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| Wesselingh, F.P.; Ranzi, A.; Räsänen, M.E.. |
| Thirteen species of fossil molluscs are reported from the Solimões Formation of western Brazilian Amazonia. Based on mammalian chronology of the Solimões Formation and radiometric ages reported from coeval deposits in adjacent Peru, the age of the fauna is established as Late Miocene. The fauna includes five prosobranch gastropod species, seven pearly freshwater mussel species and one sphaeriid bivalve species. The supposed presence of Pachydon (Corbulidae: Bivalvia) in these deposits is rejected; Pachydon acreanum, whose status has long been uncertain, is transferred to the unionoid genus Callonaia. The Solimões mollusc fauna is entirely composed of obligate freshwater taxa, resembling species-poor modern Amazonian fluvial faunas. The presence of the... |
| Tipo: Article / Letter to the editor |
Palavras-chave: Mollusca; Western Amazonia; Miocene; Solimões Formation.; 38.22; 42.73. |
| Ano: 2006 |
URL: http://www.repository.naturalis.nl/record/209736 |
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| Wesselingh, F.P.; Anderson, L.C.; Kadolsky, D.. |
| The mollusc fauna of the Miocene Pebas Formation of Peruvian and Colombian Amazonia contains at least 158 mollusc species, 73 of which are introduced as new; 13 are described in open nomenclature. Four genera are introduced (the cochliopid genera Feliconcha and Glabertryonia, and the corbulid genera Pachyrotunda and Concentricavalva) and a nomen novum is introduced for one genus (Longosoma). A neotype is designated for Liosoma glabra Conrad, 1874a. The Pebas fauna is taxonomically dominated by two families, viz. the Cochliopidae (86 species; 54%) and Corbulidae (23 species; 15%). The fauna can be characterised as aquatic (155 species; 98%), endemic (114 species; 72%) and extinct (only four species are extant). Many of the families represented by a few... |
| Tipo: Article / Letter to the editor |
Palavras-chave: Mollusca; Systematics; Pebas Formation; Miocene; Western Amazonia; 42.73; 38.22. |
| Ano: 2006 |
URL: http://www.repository.naturalis.nl/record/209728 |
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| Bernini,Thiago Andrade; Pereira,Marcos Gervasio; Anjos,Lúcia Helena Cunha dos; Perez,Daniel Vidal; Fontana,Ademir; Calderano,Sebastião Barreiros; Wadt,Paulo Guilherme Salvador. |
| The variety of soils in the State of Acre is wide and their chemical profiles are still not fully understood. The nature of the material of origin of these soils is indicated by the high aluminium (Al) content, commonly associated with high calcium (Ca) and magnesium (Mg) contents. The study objective was to use different methods to quantify Al in soils from toposequences formed from material of a sedimentary nature originating from the Solimões Formation, in Acre, Brazil. Trenches were opened at three distinct points in the landscape: shoulder, backslope and footslope positions. Soil samples were collected for physical, chemical, mineralogical analyses. The Al content was quantified using different methods. High Al contents were found in most of these... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Exchangeable aluminium; Sedimentary material; Smectite; Western Amazonia. |
| Ano: 2013 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832013000600015 |
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