Diversidad de peces holósteos en niveles de la Formación Cerro Lisandro (Cenomaniano -Turoniano, Cretácico Superior) aflorantes en la localidad de Cerro Bayo Mesa, Provincia de Neuquén.

Abstract

Holostean are a group of actinopterygian fishes, whose fossil record extends from the Late Permian/Early Triassic up to the present. The classification and phylogenetic relationships of this group are still under debate, but it is composed of the divisions Ginglymodi, Halecomorphi and the Order Dapediiformes. The clade Holostei presents an interesting evolutionary history during the Mesozoic, with eight species currently recorded. In Argentina, this group of fishes is recorded in various sedimentary basins mainly in the Jurassic - Cretaceous, with a scarce fossil record that consists mainly of scales, vertebrae and teeth. The goal of this Final Degree Work is to describe and analyze isolated remains of holostean fishes from the Cerro Bayo Mesa locality (Cerro Lisandro Fm., middle-upper Turonian) in the province of Neuquén, Argentina. These remains consist of cranial fragments, vertebral centra, and scales, most of which are unpublished and preliminarily assigned to the family Lepisosteidae. The cranial fragments and vertebral centra were described anatomically and compared through the bibliography, whereas the scales were described morphologically and thin sections were made to study their microstructure. Thus, a premaxilla is assigned to the Amiidae family, a dentary fragment, a possible dentary fragment and a cranial bone, tentatively assigned as cf. Amiidae. Therefore, the vertebral centra were assigned to the Vidalamiinae subfamily. Finally, the assignment to Lepisosteidae of the scales and a vertebral centra is confirmed. At the same time, the possible systematic affinities of these materials are discussed, the diversity present from the associated materials, and the possible occurrence of the genus Melvius, based on a vertebral centra and the implications of the presence of this genus. Finally, the importance of the records studied here is highlighted, which represent new occurrences, expanding the knowledge of this group of fishes in Argentina.