Albertonectes vanderveldei, a new elasmosaur (Reptilia, Sauropterygia) from the Upper Cretaceous of Alberta

ABSTRACT

A new elasmosaurid plesiosaur, Albertonectes vanderveldei, gen. et sp. nov., is described on the basis of an almost complete postcranial skeleton from the upper Campanian, Bearpaw Formation in Alberta, Canada. The new taxon is distinguished by a unique set of characters—76 cervicals, lateral longitudinal ridge on posterior-most cervicals, relatively wide clavicular arch, tapered ventral projection at the median symphysis of coracoids, pointed anterolateral projection of pubis, fused posterior-most caudal vertebrae, and a relatively slender humerus. Ninety-seven chert gastroliths were also recovered with the specimen, and their mean diameters range from <1 to 13.5 cm. Shape analysis indicates that most of the gastroliths were ingested in the vicinity of a beach environment. Evidence that the carcass was scavenged by sharks includes a tooth-marked coracoid, two shed Squalicorax sp. teeth, and small, localized disruptions to the skeleton. Preliminary phylogenetic analysis confirms the inclusion of Albertonectes in a clade comprised of ‘middle’ to Late Cretaceous, long-necked elasmosaurid plesiosaurs. The number of cervical vertebrae associated with different elasmosaur genera does not show any correlation with phylogeny. Both neck and total body length of Albertonectes are the longest among known elasmosaurs, and highlight the morphological extremes attained by this group of plesiosaurs.

ACKNOWLEDGMENTS

We acknowledge the finders of the elasmosaur, M. Parks and R. Cox. The exceptional skills of track-hoe operator R. Cox and those of flat-bed trailer driver H. Larmer, both of G. W. Cox Excavating Ltd., made exposing, removing, and transporting the specimen a relatively easy and safe procedure. We also thank R. Trudel, K. Frenzel, D. Rone, and P. Paré of Korite International for facilitating the removal of TMP 2007.011.0001 from the mine site. We also acknowledge M. Manabe at the National Museum of Nature and Science, Tokyo, for allowing access to the specimen under his care. T. Sato kindly allowed us to use the data matrix from her Ph.D. dissertation. From the staff of TMP we received the following assistance: T. Konishi for the stratigraphic position of the specimen, D. Tanke for the species name, S. Sabrowski for the photographs used in Figures 2 and 3, and M.T.M. was assisted in the preparation of the specimen by D. Macleod, R. Cooke, and J. Graham. T.K. thanks his family and a Government of Canada Post-Doctoral Research Fellowship for financial support. The constructive comments of P. Druckenmiller and B. Wilhelm and the editorial comments of F. R. O’Keefe and P. Barrett improved the manuscript.

Handling editor: Robin O'Keefe