A new Early Cretaceous coelacanth from Texas

Abstract

Coelacanths have a long fossil record spanning from Early Devonian to the present globally, but until now only from Permian and Triassic sediments in Texas. Reported here is a partial skull, including an articulated lower jaw and disarticulated cranial elements, of a new coelacanth fish (Sarcopterygii: Actinistia) from the Early Cretaceous (Albian) of northern Texas. The presence of a single large pore opening for the supraorbital sensory canal, lack of ornamentation of the cheek and opercular bones, the presence of a few large pore openings in the cheekbones (five or less in the lachrymojugal, one in the other cheekbones) and the presence of small teeth are characters placing this specimen within a new clade along with the genera Libys, Ticinepomis and Diplurus. An upturned symphysis, unornamented gular plates whose posterior margins taper to points, and angular with sinuous dorsal edges reaching the same dorsal extent as the dentary are characters that make this specimen morphologically unique among the new clade. This specimen represents a new species here named as Reidus hilli.

Keywords:

• coelacanth
• Cretaceous
• actinistia
• Duck Creek Formation

Acknowledgements

I thank Robert Reid for discovering and donating SMU 76592 to the Shuler Museum. I thank Dr. Louis Jacobs and Dr. Dale Winkler for allowing me access to the specimen and for their guidance throughout this project. I thank Michael Polcyn, Thomas Adams and Brian Andres for providing insights into the methods used in this study. Funding for this project was provided by the Institute for the Study of Earth and Man at Southern Methodist University.