The only known cyclopygid–‘atheloptic’ trilobite fauna from North America: the upper Ordovician fauna of the Pyle Mountain Argillite and its palaeoenvironmental significance

The trilobite fauna of the upper Ordovician (middle Katian) Pyle Mountain Argillite comprises a mixture of abundant mesopelagic cyclopygids and other pelagic taxa and a benthic fauna dominated by trilobites lacking eyes. Such faunas were widespread in deep water environments around Gondwana and terranes derived from that continent throughout Ordovician time but this is the only known record of such a fauna from North America and thus from Laurentia. It probably reflects a major sea level rise (the ‘Linearis drowning events’) as does the development of coeval cyclopygid-dominated deep water trilobite faunas in terranes that were marginal to Laurentia and are now preserved in Ireland and Scotland. The Pyle Mountain Argillite trilobite fauna occurs with a deep water Foliomena brachiopod fauna and comprises 22 species. Pelagic trilobites (mostly cyclopygids) constitute 36% of the preserved sclerites, and 45% of the fauna is the remains of trilobites lacking eyes, including one new species, Dindymene whittingtoni sp. nov. Three species of cyclopygid are present, belonging in Cyclopyge, Symphysops and Microparia (Heterocyclopyge). Cyclopygids are widely thought to have been stratified in the water column in life and thus their taxonomic diversity reflects the relative depths of the sea-beds on which their remains accumulated. A tabulation of middle and upper Katian cyclopygid-bearing faunas from several palaeoplates and terranes arranged on the basis of increasing numbers of cyclopygid genera allows an assessment of the relative depth ranges of the associated benthic taxa. The Pyle Mountain Argillite fauna lies towards the deeper end of this depth spectrum

The burden and measurement of cardiovascular disease in SSc

The prognosis for patients with systemic sclerosis (SSc) has improved in the past three decades, with fewer patients succumbing to renal-crisis-related death. While pulmonary fibrosis and hypertension are currently the most frequent causes of death, there is evidence that cardiovascular disease will have an important role in the long-term prognosis of SSc in the future. Ischemia-reperfusion injury and endothelial dysfunction are cardinal features of SSc, and may predispose a patient to microvascular disease and atherosclerosis. In order to alleviate the cardiovascular burden in patients with SSc, it is important to detect endothelial dysfunction, microvascular flow disturbance and atherosclerosis. Noninvasive techniques that evaluate flow-mediated dilatation and arterial pulse waves (endothelial function measurements), microvascular blood flow (measurement of the microcirculation), carotid intima-media thickness and left ventricular hypertrophy (detection of atherosclerosis) are recommended. In addition, these measurements will facilitate trials of therapeutic strategies that, in addition to controlling conventional risk factors, prevent and treat cardiovascular disease in patients with SSc. © 2010 Macmillan Publishers Limited. All rights reserved.link_to_subscribed_fulltex

The Reimer-Tiemann reaction

No abstract