Basilemys sinuosa Hay, 1902

Remarks

• Collection:    Lee Garrison

• Formation:   Montana Group, Hell Creek Formation

• Location:      County, Montana

• Data compiled by Lee Garrison

• Here are some additional comments from the webmaster:

• Our opinion is that Basilemys sinuosa Hay and B. variolosa Hay are indeed separate, valid species.  However, distinguishing between the two species requires an expertise that we do not possess.  The post cranial material seems indistinguishable from our perspective.

• Basilemys sinuosa is reported to be restricted to the Maastrichtian, whereas variolosa is restricted to the Campanian.

• Our specific assignment of Lee's Basilemys tibia is based on horizon.

General Info

Synonyms (older names and misidentifications in the literature)

• Synonymy contains references to both variolosa and sinuosa.

• Freshwater turtle

• 1902 Basilemys sp. Hay

• 1935 Basilemys sp. Hay; Gilmore

• 1956 Basilemys sp. Hay; Langston

• 1964 Basilemys sp. Hay; Estes

• 1972 Basilemys sp. Hay; Sahni

• 1989 Basilemys sp. Hay; Bryant

• 1993 Basilemys sp. Hay; Brinkman & Nicholls

• 1998 Basilemys sp. Hay; Brinkman

• 2001 Basilemys sp. Hay; Peng, Russell & Brinkman

• 2004 Basilemys sp. Hay; Joyce, Parham & Gauthier

Stratigraphic Occurrence

• Judith River Group, Judith River Formation of Montana (variolosa)

• Montana Group, Hell Creek Formation of South Dakota and Montana (sinuosa)

• Montana Group, Lance Formation of Wyoming (sinuosa)

• Edmonton Group, Scollard Formation of Alberta, Canada (sinuosa)

• Edmonton Group, Dinosaur Park Formation of Alberta, Canada (sinuosa)

• Judith River Group, Foremost Formation of Alberta, Canada (variolosa)

• Judith River Group, Oldman Formation of Alberta, Canada (variolosa)

• Montana Group Equivalent, Fruitland Formation of northwestern New Mexico (sinuosa)

• Montana/Edmonton Group Equivalent, Frenchman Formation of Saskatchewan (sinuosa)

Age

• Basilemya sinuosa Hay ranges from the middle Maastrichtian to the end of the Maastrichtian where it died out at the K-T boundary (~67-65 mya).  For reference, B. variolosa Hay ranges from the Middle to Late Campanian Stage (~75-71 mya).

Geographic Occurrence

• Alberta, Canada

• Carter County, Montana

• Harding County, South Dakota

• Hill County, Montana

• Niobrara County, Wyoming

• San Juan County, New Mexico

Remarks

           For photographs and more information on Basilemys (several species) see:

• Brinkman, D. B.; Nicholls, E. L.  1993.  New specimen of Basilemys praeclara Hay and its bearing on the relationships of the Nanhsiungchelyidae (Reptilia: Testudines).  Journal of Paleontology 67, 1027-1031.

• Brinkman, D. B. 1998.  The skull and neck of the Cretaceous turtle Basilemys (Trionychoidea, Nanhsiungchelyidae), and the interrelationships of the genus.  Paludicola 10, 1-157.

• Brinkman, D. B.  2003.  A review of the nonmarine turtles from the Late cretaceous of Alberta.  Canadian Journal of Earth Sciences 40, 557-571.

• Bryant, L. J. 1989. Non-dinosaurian lower vertebrates across the Cretaceous-Tertiary boundary in northeastern Montana. University of California Publications in Geological Sciences 134, 1-107.

• Estes, R.  1964.  Fossil vertebrates from the Late Cretaceous Lance Formation, eastern Wyoming. University of California Publications in Geological Sciences 49, 1-180.

• 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(2978), 159-188.

• Hay, O. P.  1902.  Description of two species of extinct tortoises, one new. Proceedings of the Academy of Natural Sciences of Philadelphia 54, 383-388.

• Hay, O. P.  1908.  The fossil turtles of North America.  Carnegie Institute of Washington 75, 1-568.

• Hutchison, J. H., and J. D. Archibald. 1986. Diversity of turtles across the Cretaceous/Tertiary Boundary in Northeastern Montana. Palaeogeography, Palaeoclimatology, Palaeoecology 55, 1-22

• Joyce, W. G., Parham, J. F., & Gauthier, J. A.  2004. Developing a protocol for the conversion of rank-based taxon names to phylogenetically defined clade names, as exemplified by turtles. Journal of Paleontology 78(5), 989-1013.

• Langston, W. Jr.  1956.  The shell of Basilemys variolosa (Cope). Bulletin of the National Museum of Canada 147, 155-163.

• Peng, J., Russell, A. P., & Brinkman, D. B.  2001. Vertebrate microsite assemblages (exclusive of mammals) from the Foremost and Oldman Formations of the Judith River Group (Campanian) of southeastern Alberta: an illustrated guide. Provincial Museum of Alberta, Natural History Occasional Paper 25, 1-546.

• Riggs, E. S.  1906.  The carapace and plastron of Basilemys sinuosus, a new fossil tortoise from the Laramie beds of Montana.  Field Columbian Museum Publications 110, Geological series 2(7), 249-256.

• Robertson, D. S.; McKenna, M. C.; Toon, O. B.; Hope, S.; Lillegraven, J. A.  2004.  Survival in the first hours of the Cenozoic.  Geological Society of America Bulletin 116 (5/6), 760-768. 

• Sahni, A.  1972.  The vertebrate fauna of the Judith River Formation, Montana.  Bulletin of the Museum of Natural History 147(6), 321-412.