Netto, R.G., Carmona, N.B. & Tognoli, F.M.W. (Eds.). 2012. Ichnology of Latin America – selected papers. Porto Alegre: Sociedade Brasileira de Paleontologia, Monografias da Sociedade Brasileira de Palentologia, 196 p.
The Coastal Plain of Rio Grande do Sul state (CPRS), in southern Brazil, is known for the presenc... more The Coastal Plain of Rio Grande do Sul state (CPRS), in southern Brazil, is known for the presence of fossil accumulations containing remains of both marine and terrestrial Pleistocene organisms, in large biodetrital concentrations on the continental shelf and also in continental outcrops in Chuí Creek and Mangueira Lake. Many invertebrate remains exhibit bioerosion traces caused by endoskeletozoan organisms, while surface colonization by episkeletozoans is scarce. The ichno-traces Entobia and Caulostrepsis are the most common, followed by Pennatichnus, Gastrochaenolites and Maeandropolydora. Gastrochaenolites is found mostly in ostreids and Oichnus is mostly absent among fossils from the continental shelf and Passo da Lagoa, but is found in many bivalves from Chuí Creek. Ichno-traces identified as cf. Clionoides isp. are recorded for the first time among fossils from CPRS. Bioincrustation on invertebrates is very scarce, represented by cheilostomate bryozoans, ostreids and cirripeds. Among vertebrate remains found in the continental shelf, bioerosion has been recorded so far on three specimens; remains collected at greater depths are mostly covered by fouling organisms, including serpulid polychaetes and corals. While bioerosion is the predominant ichnological process affecting fossils from shallower areas, bioincrustation affects mostly remains found in deeper areas of the shelf. Ichnological differences among invertebrate fossils found in the continental shelf and those from outcrops in terrestrial environment seem to be related to marine transgressions and regressions that affected the area during the Late Quaternary.
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barreiras arenosas que isolam diversos corpos lagunares no litoral norte do Estado, e uma extensa lagoa (Mangueira), com cerca de 100 km de extensão no litoral sul. Este setor da costa vem sendo submetido a processos dinâmicos costeiros desde o início do Holoceno que resultaram na formação de dunas eólicas.
Como resultado, a porção centro-sul da margem leste da lagoa Mangueira é caracterizada pela presença de extenso campo de dunas de grande beleza cênica, altura expressiva e importância ambiental. As dunas são habitat de diversas espécies de mamíferos, aves, insetos e plantas, contendo evidências arqueológicas da ocupação por paleo-índios. A praia oceânica adjacente ao campo de dunas é notável pela presença de
concheiros, que constituem extensas e espessas concentrações
fossilíferas de moluscos, crustáceos e vertebrados marinhos e mamíferos terrestres pleistocênicos, removidos de depósitos submersos e transportados para a praia pela dinâmica costeira.
Sistema Laguna-Barreira III, correspondente à penúltima
transgressão-regressão, acumularam-se fósseis de mamíferos extintos pertencentes à megafauna de idade Lujanense (cerca de 120.000 anos A.P.). Atualmente, esses depósitos são bem conhecidos em afloramentos ao longo das barrancas do arroio Chuí.. O estudo desses depósitos e fósseis tem fornecido valiosas informações a respeito dos aspectos paleoecológicos
e paleoclimáticos do sul do Brasil e melhorado nossa
compreensão dos processos físicos costeiros que levaram
à formação da planície costeira do Rio Grande do Sul.
Papers by Renato Lopes
extinction of all mammals with body mass >300 kg and several smaller taxa, but the driving mechanisms
behind it are still poorly understood. Here is presented an analysis of the extinction in the Pampa of
southern Brazil (Rio Grande do Sul state), based on fossil assemblages found in the coastal plain (CPRS)
and western area of the state (WRS). The comparison between fossil and extant mastofaunas show that
90% of the mammals represented in fossil assemblages went extinct, and allowed distinguishing three
groups: 1) taxa that underwent local extinction, i.e., disappeared locally but survived in other regions
until becoming extinct later (including all megamammals); 2) pseudoextinct taxa that disappeared
locally but survive until today in other areas, and 3) taxa that disappeared locally but returned during the
Holocene. The faunal changes recorded along stratigraphic successions and available numerical ages
indicate two phases of extinction, the first around 30 ka b2k in the CPRS (apparently also recorded in
Argentina and Uruguay) would have been related to the onset of the cold and dry conditions of the
stadial MIS 2, predating the arrival of humans to the region by about 25 kyrs. The second phase eliminated
taxa that survived until about 12.7 ka BP in WRS in reduced suitable environments (‘refugia’)
associated with perennial rivers; it coincides with the transition from glacial to interglacial conditions,
but pollen data suggest that humans may have contributed for environmental modifications through fire.
The results show that the Pleistocene xenarthran-dominated mastofauna was replaced by a Holocene
fauna dominated by small rodents and carnivores, and indicate that climate-driven environmental
changes, also influenced by sea-level oscillations, were a major agent in the Late Pleistocene mammalian
extinctions in the Brazilian Pampa.
RESUMO-O registro fóssil de aves do sul do Brasil é escasso e consiste de poucos elementos isolados. Aqui é descrito um fóssil de ciconídeo na assembleia de restos de mamíferos da Formação Santa Vitória. O espécime consiste de uma vértebra cervical morfologicamente similar a Ciconia maguari (joão-grande), comum atualmente no sul do Brasil. Entretanto, suas dimensões maiores sugerem que poderia ser um morfotipo daquela espécie ou outra espécie extinta. As modificações tafonômicas na vértebra resultam da combinação de fatores autogênicos e alogênicos incluindo o hábito aquático, forma e transporte por água corrente e soterramento em um riacho raso. O sedimento fossilífero datado por luminescência foi depositado no Neopleistoceno, há 37,9 ka, e exibe características que indicam deposição sob descarga variável e oscilações sazonais do lençol freático. A presença de uma ave aquática em sedimentos depositados por água indica um período de precipitação elevada, cronocorrelacionado a um dos pulsos quentes em escala milenial registrados em testemunhos de gelo da Antártica (Máximos Isotópicos Antárticos) que caracterizaram o interestadial MIS 3. Por outro lado, o clima frio e seco do glacial seguinte MIS 2 pode ter forçado os ciconídeos e mamíferos aquáticos a se retirarem para áreas adequadas (refúgios), como sugere sua ausência nos depósitos de loess (Formação Cordão) acima da FSV, até retornar durante o Holoceno, quando o clima se tornou úmido e quente novamente. Os resultados apresentados aqui ampliam o registro fóssil de aves do sul do Brasil e ajudam a compreender o papel das mudanças climáticas na distribuição de aves ciconídeas e outros táxons durante o Quaternário no sul da América do Sul. Palavras-chave: Ciconiidae, Formação Santa Vitória, tafonomia, MIS 3, paleoambiente, paleoclima.
estruturas são encontradas em diversos locais do sudeste e sul do Brasil, ocorrendo em diferentes tipos de substratos,
desobstruídas (paleotocas) ou preenchidas por sedimentos (crotovinas). A paleotoca encontrada no município de Cristal
(RS) foi escavada nos depósitos de leques aluviais terciários e marcas de garras e impressões da carapaça podem ser vistas
ao longo da superfície interna da galeria. As dimensões da estrutura, as marcas de escavação e marcas de osteodermos
presentes ao longo das paredes da paleotoca sugerem que tenha sido produzida por um xenartro dasipodídeo. A comparação
com estruturas similares encontradas na Argentina pode fornecer informações mais detalhadas a respeito da paleoecologia e
bioestratigrafia dos organismos responsáveis por sua escavação.
Sul State, southern Brazil. The concentrations were found at the same stratigraphic interval, some 7.5 m above present sea-level,
in a layer deposited in a shallow marine environment during the penultimate marine transgression around 230 ka BP and currently
exposed along the banks of Chuí Creek, located some 11 km landwards of the present coastline. The assemblage is composed
of a mixture of highly fragmented, unidentifi able shells and well-preserved bivalves and gastropods. Many bivalve remains are
complete, including juveniles and thin-shelled taxa, lacking signs of abrasion or bioerosion. The origen of the shell concentrations is
interpreted as a short-term depositional event, generated by storms, in shallow water settings under a marine transgressive regime.
The predominant taxa in the assemblage are infaunal, stenohaline bivalves that inhabit shallow sandy bottoms, with few gastropods
and epifaunal organisms. Most of the taxa have living representatives today in the southern Brazilian coast, indicating a mixture of
Argentinean and Caribbean (or Brazilian) malacological provinces. The presence of taxa that are not found living in the coast of
Rio Grande do Sul today (Anomalocardia brasiliana, Chione paphia, C. cancellata, Anadara brasiliana and Arcinella brasiliana),
suggests warmer oceanographic conditions coinciding with past sea-level highstands, also indicated by similar taxa found in fossil
concentrations in the Uruguayan and Argentinean coasts. A discussion of the stratigraphic position, age and correlation of this
assemblage with other outcrops is also presented.
barreiras arenosas que isolam diversos corpos lagunares no litoral norte do Estado, e uma extensa lagoa (Mangueira), com cerca de 100 km de extensão no litoral sul. Este setor da costa vem sendo submetido a processos dinâmicos costeiros desde o início do Holoceno que resultaram na formação de dunas eólicas.
Como resultado, a porção centro-sul da margem leste da lagoa Mangueira é caracterizada pela presença de extenso campo de dunas de grande beleza cênica, altura expressiva e importância ambiental. As dunas são habitat de diversas espécies de mamíferos, aves, insetos e plantas, contendo evidências arqueológicas da ocupação por paleo-índios. A praia oceânica adjacente ao campo de dunas é notável pela presença de
concheiros, que constituem extensas e espessas concentrações
fossilíferas de moluscos, crustáceos e vertebrados marinhos e mamíferos terrestres pleistocênicos, removidos de depósitos submersos e transportados para a praia pela dinâmica costeira.
Sistema Laguna-Barreira III, correspondente à penúltima
transgressão-regressão, acumularam-se fósseis de mamíferos extintos pertencentes à megafauna de idade Lujanense (cerca de 120.000 anos A.P.). Atualmente, esses depósitos são bem conhecidos em afloramentos ao longo das barrancas do arroio Chuí.. O estudo desses depósitos e fósseis tem fornecido valiosas informações a respeito dos aspectos paleoecológicos
e paleoclimáticos do sul do Brasil e melhorado nossa
compreensão dos processos físicos costeiros que levaram
à formação da planície costeira do Rio Grande do Sul.
extinction of all mammals with body mass >300 kg and several smaller taxa, but the driving mechanisms
behind it are still poorly understood. Here is presented an analysis of the extinction in the Pampa of
southern Brazil (Rio Grande do Sul state), based on fossil assemblages found in the coastal plain (CPRS)
and western area of the state (WRS). The comparison between fossil and extant mastofaunas show that
90% of the mammals represented in fossil assemblages went extinct, and allowed distinguishing three
groups: 1) taxa that underwent local extinction, i.e., disappeared locally but survived in other regions
until becoming extinct later (including all megamammals); 2) pseudoextinct taxa that disappeared
locally but survive until today in other areas, and 3) taxa that disappeared locally but returned during the
Holocene. The faunal changes recorded along stratigraphic successions and available numerical ages
indicate two phases of extinction, the first around 30 ka b2k in the CPRS (apparently also recorded in
Argentina and Uruguay) would have been related to the onset of the cold and dry conditions of the
stadial MIS 2, predating the arrival of humans to the region by about 25 kyrs. The second phase eliminated
taxa that survived until about 12.7 ka BP in WRS in reduced suitable environments (‘refugia’)
associated with perennial rivers; it coincides with the transition from glacial to interglacial conditions,
but pollen data suggest that humans may have contributed for environmental modifications through fire.
The results show that the Pleistocene xenarthran-dominated mastofauna was replaced by a Holocene
fauna dominated by small rodents and carnivores, and indicate that climate-driven environmental
changes, also influenced by sea-level oscillations, were a major agent in the Late Pleistocene mammalian
extinctions in the Brazilian Pampa.
RESUMO-O registro fóssil de aves do sul do Brasil é escasso e consiste de poucos elementos isolados. Aqui é descrito um fóssil de ciconídeo na assembleia de restos de mamíferos da Formação Santa Vitória. O espécime consiste de uma vértebra cervical morfologicamente similar a Ciconia maguari (joão-grande), comum atualmente no sul do Brasil. Entretanto, suas dimensões maiores sugerem que poderia ser um morfotipo daquela espécie ou outra espécie extinta. As modificações tafonômicas na vértebra resultam da combinação de fatores autogênicos e alogênicos incluindo o hábito aquático, forma e transporte por água corrente e soterramento em um riacho raso. O sedimento fossilífero datado por luminescência foi depositado no Neopleistoceno, há 37,9 ka, e exibe características que indicam deposição sob descarga variável e oscilações sazonais do lençol freático. A presença de uma ave aquática em sedimentos depositados por água indica um período de precipitação elevada, cronocorrelacionado a um dos pulsos quentes em escala milenial registrados em testemunhos de gelo da Antártica (Máximos Isotópicos Antárticos) que caracterizaram o interestadial MIS 3. Por outro lado, o clima frio e seco do glacial seguinte MIS 2 pode ter forçado os ciconídeos e mamíferos aquáticos a se retirarem para áreas adequadas (refúgios), como sugere sua ausência nos depósitos de loess (Formação Cordão) acima da FSV, até retornar durante o Holoceno, quando o clima se tornou úmido e quente novamente. Os resultados apresentados aqui ampliam o registro fóssil de aves do sul do Brasil e ajudam a compreender o papel das mudanças climáticas na distribuição de aves ciconídeas e outros táxons durante o Quaternário no sul da América do Sul. Palavras-chave: Ciconiidae, Formação Santa Vitória, tafonomia, MIS 3, paleoambiente, paleoclima.
estruturas são encontradas em diversos locais do sudeste e sul do Brasil, ocorrendo em diferentes tipos de substratos,
desobstruídas (paleotocas) ou preenchidas por sedimentos (crotovinas). A paleotoca encontrada no município de Cristal
(RS) foi escavada nos depósitos de leques aluviais terciários e marcas de garras e impressões da carapaça podem ser vistas
ao longo da superfície interna da galeria. As dimensões da estrutura, as marcas de escavação e marcas de osteodermos
presentes ao longo das paredes da paleotoca sugerem que tenha sido produzida por um xenartro dasipodídeo. A comparação
com estruturas similares encontradas na Argentina pode fornecer informações mais detalhadas a respeito da paleoecologia e
bioestratigrafia dos organismos responsáveis por sua escavação.
Sul State, southern Brazil. The concentrations were found at the same stratigraphic interval, some 7.5 m above present sea-level,
in a layer deposited in a shallow marine environment during the penultimate marine transgression around 230 ka BP and currently
exposed along the banks of Chuí Creek, located some 11 km landwards of the present coastline. The assemblage is composed
of a mixture of highly fragmented, unidentifi able shells and well-preserved bivalves and gastropods. Many bivalve remains are
complete, including juveniles and thin-shelled taxa, lacking signs of abrasion or bioerosion. The origen of the shell concentrations is
interpreted as a short-term depositional event, generated by storms, in shallow water settings under a marine transgressive regime.
The predominant taxa in the assemblage are infaunal, stenohaline bivalves that inhabit shallow sandy bottoms, with few gastropods
and epifaunal organisms. Most of the taxa have living representatives today in the southern Brazilian coast, indicating a mixture of
Argentinean and Caribbean (or Brazilian) malacological provinces. The presence of taxa that are not found living in the coast of
Rio Grande do Sul today (Anomalocardia brasiliana, Chione paphia, C. cancellata, Anadara brasiliana and Arcinella brasiliana),
suggests warmer oceanographic conditions coinciding with past sea-level highstands, also indicated by similar taxa found in fossil
concentrations in the Uruguayan and Argentinean coasts. A discussion of the stratigraphic position, age and correlation of this
assemblage with other outcrops is also presented.
Toxodon and the proboscidean Stegomastodon from Late Middle to Late Pleistocene fossiliferous beds exposed along Chuí Creek, in the coastal plain of Rio Grande do Sul State. The δ13C isotopes indicate that Toxodon was a mixed-feeder that fed mostly on C4 plants, while Stegomastodon was a browser to mixed-feeder with
preference for C3 plants, with less C4 plants in the diet compared to modern African elephants. Comparison with carbon isotopic values in fossils of these taxa from other Late Quaternary localities in South America shows an increased proportion of C3 plants in the diets of both Toxodon and Stegomastodon in higher latitudes. The values of δ18O in both taxa seem to reflect the isotopic composition of the ingested water rather than the
isotopic content in the plants of which they fed on, and the observed variations are likely to mirror variations of the patterns of precipitation. Paleoclimatic inferences and possible causes for the (pseudo)extinction of these taxa in southern Brazil are also discussed.
around the world. In Brazil such fossils are rather abundant in the southernmost portion of the coast, associated to fossiliferous concentrations at depths up to 10 m. Here is presented a review of such occurrences and the first record of fossils in deeper areas of the continental shelf. The fossils encompass several groups of both extinct and extant mammals, and exhibit several distinct taphonomic features, related to the marine environment. Those from the inner continental shelf are removed and transported
from the submarine deposits to the coast during storm events, thus forming large konzentrat-lagerstätte on the beach, called “Concheiros”. The only fossils from deeper zones of the shelf known so far are a portion of a skull, a left humerus and of a femur of Toxodon sp. and a lower right molar of a Stegomastodon
waringi, all collected by fishermen at depths around 20 m. The presence of fossils at great depths and distances from the present coastline, without signs of abrasion and far from areas of fluvial discharges does indicate that these remains have not been transported from the continent to the shelf, but have been preserved directly on the area that today correspond to the continental shelf. These remains indicate the existence of large fossiliferous deposits that have developed during periods of sealevel lowstand (glacial maxima) and have been submerged and reworked by the sea-level rise at the end of the last glaciation.
stratigraphic horizon, exhibit ages between (42 3) Ka and (34 7) Ka, using the Combination Uptake model for radioisotopes uptake, while a incisor of Toxodon platensis collected from a stratigraphic level below is much older. Fossils from the shelf have ages ranging from (7 1) 105 Ka to (18 3) Ka, indicating
the mixing of fossils of different epochs. The origen of the submarine fossiliferous deposits seems to be the result of multiple reworking and redeposition cycles by sea-level changes caused by the glacial–interglacial cycles during the Quaternary. The ages indicate that the fossiliferous outcrops at Chuı´ Creek
are much younger than previously thought, and that the fossiliferous deposits from the continental shelf encompass Ensenadan to late Lujanian ages (middle to late Pleistocene)."
reworked nature of the fossiliferous deposits in the continental shelf. Only in recent years have new data shed light on these subjects. Taxonomic revisions, ESR ages, and biostratigraphic correlations confirm a late Pleistocene age for the fossil assemblages, although those from the shelf represent a significant time averaging, while fossils from the Chuí Creek exhibit a narrower age range. The fossil mammals found in southern Brazil represent a mixture of Brazilian and Pampean taxa, including forms that disappeared much earlier from the Argentinean pampas. Gaining an understanding of the biostratigraphic context of such assemblages in comparison to similar assemblages from Argentina and Uruguay, in conjunction with stratigraphic, geomorphological, and paleoclimatic data should provide additional tools with which to reconstruct the environmental and climatic dynamics of this portion of South America during the late Pleistocene—early Holocene and its effects on the fauna, and possibly to help address the problem of
the disappearance of megamammals in the area.