Osteology and phylogeny ofRobustichthys luopingensis, the largest holostean fish in the Middle Triassic

Autor: Guang-Hui Xu
Rok vydání: 2019
Předmět:
Zdroj: PeerJ
PeerJ, Vol 7, p e7184 (2019)
ISSN: 2167-8359
Popis: The extinct ray-finned fish taxonRobustichthys luopingensisfrom Luoping, eastern Yunnan, China represents the largest holostean known in the Middle Triassic. Despite its potential significance for investigating the holostean phylogeny and reconstructing the Triassic marine ecosystems,Robustichthyshas so far not been described in detail and its phylogenetic position within the Holostei was controversy. This study provides a redescription and revision ofRobustichthysbased upon a comparative study of eight type specimens and nine new specimens. Newly recognized information includes a toothed parasphenoid, a pair of premaxillae not pierced by the olfactory nerve, a splint-like quadratojugal, a hatchet-shaped hyomandibula, an hourglass-shaped symplectic, anterior and posterior ceratohyals, a complete series of branchiostegal rays, and sclerotic bones. A revised reconstruction ofRobustichthysis presented. Results of a cladistic analysis confirmedRobustichthysas an ionoscopiform within the Halecomorphi; the previous placements ofRobustichthysas a basal ginglymodian and Ionoscopidae as a basal amiiform clade are not supported. The sister group relationship between Sinamiinae (SinamiaandIkechaoamia) and Amiinae (AmiaandCyclurus) within the Amiidae is newly recognized. This revised topology provides new insights into the evolution and historical paleoecology of halecomorph fishes.
Databáze: OpenAIRE