Ameghiniana最新文献

{"title":"These are Fossils Too: A Look at the Study of Ancient Biomolecules.","authors":"D. Pérez","doi":"10.5710/1851-8044-60.3.277","DOIUrl":"https://doi.org/10.5710/1851-8044-60.3.277","url":null,"abstract":"","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45469967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Systematic Revision of Interatherium and Icochilus (Interatheriidae, Notoungulata) from the Santa Cruz Formation (Early To Middle Miocene), Santa Cruz Province, Argentina","authors":"Mercedes Fernández, J. Fernicola, E. Cerdeño","doi":"10.5710/AMGH.12.01.2023.3541","DOIUrl":"https://doi.org/10.5710/AMGH.12.01.2023.3541","url":null,"abstract":"Abstract. Interatheriidae (late Paleocene–Late Miocene) is one of the most morphologically derived families within Order Notoungulata and the most taxonomic diverse and abundant clade of extinct South American Native Ungulates. Most of the interatheriids described during late 19th century were erected from specimens collected from the prolific Santa Cruz Formation (Santacrucian SALMA; Burdigalian–early Langhian), Santa Cruz Province (Argentina). Interatherium, the type genus of the family, and Icochilus, a closely related genus, were last revised more than a century ago, and most species were considered Typotheria incertae sedis. This contribution provides the taxonomic revision of these genera, made within the framework of an exhaustive unpublished systematic revision of Interatheriinae. We propose several synonyms, including the synonymy between both genera. We conclude that Interatherium is comprised of I. rodens and I. extensus, and consider Interatherium supernum as nomen nudum according to its first description in 1887, and Interatherium brevifrons and Icochilus curtus as species inquirenda. This taxonomic scheme is supported by a phylogenetic analysis, in which Interatherium is recovered as a monophyletic genus and as the sister taxon of the clade Neoicochilus plus Cochilius. In a biostratigraphic context, it is not possible to subdivide the Santa Cruz Formation based on the presence/absence of any species of Interatherium, due to their wide geographic and temporal distribution. Finally, the localities from the Atlantic coast (east) and Río Santa Cruz (central) are similar in their content concerning Interatherium, but both differ from that of the western area, which lacks any evidence of this genus. Resumen. Los Interatheriidae (Paleoceno tardío–Mioceno Tardío) constituyen una de las familias más derivadas dentro del Orden Notoungulata, el clado más diverso y abundante de ungulados nativos sudamericanos. La mayoría de los interatéridos descritos durante fines del siglo XIX fueron fundados a partir de especímenes recolectados en la Formación Santa Cruz (Edad Mamífero Santacrucense; Burdigaliano–Langhiano temprano), Santa Cruz (Argentina). Interatherium, el género tipo de la familia, e Icochilus, un género muy afín a éste, fueron revisados por última vez hace más de un siglo y la gran mayoría de las especies fueron consideradas Typotheria incertae sedis. Esta contribución proporciona la revisión taxonómica de estos géneros, realizada en el marco de una exhaustiva revisión sistemática inédita de los Interatheriinae. Proponemos múltiples sinonimias, incluyendo la sinonimia entre ambos géneros, concluimos que Interatherium está constituido por I. rodens e I. extensus, y consideramos a Interatherium supernum como nomen nudum de acuerdo con su primera descripción en 1887 e Interatherium brevifrons e Icochilus curtus como species inquirenda. Este esquema taxonómico está soportado por un análisis filogenético, en el cual Interatherium se recupera ","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43887697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New Miocene–Pliocene Specimens of Toxodontidae (Notoungulata) from the Huayquerías of Mendoza, West-Central Argentina","authors":"E. Cerdeño, G. I. Schmidt, Cristo O. Romano, Analía M. Forasiepi","doi":"10.5710/AMGH.19.03.2023.3547","DOIUrl":"https://doi.org/10.5710/AMGH.19.03.2023.3547","url":null,"abstract":"Abstract. We describe three new Toxodontidae (Notoungulata) remains from Mendoza Province, west-central Argentina. One is a new mandible (IANIGLA-PV 993) collected at Huayquerías del Este, from the Huayquerías Formation (Late Miocene–earliest Pliocene). This finding adds to two other unpublished specimens from the area stored in old collections. MCNAM-PV 113 is a skull fragment from Huayquerías de San Carlos, lacking exact origin data, and MACN PV 14854 corresponds to associated upper and lower teeth from the so-called Bajada Grande locality, in Huayquerías del Este, from levels now assigned to the Bajada Grande Formation (Late Pliocene–Pleistocene). IANIGLA-PV 993 and MCNAM-PV 113 belong to Xotodon major. This species was described in 1914 based on cranial remains likely from levels now assigned to the Tunuyán Formation. Slight differences between IANIGLA-PV 993 and the holotype of X. major are attributable to intraspecific variation and their ontogenetic stage: smoother anteroventral mandibular angle; ascending ramus with blunt crest between the fossae for the zygomaticomandibularis and masseteric muscles; and tooth features (e.g., p4 with deeper grooves and slightly shorter teeth) that relate to a lesser wear degree. MCNAM-PV 113 shows nasals and upper teeth comparable with the holotype, although teeth are slightly less compressed. The temporal gap between levels yielding the holotype and IANIGLA-PV 993 is not reflected by our taxonomical interpretation. Finally, the specimen MACN PV 14854 is identified as Toxodon chapalmalensis, based upon its similarities with specimens from the Chapadmalal area, Buenos Aires Province, showing a correspondence with the Chapadmalalan Stage/Age of the Pampean Region. Resumen. Se describen tres restos de Toxodontidae (Notoungulata) de Mendoza, centro-oeste de Argentina. La mandíbula IANIGLA-PV 993 procede de la Formación Huayquerías (Mioceno Tardío-Plioceno más temprano) en las Huayquerías del Este. Éste se suma a dos especímenes inéditos del área pertenecientes a colecciones antiguas. MCNAM-PV 113 es un fragmento craneal de las Huayquerías de San Carlos, sin datos precisos de procedencia, y MACN PV 14854 incluye dentición superior e inferior asociada, colectada en la localidad Bajada Grande, Huayquerías del Este, en niveles asignados a la Formación Bajada Grande (Plioceno Tardío–Pleistoceno). IANIGLA-PV 993 y MCNAM-PV 113 pertenecen a Xotodon major. Esta especie se describió en 1914 a partir de restos craneales probablemente de niveles hoy asignados a la Formación Tunuyán. Las pequeñas diferencias entre IANIGLA-PV 993 y el holotipo de X. major son atribuibles a variación intraespecífica y los respectivos estados ontogenéticos: ángulo anteroventral mandibular más suave; rama ascendente con cresta roma entre las fosas para los músculos cigomático-mandibular y masetero; y rasgos dentarios (e.g., surcos más profundos en p4, dientes ligeramente más cortos) relacionados con el menor grado de desgaste. MCNAM-PV 113 m","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46192428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First Discinid Brachiopods (Brachiopoda: Lingulida) from the Cenozoic of Patagonia (Gaiman Formation, Lower Miocene, Argentina)","authors":"D. Pérez, Nicolás D. Farroni, Aylén Allende Mosquera, J. Cuitiño","doi":"10.5710/AMGH.23.01.2023.3544","DOIUrl":"https://doi.org/10.5710/AMGH.23.01.2023.3544","url":null,"abstract":"Abstract. Discinids are a group of inarticulate brachiopods with organophosphatic shells and a very poor fossil record. We report for the first time the presence of this family in the Cenozoic of Patagonia, represented by two new species: Discinisca porvenir sp. nov. and Discinisca messii sp. nov., both found in marine deposits of the Gaiman Formation (Lower Miocene) in Chubut province, Argentina. Specimens come from four localities: Bryn Gwyn, Cañadón del Puma, Isla Escondida, and Punta Loma. The first species, D. porvenir sp. nov., presents a shell with subcircular to subtrapezoidal outline in dorsal view and maximum width located slightly anterior, apex near to the last quarter of the total valve length, and external sculpture formed by narrow concentric bands with irregular edges. In contrast, the second species, D. messii sp. nov., shows a valve with subcircular to circular outline in dorsal view with apex placed near to posterior margin, and external sculpture formed by concentric bands with a rounded triangular profile in transverse section. The new species seem to be related to the living D. lamellosa and D. laevis, respectively, both with a western South American distribution. The Gaiman Formation includes phosphatic nodules and abundant cases of well-preserved phosphatic vertebrate remains. Due to this, and the biostratinomic conditions deduced for vertebrates, the preservation of the brachiopods could be favoured. Resumen. Los discinidos son un grupo de braquiópodos inarticulados con valvas organofosfáticas y un registro fósil muy pobre. En este trabajo reportamos por primera vez la presencia de esta familia en el Cenozoico de Patagonia, representada por dos especies nuevas: Discinisca porvenir sp. nov. y Discinisca messii sp. nov., ambas encontradas en depósitos marinos de la Formación Gaiman (Mioceno Inferior) en la provincia del Chubut, Argentina. Los especímenes provienen de cuatro localidades: Bryn Gwyn, Cañadón del Puma, Isla Escondida y Punta Loma. La primera especie, D. porvenir sp. nov., presenta una valva con contorno subcircular a subtrapezoidal en vista dorsal, con el ancho máximo situado levemente anterior, y el ápice cerca del último cuarto del largo total, y ornamentación externa dada por bandas concéntricas angostas con bordes irregulares. Por otro lado, la segunda especie, D. messii sp. nov., muestra una valva con contorno subcircular a circular en vista dorsal con el ápice cerca del margen posterior, y ornamentación externa dada por bandas concéntricas con perfil triangular redondeado en sección transversal. Las nuevas especies parecieran estar relacionadas con los taxones vivientes D. lamellosa y D. laevis, respectivamente, ambos con distribución en el oeste de América del Sur. La Formación Gaiman incluye nódulos fosfáticos y casos abundantes de restos de vertebrados fosfáticos muy bien preservados. Debido a ello, y a las condiciones bioestratinómicas deducidas a partir de los vertebrados, la preservación de los braq","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41785062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New Species of the Genus Arbacia (Echinoidea, Arbaciidae) from the Neogene of Chile","authors":"Erwan Courville, M. Gonzalez, F. Mourgues, E. Poulin, T. Saucède","doi":"10.5710/AMGH.01.03.2023.3536","DOIUrl":"https://doi.org/10.5710/AMGH.01.03.2023.3536","url":null,"abstract":"Abstract. Recent fieldwork on Neogene deposits of northern Chile led to the discovery of new material, including three new species of the echinoid genus Arbacia: Arbacia quyllur sp. nov. from the Miocene, Arbacia terraeignotae sp. nov., and Arbacia larraini sp. nov. from the Pliocene. In the Pleistocene, the new material includes the first fossil occurrence of the extant species Arbacia spatuligera and new specimens of the extant species Tetrapygyus niger. The specimens and new species described here reveal the significant past diversity of the genus Arbacia and increase our knowledge of the overall diversity of the genus in South America, showing an older origin (upper Miocene) and higher species richness of the genus Arbacia along the Chilean coasts than previously thought. Resumen. Recientes trabajos de campo en el Neógeno del norte de Chile han permitido descubrir nuevos materiales, entre ellos tres nuevas especies del género de equinoideo Arbacia: Arbacia quyllur sp. nov. (Mioceno), Arbacia terraeignotae sp. nov. y Arbacia larraini sp. nov. (Plioceno), pero también la primera aparición de Arbacia spatuligera y nuevo material de Tetrapygyus niger (Pleistoceno). Los especímenes y las nuevas especies aquí descritas revelan la diversidad pasada del género Arbacia. Estos descubrimientos muestran la existencia de una mayor riqueza de Arbacia a lo largo de las costas chilenas y un origen más antiguo del género en la costa del Pacífico Sureste (Mioceno superior).","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42442795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gondwanan Perspectives: Triassic Ecosystems. Paleobiological Aspects and the Context of Recovery from the Great Extinction","authors":"A. Arcucci, A. Mancuso","doi":"10.5710/AMGH.27.03.2023.3554","DOIUrl":"https://doi.org/10.5710/AMGH.27.03.2023.3554","url":null,"abstract":"<jats:p>n/a</jats:p>","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48162672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Reassessment of the Mandibular Anatomy of Dinodontosaurus brevirostris (Synapsida, Dicynodontia) from the Ladinian–Early Carnian Chañares Formation (Northwestern Argentina), and Its Taxonomic and Phylogenetic Significance","authors":"J. Escobar, A. Martinelli, M. Ezcurra, L. Fiorelli, M. Baczko, F. Novas, J. Desojo","doi":"10.5710/AMGH.24.10.2022.3532","DOIUrl":"https://doi.org/10.5710/AMGH.24.10.2022.3532","url":null,"abstract":"Abstract. Two lineages of Kannemeyeriiformes (Synapsida, Dicynodontia) are currently known in the Ladinian–Carnian Chañares Formation (Ischigualasto-Villa Unión Basin, Argentina): stahleckeriine stahleckeriids, based upon postcrania, and a single non-stahleckeriine species, Dinodontosaurus brevirostris, known mostly by cranial material. Available data on the mandible of Dinodontosaurus brevirostris is mainly based on specimen PULR-V 03, holotype of D. “platygnathus”. Here we present a comprehensive and comparative osteological study of the lower jaw of D. brevirostris, based on PULR-V 03 and the new specimens CRILAR-Pv 94 and PULR-V 144, and revise its phylogenetic relationships with the inclusion of the mandibular data. Our results resemble previous analyses, with a monophyletic Dinodontosaurus as the sister group of the Angonisaurus + Stahleckeriidae clade. Dinodontosaurus brevirostris is reinterpreted has having an angular contribution to the mandibular symphysis, rounded and hypertrophied reflected lamina of the angular, wide angular gap, and well-developed and anteriorly curving retroarticular process. Previous hypotheses of stahleckeriine affinities are rejected based on the markedly convex symphysial chin, wide angular gap, median symphysial ridge, and moderately sloping articular surface, but the shape and size of the reflected lamina is consistent with the position of Dinodontosaurus as a close relative of Stahleckeriidae. Traits potentially relevant for the distinction from D. tener and other kannemeyeriiforms (tall medial ridge on the dentary table, anterolateral trough in the angular, angular contribution to symphysis, extreme narrowness of the symphysial ridge, wide and deep median dentary groove) need further research in other dicynodont groups in order to robustly interpret their evolutionary history. Resumen. Actualmente se reconocen dos linajes de Kannemeyeriiformes (Synapsida, Dicynodontia) en la Formación Chañares del Ladiniano–Carniano (Cuenca de Ischigualasto-Villa Unión, Argentina): stahleckériidos stahleckeriinos, basados en postcráneos, y una sola especie de no-stahleckeriinos, Dinodontosaurus brevirostris, conocida principalmente por material craneano. Los datos disponibles sobre la mandíbula de Dinodontosaurus brevirostris se basan principalmente en el espécimen PULR-V 03, holotipo de D. “platygnathus”. Aquí presentamos un estudio osteológico completo y comparativo de la mandíbula de D. brevirostris, basado en PULR-V 03 y los nuevos especímenes CRILAR-Pv 94 y PULR-V 144, y revisamos sus relaciones filogenéticas con la inclusión de los datos mandibulares. Nuestros resultados son similares a análisis previos, con un Dinodontosaurus monofilético como grupo hermano del clado Angonisaurus + Stahleckeriidae. Dinodontosaurus brevirostris es reinterpretado con una contribución del angular a la sínfisis mandibular, lámina replegada del angular redondeada e hipertrofiada, gap angular amplio, y proceso retroarticular bien desarroll","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45856528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evidences of Teratology and Mutagenensis in Palynological Assemblages from the Middle Triassic Puesto Viejo Group, San Rafael Depocenter, Argentina. Implications of Volcanism and Regional Environmental Stress","authors":"A. Zavattieri, P. R. Gutiérrez","doi":"10.5710/AMGH.24.01.2023.3533","DOIUrl":"https://doi.org/10.5710/AMGH.24.01.2023.3533","url":null,"abstract":"Abstract. Evidence of teratogenesis and mutagenesis documented in the palynological assemblages of the Middle Triassic Quebrada de los Fósiles Formation, San Rafael Depocenter (Mendoza, Argentina) provide an independent testimony of deteriorating atmospheric conditions at the time of sedimentation of the lower unit of the Puesto Viejo Group. Considerable explosive acid volcanism occurred during the deposition of the continental alluvial-fluvial systems of this unit, and its consequent effects on climate created stressful and adverse conditions that influenced the paleoenvironments and vegetation. To assess the degree of teratology, we characterize malformation categories for each lineage of plants represented in the dispersed palynomorphs (spores, saccate pollen, and algae) recorded in the Quebrada de los Fósiles microflora. Additionally, typical fused spores are associated with malformed tetrads, triads, and dyads which reflect reactions of the autochthonous plants (sphenophytes, ferns, bryophytes, and lycophytes) to adverse environmental conditions. Unusual morphologies are also evident in some aquatic zygospores of green algae that colonized the freshwater bodies within fluvial systems of the middle and upper sections of this unit. The palynological preparations also contain dispersed leaf cuticle fragments showing xeromorphic features that reveal mutagenetic responses of plants to paleoenvironmental stresses. The co-occurrence of morphological aberrancies observed in different lineages of palynomorphs is consistent with previous interpretations that the terrestrial and aquatic vegetation of the Quebrada de los Fósiles Formation grew in disturbed floodplain environments affected by intermittent volcanic episodes under temperate to warm seasonal arid to semiarid climatic conditions. In this contribution, we document the first clear diversity of teratological traits independently developed across different lineages of plants and possibly algae synchronously coinciding with intense explosive volcanism within the same region in the Middle Triassic. Resumen. Evidencias de teratogénesis y mutagénesis documentadas en las asociaciones palinológicas de la Formación Quebrada de los Fósiles, Triásico Medio, Depocentro de San Rafael (Mendoza, Argentina) proveen un testimonio independiente del deterioro de las condiciones atmosféricas durante la sedimentación de la unidad inferior del Grupo Puesto Viejo. Un considerable vulcanismo ácido explosivo ocurrió durante la depositación de los sistemas aluviales-fluviales continentales de esta unidad y sus consecuentes efectos sobre el clima crearon condiciones estresantes y adversas que influyeron en los paleoambientes y en la vegetación. Para evaluar el grado de teratología identificamos categorías de malformaciones para cada linaje de planta representada en los palinomorfos dispersos (esporas, polen sacado y algas) registrados en las microfloras de la Quebrada de los Fósiles. Además, las esporas fusionadas norma","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41623534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Macro- And Micromorphology of Scales from an Endemic South American Actinopterygian Family (Pseudobeaconiidae, Triassic, Cuyana Basin)","authors":"P. Giordano, C. Benavente, Sofía A. Suárez Davi","doi":"10.5710/AMGH.03.02.2023.3540","DOIUrl":"https://doi.org/10.5710/AMGH.03.02.2023.3540","url":null,"abstract":"Abstract. Pseudobeaconiidae is a South American endemic actinopterygian family recorded in the Middle–Late Triassic Cuyana and Ischigualasto-Villa Unión rift basins. This family has been studied for more than seven decades by several authors. In spite of that, the morphological information about their scales is not complete, especially the one related to micromorphology, which has remained unknown until now. The main goal of this contribution is to provide new macro- and micromorphological information of scales from new material of Pseudobeaconiidae, including a brief revision of the scales of the family based on our own observations from material collections. The new studied specimens were recovered from the center lake facies of the Santa Clara Abajo Formation with detailed stratigraphic control. The macromorphology of isolated scales confirms a peg-and-socket articulation in this newly studied material. New features described also include the squamation general pattern, including the scales of the lateral line, the ventral margin, that is characterized by round or angular scales, and the presence of ganoine ornamentations covering preanal and postanal scutes. Regarding micromorphology, paleohistology shows lepidosteoid-type ganoid scales and; also, possible transitional ganoid scales between lepidosteoid and palaeoniscoid-type. Detailed morphological studies on Triassic fish faunas are necessary to obtain clearer patterns that contribute to the understanding of the evolution of Actinopterygii from Gondwana. Resumen. Pseudobeaconiidae es una familia de Actinopterygii endémica de América del Sur registrada en el Triásico Medio–Tardío de las cuencas de rift Cuyana y de Ischigualasto-Villa Unión. Esta familia ha sido estudiada durante más de siete décadas por varios autores. A pesar de eso, la información morfológica sobre sus escamas es incompleta, especialmente aquella relacionada con la micromorfología de escamas, que ha permanecido desconocida hasta el momento. El objetivo principal de esta contribución es proporcionar nueva información macro y micromorfológica de las escamas de Pseudobeaconiidae, a partir de material nuevo, incluyendo una breve revisión de las escamas de la familia basada en observaciones propias de material de colecciones. Los nuevos especímenes estudiados fueron recuperados de facies de centro lago de la Formación Santa Clara Abajo bajo control estratigráfico detallado. La macromorfología de las escamas aisladas confirman una articulación de tipo “peg-and-socket” en el nuevo material estudiado. Los nuevos rasgos descriptos incluyen también el patrón general de escamación incluyendo las escamas de la línea lateral, el margen ventral, que se caracteriza por presentar escamas redondeadas o angulosas, y la presencia de escudos preanales y postanales con ornamentaciones de ganoína. En cuanto a la micromorfología, la paleohistología muestra escamas ganoides de tipo lepidosteoide y, posiblemente también escamas ganoides de transic","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49303406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Late Triassic Calcareous Nannofossils from Arroyo Malo Formation, Neuquén Basin, Argentina. Implications for Their Early Evolution and Dispersal","authors":"J. P. P. Panera, G.N. Angelozzi, A. Riccardi, S. Damborenea, M. Manceñido","doi":"10.5710/AMGH.13.10.2022.3526","DOIUrl":"https://doi.org/10.5710/AMGH.13.10.2022.3526","url":null,"abstract":"Abstract. The Arroyo Malo Formation represents the first marine ingression during the Late Triassic in the Neuquén Basin, west-central Argentina. The presence of calcareous nannofossils in this unit provides an independent age constraint of a late Norian to Rhaetian age for its lower and middle parts, in agreement with known fossil invertebrates. Furthermore, this represents one of the only three records of this group known so far outside the Tethyan Realm. The presence of monospecific assemblages of Prinsiosphaera triassica in the late Norian and assemblages characterized by P. triassica and Eoconusphaera zlambachensis in the Rhaetian, together with a review of other known records worldwide, allows the formal proposal of a global biozonation for the Late Triassic. Prinsiosphaera triassica Biozone, from middle Norian to late Norian, and Crucirhabdus primulus Biozone, spanning the Rhaetian (comprising two sub-biozones in the Tethys), are defined. Based on the new record from the Upper Triassic of the Neuquén Basin, we interpret that calcareous nannofossils originated during the middle Norian in the Western Tethys, and we suggest that they then rapidly dispersed to the Southeastern Tethys and from there to the Eastern Pacific across Panthalassa by southern mid-latitude easterly oceanic currents. Resumen. La Formación Arroyo Malo representa la primera ingresión marina durante el Triásico Tardío en la Cuenca Neuquina, centro-oeste de Argentina. La presencia de nanofósiles calcáreos en esta unidad permite la datación independiente de una edad Noriano tardío a Rhaetiano en su parte inferior y media, que se halla de acuerdo con la edad propuesta a partir de los invertebrados fósiles conocidos. Este es además uno de los tres únicos registros de este grupo detectados fuera del Reino del Tethys. La presencia de ensambles monoespecíficos de Prinsiosphaera triassica en el Noriano tardío y ensambles caracterizados por P. triassica y Eoconusphaera zlambachensis en el Rhaetiano, junto con una revisión de los otros registros conocidos a nivel mundial, permite proponer formalmente una biozonación global para el Triásico Tardío. Se definen la Biozona de Prinsiosphaera triassica, con un rango Noriano medio a Noriano tardío, y la Biozona de Crucirhabdus primulus, que abarca el Rhaetiano y que comprende dos sub-biozonas que aplican en la región del Tethys. Sobre la base del novedoso registro de nanofósiles calcáreos en el Triásico Superior de la Cuenca Neuquina, se reafirma la idea que los nanofósiles calcáreos se originaron en el Noriano medio en el Tethys occidental y se propone que se dispersaron rápidamente hacia el Tethys sudoriental y, desde allí, al Pacífico oriental a través de Panthalassa por corrientes oceánicas de latitudes medias australes con sentido oesteeste","PeriodicalId":50819,"journal":{"name":"Ameghiniana","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43687868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}