01554nas a2200157 4500008004100000245011500041210006900156300001200225490000700237520103400244653002501278100001601303700001901319700001701338856004101355 2013 eng d00aFirst Middle Ordovician Ostracods from Western Avalonia: Paleogeographical and Paleoenvironmental Significance0 aFirst Middle Ordovician Ostracods from Western Avalonia Paleogeo a269-2760 v873 a

Two new species of ostracods, Conchoprimitia cassidula n. sp. and Sorornanopsis avalonensis n. gen. n. sp., represent the first described Middle Ordovician ostracods from western Avalonia. They were recovered as phosphatized carapaces dissolved out of a late early Darriwilian (ca. 467 Ma) limestone boulder from the Triassic Lepreau Formation of New Brunswick, Canada. The ostracods form a low-diversity component of a higher energy, near-shore, shelf marine fauna dominated by the trilobites Neseuretus and Stapleyella and by the conodonts Drepanoistodus and Baltoniodus. The low diversity of this Avalonian ostracod fauna contrasts with more diverse (tens of species), coeval ostracod faunas from Laurentia and Baltica. The association of Darriwilian ostracods and trilobites from New Brunswick demonstrates continuing exchange of open marine, cool water biota between Avalonia, Baltica, and West and North Gondwana that began in the late early Cambrian.

10ageology paleontology1 aLanding, E.1 aMohibullah, M.1 aWilliams, M. uhttp://dx.doi.org/10.1666/12-065R1.1