Dinoflagellate cysts and acritarchs are excellent proxies for biostratigraphic and paleoceanographic studies in neritic sequences. However, Neogene marine palynological studies in tropical latitudes ...are scarce. Here, we analyzed the marine palynological contents (dinoflagellate cysts, acritarchs, foraminiferal test linings and prasinophytes) of 40 samples from a well drilled in northernmost Colombia, southern Caribbean Sea, spanning the late Chattian–late Burgidalian time interval (~24.1–17.3 Ma). We propose a biostratigraphic scheme that includes an upper Chattian–lower Aquitanian Minisphaeridium latirictum Interval Zone (~23.9–22.0 Ma), an upper Aquitanian Achomosphaera alcicornu Interval Zone (~22.0–20.3 Ma), and a Burdigalian Cribroperidinium tenuitabulatum Interval Zone (~20.3–17.5 Ma). Our results reveal several biostratigraphic events that are heterochronous compared to high latitudes. Furthermore, the conspicuous shift from a peridinioid-dominated to a gonyaulacoid-dominated dinoflagellate cyst assemblage towards the Aquitanian–Burdigalian boundary (~20.7 Ma) indicates a reduction in marine primary productivity. This paleoproductivity decline was probably driven by the initial constriction of the Central American Seaway.
•First detailed early Miocene marine palynological study in the Caribbean Sea.•Biostratigraphic scheme based on dinoflagellate cyst and acritarch events.•Aquitanian peridinioid-dominated assemblages imply nutrient-rich shallow waters.•Burdigalian gonyaulacoid-dominated assemblages imply nutrient-poor shallow waters.•Central American Seaway initial constriction likely drove paleoproductivity shift.
New marine palynomorph taxa recovered from an upper Oligocene–lower Miocene (upper Chattian–upper Burdigalian; ~24–17 Ma) shallow-marine succession drilled in northern Colombia, northwestern South ...America, are herein formally described. These new taxa comprise two peridinioid dinoflagellate cyst species, Cristadinium lucyae sp. nov., and Trinovantedinium uitpensis sp. nov., and the acritarch Quadrina? triangulata sp. nov. During the Aquitanian, C. lucyae sp. nov. occurs consistently, whereas T. uitpensis sp. nov. occurs sporadically. Q.? triangulata sp. nov., a potential key biostratigraphic marker in the tropical Americas, occurs during the middle and upper Burdigalian. Cristadinium lucyae sp. nov. is characterized by having solid, distally tapered to truncated, sutural spinules forming linear low crests. Quadrina? triangulata sp. nov. is characterized by having conical to subconical processes. Trinovantedinium uitpensis sp. nov. is characterized by having verrucate to slightly baculate penitabular processes and denticulate cingulum. In addition, Cristadinium lucyae sp. nov. and Trinovantedinium uitpensis sp. nov. improve our understanding of protoperidiniacean taxonomic diversity.
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•Description of the peridinioid dinocyst Cristadinium lucyae sp. nov.•Description of the acritarch Quadrina? triangulata sp. nov.•Description of the peridinioid dinocyst Trinovantedinium uitpaensis sp. nov.•Quadrina? triangulata sp. nov. is a key biostratigraphic marker for the Burdigalian
The genus Trinovantedinium Reid 1977 comprises eleven NeogeneQuaternary and one Paleogene dinoflagellate cyst taxa that have been successfully used for biostratigraphy. Combining new and published ...records of Trinovantedinium species in the Neogene of the tropical Americas, we report preliminary stratigraphic ranges for T. applanatum (AquitanianRecent), T. ferugnomatum (BurdigalianZanclean), T. glorianum (BurdigalianMessinian), T. papula (AquitanianZanclean), T. uitpensis (AquitanianTortonian), T. variabile (AquitanianRecent) and T.? xylochoporum (AquitanianMessinian) in the region. Although the stratigraphic ranges of T. applanatum, T. variabile and T.? xylochoporum in the tropical Americas seem to be coetaneous with previous records elsewhere, the first appearance datums of T. ferugnomatum, T. glorianum and T. papula seem to be at least ∼2–3 Myr. older in the tropical Americas. In contrast, only the last appearance datum of T. glorianum seems to be ∼4 Myr. younger in the Northern Hemisphere. Our results demonstrate that the Cenozoic marine palynological record of the tropical Americas is therefore key to discriminate dinoflagellate cyst stratigraphic ranges across latitudes.
•Seven out of twelve Trinovantedinium taxa are reported in the tropical Americas.•Five calibrated marine palynological events are used to correlate Neogene rocks.•The stratigraphic record of T. pallidifulvum might be restricted to the Quaternary.•FADs of T. ferugnomatum, T. glorianum and T. papula are ∼2–3 Myr. older.
The Pirabas Formation (Neogene, eastern Brazilian Amazonia) is the only marine Miocene unit in Brazil that crops out on the edge of the equatorial shelf. The formation has a distinctive mixture of ...carbonate and siliciclastic sediments. The paleodiversity of the deposit includes assemblages of foraminifera, ostracods, decapod crustaceans, mollusks, bryozoans, corals, echinoderms, fish, and sirenids. Microfossils are abundant and palynological studies can contribute to accurate paleoenvironmental reconstructions and biostratigraphic descriptions of the Pirabas formation. Here, we present 17 samples from eight outcrops and one quarry belonging to the Pirabas Formation with a goal to understand their depositional environments and relative ages. We recorded 9 species of dinoflagellate cysts, 7 spore species morphotypes, 59 pollen species morphotypes, 17 species of diatoms, and one species of silicoflagellate. We clustered the samples into two depositional groups, with one group formed by the Capanema quarry, Ponta do Castelo and Fazenda outcrops, deposited in a mesotrophic, shallow, marine environment, with a late early-Miocene age. The second one, formed by Atalaia, Aricuru, Maçarico, and Baunilha Grande outcrops, was deposited in a mesotrophic coastal environment with nearby mangroves; these samples may date to the late middle to late Miocene.
•Pirabas Formation has an age of late early to late Miocene.•Coastal and shallow marine environments prevailed for Pirabas Formation.•Pirabas Formation shows the change in deposition of the Brazilian equatorial margin.
La enseñanza asistida por pares es una metodología educativa donde interactúan grupos de estudiantes. Una parte toma el rol de educador, y la otra toma el rol de alumno. Esto trae varios beneficios a ...ambas partes. Se presenta el caso de un programa donde se utiliza esta metodología, en el cual estudiantes de una facultad de Medicina en Lima, Perú toman el rol de tutores de estudiantes de años menores de la misma facultad. Se describen también sus actividades y los recursos académicos utilizados.
Peer teaching is an educational methodology in which groups of students interact among each other. One group takes on the role of the educator and the other one takes on the role of the student, which benefits both of them. We report here the case of a program where this methodology was used by students in a medical school in Lima, Peru, who were tutors of junior students from the same faculty. The activities and resources used in this methodology are also described.
Echitriporites trianguliformis and E. suescae comb. nov. are two species of proteaceous-like triaperturate pollen that have been widely reported in several sedimentary sequences from northern South ...America, especially in Colombia and Venezuela. Despite their biostratigraphic significance and because of their morphological similarity, distinction between the two species has been difficult, leading to a biased understanding of their chronostratigraphic ranges. In this study, we compare 75 pollen grains spanning the Maastrichtian-Danian time interval through traditional and geometric morphometrics, and a newly proposed Procrustes-based method (index of pollen curvature). Traditional assessments show subtle variation between specimens; however, geometric morphometrics and the curvature index allow quantifying morphological differences in the degree of concavity-convexity through time. Therefore, geometric morphometrics and curvature index results enable us to constrain the stratigraphic ranges of both taxa. We suggest a coetaneous range for E. trianguliformis and E. suescae comb. nov. during the Late Cretaceous, but the presence of only E. trianguliformis after the Cretaceous-Paleogene boundary event. In addition, we propose a threshold value of 1.5 µm for the curvature index as a tool for distinguishing between these two taxa. We conclude that the combination of geometric morphometrics and the curvature index provides a powerful tool to distinguish between morphological closely-related pollen taxa that are difficult to distinguish through both light microscope visual comparisons and statistical analysis of morphometric measurements.
RESUMENEl objetivo del presente artículo radica en analizar la eficacia de las medidas de protección para niños, niñas y adolescentes y la protección integral como mecanismo de prevención de la ...vulneración de los derechos establecidos en la Constitución. En consecuencia, La metodología utilizada respondió al análisis bibliográfico documental y dicha información fue sistematizada mediante un análisis cualitativo de carácter deductivo. Como resultado de la investigación se establece la necesidad de crear una política pública integral que dé seguimiento a la ejecución y cumplimiento de las resoluciones dictadas por los operadores de justicia en cuanto a medidas de protección se refiere, cumpliendo con los parámetros necesarios de aprobación del borrador de política pública por autoridad competente, conformación de un equipo interdisciplinario y elaboración de un plan estratégico para la producción del documento, junto con el análisis y socialización ante la ciudadanía de la problemática a tratar.
El arte artesanal es una actividad subjetiva para el espectador, ya que su percepción puede variar según las circunstancias y el contexto que lo rodea. Incluso la valoración económica de este tipo de ...obras es subjetiva, lo que puede resultar en una remuneración insuficiente o, por el contrario, en una cotización elevada en el mercado. Por eso, este trabajo se centró en determinar cómo las redes sociales pueden influir en el valor de los productos artesanales. Para ello, se empleó una metodología cualitativa, de naturaleza exploratoria y descriptiva, respaldada por una revisión bibliográfica exhaustiva que abarcó trabajos recientes indexados en bases de datos como JCR, Scopus y Latindex. La metodología utilizada se sustentó en la teoría fundamentada y en los principios del interaccionismo simbólico de Mead. El área de estudio se limitó al ámbito de la joyería artesanal, dado que en este sector se sigue trabajando de manera artesanal, incluso cuando incorpora diversas tecnologías para mejorar su producción. Para recabar la información, se llevaron a cabo entrevistas con propietarios de negocios en la ciudad de México, y cada caso fue analizado en relación con su presencia y estrategia en el entorno digital. Los resultados obtenidos permiten comparar la situación de estas empresas durante y después de la pandemia del SARS-CoV-2 con el fin de comprender las mejoras y los resultados derivados de su participación en las redes sociales y evaluar la valoración estimada de sus productos.
Understanding the origin of the diversity in Central American forests requires the integration of both extant and fossil taxa. Here, we provide a description of Humiriaceae fossils from two new ...sedimentary sequences in the Azuero Peninsula, Panamá. Fossils were recovered from Oligocene (one locality) and Early Miocene (two localities) marginal marine deposits. We describe new specimens and augment the generic description ofLacunofructus cuatrecasanaHerrera, ManchesteretJaramillo, and present a new record ofSacoglottissp. Our results expand the temporal and geographical distribution of both taxa and show that Humiriaceae was an important constituent of early Central American forests, and that this family was dispersed in between Central and South America before the final closure of the Central American Seaway. Further studies are necessary to establish whether the origin of this family was in Central or South America.
Para entender el origen de la diversidad de los bosques de América Central, se necesita integrar estudios de plantas actuales y fósiles. En este trabajo, describimos fósiles de Humiriaceae, excavados de dos nuevas secuencias sedimentarias en la Península de Azuero, Panamá. Los fósiles fueron encontrados en depósitos marinos-marginales del Oligoceno (una localidad) y del Mioceno temprano (dos localidades). Describimos nuevos especímenes y aumentamos la descripción morfológica de Lacunofructus cuatrecasana Herrera, ManchesteretJaramillo para las localidades del Oligoceno y Mioceno temprano y presentamos un nuevo registro de Sacoglottis sp., para el Mioceno temprano. Estos nuevos registros expanden los rangos de distribución geográfica y temporal para ambos taxones, y además demuestran que la familia Humiriaceae fue un importante constituyente de los primeros bosques en América Central. La evidencia presentada también sugiere que hubo dispersiones de especies de Humiriaceae entre Centro y Sur América mucho antes del cierre del Istmo de Panamá. Se necesitan más estudios para establecer con claridad si el origen de Humiriaceae se dio en América Central o Sur América.
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