Oligocene larger foraminifera from United Arab Emirates,Oman and Western Desert of Egypt

An early Oligocene (Rupelian) diagnostic larger foraminiferal assemblage is described and illustrated from marls and limestones of the Asmari Formation, at Jabals Hafit and Malaqet in the UAE. An equivalent assemblage is identified in the mudstones of the Tahwah Formation, Wadi Suq, Oman. Although Nummulites intermedius (D'Archiac 1846) and N. fichteli are fully synonymous (e.g. Roveda 1970; Schaub 1981; Sirel 2003), in this study both species are biometrically differentiated, distinct and both names are valid. N. fichteli Michelotti 1841, N. intermedius (D'Archiac 1846) and N. emiratus n. sp., which are index for the early Oligocene (Rupelian), and they are replacing each others competitively and environmentally.

The presence of Blondeauina bouillei n.gen., N. emiratus n.sp., N. intermedius, N. fichteli, Planoperculina complanata (Defrance 1822) and Austrotrillina asmariensis Adams 1968 ascribed the section of the Asmari Formation to the early Oligocene (Rupelian). The studied marls and limestones were deposited in outer and inner shelf environments, respectively. The Asmari Formation in the area studied consists mainly of marl in its lower portion and reefal limestone in its upper part, indicating a major marine regression. The Tahwah Formation in Oman is composed of bioturbated silty and muddy marls and is a facies equivalent to the Asmari Formation marls. The Asmari Formation facies change probably relates to a mid-Oligocene fall in global sea level.

In this study, the Dabaa Formation, a subsurface unit of late Eocene–Oligocene marine shales in the north Western Desert of Egypt, was chosen to correlate with the Oligocene of Emirates and Oman. The Dabaa Formation comprises Spiroclypeus ornatus (Henson 1937) and Eulepidina dilatata (Michelotti 1861). The environment of deposition was inner shelf to littoral, which become estuarine towards the top in many areas. This Oligocene Dabaa sequence is correlatable with Wadi El Arish sequence recently discovered by Kuss and Boukhary (2008) from Risan Aneiza, Northern Sinai, Egypt.     

Dinosaur remains from the ‘Botucaraí Hill’ (Caturrita Formation), Late Triassic of south Brazil,and their stratigraphic context

Vertebrate fossils recovered from sites nearby the Botucaraí Hill and Candelária (Caturrita Formation) depict a diverse Late Triassic tetrapod fauna from south Brazil. These records are of key importance to the biostratigraphy of the upper sections of the Rosario do Sul Group. A lithological and biostratigraphic survey on the main fossil localities of the Botucaraí Hill area confirms the occurrence of the lower Hyperodapedon and the upper Riograndia Assemblage Zones in the region, the latter yielding early saurischians. In this paper, three incomplete dinosaur specimens, an isolated sacral vertebra, an articulated left pubis–ischium and an isolated right ischium, from the ‘Botucaraí Hill’ site are described. A comparative survey suggests that these specimens have sauropodomorph affinities, but probably more primitive than typical ‘prosauropods’ from the Norian-Early Jurassic. Regardless of the phylogenetic position of Guaibasaurus as theropod or sauropodomorph, their occurrence in the Caturrita Formation, which also yielded ‘core prosauropods’ from the Santa Maria region, suggests either the survival of early members of the clade with more derived ‘prosauropods’ or that heterochronous faunas are sampled from that stratigraphic unit.     

On the earliest record of Cretaceous tyrannosauroids in western North America: implications for an Early Cretaceous Laurasian interchange event

The sudden appearance of Asian dinosaur clades within Lower Cretaceous strata of western North America has long been recognised as a biotic dispersion event related to initial establishment of a Beringian land bridge. To date, uncertainty exists regarding the timing of the Early Cretaceous Laurasian interchange event (EKLInE) and the pattern of associated biotic dispersal. Here, we report a tyrannosauroid premaxillary tooth (FMNH PR 2750) from the Cloverly Formation, Wyoming, USA, that pushes back the earliest Cretaceous record of the clade in North America. Although fragmentary, the tooth is consistent with mounting evidence for a pre-108 Ma initiation of EKLInE and earliest Albian emplacement of Beringia. Previous authors have considered the Aptian/Albian of western North America a depauperate dinosaur fauna, characterised by regional extinction and diversity decline. Documentation of Albian tyrannosauroids in the region indicates a more dynamic ecosystem than previously appreciated and marks an early start to faunal mixing between immigrant and endemic dinosaur clades. Finally, we find that the enamel microstructure of FMNH PR 2750 conforms to the morphotype of tyrannosaurids, yet exhibits poor columnar differentiation. This morphology bolsters prior interpretations on the phylogenetic utility of enamel microstructure and suggests a trend of increasing enamel complexity within Tyrannosauroidea.     

First titanosaur (Saurischia,Sauropoda) axial remains from the Uberaba Formation,Upper Cretaceous,Bauru Group,Brazil

The Adamantina and Marília formations are considered to be the richest vertebrate-bearing units in the Bauru Group, Upper Cretaceous, Brazil. In contrast, the fossil content from the Uberaba Formation, which only outcrops in Minas Gerais State, is scarce and poorly understood. In this essay the first taxonomically informative titanosaur remains unearthed from this unit are reported. They comprise anterior caudal vertebrae from two different individuals corresponding to a probably basal titanosaur (CPP-360) and a derived titanosaur (CPP-217). Although these remains can be clearly distinguished from other titanosaurs on the basis of their unique association of characteristics like the presence of mildly procoelous centra, lateral pits in the anterior caudal vertebrae, and prezygapophyses with a dorsal protuberance in anterior caudals in CPP-360 and the presence of strongly developed prespinal, spinopostzygapophyseal and centropostzygapophyseal laminae in CPP-217, more complete materials are needed to propose them new names.     

Maastrichtian facies succession and sea-level history of the Hossein-Abad,Neyriz area,Zagros Basin

The Maastrichtian shallow-water carbonate platform (Tarbur Formation) is described from outcrop in southwest Iran. It is characterised by eight microfacies types, which are dominated by larger foraminifera, rudist debris and dasycladacean algae. They are grouped into four distinct depositional settings: tidal flat, lagoon, barrier and open marine. The depositional settings include stromatolitic boundstone of tidal flat, peloidal dasycladacean miliolids wackestone and peloid bioclastic imperforate foraminifera wackestone of restricted lagoon, Omphalocyclus miliolids bioclast packstone–grainstone and miliolids intraclast bioclast packstone–grainstone of open lagoon, rudist bioclast grainstone of inner-platform shoals and rudist bioclast floatstone–rudstone and bioclastic wackestone of open-marine environments.

The facies and faunal characters are typical of a ramp-like open shelf. The lack of reef-constructing organisms resulted in a gently dipping ramp morphology for the margin and slope. On the basis of facies analysis, three depositional sequences (third order) are defined.     

Structural characterization of curved interfacial films of T and S-LJ fluid by molecular simulation

The structure of curved interfacial films formed by the adsorption of the simple T and S-LJ fluid between two structureless planar surfaces was investigated by the means of Grand Canonical Ensemble Monte Carlo (GCEMC) simulation. Our specific aim was to study the formation of a semi-spherical droplet on the planer surface. The surfaces were simulated using Steele's U 10-4-3 ( z ) potential. The droplet was created by truncating the surface potential with a sharp circular cut-off. The remainder of the surface consists of an infinitely hard reflective wall, with rectangular periodic boundary conditions (PBCs) in the xy -plain. This system produced three distinct stages in the structure adsorbed curved films, over an increasing range of relative pressure, p ': at low p ' the film consists of circular monolayers with decreasing radii the farther from the surface; at mid range p ', the film closes to semi-spherical interface with a cap of liquid-like fluid at the pole, at p ' low p ' the film consists of circular monolayers with decreasing radii the farther from the surface; at mid range p ', the film closes to semi-spherical interface with a cap of liquid-like fluid at the pole, at p ' above the saturated vapour pressure of the bulk fluid, a liquid-gas (LG) film of cylindrical symmetry forms an "hour-glass" interface bridging the droplets on opposite surfaces.