Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 9 de 9
Filtrar
Mais filtros

Base de dados
País/Região como assunto
Tipo de documento
Assunto da revista
País de afiliação
Intervalo de ano de publicação
1.
Nature ; 588(7837): 272-276, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33239782

RESUMO

Mesozoic birds display considerable diversity in size, flight adaptations and feather organization1-4, but exhibit relatively conserved patterns of beak shape and development5-7. Although Neornithine (that is, crown group) birds also exhibit constraint on facial development8,9, they have comparatively diverse beak morphologies associated with a range of feeding and behavioural ecologies, in contrast to Mesozoic birds. Here we describe a crow-sized stem bird, Falcatakely forsterae gen. et sp. nov., from the Late Cretaceous epoch of Madagascar that possesses a long and deep rostrum, an expression of beak morphology that was previously unknown among Mesozoic birds and is superficially similar to that of a variety of crown-group birds (for example, toucans). The rostrum of Falcatakely is composed of an expansive edentulous maxilla and a small tooth-bearing premaxilla. Morphometric analyses of individual bony elements and three-dimensional rostrum shape reveal the development of a neornithine-like facial anatomy despite the retention of a maxilla-premaxilla organization that is similar to that of nonavialan theropods. The patterning and increased height of the rostrum in Falcatakely reveals a degree of developmental lability and increased morphological disparity that was previously unknown in early branching avialans. Expression of this phenotype (and presumed ecology) in a stem bird underscores that consolidation to the neornithine-like, premaxilla-dominated rostrum was not an evolutionary prerequisite for beak enlargement.


Assuntos
Bico/anatomia & histologia , Aves/anatomia & histologia , Fósseis , Animais , Evolução Biológica , Aves/classificação , Madagáscar , Filogenia
2.
Nature ; 581(7809): 421-427, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32461642

RESUMO

The fossil record of mammaliaforms (mammals and their closest relatives) of the Mesozoic era from the southern supercontinent Gondwana is far less extensive than that from its northern counterpart, Laurasia1,2. Among Mesozoic mammaliaforms, Gondwanatheria is one of the most poorly known clades, previously represented by only a single cranium and isolated jaws and teeth1-5. As a result, the anatomy, palaeobiology and phylogenetic relationships of gondwanatherians remain unclear. Here we report the discovery of an articulated and very well-preserved skeleton of a gondwanatherian of the latest age (72.1-66 million years ago) of the Cretaceous period from Madagascar that we assign to a new genus and species, Adalatherium hui. To our knowledge, the specimen is the most complete skeleton of a Gondwanan Mesozoic mammaliaform that has been found, and includes the only postcranial material and ascending ramus of the dentary known for any gondwanatherian. A phylogenetic analysis including the new taxon recovers Gondwanatheria as the sister group to Multituberculata. The skeleton, which represents one of the largest of the Gondwanan Mesozoic mammaliaforms, is particularly notable for exhibiting many unique features in combination with features that are convergent on those of therian mammals. This uniqueness is consistent with a lineage history for A. hui of isolation on Madagascar for more than 20 million years.


Assuntos
Fósseis , Ilhas , Mamíferos/anatomia & histologia , Mamíferos/classificação , Filogenia , Esqueleto/anatomia & histologia , Animais , Dentição , Madagáscar , Crânio/anatomia & histologia
3.
Nature ; 515(7528): 512-7, 2014 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-25383528

RESUMO

Previously known only from isolated teeth and lower jaw fragments recovered from the Cretaceous and Palaeogene of the Southern Hemisphere, the Gondwanatheria constitute the most poorly known of all major mammaliaform radiations. Here we report the discovery of the first skull material of a gondwanatherian, a complete and well-preserved cranium from Upper Cretaceous strata in Madagascar that we assign to a new genus and species. Phylogenetic analysis strongly supports its placement within Gondwanatheria, which are recognized as monophyletic and closely related to multituberculates, an evolutionarily successful clade of Mesozoic mammals known almost exclusively from the Northern Hemisphere. The new taxon is the largest known mammaliaform from the Mesozoic of Gondwana. Its craniofacial anatomy reveals that it was herbivorous, large-eyed and agile, with well-developed high-frequency hearing and a keen sense of smell. The cranium exhibits a mosaic of primitive and derived features, the disparity of which is extreme and probably reflective of a long evolutionary history in geographic isolation.


Assuntos
Fósseis , Mamíferos , Filogenia , Crânio/anatomia & histologia , Animais , Herbivoria , Mosaicismo , Especificidade da Espécie , Dente/anatomia & histologia
4.
Curr Sports Med Rep ; 18(1): 23-34, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30624332

RESUMO

The Ice Hockey Summit III provided updated scientific evidence on concussions in hockey to inform these five objectives: 1) describe sport-related concussion (SRC) epidemiology, 2) classify prevention strategies, 3) define objective, diagnostic tests, 4) identify treatment, and 5) integrate science and clinical care into prioritized action plans and policy. Our action plan evolved from 40 scientific presentations. The 155 attendees (physicians, athletic trainers, physical therapists, nurses, neuropsychologists, scientists, engineers, coaches, and officials) voted to prioritize these action items in the final Summit session. 1) Establish a national and international hockey data base for SRC at all levels, 2) eliminate body checking in Bantam youth hockey games, 3) expand a behavior modification program (Fair Play) to all youth hockey levels, 4) enforce game ejection penalties for fighting in Junior A and professional hockey leagues, 5) establish objective tests to diagnose concussion at point of care (POC), and 6) mandate baseline testing to improve concussion diagnosis for all age groups. Expedient implementation of the Summit III prioritized action items is necessary to reduce the risk, severity, and consequences of concussion in the sport of ice hockey.


Assuntos
Traumatismos em Atletas/epidemiologia , Traumatismos em Atletas/prevenção & controle , Concussão Encefálica/epidemiologia , Concussão Encefálica/prevenção & controle , Hóquei/lesões , Traumatismos em Atletas/diagnóstico , Traumatismos em Atletas/terapia , Concussão Encefálica/diagnóstico , Concussão Encefálica/terapia , Bases de Dados Factuais , Humanos , Medicina Esportiva/normas , Esportes Juvenis/normas
5.
Clin J Sport Med ; 27(5): 503-509, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28079758

RESUMO

OBJECTIVE: This review provides an update on sport-related concussion (SRC) in ice hockey and makes a case for changes in clinical concussion evaluation. Standard practice should require that concussions be objectively diagnosed and provide quantitative measures of the concussion injury that will serve as a platform for future evidence-based treatment. METHODS: The literature was surveyed to address several concussion-related topics: research in ice hockey-related head trauma, current subjective diagnosis, promising components of an objective diagnosis, and current and potential treatments. MAIN RESULTS: Sport-related head trauma has marked physiologic, pathologic, and psychological consequences for athletes. Although animal models have been used to simulate head trauma for pharmacologic testing, the current diagnosis and subsequent treatment in athletes still rely on an athlete's motivation to report or deny symptoms. Bias-free, objective diagnostic measures are needed to guide quantification of concussion severity and assessment of treatment effects. Most of the knowledge and management guidelines of concussion in ice hockey are generalizable to other contact sports. CONCLUSIONS: There is a need for an objective diagnosis of SRC that will quantify severity, establish a prognosis, and provide effective evidence-based treatment. Potential methods to improve concussion diagnosis by health care providers include a standardized concussion survey, the King-Devick test, a quantified electroencephalogram, and blood analysis for brain cell-specific biomarkers.


Assuntos
Concussão Encefálica/diagnóstico , Concussão Encefálica/terapia , Hóquei/lesões , Medicina Esportiva/normas , Atletas , Traumatismos Craniocerebrais/diagnóstico , Traumatismos Craniocerebrais/terapia , Humanos , Prognóstico
6.
Naturwissenschaften ; 97(4): 365-77, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20130827

RESUMO

Extant species of the supraordinal mammal clade Euarchonta belong to the orders Primates, Scandentia, or Dermoptera. The fossil record of euarchontans suggests that they underwent their initial radiation during the Paleocene (65-55 million years ago) in North America, Eurasia, and Africa. The time and place of origin is poorly resolved due to lack of definitive fossils of euarchontan stem taxa. We describe a fragmentary humerus and two fragmentary ulnae from the latest Cretaceous of India that bear significantly on this issue. The fossils are tentatively referred to Deccanolestes cf. hislopi due to their small size and the fact that Deccanolestes is the only eutherian dental taxon to have been recovered from the same locality. The new fossils are used to evaluate the existing behavioral hypothesis that Deccanolestes was arboreal, and the competing phylogenetic hypotheses that Deccanolestes is a stem eutherian versus a stem euarchontan. The humerus resembles those of euarchontans in possessing a laterally keeled ulnar trochlea, a distinct zona conoidea, and a spherical capitulum. These features also suggest an arboreal lifestyle. The ulnar morphology is consistent with that of the humerus in reflecting an arboreal/scansorial animal. Detailed quantitative comparisons indicate that, despite morphological correlates to euarchontan-like arboreality, the humerus of Deccanolestes is morphologically intermediate between those of Cretaceous "condylarthran" mammals and definitive Cenozoic euarchontans. Additionally, humeri attributed to adapisoriculids are morphologically intermediate between those of Deccanolestes and definitive euarchontans. If adapisoriculids are euarchontans, as recently proposed, our results suggest that Deccanolestes is more basal. The tentative identification of Deccanolestes as a basal stem euarchontan suggests that (1) Placentalia began to diversify and Euarchonta originated before the Cretaceous-Tertiary boundary and (2) the Indian subcontinent, Eurasia, and Africa are more likely places of origin for Euarchonta than is North America.


Assuntos
Mamíferos/anatomia & histologia , Animais , Osso e Ossos/anatomia & histologia , Feminino , Membro Anterior/anatomia & histologia , Fósseis , Úmero/anatomia & histologia , Índia , Mamíferos/classificação , Mamíferos/genética , Dente Molar/anatomia & histologia , Paleontologia , Filogenia , Placenta/anatomia & histologia , Gravidez , Primatas/anatomia & histologia
7.
Sci Am ; 296(2): 32-9, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17367020

RESUMO

Large meat-eating dinosaur Majungatholusatopus (above) met an untimely end some 70 million years ago in what is now northwestern Madagascar (opposite page, top]. Members of the authors' team carefully excavated the remains, including a jaw with serrated teeth used to slice through flesh (right), and packed them in plaster for transport to the U.S. (opposite page, bottom), where the researchers studied the fossils in detail for clues to the cause of death.


Assuntos
Dinossauros , Animais , Dinossauros/anatomia & histologia , Desastres , Fósseis , Fenômenos Geológicos , Geologia , Madagáscar , Comportamento Predatório
8.
J Dent Educ ; 74(3): 289-96, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20203329

RESUMO

In this article, we report on the evolution of a series of dental outreach missions sponsored by Stony Brook University to remote areas of Madagascar over a nine-year period. The project evolved from one dental resident performing only dental extractions in 1999 to a team comprised of two dentists, six third-year dental students, and two dental assistants performing dental restorations, extractions, and endodontic procedures using digital radiographic equipment in 2008. The ability during the latest mission to utilize digital radiography in remote areas lacking running water, electricity, and dental facilities significantly enhanced the range and efficacy of dental procedures. This long-term project offered senior dental students and residents from Stony Brook University's School of Dental Medicine an educationally valuable opportunity to engage in international dental outreach and to make a significant contribution to the improvement of oral health in the underserved rural communities of Madagascar.


Assuntos
Assistência Odontológica , Missões Médicas , Altruísmo , Assistência Odontológica/organização & administração , Equipamentos Odontológicos , Educação em Odontologia , Educação em Saúde Bucal , Humanos , Internato e Residência , Madagáscar , Missões Médicas/organização & administração , Área Carente de Assistência Médica , Preceptoria , Radiografia Dentária Digital , Saúde da População Rural , Faculdades de Odontologia , Estudantes de Odontologia , Tecnologia Odontológica
9.
Nature ; 422(6931): 515-8, 2003 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-12673249

RESUMO

Many lines of evidence have been brought to bear on the question of theropod feeding ecology, including functional and physiological considerations, morphological constraints, taphonomic associations, and telling--although rare--indications of direct ingestion. Tooth marks of theropods, although rarely described and generally left unassigned to a particular taxon, can provide unique clues into predator-prey interaction, and can also yield insights into the extent of carcass utilization. Here we describe a sample of tooth-marked dinosaur bone recovered from three well-documented localities in the Upper Cretaceous Maevarano Formation of Madagascar that provides insights into the feeding ecology of the abelisaurid theropod Majungatholus atopus. Intensely tooth-marked elements from multiple individuals show that Majungatholus defleshed dinosaur carcasses. Furthermore, Majungatholus clearly fed upon the remains of not only sauropods, but also conspecifics, and thus was a cannibal. Cannibalism is a common ecological strategy among extant carnivores, but until now the evidence in relation to carnivorous dinosaurs has been sparse and anecdotal.


Assuntos
Canibalismo , Dieta , Dinossauros/fisiologia , Fósseis , Animais , Osso e Ossos , Dinossauros/classificação , Madagáscar , Dente/fisiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA