New Triassic teleosts (Actinopterygii, Teleosteomorpha) from northern Italy and their phylogenetic relationships among the most basal teleosts

This study provides new evidence of the diversity of Middle–Late Triassic teleosts with the description of new pholidophorids from Italy. The results of the phylogenetic analysis confirm the sister-group relationship [†Aspidorhynchiformes + †Pachycormiformes] as members of Teleosteomorpha and †Prohalecites as the oldest teleosteomorph. The apomorphy-based Teleostei includes a new interpretation of †Pholidophoriformes as a monophyletic group supported by numerous synapomorphies and comprising two families, †Pholidophoridae and †Eurycormidae, fam. nov. The latter is only known from the Upper Jurassic of Europe. The monophyletic family †Pholidophoridae is known by about a dozen European taxa and a Middle Triassic genus (†Malingichthys) from southern Asia, which is the oldest member of the family. The addition of new pholidophorids provides a new interpretation of the possible relationships and taxonomic arrangements within the family †Pholidophoridae. The genera †Pholidorhynchodon and †Eopholidophorus stand as pholidophorids with a unique morphology of the upper oral margin, including a median rostral bone bearing a few large conical teeth, laterodermethmoids armed with large teeth, and the premaxillae displaced from the middle region of the oral margin. This study confirms previous hypotheses of character evolution among basal members of Teleostei, with implications for holostean character evolution. The synapomorphies shared by crown-group Teleostei appeared stepwise more than 140 million years ago over many speciation events and did not arise in a single ancestral species. The analyses of character distribution reflect the gradual accumulation of features that diagnose the crown group.
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Citation for this article: Arratia, G. 2017. New Triassic teleosts (Actinopterygii, Teleosteomorpha) from northern Italy and their phylogenetic relationships among the most basal teleosts. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1312690.