The record of Bennettitales from west-central Argentina and southern Brazil in South America is among the oldest known. In contrast to the better known near-coastal assemblages from the Northern Hemisphere, these Gondwanic elements are restricted to continental areas and isolated rift basins, similar to those in South Africa. Williamsonia potyporanae sp. nov. is preserved by impressions that expose distinct longitudinal sections of the ovulate structure, allowing the reconstruction of its tridimensional aspect, and is accompanied by probable Pterophyllum leaves. It consists of an ovate-shaped flower covered by two layers of delicate and connected ribbon-shaped and hairy bracts, and an obconic receptacle supporting a great number of megasporophylls, with uniformly aligned and apical fusiform ovules or seeds. The bennettite remains are part of an autochtonous-parautochtonous floral assemblage dominated by conifers and restricted to a thin mudstone interval in a mainly fluvial deposition comprisig the Caturrita Formation. The mud interval suggests a shallow lake supplied by periodic, intense rainfall that affected the vegetation growing along the river banks and/or on a floodplain deposits. An initially proposed Norian age, based on diversified vertebrate remains found in lower levels (Ictidosaur or Mammaliamorpha Cenozone), was recently extended to the Rhaetian. The advanced morphology of ovulate structure described here suggest an even younger Jurassic age, supported by comparisons with other fossil assemblages, mainly those from Argentine basins.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 50 • No. 1