Some recent papers with free pdfs:
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Gabriel AndrÃs Casal, Adriana MÃnica Nillni, Mauro NicolÃs Valle, Jorge Ezequiel GonzÃlez Svoboda, MarÃa Celina Tiedemann, Helena Ciapparelli, Lucio Manuel Ibiricu & Marta Mabel Luiz (2019)
FosildiagÃnesis en restos de dinosaurios preservados en depÃsitos fluviales de la FormaciÃn Lago Colhuà Huapi (CretÃcico Superior). Cuenca del Golfo San Jorge, Argentina.
[Fossil-diagenesis in dinosaurs remains preserved in fluvial deposits of the Lago Colhuà Huapi Formation (Upper Cretaceous), Golfo San Jorge Basin, Argentina]
Andean Geology 46(3): (advance online publication)
http://www.andeangeology.cl/index.php/revista1/article/view/3212/pdf
New sedimentological and fossil-diagenetic information from remains of four dinosaurs is herein provided. The fossil material was preserved in deposits of different fluvial sub-environments from the middle section of the Lago Colhuà Huapi Formation, Golfo San Jorge Basin. In all the studied cases, the bone structure originally constituted by hydroxyapatite was modified by ionic substitution to francolite. The fossil remains contained in fine lithoarenites with high clay minerals content, affected by lithostatic compression, exhibit plastic deformation and intense fracturing which affected the bone microstructure. The francolite presents cavernous texture with high crystallinity index and a lower carbonate content, evidencing processes of mineral dissolution in an acidic environment. The hematite is present as crusts and nodules on the surface of the bones and internally at the edges of the vascular channels. It is related to the precipitation of iron oxide in well oxygenated areas with fluctuating water table. The permineralization of the vascular channels with hematite and well-developed crystals of fluorapatite of neoformation, would have occurred during the early diagenesis. By contrast, the fossil remains contained in coarse lithoarenites with scarce clay minerals, have been less affected by lithostatic compression and are better preserved. The francolite exhibits a massive texture with a lower index of crystallinity and higher carbonate concentration. The permineralization of the vascular channels with hematite and well-developed crystals of calcite would have occurred in an alkaline environment during the late diagenesis. In the four study-cases it could be determined that the crystallinity indexes of the francolite and the carbonate content, display a positive correlation with the relative increase of fluorine content and the fragility of the fossil remains.
Therefore, the sedimentological and fossil-diagenetic studies, in particular the permineralization processes in the vascular channels, enhance our understanding of the physical and chemical conditions that prevailed during the lithification and fossilization of the fossil remains in different fluvial sub-environments from the Lago Colhuà Huapi Formation.
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Free pdf:
Pellornis mikkelseni is an early gruiform from the latest Paleocene-earliest Eocene Fur Formation of Denmark. At approximately 54 million years old, it is among the earliest clear records of the Gruiformes. The holotype specimen, and only material thus far recognised, was originally considered to comprise a partial postcranial skeleton. However, additional mechanical preparation of the nodule containing the holotype revealed that the skeleton is nearly complete and includes a well-preserved skull. In addition to extracting new information from the holotype, we identify and describe two additional specimens of P. mikkelseni which reveal further morphological details of the skeleton. Together, these specimens show that P. mikkelseni possessed a schizorhinal skull and shared many features with the well-known Paleogene Messelornithidae ("Messel rails"). To reassess the phylogenetic position of P. mikkelseni, we modified an existing morphological dataset by adding 20 characters, four extant gruiform taxa, six extinct gruiform taxa, and novel scorings based on the holotype and referred specimens. Phylogenetic analyses recover a clade containing P. mikkelseni, Messelornis, Songzia and crown Ralloidea, supporting P. mikkelseni as a crown gruiform. The phylogenetic position of P. mikkelseni illustrates that some recent divergence time analyses have underestimated the age of crown Gruiformes. Our results suggest a Paleocene origin for this important clade, bolstering evidence for a rapid early radiation of Neoaves following the end-Cretaceous mass extinction.Â
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Ivo R. Horn, Yvo Kenens, N. Magnus Palmblad, Suzanne J. Van der Plas-Duivesteijn, Bram w. Langeveld, Hanneke J. M. Meijer, Hans Dalebout, Rob J. Marissen, Anja Fischer, F. B. Vincent Florens, Jonas Niemann, Kenneth F. Rijsdijk, Anne S. Schulp, Jeroen F. J. Laros and Barbara Gravendeel Â(2019)
Palaeoproteomics of bird bones for taxonomic classification.
Zoological Journal of the Linnean Society 186(3): 650â665
doi:
https://doi.org/10.1093/zoolinnean/zlz012https://academic.oup.com/zoolinnean/article/186/3/650/5470657We used proteomic profiling to taxonomically classify extinct, alongside extant bird species using mass spectrometry on ancient bone-derived collagen chains COL1A1 and COL1A2. Proteins of Holocene and Late Pleistocene-aged bones from dodo (Raphus cucullatus) and great auk (Pinguinus impennis), as well as bones from chicken (Gallus gallus), rock dove (Columba livia), zebra finch (Taeniopygia guttata) and peregrine falcon (Falco peregrinus), of various ages ranging from the present to 1455 years old were analysed. HCl and guandine-HCL-based protein extractions from fresh bone materials yielded up to 60% coverage of collagens COL1A1 and COL1A2, and extractions from ancient materials yielded up to 46% coverage of collagens COL1A1 and COL1A2. Data were retrieved from multiple peptide sequences obtained from different specimens and multiple extractions. Upon alignment, and in line with the latest evolutionary insights, protein data obtained from great auk grouped with data from a recently sequenced razorbill (Alca torda) genome. Similarly, protein data obtained from bones of dodo and modern rock dove grouped in a single clade. Lastly, protein data obtained from chicken bones, both from ancient and fresh materials, grouped as a separate, basal clade. Our proteomic analyses enabled taxonomic classification of all ancient bones, thereby complementing phylogenetics based on DNA.