The extinction of the Pleistocene megafauna in the Pampa of southern Brazil
Introduction
The Late Quaternary Extinction (LQE) in the Americas has been a subject of discussion among scientists of different fields in the last decades (Martin and Klein, 1984; Koch and Barnosky, 2006; Haynes, 2009), focusing mainly on the cause(s) of extinction, with climate change or overhunting by humans being advocated as the most probable agents. Although the extinction is regarded as having occurred during the Pleistocene-Holocene transition (∼12.4–7.8 ka BP), relatively little is known about the exact timing of the process. Some models advocate a relatively sudden extinction, occurring shortly after the arrival of humans (Martin, 1973; Brook and Bowman, 2002; Steadman et al., 2005), whereas models based on absolute ages show thousands of years of coexistence between humans and megamammals prior to the extinction (Barnosky and Lindsey, 2010). The question of the timing is of major importance, because it could indicate whether the extinction was sudden or protracted, or if it was synchronous or occurred at different times in different areas across the continent. It could also help assessing the mechanism(s) of extinction by allowing correlation with environmental changes or human occupation obtained from other paleo-records.
This extinction was responsible for a dramatic change in the composition of mammalian communities (faunal turnover) and has received much attention not only because it potentially could have been linked to human dispersal or to climate change, but also because it wiped away mostly large mammals, thus deeply influencing the character of the modern ecosystems and terrestrial communities. The turnover was particularly striking in South America, where some 80% of the large-bodied mammals (body mass ≥ 44 kg) and 100% of the megamammals (body mass ≥ 1,000 kg) disappeared (Cione et al., 2009).
In Brazil, little is known so far about the LQE, mostly because researches have historically focused on systematics. Moreover, the lack of good stratigraphic records with associated numerical ages in several Quaternary deposits makes difficult to assess faunal dynamics and correlate extinctions with specific environmental changes that could be inferred from sedimentary records. Because of these deficiencies, it has been difficult to establish the temporal range represented by most of the Pleistocene-Holocene fossil assemblages, which were regarded as ‘pontual’ in time (Cartelle, 1999), but now recognized as representing longer intervals (Auler et al., 2006).
In southern Brazil, the Pleistocene fossiliferous sites better characterized in terms of stratigraphy and chronology are found across the Pampa landscape, in the state of Rio Grande do Sul (Fig. 1), where two fossiliferous units have been studiedwere described. In the western part of the state (WRS), the Touro Passo Formation (TPF) outcrops along the Touro Passo Creek (Bombin, 1976; Oliveira and Kerber, 2009; Kerber et al., 2014), whereas the Santa Vitória Formation (SVF) outcrops along Chuy Creek in the coastal plain (CPRS) to the east (Soliani, 1973; Soliani and Jost, 1975). The mammalian fossil record of the CPRS also includes specimens found on the continental shelf (CS) and modern beaches, but these lack defined stratigraphic setting (Lopes and Buchmann, 2010; Aires and Lopes, 2012; Cruz et al., 2017).
The aim of this paper is to describe the Late Pleistocene-Early Holocene mammalian turnover recorded in the Pampa of southern Brazil, based on an integrative approach that included a survey of the fossil mammalian assemblages of the CPRS and WRS, analysis of the stratigraphic distribution and age of the deposits and associated fossils, comparison between the extinct and extant mastofauna, and assessment of pattern of faunal changes recorded in those units within a chronostratigraphic framework. A comparison of the pattern of faunal turnover and its chronostratigraphic setting with the available archaeological and paleoclimatic records is also presented, in order to identify possible mechanisms that could have driven the Late Pleistocene extinction in the Brazilian Pampa.
Section snippets
Methods
Traditionally, the main focus of studies about the Pleistocene fauna of southern Brazil has been systematics (e.g. Paula Couto, 1953; Souza Cunha, 1959; Oliveira, 1992). The research program focused on Quaternary deposits of Rio Grande do Sul that has been developed for the last ten years broadened the spectrum of disciplines and methods employed, including stratigraphy, chronology, taphonomy and paleoecology (Da Rosa, 2009; Kerber et al., 2011; Lopes, 2013; Lopes et al., 2010, 2013; 2014a,
Regional setting
The Pampa landscape of South America is a low relief area with altitudes between 0 and 1,300 m stretching across Rio Grande do Sul state in Brazil, Uruguay and Argentina (Fig. 1A). The Pampa encompasses an area of some 178,000 km2 across the southern half of Rio Grande do Sul state (IBGE, 2019), bordered to the north by the Araucárias Plateau (Fig. 1B). The Pampa is occupied by a grassland biome with herbaceous and shrubby formations, and sparse arboreal vegetation concentrated mostly along
Ages and biostratigraphy of the fossil assemblages and fossil-bearing units
The fossil teeth from the CS dated by ESR exhibit a wide age range (Fig. 2C). Some specimens are chronocorrelated to those of the SVF (207 ± 28, 165 ± 28 and 146 ± 9 ka), whereas others are much older (650 ± 100, 464 ± 65 and 428 ± 30 ka), and one tooth of a mastodont is much younger, being dated as of 18 ± 3 ka (Lopes et al., 2010). These ages correspond to late interglacial or glacial epochs, when sea-level was much lower (up to about −130 m) than the present one (Rohling et al., 1998).
The
Discussion
The diverse Chuy Creek local fauna is the assemblage of Pleistocene mammals in southern Brazil better known so far in terms of stratigraphic resolution and chronology. Despite the diversity of the assemblages from the continental shelf and Touro Passo Creek, these lack stratigraphic resolution to allow recognizing faunal changes through time. Nevertheless, the available absolute ages from these deposits allow establishing chronostratigraphic comparisons with the fossils from the SVF.
Faunal
Conclusions
The fossil assemblages of mammals within defined stratigraphic successions, temporally calibrated by numerical ages, allows assessing the faunal turnover caused by the extinction of the megafauna between the Late Pleistocene and Early Holocene across the Pampa of southern Brazil. This extinction was characterized by the disappearance of all megamammals and several large taxa, comprising 90% of the paleomastofauna, whereas small taxa (mostly rodents) were less affected. It dramatically changed
Declaration of competing interest
The authors declare no conflict interest.
Acknowledgments
The authors would like to thank Dr. Jairo Savian (Universidade Federal do Rio Grande do Sul) for providing two of the OSL datings mentioned in the text. This research was funded by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) through the Postdoctoral Research Grant no. 150153/2014-7 to R.P. Lopes, and Research Fellowship no. 305393/2017-0 to S.R. Dillenburg.
References (242)
- et al.
The Greenland Ice Core Chronology 2005, 15-42ka. Part 1: constructing the time scale
Quat. Sci. Rev.
(2006) - et al.
A critical review of mid- to late-Holocene sea-level fluctuations on the eastern Brazilian coastline
Quat. Sci. Rev.
(2006) - et al.
U-Series dating and taphonomy of Quaternary vertebrates from Brazilian caves
Palaeogeogr. Palaeoclimatol. Palaeoecol.
(2006) - et al.
Timing of Quaternary megafaunal extinction in South America in relation to human arrival and climate change
Quat. Int.
(2010) - et al.
Patterns of faunal turnover and diversity in the neogene siwaliks of northern Pakistan
Palaeogeogr. Palaeoclimatol. Palaeoecol.
(1995) South and southeast Brazilian grasslands during Quaternary times: a synthesis
Palaeogeogr. Palaeoclimatol. Palaeoecol.
(2002)- et al.
Late Quaternary grassland (campos), gallery forest, fire and climate dynamics, studied by pollen, charcoal and multivariate analysis of the São Francisco de Assis core in western Rio Grande do Sul (southern Brazil)
Rev. Palaeobot. Palynol.
(2005) - et al.
The Late Pleistocene/Early Holocene archaeological record in Brazil: a geo-referenced database
Quat. Int.
(2013) - et al.
A new Pleistocene bird assemblage from the southern pampas (Buenos Aires, Argentina)
Palaeogeogr. Palaeoclimatol. Palaeoecol.
(2015) Nature of environmental changes in south America at the last glacial maximum
Palaeogeogr. Palaeoclimatol. Palaeoecol.
(1993)
A stalagmite record of changes in atmospheric circulation and soil processes in the Brazilian subtropics during the Late Pleistocene
Quat. Sci. Rev.
Paleoecology and radiocarbon dating of the Pleistocene megafauna of the Brazilian intertropical region
Quat. Res.
The complex prograded Cassino barrier in southern Brazil: geological and morphological evolution and records of climatic, oceanographic and sea-level changes in the last 7-6 ka
Mar. Geol.
ESR dating of late Quaternary megafauna fossils from João dourado, Bahia, Brazil
J. S. Am. Earth Sci.
A model for the Holocene extinction of the mammal megafauna in Ecuador
J. South Am. Earth Sci.
How marine isotope stage 3 (MIS3) is reflected in northern mesopotamia faunal assemblage of Argentina: the Xenarthra cingulata case
Quat. Int.
Southern westerlies during the last glacial maximum
Quat. Res.
Insights into Holocene megafauna survival and extinction in southeastern Brazil from new AMS 14C dates
Quat. Res.
Glacier modeling and the climate of patagonia during the last glacial maximum
Quat. Res.
The last glacial maximum and deglaciation in southern South America
Quat. Sci. Rev.
Climatic changes in the South American plains: records of a continental-scale oscillation
Quat. Int.
Electron Spin Resonance dating of the southern Brazilian Pleistocene mammals from Touro Passo Formation, and remarks on the geochronology, fauna and palaeoenvironments
Quat. Int.
Electron spin resonance dating of human teeth from Toca da Santa shelter of São Raimundo Nonato, Piauí, Brazil
Nucl. Instrum. Methods Phys. Res. B
Dating human occupation at Toca do Serrote das Moendas, Sao Raimundo Nonato, Piauí, Brasil by electron spin resonance and optically stimulated luminescence
J. Hum. Evol.
Drought-response strategies of savanna herbivores
Ecol. Evol.
Representativity of Quaternary mammals from the southern Brazilian continental shelf
Rev. Bras. Palaontol.
Middle Eocene rodents from Peruvian Amazonia reveal the pattern and timing of caviomorph origins and biogeography
Proc. Royal Soc. B
Wild felid range shift due to climatic constraints in the Americas: a bottleneck explanation for extinct felids?
J. Mamm. Evol.
Interhemispheric synchrony of Late-glacial climatic instability as recorded in proglacial Lake Mascardi, Argentina
J. Quat. Sci.
Facilitation versus competition in grazing herbivore assemblages
Oikos
Lama guanicoe. The IUCN Red List of Threatened Species 2016: e.T11186A18540211
Erosional features of the eastern margin of the Patos Lagoon, southern Brazil: significance for Holocene history
J. Coast Res.
Cronoestratigrafia da Bacia de Pelotas: uma revisão das sequências deposicionais
Gravel
800,000 years of abrupt climate variability
Science
Milankovitch and climate - understanding the response to astronomical forcing - Part 2
NATO ASI Series, C
Mammalian response to cenozoic climatic change
Annu. Rev. Earth Planet Sci.
Modelo paleoecológico evolutivo para o Neoquaternário da Campanha - oeste do Rio Grande do Sul (Brasil). A Formação Touro Passo, seu conteúdo fossilífero e a pedogênese pós-deposicional
Evidências paleoclimáticas em solos do Rio Grande do Sul
The elusive evidence: the archeological record of the south American extinct megafauna
Primeros registros de Glyptatelinae cuaternários (Mammalia, Xenarthra), para el Cono Sur de Sudamérica
Insolation changes, ice volumes, and the O18 record in deep-sea cores
Rev. Geophys. Space Phys.
Explaining the Pleistocene megafaunal extinctions: models, chronologies, and assumptions
Proc. Natl. Acad. Sci. Unit. States Am.
What do we know about Pteronura brasiliensis in Uruguay?
Lat. Am. J. Aquatic Mamm.
Estratigrafia e evolução da barreira holocênica na região costeira de Santa Vitória do Palmar, Planície Costeira do Rio Grande do Sul
Pleistocene mammals of the cerrado and caatinga of Brazil
Understanding plant responses to drought - from genes to the whole plant
Funct. Plant Biol.
Chronostratigraphy and "Land-Mammal ages" in the cenozoic of southern South America: principles, practices, and the "uquian" problem
J. Paleontol.
Biostratigraphy and chronological scale of upper-most cenozoic in the pampean area, Argentina
Occurrence charts of Pleistocene mammals in the Pampean area, eastern Argentina
The Broken Zig-Zag: late Cenozoic large mammal and tortoise extintion in South America
Revista del Museo Argentino de Ciencias Naturales
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