Late Pleistocene carnivores (Carnivora: Mammalia) from a cave sedimentary deposit in northern Brazil

The Brazilian Quaternary terrestrial Carnivora are represented by the following families: Canidae, Felidae, Ursidae, Procyonidae Mephitidae and Mustelidae. Their recent evolutionary history in South America is associated with the uplift of the Panamanian Isthmus, and which enabled the Great American Biotic Interchange (GABI). Here we present new fossil records of Carnivora found in a cave in Aurora do Tocantins, Tocantins, northern Brazil. A stratigraphical controlled collection in the sedimentary deposit of the studied cave revealed a fossiliferous level where the following Carnivora taxa were present: Panthera onca, Leopardus sp ., Galictis cuja, Procyon cancrivorus, Nasua nasua and Arctotherium wingei . Dating by Electron Spinning Resonance indicates that this assemblage was deposited during the Last Glacial Maximum (LGM), at least, 22.000 YBP. The weasel, G. cuja , is currently reported much further south than the record presented here. This may suggest that the environment around the cave was relatively drier during the LGM, with more open vegetation, and more moderate temperatures than the current Brazilian Cerrado.


INTRODUCTION
The Brazilian Quaternary fossil deposits are mainly represented by karstic caves (Auler et al. 2003). The first studies of fossil mammals found in caves of South America were conducted from 1837 to 1844 by Peter Lund in Lagoa Santa, state of Minas Gerais, southeastern Brazil (Marchesotti 2011). As part of his research, Lund described the first fossil records of Carnivora from Brazil.

REGIONAL AND GEOLOGICAL SETTINGS
The fossils described here were collected in 2011, 2012 and 2013 in a limestone cave named "Gruta do Urso", at Aurora do Tocantins (-12,583; -46,516), state of Tocantins, northern Brazil. The geology of the studied area is still poorly understood. Online notes of Companhia de Pesquisa de Recursos Minerais (CPRM) report on the studied region, carbonate and terrigenous deposits of the Bambuí Group.
The excavation inside the cave was controlled in order to identify the stratigraphy of the deposit. Three stratigraphic levels were recognized: 1-A superficial carbonated layer that cements the top of the cave deposit; 2-A laminated reddish-grey loess-like sediment with granulometry from very thin to thin, with a thickness of 180 to 220 millimeters. Only the second layer (level 2) contained fóssil remains. 3-A yellowish layer of thicker granulometry and containing several detached angular clasts that originated from the cave walls. This third level presents a thickness of 500 mm but it may vary according to the different sections of the cave.

MATERIALS AND METHODS
The material was identified by direct comparisons with specimens housed in the following collections: Museu Nacional/Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil (MN/UFRJ); Museu de Ciências Naturais of the Pontifícia Universidade Católica de Minas Gerais, Minas Gerais, Brazil (PUC Minas); Museo de La Plata, Universidad Nacional de La Plata, La Plata, Argentina (MLP); and Museo Argentino de Ciencias Naturales ''Bernardino Rivadavia", Buenos Aires, Argentina (MACN). The identification was also based on descriptions found in the literature (Berman 1994, Seymour 1989, Yensen and Tarifa 2003. The information on the geographical distribution of extant species was based on Wilson and Mittermeier (2009).
Electron Spinning Resonance (ESR) dating was performed on the specimen UNIRIO-PM 1027 (specimen L4) by the Physics Department of the Universidade de São Paulo (FFCLRP-USP; www. ffclrp.usp.br/departamentos/fisica). We chose to date only one specimen due to the fact that all carnivores were recovered from the same level (level 2). Therefore, this specimen is considered to be synchronic with the remaining specimens described here.

RESULTS
A total of 25 specimens, described hereafter, were identified within five families and six species of Carnivora (Table I).
Fossil record in South America. The first findings of P. onca in South America are from the Ensenadan (early to middle Pleistocene) at "Toscas del Río de La Plata", Buenos Aires, Buenos Aires Province (Berman 1994 although discussed by  Soibelzon et al. 2008 Upper third incisor (I3) -UNIRIO-PM1029 is a right upper incisor, with little wear on the crown apex, and laterally compressed roots. Both specimens are similar in size, but UNIRIO-PM 1032 is smaller. The right I3 UNIRIO-PM 1043 is the largest specimen among the material. Its crown is much worn with only a small band of enamel left, and the root is slender towards its apex. The tooth is compressed mesiodistally, and resembles a canine for having a conical main cusp. The labial side of the tooth is convex and the lingual side is slightly concave. On the lingual side, there is a narrow enamel crest that extends mesio-distally from the base of the crown to the apex of the main cusp; at this point a cusplet is developed. The distal side is straight and has a small groove where the lower canine occludes.
Upper canine (C) -The upper right canine UNIRIO-PM 1053 has moderate wear on its crown apex. The tooth is also fragmented at several parts of its crown and root. The other tooth, an upper left canine, UNIRIO-PM 1054, presents cracks on the root and on the upper half of the crown.
Maxillary bone -UNIRIO-PM 1027 is a left fragment of maxillary bone bearing the P2 and the P3. The P3 has two main cusps, where the mesial cusp is larger than the distal cusp. At the center of the base of the mesial cusp there is a small cusplet. The distal border of the crown ends with a transverse enamel ridge. The P2 is the smallest upper premolar and it is more developed mesiodistaly than labiolingualy, which forms a round shape. In occlusal view there is an enamel bridge.
Upper fourth premolar (P4) -The left P4 UNIRIO-PM 1031 is well preserved, and has a small fragment of maxillary bone preserved on its labial and lingual portions. The specimen UNIRIO-PM 1026 is Description. Upper second incisor (I2) -UNIRIO-PM 1028 is well preserved, however, it was not possible to distinguish it as left or right because of the similar morphology between right and left tooth. This tooth is larger than the upper fi rst incisor. The root is mesiodistally compressed along its length. The crown extends laterally forming a a left P4, also well preserved, but with some cracks on the root. The tooth has three roots, and the distal one is labio-lingually compressed and comprises the length of the metacone and half of the paracone. The mesiolabial root is positioned below the parastyle, lingually compressed and diagonally positioned. The third root is mesiolingually positioned below the protocone. The apex of this root bends towards the labial side. There are three cusps aligned at the labial border. The mesial cusp, the parastyle, is the smallest; the central cusp, the paracone, is the largest one followed by the distal cusp, the metacone. There is a shearing facet along the apex of all three cusps. The parastyle is conical, and the paracone is taller than the other two cusps being labiolingually compressed. The labial side of the paracone is convex and the lingual is flat. The labial portion of the metacone is also flat. The metacone presents a convex surface on the labial portion. The protocone is the smallest cusp, has round shape, and presents a punctiform projection at the apex which is positioned in front of the junction between the parastyle and the paracone.
Mandible -UNIRIO-PM 1025 is a right fragment of mandible with well preserved p3 and p4. The mandible is broken between the distal part of the p4 and the proximal portion of the mentonian foramen. Both teeth have similar morphology but the p4 is larger than the p3. On both teeth there is a main cusp which is bigger than the other ones, plus other two accessory cups. The distal accessory cusp is smaller than the mesial one. On both teeth there is also a large cingulum in distal portion.
Indet. canine -UNIRIO-PM 1056 is a well preserved root having only the crown's base. It was not possible to identify this canine as superior or inferior nor right or left. UNIRIO-PM 1055 is a worn root, which was also not possible to identify any further.
Remarks. UNIRIO-PM 1025, 1027, 1031, 1047, 1053, 1054, 1055 and 1056 were all found associated in the sediment. Puma is the most similar taxon to Panthera in size and morphology.
The canines of Pa. onca are markedly developed and robust. As in Puma concolor, the protocone of the P4 is placed on the lingual side of the crown (in front of the paracone-metacone boundary), but in Pa. onca the protocone of the P4 is proportionally larger and much more separated from the other two cusps. Also, the P4's parastyle is larger in Pa. onca in comparison to Pu. concolor. The p3 has a much more developed posterior cingulum in Pa. onca. Unlike Pa. onca, the P4 in Pa. leo has a cingulum around the parastyle. The p4 crown is much lower in Pa. onca than in Pa. leo which has an elongated principal cusp. The parastyle in P4 is less developed in Pa. onca than in Smilodon.
In Smilodon all cusps are queued and mesiolabial cusps are absent. The upper canine of Smilodon is clearly broader and longer that the C1 of Pa. onca. Moreover, the canines of Smilodon are serrated on its lingual portion and comprised on its mesiodistal portion.
Description. Upper fourth premolar (P4) -The left P4 UNIRIO-PM 1048 is broken on the parastyle and protocone and also has missing roots. The paracone is triangular and higher than the metacone. The apex of the metacone is almost straight. The base of the crown in labial view goes up towards the end of the metacone. The labial portion is concave and folds to the inside where the metacone connects the paracone.
Description. Upper third incisor (I3) -The right I3 UNIRIO-PM 1033 is well preserved and has a deep groove where the tooth occludes with the lower tooth. The tooth is labio-lingually compressed from the root apex to halfway up the crown. The crown has a large central cusp, conically shaped on its base and mesiodistally curved. The crown is convex on labial view, straight on distal view, and concave on mesiolingual view.
Upper incisor indet. -UNIRIO-PM 1060 has the root broken on its apex. The crown is well preserved with little wear. The root is mesiodistally compressed, and larger on the mesial and distal view than on the lingual and labial view. The crown has a triangular form in all views. There is a groove on the occlusal area.
Upper canine (C) -The right canine UNIRIO-PM 1021 is well preserved, having few cracks and little wear on the crown. It is a large tooth in both length and width. The crown is conical and slightly labiolingually compressed, and delimited by two enamel crests that are present along the whole length of the crown. The root is long, laterally compressed and gets thinner towards its apex. The mesial part of the root is concave and the distal part is convex.
Lower canine (c) -The left canine UNIRIO-PM 1020 is shorter and thinner than its upper correspondent. The crown has little wear and some cracks are present along the whole tooth. The root is bent and longer than the crown. The crown is also bent and has the same crests as the upper canine.
Remarks. All specimens belong to one individual adult specimen. UNIRIO-PM 1020 and UNIRIO-PM 1021 were found associated, and are proportional in size. The occlusion is also perfect between them. A. wingei is the only species known for the late Pleistocene of northern South America (Brazil, Bolivia and Venezuela). The exception is the record of A. tarijense to Tarija, Bolivia, in sediments presumed to be younger than early Pleistocene (see Soibelzon et al. 2005, Soibelzon andRincón 2007). A. wingei is the smallest species of Arctotherium and even though size is not considered a good taxonomic character for bears, the difference between A. wingei and the other species is so conspicuous (Soibelzon and Tarantini 2009) that we decided to use it in association with other anatomical characters described in the next segment.
The canines of A. wingei are markedly curved labio-lingually. The upper canine is very similar between species of Arctotherium, differing mainly in size. The canine of A. wingei is the smallest among the species. The lower canine of A. wingei presents two enamel ridges as in A. angustidens and A. tarijense, while in A. vetustum and A. bonariense there are three ridges. The upper third incisor is the largerst incisor of the upper tooth row; it is caniniform, with a high laterally compressed crown. The main cusp is morphologically similar to that of the I2, the mesial ridge is broader and longer than the distal ridge, and there is no enamel bulge between them. In A. vetustum, the distal ridge is very small and the mesial ridge is small, while in A. angustidens and A. tarijense both ridges are large. The total of observed characters leads us to assign the following specimens as A. wingei.  Table I) New material. UNIRIO-PM 1001 is represented by a right and a left dentary. On the right dentary the coronoid and condylar processes are absent. Only the p4 and m1 are present, and only the alveoli of the incisors, canine, p3 and m2 are preserved. The left dentary has i3, c, p2, p3, p4, m1 and m2 present and no tooth is worn.
Fossil record in South America. The species is recorded from late Pleistocene to early Holocene Description. Dentaries -UNIRIO-PM 1001 left dentary has its angular process preserved but the coronoid and condylar processes are broken. The labial portion is broken at the same height as the p4. The material has cracks all over its surface. The mandibular foramen is preserved. The right dentary is broken horizontally at the coronoid process. The fracture was made during the collection of the material, but it was possible to reunite and glue all parts. The angular portion of the condylar process is broken on its lingual portion. Five mentalis foramina and the mandibular foramen are present.
Third lower incisor (i3) -The crown is straight and quadrangular on labial view.
Lower canine (c) -The base of the crown is large and gets thinner towards its apex. The tooth is curved, where the labial portion is convex and the lingual portion is concave.
Third lower premolar (p3) -There is only one conical cusp. A thick cingulum is present in front of the mesial margin of the p4.
Fourth lower premolar (p4) -This tooth is bigger than the p3 but it is very similar in form to the p3. The enamel is elongated behind the single cusp, flexing markedly at the lingual margin of the tooth, while the labial margin is straight. The tooth is placed diagonally on the tooth row.

First lower molar (m1) -The protoconid is
straight. There is a thick cingulum at the talonid margin. The metaconid is absent.
Second lower molar (m2) -This molar is smaller than the m1, subcircular in form and has an enamel crest along the crown. The tooth is placed on the tooth row higher than the other teeth, next to the coronoid process.
Remarks. The genus Galictis is found throughout zoological collections with identifications that have been switched back and forth between G. cuja and G. vittata. The only dental characteristic that distinguishes G. cuja and G. vittata is the presence of a metaconid on the m1 of G. vittata. Apart from that, both species are very similar, except in size, where G. cuja is smaller than G. vittata. Both hemimandibles described here were found at approximately the same place in the cave, but in two different years. These dentaries have similar proportions and their symphyses are well preserved so that they fit together. Therefore, we consider that these dentaries belong to the same individual.
Description. Lower second molar (m2) -The right m2 UNIRIO-PM 1007 is markedly worn and it probably belonged to an older individual. The mesiodistal length is bigger than the labiolingual length. The distal edge is narrow and triangular. The mesial edge is broad and rounded. The trigonid and the talonid have similar dimensions. The metaconid and the hypoconid are absent and it is only possible to identify their bases. The base of the protoconid is almost the same length of the trigonid. The base of the metaconid is about half the size of the base of the protoconid. The base of the hypoconid is similar in length to the base of the protoconid, and is placed behind the mesiodistal portion of the tooth, aligned to the main axis. The entoconid is placed parallel to the mesiodistal portion of the base of the hypoconid. A cristid connects diagonally the base of the hypoconid and the entoconid. The mesial root and part of the enamel on the base of the crown are absent. The material has some cracks on both crown and root.
Remarks. The specimen of Procyon cancrivorus described here represents the first potential late Pleistocene record of the species to Brazil (for more details see Rodriguez et al. 2013).
Fossil record in South America. The species is recorded at the late Pleistocene of Tarija, Bolivia (Berta and Marshall 1978); late Pleistocene-Holocene of Minas Gerais, Brazil (Paula Couto 1970) and Bahia, Brazil (Cartelle 1999).
Description. Upper first molar (M1) -Three roots are present: two thin roots on labial position, which are mesiodistally compressed, and one large root of pyramidal form on lingual position. The crown is quadrangular, and longer labiolingually than mesiodistally. There are four cusps of pyramidal form. The paracone is the largest cusp placed at the mesiolabial portion of the crown. This cusp is connected with the metacone and the protocone by a thin enamel crest. The metacone is placed at the distolingual portion of the crown.
Remarks. Usually the M1 has a more rounded outlined crown than the material described here, which has a quadrangular outlined crown. A more rounded outlined crown was also observed in the specimens MNRJ 3075, MNRJ 13518 and MNRJ 32431 housed at the Department of Mammalogy of the Museu Nacional/Universidade Federal do Rio de Janeiro, Brazil. Also, the tooth is worn on the labial portion of the crown. Maybe this wear was caused by friction with upper teeth and/or bad occlusion. Bassaricyon gabbii has only one lingual cusp on the M1. Bassariscus astutus and Bassariscus sumichrasti have differences in form, number of cusps and form of these cusps, and resembles the M1 of Canidae. In Procyon cancrivorus the metacone is more centralized than in Nasua nasua, and presents a large mesiolabial cingulum that is not present in N. nasua. On the described material, the M2 is the tooth more similar with Pr. Lotor. However, some differences are recognizable between both taxa, such as lingual cusp larger and more centralized in Pr. lotor than in N. nasua. An other important difference is the presence of two accessory cusps in N. nasua. Also, the M1 of Pr. lotor has a lingual cingulum that is not present in N. nasua.
Description. Mandible fragment -UNIRIO-PM 1321 is broken behind the mentonian foramen. The mandibular symphysis is long and goes from the incisors to the p2 alveoli. On the mesial portion of the mandible the alveoli of the incisors are also broken. The canine is the only preserved tooth. Its crown is conical and curved towards the distal portion of the tooth. There are two enamel crests, one on the lingual portion and another on the mesial portion, which occludes with the upper third incisive. The crown is fissured perpendicularly to the mandible.
Remarks. The specimen was compared with Lycalopex vetulus, Lycalopex gymnocercus and Cerdocyon thous, due to the dental morphology similarity of these species to our material. The intraspecific variation and similarity of teeth between Canidae taxa have prevented us to identify our specimen beyond family level.

DISCUSSION
The fossil assemblage of "Gruta do Urso" cave includes the greatest diversity of Pleistocene Carnivora found in association at the same site in South America (Table I). The stratigraphic control applied, assured that all fossils came from the same level. Therefore, this assemblage can be recognized as part of an ancient mammalian community.
Previous studies in Brazilian caves gathered fossil diversity data from a number of caves or merged information from several localities (e.g. Cartelle 1999, Lessa et al. 1998) treating this collection of taxa of different spatial origins as a single ancient ecological community. Moreover, most fossils were found laying over the sediment (out of stratigraphic context), or no stratigraphic control was made during the excavation. In addition, there is also no taphonomic analysis nor numerical dating procedures in those previous studies to assure that all specimens were from the same locality and stratigraphic level. Therefore, these collections might represent artificial assemblages as a result of great temporal and spatial mixture. Although only one dating was performed on the fossils here described, the stratigraphic controlled survey performed at "Gruta do Urso" cave indicates that this assemblage has so far the highest Carnivora diversity for the late Pleistocene of South America.
Nowadays, South America is the continent which has the highest diversity of extant Carnivora (Van Valkenburgh 1988), but during the Pleistocene this diversity was even greater. Many of the South American extant taxa were already present in the continent during the late Pleistocene, and coexisted with species that became extinct during the late Pleistocene-Holocene boundary (Prevosti and Soibelzon 2012). Therefore, several extant South American carnivores are survivors of the late Pleistocene/Holocene extinctions. The conditions that allowed the survival of those taxa are still unknown, mainly because their fossil records are scarce. However, it appears to be partially related to their medium to small body masses.
Among the extant carnivores which are also recorded to the South American Pleistocene, the best known species from biostratigraphic context and geographic distribution is Panthera onca. Today, Pa. onca is also the largest living South American carnivore. Yet, large Pleistocene extinct carnivores such as Arctotherium, Smilodon and several taxa of Canidae are also well documented on the fossil record (Soibelzon and Prevosti 2007). The lack of information regarding the fossil record of middle to small-sized Pleistocene Carnivora of South America might lead to the idea of rarity. However, the common usage of survey techniques such as picking that evidence larger fossils (complete or fragmented) may help to support the assumption that smaller carnivore taxa were scarce. Furthermore, this scarcity of middle to small-sized Carnivora in South American Pleistocene deposits can be also a consequence of taphonomic bias (Soibelzon and Prevosti 2007). This would also explain their absence or scarcity in tropical regions (Soibelzon and Prevosti 2007).
Among the Carnivora taxa of Aurora do Tocantins, Arctotherium wingei is the only species that was completely extinct by the late Pleistocene (Soibelzon and Rincón 2007). This is the smallest (Soibelzon and Tartarini 2007) and the most herbivore (Figueirido and Soibelzon 2009) species of Arctotherium. The fossil record presented here represents the first fossil of A. wingei from Brazil with accurate stratigraphic procedure, since older findings (e.g. the materials from Minas Gerais) were described without stratigraphic context (see Soibelzon et al. 2005).
The described remains of Galictis cuja correspond to the first record of this species to northern Brazil, as well as the first record at lower latitudes of South America. The mustelid G. cuja is currently distributed from southern Peru to Argentina, except for southern Patagonia (Fig.  4a). Nowadays, Galictis cuja inhabits the drier Cerrado (Savanna) and Caatinga (Deserts and Xeric Shrublands) biomes of northeast Brazil, the Atlantic Forest throughout the eastern seaboard, and the pampas grassland towards the south (Bornholdt 2012). Therefore, it is possible that the extinction of G. cuja in northern Brazil was the result of environmental changes occurred during the end of Pleistocene.
The felid Panthera onca, and the procyonids Procyon cancrivorus and Nasua nasua are present today throughout all Brazilian territory, but the fossil records of the last two are more infrequent. These species may inhabit several habitats, such as dry and wet rainforests. They are common in gallery forests and areas close to freshwater, such as swamps, margins of rivers and mangroves (Handley 1976, Schaller 1983, Mondolfi 1986, Emmons 1990. Today, the jaguar Pa. onca is occasionally found in arid environments, but always nearby water sources (Wilson and Mittermeier 2009). It seems that the ability of Pa. onca to inhabit arid places is not that uncommon, since they occur in arid regions of Mexico and southwestern North America today. Also, late Pleistocene fossil records of jaguars indicate environmental plasticity across much of North and South America. Thus, their current geographic distribution is not necessarily a reflection of their potential range. Other fossils found in "Gruta do Urso" cave are also known for their association to freshwater resources: the sigmodontid rodent Holochilus sciureus (Pardiñas et al. 2011); the boiid snake Eunectes murinus (the anaconda; Hsiou et al. 2013); and the caiman from the subfamily Caimaninae. Although Pa. onca and Pr. cancrivorus currently occur on the studied area, this does not imply that the region was climatically stable since the Pleistocene. Although these species exhibit great environmental plasticity, we can only infer that their presence in the area during the time of deposition indicates freshwater sources nearby the caves.
Hence, the fossil assemblage recovered from "Gruta do Urso" cave indicates that the different climatic conditions and ecosystems might have existed during the late Pleistocene. Those changes probably produced the local extinction of G. cuja and the extinction of A. wingei.

ACKNOWLEDGMENTS
We would like to thank the following curators: João Alves and Sergio Maia Vaz (Museu Nacional-UFRJ), Castor Cartelle (