Late Jurassic ichthyosaurs from the Neuquén Basin,Argentina

Late Jurassic ichthyosaurs are well represented in the Tithonian of the Neuquén Basin, in northwestern Patagonia, Argentina. Most of the ichthyosaur material from the Neuquén Basin was originally identified as Ophthalmosaurus. Recently, the new ichthyosaur genus Caypullisaurus was described, based on an almost complete mature specimen from Cerro Lotena. Some material previously referred to Ophlhalmosaurus has been referred to the new genus. However, both genera are present in the Tithonian of the Neuquén Basin. The discovery of an articulated forefin in Cajón de Almanza (near Loncopue, Neuquén) confirms the presence of Ophthalmosaurus in the uppermost Tithonian of the Neuquén Basin.     

The first specimen of Archaeopteryx from the Upper Jurassic Mörnsheim Formation of Germany

From an initial isolated position as the oldest evolutionary prototype of a bird, Archaeopteryx has, as a result of recent fossil discoveries, become embedded in a rich phylogenetic context of both more and less crownward stem-group birds. This has prompted debate over whether Archaeopteryx is simply a convergently bird-like non-avialan theropod. Here we show, using the first synchrotron microtomographic examination of the genus, that the eighth or Daiting specimen of Archaeopteryx possesses a character suite that robustly constrains it as a basal avialan (primitive bird). The specimen, which comes from the Mörnsheim Formation and is thus younger than the other specimens from the underlying Solnhofen Formation, is distinctive enough to merit designation as a new species, Archaeopteryx albersdoerferi sp. nov., but is recovered in close phylogenetic proximity to Archaeopteryx lithographica. Skeletal innovations of the Daiting specimen, such as fusion and pneumatization of the cranial bones, well vascularized pectoral girdle and wing elements, and a reinforced configuration of carpals and metacarpals, suggest that it may have had more characters seen in flying birds than the older Archaeopteryx lithographica. These innovations appear to be convergent on those of more crownward avialans, suggesting that Bavarian archaeopterygids independently acquired increasingly bird-like traits over time. Such mosaic evolution and iterative exploration of adaptive space may be typical for major functional transitions like the origin of flight.     

Cieneguiticeras, a new genus of Tithonian oppeliids (Ammonoidea, Late Jurassic)

The new genus Cieneguiticeras, assigned to the family Oppeliidae, is described on the basis of Andean lower-middle Tithonian ammonites from Arroyo Cieneguita, west-central part of the Neuquén-Mendoza Basin, Argentina. The macroconchs are closely homoeomorphic with Neochetoceras Spath and the microconchs have a ‘glochiceratid’-type morphology. The stratigraphic range of Cieneguiticeras nov. gen. includes the lower and middle Tithonian by means of a succession of two or three species which are interpreted as members of a phyletic lineage. Ammonites from the Tithonian of Cuba, Mexico and France are more or less confidently included in this new genus.     

ISOPOD TRACKWAYS FROM THE CRAYSSAC LAGERSTÄTTE, UPPER JURASSIC, FRANCE

Abstract:  Well-preserved arthropod trackways are described from the laminated limestones of the Crayssac Lagerstätte (south-west France, Lower Tithonian). They occur in sediments deposited in the temporary coastal mudflats of intertidal to supratidal zones. The trackways are referred to Pterichnus isopodicus isp. nov., and are interpreted as the locomotion traces of isopods. Different trackway morphotypes are recognized and clearly resulted from variations in the original consistency of the sediment. Sinuous trackways may correspond to vagrant activity on wet mud whereas numerous straight ones indicate a more rapid crawling on a soft-to-firm substratum (e.g. tidal flat during emersion). The preferred orientation of trackways indicates that isopods were crawling in a direction perpendicular to shoreline as a result of possible taxis induced by sediment wetness and/or by a migratory behaviour controlled by tidal rhythm. Unusually long emergence of the sediments may have favoured the preservation of dense networks of trackways. An isopod identity is supported by the general morphology of the tracks and the association of trackways with isopod body fossils. Archaeoniscus , which occurs abundantly in Late Jurassic deposits of England and France, was probably the trace-maker.     

Révision taxonomique du genre d'ammonite téthysien Simoceras et création d'un nouveau genre Volanoceras (Ammonitina,Simoceratidae)

The type-species of the genus SimocerasZittel isS. biruncinatum (Qu.). This genus includes the species-group biruncinatum (Qu.) — admirandum (Zitt.). The new genus Volanoceras is created for the volanense (Opp.) species-group which is excluded from the genus Simoceras.     

Caribbean Lower Tithonian ammonites from central-east Mexico

Imlay's ammonite species Paradontoceras butti and Paradontoceras antilleanum are first reported from central-east Mexico under precise stratigraphic control. Mexican and Cuban ammonites referred to these species have been studied and proved to have been gathered from a relatively limited area within the southern paleomargin of the north American Plate, which embraces eastern Mexico and north-western Cuba. The palaeontological examination, the multivariate analysis conducted on Mexican and Cuban data, the precise biostratigraphic and biogeographic control support the reinterpretation of Imlay's species P. antilleanum and P. butti. The latter has been designated the single, valid nominal species-level taxon which comprises the two species proposed by Imlay. The new genus Housaites has been created since the taxon Butticeras Houša is not available for taxonomic nomenclature. Housaites butti (Imlay) is upper Lower Tithonian (Semiforme/Verruciferum Zone of the Tethyan standard) in Mexico. The stratigraphic range in Cuba is not conclusively known.     

Tithonian ammonoid biostratigraphy in eastern Himalayan Tibet

The Tithonian and Lower Berriasian sediments in the eastern Himalayas of Tibet contain an extensive sequence of ammonoid fauna. New collections in situ through the Lanongla, Pure, Gucuo and Jiapeila sections have facilitated a major revision of the ammonoid assemblages. Probably due to depositional facies segregation, the Belemnopsis galoi-bearing beds can be regarded as the oldest Tithonian sediments in which the basal Tithonian ammonoid Kossmatia is not present. The Lower Tithonian includes the Virgatosphinctes-Aulacosphinctoides and Uhligites-Aulacosphinctes assemblages; the Upper Tithonian includes the Haplophylloceras pingue, Blanfordiceras wallichi and Haplophylloceras strigile-Corongoceras-Himalayites assemblages. The Spiticeras assemblage is suggested to be from the Lowermost Berriasian. The new ammonoid assemblages at well-defined levels in Himalayan Tibet provide some crucial links for correlation with other regions of the SW Pacific domain where these ammonoid genera have been widely distributed.     

Fishes from the Akkuyu Formation (Tithonian),Western Taurus,Turkey

Two fragmentary fishes are described from theUpper Jurassic (Tithonian) Akkuyu Formation of the Akseki region in the western Taurus (Turkey). Both are determinable, one as a caudal fin of an ichthyodectiform teleost, either Thrissops or Allothrissops, the other as a coelacanthid coelacanth, cf. Undina. This discovery extends the geographic range of these taxa and draw attention to the possibility of collecting a more extensive fish fauna from the region.