimmune systematic diseases, including small bowel inflammation resembling atypical CD or NCGS. These may have extra-intestinal symptomatology but without a clear explanation of causes and differences in their manifestations. Research on animal models helps to discover links between several disorders associated with gastrointestinal damage. New methods based on individual gene mutations can help in atypical adult CD and NCGS recognitions in the future.
Assuntos
Doença Celíaca , Roedores , Animais , Doença Celíaca/genética , Glutens , Modelos AnimaisRESUMO
Ovarian teratomas are rare neoplasms in female dogs, and they are characterised by the proliferation of tissues of embryonic origin. Most teratomas are benign, but a histological diagnosis is important for clinicians. The objective of this article is to describe a benign ovarian teratoma in a dog, which was found on the street and was appearing like pregnant. A veterinary inspection by palpation documented an enlarged abdomen with a mass of tough matter located on the right side in the abdominal-pelvic part. An ultrasound examination presumed neoplastic mass in region of ovary. A bilateral ovariohysterectomy was performed and the subsequent histological evaluation revealed a benign ovarian teratoma with a histochemically and immunohistochemically verified nervous tissue. After one year, no distant metastases were found and the dog was recognised as being clinically healthy without problems. On the basis of the ultrasonography diagnostics and histopathological analyses, we have demonstrated the occurrence of a benign ovarian teratoma in a dog.
RESUMO
Osteohistological data are commonly used to study the life history of extant and extinct tetrapods. While recent advances have permitted detailed reconstructions of growth patterns, physiology and other features using these data, they are most commonly used in assessments of ontogenetic stage and relative growth in extinct animals. These methods have seen widespread adoption in recent years, rapidly becoming a common component of the taxonomic description of new fossil taxa, but are often applied without close consideration of the sources of variation present or the dimensional scaling relationships that exist among different osteohistological measurements. Here, we use a combination of theoretical models and empirical data from a range of extant and extinct tetrapods to review sources of variability in common osteohistological measurements, their dimensional scaling relationships and the resulting interpretations that can be made from those data. In particular, we provide recommendations on the usage and interpretation of growth mark spacing/zonal thickness data, when these are likely to be unreliable, and under what conditions they can provide useful inferences for studies of growth and life history.
Assuntos
Fósseis , AnimaisRESUMO
Alcohol is a well-known, socially tolerated drug. Its harmfulness to human health, including its associated negative impact on the family of alcoholics, is well known. It is an interdisciplinary problem, whose solution requires financial contributions, society support, the involvement of a wider group of experts and finally also an active approach on young people and adults to this problem. The work is based on six lethal alcohol intoxication cases. The first case is devoted to a woman who dies in alcohol intoxication in the casino. The second case involves a man who died near the pond in alcohol intoxication. The third describes the course of the trip associated with drinking to the alcohol poisoning stage and the subsequent death of a man in a car. The fourth case is based on continual full-day drinking to the alcohol poisoning stage and subsequent death of a man. The fifth case describes the course of a riotous celebration, which ends with the death of an alcohol poisoned man. The last sixth case documents an alcohol poisoned man, which in combination with the ingestion of cannabinoids died on a bus station. The causes and reasons leading to such tragic events are discussed here. Attention is drawn to the dangers arising from the sudden drinking of occasional consumers and also to the dangers of the sudden drinking of persons who consume alcohol in excessive doses for a long time. Furthermore, the prevention of the use of alcoholic beverages by children and young people, including the prevention of alcoholism are discussed. Educational programs are proposed to create a remedial measure for de-tabooing this issue and format the attitudes of children, adolescents and adults to drinking alcohol, with the expectation of a reduction in deaths from alcohol intoxication in the future.
Assuntos
Intoxicação Alcoólica , Alcoolismo , Adolescente , Adulto , Consumo de Bebidas Alcoólicas/efeitos adversos , Consumo de Bebidas Alcoólicas/prevenção & controle , Intoxicação Alcoólica/complicações , Intoxicação Alcoólica/prevenção & controle , Alcoolismo/complicações , Criança , Etanol , Feminino , Humanos , Estudos Longitudinais , MasculinoRESUMO
The independent evolution of gigantism among dinosaurs has been a topic of long-standing interest, but it remains unclear if gigantic theropods, the largest bipeds in the fossil record, all achieved massive sizes in the same manner, or through different strategies. We perform multi-element histological analyses on a phylogenetically broad dataset sampled from eight theropod families, with a focus on gigantic tyrannosaurids and carcharodontosaurids, to reconstruct the growth strategies of these lineages and test if particular bones consistently preserve the most complete growth record. We find that in skeletally mature gigantic theropods, weight-bearing bones consistently preserve extensive growth records, whereas non-weight-bearing bones are remodelled and less useful for growth reconstruction, contrary to the pattern observed in smaller theropods and some other dinosaur clades. We find a heterochronic pattern of growth fitting an acceleration model in tyrannosaurids, with allosauroid carcharodontosaurids better fitting a model of hypermorphosis. These divergent growth patterns appear phylogenetically constrained, representing extreme versions of the growth patterns present in smaller coelurosaurs and allosauroids, respectively. This provides the first evidence of a lack of strong mechanistic or physiological constraints on size evolution in the largest bipeds in the fossil record and evidence of one of the longest-living individual dinosaurs ever documented.
Assuntos
Evolução Biológica , Tamanho Corporal , Dinossauros , Animais , Osso e Ossos/fisiologia , Fósseis , FilogeniaRESUMO
INTRODUCTION: Neuroblastoma ranks third among pediatric malignancies. CASE REPORT: The case of a 3-year-old child is presented, who suddenly had frequent, unproductive, emetic cough; fever; and weight loss. Lung X-ray showed an opacity situated in the posterior superior mediastinum. Thoracic ultrasound revealed a slightly inhomogeneous, hypoechoic mass located in the posterior superior mediastinum. Computed tomography evidenced a tumor mass with homogeneous appearance in the costo-vertebral groove. Histological examination confirmed the diagnosis of ganglioneuroblastoma. CONCLUSION: Although history and clinical examination provided few elements, diagnosis was made based on imaging and histopathological examination.
Assuntos
Gânglios Simpáticos/patologia , Ganglioneuroblastoma/diagnóstico , Neoplasias do Sistema Nervoso Periférico/diagnóstico , Pré-Escolar , Ganglioneuroblastoma/patologia , Ganglioneuroblastoma/cirurgia , Humanos , Masculino , Neoplasias do Sistema Nervoso Periférico/patologia , Neoplasias do Sistema Nervoso Periférico/cirurgiaRESUMO
BACKGROUND: New treatments in coeliac disease are being vigorously pursued to either replace or facilitate the difficult-tofollow gluten-free diet. DESIGN: The present review intends to summarise the challenges in gluten-free diet adherence during the transitional period, as reflected in the last Prague consensus, published in 2016. RESULTS: The honourable panel members recommended that dietary adherence and the consequences of nonadherence represent key components for discussion in the transitional period setting. CONCLUSIONS: There are numerous difficulties in adhering to gluten withdrawal, but the transition period from adolescence to young adulthood is considered a fragile and high-risk period for intentional and unintentional gluten intake.
Assuntos
Doença Celíaca/dietoterapia , Dieta Livre de Glúten , Cooperação do Paciente , Adolescente , Fatores Etários , Consenso , Humanos , Guias de Prática Clínica como Assunto , Adulto JovemRESUMO
We report three lethal cases of bleeding to the upper gastrointestinal tract as immediate cause of death. The first two cases are in connection with homelessness. First is a male who was found dead in a railway station, seated on a bench with dried blood beneath him. The second is a male who was found lifeless in a wooden shelter, where upon the good will of the landowners, he lived. At autopsy, gastroduodenal ulcer disease with a damaged blood vessel at the ulcer base was found in both. The cause of death was stated as hypovolemic shock, arising from loss of blood from bleeding gastroduodenal ulcer disease. The third case shows a man with liver cirrhosis, who was transported to hospital when his health deteriorated, where he died with blood vomiting. The case was closed as hypovolemic shock from loss of blood and was ascribed to haemorrhagic diathesis and chronic liver insufficiency, and excluded haemoptysis as the cause of the bleeding. The paper draws attention to the risk of mortality in patients with gastroduodenal ulcer disease, with irregular food intake, including alcohol abuse. The cases demonstrate the importance of medical care for patients who are prone to gastric ulcers, or to patients who have been diagnosed and/or treated for gastroduodenal ulcer disease, as the severe risk of ulcer bleeding, leading eventually to ulcer perforation. Our case reports may inform ambulance crews responding to at-risk individuals, such as homeless people, to the immediate threat of possible gastroduodenal ulcer disease with ulcer bleeding, or ulcer perforation.Key words: bleeding - death - gastric ulcer - gastroduodenal ulcer disease - nutrition - preventive medicine.
Assuntos
Úlcera Péptica Hemorrágica/patologia , Úlcera Péptica/patologia , Idoso , Autopsia , Evolução Fatal , Humanos , Cirrose Hepática Alcoólica/complicações , Masculino , Pessoa de Meia-Idade , Úlcera Péptica/complicações , Úlcera Péptica Hemorrágica/etiologia , Trato Gastrointestinal Superior/patologiaRESUMO
The bloodstain pattern analysis (BPA) is useful in the forensic medicine. In Czechoslovakian criminology is this method not commonly used. The objective of this work is to calculate the impact length, height and distance splashing of blood drops. The results are compared with the real values for specific cases. It is also compared to calculate the angle of incidence of blood drops, using sinα with a form using tgα. For this purposes we used two different character cases from practice with well-preserved condition and readable blood stains. Selected blood stains were documented in order to calculate the angle of incidence of blood drops and to calculateorigin splashes. For this drop of blood, the distance of impact of the drops of blood (x), the height of the sprayed blood drops (y) and the length of the flight path the drop of blood (l). The obtained data was retrospectively analysed for the two models. The first straight line is represented by the triangle (M1) and the other is the parabolic model (M2). The formulae were derived using the Euler substitution. The results show that the angle of incidence of the drop of blood can be calculated as sinα and the tgα. When applying, the triangle is appropriate to consider the application and sinα parabolic requires the calculation of the angle of incidence drops of blood tgα. Parabola is useful for the BPA. In Czechoslovakian should be providing workplace training seminars BPA primarily intended for forensic investigators.We recommend the use of this method during investigations, verification of acts in forensic practice.
Assuntos
Manchas de Sangue , Medicina Legal/métodos , HumanosRESUMO
Colorectal cancer (CRC) is one of the main causes of death of neoplasia. Demand for predictive and prognostic markers to reverse this trend is increasing. Long non-coding RNA HOTAIR (Homeobox Transcript Antisense Intergenic RNA) overexpression in tumors was previously associated with poor prognosis and higher mortality in different carcinomas. We analyzed HOTAIR expression levels in tumor and blood of incident sporadic CRC patients in relation to their overall survival with the aim to evaluate surrogate prognostic marker for CRC. Tissue donor group consisted of 73 CRC patients sampled for tumor and normal tissue. Blood donor group was represented by 84 CRC patients compared with 40 healthy controls. Patients were characterized for tumor-node-metastasis stage, tumor grade, microsatellite instability and tumor penetration by stromal cells. HOTAIR levels were assessed by real-time quantitative PCR. CRC patients had higher HOTAIR expression in blood than healthy controls (P = 0.0001), whereas there was no difference in HOTAIR levels between tumor and adjacent mucosa of CRC patients. HOTAIR levels positively correlated between blood and tumor (R = 0.43, P = 0.03). High HOTAIR levels in tumors were associated with higher mortality of patients [Cox's proportional hazard, hazard ratio = 4.4, 95% confidence interval: 1.0-19.2, P = 0.046]. The hazard ratio was even higher when blood HOTAIR levels were taken into account (hazard ratio = 5.9, 95% confidence interval: 1.3-26.1, P = 0.019). Upregulated HOTAIR relative expression in primary tumors and in blood of CRC patients is associated with unfavorable prognosis. Our data suggest that HOTAIR blood levels may serve as potential surrogate prognostic marker in sporadic CRC.
Assuntos
Biomarcadores Tumorais/genética , Neoplasias Colorretais/genética , RNA Longo não Codificante/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores Tumorais/sangue , Estudos de Casos e Controles , Colo/metabolismo , Neoplasias Colorretais/sangue , Neoplasias Colorretais/mortalidade , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Gradação de Tumores , Estadiamento de Neoplasias , Prognóstico , RNA Longo não Codificante/sangue , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Reto/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Taxa de SobrevidaRESUMO
Ecological divergence is thought to be coupled with evolutionary radiations, yet the strength of this coupling is unclear. When birds diversified ecologically has received much less attention than their hotly debated crown divergence time. Here, we quantify how accurately skeletal morphology can predict ecology in living and extinct birds, and show that the earliest known assemblage of birds (=pygostylians) from the Jehol Biota (≈125 Ma) was substantially impoverished ecologically. The Jehol avifauna has few representatives of highly preservable ecomorphs (e.g. aquatic forms) and a notable lack of ecomorphological overlap with the pterosaur assemblage (e.g. no large or aerially foraging pygostylians). Comparisons of the Jehol functional diversity with modern and subfossil avian assemblages show that taphonomic bias alone cannot explain the ecomorphological impoverishment. However, evolutionary simulations suggest that the constrained ecological diversity of the Early Cretaceous pygostylians is consistent with what is expected from a relatively young radiation. Regardless of the proximate biological explanation, the anomalously low functional diversity of the Jehol birds is evidence both for ecological vacancies in Cretaceous ecosystems, which were subsequently filled by the radiation of crown Aves, and for discordance between taxonomic richness and ecological diversity in the best-known Mesozoic ecosystem.
Assuntos
Aves/anatomia & histologia , Aves/fisiologia , Fósseis/anatomia & histologia , Animais , Evolução Biológica , Osso e Ossos/anatomia & histologia , Ecossistema , Comportamento AlimentarRESUMO
Interpreting key ecological parameters, such as diet, of extinct organisms without the benefit of direct observation or explicit fossil evidence poses a formidable challenge for paleobiological studies. To date, dietary categorizations of extinct taxa are largely generated by means of modern analogs; however, for many species the method is subject to considerable ambiguity. Here we present a refined approach for assessing trophic habits in fossil taxa and apply the method to coelurosaurian dinosaurs--a clade for which diet is particularly controversial. Our findings detect 21 morphological features that exhibit statistically significant correlations with extrinsic fossil evidence of coelurosaurian herbivory, such as stomach contents and a gastric mill. These traits represent quantitative, extrinsically founded proxies for identifying herbivorous ecomorphology in fossils and are robust despite uncertainty in phylogenetic relationships among major coelurosaurian subclades. The distribution of these features suggests that herbivory was widespread among coelurosaurians, with six major subclades displaying morphological evidence of the diet, and that contrary to previous thought, hypercarnivory was relatively rare and potentially secondarily derived. Given the potential for repeated, independent evolution of herbivory in Coelurosauria, we also test for repetitive patterns in the appearance of herbivorous traits within sublineages using rank concordance analysis. We find evidence for a common succession of increasing specialization to herbivory in the subclades Ornithomimosauria and Oviraptorosauria, perhaps underlain by intrinsic functional and/or developmental constraints, as well as evidence indicating that the early evolution of a beak in coelurosaurians correlates with an herbivorous diet.