An articulated teleostome fish from the Late Silurian (Ludlow) of Victoria, Australia

WA Museum Records and Supplements | Updated 9 years ago

Abstract - The oldest articulated teleostome (?acanthodian) fish yet found in Australia, Yealepis douglasi gen. et sp. nov., is described from Yea in central Victoria. The specimen was associated with the Lower Baragwanathia Plant Assemblage in the Late Silurian (Ludlow) Yea Formation. The middle part of the body squamation is well preserved in part and counterpart, showing pectoral, pelvic and anal fins. The normal body scales are square-crowned, 0.8 to 1.5 mm wide, with a base wider than the crown. The crown bears short radial ridges along the anterior margin, and several vertical and / or radial ridges along the posterolateral sides. The only overlapping scales are the small, elongated scales near the distal margins of the fin webs. Dermal shoulder girdle plates, and fin and intermediate spines, are absent. The noncaudal fin webs do not bear the spines along the leading edges which are diagnostic for acanthodian fishes. This new genus is assigned to the Teleostomi, and provisionally to the Acanthodii, based on the type of scale and squamation pattern. Order and family are indeterminate, as it also lacks diagnostic characters for the recognized acanthodian orders. Alternatively, the new genus could represent a stem-group teleostome.