New holostean fishes (Actinopterygii: Neopterygii) from the Middle Triassic of the Monte San Giorgio (Canton Ticino, Switzerland)

PeerJ. 2016 Jul 19:4:e2234. doi: 10.7717/peerj.2234. eCollection 2016.

Abstract

The new neopterygian genus Ticinolepis, including two new species T. longaeva and T. crassidens is described from Middle Triassic carbonate platform deposits of the Monte San Giorgio. The anatomy of this fish shows a mosaic of halecomorph and ginglymodian characters and, thus, the new taxon probably represents a basal holostean. During the latest Anisian to earliest Ladinian the two new species coexisted in the intraplatform basin represented by the uppermost Besano Formation, but only T. longaeva sp. nov. inhabited the more restricted basin represented by the Ladinian Meride Limestone (except for the Kalkschieferzone). The more widely distributed type species shows interesting patterns of intraspecific variation including ontogenetic changes and morphological variation over time. The second species presents anatomical features that strongly indicate a strictly durophagous diet. The different distribution of the species is interpreted as a result of habitat partitioning and different adaptability to palaeoenvironmental changes.

Keywords: Durophagy; Ginglymodi; Habitat partitioning; Halecomorphi; Holostei; Intraspecific variation; Middle Triassic; Trophic specialization.

Grants and funding

The work of ALA was financed by the German Research Foundation (DFG LO 1405/3-1 to 3-3), the Canton Ticino through the Museo Cantonale di Storia Naturale (Lugano) and Max Kuhn (Uster). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.