The calcareous nannofossil biostratigraphy of Lower Cretaceous sediments cored at ODP Site 1149 allows identification of the C. oblongata and the L. bollii Zones of Thierstein (1971, 1973). The continuous occurrence of L. bollii is reported for the first time in sediments from the Pacific Ocean. On the contrary, other marker species regarded as cosmopolitan (e.g., C. oblongata) have a sporadic occurrence at this site. Nannoconids, very useful zonal markers in Tethyan sections, are virtually absent at this site, preventing enhanced biostratigraphic resolution. Occurrence of unusually high abundances of D. lehmanii is also recorded and correlates with the prominent Early Cretaceous 
13C positive excursion (A. Bartolini, pers. comm., 2001). Continuous and spot-coring in Holes 1149B and 1149C, respectively, allow identification of the first occurrence of R. terebrodentarius just above the first occurrence of L. bollii. As these two bioevents correlate to the upper and lower Hauterivian, respectively, a condensed section or an unconformity occurs at this depth (310
mbsf).
