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.
Highlights
The Neopterygii are the main group of actinopterygian fishes, and include the Teleostei, which account for almost half of modern vertebrate biodiversity
According to the cladistic analysis performed by López-Arbarello, Stockar & Bürgin (2014), Archaeosemionotus is an halecomorph closely related to the early Middle Triassic (Anisian) Robustichthys luopingensis Xu, Zhao & Coates, 2014, from China and the Late Jurassic (Kimmeridgian) Ophiopsis muensteri Agassiz, 1833, from Germany
Parasemionotids and various fossil holosteans the facet is in an equivalent position, but it probably remained cartilaginous throughout life (e.g., ‘‘Pholidophorus’’ germanicus, Siemensichthys macrocephaluans, Pachycormus curtus, Heterolepidotus in Patterson, 1975)
Summary
The Neopterygii are the main group of actinopterygian fishes, and include the Teleostei, which account for almost half of modern vertebrate biodiversity. The origin of this important clade goes back to the Palaeozoic (Hurley et al, 2007; Sallan, 2014), but its most important radiation occurred in the early Mesozoic (Friedman, 2015). Ginglymodi, Halecomorphi and Teleostei are the three major clades currently recognized among crown neopterygians (Actinopterygii: Neopterygii). Ginglymodians and halecomorphs are extremely poorly represented today, How to cite this article López-Arbarello et al (2016), New holostean fishes (Actinopterygii: Neopterygii) from the Middle Triassic of the Monte San Giorgio (Canton Ticino, Switzerland).
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