Impressões foliares pleistocenas de Malvaceae na área de abrangência do Aproveitamento Hidroelétrico Jirau, Rondônia, Brasil

This paper aims to describe the morphology and taxonomic identification of ten angiosperm leaf impressions collected in Rio Madeira Formation outcrop in the area from Jirau Hydroeletric Dam, found by the team of Paleontological Research, Monitoring and Rescue Program. Due to the preservation and based on morphology, the specimens were identified at the genus level. All specimens belong to the family Malvaceae, and nine specimens were identified as Luehea and one specimen belongs to the genus Theobroma. Two samples were taken from the layer below to the fossiliferous bed, in order to carry dating by method “Accelerator Mass Spectrometry” (AMS C14). The dating pointed ages between 15.910 and 14.850 years calibrated BP. The genus reported here are common in current forest cover in the region of AHE Jirau, and their presences are also confirmed by palynological data obtained for the upper part of the Rio Madeira Formation.Este trabalho tem como objetivo descrever a morfologia foliar e realizar o reconhecimento taxonô- mico de dez impressões foliares de angiospermas coletadas em afloramento da Formação Rio Madeira na área de abrangência do Aproveitamento Hidrelétrico (AHE) Jirau, resgatadas pela equipe do Programa de Investiga- ção, Salvamento e Monitoramento Paleontológico. Devido à preservação e com base na descrição morfológica, os espécimes foram identificados até o nível de gênero. Todos os espécimes mostram caracteres que indicam sua relação com a família Malvaceae, nove deles com o gênero Luehea e um exemplar ao gênero Theobroma. Duas amostras foram retiradas da camada inferior àquela que concentra os fósseis, com o objetivo de realizar datação através do método “Accelerator Mass Spectrometry” (AMS C14). A datação apontou idades entre 15.910 e 14.850 anos calibrados AP. Os dois gêneros registrados são comuns na cobertura florestal atual na região do AHE Jirau, e a sua presença é também confirmada pelos dados palinológicos obtidos para a parte superior da Formação Rio Madeira

Itaquixylon heterogenum BENICIO, PIRES, DA ROSA, SPIEKERMANN, UHL et JASPER 2016, sp. nov.

Itaquixylon heterogenum BENICIO, PIRES, DA ROSA, SPIEKERMANN, UHL et JASPER sp. nov. H o l o t y p e. UFSM 12032 (Repository: Coleção Paleontológica da Universidade Federal de Santa Maria, Rio Grande do Sul, Brazil). E t y m o l o g y. The specific name, heterogenum, is due to the presence of heterocellular rays. T y p e h o r i z o n. Touro Passo Formation. A g e. Late Pleistocene, 14,600 years (TL). T y p e l o c a l i t y. (29º23'55.9"S / 56º42'05.9"W), Itaqui city, Rio Grande do Sul State, Brazil. D i a g n o s i s. Angiosperm wood, diffuse porosity, numerous vessels in tangential bands; vessels generally solitary, sometimes in radial multiples of 3 to 5, circular to oval in outline, with narrow diameter and short length, helical thickenings absent, tyloses present; simple perforation plates; alternate intervessel pits, vestured, circular, small with lenticular irregular aperture slightly oblique; vessel-ray pits and vessel-parenchyma pits bordered; libriform fibres, non-septate, extremely short and narrow, with simple minute pits; paratracheal axial parenchyma, vasicentric and scanty and apotracheal axial parenchyma diffuse; rays are nume. rous, exclusively heterocellular, composed of procumbent and square marginal cells, short and extremely narrow, simple pits of minute size; mostly uniseriate, less frequently biseriate and triseriate, rarely tetraseriate; aggregate rays are absent. D e s c r i p t i o n. Distinctive growth rings, alternately separated by light and dark bands (Pl. 1, Fig. 1), marked by radially flattened thick-walled latewood fibres versus thin-walled earlywood fibers. Absence of stratification in secondary xylem elements. Wood diffuse-porous (Pl. 1, Figs 1–2). Vessels in tangential bands (Pl. 1, Figs 1–2), numerous (16–36/mm²), occupying 25.6% of the cross section (Pl. 1, Figs 1–2). Vessels generally solitary, sometimes in radial multiples of 3 to 5, circular to oval in outline (Pl. 1, Figs 2–3). Mean tangential diameter 65.5 (32–96) µm, mean length 186.5 (48–360) µm. Helical thickenings in vessel elements are absent. Simple perforation plates (Pl. 2, Fig. 4), intervessel pits alternate, small 4.1 (2–8) µm, vestured, with lenticular irregular slightly oblique apertures (Pl. 1, Figs 4–5). Vessel-ray pits with distinct borders, rounded and bordered (Pl. 1, Figs 4–5). Vessel-parenchyma pits are similar to vessel-ray pits. Tyloses (Pl. 1, Figs 2–6) and prismatic crystals are present in the marginal square ray cells (Pl. 2, Figs 4–6). Fibres libriform, non-septate, with simple and minutely bordered pits 2.3 (1–4) µm (Pl. 2, Figs 1–4), occupying 45% of the wood. The fibres are extremely short, mean length 162 (30–360) µm, narrow 3.2 (1–8) µm and thin-walled 1.9 (1–4) µm, with a narrow diameter of 3.9 (2–8) µm. The paratracheal axial parenchyma is vasicentric and scanty, occupying only 5.45% of total wood volume (Pl. 1, Figs 2–3). The apotracheal axial parenchyma is diffuse, with dispersed cells between the fibers (Pl. 1, Fig. 2–3). Axial parenchyma cells are rectangular (Pl. 2, Fig. 2), mean length 36.9 (16–80) µm and mean width 18.5 (8–32) µm, constituting a series with mean length 364.8 (176–896) µm, composed of 13 (3–6) cells. Rays are numerous, occupying 24% of the volume of the wood (Pl. 1, Figs 1–2). They are mostly uniseriate (44%), less frequent biseriate (27%), triseriate (21%) and tetraseriate (8%) (Pl. 2, Figs 1–3). Aggregate rays are absent. Rays are heterocellular, composed of procumbent cells and 1–4 rows of square marginal cells, most commonly 2 rows (Pl. 2, Figs 4–5). Uniseriate rays extremely short, mean length 204.9 (112–424) µm, and extremely narrow, mean width 12.4 (8–24) µm, 7 to 27 cells high (Pl. 2, Figs 1–3). The multiseriate rays are narrow, mean width 26.8 (16–40) µm, 1 to 4 cells wide, and very short, mean length 241.5 (120–556) µm, 8 to 27 cells high (Pl. 2, Figs 1–3). In tangential section, the ray cells are circular to oval (Pl. 2, Figs 1–3) with minute simple pits, ranging from 1 to 4 µm.Published as part of Benicio, Jose R. W., Pires, Etiene F., Da Rosa, Átila A. S., Spiekermann, Rafael, Uhl, Dieter & Jasper, André, 2016, A New Fossil Fabaceae Wood From The Pleistocene Touro Passo Formation Of Rio Grande Do Sul, Brazil, pp. 251-264 in Fossil Imprint 72 (3 - 4) on page 254, DOI: 10.14446/FI.2016.251, http://zenodo.org/record/538790

Relation between the sedimentary organic record and the climatic oscilations in the Holocene attested by palynofacies and organic geochemical analyses from a pond of altitude in southern Brazil

This paper presents the quantitative and qualitative results obtained from palynofacies and geochemistry analyses carried out on a core covering approximately 8000 years of sedimentation of a pond of altitude located at the mining district of Ametista do Sul, southernmost Brazil. The main objective of this paper is to consider the paleoclimatic and paleoenvironmental significance of these analyses. The hydrological isolation renders this pond climatically sensitive to variations in pluviometric regime and this enabled infer rainfall events during the early Holocene, which was responsible for the beginning of the processes of water accumulation in the gossan and the sedimentation of the pond. Changes in the pattern of moisture over the time become the drier environment, resulting in the intermittent pattern of water depth that currently exists at the site. The fluctuations in water depth are inferred from the frequency of Botryococcus and other algae, which tend to decrease progressively toward the top where the autochthonous elements are replaced by parautochthonous and allochthonous elements. Pseudoschizaea, in turn, appears to act as a biological marker of these transitional intervals. The present results are of great importance for understanding the extent of climate change and its environmental impacts at regional and global levels

Sommerxylon spiralosus from Upper Triassic in southernmost Paraná Basin (Brazil): a new taxon with taxacean affinity

The anatoical description of silici?ed Gymnospermae woods from Upper Triassic sequences of southernmost Paraná Basin (Brazil) has allowed the identi?cation of a new taxon: Sommerxylon spiralosus n.gen. et n.sp. Diagnostic parameters, such as heterocellular medulla composed of parenchymatous and sclerenchymatous cells, primary xylem endarch, secondary xylem with dominant uniseriate bordered pits, spiral thickenings in the radial walls of tracheids, medullar rays homocellular, absence of resiniferous canals and axial parenchyma, indicate its relationship with the family Taxaceae, reporting on the first recognition of this group in the Triassic on Southern Pangea. This evidence supports the hypothesis that the Taxaceae at the Mesozoic were not con?ned to the Northern Hemisphere.<br>A descrição anatômica de lenhos silicificados de Gymnospermae em seqüência do Triássico Superior no sul da Bacia do Paraná (Brasil), possibilitou a identificação de um novo taxon: Sommerxylon spiralosus n.gen. et n.sp. Parâmetros diagnósticos tais como medula heterocelular, composta por células parenquimáticas e esclerenquimáticas, xilema primário endarco, xilema secundário com pontoações areoladas unisseriadas dominantes, espessamentos espiralados nas paredes radiais dos traqueídeos, raios lenhosos homocelulares, ausência de canais resiníferos e de parênquima axial, indicam a sua vinculação à família Taxaceae, constituindo-se em reconhecimento inédito da presença deste grupo no Triássico Superior no sul do Pangea. Esta evidência suporta a hipótese de que a família Taxaceae não estava confinada ao Hemisfério Norte durante o Mesozóico