Scale morphology and specialized dorsal scales of a new teleosteomorph fish from the Aptian of West Gondwana

Abstract

Abstract. Scales of a new species of Teleosteomorpha from the continental Aptian of the south of South America are studied. These neopterygians are from the La Cantera Formation in central Argentina, and were previously identified as Pholidophoriformes. They present ganoid scales; most of them are rhombic with well-developed peg-and-socket articulations and possessing a smooth surface. They have a straight posterior margin, but occasionally, some scales of the flank have a sinuous posterior margin with one or two serrations. The shape of the scales varies along the body from large, rectangular and deeper than long scales behind the head to the preanal region to smaller and rhomboidal scales in the caudal region. There are a few horizontal rows along the flank and about 32 lateral line scales. Thick, round ganoid scales are present in the prepelvic region close to the ventral margin. The round and rhombic scales present growth lines, which form concentric ridges on the external side. A characteristic row of deep scales forms the dorsal margin on each side of the body; a row of median ridge scales is not present. This is a unique feature of the studied fishes. Scutes covered with unornamented ganoine precede the pelvic, dorsal, and anal fins, as well as the dorsal and ventral margins of the caudal fin. The posterior margin of the dorsal lobe of the caudal fin is formed by a single line of scales, which continues and covers the base of the first principal caudal ray. Histological studies reveal a lepisosteoid-scale type with multiple ganoine layers, lack of dentine, and the presence of canaliculi of Williamson. The macro-and micromorphology of the scales shows features that are found in other teleosteomorphs, but also in other neopterygians.

Digital light microscopy to characterize the scales of two goatfishes (Perciformes; Mullidae)

“…In ichthyological studies, general morphology of scales and their microstructures are used to categorize fishes and accordingly provide additional data to discriminate different groups of extinct (e.g., Giordano, Arratia, & Schultze, 2016) and extant fishes (Ferrito, Pappalardo, Fruciano, & Tigano, 2009; Gholami et al, 2013; Jawad, 2005; Khosravi, Shaker Golmakan, & Teimori, 2017; Teimori, 2016; Teimori, Motamedi, & Golmakan, 2017; Teimori, Motamedi, & Manizadeh, 2017). Most of these studies aimed to provide a wide range of valuable scale characters that can reflect a clear taxonomic status.…”

Macro- And Micromorphology of Scales from an Endemic South American Actinopterygian Family (Pseudobeaconiidae, Triassic, Cuyana Basin)

“…7.1-7.2, 7.4). Among Actinopterygii, preanal scutes are common features in holosteans (Giordano, et al, 2016) and also in basal clades such as, Perleidiformes (Yuan et al, 2022: fig. 8), Peltopleuriformes (Xu et al, 2018;Shen & Arratia, 2022) and Redfieldiformes (Gouiric-Cavalli, et al, 2017).…”

Diversity of vertebrate remains from the Lower Gogolin Beds (Anisian) of southern Poland

“…Morphotype 2 is smooth with growth structures (similar to growth rings of cycloid scales) visible on the external surfaces (Fig. 4B) resembling post-anal scales of teleosteomorphs (Giordano et al, 2016). The presented types might belong to different taxa (Märss, 2006;Antczak and Bodzioch, 2018), but they can also belong to one species, depending on the variability of its structure at different parts of the fish body (Patterson et al, 2002).…”