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Rio Grande, Brazil

Lopes R.P.,Institute Oceanografia
Revista Brasileira de Paleontologia | Year: 2011

Quaternary sediments along the southernmost portion of the Brazilian coast are rich in fossil remains of various terrestrial and marine organisms. This paper presents a description of fossil irregular clypeasteroid echinoids found in this area, with observations on their taphonomy. The identified taxa are Encope emarginata (Leske) and Mellita quinquiesperforata (Leske), although the latter is very scarce. All fossils consist of fragments of the test, broken along the ambulacral or interambulacral sutures. The majority of the remains consist of abraded fragments; petaloids are found either intact or collapsed. Many fossils are represented by internal molds formed by the infilling of the organisms' internal cavities by dark muddy matrix. The distribution of the fossils match the pattern observed on recent echinoid remains found along the coast. The relative absence of fossil and recent material of M. quinquiesperforata seems to be a result of taphonomic factors related to environmental processes. © 2011 by the Sociedade Brasileira de Paleontologia. Source

de Moura Queiros A.,Bangor University | Hiddink J.G.,Bangor University | Johnson G.,Bangor University | Cabral H.N.,Institute Oceanografia | Kaiser M.J.,Bangor University
Biological Invasions | Year: 2011

Introduced ecosystem engineers can severely modify the functioning on invaded systems. Species-level effects on ecosystem functioning (EF) are context dependent, but the effects of introduced ecosystem engineers are frequently assessed through single-location studies. The present work aimed to identify sources of context-dependence that can regulate the impacts of invasive ecosystem engineers on ecosystem functioning. As model systems, four locations where the bivalve Ruditapes philippinarum (Adams and Reeve) has been introduced were investigated, providing variability in habitat characteristics and community composition. As a measure of ecosystem engineering, the relative contribution of this species to community bioturbation potential was quantified at each site. The relevance of bioturbation to the local establishment of the mixing depth of marine sediments (used as a proxy for EF) was quantified in order to determine the potential for impact of the introduced species at each site. We found that R. philippinarum is one of the most important bioturbators within analysed communities, but the relative importance of this contribution at the community level depended on local species composition. The net contribution of bioturbation to the establishment of sediment mixing depths varied across sites depending on the presence of structuring vegetation, sediment granulometry and compaction. The effects of vegetation on sediment mixing were previously unreported. These findings indicate that the species composition of invaded communities, and the habitat characteristics of invaded systems, are important modulators of the impacts of introduced species on ecosystem functioning. A framework that encompasses these aspects for the prediction of the functional impacts of invasive ecosystem engineers is suggested, supporting a multi-site approach to invasive ecology studies concerned with ecosystem functioning. © 2011 Springer Science+Business Media B.V. Source

Cunha H.A.,State University of Rio de Janeiro | Cunha H.A.,Federal University of Rio de Janeiro | De Castro R.L.,CONICET | Secchi E.R.,Institute Oceanografia | And 5 more authors.
PLoS ONE | Year: 2015

The taxonomy of common dolphins (Delphinus sp.) has always been controversial, with over twenty described species since the original description of the type species of the genus (Delphinus delphis Linnaeus, 1758). Two species and four subspecies are currently accepted, but recent molecular data have challenged this view. In this study we investigated the molecular taxonomy of common dolphins through analyses of cytochrome b sequences of 297 individuals from most of their distribution. We included 37 novel sequences from the Southwestern Atlantic Ocean, a region where the short- and long-beaked morphotypes occur in sympatry, but which had not been well sampled before. Skulls of individuals from the Southwestern Atlantic were measured to test the validity of the rostral index as a diagnostic character and confirmed the presence of the two morphotypes in our genetic sample. Our genetic results show that all common dolphins in the Atlantic Ocean belong to a single species, Delphinus delphis. According to genetic data, the species Delphinus capensis is invalid. Long-beaked common dolphins from the Northeastern Pacific Ocean may constitute a different species. Our conclusions prompt the need for revision of currently accepted common dolphin species and subspecies and of Delphinus delphis distribution. © 2015 Cunha et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source

Pereira J.C.,Museu Coronel Tancredo Fernandes de Mello | Lopes R.P.,Institute Oceanografia | Kerber L.,Museu de Ciencias Naturais
Revista Brasileira de Paleontologia | Year: 2012

The Chuí Creek, located in the southernmost Brazil, is a fossiliferous outcrop known since the late 1960s, which bears important records of late Pleistocene mammals, other vertebrates and invertebrate fossils. The presence of some taxa (e.g. Hydrochoerus hydrochaeris Linnaeus, Tapirus terrestris Linnaeus, Ozotoceros bezoarticus Linneaus), although mentioned on the literature, is still to be confirmed. Specimens from Chuí Creek belonging to several collections are reexamined and new excavations and geological surveys in the area are being conducted. The new records include isolated teeth of cf. Ursidae and Rodentia (Myocastor cf. M. coypus Molina); a complete and articulated skull and jaw of a tayassuid, Catagonus Ameghino, as well as a left dentary of a juvenile ground sloth, Eremotherium cf. E. laurillardi Lund. The ongoing systematic revision led to the confirmation of the presence of the glyptodont Doedicurus Burmeister, represented by a portion of the carapace; the cervid genera Antifer Ameghino and Morenelaphus Carette; and the equids Equus Linnaeus and Hippidion Owen, represented by cranial and dental remains. These findings expand the knowledge on the diversity of the extinct fauna found in the Chuí Creek, and have biogeographic, biostratigraphic and paleoenvironmental implications, which are herein discussed. © 2012 by the Sociedade Brasileira de Paleontologia. Source

Lopes R.P.,Institute Oceanografia | Simone L.R.L.,University of Sao Paulo
Revista Brasileira de Paleontologia | Year: 2012

Fossils of the gastropods Diodora patagonica, Zidona dufresnei, Olivancillaria carcellesi, Lamniconus lemniscatus carcellesi and the bivalve Arcinella brasiliana are registered for the first time from the outcrops of Chuí Creek, on the coastal plain of Rio Grande do Sul State, southernmost Brazil, together with other taxa previously known elsewhere. The specimens were collected in a shallow Pleistocene marine facies exposed at the base of the banks of the creek, in a fossil concentration possibly formed by storm events. The taxa described here live in shallow environments (with the exception of A. brasiliana and Z. dufresnei) with sandy bottoms (except for D. patagonica, T. patagonica, B. odites, C. rhizophorae and A. brasiliana). The presence of L. lemniscatus carcellesi, found living today only in Uruguay and Argentina, indicates a wider distribution for this taxon during the late Pleistocene. © 2012 by the Sociedade Brasileira de Paleontologia. Source

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