Bailiella tenuicincta ( Linnarsson, 1879 )

Unger, Tanja, Hildenbrand, Anne, Stinnesbeck, Wolfgang & Austermann, Gregor, 2022, Biostratigraphy and taxonomy of polymerid trilobites of the Manuels River Formation (Drumian, middle Cambrian), Newfoundland, Canada, Geodiversitas 44 (33), pp. 1051-1087 : 1064-1065

Bailiella tenuicincta ( Linnarsson, 1879)

( Fig. 9 )

Conocoryphe tenuicincta Linnarsson, 1879: 18 , 19, pl. 2, figs 23-25.

Bailiella tenuicincta – Westergård 1950: 26, 27, pl. 5, figs 6a-d, 7a, b, 8a, b, 9 (?). — Hutchinson 1962: 105, 106, pl. 15, figs. 3, 4a- d. — Rudolph 1990: 19, text-fig. 4; 1994: 192, 193, pl. 23, fig. 3 (?). — Weidner & Nielsen 2014: 74, fig. 43B.

Bailiella aff. B. tenuicincta – Martin & Dean 1988: 19, pl. 2, figs 7, 12.

Bailiella cf. tenuicincta – Chirivella Martorell et al. 2015: 177, figs 4A-I; p. 179, figs 5A, B.

LECTOTYPE. — Specimen no. SGU 4524 , Swedish Geological Survey (Sveriges Geologiska Undersökning), Uppsala, Sweden, originally figured in Linnarsson (1879) and designated as lectotype by Westergård (1950). From the Exsulans Limestone Bed, Tomagnostus gibbus Zone, Gislöv , on the shore 1 km south of Brantevik , Scania, Sweden.

DIAGNOSIS. — Anterior margin narrow; glabella with three pairs of shallow to faint furrows; occipital ring with node; dense fine granulose ornamentation with scattered small granules (based on Linnarsson 1879, with modifications).

MATERIAL EXAMINED. — Four cranidia of Bailiella tenuicincta ( NFM F-2972; NFM F-3168; NFM F-3169; NFM F-3200). All specimens range between 8.52 and 16.67 m ( Fig. 2 ) of the Manuels River Formation, type locality, Conception Bay South, Newfoundland, Canada .

OCCURRENCE. — Bailiella tenuicincta is a rare middle Cambrian taxon, documented from southeastern Canada, eastern Newfoundland, in the Paradoxides hicksi and Paradoxides davidis Zones ( Hutchinson 1962; Martin & Dean 1988). The taxon also occurs in Sweden ( Ptychagnostus (Triplagn.) gibbus Zone ; Westergård 1950, 1953), Bornholm in Denmark, ( Ptychagnostus (Triplagn.) gibbus Zone ; Westergård 1950; Agnostus atavus Zone ; Weidner & Nielsen, 2014) and Spain (upper Badulesia tenera to lower Badulesia granieri zones; Chirivella Martorell et al. 2015).

DESCRIPTION

The cranidia range from 7.0 mm to 34.0 mm in width and 4.4 mm to 18.0 mm in length, while the glabella varies from 2.5 to 10.0 mm in width and 2.8 to 10.5 mm in length. All specimens are well to very well-preserved internal casts. One specimen (NFM F-2972) has two to three pairs of faint glabellar furrows. Posterior pair is aligned towards the occipital ring.

REMARKS

The species is closely related to B. aequalis as discussed above. According to Weidner & Nielsen (2014) the stratigraphic range of B. tenuicincta is similar to that of Bailiella impressa ( Linnarsson, 1879) , from which it differs in having an evenly convex cranidium and shallow axial and border furrows. Westergård (1950) figured three cranidia and one pygidium. Granulation of the pygidium ( Westergård 1950: pl. 5, fig. 9) corresponds to that of the cranidia and is therefore assigned to the species, but this assignment is here considered questionable. A cranidium illustrated by Rudolph (1990: 19, text-fig. 4) may correspond to B. tenuicincta , but the resolution of the image is too low to evaluate the assignment and is therefore questionable.

Figures

FIG. 9. — Bailiella tenuicincta (Linnarsson, 1879): A, internal cast of a cranidium, scattered granules and occipital node preserved (NFM F-2972 from 8.52 m); B, internal cast of a cranidium, scattered granules and occipital node preserved, partly covered with sediment (NFM F-3200 from 8.52 m). Scale bars: 1 mm.

FIG. 2. — Lithology of the type locality of the Manuels River Formation, range chart of the here described species. Agnostid biozones from Hildenbrand et al. (2021) and polymerid biozones from Howell (1925).