Cenomanian-Campanian (Late Cretaceous) mid-palaeolatitude sharks of Cretalamna appendiculata type
The type species of the extinct lamniform genus Cretalamna, C. appendiculata, has been assigned a 50 Ma range (Albian–Ypresian) by a majority of previous authors. Analysis of a partly articulated dentition of a Cretalamna from the Smoky Hill Chalk, Kansas, USA (LACM 128126) and isolated teeth of the genus from Cenomanian to Campanian strata of Western Australia, France, Sweden, and the Western Interior of North America, indicates that the name of the type species, as applied to fossil material over the last 50 years, represents a large species complex. The middle Cenomanian part of the Gearle Siltstone, Western Australia, yielded C. catoxodon sp. nov. and “Cretalamna” gunsoni. The latter, reassigned to the new genus Kenolamna, shares several dental features with the Paleocene Palaeocarcharodon. Early Turonian strata in France produced the type species C. appendiculata, C. deschutteri sp. nov., and C. gertericorum sp. nov. Cretalamna teeth from the late Coniacian part of the Smoky Hill Chalk in Kansas are assigned to C. ewelli sp. nov., whereas LACM 128126, of latest Santonian or earliest Campanian age, is designated as holotype of C. hattini sp. nov. Early Campanian deposits in Sweden yielded C. borealis and C. sarcoportheta sp. nov. A previous reconstruction of the dentition of LACM 128126 includes a posteriorly situated upper lateroposterior tooth, with a distally curved cusp, demonstrably misplaced as a reduced upper “intermediate” tooth. As originally reconstructed, the dentition resembled that of cretoxyrhinids (sensu stricto) and lamnids. Tooth morphology, however, indicates an otodontid affinity for Cretalamna. The root is typically the most diagnostic feature on an isolated Cretalamna tooth. This porous structure is commonly abraded and/or corroded and, consequently, many collected Cretalamna teeth are indeterminable at species level.
Key words: Lamniformes, Otodontidae, Cretaceous, Australia, France, Sweden, USA.
Mikael Siversson [firstname.lastname@example.org], Department of Earth and Planetary Sciences, Western Australian Museum, 49 Kew Street, Welshpool, WA 6106, Australia; Johan Lindgren [email@example.com], Department of Geology, Lund University, Sölvegatan 12, SE-223 62 Lund, Sweden; Michael G. Newbrey [firstname.lastname@example.org], Department of Biology, Columbus State University, Co-lumbus, Georgia 31907-5645, USA; Royal Tyrrell Museum of Palaeontology, Box 7500, Drumheller, Alberta, T0J 0Y0, Canada; and Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada; Peter Cederström [email@example.com], Axelvoldsvägen 27, SE-241 35 Eslöv, Sweden; Todd D. Cook [firstname.lastname@example.org], School of Science, Penn State Erie, The Behrend College, 4205 College Drive, Erie, PA 16563, USA.