Nuevos registros para la xilotafoflora de la Formación Yaguarí, Pérmico Superior de Uruguay

Abstract

Some new gymnospermous woods from the Yaguari Formation from several sites of the Department Cerro Largo in northern Uruguay are described. They are Ginkgophytoxylon lucasii Tidwell & Munzing, Australoxylon duartei (Salviano Japiassu) Marguerier, Zalesskioxylon jamudhiense (Maheshwari) Lepekhina, and Planoxylon gnaedingeriae Crisafulli sp. nov. The three last species only show picnoxylic secondary wood, while the former also has a homogeneous pith. Ginkgophytoxylon lucasii was found in Lower Permian of the Hueco Formation (New Mexico), Zalesskioxylon jamudhiense in the Kamthi Formation (India) and Australoxylon duartei in the Morro Pelado Formation (Brasil), the last two of Upper Permian age. Planoxylon has the largest stratigraphic distribution, from Permian (India) to Cretaceous (New Zealand), including extra-gondwanaland species. This is the first record of this genus for the Permian of South America. It differs from the other species of Planoxylon because of its septa and pits on the tracheidal walls and horizontal walls of the rays. The presence of Ginkgoales in the Yaguari Formation is confirmed by Ginkgophytoxylon lucasii and Baieroxylon cicatricum. The anatomy characters of Yaguari Formation woods show a combination between araucarioid type and mixed-abietinoid. Therefore, it is confirmed the Upper Permian age assigned to the Yaguarí Formation.