Late Cretaceous Notogoneus from microvertebrate assemblages of the Dinosaur Park Formation, Campanian of southern Alberta, Canada, and insight into the ecology and evolution of early gonorynchids

ABSTRACT

We here report the first documented occurrence of a gonorynchiform from the Mesozoic of Canada, represented by disarticulated material recovered from multiple localities in the Lethbridge Coal Zone, in the Late Cretaceous Campanian upper Dinosaur Park Formation of southern Alberta. Despite the preservation of these specimens as disarticulated and isolated microvertebrate material, we can identify this fish as the gonorynchid Notogoneus. Although this material was recovered from estuarine settings, the local environment was freshwater, and this occurrence does not constitute evidence that this species of Notogoneus was amphidromous, as has previously been hypothesized for early gonorynchids. We offer suggestions regarding the whole-body anatomy of the fish represented in our sample through comparisons with articulated specimens of Notogoneus osculus from the Green River Formation as well as with modern comparative material. Such details include a narrow mouth in a ventral position and probable possession of branchial tooth plates, from which aspects of the ecology of this fish can be deduced, such as durophagy and a probable demersal environmental preference. Additionally, these comparisons highlight the mosaic evolution of early gonorynchids, combining a primitively chanid-like vertebral anatomy and a more derived, Gonorynchus-like jaw.

ACKNOWLEDGMENTS

We thank A. Stewart (Museum of New Zealand Te Papa Tongerawa) for the donation of Gonorynchus forsteri specimen TMP 2015.030.0003, without which a large part of this study would not have been possible. We also thank T. Tirnski and S. Tassell (Auckland War Memorial Museum, Auckland) and K. Seymour (Royal Ontario Museum, Toronto) for the loan of several comparative specimens. We thank T. Courtenay and R. Sanchez, for assistance in getting access to further comparative material; T. Argyriou, O. Kovalchuk, J. Liu, R. Nagesan, T. Přikryl, O. Vernygora, and A. Wendruff, for their assistance in getting access to various publications; and J. Sanchez, for his assistance in the preparation of Notogoneus osculus specimen TMP 2014.005.0021. We thank all of the collectors and sorters of this material, including K. Aulenbach, J. Maccagno, C. van Mackelberg, S. Marsland, V. Lam, and the many volunteering members of the Alberta Palaeontological Society and participants of the Royal Tyrrell Museum of Palaeontology Day Digs, too numerous to mention here individually. We also thank JVP editors C. Underwood and J. Kriwet, as well as two anonymous reviewers for their helpful comments and suggestions on the manuscript.

ORCID

Julien D. Divay http://orcid.org/0000-0001-8581-2056