Trilobites of the Pabos Formation (Ashgillian, Upper Ordovician), Percé area, Quebec

Abstract

The Ashgillian Pabos Formation underlies the Ashgillian-Llandoverian White Head Formation and consists, in the immediate Percé area, of 21 trilobite taxa. Of these, 11 are left in open nomenclature, four of which are summarily described, commented upon, and illustrated. Ten species are specifically determined and three of these are new: Remopleurides arenosus, Achatella (Achatella) clivosa, and Meadowtownella sacerdos. Hibbertia whittingtoni (McNamara, 1979) is a junior secondary homonym and renamed H. conistonensis. The Ashgillian-Llandoverian cheirurines of the Percé area are reviewed and new generic assignments suggested; these are a major component of the Pabos trilobite fauna. Revision of Ceraurinus icarus, a widely distributed North American species, shows its inherent variability; limits of variation, more complete descriptions, and stratigraphic distribution of most previously described species are also given. The distinctive trinucleid Novaspis elevata occurs in the Pabos, outside the immediate Perce area. Almost all of the Pabos trilobites are also present in the coeval Grande Coupe beds of the Matapedia Group; otherwise they are a mixture of taxa with greatest faunal affinities with North American or northwestern European taxa of the same age.

A systematic revision of the family Harpetidae (Trilobita)

“…It should also be noted that recent reviews by Owen and Clarkson (1992) and Lesperance and Weissenberger (1998) place Platyharpes Whittington, 1950b andParaharpes Whittington, 1950b in synonymy with Hibbertia Jones and Woodward, 1898.…”

“…Metaharpes amibouei Lamont, 1948b;Harpes anticostiensis Twenhofel, 1928;H. balclatchiensis Whittington, 1950a; Hibbertia conistonensis Lesperance andWeissenberger, 1998 [= Paraharpes whittingtoni McNamara, 1979]; Harpes costatus Angelin, 1854; H. dalecarlicus Thorslund, 1930; (Eoharpes) hornei Reed, 1914;Paraharpes inghami Remarks Whittington (1950a: 11) noted the close relationship between Paraharpes and Platyharpes, but did not refer to any strong similarities between Hibbertia and Paraharpes. There were no further mentions of any similarities between Hibbertia and Paraharpes in Whittington's (1950b) discussion of the synonymy of Platyharpes and Paraharpes.…”

Late Ordovician trilobites from the Taimyr Peninsula, Arctic Russia

“…Jaanusson & Ramsk€ old (1993) erected Vironiaspis as a new subgenus of Achatella, distinguished from Achatella (Achatella) in the cranidial characters by the lack of abaxial shallowing of S2 and large eyes where the anterior end reaches the axial furrow, but the subgenus was not supported by Swisher et al (2016). All species of Achatella are morphologically very similar, raising the question of synonymy for many of these (Owen 1986;Lesp erance & Weissenberger 1998;Swisher et al 2016). Holloway (2004) commented that Achatella is morphologically close to Monorakos Schmidt, 1886.…”

The first Hirnantian (uppermost Ordovician) odontopleurid trilobite from Western Gondwana (Argentina)

“…Among these, Kettneraspis Prantl & Přibyl, 1949 has only been tentatively reported from Ordovician strata (e.g. Lespérance & Weissenberger, 1998), it includes species only reliably known from the Silurian and Devonian. In addition, an emended diagnosis provided by Curtis & Lane (1998), indicates a wide (tr.)…”