Susumu Konno, Hirofumi Asahi, Christina L. Belanger, Akemi Fukumura, Shyam M. Gupta, Arata Kioka, Kenji M. Matsuzaki, Atsunori Nakamura, Takanori Ojima, Oscar E. Romero, Itsuki Suto, IODP Expedition Scientists
Mesowear analysis of cheek teeth wear is one of the most effective methods in the reconstruction of paleodiet of extinct ungulates. This paper reviews previous studies of mesowear analysis with other reconstructive methods using fossil teeth. This method compares facet development on the occlusal surface of cheek teeth of the fossil specimens with those of extant ungulates to classify into three dietary food habits; grazer, browser, or mixed feeder. The mesowear analysis is relatively cheap and easy method, so it is possible to apply to a large number of fossil teeth specimens in a short period of time. Although most previous studies were focused on fossil specimens, mesowear analysis for extant species is also important for the sake of methodological improvement or basic data collection for fossil study. Applications of detailed mesowear analyses of extant species data, such as sika deer populations in Japan, are useful for the reconstruction of paleodiet.
Foraminifera and Radiolaria have calcareous or siliceous shell, which have been preserved in a long fossil record from the Cambrian. Their sensitivity to environmental changes and morphological variation of the shells in their evolutionary histories allow them to use as good environmental indicator and key fossils through geological time. However, these fossilized organisms are the least studied group regarding molecular and cell-ultrastructural studies, making their phylogenetic position unclear. Recent molecular phylogenetic studies along with thorough cell-ultrastructural studies have greatly changed our understanding of systematics of the eukaryotic "domain". In 1990's, molecular phylogenetic studies of Foraminifera and Radiolaria have been started, and grouped them into the eukaryotic supergroup "Rhizaria". However, the phylogenetic positions of Foraminifera and Radiolaria within Rhizaria were controversial until very recently, when many molecular data of Radiolaria have been accumulated. Based on these data, the "Retaria" hypothesis uniting Foraminifera and Radiolaria, as originally proposed by Cavalier-Smith (1999), was verified. Here, we review the molecular phylogenetic studies of Foraminifera and Radiolaria, and discuss their possible evolutionary scenario from the view of paleontology.