The Triassic Taphoflora From Parana Basin, Southern Brazil: An Overview

Abstract

A Triassic Dicroidium Flora identified in the central region of the State of Rio Grande do Sul, Southern Brazil, represents an important biostratigraphic stage in the palaeofloristic succession of Parana basin. The megafloristic association composed of compressed leaves, fronds and seeds shows a predominance of the genus Dicroidium, with several species, and other important taxa like Neocalamites sp, Cladophlebis sp., Tetraptilon aff. heteromerum, Ginkgoites antarctica, Sphenobaiera sp, Podozamites sp, Nilssonia sp, Pteruchus sp and Carpolithus sp. Taking into account the stratigraphic distribution of different species of the genus Dicroidium, a biostratigraphic framework was previously established and an informal floristic interval, named "Dicroidium odontopteroides Flora" was proposed (Late Anisian to Late Ladinian, Middle Triassic). The general composition of the Dicroidium Flora in Rio Grande do Sul is similar to the "Dicroidietum odontopteroidium" characterized for Australasia corresponding to a forest association composed by trees, woody shrubs, ground cover and swamps growths. The presence of xilopteroid leaves indicates levels of water stressed substrate. The homogeneous composition of the assemblage, and the small size of leaves of the whole association in relation to the Dicroidium Flora of other Gondwana regions (e. g. Molteno Formation) seems to indicate particular drainage patterns prevailing during deposition of Santa Maria Formation.

First record of Ginkgo-related fertile organs (Hamshawvia, Stachyopitys) and leaves (Baiera, Sphenobaiera) in the Triassic of Brazil, Santa Maria formation

“…The oldest examples, from the Lower Permian Itararé Group and Rio Bonito Formation, include incomplete leaves of Ginkgoites eximia Seward, Ginkgophytopsis Høeg, Dicranophyllum and Cheirophyllum speculare Césari and Cúneo, the latter exhibiting dubious affinities to the Ginkgoales (Silva and Iannuzzi, 2000). They were associated with assemblages composed mostly by pteridosperms (Glossopteris and Gangamopteris), accompanied by sphenopsids and primitive conifers (Guerra-Sommer et al, 1999;Guerra-Sommer and Klepzig, 2000).…”

Mummified Dicroidium (Umkomasiales) leaves and reproductive organs from the Upper Triassic of South Australia

“…The genus becomes a common element of fossil assemblages in Spathian strata (RETALLACK 1977;HOLMES & ASH 1979) and dominates floras in succeeding strata up to theend-Triassic extinction horizon (BALME et al 1995). Dicroidium has its centre of distribution in the middle and high palaeolatitudes of Gondwana, with particularly large collections described from the Middle to Upper Triassic of South Africa (DU TOIT 1927;THOMAS 1933;ANDERSON & ANDERSON 1983), South America (FRENGUELLI 1943(FRENGUELLI , 1944bBORTOLUZZI & BARBERENA 1967;ARCHANGELSKY 1968;PETRIELLA 1981;GUERRA-SOMMER & CAZZULO KLEPZIG 2000), Antarctica (TOWNROW 1967;BOUCHER et al 1993;BOMFLEUR & KERP 2010;ESCAPA et al 2011;BOMFLEUR et al 2012), India (e.g., FEISTMANTEL 1879aPAL et al 2014;RAO & LELE 1962;SEWARD 1932), Australia (e.g., WALKOM 1917, 1925a, 1928JONES & DE JERSEY 1947;TOWNROW 1957;HOLMES & ANDERSON 2005;PATTEMORE 2016), and New Zealand (e.g., ARBER 1913RETALLACK 1980b).…”

Geochemical study of the vertebrate assemblage zones of the Santa Maria Supersequence (Middle to Late Triassic), Paraná Basin, Brazil

“…Horn et al (2018b) identified some climatic changes between the SMS biozones, from driest to wetter, in particular between the lowermost (Dinodontosaurus and Santacruzodon) and the uppermost (Hyperodapedon and Riograndia). Guerra-Sommer and Klepzig (2000) and Barboni and Dutra (2015) reported occurrences of leaves, Cuticule fragments and ex situ fossil woods, with a predominance of the genus Dicroidium, in the Middle-Upper Triassic package (Passo das Tropas Member) paleoflora. This genus includes the Division Ginkgophyta.…”