http://rid.unrn.edu.ar:8080/handle/20.500.12049/205 Sun, 19 Apr 2026 18:41:19 GMT 2026-04-19T18:41:19Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/12927 Título: Diversidad de peces holósteos en niveles de la Formación Cerro Lisandro (Cenomaniano -Turoniano, Cretácico Superior) aflorantes en la localidad de Cerro Bayo Mesa, Provincia de Neuquén. Autor(es): Guzmán, Federico Agustín Abstract: Holostean are a group of actinopterygian fishes, whose fossil record extends from the Late Permian/Early Triassic up to the present. The classification and phylogenetic relationships of this group are still under debate, but it is composed of the divisions Ginglymodi, Halecomorphi and the Order Dapediiformes. The clade Holostei presents an interesting evolutionary history during the Mesozoic, with eight species currently recorded. In Argentina, this group of fishes is recorded in various sedimentary basins mainly in the Jurassic - Cretaceous, with a scarce fossil record that consists mainly of scales, vertebrae and teeth. The goal of this Final Degree Work is to describe and analyze isolated remains of holostean fishes from the Cerro Bayo Mesa locality (Cerro Lisandro Fm., middle-upper Turonian) in the province of Neuquén, Argentina. These remains consist of cranial fragments, vertebral centra, and scales, most of which are unpublished and preliminarily assigned to the family Lepisosteidae. The cranial fragments and vertebral centra were described anatomically and compared through the bibliography, whereas the scales were described morphologically and thin sections were made to study their microstructure. Thus, a premaxilla is assigned to the Amiidae family, a dentary fragment, a possible dentary fragment and a cranial bone, tentatively assigned as cf. Amiidae. Therefore, the vertebral centra were assigned to the Vidalamiinae subfamily. Finally, the assignment to Lepisosteidae of the scales and a vertebral centra is confirmed. At the same time, the possible systematic affinities of these materials are discussed, the diversity present from the associated materials, and the possible occurrence of the genus Melvius, based on a vertebral centra and the implications of the presence of this genus. Finally, the importance of the records studied here is highlighted, which represent new occurrences, expanding the knowledge of this group of fishes in Argentina. Thu, 08 May 2025 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/12927 2025-05-08T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/12666 Título: Estudio morfo-anatómico de frutos de palmeras de la formación Chichinales (mioceno inferior) procedentes de paso córdoba, Provincia de Río Negro, Argentina. Autor(es): Muci Ruiz, Ana Luciana Abstract: The Area Natural Protegida Paso Córdoba (ANPPC) in the Río Negro province (Argentina) has Lower Miocene outcrops that belong to the Chichinales Formation. The fossil record of this unit is restricted to its lower section and includes a diverse fauna. Regarding the fossil flora, only permineralized woods assigned to Nothofagoxylon menendezii Ragonese and other plant remains still not studied have been recorded. Based on the review of materials from collections and new samplings from fieldwork, abundant fruits, and stems of palm trees (Arecaceae) have been identified. The fruits (drupes) are preserved in large concentrations in sandstone banks with a cross-shaped structure. They consist of pyrenes preserved as permineralizations and molds which constitute the subject of study of the present work. All the specimens studied were included in the fossil genus Palmocarpon Lesq. The morphological and anatomical characteristics of the fossil fruits were compared with those of several groups of fossil and extant palms, allowing their assignment to the subtribe Attaleinae (Cocoseae, Arecoideae) with a high degree of confidence. These fruits constitute the first fossil record of Attaleinae for southern South America, being one of the most reliable fossil records of this subtribe for the continent. Anatomically preserved palm stipes and other coniferous logs have been found associated with the fruits. The abundance and wide spatial distribution of the palm record in the lower section of Chichinales Formation suggests that during the Lower Miocene a plant community developed in the area in which palms constituted one of the dominant elements of the tree stratum and most likely as open communities. Tue, 18 Feb 2025 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/12666 2025-02-18T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/12471 Título: Mutaciones feministas en torno al concepto de ciudadanía. Primera aproximación Autor(es): Piccone, María Verónica Sun, 01 Jan 2023 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/12471 2023-01-01T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/12200 Título: Caracterización histológica y osteológica de la neumaticidad en la región caudal del titanosaurio Rocasaurus muniozi (Sauropoda: Titanosauria). Autor(es): Fernández, Matías Ezequiel Abstract: Saltasaurini is a derived clade of titanosaurian sauropods whose members are characterized by their small size, dermal ossicles, and a high development of postcranial pneumaticity. Such pneumaticity is generally recognized by osteological correlates, although recently it has been proposed that it can be identified at the histological level through the presence of pneumosteal tissue (or pneumosteon). In addition, postcranial pneumaticity can be measured at the morphological level through the calculation of the aerial space proportion (ASP), which indirectly infers the space of the osseous element occupied with air. The following bachelor’s degree final project focuses on the osteological and histological correlates of caudal vertebrae assigned to Rocasaurus muniozi, a saltasaurine from the Late Cretaceous of the Allen Formation, from the locality of Salitral Moreno, of the Rio Negro Province in the Argentinian Patagonia. The objectives of the work proposed here are to identify pneumosteal tissue within internal or external cavities, in order to increase its register; to analyze differences regarding its development among the internal structure types (i.e. camellate tissue and camerae); and to compare the ASP value between transversal and longitudinal sections, to evaluate if a preference for the type of orientation in the section exists. In order to achieve these objectives, histological sections were made and observed afterwards with a petrographic microscope. Additionally, tomographic sections were obtained and digitally processed using the software Adobe Photoshop, and the ASP calculation was developed by the software ImageJ. As a result of the histological analysis, for the first time in the caudal series of a titanosaurian sauropod a potential register of pneumosteon was recognized, located in endosteal trabecular bone associated to camellate tissue. Regarding the ASP analysis, the values vary between 0.64-0.68 for the MPCA-Pv-SM 47 element; between 0.51-0.56 in the MPCA-Pv-SM 46/9; and between 0.48-0.5 for the MPCA-Pv-SM 605 vertebrae. The ASP value difference between transversal and longitudinal sections is 0.02-0.04. In conclusion, it was also found that there is no preferred section orientation for developing the ASP analysis. Mon, 04 Nov 2024 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/12200 2024-11-04T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/11683 Título: Estudio de huellas de afinidad mamaliana de la Formación Yacoraite, Valle del Tronco, provincia de Salta, y sus implicancias paleobiológicas Autor(es): Migliaro Petroni, Franco Abstract: In this Final Degree Project, small footprints collected from rocks of the Yacoraite Formation (Maastrichtian-Danian), from Quebrada Sunchales Sur, south of the Valle del Tonco, in the Salta Province, Argentina, were analyzed. The geological formation is characterized by an abundant and diverse fossil record, both corporeal and ichnological, in addition to levels with microbialites, stromatolites, and evidence of sedimentary structures induced by microbial activity (ESIAM, the acronym in Spanish). The paleoenvironmental context is a carbonate basin, with shallow waters of epicontinental platforms, with the presence of large lake systems. The footprints are preserved as negative epichnia in six wackestones-packstones slabs, housed in the Department of Paleontology, Facultad de Ciencias Naturales, Universidad Nacional de Salta, and with a request for collection numbers in process. Two petrographic thin-sections were made in a slab, indicating the presence of various siliciclastic, carbonatic, and bioclast sedimentary components forming a mixed calcarenite. Some of the slabs show evidence of the development of ESIAM, such as chips, deformed fragments, wrinkled surface, and sedimentary rims associated with the edges of the footprints. All these components were interpreted as corresponding to a mixed environment, in an epicontinental zone, with both terrigenous and marine influence due to intermittent changes. There are at least twelve small footprints, some partially preserved. Their general morphology is between circular and semicircular to irregular. Footprints are larger than, but similar in shape. The impressions of the digits are not clearly distinguished, at least preserving four, arranged parallel to each other, with no claw or digital pad traces. The spatial arrangement is asymmetrical with respect to the midline, with the imprints of the hands located internally and posterior to those of the feet, and corresponding to a jumping or hopping gait with transition to a galloping gait. These characteristics are consistent with the diagnosis of the ichnogenus Brasilichnium, although due to the fragmentary condition and preservational quality of the study material, it has been left in open nomenclature with an uncertain assignment, as Brasilichnium cf. saltatorium. The producer of these footprints is possibly a small mammal, capable of jumping, probably fast, and belonging to one of the representative groups for the southern hemisphere. However, due to different biases in the fossil record, it was not possible to assign it to a particular group. The tracks from Valle del Tonco correspond to the first record of mammalian origin for the Yacoraite Formation and the first from the Maastrichtian age, recording the ichnogenus Brasilichnium from the upper Upper Triassic and extending to the Upper Cretaceous (upper Maastrichtian). In addition, knowledge of the paleobiology of mammals for this period is expanded, providing information on their functionality and locomotion. Mon, 24 Jun 2024 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/11683 2024-06-24T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/11605 Título: Descripción de una mandíbula de ARTRASPOTHERIA (Mammalia, Placentalia) de la formación Cerro Bandera (Mioceno temprano) de la provincia del Neuquén Autor(es): Agüero Méndez, Rocío Ariana Abstract: The Astrapotheria were one of the groups of extinct placental mammals that inhabited South America during part of the Cenozoic era. Along with the Pyrotheria, Xenungulata, Notoungulata, and Litopterna, they represent the native South American ungulates. Here, a complete jaw of Astrapotheria is described, recovered from the Cerro Bandera Formation, west of Plaza Huincul city (Neuquén, Argentina), from levels assigned to the Colhuehuapense age (Early Miocene). The material (MCF-PVPH-375) consists of a jaw with the left incisor 2, alveoli of premolars 3, complete premolar 4-molar 3 series, the angular process, and part of the ascending process. The specimen is assigned to the genus Parastrapotherium due to the following characteristics: a similar dental formula, presence of labial flexion in the molariforms easily observed, presence of a "pillar" in the molars 3, bucco-lingual base of incisor 2 wider than in Astrapotherium. The angular process exhibits crests (possible muscle insertions) not found in Astrapotherium magnum. Some characteristics of MCF-PVPH-375 are more similar to P. martiale and P. crassum more than P. holmbergi, such as dental measurements, greater development of the labial cingulum compared to P. holmbergi, and the presence of a "pillar" absent in P. voghti. MCF-PVPH-375 presents a longitudinal groove on the lingual face of the incisor 2, absent in P. symmetrum. The absence of canines in the specimen studied, prevented its specific assignment. MCF-PVPH-375 confirms the presence of the genus Parastrapotherium for the Cerro Bandera Formation and extends the diversity of astrapotheres for this unit and for the early Miocene in North Patagonia. Fri, 24 May 2024 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/11605 2024-05-24T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/11292 Título: Niveles yesíferos de la formación Sarmiento en el Valle Inferior del Río Chubut. Autor(es): Arcenio, Elías Mario Abstract: The Sarmiento Formation (middle Eocene–lower Miocene) is a continental unit with a broadly geographical distribution in Patagonia central. It is worldwide renowned for their fossil content and by recording climatic and ecological changes linked to regional and global events. In the area of the Chubut river lower valley, the Sarmiento Formation characterize by displaying a succession bearing abundant gypsum, which lacks in detailed sedimentological studies. The presence of gypsum levels in this formation is an unusual feature within their known constituents members cropping out in other parts of the Chubut Province, thus representing an enigma the paleoenvironmental significance of such successions. This study was focused on the characterization of the sedimentological framework of the gypsum-bearing successions and determining the paleoenvironmental factors and potential controls that have influenced the formation of these gypsum deposits. The mapping of the beds bearing gypsum, by the use of ASTER satellite image and spectral analysis techniques restrict to the outcrop area to vicinity of La Angostura locality. In outcrops, distinct gypsum habits and textures were identified. The sedimentological study allowed the definition of four facies associations closely linked to an inland sabkha continental system, with deposits containing gypsum, either immersed in or intercalated with volcaniclastic and clastic deposits. These associations represent the record of the following sedimentary subenvironments: dry mudflat, saline mudflat, shallow saline lake, and perennial saline lake. Additionally, spring mounds were recognized in marginal areas of the system. Variations in gypsum abundance were determined, and various modes of occurrence within the studied sequences were evaluated. The gypsum found in these successions was related to two origins: primary (bottom growth, displacive, and brecciated) and secondary (enterolithic, nodular, cavernous, intergranular replacement). In stratigraphic sense, the studied Sarmiento Formation successions, bearing abundant gypsum, possess a distinctive lithological composition, distinct from those recognized in the various defined members of the unit, that allow suggest the denomination of a new member. Fri, 09 Feb 2024 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/11292 2024-02-09T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/11060 Título: Anatomía de un nuevo ejemplar de tortuga (Pleurodira: Pelomedusoides) de la Formación Portezuelo (Turoniano - Coniaciano), costa norte de Lago Barreales, Neuquén, Argentina Autor(es): Sardá, Mariana Abstract: A new species of turtle (Pleurodira: Pelomedusoides) is introduced, recovered from the Portezuelo Formation (Turonian-Coniacian), Baal Site, on the northern coast of Lago Barreales, Neuquén, Argentina. The Baal Site represents a fluvial paleoenvironment and the biota recorded at the site is similar to that described for the Futalongko Site, also located in Lago Barreales, and for the type locality of the Portezuelo Formation, Sierra del Portezuelo. The main goal of this study is to carry out an anatomical description of the specimen MUC-Pv 2219 to expand the anatomical knowledge of the pleurodiran pelomedusoid turtles from the Cretaceous of Patagonia. MUC-Pv 2219 consists of a nearly complete skull, carapace, and plastron. The skull is articulated with the jaw and part of the hyoid apparatus. It has a length of 45 mm along the midline and a maximum width of 38 mm at the cavum tympani. The jaw is slightly displaced to the left, covering a large part of the ventral view of the skull. The skull exhibits several characteristics that relates it with the Pelomedusoides order within the pleurodiran group, including the presence of a quadratojugal bone and the absence of nasal bones. In lateral view, there is a slight elevation towards the posterior region of the skull. Additionally, the specimen shows an undetermined triangular bone in the jaw, located ventrally to the dentary. The carapace of MUC-Pv 2219 has a length of 210 mm, being suboval in shape, wider in the posterior part than in the anterior. The dorsal convexity reaches its highest point at the fourth pair of costals. The dermal plates are smooth, and the central series is complete, including the nuchal plate, which is wider at the base. The posterior margins show concave curvilinear sutures. The neural series consists of 7 neurals, the first of which is elongated and longer than wide, with an irregular hexagonal shape and shorter posterolateral edges than anterolateral edges. The second neural is quadrangular, with slightly curved lateral margins. The carapace exhibits an anomaly manifested as supernumerary peripheral plates (12 pairs). The plastron measures 183 mm and displays typical features of Pelomedusoides, such as the presence of rounded and equidimensional lateral mesoplastra, a long plastral bridge, and a wide posterior plastral lobe. A comparative analysis reveals that MUC-Pv 2219 constitutes a new taxon of Pelomedusoides, being more closely related to Elkanemys than to Portezueloemys. MUC-Pv 2219 differs from the known taxa in the Portezuelo Formation, such as Portezueloemys patagonica (Pelomedusoides) and Prochelidella portezuelae (Chelidae), thus increasing the diversity of identified turtles in this geological unit. Thu, 23 Nov 2023 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/11060 2023-11-23T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/10874 Título: Micropaleontología de los calcáreos del Cámbrico Inferior de la Formación El Jagüleguito (Río Negro) Autor(es): Villarreal Ochonga, Ramiro Ivan Abstract: The Cambrian Explosion (CE) was a three stage process of diversification that culminated with the appearance of a huge variety of marine animals during the Early Cambrian (541.0 - 521 mya). It is during the second stage of the CE that appeared various invertebrates groups which are currently called Small Shelly Fossils (SSFs) base on their preservation type and possible producers. This fauna has been described world wide, and for that reason they are useful as tools for paleobiogeographic correlation. Nonetheless, descriptions for South American material are made from thin sections, unlike the standard practice (microfossil imaging), with low diversity material (2 genera). In the present paper it’s presented the most diverse southamerican fauna (N=9) to date, obtained from three erratic clasts collected by González et al. 2011 in El Jagüelito Formation, Río Negro, Argentina, based on the hypothesis of a possible affinity with the clasts collected by Wrona 1989, 2003, 2004, 2009 in the antarctic península. The described fauna it’s not diverse enough nor well preserved enough to obtain conclusive results. Mon, 25 Sep 2023 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/10874 2023-09-25T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/10327 Título: Estudio de estructuras bioerosivas asociadas a restos óseos de un plesiosaurio del cretácico superior de antártida. Autor(es): Colileo, Florencia Fernanda Abstract: The study of bioerosive structures recorded in bone remains of marine reptiles constitute a contribution to the paleoecology of sclerobiont assemblages or communities (i.e., organisms that lived associated with this type of material). In addition, to determine the components of these communities from their trace fossils, stages of paleoecological successions can be recognized and thus contribute to the knowledge of the taphonomic history of the bone remains in study. The main objective of this work is to study and recognize macroscopic and microscopic bioerosive structures preserved in the skeletal remains of a plesiosaur (MLP16-I-21-6) recovered from the López de Bertodano Formation (late Maastrichian), Marambio Island, Antarctica. A total of 113 postcranial bone elements belonging to the same individual were identified: 25 vertebral centres, 50 rib fragments, 7 flat bones, 2 pelvic girdle elements, 7 phalanges, and 8 long bones; while some fragments could not be classified. They were observed under a stereoscopic microscope and 3 elements were selected to make histological sections and then they were observed using a polarized light microscope. The material is in good to moderate preservation, with a high degree of fragmentation, and the remains were found in situ, disarticulated but associated. At the macroscopic level, three bioerosive structures were recognized, among which only Trypanites Mägdefrau could be identified. The rest of the traces were classified as Morphotype 1, corresponding to perforations with circular entrances on the surface of the bones with common characteristics between Entobia Bronn and Osedacoides Karl, Brauckmann, and Groening, and, as Morphotype 2 to indeterminate traces, those with certain similarities to those originated by scavengers, although its characterization is not yet conclusive. At the microscopic level, traces with mostly straight tunnels, sometimes branched similar to those caused by endolithic organisms, such as bacteria and fungi, were determined as Morphotype 3 on bone remains. In addition, the presence of pyrite was recognized both in the microperforations as well as in the vascular channels, of which some were modified, indicating an early stage of bone decomposition. The bioerosive traces allowed a preliminary interpretation of some stages of a paleoecological succession. The mobile scavenger stage could be represented by indeterminate tracks similar to those produced by scavengers, although more detailed studies are required to confirm this. The opportunistic enrichment stage could be represented by Osedacoides isp., although this has not yet been confirmed. The modified vascular channels filled with pyrite would be related to the first stages of bacterial bone deterioration or the sulfophilic stage. While the traces assigned to Trypanites isp. and, if Entobia isp. is confirmed, could represent the reef stage. The presence of both macroscopic and microscopic perforations made it possible to record part of the components of the endolithic communities, that lived associated with the bone remains of the studied plesiosaur, indicating that they were exposed for a short time, although long enough, under conditions of low energy and rate of sedimentation, to allow the colonization of these communities. Thu, 22 Sep 2022 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/10327 2022-09-22T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/10192 Título: Caracterización osteológica y ontogenética de un ejemplar juvenil de un saurópodo Titanosaurio Autor(es): Schenardi, Martin Eduardo Abstract: Neuquensaurus australis is a taxon with a long history, it´s one of the first dinosaurs described in Argentina. Even so, only recently a juvenile has been reported for this species. Here I describe the specimenMCS-Pv174-41/66/68/77/78 composed by a vertebral dorsal centrum, vertebral caudal centrum, right scapula and fibula and the left coracoid. These materials were first reported by Zurriaguz et al. in 2019 and identified as N. australis thanks to diagnostics characters in the fibula and the caudal centrum. I compared this specimen with other titanosaurs to validate its taxonomic designation and to identify the variations throughout ontogeny. Phylogenetic analysis results in a polytomy with other saltasaurids, including N. australis, the main differences with other specimens being the lack of some pneumatic indicator features. To estimate its ontogenetic stage, the small size of the material was taken into account. The relationship of the robustness index (IR) was considered to infer an isometric growth, at least in its appendicular skeleton. The absence of fusion at the neurocentral suture is an indication of immaturity, but the complexity of its morphology could be related to later ontogenetic stages, it could also be an indication of a mechanical stress adaptation. Following the ontogenetic morphological stages (MOS) criteria for the axial skeleton, the caudal centrum MCS-Pv174/66 is considered MOS3 and dorsal centrum MCS-Pv174/41 MOS2. This specimen could be considered in a late immature stage, it didn´t reach 60% the full size of the largest N. australis that have been described and it lacks evidence of internal invasion of pneumatic diverticula inside the skeleton. This could mean that the characteristic high pneumatic profile of the group could be reached in the late immature stage or after reaching maturity. Wed, 17 May 2023 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/10192 2023-05-17T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/8650 Título: Registro fósil de la Formación Bajo de la Carpa (Cretácico superior) en el Área natural protegida de Paso Córdoba (Río Negro, Argentina): implicancias paleoecológicas y paleobiológicas e inferencias paleoambientales Autor(es): Fischer, Geraldine Abstract: The Natural Protected Area "Paso Córdoba" (ANPPC) is located at 15 km from General Roca city, province of Río Negro, Argentina, and has aroused scientific interest since the beginning of the last century, with the discovery of the first dinosaur in the area, Antarctosaurus wichmannianus von Huene, 1929. The Mesozoic of ANPPC is represented by three formations belonging to the Neuquén Basin: Bajo de la Carpa (Santonian), Anacleto (middle-lower Campanian), and Allen (upper Campanian-lower Maastrichtian). The Cretaceous continental tetrapod record of these units is notable, highlighting the herpetological repertoire of Bajo de la Carpa Formation, particularly in the region known as “Cañadón de los Cocodrilos” (CDC). To date, this record consists of theropods, snakes, and crocodiles. Despite the previous knowledge, there are no integrative contributions that seek to understand the composition and variability in space, time, and environmental context of this paleofauna. This final degree thesis (TFG) intends to review the vertebrate paleofauna registered at the CDC with an integrating and multidisciplinary perspective, which main objective is to contribut to the knowledge of the paleoecological, paleobiological, and paleoenvironmental context of this area. The components of the paleofauna and the paleoedaphological characteristics of the CDC deposits represent a very interesting case. First of all, the abundance and diversity of the fossil remains is remarkable, particularly the fossil traces of roots and complex structures identified as burrows. One type of them resembles the specimens of the ichnogenus Camborygma isp., associated with freshwater crayfish, while the others correspond to specimens of Daimonelix isp., identified as burrows used for nesting or reproduction of small mammals and reptiles. These ichnotaxons, as well as the burrows, reflect specific behaviors related to the characteristics of the substrate and the anatomy and lifestyle of their producers. To give rise to a population of infaunal decapods that build galleries of moderate complexity associated with plants, such as the CDC specimens, it is inferred close distance to a channel with a high availability of nutrients and oxygen in the substrate and underground. On the other hand, the abundance and distribution of the specimens assigned to Daimonelix isp. allows us to infer that the producers had a fossorial behavior and were gregarious. Based on the topological and architectural attributes of the CDC rhizoliths, two different types of preservation are distinguished: rhizohalos and rhizocretions. The rhizohalos of the lower levels of the paleo-edaphosequence allows us to infer poorly drained paleosols with seasonal saturation, while the levels near the middle section, which contain the highest density of long roots, suggest a seasonally dry environment. Calcareous horizons with a high density of rhizoconcretions indicate an environment with high density of vegetation adapted to drained soils, but with a seasonally high water table or the influence of ephemeral flows. In contrast, the bone remains found at the CDC are poorly preserved, fragmentary, and scarce, most of them concentrated on a single surface. The exception is the materials identified in this work as Notosuchus terrestris Woodward, 1896 from the upper portion of the CDC and two other fragmentary remains identified as Sauropoda indet. Fri, 25 Mar 2022 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/8650 2022-03-25T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/8646 Título: Análisis de huellas avianas del Cretácico Superior del Cañadón del Laberinto (Valle de la Luna Amarillo, Paso Córdoba, Río Negro, Argentina) Autor(es): Urzagasti Torres, Sofía Abstract: Seven slabs bearing avian footprint s, collected from a new ichnosite in the Upper Cretaceous Allen Formation, are here analyzed and discussed. The new ichnosite is ubicated close to Valle de la Luna Amarillo (Paso Córdoba Protected Natural Municipal Area), few kilometers south from the city of General Roca, Río Negro province Argentina. The material was collected both in situ (three slabs) and as loose material (four slabs). Close range, high resolution d igital photogrammetry technique was adopted in order to digitalize specimens and obtain an objective representation of tracks three dimensional morphology. Different softwares were used to take measurements and elaborat e the stratigraphic section within which the ichnosite was found. Five trackways seven pa rtial trackways and 41 isolated tr acks were recognized, giving a total of 74 footprints preserved as concave epirelief Some slabs are characterized on their surfaces by desiccation cracks, ripples marks and different densities of trampling. F ootprints are didactyl, tridactyl or tetradactyl, and some of them retain impressions of digital pads and claw s Based on morphological features, assigned them to two previously reco gnized ichnogenera in the Cretaceous of Argentina, namely cf. Barrosopus isp. and Gruipeda isp. and undetermined avian footprint On the whole, studied avian footprints are related to shorebird producers D ifferent depths of footprints allow inferring dif ferent degrees of sediment moisture at the time of trampling. In addition, behavioral patterns compatible with both walking and foraging have been identified. Based on the sedimentological and paleontological data, it can be inferred that the birds walked over an area subject emersion and desiccation in a floodplain palaeoenvironment. Mon, 21 Mar 2022 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/8646 2022-03-21T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/8645 Título: Tafonomía de mamíferos pleistocenos colectados por Darwin en Punta Alta (Buenos Aires, Argentina): análisis de la colección digitalizada del Museo de historia natural de Londres Autor(es): Nahuel Ruíz, Ernesto Gabriel Abstract: Charles Darwin visited the southwest of the Buenos Aires province during his trip aboard the H.M.S. Beagle in 1832 and 1833, especially the area of Bahía Blanca and its surroundings, making geological and paleontological observations. One of the highlights was the discovery of fossil mammals in Punta Alta. In this degree thesis, the remains of a fossil assemblage from Punta Alta, composed of Equus (Amerhippus) neogeus, Megatherium americanum, Mylodon darwini, Scelidotherium leptocephalum, Toxodon platensis and Toxodon sp., and some fragments of Mammalia ident., were analyzed. The remains, stored and digitized by the staff of the Natural History Museum of London, are available in free access virtual repositories. The purpose of this thesis was to identify various taphonomic attributes using 2D and 3D images in order to verify if the remains were deposited in the context of a fluvial system. The recovered assemblage of mammals presents an NMI = 9 and corresponds to the typical Pleistocene megafauna of the Pampean region of Argentina. In particular, the presence of the lithoptern Macrauchenia patachonica and the equid Equus (Amerhippus) neogeus, indicate a late Pleistocene age for the assemblage. The most represented elements are the skull and the ribs and they are the most affected by weathering processes. The least represented bone elements include vertebrae and astragalus and exhibit the highest degree of abrasion. Most of the remains were disarticulated and incomplete, with the exception of the holotype of S. leptocephalum. In addition, skeletal elements bioeroded by root growth, bacterial activity, and traces of Polychaeta were identified. Some of the remains were impregnated, an attribute that caught Darwin's attention. The identified taphonomic attributes reflect that the bone remains were affected by different processes, both before and after burial. The results obtained are consistent with the interpretation of a fluvial environment. It is considered that some materials were quickly accumulated and buried, while others remained exposed on the surface for a longer period of time and were resedimented. Marine trace fossils suggest that some of the remains were affected by reelaboration. In this context, the association is considered to be composed of both autochthonous (represented only by a nearly complete skeleton of S. leptocephalum) and para-autochthonous specimens. Most of the attributes included in this analysis were observed by Darwin, even though taphonomy had not been defined as a science, which is why his facet as a taphonomist is considered. Mon, 28 Mar 2022 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/8645 2022-03-28T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/8547 Título: Osteología y miología del autopodio posterior en un nuevo dinosaurio Carcharodontosauridae de la Formación Huincul (Cenomaniano-Turoniano, Provincia de Neuquén, Argentina) Autor(es): Palombi, Damiano Abstract: Bipedalism is the form of locomotion that appeared last in evolution and is in terms of biomechanics one of the most complex for a terrestrial animal. The Carcharodontosauridae are among the most impressively sized theropod dinosaurs and possibly are the bipedal and digitigrade animals that have reached the largest body size. However, the foot osteology and myology of the Carcharodontosauridae theropods are poorly studied topics, due to the fragmentary nature of the known materials and the absence of complete hindlimbs in species derived of the clade (Carcharodontosaurinae). The specimen of Carcharodontosauridae MMCh-PV 65, which is the object of this degree thesis, was found in the lower levels of the Huincul Formation (Cenomanian-Turonian), in the locality of Las Campanas, near Villa El Chocón (Neuquén, Argentina). It is a derived representative of the clade and retains complete and exceptionally preserved posterior autopodium elements, representing an opportunity to study novel osteological elements and integrate inferences on soft tissue, musculature, and ligament reconstruction. The detailed study of the posterior metapodium of this family is, as previously stated, an excellent opportunity to investigate the morphofunctional limits linked to the development of gigantism in bipedal dinosaurs. On the basis of the osteological observations, MMCh-PV 65 has a proportionally shorter and more robust foot than phylogenetically related but smaller taxa, such as Allosaurus, Sinraptor and Concavenator. This tendency to have more robust metatarsals, although not cossified together as in the arctometatarsal condition, has led to the development of powerful musculature and extensive ligamentous insertions. Furthermore, given the completeness of the material, the osteological description will help in defining the characteristics of the Carcharodontosauridae foot, potentially solving future taxonomic doubts linked to the metapodium. Fri, 18 Mar 2022 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/8547 2022-03-18T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/8546 Título: Microestructura ósea de Priosphenodon avelasi (Rhynchocephalia: Sphenodontia): implicancias paleobiológicas Autor(es): Cavasín, Sol Aldana Abstract: The rhynchocephalians are one of the groups of vertebrates with fossil representatives which shows a vast taxonomic diversity and worldwide distribution for the Mesozoic era. They have been the subject of studies on their phylogeny and morphology, but those focused on their paleobiology are scarce. In this final degree project, the bone microstructure was studied for eleven elements of the appendicular skeleton belonging to a specimen of Priosphenodon avelasi (MPCA-Pv 308), a Cenomanian-Turonian rhynchocephalian from Río Negro (Argentina) that represents a case of gigantism among Rhynchocephalia. Several aspects of its paleobiology were inquired, such as the sexual and somatic maturation, its relative growth rate, and the minimum age that the individual reached before dying. For this, thin transverse sections were made at the diaphysis level and were analyzed under a binocular optical and petrographic polarized light microscope, comparing the results with studies on other fossil forms, such as Gephyrosaurus and Palaeopleurosaurus, as well as its current relative, Sphenodon. The analyzed samples showed a predominance of pseudolamellar bone in the cortices, a conservative trait among the Rhynchocephalia and an indicator of a relatively low growth rate. However, this rate is not constant, alternating between slow and fast periods, as evidenced by the presence of strongly spaced growth marks which could be linked to the gigantism exhibited in Priosphenodon avelasi. In this respect, P. avelasi resembles more fossil forms than Sphenodon. The elements with a smaller medullary cavity and a higher compaction index were the humerus and the radius, which preserved a higher number of growth marks, evidencing a minimum age of ten years for the specimen MPCA-Pv 308 and proving that they are good bone elements for skeletochronological studies. In the same sense, it was possible to establish that the specimen MPCA-Pv 308 corresponds to a subadult individual, which died after reaching its sexual maturity, but before the attainment of somatic maturity. Wed, 09 Mar 2022 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/8546 2022-03-09T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/6944 Título: Estudio tafonómico de un nuevo dinosaurio saurópodo de la Formación Allen (Cretácico Superior) en el Área Natural Protegida Paso Córdoba, General Roca, Río Negro, Argentina Autor(es): López Rodal, Lisandro Abstract: n this final degree Thesis, the Taphonomic and paleoenvironmental characteristics of a new paleontological site which sauropod dinosaur remains (IIPG-PCor1) from the Allen Formation, Paso Córdoba (Río Negro, Argentina), Upper Cretaceous of the Neuquén Basin, were analyzed. The material consists of fourteen bone elements that include, three articulated cervical vertebrae, eleven fragments of appendicular bones which were disarticulated but associated ossified tendons. The latter have very little integrity and are randomly scattered throughout the site. Two abelisaurid theropod teeth were found close to the vertebrae. Based on sedimentological and stratigraphical data of the studied area, shallow lake systems that transitionally to arid conditions, culminating in a coastal aeolian environment with large transversal dunes are interpreted where the dinosaur remains were found. Two cervical vertebrae present moderate elongation, strongly opystocelic, and with the articular faces below the level of the transverse process, thus the material is classified as an Titanosauria indet. The taphonomic and sedimentological information indicates that the animal would have died on the surface of a dry interdune. There, its carcass was used by scavenging theropods present in the place that dismembered and stole bones, in turn, stepping on them and generating broken pieces. The three articulated vertebrae do not appear to have been moved from the position in which the animal died and are aligned in a Northeast direction, perpendicular to the migration of the adjacent dunes. Weathering covered all of the bones, consistent with a long subaerial exposure time. Signs of wind abrasion were detected, ruling out the possibility that they had been transported. The taphonomic mode in which IIPG-PCor1 was preserved in the Paso Córdoba wind system differs from that observed in the Protocerapts found in the Gobi Desert, Mongolia. Here the animals were preserved in excellent condition, thanks to the fact that they were quickly buried in the dune fields, preserving a final position influenced by the forces acting from the environment. Instead, IIPG-PCor1 showed similarities to current analogues, such as elephants from Tsavo, Kenya, and desert camelids from Abu Dhabi, United Arab Emirates. The latter coincided in having long exposure times to the subaerial environment, where the taphonomic alteration mechanisms acted with greater intensity. Fri, 01 Jan 2021 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/6944 2021-01-01T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/6822 Título: Morfología neurocraneana del Teiidae (Squamata/Lacertilia) Callopistes cf. rionegrensis de la Formación Chichinales (Mioceno temprano), Provincia de Río Negro, Argentina Autor(es): García, Sara Laura Abstract: The Teiidae family represents a lineage of lizards from the New World, with more than nine living genera that are distributed in the American continent and in the West Indies. The group's fossil record dates back to the Middle Triassic, with specimens found in America and Europe. The fossil record of skulls and particularly of neurocranial elements for the clade are extremely scarce, and the latter have been described in a small number of specimens worldwide. Only two taxa are registered in South America, Tupinambis uruguaianensis registered in the Touro Passo Formation, Uruguaiana, Río Grande do soul, Brazil and Callopistes rionegrensis from the Chichinales Formation, General Roca, Río Negro, Argentina, although the latter only preserves part of the parietal and the frontal.In the present Final Degree Project, the most complete fossil neurocranium of a scaly lizard from Argentina is described, assigned Callopistes cf. rionegrensis. The specimen (MPCN-PV754) corresponds to an isolated skull from the Chichinales Formation (early Miocene), in the “Paso Córdoba” National Protected Area, General Roca, Río Negro, Argentina. The material is an almost complete skull whose bony elements, immersed in a sandy matrix, keep their relative anatomical position. In order to avoid any damage to the specimen, no chemical and/or mechanical treatment was carried out. No-invasive computed microtomography was preferred to obtain a high-resolution, three-dimensional model of the skull and neurocranium. To compare the material with an extant representative of the genus, 3D modeling of the skull and neurocranium of the living species Callopistes maculatus was performed. During the comparison between both species, notable differences were observed in the morphology of the neurocrania located especially in: the development of the basal tubercles, the extension of the paraoccipital processes, the development of the ascending process of the supraoccipital, the projection of the basipterygoid processes and the shape of the foramen magnum. The relevance of this study focuses on generating valuable information about the neurocranial morphology of fossil tissues. Although a 3D reconstruction of the endocranial Fri, 01 Jan 2021 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/6822 2021-01-01T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/6795 Título: Estudio de patologías óseas en reptiles marinos mesozoicos de Patagonia y Antártida Autor(es): Mitidieri, Matías Abstract: Paleopathological studies have been used to understand the history of injuries and diseases in the fossil record, and allow deducing the type of skeletal damage that occurs in fossil specimens, its apparent cause, and aspects related to palaeoecology and behavior. The analysis of the pathological characteristics of the Mesozoic marine reptiles of Patagonia and Antarctica, is presented as a vast field of study still scarcely explored, and capable of offering novel information. The main objective of the work is to analyze bone elements of a plesiosaur and a mosasaur recovered from Patagonia and Antarctica which show signs of various paleopathologies. The elements of the specimens were analyzed macroscopically as well as by computerized microtomography. Also, through the photogrammetry technique, a 3D reconstruction of the elements was made, which were then printed using a 3D printer (Creality Ender 3). The first specimen (MML-PV 1305) consists of a cervical vertebra belonging to an adult plesiosaur, recovered from the upper Maastrichtian of Patagonia (Bajo de Santa Rosa, Río Negro). This represents the first report of a bone paleopathology in a marine reptile from Argentina. The macroscopic analysis revealed the presence of a Schmorl nodule accompanied by osteophytes on the lower left edge of the vertebral centrum on the anterior articular face. The analysis of the microtomographs revealed a depression in the central region of the vertebral centrum, followed by an erosion that extended internally to the middle region of it. All these characteristics observed in the specimen are consistent with the diagnosis of a mechanical stress trauma, generated by torsional and compression forces produced by the length of the neck itself or at feeding moments. This pathological condition could generate difficulties in movement and cause recurrent pain in the individual's cervical region. The second specimen (MLP 87-II-7-1) consists of a left scapula belonging to a juvenile mosasaur, recovered from the upper Maastrichtian of Antarctica (Marambio Island), which represents the first report of a bone pathology in a marine reptile from Antarctica . The macroscopic analysis revealed an expansion of the glenohumeral joint, which was deeply eroded and remodeled, and a draining sinus at the level of the scapular neck, which was surrounded by a thin margin of new periosteal bone. Microtomography analysis revealed disorganized trabecular tissue and two draining sinuses. All these characteristics observed in the specimen are consistent with the diagnosis of infectious arthritis. The joint of the scapula and humerus was interrupted by erosion of the glenoid fossa, compromising its normal function. Although not directly related to the death of the mosasaur, this condition may have contributed to reducing its effectiveness in obtaining food or increasing its susceptibility to fatal disease, additional injury, or even predation. The results obtained from the work complement the state of knowledge about current pathologies in extinct forms and their evolutionary prospecting, as well as paleoecological aspects of the organisms studied. Fri, 01 Jan 2021 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/6795 2021-01-01T00:00:00Z http://rid.unrn.edu.ar:8080/handle/20.500.12049/3475 Título: Descripción anatómica, análisis filogenético y morfológico de un cráneo de Odontoceti de la Formación Gran Bajo del Gualicho (Oligoceno superior –Mioceno medio), San Antonio Oeste, provincia de Río Negro, Argentina Autor(es): Fernández Begazo, Estefanía Wed, 17 Oct 2018 00:00:00 GMT http://rid.unrn.edu.ar:8080/handle/20.500.12049/3475 2018-10-17T00:00:00Z