Hemiauchenia, Gervais & Ameghino, 1880

Hemiauchenia cf. H. paradoxa .

( Fig. 4C View Fig 1–G View Fig 2 View Fig ).

Referred material

Two fragments of right hemimandibles with deciduous dentitions ( PIMUZ A/ V 4186), right hemimandible body with m1–m3 partially preserved and left hemimandible body with dp4–m2 partially preserved ( PIMUZ A/ V 4187), right hemimandible with p3–p4 ( PIMUZ A/ V 4192), left hemimandible body with talonid of m2 and the entire m3 ( PIMUZ A/ V 4195), right hemimandible body with m2–m3 partially preserved ( PIMUZ A/ V 4201), two fragments of right and left hemimandibles with deciduous and permanent dentitions ( PIMUZ A/ V 4200), right hemimandible body with m1–m3 ( PIMUZ A/ V 4257), isolated m2 ( PIMUZ A/ V 4127, PIMUZ A/ V 4179, A/ V 4189), and isolated lower teeth ( PIMUZ A/ V 4196, PIMUZ A/ V 4255). Geographic data of the specimens are provided in Additional file 1.

Description and comparisons

PIMUZ A/V 4186 corresponds to two rights hemimandibles with dp4 without wear and erupting m1. Te dp4 is similar to teeth of the molariform series with three lobes.

Te cusps are still separated and have no wear. Te fossetids are mesiodistally opened ( Fig. 4C View Fig 1 View Fig ). PIMUZ A/V 4187 is represented by two fragments of a mandible probably from the same individual. Te right hemimandible has the talonid of the m1–m3 partially preserved ( Fig. 4D View Fig 1– D View Fig 2 View Fig ). Te left hemimandible has a dp4 and both trigonids of m1–m2 fractured and cover by carbonate concretions. In this specimen the molars have all fossae closed and labial lophids with U-shaped. Left dp4 is similar to the molariform series, with three lobes. Right m3 shows the characteristic “Llama buttresses”. PIMUZ A/V 4192 is a fragment of right hemimandible body with the p3–p4 series ( Fig. 4E View Fig 1–E View Fig 2 View Fig ). Te p3 is transversely compressed and formed by only one lobe; this tooth lacks wear. Te p4, with slight wear, has a flexid on both, the labial and lingual sides, defining two lobes. Te mesial lobe is mesiodistally elongated, and the distal one is transversely wide.

PIMUZ A/V 4195 is the left hemimandible body with the talonid of m2 and a m3 ( Fig. 4G View Fig 1–G View Fig 2 View Fig ). Te fossae of both molars are closed and the stylids on m3 are developed. Te hypoconulid is smaller and oval and lack a fossa. PIMUZ A/V 4200 represents a right and left fragment of hemimandibles with teeth. Te right series has the roots of m1 and complete m2–m3. Te m3 lacks wear, lacks a hypoconulid, and has a small protostylid, and both fossetids are mesiodistally opened. Te left series has dp4–m2. PIMUZ A/V 4201 is a fragment of the right hemimandible preserving the talonid of the m 2 in advanced wear stage and the entire m3. No mesial stylids are observed in the m3, while the hypoconulid is smaller and oval in outline, lacking a fossa. PIMUZ A/V 4179, and PIMUZ A/V 4189, 4127, are isolated m2, the first is left, and the second and third are right. Teeth have different wear stages, closed fossae, and developed mesial stylids. PIMUZ A/V 4179 shows a “wear stage 1” with its fossetids lingually opened, suggesting this specimen to be of a young camelid ( Breyer, 1977). PIMUZ A/V 4255 corresponds to m1, m2 and m3. Teeth do not preserve roots. PIMUZ A/V 4196 is represented by a left permanent p4 and probably a p3, m1 and m2. Tese teeth are similar to the molariform series previously mentioned in H. paradoxa (PIMUZ A/V 4287; see above). PIMUZ A/V 4257 is a right hemimandible with m1–m3 ( Fig. 4F View Fig 1–F View Fig 2 View Fig ). Te teeth have fossae closed, although fossetids on m3 are erupted and mesiodistally opened. Lingual stylid (protostylid) is presented in all molars and is lingually well developed, while the parastylid is only preserved on m1 and being more evident in the m2 ( Fig. 4F View Fig 1 View Fig ).

Remarks

No diagnostic characters have been observed in the lower deciduous teeth of South American camelids (e.g., Cabrera, 1932, 1935; Rusconi, 1931; Webb, 1974). Te specimens referred above are tentatively attributed to Hemiauchenia cf. H. paradoxa , because they have a similar size and similar dental morphology as shown by H. paradox a from Pleistocene deposits of Argentina and Brazil ( Scherer et al., 2007; Vezzosi et al., 2019).

cf. Hemiauchenia sp.

( Fig. 5A View Fig 1–E View Fig 2 View Fig ).

Referred material

Isolated molars likely M1? or M2? (PIMUZ A/V 4098, 4103, 4180, 4181, 4182). Geographic data of the specimens are provided in Additional file 1.

Description and comparisons

Te material is represented by four left (PIMUZ A/V 4103, 4180, 4182), and one right (PIMUZ A/V 4181) likely M1 or M2, characterized by different wear stages

( Fig. 5A View Fig 1–E View Fig 2 View Fig ). Te mesial lobe is larger than the distal one, with very large stylids (metastyle, parastyle and mesostyle), and with a deeper fossa of the trigon.

Remarks

Tese molars have a size similar to those of Hemiauchenia ( Cabrera, 1935; Scherer et al., 2007) and with U-shaped lingual lophs differing from those in the teeth of Palaeolama major which are V-shaped (see Scherer et al., 2007; Webb, 1974). According to a study based on North American specimens, the shape of the lophs is a generic difference between Hemiauchenia and Palaeolama ( Webb, 1974) . Larger samples of South American camelids are needed to test this generic difference among others dental characteristics observed in the upper dentitions.

Camelidae indet.

( Fig. 5F View Fig 1–O View Fig 2 View Fig ).

Referred material

Te remains include four lower incisors, fragment of maxilla and right hemimandible, both with dentition (PIMUZ A/V 4253), badly preserved skull, mandible and dentition of a young camelid (PIMUZ A/V 4286), fragment of a mandible and both premaxilla (PIMUZ A/V 4256), 75 isolated molariforms (PIMUZ A/V 4254), and isolated and fragmentary hemimandible, symphysial bone and six incisors and molariform teeth (PIMUZ A/V s/n and no geographic context; see Additional file 1). Postcranial remains include a left eroded metacarpal (PIMUZ A/V 4250), distal end of left tibia with astragalus, navicular and cuboid (PIMUZ A/V 4090), right radius-ulna and right metacarpal, probably from the same individual (PIMUZ A/V 5969), three eroded astragali, a navicular and a podial phalanx (PIMUZ A/V 4208). Geographic data of the specimens are provided in Additional file 1.

Description and comparisons

Te left fragment of maxilla of PIMUZ A/V 4253 has the M1–M3 series with the M1 completely covered by carbonate concretions. Te lower dentition has right i1– i2 and left i1–i2 (this last incisor is isolated) ( Fig. 5G View Fig ). Te right hemimandible body has the distal root of p4 and m1–m2 out of their sockets, while m3 is in eruption ( Fig. 5I View Fig 1–I View Fig 2 View Fig ). All molars have similar size to that of a large camelid, although the occlusal surfaces are fractured or covered by carbonates that make them inaccessible for comparisons. Te skull PIMUZ A/V 4286 presents a morphology and dimensions of a small camelid as Lama . However, the carbonates adhered to this specimen make impossible to recognize diagnostic features. Te maxilla and the mandible in this specimen do not present diagnostic elements for a generic assignment. PIMUZ A/V 4254 is represented by numerous upper and lower teeth (N° 75) of different sizes attributed to Camelidae , and its state of preservation does not allow more accurate determinations. Te left metacarpals III and IV under the number PIMUZ A/V 4250 ( Fig. 5J View Fig ) are fused to each other, except at the distal end, as is seen in camelids. PIMUZ A/V 4090 is represented by a distal end of left tibia articulated with astragalus, navicular, and cuboid; the covering by carbonates ( Fig. 5M View Fig ) impedes an assignment beyond the family level. PIMUZ A/V 5969 is a partially damaged right radius-ulna ( Fig. 5L View Fig ), and right metacarpal ( Fig. 5K View Fig ). PIMUZ A/V 4208 is represented by three eroded astragali ( Fig. 5N View Fig 1–O View Fig 2 View Fig ), a navicular and a podial phalanx. Two of three astragali resemble in size that of a small camelid, such as Lama guanicoe , while the larger has a morphology and size that resembles Hemiauchenia ( Scherer et al., 2007) . Both navicular and podial phalanx do not allow a more precise determination.

Remarks

A specific assignation of the above specimen is not possible due to its poor preservation and/or lack of diagnostic characters.

Tayassuidae Palmer, 1897

Tayassu Fischer von Waldheim, 1814

Tayassu pecari ( Link, 1795) .

( Fig. 6A View Fig 1–A View Fig 2 View Fig ).

Referred material

Left hemimandible fragment with the root of m2 and m3 mostly complete (PIMUZ A/V 4188). Geographic data of the specimens are provided in Additional file 1.

Description and comparisons

PIMUZ A/V 4188 is a fragment of the left hemimandible with the last root of m2 and a m3 mostly complete. Te tooth is brachydont and bunodont, preserving three main sharp cusps with slight wear: metaconid mesially, separated by a valley from the hypoconid, and entoconid distally ( Fig. 6A View Fig 1 View Fig ). Te molar is broken at the level of the protoconid and consequently we were unable to check the presence of a crenulated cingulid (e.g., Gasparini, 2007). Te first pair of anterior cusps (metaconid and protoconid) are partially broken, although both together are slightly wider than the posterior pair (hypoconid and entoconid), which is well preserved ( Fig. 6A View Fig 1 View Fig ). Behind both lobes, there is a third lobe with complex configuration in which four cusps with different size are seen, as in Tayassu pecari (see Gasparini, 2007; Parisi Dutra et al., 2017). Following Gasparini (2007) and Parisi Dutra et al. (2017), PIMUZ A/V 4188 falls in the size range of T. pecari , with a mesio-distal length of 22 mm and a linguolabial width of 12 mm. Tis m3 is elongated mesiodistally, with subrectangular outline due to the presence of the third cuspidate lobe that forms distally a complex hypoconulid ( Frailey & Campbell, 2012).

Remarks

Following Gasparini (2007) and Parisi Dutra et al. (2017), the configuration of the m3 reported here is clearly different from that of Brasilochoerus spp., Parachoerus wagneri , Tayassu tajacu , and Platygonus spp. (with the exception of Platygonus chapadmalensis ), because these tayassuids have a simple third lobe (with an unique dominant cusp; see Gasparini, 2007), sometimes accompanied by a pair of smaller cusps ( Frailey & Campbell, 2012; Gasparini & Ferrero, 2010).

Tayassuidae is among the earliest groups of mammals that entered South America during the GABI (Woodburne, 2010). Teir extensive fossil record is associated with Late Cenozoic deposits in Argentina, Brazil, Uruguay, Bolivia, Colombia, Peru and Venezuela ( Gasparini, 2013; Montellano-Ballesteros et al., 2014; Parisi Dutra et al., 2017, and references therein). Te exact moment of its first arrival is controversial, with estimated dates ranging between about 3.7 and 3.1 Ma (see Cione et al., 2007, 2015; Woodburne, 2010). According to the fossil record, the diversity and abundance of tayassuids in South America are greater during the Pleistocene than Pliocene and Holocene ( Gasparini, 2013). Moreover, the larger diversity and abundance of fossil species of tayassuids in South America is concentrated in Argentina ( Gasparini, 2013), where, according to Gasparini (2007), three genera with twelve species of Tayassuidae were recognized. Peccaries experienced a remarkable decrease in diversity near the Pleistocene–Holocene boundary ( Gasparini, 2013), and only two genera ( Parachoerus and Tayassu ) and three species are living today ( Gasparini, 2013; Parisi Dutra et al., 2017). Among these, the white-lipped peccary Tayassu pecari is widely distributed across the Neotropical region, from northern Argentina to southeastern Mexico ( Bustos et al., 2019; Gasparini et al., 2014). Despite its large range of distribution and fossil record in South America ( Gasparini, 2013; Montellano-Ballesteros et al., 2014), its past occurrence is scarce and restricted to the Middle Pleistocene– Holocene of the Buenos Aires, Corrientes, Misiones, Santa Fe, and Santiago del Estero ( Gasparini, 2013; Gasparini et al., 2014). Some morphological features in T. pecari are likely associated with the humid climate conditions and woodland environments that they inhabited ( Gasparini et al., 2014). However, Tayassu pecari occupied an extensive geographic range and must have had wide ecological tolerances, making it difficult to predict the habitats where it lived ( Parisi Dutra et al., 2017; Bustos et al., 2019).

Tayassuidae indet.

( Fig. 6B View Fig 1–B View Fig 2 View Fig ).

Referred material

Left/right? dp4 with at least two lobes (PIMUZ A/V 5258). Geographic data of the specimens are provided in Additional file 1.

Description and comparisons

PIMUZ A/V 5258 is a deciduous bunodont and brachydont dp4, with advanced wear of the occlusal surfaces of their lobes, indicating that the specimen belongs to a young adult individual. Molarization in PIMUZ A/V 5258 is evident as occurs in the deciduous premolars of fossil and living Tayassuidae ( Frailey & Campbell, 2012; Gasparini, 2007; Gasparini et al., 2011). Because of wear, it is rather difficult to describe in detail the tooth morphology (e.g., principal and accessory cusps) of PIMUZ A/V 5258.

Remarks

A systematic allocation for this isolated tooth (PIMUZ A/V 5258) is doubtful due to its incomplete preservation.

Cervidae Goldfuss, 1820

Morenelaphus Carette, 1922

Morenelaphus sp.

( Fig. 7A View Fig 1–A View Fig 3 View Fig ).

Referred material

An incomplete left antler (PIMUZ A/V 4162). Geographic data of the specimens are provided in Additional file 1.

Description and comparisons

PIMUZ A/V 4162 consists of a long and complex incomplete left antler ( Fig. 7A View Fig 1–A View Fig 3 View Fig ). Te preserved portion of antler shows the mean beam, fragmented anteriorly near the second ramification and with a rounded cross-section ( Carette, 1922; Kraglievich, 1932). Additionally, the second and third ramifications are directed forward, while the mean beam is backward. Te second and third ramifications form an angle of approximately 45 degrees at the intersection of their axes. Te antler is twisted on its own axis and has longitudinal grooves slightly marked along the external surface, following the torsion of the antler.

Remarks

According to Ameghino (1888b) and Alcaraz (2010), the mean beam in Morenelaphus is clearly curved backwards after the third ramification, as it is observed in PIMUZ A/V 4162. Traditionally, antlers have been used as diagnostic structures for different taxonomic levels within fossil Cervidae from South America ( Alcaraz, 2010; Ameghino, 1888b; Kraglievich, 1932). Some other studies have used other structures for taxonomical purposes ( Orcesi et al., 2019; Pêgo, 2014; Vezzosi, 2015; Vezzosi & Chimento, 2021). PIMUZ A/V 4162 is a fragment of antler without any other structure associated, which does not allow an assignment beyond Morenelaphus sp.

Morenelaphus is recognized by its long and huge antlers (e.g., Ameghino, 1888b; Cabrera, 1929b; Carette, 1922). Two species were described from Pleistocene deposits of Pampean region of Argentina: Morenelaphus brachyceros and Morenelaphus lujanensis . Te systematic distinction of both species is supported solely by the morphology of its antlers ( Alcaraz, 2010; Ameghino, 1888b; Cabrera, 1929b; Gervais & Ameghino, 1880; Menegaz, 2000); although some cranial and dental features help to differentiate these fossil forms ( Chimento et al., 2019; Rotti et al., 2021; Vezzosi & Chimento, 2021; Vezzosi et al., 2020). Te fossil record suggests that both Morenelaphus species belong to different biochronologic intervals within the Pleistocene ( Alcaraz, 2010; Cassini et al., 2016). Morenelaphus was considered a typical extinct deer from Pampean lowlands of Argentina, Uruguay, and southern to northern Brazil ( Cassini et al., 2016; Chimento et al., 2019; Ferrero et al., 2007; Kraglievich, 1932; Rotti et al., 2021; Ubilla & Martínez, 2016; Vezzosi et al., 2019). Some studies suggest grasses were the most frequent element in the diet of Morenelaphus ( Rotti et al., 2018) , although Tomassini et al. (2020), suggested more browser feeding preferences.

Cervidae indet.

( Fig. 7B View Fig 1–C View Fig 2 View Fig ).

Referred material

Left hemimandible with alveoli of p2 and p3–m3 series (PIMUZ A/V 4252), and mandible with left p4–m3 series and root of p2–p3, and right dentition with p3–m3 series (PIMUZ A/V 4284). Geographic data of the specimens are provided in Additional file 1.

Description and comparisons

PIMUZ A/V 4252 is a left hemimandible partially preserved with p3–m3 series and the alveoli of a p2

( Fig. 7B View Fig 1–B View Fig 3 View Fig ). Teeth do not show an advanced wear stage ( Fig. 7B View Fig 1 View Fig ). Te occlusal length of the molar series is 61 mm. PIMUZ A/V 4284 preserves both hemimandibles ( Fig. 7C View Fig 1–C View Fig 2 View Fig ). Te left dentition has the p4–m3 series and root of both p2–p3, while the right dentition preserves the p3–m3 series, but its m1 is lingually broken. Te length of the right m1–m3 series is 51 mm, and the left one is 52 mm. Teeth are bunoselenodont; most of cusps are differentiated, although well-developed cristids are present. Both mandibles are robust with a diastema shorter than that of any living South American deer.

Remarks

Te dentition of PIMUZ A/V 4252 and PIMUZ A/V 4284 have a premolar–molar series with six teeth as in Cervidae ( Heckeberg, 2020) , in contrast to five present in Camelidae ( Lynch et al., 2020) . Te presence of a short diastema is a morphological character that has been considered diagnostic of Morenelaphus ( Alcaraz, 2010; Chimento et al., 2019; Menegaz, 2000; Pêgo, 2014). Pêgo (2014) reported, in the molars of Morenelaphus , a U-shaped morphology in the labial section where the protoconid and hypoconid are present; while living Odocoileini ( Blastocerus , Odocoileus , Ozotoceros , Subulo, Pudu , and Hippocamelus ) have a V-shaped section. Te U-shape form is observed in the dentitions of both specimens PIMUZ A/V 4252 and PIMUZ A/V 4284 ( Fig. 7B View Fig 1, C1 View Fig ). However, mandibular remains with teeth associated to skulls with dentitions and/or antlers in Morenelaphus are unknown ( Vezzosi, 2015; Vezzosi & Chimento, 2021). Moreover, a short diastema is not possible to be recognized in PIMUZ A/V 4252 and PIMUZ A/V 4284, and other specimens of the genus as suggested by Chimento et al. (2019). In fact, the length of the diastema is highly variable during ontogeny in living deer and must be tested in a large comparative framework between South American species. In PIMUZ A/V 4252 and PIMUZ A/V 4284, the dentition, in occlusal view, is subparallel and positioned at the level of the m2–m3 with a more lingual projection in the hemimandible, while in the Camelidae ( Hemiauchenia paradoxa , Lama guanicoe , and Palaeolama major ) the cheek molars are positioned parallel with a labio-lingual direction to the hemimandible ( Lynch et al., 2020; Scherer et al., 2007). Te anterior fossetid opens at the mid-lingual portion of the trigonid in p4–m3 (e.g., Fig. 7B View Fig 1 View Fig ). Tere is no vestige of a back fossetid in m1 and m2; however, in m3 this fossetid opens lingually. Te hypoconulid is large and with a roundedshape. Tere is a circular fossa ( Fig. 7B View Fig 1 View Fig ). In South American Camelidae molariforms are smaller with an oval/ suboval shape and without a fossa. An anterior cingulid is recognized in p4, although weakly developed. We do not see an anterior cingulid in m1, due to preservation and wear stage. Te metaconid is the largest cups of the p4 trigonid. Te m3 has the metaconid with pronounced protostylid and parastylid, an uncommon feature among Pleistocene South American Camelidae ( Scherer et al., 2007) . According to Heckeberg (2020), ectostylids are variably present from one to three in the lower molars of Cervidae . Tose are never high, and are affected by advanced wear in aged individuals. Here an ectostylid in the m1 is observed ( Fig. 7B View Fig 1 View Fig ). We do not rule out that PIMUZ A/V 4252 and PIMUZ A/V 4284 could belong to either Morenelaphus or another American deer, since our comparisons do not allow to offer a more specific determination. It is necessary that these characteristics could be revised and tested in a broader comparative and phylogenetic framework to establish affinities with extant or extinct South American deer.

Perissodactyla Owen, 1848

Equidae Gray, 1821

Hippidion Owen, 1869

Hippidion principale ( Lund, 1846) .

Hippidion cf. H. principale

( Fig. 8A View Fig 1–B View Fig 2 View Fig ).

Referred material

A fragmented skull,?right talus articulated with the central tarsal bone, and a left first phalanx from the same individual (PIMUZ A/V 4100). Geographic data of the specimens are provided in Additional file 1.

Description and comparisons

PIMUZ A/V 4100 is an incomplete skull preserved only in its ventral side ( Fig. 8A View Fig 1 View Fig ). Te premaxilla bears the left I3, and both maxillae have canines and the complete right and left dental series P1–P4 and M1–M3. With the exception of P1, premolars and molars are robust and square-like in shape; premolars being larger than molars

( Fig. 8A View Fig 2–A View Fig 3 View Fig ). Occlusal length ranges approximately between 45 and 33 mm in premolars, and between 29 and 33 mm in molars. Te right M1–M3 series length is 92 mm, and the left is 94 mm. Te total length of the right series P1–M3 is 216 mm, and the left is 217 mm. Te wear on the premolars and molars is not advanced, allowing a clear observation of the dental morphology, which is characterized by oval to rounded protocone, a hypocone with angular/subtriangular shape, and a more pronounced parastyle than the mesostyle. Te pre/ postfossettes are visible only in the M1. Other cranial/ postcranial elements of presumably the same individual include two skull fragments in a poor state of preservation, a?right talus in fragmentary condition and articulated with the central tarsal bone, and a first left phalanx of the third digit of 85 mm in length ( Fig. 8B View Fig 1–B View Fig 2 View Fig ).

Remarks

According to Alberdi et al., (2005, 2006) the dentition of Hippidion is characterized by an oval to rounded protocone, character that is present in PIMUZ A/V 4100. Hippidion is considered an endemic genus from South America with a biochron spanning from the Pliocene to the Late Pleistocene ( Prado & Alberdi, 1996). Tree species have been recognized, (1) Hippidion principale , being the most robust species and the best known from the Argentinian Pampa, and with possible reports from Peru and Ecuador; (2) Hippidion devillei , which is an intermediate size species, with a fossil record throughout the central Andes of Peru and the Argentinian Pampa (although it may have reached as far north as Venezuela, see Labarca et al., 2021); and (3) Hippidion saldiasi , which is the smallest species, restricted to Late Pleistocene deposits from the Patagonian region and some localities further north in Chile (see Alberdi & Prado, 1993; Labarca et al., 2021; Prado & Alberdi, 2017). Hippidion saldiasi is a species named by Roth, 1899 (original nomination Onohippidium saldiasi Roth, 1899 ). Te differentiation between the Hippidion species combines an analysis of the skull and metapodial characters, with emphasis in the size and proportions of the appendicular bones ( Alberdi & Prado, 1993; Alberdi et al., 1995; Prado & Alberdi, 2017). PIMUZ A/V 4100 has dental characters similar to those of H. principale referred from Argentina, Brazil, and Tarija in Bolivia (e.g., Alberdi et al., 2001b, 2003, 2006; MacFadden, 1997; Prado et al., 2012, 2013). Te dimension of the M1–M3 series and total length of the P1–M3 series in PIMUZ A/V 4100 fit the range of length variability of H. principale . An assignment of PIMUZ A/V 4100 to the largest Hippidion species, H. principale , seems likely.