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Systematic collecting through the upper Wenlock (upper Homerian) and lower Ludlow (Gorstian and lowermost Ludfordian) Silurian rock succession of the Long Mountain, Powys, Wales, identifies some 48 chitinozoan species that distinguish four biozones, two subzones and an interregnum. Consideration of the chitinozoan biozones together with those of the graptolites enables a local three-fold subdivision of the late Homerian lundgreni graptolite Biozone, and the distinction of lower and upper intervals for the Gorstian incipiens graptolite Biozone. The base of the Ludlow Series in the Long Mountain more or less equates to the base of the Cingulochitina acme chitinozoan Biozone, although no key chitinozoan first or last appearance datums are associated with the series boundary itself. The new graptolite–chitinozoan biozonation allows enhanced correlation between upper Wenlock and lower Ludlow sedimentary deposits of the Lower Palaeozoic Welsh depositional basin and those of the palaeo-shelf in the stratotype Wenlock and Ludlow areas of Shropshire. Chitinozoans seem affected by the phenomena that caused the late Wenlock ‘Mulde extinction’ in graptolites but, with the final disappearance of 9 species and re-appearance of 11 species following an interval of overall low diversity, they seem to have suffered less severely than their macro-zooplanktonic contemporaries. [ABSTRACT FROM AUTHOR]

Here we record the occurrence of a new species of the Herefordshire Lagerstätte ostracod genus Pauline from the Lower Silurian (upper Telychian) of North Greenland. Pauline nivisis sp. nov. was recovered from a limestone boulder (Pentamerus Bjerge Formation) collected south of Kap Schuchert, Washington Land. It is reasonable to transpose the palaeobiology known from the Herefordshire Pauline avibella – body, limbs including swimming antennae, lateral eyes, gills and alimentary system – into the carapace of the Greenland species, which represents the oldest cylindroleberidid myodocopid and almost the oldest known myodocope, and is the first record of a Herefordshire Lagerstätte genus from outside the Welsh Borderland locality. Morphological, sedimentological and faunal evidence suggest that the Greenland species was nektobenthic. This is compatible with the notion that ostracods (specifically myodocopids) did not invade the water column until later in the Silurian, in the Wenlock and Ludlow epochs. Pauline is an Early Silurian link between ‘Baltic-British’ and North Laurentian ostracod faunas, endorsing the idea that the UK and Greenland were in close geographical proximity, near a remnant Iapetus Ocean, during late Llandovery time. [ABSTRACT FROM PUBLISHER]