ABSTRACT. Sauropod dinosaurs are poorly represented in the Lower Cretaceous of eastern Asia. Here, we describe a number of isolated sauropod teeth from the Kuwajima Formation (?Berriasian±?Hauterivian) of Shiramine, Japan. The mosaic of shared derived characters and symplesiomorphies displayed by the teeth indicate that they are referable to a basal member of the titanosauriform radiation. A taxonomic review of previously described sauropod specimens from eastern and south-eastern Asia reveals that a diversity of sauropods (including a titanosaurian, a basal titanosauriform and a ?euhelopodid, as well as several forms of indeterminate systematic position) was present in this region in the Early Cretaceous. This diversity con¯icts with previous suggestions that eastern Asia was biogeographically isolated from the rest of Laurasia until the late Early Cretaceous and that the sauropod fauna was limited to the endemic East Asian clade Euhelopodidae. The presence of titanosauriform sauropods in the basal Cretaceous of Japan and Thailand indicate that the proposed faunal isolation of eastern Asia ended approximately 20 myr earlier than usually suggested.

Platynotan lizards underwent a dramatic Late Cretaceous radiation into marine habitats. Beginning with small-bodied forms, the lineage culminated with the mosasaurs, large predatory lizards with a world-wide distribution in the Santonian-Campanian. Moreover, the marine squamate radiations of the Cenomanian-Turonian are remarkable in having produced a range of long-bodied, reduced-limbed swimmers (dolichosaurs, adriosaurs, coniasaurs and limbed snakes) that seem to have thrived in the shallow coastal environments of the Western Tethys region. Until now, none of these long-bodied aquatic squamates has been recorded prior to the Cenomanian, none has been recovered from a non-marine locality and none is known from Asia. Here we describe a small, gracile, long-bodied mosasauroid lizard from a swampy continental deposit in the Lower Cretaceous of Japan.

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