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

PeerJ

article

Guang-Hui Xu¹ 

[1] Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences;CAS Center for Excellence in Life and Paleoenvironment

关键词: Fossils;    Holostei;    Halecomorphi;    Ionoscopiformes;    Evolution;   

DOI  :  10.7717/peerj.7184

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

The extinct ray-finned fish taxon Robustichthys luopingensis from 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, Robustichthys has so far not been described in detail and its phylogenetic position within the Holostei was controversy. This study provides a redescription and revision of Robustichthys based 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 of Robustichthys is presented. Results of a cladistic analysis confirmed Robustichthys as an ionoscopiform within the Halecomorphi; the previous placements of Robustichthys as a basal ginglymodian and Ionoscopidae as a basal amiiform clade are not supported. The sister group relationship between Sinamiinae (Sinamia and Ikechaoamia) and Amiinae (Amia and Cyclurus) within the Amiidae is newly recognized. This revised topology provides new insights into the evolution and historical paleoecology of halecomorph fishes.

【 授权许可】

CC BY