Neopterygian phylogeny: the merger assay

Area of Science:

• Paleontology
• Evolutionary Biology
• Ichthyology

Background:

• The phylogenetic placement of fossil actinopterygians is crucial for understanding early vertebrate evolution.
• The genus ^†Ticinolepis from the Middle Triassic represents a key taxon for investigating Neopterygian relationships.

Purpose of the Study:

• To elucidate the phylogenetic relationships of ^†Ticinolepis within the context of fossil actinopterygians.
• To reconstruct the evolutionary history and diversification patterns of crown-neopterygian clades.

Main Methods:

• Cladistic analysis using the largest morphological dataset for fossil actinopterygians to date.
• Integration of previously published and newly proposed characters for comprehensive phylogenetic reconstruction.

Main Results:

• ^†Ticinolepis is identified as the most basal Ginglymodi.
• Monophyly of Teleostei, Holostei, Halecomorphi, and Ginglymodi is supported, with some differences from previous studies.
• Confirms rapid radiation of Halecomorphi and Ginglymodi in the Early-Middle Triassic and Teleostei in the Late Triassic.

Conclusions:

• Phylogenetic hypothesis highlights rapid diversification events for major actinopterygian clades during the Mesozoic.
• Crown-group Halecomorphi, Ginglymodi, and Teleostei originated through parallel radiations in the Late Jurassic.