Boreania undetermined

Burrow, Carole Jan, Murphy, Michael & Turner, Susan, 2023, Late Silurian to earliest Devonian vertebrate biostratigraphy of the Birch Creek II section, Roberts Mountains, Nevada, U. S. A., PaleoBios 40 (4), pp. 1-32 : 22-23

BOREANIA SP. CF. B. MINIMA

( TABLE 1 ; SUPPL. 1, FIGS. 10?, 11, 12, 22?, 25?)

Referred specimens — Rare ; 5 specimens in BCII: possibly one scale at level 457’ (139.3 m) ; one at level 458.67’ (139.8 m); one at level 468’ (142.6 m); possibly one scale at level 556.5’ (169.6 m); possibly one scale at level 591.5’ (180.3 m): Roberts Mountains Formation .

Description —Small rounded, presumed head or oral scales where the crown is only slightly larger than the base. The crown has numerous ridges and the rim is wavy. One head or special (lateral line?)scale from level 458.67’ has a high rounded crown with a distinct embayment at one place in the crown/neck interface and below on the deep base there is a large foramen, which might be related to a pore canal (Suppl. 1, fig. 11).

Remarks —The scales in Nevada most probably belong to B. minima but their rarity does not allow a definite assessment. One tripartite scale in 430.5’ could be B. minima or might be Trimerolepis tricava (see remarks above). Because of its earlier location in the section, an alternative identification for the scale at level 457’ might be Thelodus admirabilis Märss, 1982 but based on one poor scale, this is uncertain; these taxa are known from early to late Přidolí, respectively ( Märss et al. 2007). Karatajūtė-Talimaa (1985) defined the genus Boreania based on Turner’s (1984) assessment of a separate species that she called ‘ Turinia’ minima and similarities to southern Baltic specimens that Karatajūtė-Talimaa (1964) had referred to Turinia pagei . This taxon is typical of the latest Přidolí to lower Lochkovian of the Baltic states, the Welsh Borders, Spitsbergen and October Revolution Island ( Märss et al. 2007). Usually, B. minima is associated with the key Lochkovian taxon Turinia pagei . Interestingly, the latter taxon is noticeable by its absence, except for one or two possible broken turiniid-like scales (see above).