Bioestratigraphy

2009
In L. B. Albright III (ed.), Papers on Geology, Vertebrate Paleontology, and Biostratigraphy in Honor of Michael O. Woodburne. Museum of Northern Arizona Bulletin 65, pp. 569-594. Flagstaff, Arizona.
The mammalian faunal succession in South America is well documented throughout the Eocene from about 47 to 37 Ma. Most Eocene land mammal-bearing deposits occur in Patagonia and in basins of the Antarctic Peninsula, and these have been studied intensely over the last 20 years. The geology of the San Jorge (eastern Patagonia), “Volcanic-Pyroclastic Complex” (western Patagonia), and James Ross (Antarctic Peninsula) basins are here reviewed and their faunal content analyzed. The geochronology of Itaboraian and Riochican South American Land Mammals Ages (SALMAs), usually regarded as late Paleocene, is also discussed. In order to evaluate the similarity between Eocene faunas, a cluster analysis applying the Simpson coefficient was performed using a data matrix with 13 faunas and 228 taxa. The faunas represent both classic and new localities from Antarctica, Patagonia, Mendoza, and central Chile, and we analyzed three taxonomic categories (genus, family, and order) so that faunas lacking common genera could be compared. The analysis supports at least three major clusters. The first, which consists of faunas from western Patagonia (the Paso del Sapo localities) plus Antarctica, seems to fall biochronologically between the Riochican and Casamayoran SALMAs. The second cluster is divided between faunas related to the Casamayoran and those related to the younger Mustersan SALMA. The latest Eocene-earliest Oligocene faunas also group together and are represented by three Tinguirirican faunas plus a fourth younger fauna which seems to be pre-Deseadan (Oligocene).

Se presentan evidencias sedimentológicas y paleobiológicas del Cenozoico superior aflorantes al sur del Alto Pencoso (Serranías Occidentales), correspondientes a las cuencas:
noroeste de Beazley, valle del río Desaguadero y Salina del Bebedero. En Beazley aflora la Formación Las Mulitas (fluvial, Plioceno), caracterizada por los restos fósiles de Notoungulata
y Dasypodidae y cubierta por las formaciones Toro Muerto (aluvial, Pleistoceno medio), Alto Grande (fluvial, Pleistoceno tardío) y Barranquita (eólico, Pleistoceno tardío). Esta última con registros paleontológicos asignados a Glyptodontidae y Macraucheniidae. En la base del arroyo Jarilla aflora la Formación Arco del Desaguadero (fluvial, Pleistoceno tardío) en la que se reconocieron girogonitos de Chara cf. hispida var. major, C. cf. Papillosa y C. hornemannii. Asimismo, en los depósitos costeros de la Salina del Bebedero (fluvio-lacustre, Pleistoceno tardío) se identificaron las conchillas de Chilina mendozana, Heleobia parchappii, Biomphalaria peregrina y Sphaeriidae. Las sedimentitas cretácicas de las Serranías Occidentales fueron la principal área de aporte sedimentario durante el Neógeno, rellenando las depresiones tectónicas
circundantes, con depósitos de planicies aluviales y sistemas fluviales que caracterizan la cuenca de Beazley. Finalmente, las condiciones climáticas globales vinculadas a la última
glaciación en la región cordillerana andina, se manifiestan en los depósitos fluviales arenosos de la cuenca del río Desaguadero, las gravas arenosas calcáreas costeras de la laguna del Bebedero y las arenas y limos eólicos que cubren parcialmente la planicie circundante.
Palabras clave: Cenozoico superior, bioestratigrafía, cuenca Beazley, río Desaguadero, Salina del Bebedero.

In this work, a revision of the mammal assemblages from the local biozones E and F of the Madrid Basin, as well as a study of the faunal turnovers that took place around the middle Aragonian to upper Aragonian boundary, are carried out. This revision has allowed the emendation of some specific attributions and the identification of some taxa previously not cited. A faunal turnover is observed through biozone E, which might be related to global environmental changes. Furthermore, comparisons with the Calatayud-Montalbán Basin have been
performed.

In this work, a revision of the mammal assemblages from the local biozones E and F of the Madrid Basin, as well as a study of the faunal turnovers that took place around the middle Aragonian to upper Aragonian boundary, are carried out. This revision has allowed the emendation of some specific attributions and the identification of some taxa previously not cited. A faunal turnover is observed through biozone E, which might be related to global environmental changes. Furthermore, comparisons with the Calatayud-Montalbán Basin have been performed.

Since the proposition in 1975 of the European Neogene Mammal (MN) scale by Pierre Mein, the amount on taxonomical, stratigraphical and chronological information around Europe has increased exponentially. The stratigraphical schemes of three of the best studied areas for the Lower and Middle Miocene, the Aragonian type area in Spain and the Upper Freshwater Molasse from the North Alpine Foreland Basin in Switzerland, and Bavaria, have been compared. The correlation of their local biostratigraphies has been discussed. Sixteen rodent’s events have been studied and ranked in the three areas according to their local biostratigraphy. This study shows, and quantifies for the first time, the significant asynchronies of the different included rodent events. The MN-system is discussed on the light of those results. In accordance, we propose that it is still useful but only if in a biochronological way, as a sequence of time-ordered reference localities allowing coarse long-distance correlations. In order to obtain better temporal resolution, this system has to be combined with well calibrated to the time scale local biostratigraphies, implementing the information about synchrony and diachrony of mammal events in different areas.

During the Albian siliciclastic rock palynological analyses which correspond to Itapecuru Formation, Parnaiba basin were registered stomata cuticle fragments. These deposits outcrop in the left margin of the Itapecuru River in Querru Village, Itapecuru Mirim city (Maranhao state), where are interbedded sandstones, shales and claystones deposited in lacustrine environment with fluvial influence. Some stomata cuticle fragments represented by anomocytic, laterocytic and stephanocytic complexes are identified. These three complexes suggest development of hydrophyte, hygrophyte, mesophyte and xerophyte plants near of the deposition site. Trichomes of the Y-form and robust or thin simple morphotypes are associated to complexes.