AN EARLY SILURIAN MYODOCOPE OSTRACOD FROM GREENLAND: PRE-ADAPTATIONS FOR LIFE IN THE WATER COLUMN

A new species of the Herefordshire Lagerstätte myodocope ostracod genus Pauline occurs in the Lower Silurian (late Telychian) of North Greenland, from a limestone boulder within the Pentamerus Bjerge Formation south of Kap Schuchert, Washington Land. It is reasonable to transpose the soft anatomy of 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 of the UK. 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. However the anatomical adaptations that enabled this transition (i.e. swimming antennae, gills, lateral eyes) were already present in early Silurian Myodocopes such as Pauline.