New gymnosperm wood fossils, a seed-ovule structure, and a new generic affinity to Cedroxylon canoasense Rau from the Permian and Triassic–Jurassic of Southern Brazil

Abstract

Two new species of gymnosperm wood from the Triassic-Jurassic of Brazil are here described [Lobatoxylon kaokense Kräusel and Chapmanoxylon jamuriense (Maheswari) Pant & Singh], and a new age and generic affinity are proposed for Cedroxylon canoasense Rau. To the latter, originally considered as Triassic, an early Permian age is proposed based on its lithological relationships and the location of its discovery. Additionally, a seed-ovule structure linked to Kaokoxylon zalesskyi (Sahni) Maheswari wood materials, is illustrated and analyzed. All materials were identified in the sedimentary rocks exposed in the central E-W belt (Central Depression) of the State of Rio Grande do Sul, South Brazil, where is exposed the Gondwana Sequence of Paraná Basin. The new wood taxa here described increase the number of known genera in the Triassic-Jurassic of southern Brazil. Nevertheless, the arboreal vegetation of gymnosperms remains impoverished when compared with that present in the Permian deposits. Survivors from the Permian-Triassic extinction, they show that new and more evolved types were capable to explore and adapt to the new landscapes resulting from the environmental changes that affected the interior continental areas of Western Gondwana.

Phylogeny and divergence time estimation of the genus Didymodon (Pottiaceae) based on nuclear and chloroplast markers

“…This means that the Earth's oldest Pottiaceae species should have an origin before the early Cretaceous. Plant fossils can provide a very important scientific foundation to explore species evolution (Grolle & Heinrichs, 2003; Wignall & Bond, 2008; Crisafulli et al, 2018). But the formation and preservation of fossils are related to the physiological–ecological characteristics of species and are inseparable from the surrounding environment.…”

“…It is well documented that plant fossils can provide a very important scientific foundation for exploring species evolution and reconstructing the ancient climatic environment (Grolle & Heinrichs, 2003; Wignall & Bond, 2008; Crisafulli et al, 2018), and previous studies have shown that bryophytes originated from the equatorial low latitude region in the early Paleozoic Era (Yang et al, 2004; Kou et al, 2012). The differentiation between mosses and liverwort took place in the Ordovician period or even earlier (Hernick et al, 2008; Guo et al, 2012).…”

Xylotafofloristics studies from the Llantenes Formation, Upper Triassic, Mendoza, Argentina.

“…Consecuentemente, este ejemplar puede ser albergado en ese taxón fósil que está distribuido en Gondwana desde el Pérmico al Triásico Superior con numerosas especies (Crisafulli & Herbst, 2008;Crisafulli et al, 2018).…”

“…Las punteaduras en los campos de cruzamiento de una a cinco permiten acercarnos a Chapmanoxylon jamuriense. Este taxón es citado para el Pérmico de las formaciones Raniganj de la India (Pant & Singh, 1987), Solca de Argentina (Crisafulli & Herbst, 2008), Tacuary de Paraguay (Leiva Verón et al, 2012) y Tres Islas de Uruguay (Crisafulli et al, 2009), y para el Triásico de la Formación Caturrita, Brasil (Crisafulli et al, 2016(Crisafulli et al, , 2018. La mayor diferencia es el número de punteaduras en los campos de cruzamiento que varía de 1 a 5 en el ejemplar analizado y de 1 a 3 en el holotipo.…”

“…No obstante, este rasgo y la combinación de las punteaduras en las paredes de las traqueidas justifican la asignación a Megaporoxylon, que posee punteaduras araucarioides uniseriadas, raramente biseriadas y campos de cruzamiento con punteaduras simples, ovales y en dos hileras, que son los rasgos de la especie M. kaokense Kräusel (1956). Este taxón ha sido hallado en los sedimentos del Permo-Triásico de Namibia, África (Kräusel, 1956), en la Formación Alan Nunatak, Antártica (Maheshwari, 1972) y en el Triásico de la Formación Caturrita, Brasil (Crisafulli et al 2016(Crisafulli et al , 2018. Descripción.…”