Late Jurassic tropical Radiolaria: Vallupus and its related forms

The Vallupinae is a radiolarian subfamily whose range is restricted to the Late Jurassic and the acme in the latest Jurassic (Tithonian). Species of the subfamily (Vallupus group) are found in low- and middle-latitudes of the western Pacific, East Asia, North-Central-South America, and Mediterranean regions. Available paleomagnetic data suggest that Vallupus group-bearing rocks in these localities accumulated within 25° of the Jurassic paleoequator. er temperature is considered to be the major factor controlling the distribution of the Vallupus group. Warm seawater temperatures could be favourable to the propagation of the group. The Vallupus territory is proposed as a water mass inhabited by the Vallupus group. It occupied tropical surface waters from the low-latitude part of the Panthalassa to Tethys. Some Vallupus group-bearing rocks in the Circum-Pacific orogenic belt have been translated from low-latitude depositional sites to higher locations by lateral plate movements. pper Jurassic strata in Japan accumulated outside the Vallupus territory. This means that the Vallupus group cannot be utilized for Upper Jurassic radiolarian zonal correlations between Japan and other regions. However, the rapid speciation of the Vallupus group has a high potential to produce a fine biostratigraphic framework for the Upper Jurassic within the Vallupus territory.