A new hump-backed ginglymodian fish (Neopterygii, Semionotiformes) from the Upper Triassic Chinle Formation of southeastern Utah

ABSTRACT

A new species of hump-backed semionotiform fish, Lophionotus sanjuanensis, gen et sp. nov., is described based on specimens recently and previously collected from the Upper Triassic Church Rock Member of the Chinle Formation of southeastern Utah. It is characterized by a deep body with a large postcranial hump, and dense tuberculation on the posterodorsal margin of the skull that continues into the dorsal ridge and dorsolateral flank scales. The vertical preoperculum bears a short and broad paddle-like ventral process. The infraorbital series expands ventral to the suborbital and contacts the anterior ramus of the preoperculum, although this character has also been observed in other deep-bodied semionotiform taxa. This taxon represents the first newly described semionotiform fish species from the western United States in over 45 years, and adds to knowledge of Triassic fishes biodiversity.

ACKNOWLEDGMENTS

I thank A. R. C. Milner (SGDS), J. I. Kirkland (Utah Geological Survey), J. Maisey (AMNH), and M. Getty (Natural History Museum of Utah) for the use of specimens in this study. H.-P. Schultze and G. Arratia aided in identification of characters. I thank H.-P. Schultze and M. P. Davis for constructive suggestions for improvement of the manuscript. I also thank the editors who have handled this manuscript, and A. López-Arbarello and J. Lane who provided insightful comments and suggestions. I additionally thank the following institutions: AMNH, Bureau of Land Management, Utah Department of Natural Resources, UMNH, NMMNHS, SGDS, University of Kansas (KU) Biodiversity Institute, and the Utah Geological Survey. I thank the Utah Friends of Paleontology for help in collecting and preparing specimens. This research was funded in part by the University of Kansas Biodiversity Institute Panorama Grant and KU Endowment Fund. Specimens collected in 2004 and 2005 for this study were collected under Utah State Institutional Trust Lands Administration permits 02-334 and 05-347.

Handling editor: Matt Friedman