Vladimir de Araújo Távora

New species of Hippopleurifera (Bryozoa, Cheilostomata) from the Miocene Pirabas Formation, Pará state, Brazil

The Pirabas Formation in Brazil has been studied for many years and a great diversity of animal groups (in particular fishes, molluscs and echinoderms) have been described from there, whereas the Bryozoa have scarcely been mentioned. New samples, collected specifically to focus on bryozoans, have shown that the diversity in this formation is higher than previously thought. Here we describe two new species belonging to the cheilostomate genus Hippopleurifera--H. barbosae sp. nov. and H. confusa sp. nov. Both species were collected at Atalaia Beach, northeastern Pará state, which boasts some of the best marine Cenozoic fossil outcrops in Brazil. After accounting for all described species, plus the two new species and four generic reassignments (new combinations) described herein, some 29 Hippopleurifera species are now known. Most of these are fossils from Europe or the USA, but a handful are known from the Recent Mediterranean, Caribbean and Indo-West Pacific.

New records of the Bryozoan Metrarabdotos from the Pirabas Formation (Lower Miocene), Pará State, Brazil

The Pirabas Formation in Pará State, Brazil, contains a very rich and diverse fauna of Early Miocene age, including several groups of invertebrates and vertebrates. Previous studies of bryozoans from Brazil included two species of Metrarabdotos ones, but these need revision. The present study describes three new species of Metrarabdotos (M. aquaeguttum sp. nov., M. elongatum sp. nov., M. capanemensis sp. nov.) collected from two outcrops: Atalaia Beach at Salinópolis city and B-17 Mine at Capanema city. Laís V. Ramalho. Instituto Español de Oceanografia – IEO, Puerto Pesquero, s/n, Fuengirola. 29640; and Universidad de Málaga, Málaga – España. laiscanabarro@yahoo.com.br Vladimir A. Távora. Laboratório de Paleontologia, Faculdade de Geologia, Instituto de Geociências, Universidade Federal do Pará, Caixa Postal 1611, Belém, Pará, Brazil. vladimir@ufpa.br Kamil Zagorsek. Department of Geography, Technical University of Liberec, Studentská 2, CZ-461 17 Liberec, Czech Republic. kamil.zagorsek@gmail.cz

Considerações Paleobiogeográficas dos Corais e Briozoários do Devoniano Brasileiro

Os corais e briozoarios devonianos brasileiros estao registrados nas bacias do Amazonas e Parana, respectivamente nas formacoes Maecuru e Ponta Grossa. Na regiao amazonica sao duas especies de corais e oito de briozoarios, enquanto na regiao sul e sudeste a ocorrencia de ambos os grupos esta limitada a citacoes gerais. A baixa diversidade especifica e o pequeno tamanho das populacoes relacionam-se com limitacoes ecologicas, filogeneticas e preservacionais, alem do numero insuficiente de pesquisas especificas.

Paleoinvertebrados e Paleoambientes da Formação Pirabas (Mioceno inferior) em Aricuru, Município de Maracanã, Estado do Pará, Brasil

This work consists of a systematic study of fossil macroinvertebrates collected from Pirabas Formation, at Aricuru locality, northeast of Para State. Were recognized 25 species including macroforaminifera, corals, macrobryozoans, bivalves and gastropods mollusks, decapod crustaceans and echinoids. Ichnofossils related to Thalassinoides , produced by decapoda crustacean and peracarids also occurs in the outcrop. The stratigraphic framework, environmental requirements and preservational features of paleoinvertebrate species of Aricuru outcrop allowed to assume that the fluctuations of bathymetry and salinity have not been very significant, but influenced the living species in the ecospace. These data suggest that the lagoon at Aricuru is its distal segment characterized by minor influence of the depositional hydrodinamic and the longer duration in the sea level fluctuations, occupied by a specialized fauna.

Revisão Sistemática da Família Flabellidae (Scleractinia) da Formação Pirabas (Mioceno inferior), Estado do Pará, Brasil

This research deals the systematic review of the corals belonging to the Flabellidae family, assigned to subgenus Flabellum (Flabellum). Were confirmed F. (F.) lyricum Fernandes, 1981 and F. (F.) wailesi Conrad, 1855, as well as the first record of the F. (F.) dens Alcock, 1902 and F. (F.) chipolanum Weisbord, 1971 from the Pirabas Formation. The lithological and preservational settings suggest that these corals lived only in the marine environment and therefore are allochtonnous in the biocalcirudites that occur at B-17 Mine, considered the largest areal extent of the paleolagoon of the Pirabas/Barreiras sequence.

Micropaleontologia da Litofácies Recifal da Formação Pirabas (Mioceno inferior), Estado do Pará, Brasil

This work presents the resulting data from microfossils analysis of the Pirabas Formation reef lithofacies, exposed in the Macarico beach, Salinopolis city, Para State, Brazil. The specific diversity and abundance indicates reef environment developed in warm and shallow waters with high energy and high availability of calcium carbonate. The microfossils also suggest low to moderate sedimentation rate and variable substrate composition. The intense diagenesis appears to have dissolved many specimens but the strucuture of the primary orictocoenosis was preserved.

Geologia e paleontologia do biohermito da Formação Pirabas (Mioceno Inferior)

This work concerns with the detailed geological and paleontological study of the reef facies of the Pirabas Formation, that outcrop at the Macarico beach, of Salinopolis district, Para State, as a small, isolated and lenticular sedimentary bodie developed in the inner platform inner ramp of the Pirabas Sea. The biotic constituents are diverse and composed by three groups of coralline algae, sponges, corals, bryozoans, echinoids, foraminifera, ostracodes and molluscs. Three stages of the ecologic sucession were recognized in this patch reef: stabilization, colonization and diversification. Thin micritic crusts, recognized at top of the beds in diversification stage suggest the degradation of the environmental conditions favorable to reef accretion probably due to continentalization of the depositional site. The petrographic investigation reveals only one, homogeneous depositional microfacies, named biomicrite, without compositional and textural changes. The marine cementation is represented by microcrystalline agglomerates and micritic cement, locally neomorphosed to biosparite and detrital carbonatic components of the unconsolidated biogenic debris, resulted from the disintegration of the aragonite from the algalic remains accumulated as micritic mud. In the construction of the reef framework the red macroalgae were fundamental to the lithification and building of the framework, and very important to the protection and cementation of the others constituents.