Gaea - Journal of Geoscience

Acta Geologica Leopoldensia (1976-2004) e Gaea – Journal of Geoscience (2005-2016): contribuição à evolução do conhecimento geológico do Brasil e da América do Sul

2016-06-17T09:54:15-03:00

Pollen diversity in cerrado’s fitophisionomies in central Brazil and palaeoenvironmental implications

2016-06-17T09:54:15-03:00

The Cerrado is one of the most biodiverse biomes of Brazil and contains a great diversity of fitophysionomies. Over the past millennia, the vegetation of theCerrado has been modified and influenced greatly by the climate changes and other factors, shaping the diversity exhibited today. Palynological studies of Quaternary sediments of the Cerrado’s region is an important source of information about these changes and about the history of this type of vegetation. The interpretation of this palinological records is improved by the characterization of modern pollen spectra and determination of the relationship between them and modern vegetation. With this purpose, this catalog presents the results of the analysis of surface samples collected in three national parks, where the native vegetation of the Cerrado is preserved. Sixty pollen types are described and information about their occurrence and abundance in the different environments of the Cerrado is given. Additionally, pollen taxa that can be considered paleo-indicators of certain fitophysionomies are determined.

Keywords: Cerrado, pollen morphology, fitophysionomies.

Natural associations of Mesogondolella spp. conodonts, Itararé Group, Cisuralian of Paraná Basin

2016-06-17T09:54:15-03:00

Conodonts are primitive chordates which lived during the Paleozoic up to their complete extinction at the Triassic. Exclusively marine, they are widely used in biostratigraphic studies and in studies about vertebrates’ evolution, nowadays, in a new bias, with the discoveries of natural associations of multi-element that helps to better understand the evolutionary mechanisms of the first vertebrates and the paleobiology of this group. Researchers from the Earth and Life Museum of the Paleontological Center in the Contestado University (CENPALEO) found tens of ramiform elements near Mafra, southern Brazil, which macroscopically were similar with porifera spicule, common in the outcrops of the region. After a more detailed analysis, these elements were identified as conodonts feeding apparatuses, in general complete and well-preserved. This article describes the feeding apparatuses of conodonts of the first occurrence of conodonts in the Paraná Basin. They represent gondolelids conodonts belonging to the Mesogondolella genus, a well-known Cisuralian marker. It is also discussed the faunas of these primitive chordate, according to the natural associations found in the Lontras Shale, Itararé Group, Paraná Basin.

Keywords: Mesogondolella, Cisuralian, Lontras Shale, Permocarboniferous.

In-situ Late Triassic fossil conifer woods from the fluvial channel deposits of the Soturno River (Caturrita Formation, Rio Grande do Sul, Brazil)

2016-06-17T09:54:15-03:00

Three new fossil gymnosperm woods are described from a new outcrop exposed on the margins of the Soturno River, State of Rio Grande do Sul, eastward located in relation to other well-known petrified forests from São Pedro do Sul and Mata, in South Brazil. The interest of their study lays on the in situ condition of the woods and its inclusion in the fluvial deposits of the Caturrita Formation, at Faxinal do Soturno County, from where such kind of fossil material were known only recently. The analysis allows to assign it to the conifers Agathoxylon africanum (Bamford) Kurzawe and Merlotti, Megaporoxylon kaokense Kräusel and Chapmanoxylon sp. cf. C. jamuriense Pant and Singh. Previously known mainly from Permian localities of Gondwana (Namibia, India and South America), and with few Triassic representatives, the field relations and stratigraphic context suggest a Late Triassic age and a life around low sinuosity river systems under the influence of climatic seasonal dry conditions.

Keywords: fossil woods, Agathoxylon, Megaporoxylon, Chapmanoxylon, Late Triassic, Brazil.

The use of MS ACCESS for database in the management of collections: A case study in Paleontological museums

2016-06-17T09:54:15-03:00

A new approach incataloguing fossil samples stored in scientific collection is herein presented. By the use of a Databases and their management, a query mode inpaleontological collections is applied using the Microsoft Office ACCESS tool. With this purpose, two Brazilian paleontological collection were usedto verify the internal management and facilities of this application, the Paleoinvertebrates repository from the National Museum of Rio de Janeiro(MN), at UFRJ (Federal University of Rio de Janeiro), and the Paleobotany and Paleoinvertebrate collections from LaViGæa/MHGEO Museum, atUnisinos (Vale do Rio dos Sinos University). The databases were developed using previous enters furnished by the Catalogue books (e.g. sourcelocality and taxonomy) and in accord with its page disposition – a table form. It takes into account that in a Database, a table is a basic componentand represents a group of data. Fifteen tables were constructed, with the main ones (“Tbl Paleoinvertebrados” or “Tbl Paleobotânica”) and therelated secondaries, whose data are stored in the principal one. Therefore, 34 (MN) and 33 (LaViGæa, Unisinos) fields were constructed, with acapacity of storage of more than 900,000 samples. The data is inserted through the form “Frm_ Paleoinvertebrados” or “Frm_ Paleobotânica”, since all of the fields are easily viewed, which minimizes the mistakes. The Databases constructed, using the ACCESS, demonstrate its easy performanceand agility in data insertion. The use of a Tab key allows to access the fields, and a “Combo Box” in the majority of the fields (32) allowsto automatically save the data with a click in the specific name. The system is able to print labels, attach photos and has “a query mode”, allimportant resources in doing any research faster and useful. The good resolution and innovation of this project was mainly due to the partnershipbetween researchers and the programmer.

Keywords: MS ACCESS, Database, Fossil collections management, query mode.

Taphonomic aspects and the Lilliput Effect on Devonian discinoids of the Paraná Basin, Apucarana Sub-basin, Brazil

2016-06-17T09:54:15-03:00

Discinoids are exclusively marine, epibenthic, inarticulate brachiopods, which use their pedicle to attach to the substrate. The global stratigraphic range of the genera range from the ?Ordovician to Holocene, but the Devonian period was the climax of this group. They have a broad geographical distribution and, in Brazil, are found in the Paraná, Amazonas, Parnaíba and Parecis basins. The discinoids from the Paraná Basin are found in the Ponta Grossa and São Domingos formations. Three genera of discinoids are recorded in the Brazilian Devonian strata, Orbiculoidea, Gigadiscina and Rugadiscina. Five species are recognized in the Paraná basin (Orbiculoidea baini, Orbiculoidea bodenbenderi, Orbiculoidea excentrica, Gigadiscina collis and Rugadiscina sp.). As far the taphonomy is concerned, the discinoids can be found isolated or in clusters, as complete and articulated valves, or as complete and disarticulated valves and/or fragmented valves, and constitute assemblages of shoreface and offshore settings. The analysis presented herein establishes the stratigraphic range of the Discinidae family between the late Pragian and the early Givetian. Orbiculoidea baini and Orbiculoidea excentrica showed phenotypes with reduced size attributed to the Lilliput Effect. This effect resulted of a biotic crisis recorded shortly before the collapse of Malvinokaffric fauna that caused a global extinction, the Ka?ák Event, in the Eifelian-Givetian transition.

Keywords: Discinoids, Lilliput Effect, Devonian, Ka?ák Event, Taphonomy.