Revision of the Mesozoic fossil wood record for Eastern Asia led to the recognition of a new type of homoxylous wood radial pitting, called here “the japonicum type”. This anatomical feature has a limited distribution in both time and space. On this basis a new genus, Shimakuroxylon gen. nov., is recognized. It has limited biostratigraphical interest, ranging from the Jurassic to the Cretaceous. Paleogeographically, however, it is bound to these terranes which lined southernmost Eastern Asia during the Jurassic (Lhasa, Indochina, Semitau, etc.). Being also found in the Outer Zone of Southwest Japan, the origin of which is still a matter of debate, Shimakuroxylon points out a southern cradle for this tectonic unit. The genus distribution also suggests it is an indicator for warm and wet climates.