Ptyctolepis brachynotus gen. et sp. nov. IVPP V23386: CT scan data and surface files of a new sarcopterygian from Early Devonian of South China

X-ray computed microtomography scanning for these specimens was performed at IVPP, Chinese Academy of Sciences (CAS), Beijing, China, using a 225 kV microCT. After scanning, data were segmented in Mimics (biomedical.materialise.com/mimics; Materialise, Leuven, Belgium). Surface meshes were then exported into and imaged in Blender (blender.org; Stitching Blender Foundation, Amsterdam, the Netherlands).High-resolution micro computed tomography (μCT) of three-dimensionally preserved skulls illuminates internal cranial anatomy of lobe-finned fishes, and provides evidence for the stepwise evolution of key sarcopterygian features, but also lend additional weight to the idea of a sudden and explosive episode of sarcopterygian evolution in the late Silurian and Early Devonian of China. Article abstract: Recent discoveries of psarolepids, putative stem sarcopterygians from the late Silurian and Early Devonian of South China, have increased our knowledge of the morphology and initial diversification of osteichthyans while highlighting incongruities in character evolution in the largest group of jawed vertebrates. Character-rich endocrania are incompletely preserved for these taxa, limiting a detailed understanding of complex internal morphology and evolutionary changes in the head skeleton. We report a new sarcopterygian (Ptyctolepis brachynotus gen. et sp. nov.) from the Pragian (Early Devonian) of South China, which preserves the only example of a completely ossified otoccipital division of the braincase in a stem sarcopterygian. The skull roof bears vermiculate ridged ornamentation, with middle and posterior pit-lines lying close to the midline. The paired hyomandibular facets sit dorsal to the jugular canal, representing a hitherto unobserved combination of derived and primitive character states. The suite of characters in this new taxon prompts a reassessment of early osteichthyan evolution, including the phylogenetic placement of psarolepids, which we suggest might branch from the osteichthyan—rather than sarcopterygian—stem.