A new lizardfish (Teleostei, Aulopiformes) from the Late Cretaceous Bearpaw Formation of Alberta, Canada, with a revised diagnosis of Apateodus (Aulopiformes, Ichthyotringoidei)

ABSTRACT

A new aulopiform, Ursichthys longiparietalis, gen. et sp. nov., preserved within and around the body cavity of a mosasaur, Mosasaurus missouriensis, is described from the Bearpaw Formation (upper Campanian, ca. 74.8 Ma) of Alberta, Canada (paleolatitude = 57°N). The partial skeleton consists of a partial skull associated with other isolated bones, including parasphenoid, hyomandibula, cleithrum, caudal peduncle centrum, scale, and many disarticulated fin rays. Many of those elements show evidence of bite damage considered to have been inflicted by the mosasaur. This taxon can be differentiated from other aulopiforms in having a dorsoventrally compressed neurocranium; short frontals; large, long, rectangular parietals that contact at the midline and are situated anterior to the supraoccipital; triangular epiotics, with the facet for the dorsal arm of posttemporal centered over the epiotic; hyomandibula head articulating anteriorly with only the pterotic and sphenotic; cleithrum with a long, narrow, straight vertical shaft; mesacoracoid present; and centra with two lateral, elongate fossa. Total length is estimated at 100 cm and age is estimated at 7 years old. We also emend the diagnosis for Apateodus to include more cranial characteristics. Among 37 known genera of Cretaceous aulopiforms, the diversity at the K-Pg boundary is probably underrepresented. Fish skeletons have rarely been recovered from the Bearpaw Formation in Alberta, likely due to a preservational bias. This report, however, shows promise for additional fish material preserved in mosasaur skeletons because they are relatively more commonly preserved than fish skeletons.

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ACKNOWLEDGMENTS

Thanks go to the mining company, Korite International, for their initial discovery of the mosasaur containing the aulopiform specimen, for contacting the Royal Tyrrell Museum for its collection, and for additional field assistance provided by Korite International during the excavation. We thank A. Fotheringham (TMP) for the fine preparation of the new fish material and CMC VP 6941, and M. Mitchell (TMP), who discovered, removed, and made the initial preparation of new fish material. We thank all the following individuals for providing assistance with collections, use of equipment, and laboratory space: B. Brown, R. Arrindell, J. Maisey, and A. Gishlick (AMNH); Z. Johanson, E. Bernard, L. Steel, M. Smith, and M. Richter (NHMUK P); G. Storrs and J. MacKnight (CMC); P. J. Shepherd (BGS [GSM]); D. Bohaska and M. Brett-Surman (USNM); S. McLeod, G. Takeuchi, and V. Rhue (LACM); W. Simpson and L. Grande (FMNH); M. Everhart and R. Zakrzewski (FHSM); M. V. H. Wilson, A. Murray, and J. Bruner (UALVP); and H.-P. Schultze and D. Miao (KUVP). We are grateful for the paleolatitude data provided to us by I. Dalziel and L. Gahagan, PLATES program, University of Texas Institute for Geophysics. M. Caldwell, UALVP, kindly assisted in acquiring a specimen of Apateodus striatus (NHMUK OR.49821). We are grateful for the comments provided to us by M. V. H. Wilson, C. Fielitz, and an anonymous reviewer, and the efforts of the Editors, C. Underwood and M. Friedman, to improve the manuscript. Funding for this project was provided to M.G.N. by Royal Tyrrell Museum Cooperating Society to support postdoctoral research, to T.K. by Government of Alberta Japanese-Canadian Initiative Postdoctoral Fellowship, and also by NSERC Discovery Grant no. 238458 (to M. Caldwell). Seven travel grants were provided to M.G.N. by the Royal Tyrrell Museum Cooperating Society to visit the AMNH, CMC VP, FHSM VP, FMNH, KUVP, LACM, NHMUK P, UALVP, and USNM.