Abstract Today and in the Tertiary, the geographical distribution of castorids is limited throughout all of the northern continents. Fossils of the Castoridae genus Steneo- fiber are abundant in many localities of Eurasia from the late Oligocene to Pliocene period. Recently, Steneofiber fossils were discovered in two localities of northern Thailand, Mae Moh and Chiang Muan coal mines, in layers of late middle Miocene age. These discoveries represent the first records of castorids from Southeast Asia and correspond to their southernmost known range. The focus of this study is to describe this new Thai species of Steneofiber and to define its wear stages from the molar occlusal surfaces by using micro-CT scan analysis. The CT scan technique permits the analysis of the virtual occlusal surface changes from wear,
Communicated by: Robert Asher
Electronic supplementary material The online version of this article (doi:10.1007/s00114-011-0769-0) contains supplementary material, which is available to authorized users.
K. Suraprasit (*) : J.-J. Jaeger
Institut International de Paléoprimatologie et Paléontologie Humaine: Evolution et Paléoenvironnements (IPHEP, UMR CNRS 6046), Université de Poitiers,
40 Avenue du Recteur Pineau,
86022 Poitiers Cedex, France
e-mail: suraprasit@gmail.com
Y. Chaimanee
Paleontology Section, Geological Survey Division, Department of Mineral Resources,
Rama VI Road,
Bangkok 10400, Thailand
T. Martin
Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Universität Bonn,
Nussallee 8,
53115 Bonn, Germany
allowing easier comparison to related species of Steneofiber cheek teeth without destroying the teeth. The new species, Steneofiber siamensis n. sp., can be distinguished from the other species of Steneofiber by several distinct characters, longer mesostriid on p4, presence of premesostria and metastria on P4, which are smaller than most of the other known species. The occurrence of this new castorid also supports a subtropical to tropical paleoclimate for these two localities of northern Thailand.