Brazilian Intertropical Region Research Articles

Mangy armadillos: New records of Karethraichnus minimum in extinct quaternary pampatheres of the Brazilian intertropical region

This paper presents pathological lesions in the osteoderms of three extinct pampatheres: two specimens of the genus Holmesina sp. and one specimen of Pampatherium humboldtii, which lived in the Brazilian Intertropical Region. The traces analyzed here were attributed to the ichnospecies Karethraichnus minimum and were associated with the behavior of ectoparasites, such as fleas, likely belonging to the genus Tunga. Some osteoderms also present ulcerative lesions, possibly generated by the action of microorganisms such as bacteria and fungi. These new records expand our knowledge about the paleopathologies caused by fleas in extinct pampatheriids, demonstrating that such occurrences were common.

Potential historically intertropical stable areas during the Late Quaternary of South America

AbstractSouth America is a pivotal paleontological setting for Late Quaternary megafaunal research. Nonetheless, its paleobiogeography and paleoecology, and the causes for the recent extinction of megafauna in the Late Pleistocene/Early Holocene are not yet fully understood. This study aimed to investigate the potential geographical distribution and historically intertropical stable areas (HISAs) of South American megafauna. We generated maps using Paleo‐Species Distribution Models for 12 megafaunal taxa (11 herbivores and one carnivore) during interglacial and glacial periods in the Late Quaternary: 120 and 21 ka. Our models, together with isotopic data, show that the HSIAs occurred mainly in low‐altitude plains (<1000 m) and were superimposed on seasonal dry forest biomes. We propose the occurrence of two HSIAs: the West Intertropical Region and the Brazilian Intertropical Region, the latter being redefined. We suggest that the Brazilian Intertropical Region is much smaller than previously proposed, but was still a key zoogeographical region for megafauna in South America during the Late Pleistocene.

Tracking the past: Isotopic paleoecology (δ13C, δ18O) of the Late Pleistocene megafauna from northeast of South America

Fossils from natural tanks can contribute to the paleoenvironmental interpretation of the Brazilian Intertropical Region (BIR), an important study area for the Quaternary in South America. In this paper we present results of δ13C and δ18O for Eremotherium laurillardi (δ13C = −4.6 ‰, δ18O = 33.0 ‰), Toxodon platensis (δ13C = −3.8 ‰, δ18O = 35.5 ‰), and Notiomastodon platensis (δ13C = −2.9 ‰, δ18O = 31.6 ‰) from Zabelê tank, compared to other localities, suggesting that these taxa had a mixed-feeder diet with a higher consumption of C4 plants (pi > 60%), living in a transition zone between woodland savannah and open savannah. The Zabelê tank, northeastern Brazil, presents Optically Stimulated Luminescence ages ranging from 41.2 to 30.4 ky (Lujanian Stage/Age; Late Pleistocene). The origin of the fossiliferous layer through debris flow suggests short periods of intense rainfall under drier climatic conditions. Compared to other locations in the BIR, Zabelê documented a drier climate (δ18O = 31.6–33.4 ‰), which preceded the last glacial maximum. These new isotopic data to OSL ages associated with previous data from the BIR contribute to the understanding of the paleoecology and paleoenvironment dynamics of South America.

Annual isotopic diet (δ13C, δ18O) of Notiomastodon platensis in the Brazilian Intertropical region during the Last Glacial Maximum

Notiomastodon platensis was a Pleistocene proboscidean endemic to South America, and until now, the unique proboscidean taxon recognized in Brazil, representing one of the most important herbivorous megamammals present in the Brazilian Intertropical Region (BIR). The aim of this study was to analyze δ13C and δ18O isotopic signatures from samples from two dentin incremental layers of an individual tusk from the Sousa municipality (Paraíba State, Brazil), in order to infer diet, niche breadth, and paleoenvironment. Radiocarbon dating suggests that the studied individual lived in the Last Glacial Maximum age (24,190–24,567 Cal yr BP), and probably had a mixed-feeder diet with slightly higher consumption of C3 plants (δ13C = −7.5 ± 0.2‰, pi = 68%) during two years of its life. We suggest a generalist habit (BA = 0.83) for this individual, similar to the results found for this species in other BIR locations. In addition, we suggest that the individual from Sousa/PB lived in a wetter environment (δ18O = 27.2 ± 0.5‰) when compared to other localities in the BIR.

Record of a juvenile of Ahytherium aureum from the Late Pleistocene of the Brazilian Intertropical Region: radiocarbon dating, isotopic palaeoecology and evidence of predation by a Felidae

AbstractTeeth and bone remains belonging to the juvenile Megalonychidae family were found in Engrunado cave (Nova Redenção, Bahia, Brazil). We propose an index between the mesiodistal/vestibulo‐lingual measurements of caniniforms and molariforms (Imd/vl) to differentiate isolated teeth of Ahytherium aureum and Australonyx aquae, and based on this index, we suggest that the fossil material belonged to A. aureum. The diaphysis of the right humerus of A. aureum presents biogenic marks assigned to the ichnospecies Nihilichnus nihilicus, suggesting dietary interactions and potential predation by a large felid. Radiocarbon dating and carbon and oxygen isotopic analyses suggest that this individual lived in the region between 36 181 and 41 094 Cal yr bp, feeding on C3 plant resources (fruit and leaves) in a low‐density forest. The revision of radiocarbon dating and carbon and oxygen isotopes for some species found in the Engrunado cave and in the nearby Marota cave enables a climate reconstruction and indicates the maintenance of a forested environment in the region between 15 and 40 kyr.

Taphonomy, paleoecology and chronology of a late Quaternary tank (natural reservoir) deposit from the Brazilian Intertropical Region

The Brazilian Intertropical Region (BIR) abounds with tank (natural reservoir) deposits, a primary source of late Quaternary megafauna remains. However, most of these important deposits lack comprehensive taphonomic analysis. In this study, we conducted a taphonomic analysis of Quaternary vertebrates from a specific tank deposit located at Fazenda Charco (Poço Redondo, Sergipe State), Brazil. We aimed to: (i) reconstruct the biostratinomic processes that influenced the deposition of vertebrate remains; (ii) interpret some fossildiagenetic features; and (iii) compare our findings with other tank deposits to highlight the main preservation patterns among these deposits. Additionally, we discuss the paleoenvironmental and paleoecological aspects of this vertebrate assemblage. The paleocommunity comprised eighteen individuals, including megamammals and reptiles, with a total of eleven taxa identified in the tank deposit, indicating a highly diversified assemblage. Eremotherium laurillardi and Toxodontinae indeterminate accounted for more than one individual each. Despite the high diversity, taphonomic features suggest the dominance of E. laurillardi in the assemblage and the preservation of bones transported from moderately distant locations to the tank deposit. Furthermore, Fazenda Charco exhibits a complex tank deposit characterized by various taphonomic signatures, including abrasion, trample marks, weathering, fragmentation, staining colors and bioerosions. These findings indicate that the bones underwent reworking events and were exposed to environmental conditions before their final burial. By integrating our taphonomic results with available isotopic, pollen, and speleothem data, we infer that a dry forest, resembling the extant Caatinga biome, prevailed during the past 42,000 years. This suggests a predominantly arid environment with a mosaic of phytophysiognomy dominated by herbs and shrubs. The further integration of taphonomic and paleoecological analyses of fossils from tank deposits will contribute to a more refined reconstruction of the paleoenvironmental scenario and the ecological interactions that occurred during the late Quaternary.

The paleoichnofauna in bones of Brazilian Quaternary cave deposits and the proposition of two new ichnotaxa

The Quaternary vertebrate paleontology of the Brazilian Intertropical Region is well-known, but there are only a few publications on bone ichnology. In this paper, we analyzed trace fossils in 23 bones of the Gruna das Três Cobras, Complexo Suíço, and F3 caves, which are located in Bahia and Rio Grande do Norte states, in the Brazilian Intertropical Region. We discovered gnaw marks assigned to Machichnus and bite marks attributed to Nihilichnus, as well as insect modifications referring to single (Cuniculichnus, Gunnellichnus, Karethraichnus, and Osteocallis) and multiple behaviors (Munitusichnus, and Taotieichnus). Additionally, we proposed the new ichnospecies Nihilichnus sulcatus n. isp. (bite mark) and Cuniculichnus cascudoi n. isp. (insect feeding mark). Regarding the predation/scavenger marks, Protocyon troglodytes was the probable primary modification agent, but some traces may also be attributed to Smilodon populator and Caiman latirostris. Cuniculichnus, Karethraichnus, Munitusichnus, and Osteocallis are attributed to dermestids, whereas termites probably produced Gunnelichnus and Taotieichnus.

A Tale of Two Continents (and a Few Islands): Ecology and Distribution of Late Pleistocene Sloths

Late Pleistocene sloths were widely distributed and present in a diversity of habitats in South, Central, and North America and some Caribbean Islands. Late Pleistocene sloths include 27 genera in four families Megatheriidae, Megalonychidae, Mylodontidae, and Nothrotheriidae. There is no consensus on the number of valid species. Some sloths have wide geographic distributions and are present on multiple continents while others have a much smaller distribution. Our knowledge of the paleoecology and natural history of the different sloths varies greatly depending on their relative abundance. The wide distribution of sloths and adaptations to different habitats results in several “sloth” faunas with different taxonomic compositions. These generalized faunas can be distinguished geographically as Temperate North America (five genera), Southern Mexico and Central America (five genera), Northern South America (two genera), West Coast of South America (four genera), the Andes and Altiplano (four genera), Brazilian Intertropical Region (nine genera), Pampas-Patagonia and the Caribbean Islands (Cuba, Hispaniola, and Puerto Rico, four genera). Some genera may occur in multiple regions but are represented by different species. These regions also have differences in other mammalian taxa, so the sloths are often in ecological competition with different megaherbivores or preyed on by different carnivores.

Inferences of the ecological habits of extinct giant sloths from the Brazilian Intertropical Region

ABSTRACTThree indices estimated from measurements of the humerus and ulna were used to suggest possible ecological habits of eight extinct giant sloths from the Late Pleistocene of the Brazilian Intertropical Region. To make these inferences, data from extant primates and xenarthras representing suspensory, climbing and digging forms were compared. The results indicate niche differentiation existed between these species; Ahytherium aureum, Australonyx aquae and Nothrotherium maquinense could have been climbers, Catonyx cuvieri, Ocnotherium giganteum and Glossotherium phoenesis were diggers, while Valgipes bucklandi and Eremotherium laurillardi were strictly terrestrial in their habits. These results suggest a general pattern in which members of the Megalonychidae and Nothotheriidae were mainly climbers, whereas mylodontines were mainly diggers, and scelidotheres were strictly terrestrial along with members of the giant Megatheriidae.

Interrelation of radiocarbon ages from bone fractions in the Brazilian Intertropical Region

AbstractThere is a consensus in the literature that radiocarbon dating performed on bioapatite often produces ages younger than dating performed on collagen. We propose a general regression that could be used to convert the bioapatite radiocarbon ages to the simulated ages on collagen in fossil samples worldwide. This general regression presents several good indices of quality, high correlation (R2 = 0.98), lower values of percent predicted error (%PE = 0.01), and standard error of the estimate (%SEE = 21.83), showing that it is a good tool, as the predicted values are similar to those observed. Using this regression, we converted the radiocarbon ages of bioapatite to the expected age from the collagen fraction made for several taxa from the Brazilian Intertropical Region (BIR) and suggest that these dates could be 1–7 cal ka BP older than previously thought.

Annual isotopic diet (δ13C) ofEremotherium laurillardi(Lund, 1842) and climate variation (δ18O) through the late Pleistocene in the Brazilian Intertropical Region

AbstractWe inferred the annual isotopic diet (δ13C) of an individual of the giant ground slothEremotherium laurillardifound in Toca dos Ossos (Ourolândia, Bahia, Brazil) through the extension of its third inferior molar. This individual lived in the region at 40,779–39,617cal yr BP. One year of its life was recorded in a length of 67 mm in the tooth. Two years were recorded in this molariform, during which the diet and climate did not change much, and substantial precipitation occurred during the middle of the year, which is in opposition to the modern pattern. The mean carbon (μδ13C = −13.9 ± 1.8‰) and oxygen (μδ18O = 22.5 ± 2.9‰) isotopic values were similar to values for other individuals of the species found in the same cave but different from the values found in other localities of the Brazilian Intertropical Region, which allows us to suggest that this region had more precipitation and lower temperatures in comparison to today. The oxygen isotopic values found in dated fossils ofE. laurillardiand from two other taxa found in the same cave (Toxodon platensis, andNotiomastodon platensis) could help in the understanding of the climatic variation that occurred in the region.

Trace fossils on megafaunal bone remains from Quaternary natural tank deposits of Brazil: A case study in João Cativo Paleontological site, Megafauna Valley, Brazil

Northeastern Brazilian natural tank deposits stand out among the sedimentary deposits bearing megafauna remains in South America. João Cativo Paleontological Site (JCPS, Itapipoca, Ceará State, Brazil) is included in the Megafauna Valley and is one of the main sources of paleoecological data in that area. This study reveals trace fossils detected on Quaternary megafauna remains recovered from JCPS, allowing interpretation of paleosynecological interactions among the Quaternary megafauna taxa of the Brazilian Intertropical Region (RIB) and associated taxa. Only four of the 951 fossil specimens (cranial, post-cranial, osteoderms, and teeth) collected in the 1960s had biogenic signatures related to predation/scavenging and pre-historic human handling. Scratches on two rib fragments and a metapodial of Eremotherium laurillardi are attributed to the ichnospecies Machichnus fatimae and suggest a feeding interaction between a canid (probably Protocyon troglodytes) and the carcass of E. laurillardi. The anthropic mark corresponds to incisions made by a lithic weapon in the femur of a Palaeolama major, likely with the intent of slicing and sawing the carcass into smaller pieces.

Seasonal variations in diet (δ13C) and climate (δ18O) inferred through toxodonts enamel teeth during the Late Pleistocene in the brazilian intertropical region

To access the annual isotopic variation of Toxodon platensis Owen, 1837, tooth enamel samples found in tanks in two localities in the Brazilian Intertropical Region (Puxinanã, Paraíba and Caruaru, Pernamuco) was analyzed isotopically (δ13C, δ18O). We suggest that one annual growth cycle of toxodonts could be represented by 11–17 mm of enamel. The carbon and oxygen isotopic values of the studied samples (LEG 2249–2253) are statistically different, interpreted as reflecting different climatic conditions in both localities. The interpretation of the carbon isotopic results shows little variation in the diet. The oxygen isotopic values of all samples represent the record of at least three years under different climate regimes. The carbon and oxygen isotopic values suggested that the feeding behaviour of these toxodonts were not influenced by the prevailing climatic conditions in both localities.

Inferring the paleoecology of the Late Pleistocene giant ground sloths from the Brazilian Intertropical Region

This paper provides diet interpretations for nine giant ground sloth species that lived in the Brazilian Intertropical Region, through the relative muzzle width technique and occlusal surface area (except Mylodonopsis ibseni). We propose that Eremotherium laurillardi, Ocnotherium giganteum, Mylodonopsis ibseni, Glossotherium phoenesis, Catonyx cuvieri, Valgipes bucklandi, Ahytherium aureum, and Australonyx aquae were adapted to had a mixed-feeder diet, having a great oral food processing, which could indicate an adaptation to need less from the fermentation on digestive tract, and similar, or even higher, metabolic requirements in comparison with ungulates of similar body mass. While, N. maquinense was adapted to a browser diet, and probably presented high fermetantion capability and low metabolic requirement, in comparison with all other giant ground sloth taxa.

Mammal Taphonomy in a Cave Deposit From Quaternary of Brazil

In Brazil, the Quaternary caves of the Brazilian Intertropical Region (BIR) host important fossiliferous deposits of terrestrial vertebrates, whose fossil content is taxonomically well known. Here, we conducted a taphonomic analysis based on macroscopic and microscopic features of 543 specimens collected in the F3 cave, a fossiliferous deposit located in the municipality of Baraúna, northeast of Brazil. This deposit encompasses 17 taxa, but it is dominated by fossils of Eremotherium laurillardi. Most bones were buried in less than a year, but the taphonomic history of this deposit was governed by alternation of dry and wet cycles. This led us to recognize four taphonomic modes, that differ according to the climatic conditions in which the bones were preserved as well as the time interval between the accumulation and the final burial of the remains.

Inferring the Paleoecology of the Late Pleistocene Giant Ground Sloths from the Brazilian Intertropical Region Through Relative Muzzle Width and Occlusal Surface Area

Inferring the Paleoecology of the Late Pleistocene Giant Ground Sloths from the Brazilian Intertropical Region Through Relative Muzzle Width and Occlusal Surface Area

Panthera onca (Linnaeus, 1758) from the late Pleistocene of Brazilian Intertropical Region: taxonomy, habitat, isotopic diet composition, and isotopic niche overlap with extinct faunivores

This paper focuses in the description, radiocarbon dating and isotopic analyses (δ13C, δ18O) of new fossils of Panthera onca from the late Pleistocene of the Brazilian Intertropical Region. This paper focuses on the paleoecology of this large cat and is of major importance to understand ecological niches in evolutionary time. Radiocarbon datings and stable isotope compositions (carbon and oxygen) were determined from the structural carbonate of enamel for two fossils of Panthera onca found in two caves in Bahia, Brazil. Isotopic data available of large faunivores and other extinct and extant herbivorous taxa from the late Pleistocene of the Brazilian Intertropical Region were used for paleoecological interpretations. Carbon and oxygen isotopic values from P. onca allow us to suggest that these individuals lived in arboreal savanna habitat between 26 and 33 kyr BP, could reach 209 kg and feed mainly on Nothrotherium maquinense, Tapirus terrestris and Alouatta sp., being a specialist. The isotopic niche overlap with Smilodon populator and Arctotherium wingei was high, while with Protocyon troglodytes was low. In the late Pleistocene P. onca probably suffer high ecological pressure by S. populator, while with A. wingei this could not occur, as this species could be mainly herbivorous.

Isotopic paleoecology (δ13C, δ18O) of two megamammals assemblages from the late pleistocene of Brazilian intertropical region

In the late Pleistocene of two localities of Brazilian Intertropical Region (one in Bahia state, and another in Piauí state) lived meso-megamammals herbivores belonging, at least, to three guilds: mixed-feeders (Eremotherium laurillardi, indetermined Equidae, Glyptotherium sp., and Holmesina paulacoutoi), grazers (Notiomastodon platensis, Glyptotherium sp., indetermined Cervidae, and Toxodon platensis) and omnivores (Pachyarmatherium brasiliense). The paleoecologial informations (datings, isotopic diet and niche breadth) were acquired through radiocarbon datings and ratio isotopic analysis of carbon (δ13C). The Notiomastodon platensis from Caetanos, Bahia presents a radiocarbon dating of 23,040 ± 55 14C years BP (25,604–25,203 Cal years BP) showing that it lived in the region in the late Pleistocene. We propose that Notiomastodon platensis (pi > 74%) and Glyptotherium sp. (pi > 76%) had preference for C4 plants, Equidae preferred to eat C3 plants (pi = 62%), while Cervidae and Toxodon platensis were specialists in C4 plants (pi = 100%). Eremotherium laurillardi had a genaralist diet, with preference for C3 plants in Piauí (pi = 66%), and in C4 plants in Bahia (pi = 68%). Holmesina paulacoutoi had a generalist diet, as well, prefering C4 plants (pi = 59%). Pachyarmatherium brasiliense was the unique omnivore in this study, and could explore savanna habitats, searching for food.The δ13O values in Caetanos, Bahia ranged from 27.2% to 29.5% and for São Raimundo Nonato, Piauí, from 29.5% to 32.7%. We suggest that the paleoenvironments in both localities was constitude by dry and open environments.

Presence of the ground sloth Valgipes bucklandi (Xenarthra, Folivora, Scelidotheriinae) in southern Uruguay during the Late Pleistocene: Ecological and biogeographical implications

Within the subfamily Scelidotheriinae, Valgipes bucklandi represents one of the least known taxa due to its scarce records and material found so far. This Pleistocene ground sloth had been registered only in Brazil, within the Brazilian Intertropical Region (BIR) in the states of Bahia, Minas Gerais, Piauí, Rio Grande do Norte and, more recently, outside the BIR, in Mato Grosso do Sul. A particular feature of this sloth is the proximal and distal fusion of the tibia and fibula in adults. Here, we report a tibia-fibula assigned to V. bucklandi found in Arroyo del Vizcaíno (Canelones, Uruguay), a fossiliferous site that harbors a large amount of megamammal remains at an approximate age of 30 ka (29696–32009 cal yr B.P.). We performed stable isotopes analyses and ecological niche models (ENM) to study V. bucklandi distribution and climatic and dietary preferences, as well as to better understand its presence ~2000 km southward of its previous recorded occurrences. δ13C values were consistent with those of the BIR, indicating a similar preference for C3 plants, while the results of δ18O values could be related to colder and more humid environments, clearly different from those obtained from BIR specimens. Furthermore, the ENM results also showed colder and more humid environments for the AdV record, with the occurrence being in the margins of the predicted potential distribution of the taxa. This discovery expands the distribution of this taxa to southern colder climates, indicating a greater climatic tolerance. Moreover, our results support the existence of mixed faunas composed of Southern and Northern taxa coexisting in Southern Uruguay at the onset of the Last Glacial Maximum, and provide evidence of the existence of an open mosaic habitat with patches of mixed vegetation in the region.

Annual isotopic diet (δ13C, δ18O) of Notiomastodon platensis (Ameghino, 1888) from Brazilian Intertropical Region

Notiomastodon platensis was an endemic South American proboscidean, which could reach about six tons and had a mixed feeder diet with predominance of C4 grasses in Brazilian Intertropical Region (BIR). In the last decades, its feeding behavior has been rebuilt mainly through dental calculus, enamel microwear and stable isotope analyses. However, all these techniques allow us to know only punctual information about its diet. In the present study we used stable isotopes (carbon and oxygen) in tusk fragments, allowing us to retrieve information about the six years of life for two individual specimens from Bahia state. The tusk fragment LGUESB 0002 was from an individual from Vitória da Conquista county, which lived at 17 ka BP and had a constant grazer diet in a stable climate environment. The other individual was from Coronel João Sá county that lived in the beginning of the Holocene at 9 ka BP, and presented a mixed feeder diet with consumption of C4 grass and C3 plants (pi = 40%), in an environment with high precipitation variation. This research presents the first annual series of isotopic composition for proboscidean tusks from BIR and the first evidence that the species lived in this region during the Holocene.