Seven new detrital-zircon U-Pb age analyses along with a compilation of previously published data from Mississippian-Permian sandstones in the Appalachian foreland (total n = 3564) define the provenance of Alleghanian synorogenic clastic wedges, as well as characterize the detritus available to any more extensive intracontinental dispersal systems. The samples are from the cratonward-prograding Mauch Chunk-Pottsville clastic wedge centered on the Pennsylvania salient, the cratonward-prograding Pennington-Lee clastic wedge centered on the Tennessee salient, and a southwestward-directed longitudinal fluvial system along the distal part of the foreland. Grenville-age detrital zircons generally are abundant in all samples; however, ages of the Taconic and Acadian orogenies are dominant in some samples but are minor to lacking in others. Taconic-Acadian ages are dominant in the Mauch Chunk-Pottsville clastic wedge, in parts of the longitudinal system, and in the upper part (above Middle Pennsylvanian) of the Pennington-Lee clastic wedge; but they are minor to lacking in the lower part (Upper Mississippian-Lower Pennsylvanian) of the Pennington-Lee clastic wedge. New Hf isotopic analy ses show a similar distinction between the two clastic wedges, supporting an interpretation of differences in provenance contributions during the early stages of basin filling. U-Pb ages and Hf isotopic ratios also indicate that the Mauch Chunk-Pottsville transverse dispersal fed the northern part of the longi tudinal system. A few samples in the distal southwestern part of the Mauch Chunk-Pottsville clastic wedge and adjacent parts of the longitudinal system have unusually large populations of grains with Superior and Central Plains ages. The relative distance and isolation of these samples from the Cana dian Shield, which is the primary source of Superior and Central Plains zircons, indicates likely recycling from synrift sediment, passive-margin strata, or Taconic-Acadian clastic wedges. Among the lesser components are a few grains with ages that correspond to Iapetan synrift igneous rocks and also to Pan-African-Brasiliano components of Gondwanan accreted terranes. Synorogenic zircons of the Alleghanian orogeny are very rare (seven grains in the total of 3564).

A diverse assemblage of dinosaur and bird tracks from Niobrara County, Wyoming, represents the first vertebrate ichnofauna reported from the bone-rich Lance Formation (Maastrichtian, Upper Cretaceous). The ichnofauna includes a hadrosaur track with skin impressions; three theropod track types, including the tetradactyl track Saurexallopus zerbsti (ichnosp. nov.); a tridactyl dinosaur footprint with a fusiform digit III; possible Tyrannosaurus tracks; four distinctive avian ichnites; and invertebrate traces. The footprints are generally well-preserved and so offer a unique insight into the ecology of a small river valley during the Maastrichtian.Saurexallopus zerbsti ichnosp. nov. from the Lance is similar to Saurexallopus lovei recently reported from the Maastrichtian, Harebell Formation, of northwestern Wyoming, but is represented by much better material, facilitating amendment of the ichnogenus. Skeletal equivalents for Saurexallopus are not currently known. Similarly, the tridactyl track with fusiform digit III is similar to footprints reported from the coeval Laramie Formation of Colorado and may also be similar to ichnogenus Ornithomimipus from the Edmonton Group of Alberta (though not necessarily of ornithomimid affinity). The hadrosaurian track with the skin impression is reminiscent of a similar ichnite reported from the Maastrichtian, St. Mary River Formation in Alberta, which is herein named Hadrosauropodus langstoni as part of a reassessment of Cretaceous ornithopod track ichnotaxonomy. Such correlations demonstrate the utility of tracks for local or regional biostratigraphy (palichnostratigraphy) in western North America. It is also clear that tracks add to our knowledge of the composition and distribution of dinosaurian and avian components of Maastrichtian faunas. In particular the bird tracks indicate a diversity of at least four species, one of which was a semi-palmate form, hith

Cretaceous dinosaur footprints discovered in the J Sandstone of the South Platte Formation (Dakota Group) in Colorado and the St. Mary River Formation of southwestern Alberta exhibit the first reported foot pad skin impressions of large ornithopods. The Canadian tracks occur as sandstone casts preserved in mudstones, whereas the Colorado tracks are natural impressions in a sandstone bed overlain by shale. The South Platte Formation tracks occur as impressions in a widespread "dinoturbated" sandstone bed representing low-gradient, delta plain -coastal plain facies assemblages associated with the upper member of the group, the J Sandstone. Only one of the many iguanodontid trackways exhibits good skin impressions.The St. Mary River Formation palaeoenvironment is interpreted as an anastomosed fluvial system that flowed northeast over a low-gradient floodplain from Montana. Footprints, often preserved in trackways, were left as dinosaurs walked across lake and marsh sediments that were relatively well drained or in various stages of dewatering. The quality of preservation is variable, depending on the properties of the substrate, and only one hadrosaur footprint includes clear casts of skin patches on the bottom of the footprint. Similar track-rich facies assemblages, representing lowland coastal plain and deltaic environments, are found in both the Lower (Gething Formation, British Columbia) and Upper Cretaceous (Mesa Verde, Colorado) successions of western North America. Few substrates of these depositional environments were suitable for the preservation of skeletal remains, so the information derived from tracks is palaeontologically significant.Les empreintes de pas de dinosaures crCtacCs, trouvCes dans le grks J de la Formation de South Platte (Groupe de Dakota) du Colorado et dans la Formation de St. Mary River du sud-ouest de I'Alberta, sont les premikres empreintes dtcrites de I'Cpidexme des pattes de grandes omithopodes. Les traces dans le gisement canadien apparaissent sous forme d'un moule de gres prCservC dans des mudstones, tandis que les traces du gisement du Colorado sont des empreintes naturelles dans une couche de gres recouverte par un shale. Les traces dans la Formation de South Platte sont reprksentkes par des empreintes dans un gres << piCtinC par les dinosaures n, qui est largement rkpandu, qui fait partie des assemblages de facies de plaine deltaique -plaine littorale avec faible pente, et qui est associC au membre supCrieur du groupe appelC le grks J. Les empreintes claries de 1'Cpiderme n'ont kt6 trouvkes que dans une parmi les nombreuses pistes CtudiCes.Le paltomilieu de la Formation de St. Mary est interprCtC comme Ctant celui d'un systeme fluviatile, anastomosC, qui coulait vers le nord-est sur une plane d'inondation faiblement inclinCe, h partir du Montana. Les empreintes des pas, frequemment alignCes en pistes, ont Ct C produites lorsque les dinosaures marchaient au travers les lacs et les skdiments de markcages relativement bien drainCs ou a divers stades d'asskchement. L'ttat de prCser...

No abstract

Triassic sediments exposed along the south shore of New Brunswick, near St. Martins, were deposited primarily by a series of alluvial fans prograding eastward from the western margin of the Fundy half graben and are interbedded with fluvial conglomerates deposited by an axially flowing river system. The sediments are divisible into three formations, which are described here formally for the first time. These are, from base to top, the Honeycomb Point, Quaco, and Echo Cove formations. The basal Honeycomb Point Formation consists of approximately 990 m of red beds exposed in several fault blocks. The western outcrops consist of coarse breccias of the proximal fan, the Browns Beach Member, which fines eastward into sheetflood deposits of the mid- to distal fan, the McCumber Point Member. Both units contain eolian sands that indicate paleowind direction from the northeast. These are overlain by fluvial conglomerates of the Quaco Formation, 190–300 m thick, which were deposited by a large, braided river system that flowed north along the axis of the graben. Renewed growth of the alluvial fans led to the deposition of the Echo Cove Formation, 850–1300 m thick, on the conglomerates. The coarsest breccias are found in the westernmost exposures, the Stony Brook Member, and along the coast the formation is divided into the basal redbed unit, the Berry Beach Member, which grades into green beds of the Fownes Head Member, which in turn is overlain by the red beds of the Melvin Beach Member. Pollen recovered from the upper portion of the Fownes Head Member places the unit in the mid-Carnian (and possibly Ladinian).

No abstract

No abstract

No abstract