Asterolepis cf. radiata Eichwald, 1840 sensu Agassiz 1844

• Main Authors: Downs, Jason P., Daeschler, Edward B., Lo, Nathanael, Carey, Emily N., Shubin, Neil H.
• Format: Other/Unknown Material
• Language: unknown
• Published: 2019
• Subjects: Biodiversity; Taxonomy; Animalia; Arthropoda; Insecta; Lepidoptera; Tortricidae; Asterolepis; Asterolepis cf. radiata; Nunavut; Ellesmere Island; Canada; Bird Fiord
• Online Access: https://zenodo.org/record/3703485; https://doi.org/10.5281/zenodo.3703485

Asterolepis cf. radiata Rohon, 1899 Asterolepis cf. radiata Rohon, 1899: 8. Asterolepis sp. – Daeschler et al. 2006: 759. — Downs et al. 2011a: 994. “Asterolepid placoderm” – Downs et al. 2013: 48. “Asterolepid antiarch” – Downs et al. 2018: 1. LOCALITY AND HORIZON. — NV2K17 locality (77˚09’59.1”N, 86˚16’9.42”W), Fram Formation near the eastern arm of Bird Fiord on southern Ellesmere Island, Nunavut Territory, Canada. Palynological data indicate an early Frasnian age (medius and maclarenii zones of Chi & Hills 1976). DIAGNOSIS. — Antiarch referred to Asterolepis by the presence of an anterior median dorsal plate that broadly overlaps the mixilateral plates (Moloshnikov 2008). Referred to Asterolepis cf. radiata by the presence of an external skeletal ornament that is composed entirely of rows of tubercles and/or ridges that radiate from the center of ossification to the margins of the plate (Rohon 1899). REFERRED MATERIAL. — NUFV 795, 797-800, 804, anterior median dorsal plate; NUFV 809, 825, posterior median dorsal plate; NUFV 846, 863, mixilateral plate; NUFV 883, partial anterior dorsolateral and mixilateral plates. DESCRIPTION OF THORACIC AND PECTORAL SKELETONS Anterior median dorsal plate (Fig. 6A, B) The five complete anterior median dorsal plates of Asterolepis cf. radiata (NUFV 795, 797-800) exhibit a size and shape range consistent with known material of A. radiata. Among these five specimens, the midline length of the plate is between 79.75 mm (NUFV 798) and 94.94 mm (NUFV 800) and width across the lateral corners (Fig. 6A [lc]) is between 54.41 mm (NUFV 798) and 68.09 mm (NUFV 800). The width/length index of the plate (width across the lateral corners × 100 / midline length), then, is between 65 and 73 for the five specimens. The lateral corners of these plates are positioned close to the midpoint of the plate’s length. This presents a differently shaped anterior median dorsal plate than that of those Asterolepis species with anterior median dorsal plate lateral corners near the plate’s caudal end ...