Análisis microscópico y elemental FESEM y Phenom ProX-SEM-EDS de microestructuras parecidas a osteocitos y vasos sanguíneos obtenidas de vertebrados fósiles del Eoceno Messel Pit, Alemania

The Eocene (?48 Ma) Messel Pit in Germany is a UNESCO World Heritage Site because of its exceptionally preserved fossils, including vertebrates, invertebrates, and plants. Messel fossil vertebrates are typically characterized by their articulated state, and in some cases the skin, hair, feathers, scales and stomach contents are also preserved. Despite the exceptional macroscopic preservation of Messel fossil vertebrates, the microstructural aspect of these fossils has been poorly explored. In particular, soft tissue structures such as hair or feathers have not been chemically analyzed, nor have bone microstructures. I report here the preservation and recovery of osteocyte-like and blood vessel-like microstructures from the bone of Messel Pit specimens, including the turtles Allaeochelys crassesculpta and Neochelys franzeni , the crocodile Diplocynodon darwini , and the pangolin Eomanis krebsi . I used a Field Emission Scanning Electron Microscope (FESEM) and a Phenom ProX desktop scanning electron microscope (LOT-QuantumDesign) equipped with a thermionic CeB6 source and a high sensitivity multi-mode backscatter electron (BSE) for microscopical and elemental characterization of these bone microstructures. Osteocyte-like and blood vessel-like microstructures are constituted by a thin layer (?50 nm thickness), external and internal mottled texture with slightly marked striations. Circular to linear marks are common on the external surface of the osteocyte-like microstructures and are interpreted as microbial troughs. Iron (Fe) is the most abundant element found in the osteocyte-like and blood vessel-like microstructures, but not in the bone matrix or collagen fibril-like microstructures. The occurrence of well-preserved soft-tissue elements (at least their physical form) establishes a promising background for future studies on preservation of biomolecules (proteins or DNA) in Messel Pit fossils

La primera tortuga sandownid sudamericana del Cretácico Inferior de Colombia

Sandownids are a group of Early Cretaceous-Paleocene turtles that for several decades have been only known by cranial and very fragmentary postcranial elements. Here I report and describe the most complete sandownid turtle known so far, including articulated skull, lower jaw and postcranial elements, fromthe Early Cretaceous (upper Barremian-lower Aptian, >120 Ma), Paja Formation, Villa de Leyva town, Colombia. The new Colombian sandownid is defined here as Leyvachelys cipadi new genus, new species and because of its almost identical skull morphology with a previously reported turtle fromthe Glen Rose Formation, Texas, USA, both are grouped in a single and officially (ICNZ rules) defined taxon. Phylogenetic analysis including L. cipadi supports once again the monophyly of Sandownidae, as belonging to the large and recently redefined Pan-Chelonioidea clade. The morphology of L. cipadi indicates that sandownids were not open marine turtles, but instead littoral to shallow marine durophagous dwellers. Leyvachelys cipadi not only constitutes the first record of sandowinds in South America, but also the earliest global record for the group

El primer cráneo fósil de Chelus (Pleurodira: Chelidae; tortugas del género Matamata) del Mioceno temprano de Colombia

Here we describe the first fossil skull so far known for the turtle genus Chelus from the early Miocene (~ 16 m.y.), Castilletes Formation, Alta Guajira Peninsula, Cocinetas basin, Colombia. The skull is partially preserved, including most of the basicranium (pteygoid-bassioccipital bones) and the roof elements including the parietal, pterygoid and portions of the squamosal, supraoccipital and the most dorsal quadrate. The skull is preserved in three dimensions, without evidence of crushing, allowing the observation of the internal braincase morphology using microcomputer tomography. Comparisons with the skull of the only extant species for the genus Chelus fimbriata (Matamata turtle) allow us to conclude that for the last 16 million years the morphology of the skull for this genus has remained almost unvarying, with only a slightly higher compression of the most anterior braincase exhibited by the extant species. Due to its fragmentary condition, a more refined identification beyond the genus (Chelus sp.) is not possible; however, the overall skull design indicates that the fossil species could also have had the same ecological and dietary adaptations as its extant relative

'Piel' excepcionalmente conservada en un pez colombiano del Cretácico Inferior

Studies of soft tissue, cells and original biomolecular constituents preserved in fossil vertebrates have increased greatly in recent years. Here we report preservation of ‘skin’ with chemical and molecular characterization from a three-dimensionally preserved caudal portion of an aspidorhynchid Cretaceous fish from the equatorial Barremian of Colombia, increasing the number of localities for which exceptional preservation is known. We applied several analytical techniques including SEM-EDS, FTIR and ToFSIMS to characterize the micromorphology and molecular and elemental composition of this fossil. Here, we show that the fossilized ‘skin’ exhibits similarities with those from extant fish, including the wrinkles after suffering compression stress and flexibility, as well as architectural and tissue aspects of the two main layers (epidermis and dermis). This similarity extends also to the molecular level, with the demonstrated preservation of potential residues of original proteins not consistent with a bacterial source. Our results show a potential preservation mechanism where scales may have acted as an external barrier and together with an internal phosphate layer resulting from the degradation of the dermis itself creating an encapsulated environment for the integument

Pleistocene fossil turtles (Testudinoidea, cryptodira) from the Talara Tar seeps, Peru

A description of Pleistocene fossil turtles discovered in the Talara Tar Seeps, Tablazos deposits of the northern coast of Peru is provided in this paper. The specimens are mostly fragmentary plates of carapaces and plastra of turtles belonging to two cryptodiran families of the superfamily Testudinoidea, identified to genus level based on measurements and comparisons with extant and fossil taxa and identification of mosaic diagnostic features. Turtles of the Geoemydidae family are the most abundant, with fossil remains attributed to Rhinoclemmys (indeterminate species). Less abundant fossil remains belong to the Testudinidae, with specimens attributed to the genus Chelonoidis (indeterminate species). These fossils show that the northern coast of Peru had ecosystems that supported abundant aquatic and terrestrial turtles (tortoises) during the Pleistocene in areas where they are completely absent today. © 2019 Facultad de Ciencias Biologicas, Universidad Nacional Mayor de San Marcos. All rights reserved

New side-necked turtle

19 p. : ill., maps ; 26 cm.Includes bibliographical references (p. 19).A carapace and posterior plastral lobe from the early Cretaceous Valanginian of northeastern Colombia is a new species of the pleurodire Notoemys. It is a pleurodire based on the sutured pelvis and xiphiplastral notch. Notoemys zapatocaensis, n.sp., differs from the other two species of Notoemys, N. oxfordiensis and N. laticentralis, in having a slightly serrated posterior margin, a very small third peripheral, no contact of costal 1 and peripheral 3, and protuberances developed on the pleural and vertebral scale areas. Notoemys zapatocaensis, n.sp., extends the distribution of Notoemys from Argentina and Cuba to Colombia geographically, and from the 156 mya Oxfordian late Jurassic to the 135 mya Valanginian early Cretaceous. Reanalysis based on morphology of the new shell suggests that Notoemys is the sister taxon to the late Jurassic European Platychelys based on the common possession of a very large costovertebral tunnel, tubercle on anterior margin of first thoracic rib, wide, flat thoracic ribs, and a first thoracic centrum that is wider than high

A historical vertebrate collection from the Middle Miocene of the Peruvian Amazon

The Miocene aquatic and terrestrial fossil record from western Amazonia constitute a clear evidence of the palaeoenvironmental diversity that prevailed in the area, prior to the establishment of the Amazon River drainage. During the Miocene, the region was characterized by a freshwater megawetland basin, influenced by episodic shallow-marine incursions. A fossil vertebrate collection from the middle Miocene strata of the Pebas Formation is here studied and described. This historical collection was recovered in 1912 along the banks of the Itaya River (Iquitos, Peru), during a scientific expedition led by two scientists of the University of Zurich, Hans Bluntschli and Bernhard Peyer. Our findings include a total of 34 taxa, including stingrays, bony fishes, turtles, snakes, crocodylians, and lizards. Fishes are the most abundant group in the assemblage (~ 23 taxa), including the first fossil record of the freshwater serrasalmids Serrasalmus, and Mylossoma, and the hemiodontid Hemiodus for the Pebas system, with the latter representing the first fossil be discovered for the entire Hemiodontidae. The presence of a representative of Colubroidea in the middle Miocene of Iquitos supports the hypothesis of arrival and dispersal of these snakes into South America earlier than previously expected. This fossil assemblage sheds light on the palaeoenvironments, and the geographical/temporal range of several aquatic/terrestrial lineages inhabiting the Amazonian region

New insights into the fossil record of the turtle genus Chelus Duméril, 1806 including new specimens with information on cervicals and limb bones

Matamata turtles (Chelus Duméril, 1806) are composed of two extant species, Chelus fimbriata ­Schneider, 1783 and Chelus orinocensis Vargas-Ramírez, Caballero, Morales-Betancourt, Lasso, Amaya, Martínez, Silva-Viana, Vogt, Farias, Hrbek, Campbell & Fritz, 2020, inhabitants of the main freshwater drainages of northern South America. The systematics and palaeobiogeography of Chelus is still unresolved. Here, we describe several new fossil specimens from the Late Miocene of Urumaco (Venezuela) and Tatacoa (Colombia). The fossils are mostly complete, articulated shells that allow reestablishing validity of two extinct taxa, Chelus colombiana Wood, 1976 and Chelus lewisi Wood, 1976. One of the specimens of C. lewisi from Urumaco represents the first record within the genus for which autopodial bones (a left manus) and additional limb bones are preserved together with ashell, demonstrating evolutionary conservatism in limb anatomy for the genus. The specimen comes from the Socorro Formation, representing the earliest so far known record of Chelus for the Urumaco sequence. Additionally, one specimen from Tatacoa is the first fossil for which cervical and pectoral girdle elements are preserved. Phylogenetic analysis supports the existence of two separate clades inside of Chelus, one formed by the extinct species and the other by the extant ones

A Pliocene-Pleistocene continental biota from Venezuela

The Pliocene-Pleistocene transition in the Neotropics is poorly understood despite the major climatic changes that occurred at the onset of the Quaternary. The San Gregorio Formation, the younger unit of the Urumaco Sequence, preserves a fauna that documents this critical transition. We report stingrays, freshwater bony fishes, amphibians, crocodiles, lizards, snakes, aquatic and terrestrial turtles, and mammals. A total of 49 taxa are reported from the Vergel Member (late Pliocene) and nine taxa from the Cocuiza Member (Early Pleistocene), with 28 and 18 taxa reported for the first time in the Urumaco sequence and Venezuela, respectively. Our findings include the first fossil record of the freshwater fishes Megaleporinus, Schizodon, Amblydoras, Scorpiodoras, and the pipesnake Anilius scytale, all from Pliocene strata. The late Pliocene and Early Pleistocene ages proposed here for the Vergel and Cocuiza members, respectively, are supported by their stratigraphic position, palynology, nannoplankton, and 86 Sr/ 88 Sr dating. Mammals from the Vergel Member are associated with the first major pulse of the Great American Biotic Interchange. In contrast to the dry conditions prevailing today, the San Gregorio Formation documents mixed open grassland/forest areas surrounding permanent freshwater systems, following the isolation of the northern South American basin from western Amazonia. These findings support the hypothesis that range contraction of many taxa to their current distribution in northern South America occurred rapidly during at least the last 1.5 million years

Innovación, TIC y gamificación: Aportes desde el saber pedagógico para la educación del siglo XXI

140 páginas. Libro ElectrónicoLas tecnologías de la información y la comunicación se han posicionado en las diferentes esferas de la vida social; desde luego, en el escenario educativo los acontecimientos del año 2020 irrumpieron la cotidianidad de las prácticas pedagógicas generando la necesidad de ampliar la perspectiva de abordaje en lo que refiere a la implementación de TIC. Así, este libro compilado es el resultado de procesos de sistematización de experiencias de tecnologías en procesos educativos en diez instituciones educativas distritales, y de los diferentes diálogos adelantados por el equipo de maestros inspiradores de la línea de TIC y gamificación alrededor de los retos, proyecciones y articulación pedagógica de las tecnologías dentro y fuera del aula.Primera edició