Nahuel Huapi Research Articles

Zinc in an ultraoligotrophic lake food web

Zinc (Zn) bioaccumulation and trophic transfer were analyzed in the food web of Lake Nahuel Huapi, a deep, unpolluted ultraoligotrophic system in North Patagonia. Benthic macroinvertebrates, plankton, and native and introduced fish were collected at three sites. The effect of pyroclastic inputs on Zn levels in lacustrine food webs was assessed by studying the impact of the eruption of Puyehue-Cordón Caulle volcanic complex (PCCVC) in 2011, by performing three sampling campaigns immediately before and after the PCCVC eruption, and after 2years of recovery of the ecosystem. Zinc trophodynamics in L. Nahuel Huapi food web was assessed using nitrogen stable isotopes (δ15N). There was no significant increase of Zn concentrations ([Zn]) in L. Nahuel Huapi biota after the PCCVC eruption, despite the evidence of [Zn] increase in lake water that could be associated with volcanic ash leaching. The organisms studied exhibited [Zn] above the threshold level considered for dietary deficiency, regulating Zn adequately even under a catastrophic situations like PCCVC 2011 eruption. Zinc concentrations exhibited a biodilution pattern in the lake's food web. To the best of our knowledge, present research is the first report of Zn biodilution in lacustrine systems, and the first to study Zn transfer in a freshwater food web including both pelagic and benthic compartments.

Toxocariasis in Carnivora from Argentinean Patagonia: Species molecular identification, hosts, and geographical distribution.

Twenty four specimens of seven species belonging to the families Felidae, Mustelidae, and Canidae were obtained in Lanín and Nahuel Huapi National Parks from March 1996 to April 2016. Specimens were processed by necropsy in order to contribute to the knowledge of toxocariasis in wild carnivores of Argentinean Patagonia. The only Puma concolor and the seven Leopardus geoffroyi were positive for Toxocara cati. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of the ITS-1 region from larval and adult DNA was carried out to confirm parasite species identification. This is the first molecular determination of T. cati from wild felids in Argentina and the study also fill gaps about the spatial distribution and hosts for Toxocara cati.

Biological legacies promote succession and soil development on tephra from the Puyehue‐Cordon Caulle eruption (2011)

AbstractVolcanic deposits have frequently been studied from a successional point of view, but the main focus has been on vegetation dynamics, and less frequently on the development of invertebrate and microbial communities and soil properties. Biological legacies, understood as living organisms, seeds, organic debris and biologically derived patterns in soils and understories, are important in succession, and may also influence soil development on young volcanic deposits. The volcanic eruption of the Chilean Puyehue–Cordón Caulle complex (Northern Patagonia) in June 2011 deposited tephra in southern Argentina. Sandy tephra up to 30 cm deep was deposited in the De los Siete Lagos road in Nahuel Huapi and Lanín National Parks, where a road under construction had exposed sub‐soil lacking vegetation, while adjacent forest supported a canopy of Nothofagus dombeyi with Chusquea culeou in the understory. This situation provided a unique opportunity to study soil development and succession on nearby young volcanic deposits with different biological legacies, considering several biological communities. Our hypothesis is that 29 months after the eruption the tephra in the forest would have higher organic C, total N, available P and biological activity than the tephra deposited on the roadside. Plant cover and species richness, invertebrate abundance and richness, as well as substrate respiration, N mineralization and enzymatic activities were highest in the forest. In addition, organic carbon and nutrient incorporation rates in the forest were twice those in the roadside substrate. Nevertheless, two and a half years after the eruption, most variables remained an order of magnitude lower than values expected for temperate forest soils. Surviving canopy and understory play a key role in ecosystem recovery after tephra deposition, providing seeds and organic matter and establishing conditions appropriate for plants, invertebrates, and microorganisms that would in turn accelerate soil development.

Mercury in a stream-lake network of Andean Patagonia (Southern Volcanic Zone): Partitioning and interaction with dissolved organic matter

Lake Nahuel Huapi (NH) is a large, ultraoligotrophic deep system located in Nahuel Huapi National Park (NHNP) and collecting a major headwater network of Northwestern Patagonia (Argentina). Brazo Rincón (BR), the westernmost branch of NH, is close to the active volcanic formation Puyehue-Cordón Caulle. In BR, aquatic biota and sediments display high levels of total Hg (THg), ranging in contamination levels although it is an unpolluted region. In this survey, Hg species and fractionation were assessed in association with dissolved organic matter (DOM) in several aquatic systems draining to BR. THg varied between 16.8 and 363 ng L−1, with inorganic Hg (Hg2+) contributing up to 99.8% and methyl mercury (MeHg) up to 2.10%. DOC levels were low (0.31–1.02 mg L−1) resulting in high THg:DOC and reflecting in high Hg2+ availability for binding particles (partitioning coefficient log Kd up to 6.03). In streams, Hg fractionation and speciation related directly with DOM terrestrial prints, indicating coupled Hg-DOM inputs from the catchment. In the lake, DOM quality and photochemical and biological processing drive Hg fractionation, speciation and vertical levels. Dissolved gaseous Hg (Hg0) reached higher values in BR (up to 3.8%), particularly in upper lake layers where solar radiation enhances the photoreduction of Hg2+ and Hg-DOM complexes. The environmental conditions in BR catchment promote Hg2+ binding to abiotic particles and bioaccumulation and the production of Hg0, features enhancing Hg mobilization among ecosystem compartments. Overall, the aquatic network studied can be considered a “natural Hg hotspot” within NHNP.

Marcas y atractivos en una provincia imaginada. Río Negro, Argentina, 1958-1976

This manuscript crosses political history with cultural history. It searches the political and territorial order in Rio Negro Province since its definition about touristic attractive, because that cultural marks become in political ones. This jurisdiction contains one of the most emblematic tourist center: the town of San Carlos de Bariloche and a portion of the Nahuel Huapi National Park. But this area was not taken into account as a scenic reference of the touristic attraction of the Province. The regions presented as the image of Rio Negro emerge from politics interest established by the provincial government. The article shows that the political order, and even the citizen construction that was sought to promote in the constitutive period of the province, dialogued and was in based on the specific form of recognition of attractions established since provincial planning, which didn’t take into consideration the Andean space. The internal political construction was focused on other regions. Thus, the attractions were constituted from the political interests established by the provincial government, rather than by the materiality that was promoted.

Silver bioaccumulation in chironomid larvae as a potential source for upper trophic levels: a study case from northern Patagonia.

Silver (Ag) is a pollutant of high concern in aquatic ecosystems, considered among the most toxic metallic ions. In lacustrine environments, contaminated sediments are a source of Ag for the food web. Chironomidae (Insecta: Diptera) are the most abundant, diverse, and representative insect groups in aquatic ecosystems. Chironomid larvae are closely associated to benthic substrates and link primary producers and secondary consumers. Given their trophic position and their life habits, these larvae can be considered the entry point for the transference of Ag, from the benthic deposit to the higher trophic levels of the food web. Previous studies in lakes from Nahuel Huapi National Park (Northern Patagonia) showed Ag enrichment over background levels (0.04-0.1μgg-1 dry weight) both in biota (bivalves and fish liver) and sediments from sites near human settlements. The aim of this study was to analyze the role of chironomids in the transference of Ag from the benthic reservoir of Lake Moreno Oeste to the food web. The concentration of Ag in chironomid larvae tissue ranged from 0.1 to 1.5μgg-1 dry weight, reaching a bioaccumulation factor up to 17 over substrates and depending on the associated substrate type, feeding habitats, larval stage, and season. The main Ag transfer to higher trophic levels by chironomids occurs in the littoral zone, mostly from larvae inhabiting submerged vegetation (Myriophyllum quitense) and sediment from vegetated zones. This study presents novel evidence of the doorway role played by chironomid larvae in Ag pathways from the sediments into food webs of freshwater ecosystems.

Species- and habitat-specific bioaccumulation of total mercury and methylmercury in the food web of a deep oligotrophic lake

Niche segregation between introduced and native fish in Lake Nahuel Huapi, a deep oligotrophic lake in Northwest Patagonia (Argentina), occurs through the consumption of different prey. Therefore, in this work we analyzed total mercury [THg] and methylmercury [MeHg] concentrations in top predator fish and in their main prey to test whether their feeding habits influence [Hg].Results indicate that [THg] and [MeHg] varied by foraging habitat and they increased with greater percentage of benthic diet and decreased with pelagic diet in Lake Nahuel Huapi. This is consistent with the fact that the native creole perch, a mostly benthivorous feeder, which shares the highest trophic level of the food web with introduced salmonids, had higher [THg] and [MeHg] than the more pelagic feeder rainbow trout and bentho-pelagic feeder brown trout.This differential THg and MeHg bioaccumulation observed in native and introduced fish provides evidence to the hypothesis that there are two main Hg transfer pathways from the base of the food web to top predators: a pelagic pathway where Hg is transferred from water, through plankton (with Hg in inorganic species mostly), forage fish to salmonids, and a benthic pathway, as Hg is transferred from the sediments (where Hg methylation occurs mostly), through crayfish (with higher [MeHg] than plankton), to native fish, leading to one fold higher [Hg].

Reconstructing recent environmental changes using non-biting midges (Diptera: Chironomidae) in two high mountain lakes from northern Patagonia, Argentina

Fil: Montes de Oca, Fernanda. Administracion de Parques Nacionales; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina

La activación de un patrimonio nacional en Norpatagonia, Argentina

En este artículo se analizan aspectos relativos a la creación de las áreas protegidas en Argentina, en ligazón con el proceso de construcción del Estado y de consolidación de la Nación en Norpatagonia. Recuperamos la figura de Francisco Moreno y de Exequiel Bustillo, dos personajes clave en la creación de las mismas y en la impronta simbólica y estética otorgada a la Patagonia argentina. Se sostiene que a partir de sus trayectorias, vinculaciones políticas y propuestas se sentaron las bases del ideario fundacional de los Parques Nacionales, las cuales destacaban el rol de la naturaleza como inspiradora de los valores de la patria. Asimismo, se utiliza la categoría de analítica de “activación patrimonial” con el objeto de ahondar en el interrogante acerca de por qué ciertos espacios naturales son valorados como patrimonio del conjunto de la nación y por ende deben ser preservados. Los resultados que aquí se presentan provienen del trabajo con fuentes documentales y de entrevistas en profundidad, en el marco de una investigación en el Departamento Los Lagos, provincia de Neuquén, Argentina, territorio que integra el Parque Nacional Nahuel Huapi.

Changes in the natural dynamics of Nothofagus dombeyi forests: population modeling with increasing drought frequencies

AbstractDrought‐induced episodes of tree mortality can determine forest dynamics and structure, particularly in forests dominated by single species. Short‐ and mid‐term climate projections indicate that strong changes in annual precipitation may strike more often in northern Patagonia. Data for recruitment, growth, and survival of Nothofagus dombeyi tree individuals were collected at several sites across the Nahuel Huapi National Park in Argentina. We combined mathematically all these different demographic stages into an Integral Projection Model to simulate 100‐yr projections of simulated stand structure under different frequencies of extreme drought episodes. We projected total basal area and the number of individuals for three different initial stand types (i.e., young, medium, and old) and for varying drought frequencies (i.e., from 1 to 5 drought events every 100 years). Recruitment into the dbh ≥ 10 cm size class under normal conditions (i.e., without drought) was higher than under episodic drought conditions. In addition, survival under normal conditions was higher than under drought conditions, especially for small trees. Differences in growth were also important, with trees growing more vigorously under normal than under drought conditions. Our simulations predicted that N. dombeyi populations would experience a reduction in tree density in the mid‐term if, as predicted by the IPCC projections, the frequency of future drought events increased. The simulations also showed that in those cases, young stands should suffer the most. Drought‐mediated changes may induce a decline in the development of N. dombeyi forests in the mid‐ and long term by a drastic reduction in tree density.

Variations in anthropogenic silver in a large Patagonian lake correlate with global shifts in photographic processing technology

At the beginning of the 21st century, digital imaging technology replaced the traditional silver-halide film photography which had implications in Ag contamination. Lake Nahuel Huapi is a popular Patagonia tourist destination impacted by municipal silver (Ag) contamination from photographic processing facilities since 1990's. Silver concentrations in a dated sediment core from the lake bottom showed a 10-fold increase above background levels in the second half of the 20th century, then a decrease. This trend corresponds well with published annual global photography industry demand for Ag, which clearly shows the evolution and replacement of the traditional silver-halide film photography by digital imaging technology. There were significant decreases in Ag concentrations in sediments, mussels and fish across the lake between 1998 and 2011. Lower trophic organisms had variable whole-body Ag concentrations, from 0.2–2.6 μg g−1 dry weight (DW) in plankton to 0.02–3.1 μg g−1 DW in benthic macroinvertebrates. Hepatic Ag concentrations in crayfish, mussels and predatory fish were significantly elevated relative to muscle which often have Ag concentrations below the detection limit (0.01–0.05 μg g−1 DW). Trophodynamic analyses using δ15N and whole-body invertebrate and muscle Ag concentrations indicated food web biodilution trends. High sedimentation rates in conjunction with the reduction of silver waste products discharged to the lake, as a result of the change to digital image processing technologies, are resulting in unplanned but welcome remediation of the Ag contamination in Lake Nahuel Huapi.

Contrasting responses of lake ecosystems to environmental disturbance: a paleoecological perspective from northern Patagonia (Argentina)

Paleoecological studies are crucial for understanding ecosystem disturbance and resilience dynamics. However, nearly all the research related to the response of aquatic communities to disturbances has been developed at short-term ecological scales. In this study, we investigate the long-term response of chironomid insects of two lakes, to volcanic and other environmental disturbances that have taken place during the last 200 years. The studied lakes, Lake Verde and Lake Toncek, are located in the Nahuel Huapi National Park (northern Patagonia, Argentina), under contrasting environmental settings. Our results show that the main driver of faunal changes in both lakes is volcanism. Indeed, after the impact of the 1960 Puyehue/Calbuco volcanic events, the chironomid assemblage of Lake Verde recovered to initial conditions showing high resistance and a strong resilience to the impact. In this lake, the canopy, the presence of macrophytes, and the dynamic of the watershed are important determinants of resilience providing habitats for species colonization and/or by giving refugia to the community. Contrarily, chironomid assemblages from Lake Toncek did not recover to the original state after the impact of the ash. This lake is located above the tree line, and therefore it is highly probable that the lack of vegetation cover in the basin offered no protection for the aquatic environment, leaving the ecosystem highly exposed to the effect of the volcanic ashes. Subordinate to the effects of the volcanism, rising temperatures in the last 50 years and/or increasing human activities in the area, especially in L. Toncek, may also be responsible for the changes in chironomid assemblages.

Holocene tephra succession of Puyehue-Cordón Caulle and Antillanca/Casablanca volcanic complexes, southern Andes (40–41°S)

Puyehue-Cordón Caulle and Antillanca volcanic complexes are two of at least 50 active frontal arc volcanoes that define the 1400km-long Southern Volcanic Zone of Chile. Holocene tephra deposits in Chile and Argentina (40–41°S) up to 100km east of these volcanoes comprise at least five voluminous (~1 to ~8km3) pyroclastic-fall layers that preceded several recently deposited Cordón Caulle pumice fallouts. Field observations of proximal, medium, and distal facies of the deposits, in conjunction with geochronology and geochemistry of the volcanic complexes, indicate that three fall layers are derived from Puyehue volcano (Puyehue 1 and 2, and Mil Hojas), whereas two are sourced from the Antillanca complex (Playas Blanca-Negra, and Nahuel Huapi Tephra), 20km to the south. The oldest tephra (calibrated 14C age 10.49±0.12ka, 2σ), found only at medium-distal facies, is deposited directly on granitic moraine boulders and consists of deeply weathered, orange dacitic pumice lapilli. The next prominent tephra at ~7ka comprises dacitic pumice and its age is equivalent to a rhyodacitic dome exposed in the Puyehue summit crater. Above these deposits there are phases of a complex eruption consisting of a conspicuous compositionally-zoned tephra. It also comprises a pyroclastic density current, together with lithic rich and scoriaceous fallout deposits. Mineralogical, geochemical, and Sr isotope evidence, plus the isopach maps, confirm that this sequence of eruptive events is sourced from Antillanca at 1932±68yrBP. The total volume of this eruptive sequence exceeds 8km3, making it the largest Holocene eruption from either volcanic complex. This eruption was likely responsible for the destruction of an ancestral Antillanca volcano and the formation of a 4.5km diameter caldera. A distinctive younger unit in the region is a voluminous rhyodacitic pumice fall (calibrated 14C age 1.11±0.07ka), above which a series of several alternating dark lithic and pumice lapilli beds accumulated. Correlation with proximal deposits indicates that the 1.11ka eruption was derived from Puyehue and destroyed ~3km3 of rhyodacitic domes at this volcano summit. Historic explosive activity at the nascent Casablanca volcano and along Cordón Caulle, including the 2011–2012 eruption (~1km3 of uncompacted pumice), the largest from this fissural zone, emphasizes an increased risk for volcanic hazards in central Chile and Argentina.

Effects of volcanic ash on assemblage patterns and biological traits of Chironomidae in a north Andean Patagonian stream, Argentina

The Puyehue-Cordon Caulle Volcanic Complex eruption occurred on June 4, 2011 (2236 m a.s.l. 40°32′S, 72°7′W). As a consequence, wide areas of Argentina were covered by volcanic ash. In order to investigate the effects of ashfall on chironomid assemblages, we conducted a study at Nireco River in the southwestern part of the Natural Reserve of Nahuel Huapi National Park that crosses the city of San Carlos de Bariloche, Rio Negro, Argentina. We assessed changes in chironomid assemblage attributes and 18 biological traits, by comparing pre-eruption data (December 2009 and December 2010) with post-eruption data (November 2011). Volcanic ash caused negative effects on the chironomid assemblages, where richness and density decreased significantly and the subfamilies Podonominae, Tanypodinae and Chironominae disappeared. The ordination method (principal component analysis) based on abundance of taxa and functional trait composition distinguished pre-eruption from post-eruption periods. Specific tolerance to sedimentation was related to traits mostly associated with predaceous habits such as small size, large head, retractile antennae, long prolegs, presence of ligula and long apical mandibular tooth.

Occurrence of arbuscular mycorrhizal fungi in high altitude sites of the Patagonian Altoandina region in Nahuel Huapi National Park (Argentina)

Fil: Velazquez, Maria Silvana. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Botanica Spegazzini; Argentina

Mercury and selenium in the food web of Lake Nahuel Huapi, Patagonia, Argentina

Despite located far from point sources of Hg pollution, high concentrations were recorded in plankton from the deep oligotrophic Lake Nahuel Huapi, located in North Patagonia. Native and introduced top predator fish with differing feeding habits are a valuable economic resource to the region. Hence, Hg and Se trophic interactions and pathways to these fish were assessed in the food web of this lake at three sites, using stable nitrogen and carbon isotopes.As expected based on the high THg in plankton, mercury did not biomagnify in the food web of Lake Nahuel Huapi, as most of the THg in plankton is in the inorganic form. As was observed in other aquatic systems, Se did not biomagnify either.When trophic pathways to top predator fish were analyzed, they showed that THg biomagnified in the food chains of native fish but biodiluted in the food chains of introduced salmonids. A more benthic diet, typical of native fish, resulted in higher [THg] bioaccumulation than a more pelagic or mixed diet, as in the case of introduced fish.Se:THg molar ratios were higher than 1 in all the fish species, indicating that Se might be offering a natural protection against Hg toxicity.

Does Type of Substratum Affects Chironomid Larvae Assemblage Composition? A Study in a River Catchment in Northern Patagonia, Argentina.

Chironomid larvae assemblages were investigated at seven sampling stations in relation to stream habitat type in the Challhuaco-Ñireco river system located in the Nahuel Huapi National Park, in the North-Western part of Rio Negro Province, Argentina. A total of 2229 individuals were sampled and 43 Chironomidae taxa were recorded with Orthocladiinae (29) being the best represented subfamily, followed by Diamesinae (5), Tanypodinae (3), Podonominae (3) and Chironominae (3). Stictocladius spF, Cricotopus (Paratrichocladius) sp6, Cricotopus sp2, Cricotopus sp3 and Parapsectrocladius sp2 were the most abundant taxa. Sites near the source of the river system were dominated by Podonomus sp., Limnophyes sp., Parapsectrocladius sp. and Stictocladius spF, whereas sites close to the river mouth were dominated by Diamesinae sp5 and Cricotopus sp. Rank/abundance plots show that all the analysed sites displayed dominance of some species. Stictocladius spF, Cricotopus sp2, Cricotopus sp3, Cricotopus (Paratrichocladius) sp6, Parapsectrocladius sp. and Limnophyes sp. resulted as dominant species, or being part of a group of dominant species, at least in one sample. Eleven taxa were associated with habitats related with riffle areas and stable substrates with filamentous algae. Species-environment relationships were examined using ordination analysis. Elevation was the most significant environmental variable that explained 22% of the total variability of the chironomid assemblages, showing stronger relationships among sites within an altitudinal gradient than among habitat type. Abundance of chironomids increased from headwaters to the outflow in Nahuel Huapi Lake responding to an altitude gradient as well as some environmental factors such as coarse matter and nutrient concentrations.

Chironomids as indicators of natural and human impacts in a 700-yr record from the northern Patagonian Andes

Chironomid communities were studied in a sediment core collected from Lake Moreno Oeste, located in Nahuel Huapi National Park. A major change in midge assemblages occurred at ∼AD 1760, which was characterized by a decrease of “cold taxa” including Polypedilum sp.2 and Dicrotendipes, and an increase of “warm taxa” including Apsectrotanypus and Polypedilum sp.1. These taxa are likely related to climatic conditions concurrent with the end of a cold period at ∼AD 1500–1700 and the beginning of a drying climate at ∼AD 1740–1900 in northern Patagonia. Coarse tephra layers had low midge diversity; however they did not disrupt the climatic trend as the community recovered rapidly after the event. Since AD 1910, after the increase in suburban housing, fish introduction, and the construction of a road, there was an increase in the relative abundances of taxa typically associated with the littoral zone, such as Parapsectrocladius, Riethia, Apsectrotanypus, and some Tanytarsini morphotypes. The main change in the chironomid community appears to be associated with long-term climate change. At the beginning of the 20th century, other site-specific environmental factors (catchment change and fish introduction) altered the chironomid assemblages, making it more difficult to understand the relative importance of each driver of assemblage change.

Characterization of freshwater changes in lakes of Nahuel Huapi National Park produced by the 2011 Puyehue–Cordón Caulle eruption

This work supplies a characterization of the chemical properties, including data of dissolved major and minor components in surface and pore water collected in Argentinean lakes surrounding the impacted area of Puyehue-Cordón Caulle volcanic complex, in the 2011 eruption. The principal component analysis and Pollution Load Index were used for the identification of water changes by volcanic ashes deposited throughout 1year of eruption. The element content between water column and pore water provided a direct evidence of the potential dissolution of the element. Many chemical transformations, after the pyroclastic material contacted with the freshwater, were observed such as large pH changes from 3.2 to 8.1, electrical conductivity of 28.9 to 457μs/cm, and redox potential of 171 to 591mV. The maximum concentrations measured of F, Al, and Hg were 600, 40, and 0.0382μg/L respectively. These concentrations in water column were lower than the limit of aquatic life protection for chronic toxicity. The Pollution Load Index indicated very low pollution for sites far away from the volcano and moderated pollution in closely sites. The processes were stabilized at the end of the monitoring, 1year after the eruption.

Geographical and geological explorations of the La Plata Museum 1884–1905

Abstract The contributions of the La Plata Museum to the geology of Argentina began following the exploratory trips of its founder, F.P. Moreno, in the 1870s. The geological expeditions of the La Plata Museum started in the 1880s and covered the Andean region, although they were focused in the Patagonian Andes. They became more important from 1893 when they were related to explorations aimed at fixing the boundary between Argentina and Chile. Within 10 years the geographical and geological bases of large and almost unknown regions were established. R. Hauthal studied the area between the Last Hope Inlet and Lake Belgrano, defining its stratigraphy and publishing the first geological map of the Cordilleran region between c. 49° 30′ and 52° S. The geology between Lake Buenos Aires and the Rio Negro (41–47° S) was established by Santiago Roth. The stratigraphic succession, facies and structural changes through the Argentine–Chilean Cordillera at the latitude of Lake Nahuel Huapi and Lake Lacar were studied by L. Wehrli, while studies at the latitude of Neuquén and Mendoza (36–39° S) were carried out by C. Burckhardt. Mesozoic and Cenozoic fossils were studied either in the Museum or abroad. Supplementary material: Map of southern South America (Argentina and Chile) showing the distribution of towns in 1870 is available at https://doi.org/10.6084/m9.figshare.c.3283385.v1