El Lias Superior y el Dogger inferior en Gorgo a Cerbara (Apenino Central): Aspectos bioestratigráficos y sedimentológicos

The present note reports on a detailed survey of a part of the Jurassic - Lower Cretaceous deepening sequence exposed along the Candigliano River west of the hamlet Gorgo a Cerbara in the Umbrian-Marchean Apennines (Italy). The section examined spans the late Pliensbachian to? Bajocian interval, with a major documentary gap in the Toarcian (accounted for by a Neogene fault), and comprises the top of the Corniola Fm. and parts of overlying Bosso Fm. (inclusive of the Mbs. Rosso Ammonitico and Calcari e Marne a Posidonia). Facies of "autochthonous" rock types -mostly lime mudstones and nodular wackestones- invariably imply a deeper-water origin; moreover, inasmuch as gravity-displaced sediment makes up about half the thickness of the section, a depositional setting can be inferred in thc lower reaches or at the base of an unstable slope flanking a structurally- controlled intrabasinal high. The in situ hemipelagic limestones in the upper part of the Corniola Fm. (our lithologic units 1 and 2) have yielded ammonites at 6 separated levels. The ammonite assemblages recovered indicate a late Domerian to earliest Toarcian age. The ammonites collected systematically across the lower nodular limestone unit of the Bosso Fm. (our lithologic unit 3) have enabled the upper Toarcian and part of Aalenian to be recognized and resolved to the zonal and, in certain cases, subzonal level. From the middle Aalenian (Murchisonae Zone p.p.) on, a higher dissolution intensity in the depositional and very shallow burial environment, most likely related to increasing bottom depth, causes the remains of originally aragonitic skeletal components to disappear from the sedimentary record, thus precluding an age control by means of ammonite biostratigraphy.En un punto cercano a la localidad de Gorgo a Cerbara (Apenino Umbro-Marchigiano, Italia) se ha efectuado el levantamiento de una columna estratigráfica correspondiente al intervalo. de tiempo Pliensbachiense superior-Dogger medio dentro del ciclo de profundización jurásico. La sucesión estudiada -en la que se han distinguido 4 tramos litológicos- comprende materiales incluidos, de muro a techo, en las unidades litoestratigráficas "Corniola" (parte terminal) y "Formazione del Bosso" que incluye los Miembros "Rosso Ammonitico" y "Calcari e Marne a Posidonia". Se trata de una secuencia formada en un ambiente de pié de talud ligado a un alto fondo submarino, presentándose el registro sedimentario notablemente expandido debido a la alta proporción de materiales alóctonos. En las hemipelagitas de la parte superior de la "Corniola" (tramos 1 y 2), se ha registrado una sucesión de ammonites representativa del Domeriense superior y de la base del Toarciense. En las calizas nodulosas de la parte inferior de la "Fm. del Bosso" (tramo 3), los ammonoideos registrados han permitido reconocer el Toarciense superior y Aaleniense p.p. y efectuar divisiones a nivel de subzona. A partir del Aaleniense medio (tramo 4), como consecuencia de la creciente intensidad de disolución en ambiente deposicional y diagenético temprano, desaparecen del registro estratigráfico los restos de organismos con esqueleto aragonítico, no siendo por tanto posible la datación de los materiales suprayacentes mediante ammonoideos

Common Avian Infection Plagued the Tyrant Dinosaurs

Background: Tyrannosaurus rex and other tyrannosaurid fossils often display multiple, smooth-edged full-thickness erosive lesions on the mandible, either unilaterally or bilaterally. The cause of these lesions in the Tyrannosaurus rex specimen FMNH PR2081 (known informally by the name 'Sue') has previously been attributed to actinomycosis, a bacterial bone infection, or bite wounds from other tyrannosaurids

A new species of Argyromys (Rodentia, Mammalia) from the oligocene of the valley of lakes (Mongolia): its importance for palaeobiogeographical homogeneity across Mongolia, China and Kazakhstan

We describe a new species of Rodentia (Mammalia), Argyromys cicigei sp. nov. from Toglorhoi (fossil bed TGW-A/2a) in Mongolia and Ulantatal (fossil beds UTL 1 and UTL 7) in China. Its tooth morphology differs from the type species Argyromys aralensis from Akespe in Kazakhstan by smaller size and simpler structures. Argyromys has been assigned in different families of Muroidea, such as Tachyoryctoididae and Spalacidae. However, the presence of common characters indicates a closer relationship of Argyromys with the genera of Cricetidae s.l. (subfamilies Eucricetodontinae; Cricetopinae; Cricetodontinae and Gobicricetodontinae among others) from Asia than with the earliest representatives of Spalacidae or the endemic Tachyoryctoididae. Argyromys cicigei sp. nov. possesses a simple anterocone and anteroconid in the upper and lower first molars, respectively, which is characteristic for Cricetidae s.l. It has a flat occlusal surface in worn specimens; weakly-developed posterolophs; an oblique protolophule and metaloph on the upper molars and it lacks a labial anterolophid on the m1. These traits are also typical of the Oligocene genera Aralocricetodon and Plesiodipus, included in the subfamilies Cricetodontinae and Gobicricetodontinae respectively. The cladistic analysis performed here supports this hypothesis. The clade formed by Argyromys species is grouped with other cricetid taxa (s.l). Spalacids, however, form a different clade, as do the tachyoryctoids. Previous authors state that the Aral Formation (Kazakhstan) should be dated to the Oligocene instead of the Miocene, based on the presence of several taxa. The finds of Argyromys in both regions supports the statement that they are closer in age than previously thought. The occurrence of Argyromys in Kazakhstan, Mongolia and China evidences the biogeographic unity of the Central Asian bioprovince during the Oligocene

Linking the northern Alps with their foreland: The latest exhumation history resolved by low-temperature thermochronology

The evolution of the Central Alpine deformation front (Subalpine Molasse) and its undeformed foreland is recently debated because of their role for deciphering the late orogenic evolution of the Alps. Its latest exhumation history is poorly understood due to the lack of late Miocene to Pliocene sediments. We constrain the late Miocene to Pliocene history of this transitional zone with apatite fission track and (U-Th)/He data. We used laser ablation inductively coupled mass spectrometry for apatite fission track dating and compare this method with previously published and unpublished external detector method fission track data. Two investigated sections across tectonic slices show that the Subalpine Molasse was tectonically active after the onset of folding of the Jura Mountains. This is much younger than hitherto assumed. Thrusting occurred at 10, 8, 6–5 Ma and potentially thereafter. This is contemporaneous with reported exhumation of the External Crystalline Massifs in the central Alps. The Jura Mountains and the Subalpine Molasse used the same detachments as the External Crystalline Massifs and are therefore kinematically coupled. Estimates on the amount of shortening and thrust displacement corroborate this idea. We argue that the tectonic signal is related to active shortening during the late stage of orogenesis