HETEROSTRACI LANKESTER, 1868 HETEROSTRACI INDET. GEN. ET SP. (TABLE 1; SUPPL. 1, FIGS. 7, 11, 12, 14, 18) Referred specimens —Scale fragments were collected from BC II section at six levels from 430.5’ to 513’ (131.2- 156.4 m): Roberts Mountains Formation. Remarks —Most remains are conjoined tesserae such as the three small irregular tesserae from level 458.67’ (Suppl. 1, fig. 11). Some (Suppl. 1, figs. 7, 14, 18) resemble traquairaspid remains with slender oak-leaf pattern tubercles: traquairaspids typically range from Přidolí to early Lochkovian. One plate from level 468’ (Suppl. 1, fig. 12) is pteraspid- or poraspid-like, typical of early Lochkovian elsewhere (e.g., Turner et al. 2017). Turner and Murphy (1988, fig. 1.1-6, 8-15, 24) described heterostracan microremains from the Lochkovian Simpson Park section, Nevada. Parkes (1995) also identified heterostracan remains in two levels of BC II (402’, 446’). As yet, there is no major review of heterostracan dermal scales; a handbook and major description of Cornwallis Island fauna are awaited (D.K. Elliott pers. comm. 2021, Thorsteinsson and Elliott 2022).

Published as part of 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., pp. 1-32 in PaleoBios 40 (4) on page 19, DOI: 10.5070/P940454153, http://zenodo.org/record/10913559