The Upper Cretaceous (middle-late Campanian) Wahweap Formation of southern Utah contains the olde... more The Upper Cretaceous (middle-late Campanian) Wahweap Formation of southern Utah contains the oldest diagnostic evidence of ceratopsids (to date, all centrosaurines) in North America, with a number of specimens recovered from throughout a unit that spans between 81 and 77 Ma. Only a single specimen has been formally named, Diabloceratops eatoni, from the lower middle member of the formation. Machairoceratops cronusi gen. et sp. nov., a new centrosaurine ceratopsid from the upper member of the Wahweap Formation, is here described based on cranial material representing a single individual recovered from a cal-careous mudstone. The specimen consists of two curved and elongate orbital horncores, a left jugal, a nearly complete, slightly deformed braincase, the left squamosal, and a mostly complete parietal ornamented by posteriorly projected, anterodorsally curved, elongate spikes on either side of a midline embayment. The fan-shaped, stepped-squamosal is diagnostic of Centrosaurinae, however, this element differs from the rectangular squamosal in Diabloceratops. Machairoceratops also differs in the possession of two anterodorsally (rather than laterally) curved epiparietal ornamentations on either side of a midline embay-ment that are distinguished by a posteromedially-oriented sulcus along the entire length of the epiparietal. Additionally, the parietosquamosal frill is lacking any other epiossifications along its periphery. Machairoceratops shares a triangular (rather than round) frill and spike-like epiparietal loci (p1) ornamentation with the stratigraphically lower Diabloceratops. Both parsimony and Bayesian phylogenetic analyses place Machairoceratops as an early-branching centrosaurine. However, the parsimony-based analysis provides little resolution for the position of the new taxon, placing it in an unresolved polytomy with Diabloceratops.
Objectives: To quantify personal time-weighted average respirable dust and quartz exposure on a s... more Objectives: To quantify personal time-weighted average respirable dust and quartz exposure on a sandy, a sandy loam, and a clay soil farm in the Free State and North West provinces of South Africa and to ascertain whether soil type is a determinant of exposure to respirable quartz.
USA: American Association of Petroleum …, Jan 1, 2009
The Wahweap Formation (Fm) is a ~400 m thick package of fluvial/estuarine channel sandstones and ... more The Wahweap Formation (Fm) is a ~400 m thick package of fluvial/estuarine channel sandstones and floodbasin mudstones deposited adjacent to the Western Interior Seaway (WIS) during the Late Cretaceous. It contains four informal members: the lower, middle, upper and capping sandstone members. This study aims to test existing tectono-eustatic basin models and reconstruct the sedimentary and tectonic history of the southern Cordilleran foreland basin during this important interval.
The Upper Cretaceous (middle-late Campanian) Wahweap Formation of southern Utah contains the olde... more The Upper Cretaceous (middle-late Campanian) Wahweap Formation of southern Utah contains the oldest diagnostic evidence of ceratopsids (to date, all centrosaurines) in North America, with a number of specimens recovered from throughout a unit that spans between 81 and 77 Ma. Only a single specimen has been formally named, Diabloceratops eatoni, from the lower middle member of the formation. Machairoceratops cronusi gen. et sp. nov., a new centrosaurine ceratopsid from the upper member of the Wahweap Formation, is here described based on cranial material representing a single individual recovered from a cal-careous mudstone. The specimen consists of two curved and elongate orbital horncores, a left jugal, a nearly complete, slightly deformed braincase, the left squamosal, and a mostly complete parietal ornamented by posteriorly projected, anterodorsally curved, elongate spikes on either side of a midline embayment. The fan-shaped, stepped-squamosal is diagnostic of Centrosaurinae, however, this element differs from the rectangular squamosal in Diabloceratops. Machairoceratops also differs in the possession of two anterodorsally (rather than laterally) curved epiparietal ornamentations on either side of a midline embay-ment that are distinguished by a posteromedially-oriented sulcus along the entire length of the epiparietal. Additionally, the parietosquamosal frill is lacking any other epiossifications along its periphery. Machairoceratops shares a triangular (rather than round) frill and spike-like epiparietal loci (p1) ornamentation with the stratigraphically lower Diabloceratops. Both parsimony and Bayesian phylogenetic analyses place Machairoceratops as an early-branching centrosaurine. However, the parsimony-based analysis provides little resolution for the position of the new taxon, placing it in an unresolved polytomy with Diabloceratops.
Objectives: To quantify personal time-weighted average respirable dust and quartz exposure on a s... more Objectives: To quantify personal time-weighted average respirable dust and quartz exposure on a sandy, a sandy loam, and a clay soil farm in the Free State and North West provinces of South Africa and to ascertain whether soil type is a determinant of exposure to respirable quartz.
USA: American Association of Petroleum …, Jan 1, 2009
The Wahweap Formation (Fm) is a ~400 m thick package of fluvial/estuarine channel sandstones and ... more The Wahweap Formation (Fm) is a ~400 m thick package of fluvial/estuarine channel sandstones and floodbasin mudstones deposited adjacent to the Western Interior Seaway (WIS) during the Late Cretaceous. It contains four informal members: the lower, middle, upper and capping sandstone members. This study aims to test existing tectono-eustatic basin models and reconstruct the sedimentary and tectonic history of the southern Cordilleran foreland basin during this important interval.
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