Bailiaspis
Bailiaspis is a Middle Cambrian trilobite genus belonging to the family Conocoryphidae. Within the Acado-Baltic region, the genus ranges from Wuliuan into Guzhangian age strata.
Diagnosis
A genus of Conocoryphidae in which backward expansion of the anterior cranidial border and the border furrow arched sharply towards posterior combine to form a distinct medial 'plectrum'.
Species
Type species: Conocephalites elegans Hartt in Dawson, 1868, by original designation. From the Middle Cambrian, Chamberlain's Brook Formation, Eccaparadoxides eteminicus Zone, of Saint John, New Brunswick.
other speciesB. dalmani .B. glabrata .B. nicholasi Resser, 1936, p. 14 .B. venusta Resser, 1937 .B. inflata Lake, 1940 B. tuberculata Lake, 1940B. cf. tuberculata Lake, 1940 and B. aff. tuberculata Lake, 1940B. latigenae Hutchinson, 1962B. griffei B. menneri Korobov, 1973B. bobrovi Korobov, 1973B. jakutensis Korobov, 1973B. botomensis Korobov, 1973B. picta Korobov, 1973B. curta Korobov, 1973B. senonta Korobov, 1973
Distribution
B. dalmani occurs in Southern Sweden in the Exsulans Limestone and immediately adjacent shale layers at various locations and Ptychagnostus gibbus Biozone at Porth-y-rhaw, St David's, South West Wales. The Whitesands Bay Formation is conventionally referred to the biozone of Paradoxides aurora, following Hicks. However, that species is a probable subjective junior synonym of Mawddachites hicksii, and so no independent aurora biozone can be recognized.B. glabrata was originally derived from the Zone of Solenopleura brachymetopa of Andrarum, Scania and at the same horizon on the Danish island of Bornholm. The species also occurs in the Manuels River Formation, davidis Zone of Deep Cove, Cape St Mary's Peninsula, Newfoundland, in the Valtorres Formation at Purujosa, Iberian Chains, NE Spain, and in the lower part of the Jbel Lmgaysmat Formation in the central Anti-Atlas of Morocco. Westergård noted that "An incomplete and somewhat distorted cranidium identified as Conocoryphe cf. dalmani by Nicholas and later described and illustrated by Lake under the name of Bailiaspis nicholasi Resser MS., seems to agree with glabrata", an opinion upheld by Young et al.. The specimen was obtained from Nicholas's 'thin calcareous grit' that spans the junction of the Nant-y-big and Maentwrog Formations near Nant-y-big, Porth Ceiriad, North West Wales and the fauna indicates correlation with the Andrarum Limestone of Andrarum, Scania, Sweden. Poorly preserved specimens assigned to Bailiaspis cf. glabrata have also been reported from the upper Languedocian strata of the Coulouma-Refescals sector of the southern Montagne Noire.B. venusta Resser, 1937 . Collected from the Fossil Brook Member of the Chamberlain's Brook Formation, P. bennettii zone on Manuels River B. inflata Lake, 1940. Comley Breccia Bed, = upper gibbus – fissus Biozones Comley, Shropshire, England. Also recorded by Fletcher from the Chamberlain's Brook Formation, Agraulos affinis Zone in Wester Cove of Branch, St. Mary's Bay, Newfoundland. Fletcher stated, however, that "the species close to Bailiaspis inflata in this A. affinis faunal assemblage may indicate a slightly earlier occurrence than the type specimen" from Comley.B. tuberculata Lake, 1940. Recorded from Illing's level A4 in the Abbey Shale Formation of Nuneaton, Warwickshire, central England. Illing assigned his level A4 to the former Paradoxides aurora Zone which has been correlated with some reserve to the Ptychagnostus gibbus Biozone. B. cf. tuberculata, B. aff. tuberculata and B. sp. occur in the Mansilla Formation of the Iberian Chains, NE Spain and indicate a range from the Eccaparadoxides asturianus Zone to the lowermost Badulesia tenera Zone, which correspond to the late Wuliuan and, probably, the lowermost Drumian Stages.B. latigenae Hutchinson, 1962 was collected from a loose limestone nodule at only one beach locality in Deep Cove, St. Mary's Bay. The north and west shores of Deep Cove expose a section through Elliott Cove, Manuels River, and Chamberlain's Brook Formations and judging from the faunal association the nodule must have come from the hicksii, or the lowest part of the davidis zone within the Manuels River Formation.B. griffei is from the Middle Cambrian La Gardie Formation, Point 13, Ferrals-les-Montagnes, Hérault, Languedoc-Roussillon, FranceB. menneri Korobov, 1973 is from the Middle Cambrian Olenek Formation of the Siberian Platform, Russia.B. bobrovi Korobov, 1973B. jakutensis Korobov, 1973B. botomensis Korobov, 1973B. picta Korobov, 1973B. curta Korobov, 1973B. senonta Korobov, 1973