By Richard A. Fortey, David L. Bruton
This monograph describes early Ordovician (Ibexian:Tremadocian–early Floian) trilobites from Northern Spitsbergen from the part during the Kirtonryggen Formation adjoining to Hinlopen Strait. The Formation is split into 3 contributors, every one with targeted trilobites jointly representing the fullest identified succession from the Bathyurid biofacies of the jap Laurentian carbonate platform. prior examine at the Ordovician of Spitsbergen is summarised and correlations with comparable faunas formerly defined from Canada, Greenland, western Newfoundland, Vermont–New York country, Oklahoma and Missouri are discussed. Taxonomic difficulties are mentioned intimately resulting in the popularity of fifty three species, of which 15 are new, belonging to 31 genera together with 4 new. Twenty-four taxa are defined less than open or tentative nomenclature. The reduce Member yields the earliest identified occurrences of the Illaenoidea, Proetoidea and Scutelluoidea, assisting the hypotheses touching on the foundation of latest significant clades to inshore habitats.
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Additional info for Fossils and Strata: Lower Ordovician trilobites of the Kirtonryggen Formation, Spitsbergen
Nov. Fortey, pp. 81–84, pl. 27, ﬁgs 1–12. 1989 Catochia ornata Fortey, 1979; Boyce, p. 49, pl. 26, ﬁgs 5, 6. Material. 74. Stratigraphic range. – Nordporten Member, 150– 190 m Petigurus nero fauna. Discussion. – The free cheek of C. ornata is unique in having a distinctive, single line of ornament obliquely following the base of the eye. In this character, it obviously differs from the tuberculate cheek of C. hinlopensis described above. We have only been able to ﬁnd free cheeks of this species in the upper part of the Nordporten Member, which are ﬁgured here for comparison with the full description of Fortey (1979) and the illustration of a similar cheek from Cape Norman, western Newfoundland by Boyce (1989).
Material. 090. Stratigraphic range. – 105–190 m from base of Nordporten Member, upper Petigurus groenlandicus fauna to P. nero fauna. Diagnosis. ) except at frontal glabellar lobe. Short pre-glabellar ﬁeld; adaxial part of posterior ﬁxed cheek inﬂated. Pygidium with three or four Lower Ordovician trilobites from Spitsbergen 33 pairs of narrow pleural furrows and interpleural furrows hardly deﬁned. Discussion. – This species was named by Cullison, 1944, as Bolbocephalus st. clairi, a name that unfortunately already existed as a nomen nudum coined by E.
This is by analogy with other bathyurid cheeks. The lateral border is convex with a steep outer slope. Posterior border less convex and posterior border furrow distinct, but wider than the lateral border furrow at its narrowest. Genal ﬁeld is convex, somewhat bulging. The area between the abaxial end of the posterior border furrow and the margin is swollen into a triangular, tumid region, which, on its dorsal surface, carries a series of six to eight remarkably wide, raised ridges running back sub-parallel to the lateral genal margin.
Fossils and Strata: Lower Ordovician trilobites of the Kirtonryggen Formation, Spitsbergen by Richard A. Fortey, David L. Bruton