July 22 , 2016

A biostratigraphic organization of the Cretaceous nonmarine turtle record provides valuable insight into turtle evolutionary events. Five biostratigraphic datums based on Cretaceous turtle distribution are identified: Barremian, Aptian/Albian, Albian/Cenomanian, Turonian, Santonian/Campanian and the K/T boundary. The Barremian encompasses the lowest occurrences of Lindholemydidae, Dortokidae, Podocnemoidea, Nanhsiungchelydae, and Trionychidae, marking a major increase in turtle diversity. The Aptian/Albian datum is marked by the lowest occurrences of Bothremydidae and Baenidae. The Albian/Cenomanian datum is the highest occurrence of Xinjiangchelyidae, Araripemydidae, and Euraxemydidae. The Turonian datum is marked by the first occurrence of Macrobaenidae and Chelydridae in North America. The Santonian/Campanian datum is marked by the lowest occurrence of Compsemydidae. Further, this is the highest occurrence of Sinemydidae. The K/Pg datum is marked by the highest occurrences of Nanhsiungchelydae, Kallokibotionidae, and Solemydidae. The dispersal of bothremydids to South America and Africa is hypothesized to be the result of a lowering of global sea level. This may also explain the immigration of trionychoideans into North America at a similar time. Further, macrobaenid appearance in North America also falls within the temporal uncertainty of the bothremydid and trionychoidean migrations, so these may represent one event.

Asher J. Lichtig and Spencer G. Lucas (2016)

Cretaceous nonmarine turtle biostratigraphy and evolutionary events.

in Khosla, A. and Lucas, S.G., eds., 2016, Cretaceous Period: Biotic Diversity and Biogeography. New Mexico Museum of Natural History and Science Bulletin 71: 185-194