A New Species of Neurankylus from the Milk River Formation (Cretaceous: Santonian) of Alberta, Canada, and a Revision of the Type Species N. eximius

  • Derek W. LarsonEmail author
  • Nicholas R. Longrich
  • David C. Evans
  • Michael J. Ryan
Part of the Vertebrate Paleobiology and Paleoanthropology book series (VERT)


A new species of Neurankylus (N. lithographicus sp. nov.) is described on the basis of skull and shell material from the Santonian-aged Milk River Formation, Alberta, Canada. The genus Neurankylus is also rediagnosed on the basis of the Milk River material and on new material pertaining to the type species N. eximius. N. eximius previously was considered to be a long-lived and cosmopolitan taxon. New Neurankylus material provides insights into the range of morphological variation present in the genus and indicates that many specimens previously referred to N. eximius may belong to different species. The congeners recognized in this chapter have a more restricted geographical and temporal range than has been suggested previously. A new phylogenetic analysis of all known baenid taxa, including all described species of Neurankylus and several basal paracryptodiran taxa of uncertain affinities, yields two important results: a monophyletic Neurankylus is recovered as a basal radiation within Baenidae and parallel evolution is identified among many features previously regarded as synapomorphies for Baenidae. In light of this study and other recent work on turtle systematics, it is now apparent the biogeography and biostratigraphy of Cretaceous turtles may have been more complex than previously appreciated.


Baenidae  Neurankylus Phylogeny Santonian Testudines 



We thank D. Brinkman, P. Currie, M. Wilson, T. Lyson, and the entire UALVP for helpful discussion, resources, and guidance, as well as T. Lyson and W. Joyce for providing the character-taxon matrix for the phylogenetic analysis. Financial support for this research was provided by the Jurassic Foundation and the University of Alberta, Department of Biological Sciences (to DWL), Alberta Ingenuity, National Science Foundation, and Yale Institute for Biospheric Studies (to NRL), National Sciences and Engineering Research Council of Canada Graduate Scholarship and Discovery Grant (to DCE). Specimens were expertly prepared by I. Morrison, J. McCabe, and D. Lloyd. We are grateful to R. Audet for land access permission, the Royal Tyrrell Museum of Palaeontology and the Sloboda family for logistical support, B. Strilisky and T. Lyson for access to specimens, and the 2007 Southern Alberta Dinosaur Research Group field crew for their hard work. This manuscript represents part of DWL’s MSc thesis at the University of Alberta. An earlier version of this manuscript was greatly improved by P. Currie, D. Brinkman, M. Wilson, A. Wolfe, and M. Burns. Reviewers R. Sullivan and T. Lyson and editors D. Brinkman and J. Gardner provided excellent constructive criticism for the improvement of this manuscript. Lastly, we salute Eugene Gaffney for his contributions to baenid research, without which the current study would not have been possible.


  1. Bakker, R. T. (1998). Dinosaur mid-life crisis: The Jurassic–Cretaceous transition in Wyoming and Colorado. New Mexico Museum of Natural History and Science Bulletin, 14, 67–77.Google Scholar
  2. Brinkman, D. B. (2003a). A review of nonmarine turtles from the Late Cretaceous of Alberta. Canadian Journal of Earth Sciences, 40, 557–571.Google Scholar
  3. Brinkman, D. B. (2003b). Anatomy and systematics of Plesiobaena antiqua (Testudines: Baenidae) from the mid-Campanian Judith River Group of Alberta, Canada. Journal of Vertebrate Paleontology, 23, 146–155.Google Scholar
  4. Brinkman, D. B. (2005). Turtles: Diversity, paleoecology, and distribution. In P. J. Currie & E. B. Koppelhus (Eds.), Dinosaur Provincial Park: A spectacular ancient ecosystem revealed (pp. 202–220). Bloomington: Indiana University Press.Google Scholar
  5. Brinkman, D. B., & Nicholls, E. L. (1991). Anatomy and relationships of the turtle Boremys pulchra (Testudines: Baenidae). Journal of Vertebrate Paleontology, 11, 302–315.Google Scholar
  6. Brinkman, D. B., & Nicholls, E. L. (1993). The skull of Neurankylus eximius (Testudines: Baenidae) and a reinterpretation of the relationships of this taxon. Journal of Vertebrate Paleontology, 13, 273–281.Google Scholar
  7. Brinkman, D. B., Stadtman, K., & Smith, D. (2000). New material of Dinochelys whitei Gaffney, 1979, from the Dry Mesa Quarry (Morrison Formation, Jurassic) of Colorado. Journal of Vertebrate Paleontology, 20, 269–274. Google Scholar
  8. Brooks, D. R., Bilewitch, J., Condy, C., Evans, D. C., Folinsbee, K. E., Fröbisch, J., et al. (2007). Quantitative phylogenetic analysis in the 21st century: Progress and prognosis. Revista Mexicana de Biodiversidad, 78, 225–252.Google Scholar
  9. Carpenter, K., & Bakker, R. T. (1990). Part II: A new baenid turtle. Hunteria, 2(6), 3–4.Google Scholar
  10. Cope, E. D. (1877). On reptilian remains from the Dakota beds of Colorado. Proceedings of the American Philosophical Society, 17, 193–196.Google Scholar
  11. Cope, E. D. (1882). Contributions to the history of the Vertebrata of the Lower Eocene of Wyoming and New Mexico, made during 1881. Proceedings of the American Philosophical Society, 20, 139–197.Google Scholar
  12. Doyle, J. A. (1992). Revised palynological correlations of the lower Potomac Group (USA) and the Cocobeach sequence of Gabon (Barremian–Aptian). Cretaceous Research, 13, 337–349.Google Scholar
  13. Dyman, T. S., Tysdal, R. G., Perry, W. J. Jr., Nichols, D. J., & Obradovich, J. D. (1997). Stratigraphy and structural setting of Upper Cretaceous Frontier Formation, western Centennial Mountains, Southwestern Montana and Southeastern Idaho. Cretaceous Research, 29, 237–248.Google Scholar
  14. Eberth, D. A. (2005). The geology. In P. J. Currie & E. B. Koppelhus (Eds.), Dinosaur Provincial Park: A spectacular ancient ecosystem revealed (pp. 54–82). Bloomington: Indiana University Press.Google Scholar
  15. Evans, J., & Kemp, T. S. (1975). The cranial morphology of a new Lower Cretaceous turtle from southern England. Palaeontology, 18, 25–40.Google Scholar
  16. Evans, J., & Kemp, T. S. (1976). A new turtle skull from the Purbeckian of England and a note on the early dichotomies of cryptodire turtles. Palaeontology, 19, 317–324.Google Scholar
  17. Gaffney, E. S. (1972). The systematics of the North American family Baenidae (Reptilia, Cryptodira). Bulletin of the American Museum of Natural History, 147, 1–319.Google Scholar
  18. Gaffney, E. S. (1975). A phylogeny and classification of the higher categories of turtles. Bulletin of the American Museum of Natural History, 155, 389–436.Google Scholar
  19. Gaffney, E. S. (1979). The Jurassic turtles of North America. Bulletin of the American Museum of Natural History, 162, 1–135.Google Scholar
  20. Gaffney, E. S., & Hiatt, R. (1971). A new baenid turtle from the Upper Cretaceous of Montana. American Museum Novitates, 2443, 1–9.Google Scholar
  21. Gaffney, E. S., & Meylan, P. A. (1988). A phylogeny of turtles. The Systematics Association Special Volume, 35A, 157–219.Google Scholar
  22. Gilmore, C. W. (1916). Vertebrate faunas of the Ojo Alamo, Kirtland, and Fruitland formations. U. S. Geological Survey, Professional Paper, 98Q, 279–308.Google Scholar
  23. Gilmore, C. W. (1919). New fossil turtles, with notes on two described species. Proceedings of the U. S. National Museum, 56, 113–132.Google Scholar
  24. Gilmore, C. W. (1935). On the Reptilia of the Kirtland Formation of New Mexico, with descriptions of new species of fossil turtles. Proceedings of the United States National Museum, 83, 159–188.Google Scholar
  25. Goodwin, M. B., & Deino, A. L. (1989). The first radiometric ages from the Judith River Formation (Upper Cretaceous), Hill County, Montana. Canadian Journal of Earth Sciences, 26, 1384–1391.Google Scholar
  26. Gradstein, F. M., Ogg, J. G., & Smith, A. G. (2004). Construction and summary of the geologic time scale. In F. M. Gradstein, J. G. Ogg, & A. G. Smith (Eds.), A geologic time scale (pp. 455–464). Cambridge: Cambridge University Press.Google Scholar
  27. Hay, O. P. (1908). The fossil turtles of North America. Washington, DC: Carnegie Institute.Google Scholar
  28. Holroyd, P. A., & Hutchison, J. H. (2002). Patterns of geographic variation in latest Cretaceous vertebrates: Evidence from the turtle component. In J. H. Hartman, K. R. Johnson & D. J. Nichols (Eds.), The Hell Creek Formation and Cretaceous-Tertiary Boundary in the Great Plains: An integrated continental record of the end of the Cretaceous (pp. 177–190). The Geological Society of America, Special Paper 361.Google Scholar
  29. Hutchison, J. H. (1984). Determinate growth in the Baenidae (Testudines): Taxonomic, ecologic, and stratigraphic significance. Journal of Vertebrate Paleontology, 3, 148–151.Google Scholar
  30. Hutchison, J. H., & Archibald, J. D. (1986). Diversity of turtles across the Cretaceous/Tertiary boundary in northeastern Montana. Palaeogeography, Palaeoclimatology, Palaeoecology, 55, 1–22.Google Scholar
  31. Hutchison, J. H., & Holroyd, P. A. (2003). Late Cretaceous and early Paleocene turtles of the Denver Basin, Colorado. Rocky Mountain Geology, 38, 121–142.Google Scholar
  32. Jacobs, L. L., Winkler, D. A., & Murry, P. A. (1991). On the age and correlation of Trinity mammals, Early Cretaceous of Texas, USA. Newsletter of Stratigraphy, 24, 35–43.Google Scholar
  33. Joyce, W. G. (2007). Phylogenetic relationships of Mesozoic turtles. Bulletin of the Peabody Museum of Natural History, 48, 3–102.Google Scholar
  34. Lambe, L. M. (1902). New genera and species from the Belly River Series (mid-Cretaceous). Contributions to Canadian Palaeontology, 3, 23–81.Google Scholar
  35. Leahy, G. D., & Lerbekmo, J. F. (1995). Macrofossil magnetobiostratigraphy for the upper Santonian—lower Campanian interval in the Western Interior of North America: Comparisons with European stage boundaries and planktonic foraminiferal zonal boundaries. Canadian Journal of Earth Sciences, 32, 247–260.Google Scholar
  36. Leidy, J. (1870). Descriptions of Emys jeanesi, E. haydeni, Baena arenosa, and Saniwa ensidens. Proceedings of the Academy of Natural Sciences of Philadelphia, 1870, 123–124.Google Scholar
  37. Linnaeus, C. (1758). Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis, Tomus I, Editio Decima. Stockholm: Holmiae.Google Scholar
  38. Lipka, T. R., Therrien, F., Weishampel, D. B., Jamniczky, H. A., Joyce, W. G., Colbert, M. W., et al. (2006). A new turtle from the Arundel clay facies (Potomac Formation, Early Cretaceous) of Maryland, U.S.A. Journal of Vertebrate Paleontology, 26, 300–307.Google Scholar
  39. Lyson, T. R., & Joyce, W. G. (2009a). A new species of Palatobaena (Testudines: Baenidae) and a maximum parsimony and bayesian phylogenetic analysis of Baenidae. Journal of Paleontology, 83, 457–470.Google Scholar
  40. Lyson, T. R., & Joyce, W. G. (2009b). A revision of Plesiobaena (Testudines: Baenidae) and an assessment of baenid ecology across the K/T boundary. Journal of Paleontology, 83, 833–853.Google Scholar
  41. Lyson, T. R., & Joyce, W. G. (2010). A new baenid turtle from the Upper Cretaceous (Maastrichtian) Hell Creek Formation of North Dakota and a preliminary taxonomic review of Cretaceous Baenidae. Journal of Vertebrate Paleontology, 30, 394–402.Google Scholar
  42. Meek, F. B., & Hayden, F. V. (1862). Descriptions of new lower Silurian (Primordial), Jurassic, Cretaceous, and Teriery fossils collected in the Nebraska Territory, with some remarks on the rocks from which they were obtained. Proceedings of the Academy of Natural Sciences of Philadelphia, 13, 415–447.Google Scholar
  43. Milner, A. R. (2004). The turtles of the Purbeck Limestone Group of Dorset, Southern England. Palaeontology, 47, 1441–1467.Google Scholar
  44. Nopcsa, F. (1923). On the geological importance of the primitive reptilian fauna of the uppermost Cretaceous of Hungary; with a description of a new tortoise (Kallokibotion). Quarterly Journal of the Geological Society, 79, 100–116.Google Scholar
  45. Ogg, J. G., & Smith, A. G. (2004). The geomagnetic polarity time scale. In F. M. Gradstein, J. G. Ogg, & A. G. Smith (Eds.), A geologic time scale (pp. 63–86). Cambridge: Cambridge University Press.Google Scholar
  46. Ogg, J. G., Agterberg, F. P., & Gradstein, F. M. (2004). The Cretaceous Period. In F. M. Gradstein, J. G. Ogg, & A. G. Smith (Eds.), A geologic time scale (pp. 344–383). Cambridge: Cambridge University Press.Google Scholar
  47. Parks, W. A. (1933). New species of dinosaurs and turtles from the Upper Cretaceous formations of Alberta.University of Toronto Studies, Geological Series, 31, 3–33.Google Scholar
  48. Payenberg, T. H. D., Braman, D. R., Davis, D. W., & Miall, A. D. (2002). Litho- and chronostratigraphic relationships of the Santonian–Campanian Milk River Formation in southern Alberta and Eagle Formation in Montana utilizing stratigraphy, U-Pb geochronology, and palynology. Canadian Journal of Earth Sciences, 39, 1553–1577.Google Scholar
  49. Reeside, J. B. (1927). Cephalopods from the lower part of the Cody Shale of Oregon Basin, Wyoming. U.S. Geological Survey Professional Paper, 150A, 1–19.Google Scholar
  50. Rogers, R. R. (1998). Sequence analysis of the Upper Cretaceous Two Medicine and Judith River formations, Montana: A nonmarine response to the Claggett and Bearpaw marine cycles. Journal of Sedimentary Research, 68, 615–631.Google Scholar
  51. Ronquist, F., & Huelsenbeck, J. P. (2003). MrBayes 3: Bayesian phylogenetic inference under mixed models. Bioinformatics, 19, 1572–1574.Google Scholar
  52. Sullivan, R. M., & Lucas, S. G. (2006). The Kirtlandian land-vertebrate “age”—faunal composition, temporal position and biostratigraphic correlation in the nonmarine Upper Cretaceous of Western North America. New Mexico Museum of Natural History and Science Bulletin, 35, 7–29.Google Scholar
  53. Sullivan, R. M, Lucas, S. G., Hunt, A. P., & Fritts, T. H. (1988). Colour pattern on the selmacryptodiran turtle Neurankylus from the early Paleocene (Puercan) of the San Juan Basin, New Mexico. Natural History Museum of Los Angeles County Contributions in Science, 401, 1–9.Google Scholar
  54. Sullivan, R. M., Jasinski, S. E., & Lucas, S. G. (2012). Re-assessment of late Campanian (Kirtlandian) turtles from the Upper Cretaceous Fruitland and Kirtland Formations, San Juan Basin, New Mexico, USA. In D. B. Brinkman, P. A. Holroyd, & J. D. Gardner (Eds.), Morphology and evolution of turtles. Dordrecht: Springer.Google Scholar
  55. Swofford, D. L. (2001). PAUP*: Phylogenetic analysis using parsimony (* and other methods) version 4.0b10 edition. Sunderland: Sinauer Associates.Google Scholar
  56. Williams, E. E. (1950). Variation and selection in the cervical central articulations of living turtles. Bulletin of the American Museum of Natural History, 94, 505–562.Google Scholar
  57. Wiman, C. (1933). Über Schildkröten aus der Oberen Kreide in New Mexico. Nova Acta Regiae Societatis Scientiarum Upsaliensis, 9, 1–34.Google Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Derek W. Larson
    • 1
    Email author
  • Nicholas R. Longrich
    • 2
  • David C. Evans
    • 3
  • Michael J. Ryan
    • 4
  1. 1.University of Alberta Laboratory for Vertebrate PaleontologyUniversity of AlbertaEdmontonCanada
  2. 2.Department of Geology and GeophysicsYale UniversityNew HavenUSA
  3. 3.Department of Natural History (Palaeobiology)Royal Ontario MuseumTorontoCanada
  4. 4.Cleveland Museum of Natural History, 1 Wade Oval DriveUniversity CircleClevelandUSA

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