Corystospermaceae
[2][3] They were first described based on fossils collected by Hamshaw Thomas from the Burnera Waterfall locality near the Umkomaas River of South Africa.[4] Corystosperms are typified by a group of plants that bore forked Dicroidium leaves, Umkomasia cupulate ovulate structures and Pteruchus pollen organs, which grew as trees that were widespread over Gondwana during the Middle and Late Triassic.Other fossil Mesozoic seed plants with similar leaf and/or reproductive structures have also sometimes been included within the "corystosperm" concept sensu lato, such as the "doyleoids" from the Early Cretaceous of North America and Asia.[12] During the Middle-Late Triassic, Dicroidium bearing corystosperms were widespread and dominant trees over temperate areas of southern Gondwana (including the Indian subcontinent, South America, Southern Africa, Antarctica, Australia and New Zealand) including wetland and forest environments, where they formed part of the canopy vegetation.[19] In light of this issue, Petriella (1981) proposed two solutions: either retain Corystospermaceae as a nomen conservandum, or replace it with a new name, Umkomasiaceae.