Ogygiocarella
Ogygiocarella Harrington and Leanza, 1957, is a genus of asaphid trilobites that lived during the Middle Ordovician Period.
Etymology
The generic name, Ogygiocarella, refers to "Ogygia", the seventh daughter of Amphion and Niobe, which name is combined with "-care-", from the Greek "akares", meaning short, and finally "-ella", the diminutive form.History
The first written record of a trilobite was by Edward Lhuyd in a letter written to Dr. Martin Lister and published in his Lithophylacii Britannici Ichnographia. The letter was accompanied by a page of etchings of fossils, one of which was found by him near Llandeilo, probably on the grounds of Lord Dynefor's Castle. One etching figured a fossil described as the "… Sceleton of some Flat-Fish …". and is sufficiently detailed to be now identified as the trilobite Ogygiocarella debuchii.Image:Flatfish Lhwyd.jpg|left|thumb|Etching of O. debuchii by Rev. Edward Lhwyd, made in 1698
Type species
Asaphus debuchii Brongniart.Whittard wrote: "Harrington and Leanza state that Asaphus debuchianus is the type species which was described and figured by Brongniart ; the specific name in this form was not used by Brongniart in the 1822 publication, but he used A. debuchii instead". The somewhat confused nomenclatorial history regarding the type species of Ogygiocarella was further discussed and clarified by Whittard.
Distribution
The genus Ogygiocarella presently appears to be confined to Wales and Shropshire, England, first occurring in the Lower Llandeilian Stage as developed at Llandeilo in Wales and disappearing in the lowest Caradoc Series graptolite zone of Nemagraptus gracilis in Shropshire.Only two almost identical species of Ogygiocarella are currently recognized, namely O. debuchii and O, angustissima and differentiation of the two relies on the presence and preservation of their pygidia.
O. debuchii is the most common trilobite species to occur within the Ordovician Shelve inlier, Shropshire, appearing in the middle part of the Meadowtown Formation and persisting into the overlying Rorrington Shale Formation where it is much less abundant. The species is characterised by eleven pairs of pygidial pleural ribs, although a twelfth vestigial pair is sometimes evident.
O. angustissima , on the other hand, is actually rare In Shropshire and confined to the upper part of the Meadowtown Formation. Within the Builth-Llandrinod inlier of mid-Wales, however, the species occurs slightly higher stratigraphically and is commonly associated with Nemagraptus gracilis within the lowest Caradoc Series. O. angustissima, differs from O. debuchii in having mainly thirteen instead of eleven ribs in the pygidium, and with a fourteenth pair faintly indicated in some specimens.
Ogygiocarella cf. angustissima is recorded from the Caerhys Shale Formation in the main part of Porth Gain Slate Quarry, Abereiddy Bay, Pembrokeshire, Southwest Wales.