Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 11 de 11
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Anat Rec (Hoboken) ; 307(4): 1366-1389, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36951279

RESUMO

Understanding the origins of the vertebrate brain is fundamental for uncovering evolutionary patterns in neuroanatomy. Regarding extinct species, the anatomy of the brain and other soft tissues housed in endocranial spaces can be approximated by casts of these cavities (endocasts). The neuroanatomical knowledge of Rhynchocephalia, a reptilian clade exceptionally diverse in the early Mesozoic, is restricted to the brain of its only living relative, Sphenodon punctatus, and unknown for fossil species. Here, we describe the endocast and the reptilian encephalization quotient (REQ) of the Triassic rhynchocephalian Clevosaurus brasiliensis and compare it with an ontogenetic series of S. punctatus. To better understand the informative potential of endocasts in Rhynchocephalia, we also examine the brain-endocast relationship in S. punctatus. We found that the brain occupies 30% of its cavity, but the latter recovers the general shape and length of the brain. The REQ of C. brasiliensis (0.27) is much lower than S. punctatus (0.84-1.16), with the tuatara being close to the mean for non-avian reptiles. The endocast of S. punctatus is dorsoventrally flexed and becomes more elongated throughout ontogeny. The endocast of C. brasiliensis is mostly unflexed and tubular, possibly representing a more plesiomorphic anatomy in relation to S. punctatus. Given the small size of C. brasiliensis, the main differences may result from allometric and heterochronic phenomena, consistent with suggestions that S. punctatus shows peramorphic anatomy compared to Mesozoic rhynchocephalians. Our results highlight a previously undocumented anatomical diversity among rhynchocephalians and provide a framework for future neuroanatomical comparisons among lepidosaurs.


Assuntos
Neuroanatomia , Répteis , Animais , Filogenia , Répteis/anatomia & histologia , Evolução Biológica , Encéfalo/anatomia & histologia , Fósseis , Crânio/anatomia & histologia
2.
Anat Rec (Hoboken) ; 2023 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-37779325

RESUMO

Four extant species of anhingids are found worldwide, all belonging to a single genus (Anhinga). However, the fossil record reveals a much greater diversity of this group in the past. The oldest known anhingids date back to the upper Oligocene period in Australia, but during the Miocene epoch in South America, they achieved their most remarkable diversity. This study describes newly discovered anhingid fossils from the Late Miocene period in South America. These fossils were extracted from the Acre conglomerate member, part of the Upper Miocene deposits in the southwestern Amazon region. The described fossils consist of two fragments of pelvic girdles, two femora, and two vertebrae belonging to a giant anhingid (Macranhinga sp.), as well as a vertebra from Anhinga minuta, the smallest of all darters. The examination of these fossils suggests the presence of potentially three distinct anhingid taxa within the same locality. The environment in which the conglomerate deposits were formed was ecologically complex. It is likely that these three species coexisted within the same ecosystem but avoided direct competition for food and reproductive sites by not fully exploiting their fundamental niche.

3.
Biology (Basel) ; 11(11)2022 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-36358337

RESUMO

Molecular information has been gathered from fossilized dental enamel, the best-preserved tissue of vertebrates. However, the association of morphological features with the possible mineral and organic information of this tissue is still poorly understood in the context of the emerging area of paleoproteomics. This study aims to compare the morphological features and chemical composition of dental enamel of extinct and extant terrestrial vertebrates of Crocodylia: Purussaurus sp. (extinct) and Melanosuchus niger (extant), and Rodentia: Neoepiblema sp. (extinct) and Hydrochoerus hydrochaeris (extant). To obtain structural and chemical data, superficial and internal enamel were analyzed by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (SEM-EDS). Organic, mineral, and water content were obtained using polarizing microscopy and microradiography on ground sections of four teeth, resulting in a higher organic volume than previously expected (up to 49%). It is observed that both modern and fossil tooth enamel exhibit the same major constituents: 36.7% Ca, 17.2% P, and 41% O, characteristic of hydroxyapatite. Additionally, 27 other elements were measured from superficial enamel by inductively coupled mass spectrometry (ICP-MS). Zinc was the most abundant microelement detected, followed by Pb, Fe, Mg, and Al. Morphological features observed include enamel rods in the rodent teeth, while incremental lines and semiprismatic enamel were observed in the alligator species. The fossil enamel was in an excellent state for microscopic analyses. Results show that all major dental enamel's physical, chemical, and morphological features are present both in extant and extinct fossil tooth enamel (>8.5 Ma) in both taxa.

4.
Rev Saude Publica ; 55: 46, 2021.
Artigo em Inglês, Português | MEDLINE | ID: mdl-34730746

RESUMO

OBJECTIVE: To investigate gender inequity in the scientific production of the University of Sao Paulo. METHODS: Members of the University of Sao Paulo faculty are the study population. The Web of Science repository was the source of the publication metrics. We selected the measures: total publications and citations, average of citations per year and item, H-index, and history of citations between 1950 and 2019. We used the name of the faculty member as a proxy to the gender identity. We use descriptive statistics to characterize the metrics. We evaluated the scissors effect by selecting faculty members with a high H-index. The historical series of citations was projected until 2100. We carry out analyses for the general population and working time subgroups: less than 10 years, 10 to 20 years, and 20 years or more. RESULTS: Of the 8,325 faculty members, we included 3,067 (36.8%). Among those included, 1,893 (61.7%) were male and 1,174 (38.28%) female. The male gender presented higher values in the publication metrics (average of articles: M = 67.0 versus F = 49.7; average of citations/year: M = 53.9 versus F = 35.9), and H-index (M = 14.5 versus F = 12.4). Among the 100 individuals with the highest H-index (≥ 37), 83% are male. The male curve grows faster in the historical series of citations, opening a difference between the groups whose separation is confirmed by the projection. DISCUSSION: Scientific production at the Universidade de São Paulo is subject to a gender bias. Two-thirds of the faculty are male, and hiring over the past few decades perpetuates this pattern. The large majority of high impact faculty members are male. CONCLUSION: Our analysis suggests that the Universidade de São Paulo will not overcome gender inequality in scientific production without substantive affirmative action. Development does not happen by chance but through choices that are affirmative, decisive, and long-term oriented.


Assuntos
Identidade de Gênero , Sexismo , Brasil , Docentes , Feminino , Humanos , Masculino
5.
iScience ; 24(3): 102180, 2021 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-33718832

RESUMO

[This corrects the article DOI: 10.1016/j.isci.2020.101834.].

6.
Rev. saúde pública (Online) ; 55: 1-12, 2021. tab, graf
Artigo em Inglês, Português | LILACS, BBO - Odontologia | ID: biblio-1347816

RESUMO

ABSTRACT OBJECTIVE To investigate gender inequity in the scientific production of the University of Sao Paulo. METHODS Members of the University of Sao Paulo faculty are the study population. The Web of Science repository was the source of the publication metrics. We selected the measures: total publications and citations, average of citations per year and item, H-index, and history of citations between 1950 and 2019. We used the name of the faculty member as a proxy to the gender identity. We use descriptive statistics to characterize the metrics. We evaluated the scissors effect by selecting faculty members with a high H-index. The historical series of citations was projected until 2100. We carry out analyses for the general population and working time subgroups: less than 10 years, 10 to 20 years, and 20 years or more. RESULTS Of the 8,325 faculty members, we included 3,067 (36.8%). Among those included, 1,893 (61.7%) were male and 1,174 (38.28%) female. The male gender presented higher values in the publication metrics (average of articles: M = 67.0 versus F = 49.7; average of citations/year: M = 53.9 versus F = 35.9), and H-index (M = 14.5 versus F = 12.4). Among the 100 individuals with the highest H-index (≥ 37), 83% are male. The male curve grows faster in the historical series of citations, opening a difference between the groups whose separation is confirmed by the projection. DISCUSSION Scientific production at the Universidade de São Paulo is subject to a gender bias. Two-thirds of the faculty are male, and hiring over the past few decades perpetuates this pattern. The large majority of high impact faculty members are male. CONCLUSION Our analysis suggests that the Universidade de São Paulo will not overcome gender inequality in scientific production without substantive affirmative action. Development does not happen by chance but through choices that are affirmative, decisive, and long-term oriented.


RESUMO OBJETIVO Investigar desigualdades de gênero na produção científica de docentes da Universidade de São Paulo. MÉTODOS A população consiste em professores(as) da Universidade de São Paulo. O repositório Web of Science foi a fonte das métricas de publicação. Selecionamos as medidas: total de publicações e citações, média de citações por ano e por item, índice H e histórico de citações entre 1950 e 2019. Usamos o nome do(a) docente como um proxy para a identidade de gênero. Usamos estatísticas descritivas para caracterizar as métricas. Avaliamos o efeito tesoura selecionando os(as) professores(as) com índice H alto. A série histórica de citações foi projetada até 2100. Realizamos análises para a população geral e subgrupos de tempo de trabalho: menos de 10 anos, de 10 a 20 anos e 20 anos ou mais. RESULTADOS Dos 8.325 docentes, incluímos 3.067 (36,8%). Dentre os incluídos, 1.893 (61,7%) eram professores e 1.174 (38,28%) professoras. O gênero masculino apresentou valores mais altos nas métricas de publicação (média de artigos: M = 67,0 versus F = 49,7; média de citações/ano: M = 53,9 versus F = 35,9) e índice H (M = 14,5 versus F = 12,4). Entre os 100 indivíduos com maior índice H (≥ 37), 83% são do gênero masculino. Na série histórica de citações, a curva masculina cresce mais rápido, abrindo uma diferença entre os grupos com afastamento confirmado pela projeção. DISCUSSÃO A produção científica na Universidade de São Paulo está sujeita a um viés de gênero. Dois terços do corpo docente são do gênero masculino, e as contratações das últimas décadas perpetuam esse padrão. A grande maioria dos membros com alto impacto no corpo docente é do sexo masculino. CONCLUSÃO Nossas análises sugerem que a Universidade de São Paulo não superará a desigualdade de gênero na produção científica sem uma ação afirmativa substancial. O desenvolvimento não acontece por acaso, mas por meio de escolhas afirmativas, decisivas e de longo prazo.


Assuntos
Humanos , Masculino , Feminino , Sexismo , Identidade de Gênero , Brasil , Docentes
7.
iScience ; 23(12): 101834, 2020 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-33305189

RESUMO

Blind snakes (Scolecophidia) are minute cryptic snakes that diverged at the base of the evolutionary radiation of modern snakes. They have a scant fossil record, which dates back to the Upper Paleocene-Lower Eocene (∼56 Ma); this late appearance conflicts with molecular evidence, which suggests a much older origin for the group (during the Mesozoic: 160-125 Ma). Here we report a typhlopoid blind snake from the Late Cretaceous of Brazil, Boipeba tayasuensis gen. et sp. nov, which extends the scolecophidian fossil record into the Mesozoic and reduces the fossil gap predicted by molecular data. The new species is estimated to have been over 1 m long, much larger than typical modern scolecophidians (<30 cm). This finding sheds light on the early evolution of blind snakes, supports the hypothesis of a Gondwanan origin for the Typhlopoidea, and indicates that early scolecophidians had large body size, and only later underwent miniaturization.

8.
Zootaxa ; 4656(3): zootaxa.4656.3.5, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31716812

RESUMO

The crocodylomorph fauna of the Cenozoic of South America is one of the richest and most diverse in the world. The most diverse group within that fauna is Alligatoroidea, with nearly all of its species belonging to the Caimaninae clade. Many of the fossil alligatoroid species from the Cenozoic of South America were proposed based on very incomplete remains, and as a result their validity requires revision. Two such species are Balanerodus logimus Langston, 1965, from the middle Miocene of Colombia and Peru, and Caiman venezuelensis Fortier Rincón, 2012, from the Pliocene-Pleistocene of Venezuela. This study has performed a thorough review of the taxonomic status of these two alligatoroid species, concluding that B. logimus is a nomen dubium and that Ca. venezuelensis is a junior synonym of the extant species Ca. crocodilus. This review offers a significantly more accurate scenario for alligatoroid diversity in the Cenozoic of South America in different epochs such as the Miocene and Pleistocene. Additionally, the record of Ca. crocodilus from the Pleistocene of Venezuela is the first fossil record that can be assigned to this species.


Assuntos
Fósseis , Animais , Colômbia , Peru , Filogenia , América do Sul , Venezuela
10.
PeerJ ; 5: e3056, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28286712

RESUMO

Mourasuchus (Alligatoroidea, Caimaninae) is one of the most peculiar crocodyliforms due to the skull morphology consisting of a long, wide, dorsoventrally flat rostrum with long, slender mandibular rami. Despite these peculiarities, the systematics, phylogeny and feeding habits of this taxon have not been properly studied. In this paper, we describe a new species of the genus, Mourasuchus pattersoni sp. nov., from the late Miocene of the Urumaco Formation of Venezuela. The new species differs from the other Mourasuchus species in having a lateromedially wide, dorsoventrally high jugal bone and a circular incisive foramen, which both represent autapomorphies of the new taxon. Phylogenetically, M. pattersoni sp. nov. is more closely related to M. amazonensis and the specimen UFAC-1424 (formely attributed to M. nativus) than to M. arendsi or M. atopus, whilst Mourasuchus is recovered once more as a monophyletic group. Furthermore, the cladistic analysis performed in this contribution offers a new phylogenetic assessment of Caimaninae, including many taxa described recently for the group. In this study, we also discuss the crocodylian diversity of the Urumaco Formation as well as how paleoenvironment may have contributed toward its evolution. In addition, we provide a discussion of the potential feeding habits of Mourasuchus. In this contribution, Mourasuchus is regarded as a taxon that likely preferred to prey on small animals. The unusual skull morphology of this group may have evolved to cover a large area with the rostrum, allowing for a more efficient prey capture, while the prey may have consisted predominantly of large amounts of small animals.

11.
PLoS One ; 10(9): e0137523, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26355294

RESUMO

The sphenodontian fossil record in South America is well known from Mesozoic and Paleogene deposits of Argentinean Patagonia, mainly represented by opisthodontians, or taxa closely related to the modern Sphenodon. In contrast, the Brazilian fossil record is restricted to the Caturrita Formation, Late Triassic of Rio Grande do Sul, represented by several specimens of Clevosauridae, including Clevosaurus brasiliensis Bonaparte and Sues, 2006. Traditionally, Clevosauridae includes several Late Triassic to Early Jurassic taxa, such as Polysphenodon, Brachyrhinodon, and Clevosaurus, the latter well-represented by several species. The detailed description of the specimen MCN-PV 2852 allowed the first systematic revision of most Clevosaurus species. Within Clevosauridae, Polysphenodon is the most basal taxon, and an IterPCR analysis revealed Brachrhynodon as a possible Clevosaurus; C. petilus, C. wangi, and C. mcgilli as possibly distinct taxonomic entities; and the South African Clevosaurus sp. is not closely related to C. brasiliensis. These data indicate the need of a deep phylogenetic review of Clevosauridae, in order to discover synapomorphic characters among the diversity of these Triassic/Jurassic sphenodontians.


Assuntos
Dinossauros/anatomia & histologia , Animais , Brasil , Geografia , Humanos , Paleontologia , Filogenia , Crânio/anatomia & histologia , Fatores de Tempo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...