taxonID	type	description	language	source
03BC87B5776CB659F7BEFE0EEF1AFB77.taxon	type_taxon	Type species. Carodnia feruglioi Simpson, 1935 Emended diagnosis (after Simpson, 1935 a; Paula Couto, 1952; Vera et al., 2020). Carodniid xenungulates with pentadactyl, short and slender limbs, alternated carpal bones, and broad and flat ungual phalanges. Cervical vertebrae short. Complete brachyodont dentition, an anterior extension of the masseteric fossa onto the body of the dentary below the m 3, partially hidden in lateral view, by the mandibular ramus. P 1 – 2 / 1 – 2 with a main mesial cusp and labiolingually compressed. P 3 – 4 with V-shaped protocone and strong meso-external paracone. M 1 – 2 bilophodont, M 3 with well-developed protoloph. No diastema between c – p 1 – 2. The p 4 molariform with low and short crested talonid with hypolophid. Trigonid of m 1 – 2 short, formed by a high protolophid and short paracristid, metacristid if present, close to the mesial side of the protolophid; precingulid in m 1 – 2; no paraconid; and labial cingulid on the talonid of m 3.	en	Gelfo, Javier N., López, Guillermo M., Bond, Mariano (2024): New insights on the anatomy, paleobiology, and biostratigraphy of Xenungulata (Mammalia) from the Paleogene of South America. Palaeontologia Electronica (a 30) 27 (2): 1-34, DOI: 10.26879/1360, URL: https://doi.org/10.26879/1360
03BC87B5776CB656F7B7FB03EE3BFA8C.taxon	materials_examined	Holotype. MGP-PD 29046, mandible fragment with left m 3. Hypodigm. MGP-PD 29030 a-c type of Ctalecarodnia cabrerai: MGP-PD 29030 a, left p 4; MPEF-PV 1872, right dentary with m 2 – 3; MPEF-PV 1873, left dentary with p 4 and part of m 1; MPEF-PV 1874, left dentary with m 3; MGP-PD 29030 b, left m 2? With broken trigonid, and MGP-PD 29030 c, right m 2? with broken trigonid; MGP-PD 29030 d, a fragment of a cusp; MGP-PD 29030 e, trigonid fragment of a left m 1?; MGP-PD 29033 a, left i 3?; MGP-PD 29033 b, mesial lobe of a left M 2?; MGP-PD 29047, isolated right I 3; MLP-PV 34 - V- 22 - 8: right m 3, left and right p 2 – 3; MLP-PV 34 - V- 22 - 9, right p 4 (originally assigned to Ctalecarodnia cabrerai); UNPSJB-PV 680, a fragment of mandible with left canine and roots of p 2 – 3; UNPSJB-PV 680 - 1, a fragment of mandible with right m 1; UNPSJB-PV 680 - 2, a fragment of the left mandible with anterior root of m 3; UNPSJB-PV 680 - 3, anterior root of a right m 2.	en	Gelfo, Javier N., López, Guillermo M., Bond, Mariano (2024): New insights on the anatomy, paleobiology, and biostratigraphy of Xenungulata (Mammalia) from the Paleogene of South America. Palaeontologia Electronica (a 30) 27 (2): 1-34, DOI: 10.26879/1360, URL: https://doi.org/10.26879/1360
03BC87B5776CB656F7B7FB03EE3BFA8C.taxon	discussion	Remarks. We refer here to Carodnia feruglioi a left dentary with p 4 and the mesial part of trigonid of the m 1 (MPEF-PV 1873), a left dentary with m 3 (MPEF-PV 1874,), and a right dentary with m 2 – 3 (MPEF-PV 1872). These specimens were previously described as Carodnia cf. C. feruglioi and are probably of the same individual (Gelfo et al., 2008). They were found by Nestor Ronconi in levels of the Peñas Coloradas Formation, between Puerto Visser and Bahía Bustamante (45 ° 17 ’ 19 ” S, 67 ° 01 ’ 29 ” W) in Chubut province, Argentina. The main difference with materials previously assigned as C. feruglioi is the presence of a postcingulid, which projects from the distolabial side of the hypoconid to the labial cingulid, surrounding the hypoconulid. This feature was also present in the m 3 of C. vieirai as mentioned by Paula Couto (1952) and wrongly mentioned as absent in Gelfo et al. (2008) but missing in C. feruglioi and apparently in C. inexpectans (see Antoine et al., 2015: figure 2). Since there are no wear facets present on the distal wall of the talonid in the m 3, it can be inferred that there is no functional contact between the distal part of the M 3 and the postcingulid of the m 3 during the occlusion process. In most mammals, distal wear facets in the m 3 are typically confined to the mesial part of the hypoconulid, the postcristid, and the hypocristid, rather than in the postcingulid of the m 3 if it is present. Consequently, it is conceivable that the distal wall of the talonid in the m 3 remains relatively unaffected by selective pressures associated with chewing, allowing for the passive accumulation of a certain degree of morphological variation, such as the presence or absence of the postcingulid. Based on these dental observations and the overall similitude observed among the three specimens (i. e., MPEF-PV 1872, 1873, 1874) and the holotype of C. feruglioi, we have confidently attributed them to this species. The lot MLP-PV 34 - V- 22 - 8 belonging to a right m 3 left and right p 2 – 3, and MLP-PV 34 - V- 22 - 9 right p 4 were first described by Cabrera (1935) but interpreting the p 3 as P 3, and the p 4 as Ctalecarodnia cabrerai. Simpson (1967) partially illustrated these specimens correctly, and they were also discussed by Vera et al. (2020). However, the latter discussion was based on incomplete casts and several details of these specimens need to be highlighted considering their possible homologies. The main axis of the p 2 runs mesiodistal with the protoconid as the main cusp with two main wear facets prcd-h and prcd-b (Figure 3 A-C, G-I). The paracristid projects from it and bifurcates mesially in a strong precingulid which extends in a short portion labially and lingually. A strong distal cristid descends from the protoconid, up to a bifurcation which makes an inverted “ Y ” in the occlusal view (Figure 3 C, I). There is a small bulge or thickening of the distal cristid at the bifurcation point. The short lingual portion of the cristid contacts an entoconid sensu Cabrera (1935). The more labial cristid, here interpreted as cristid obliqua, descends and reaches a high, but not too strong hypoconid at an angle of approximately 90 ° in labial view (Figure 3 C). A postcingulid descends from the hypoconid to the lingual and labial sides. The hypoconulid is a small elevation with a strong wear facet (hd-mb) over the lingual postcingulid, with a soft facet pocgd-ml (Figure 3 A, C, I). The p 2 structure is comparatively more complex than the p 2 of C. vieirai, where no cusp or cristid was identified by Paula Couto (1952) who just did a topographical description. In the p 2 of C. vieirai, the protoconid is higher and more transversally compressed, the precingulid is less developed, the distal crest bifurcates in a short distolingual cristid with no entoconid associated, and a more distolabial cristid. The p 3 of MLP-PV 34 - V- 22 - 8 is more molarized with the protoconid as the main cusp but associated labially with a strong and a bit lower metaconid (Figure 3 D-F, J-L). The paracristid could be interpreted as in p 2 but there is an incipient paraconid? interrupting their continuity and from it, a mesial cristid contacts the precingulid (Figure 3 F). Two small basins are delimited distally to the precingulid, the lingual one, which is also mesial to the base of the metaconid, is larger than the labial one. The mesial wear facets are well developed on the labial side (pacd-mb, prcgd-b, prcd-b, prcd-db) (Figure 3 L). The talonid is also better defined than in p 2, with a short cristid obliqua, and a large hypoconid, which in both teeth shows a clear hd-mb wear facet. A distal and straight cristid also descends from the protoconid lingually, ending in a small entoconid. The talonid basin is larger than the p 2 delimited distally by a transverse postcingulid, which lingually seems to end in a small hypoconulid. This last cusp is close to the entoconid but separated from it by a short lingual opening of the talonid basin. In contrast to the similar size of p 2 and p 3 in Carodnia feruglioi and the features mentioned above, the p 3 of C. vieirai is smaller than their p 2 and differs in the absence of the metaconid and paraconid; also, the lingual distal cristid, is lees projected distally so the talonid basin present a wider lingual opening. Particularly, Paula Couto (1952) mentioned a variable present posterointernal cusp and a hypoconid, united by a smooth ridge. The p 4 (MLP-PV 34 - V- 22 - 9) was initially attributed to Ctalecarodnia cabrerai by Cabrera (1935), and it was comprehensively described by him and Vera et al. (2020). Hence, this discussion will focus on providing a few additional comments regarding its homologies. The cristid extending mesially from the metaconid, which does not contact the precingulid, as noted by Cabrera (1935), is here interpreted as the metacristid (Figure 3 M-O) as those identified by Vera et al. (2020) in the p 4 of MGP-PD 29030 a. The protoconid and metaconid are well identified in the protolophid, which is the highest structure of the tooth. The hypolophid is low, transverse, and well differentiated from the postcingulid. The resemblance of this p 4, as well as others assigned to C. feruglioi (see Vera et al., 2020) with the p 4 of C. vieirai is stronger than those between p 2 – 3. The primary distinctions lie in the labial extension of both the postcingulid and precingulid within the Itaboraian taxon. However, the degree of molarization is nearly identical in both species. The m 3 cusps identification for MLP-PV 34 - V- 22 - 8 mostly agrees here with those features referred to by Vera et al. (2020) for the holotype MGP-PD 29046. But, in contrast, the conulid placed mesiolingually to the hypoconid is here identified as plagioconulid (Figure 3 P-R). In Carodnia feruglioi this cusp is not easily identified even in specimens with scarce wear, since the hypoconid developed a lingual wear facet (hd-l) very quickly. In these specimens, the plagioconulid was probably rapidly erased by wear and integrated into a single wear facet with the hypoconid. Despite this, the presence of plagioconulid seems to be an important derived feature in the m 3 of C. feruglioi. Assigned materials. MPEF-PV 564 right dentary with the trigonid of the m 2; MPEF-PV 8165 right dentary with part of the canine, and premolars and molars alveoli. Geographic and stratigraphic provenance. Both specimens come from the Peñas Coloradas Formation, Rio Chico Group sensu Raigemborn et al. (2010), in Chubut province. MPEF-PV 564 was found by F. J. Goin in the outcrops located 5 km south of El Gauchito farm (45 º 13 ’ 53.8 ” S, 67 º 09 ’ 01.9 ” W). MPEF-PV 8165 was found by one of the authors (JNG) at Bajo Palangana, in a level of red sands partially covered by a fraction of whitish gray conglomerate sands, with a significant degree of weathering at 45 º 33 ’ 28.2 ” S, 67 º 17 ’ 43.1 ” W (Figures S 1 – S 2 in Appendix 1).	en	Gelfo, Javier N., López, Guillermo M., Bond, Mariano (2024): New insights on the anatomy, paleobiology, and biostratigraphy of Xenungulata (Mammalia) from the Paleogene of South America. Palaeontologia Electronica (a 30) 27 (2): 1-34, DOI: 10.26879/1360, URL: https://doi.org/10.26879/1360
03BC87B5776CB656F7B7FB03EE3BFA8C.taxon	description	Description and comparisons. MPEF-PV 8165 is a fragmentary right jaw more robust than MPEF-PV 564 (Table 1). It was found in several associated pieces that fit together, plus a more posterior portion with remains of the coronoid crest and distal edge of the m 3 alveolus (reconstructed in Figure 4 A-C). The rest of the jaw is preserved in two parts, conserved the base of the canine and roots of p 1 – m 2. The canine is transversely fractured practically at the height of the tooth’s neck (Figure 4 A, C). The preserved section is rounded (19.24 mm x 17 mm), and three layers of dentine can be observed (Figure 5). While this resembles the different layers of dentin such as hard orthodentine, orthodentine, osteodentine, and vasodentine identified in Xenarthra (Kalthoff, 2011), a microstructural analysis would be necessary to further deepen these types of comparisons. The innermost layer, no more than 0.6 mm wide, surrounds a wide pulp cavity (3.50 mm in diameter) and is only differentiated from the middle layer by its more yellowish coloration. The middle layer is the most homogeneous, compact, and wide (4.56 mm) and is easily differentiated from the outermost portion of dentine by what appears to be a line of fragility. The outermost part does not exceed 1.76 mm in thickness and is well differentiated from the middle layer, and in it, a structure of concentric rings is observed towards the outermost portion. There is practically no preserved enamel, except for a thin layer on some of its edges. Strong vertical striations are observed in the outer part, which also shapes the bony contour of the alveolus. In the canine of Carodnia vieirai, the enamel is thin and corrugated, so, likely, the dentine crenulations observed in this specimen (MPEF-PV 8165) had a similar layer of enamel, which is not preserved. While the direct observation of specimen UNPSJB-PV 680 has failed to verify the presence of the finely grooved enamel layer described for its canine (Vera et al., 2020), it is still probable that this layer was present as observed in C. vieirai. Therefore, the observed grooves in UNPSJB-PV 680 are more likely to be associated with the outer layer of dentine, as reported in the present jaw. Posterior to the canine there are seven alveoli in the first portion of the dentary, interpreted here as those of p 1 (with a single root), and p 2 – 4, (each of two roots). Our loci interpretation as p 1 – 4, rests in what is observed in Carodnia vieirai, where p 1 is small and single-rooted, (Figure 4 C). In the occlusal view, the inter-alveolar space between mesial and distal roots of the same premolar is mesiodistally longer than between the alveoli of successive teeth. The labial face of the premolar series is broken. The preserved portion of the symphysis is large and robust. The upper surface is labiolingually concave and the lower flat. A small foramen opens mesially, like in Carodnia vieirai (DGM 333 - M, see Paula Couto, 1952). The more mesial part is missing, and it extends backward distal to the p 3 locus. Paula Couto (1952) described for Carodnia vieirai a similar symphysis but in contrast, extended up to the posterior border of p 4 in the type specimen DGM 333 - M. We could not directly check this specimen, but in another jaw assigned by him to C. vieirai (cast AMNH 49848 of DGM 334 - M) the symphysis extends to the distal part of p 3 as in MPEF-PV 8165 (see also Paula Couto, 1952: plate 37: 1). This last criterion seems to have been followed by (Muizon et al., 2015) when they coded this character for Carodnia in their matrix. Three oval mental foramina are present below the position of the distal root of p 2, p 4, and m 1 as described for MPEF-PV 564. A rounded fourth smaller foramen is present between the canine and p 1, likely corresponding to the one described for C. vieirai beneath the p 1 (Paula Couto, 1952). Another similarly rounded foramen is present in the ventral side of the symphysis (see Figure S 3 and 3 D image available at http: // morphobank. org / permalink /? P 5193). A small mental foramen was previously mentioned by Paula Couto (1952) for C. vieirai, but positioned on the posterior part of the lower border of the symphysis, beneath the canine, rather than medially as observed in MPEF-PV 8165. Towards the distal portion of the MPEF-PV 8165 dentary, two additional smaller foramina are situated beneath the positions of the m 2 roots (Figure 4 A). The first is almost vertically aligned with the mental foramina, while the second is located below it but more anteriorly. The posterior portion of the dentary is fractured distally to the m 2, leaving only the ventral edge of the jaw visible at the m 3 locus. In this cross-section of the jaw, a relatively large mandibular canal is present at the base. However, at the level of m 1, the diameter of the canal is smaller, and in a more central position. The mandibular canal cannot be followed to the back of the jaw since it is broken. The last dentary segment, which bears the distal alveolus of the m 3, does not have direct contact with the anterior part. MPEF-PV 564 represents a fragmentary right jaw, retaining solely the trigonid of m 2 and a fragment of the mesial root of m 3 (Figure 4 D-F). The jaw is broken anterior to the p 3, preserving only a severely damaged distal portion of the symphysis. Moving distally along the dentary, a small segment of the coronoid crest is visible on the labial side. Unlike Carodnia vieirai (DGM- 333 and DGM- 334) and Carodnia inexpectans (Antoine et al., 2015), the extensive damage in the distal part of the jaw hinders the possibility of identifying the anterior foramen of the coronoid canal. In contrast to the alveoli surfaces of the distal root of m 2 and m 3, those of p 3 – m 1 are broken and eroded, not preserving the real upper margin of the bone. The dentary is robust, with a convex ventral profile below the m 2 – 3 and a straight one mesially. At the m 1 position, a small portion of the ventral margin of the dentary is missing. Three mental foramina occur in the mandible, each one located, respectively, below the position of the distal root of p 2, the p 4 as in Carodnia vieirai (Paula Couto, 1952), and another one under the m 1. The mesial fragment of the m 2 preserves the trigonid with a clear transverse protolophid with a wear facet that runs through the length of the lophid and slopes distally. Despite the protoconid and the metaconid being almost integrated into the protolophid, they still retain a rounded external surface, making them easily identified in occlusal view. The mesial part of the trigonid is short and there is no trace of paraconid. A blunt paracristid descends abruptly from the mesial border of the protoconid to the base of the tooth and then runs lingually. A precingulid runs from the lingual side mesial to the protoconid base, up to the metaconid but not reaching the labial margin. The precingulid is undulated, thinner and lower on the lingual side, and thicker and higher near the metaconid.	en	Gelfo, Javier N., López, Guillermo M., Bond, Mariano (2024): New insights on the anatomy, paleobiology, and biostratigraphy of Xenungulata (Mammalia) from the Paleogene of South America. Palaeontologia Electronica (a 30) 27 (2): 1-34, DOI: 10.26879/1360, URL: https://doi.org/10.26879/1360
03BC87B57763B651F7F8FAC6EB0CFED1.taxon	description	Figure 6 A-D zoobank. org / 2705 DBC 8 - B 740 - 4 FAD- 9859 - 76 DD 6357 CC 5 A	en	Gelfo, Javier N., López, Guillermo M., Bond, Mariano (2024): New insights on the anatomy, paleobiology, and biostratigraphy of Xenungulata (Mammalia) from the Paleogene of South America. Palaeontologia Electronica (a 30) 27 (2): 1-34, DOI: 10.26879/1360, URL: https://doi.org/10.26879/1360
03BC87B57763B651F7F8FAC6EB0CFED1.taxon	materials_examined	Holotype. MLP-PV 90 - II- 12 - 121: right jaw fragment somewhat weathered, with m 1 nearly complete and p 4 with the basal portion and roots partially preserved.	en	Gelfo, Javier N., López, Guillermo M., Bond, Mariano (2024): New insights on the anatomy, paleobiology, and biostratigraphy of Xenungulata (Mammalia) from the Paleogene of South America. Palaeontologia Electronica (a 30) 27 (2): 1-34, DOI: 10.26879/1360, URL: https://doi.org/10.26879/1360
03BC87B57763B651F7F8FAC6EB0CFED1.taxon	etymology	Etymology. The species name karuen means “ old ” or “ ancient ” in the extinct language of the Aónikenk people, who inhabited Patagonia before the formation of the nation-states of Chile and Argentina. Geographic and stratigraphic provenance. Lower fossil level at Cerro Redondo, east of the Chubut province, Argentina (see Simpson, 1935 a). Río Chico Group, Peñas Coloradas Formation, lower Paleocene sensu Clyde et al. (2014). Found GELFO, LÓPEZ, & BOND: SOUTH AMERICAN XENUNGULATA by J. L. Prado in a Museo de La Plata field trip directed by Rosendo Pascual in 1991.	en	Gelfo, Javier N., López, Guillermo M., Bond, Mariano (2024): New insights on the anatomy, paleobiology, and biostratigraphy of Xenungulata (Mammalia) from the Paleogene of South America. Palaeontologia Electronica (a 30) 27 (2): 1-34, DOI: 10.26879/1360, URL: https://doi.org/10.26879/1360
03BC87B57763B651F7F8FAC6EB0CFED1.taxon	diagnosis	Diagnosis. Medium-size xenungulate, smaller than Carodnia vieirai and larger than Etayoa bacatensis, and somewhat larger than C. feruglioi. Protolophid of m 1 with a strong metaconid and a bit smaller protoconid. Trigonid basin not open lingually but is enclosed by large and well-defined paracristid and metacristid, which are closely pressed against the mesial side of the protolophid in the m 1. Precingulid strong and forms a conspicuous shelf as in C. inexpectans but differs from it for being higher and better developed on the lingual side. Hypolophid lower than protolophid, with a strong hypoconid and entoconid. Unlike all other Carodnia species, in which the cristid obliqua is absent in the first molar, C. karuen has a short cristid obliqua extending from the hypoconid up to the base of the distal wall of the trigonid, closer to the lingual side of the protoconid. Also differs from Carodnia feruglioi and C. vieirai for a short entocristid similar to those present in the m 3 of C. inexpectans but differing from it in being higher, and almost at the same height as the hypolophid. Broad talonid basin, open lingually.	en	Gelfo, Javier N., López, Guillermo M., Bond, Mariano (2024): New insights on the anatomy, paleobiology, and biostratigraphy of Xenungulata (Mammalia) from the Paleogene of South America. Palaeontologia Electronica (a 30) 27 (2): 1-34, DOI: 10.26879/1360, URL: https://doi.org/10.26879/1360
03BC87B57763B651F7F8FAC6EB0CFED1.taxon	description	Description and comparisons. The mesiodistal length of m 1 measures 18.21 mm, while the labiolingual dimension is 13.49 mm. The jaw presents two loci preserved, the mesial one with the roots of and part of the enamel of the tooth at the neck is here interpreted as a p 4 (Figure 6). The distal one is an m 1 with a nearly complete crown structure. The loci assignation rests in the preserved structure of this last tooth, which matches with those present in m 1 – 2 of all Carodnia species. In addition, the roots of the preceding tooth here interpreted as a p 4, preserve a distolingual enamel portion of the taloned, which is below the level of the precingulid of the succeeding tooth. This suggests that the more mesial dental piece erupted after the distal one, which agrees with the interpretation of a p 4 and m 1 for these teeth, following the usual order of eruption in most placental mammals. The lower portion of the jaw is broken, the ramus is robust, high, and at least three times the height of the m 1 crown. The lingual side of the dentary is convex, and the labial side is something concave. In contrast to the known jaws of C. feruglioi (UNPSJB-PV 680 - 1, MPEF-PV 564, and MPEF-PV 8165) there is no foramen in the labial side of the dentary below the mesial root of m 1. The p 4 is only preserved by a distolingual portion of enamel against the mesial root of the m 1, a short piece of dentine at the talonid, and the mesial and distal roots. The roots are mesiodistally compressed and broken on the labial side. The mesial fracture of the jaw exposes the trigonid root of p 4, which in frontal view is deep about the high of the preserved dentary. The m 1 is well preserved, with the trigonid somewhat higher, wider, and longer than the talonid. This tooth shows an almost labiolingually oriented bilophodont structure characteristic of Carodniidae. At the mesiolingual side of the trigonid, the enamel is broken and absent from the base of the crown exposing the dentine in the metaconid position. A strong precingulid is sloping down to the labial side and despite being broken, it seems that is not expanded over the labial and lingual side of the tooth. The protolophid like those of the m 1 of Carodnia vieirai, is mesially concave in occlusal view, with the cutting plane of the lophid parallel to the one of the hypolophid. The wear facets prld-d and hyld-d are equally developed. The metaconid can be distinguished from the protolophid by a strong enamel edge that bends at the lingual tip of the lophid. The protoconid is not so clearly observed from its occlusal outline. In contrast to C. vieirai or the m 2 – 3 in C. feruglioi and C. inexpectans where no cristids are developed mesial to the protolophid, C. karuen has a conspicuous paracristid and metacristid. The paracristid abruptly descends mesiolingually from the labial end of the protolophid, and progressively bends lingually, to the mesial base of the trigonid. The short metacristid projects mesiolabially from the metaconid almost reaching the lingual end of the paracristid. Mesially the paracristid and metacristid are close together but their contact, closing the trigonid, is inferred since a portion of enamel is missing. At the mesial base of the tooth and below most of the lower part of the paracristid, there is a remnant of a strong precingulid, which leans from the lingual side of the trigonid to a more basal position in the labial side. The hypolophid is the principal structure of the talonid and with a similar development to other Carodnia species. In the hypoconid sector of the hypolophid, a smooth cristid obliqua descends up to the base of the distal wall of the trigonid more approximately to the protoconid area. The cristid obliqua is smooth and runs mesiolingually, so the short talonid basin, which is open lingually, is also closed labially by it. The entoconid could be identified in the hypolophid by an enlargement at the lingual end, like the one observed in the metaconid but ovoid in outline rather than circular, and with thinner enamel. A very short entocristid runs mesiolingually from the entoconid. The entocristid delimited a short but high lingual edge of the talonid, which in contrast to the protolophid and the hypolophid lacked any wear. Behind the hypolophid base, a short portion of a strong and flat postcingulid is preserved. Even though the cingulid is far from being complete, it appears to have formed a long ledge or step in the distal part of the molar. The anterior root of m 1 is stronger than the posterior one, with both roots being mesiodistally compressed and swollen. There are certain similarities between C. karuen and in general, with the m 1 of Carodnia species, and the first molar of the Pyrotheria Carolozittelia tapiroides Ameghino, 1901 (MACN A- 10666) and Carolozittelia cf. C. tapiroides (MACN 17985) described by Kraglievich (1957). Both exhibit a bilophodont pattern with a slightly larger protolophid than the hypolophid (usually described in them as “ metalophid ” and “ entolophid ”, respectively), the wear facets prld-d and hypld-d, and the presence of enamel crenulations. However, significant differences can be highlighted, particularly with C. karuen, such as the absence in C. tapiroides of a metacristid resulting in a lingually open trigonid, a more robust paracristid in the region of the protoconid, the absence of an oblique cristid, a hypolophid of nearly equal height to the protolophid, and a greatly expanded labial postcingulid forming a large distal ledge. These differences, plus the structure of the third lobe in the m 3 of C. tapiroides, set it apart from the typical xenungulate dental pattern of m 3 present in Carodniidae and Etayoidae. However, considering a possible phylogenetic link between Xenungulata and Pyrotheria, as explored by some studies (Gelfo et al., 2008; Muizon et al., 2015), C. tapiroides exhibits the highest number of shared dental features among them.	en	Gelfo, Javier N., López, Guillermo M., Bond, Mariano (2024): New insights on the anatomy, paleobiology, and biostratigraphy of Xenungulata (Mammalia) from the Paleogene of South America. Palaeontologia Electronica (a 30) 27 (2): 1-34, DOI: 10.26879/1360, URL: https://doi.org/10.26879/1360
03BC87B57764B652F4CBFE85E811F9F0.taxon	type_taxon	Type species. Notoetayoa gargantuai Gelfo, López, and Bond, 2008 Figure 7 A-C Assigned material. UNPSJB PV 766 isolated left p 2. Geographic and stratigraphic provenance. The tooth was found at “ Tiro Federal Coronel Pringles ” by Mónica Abril in Gaiman locality, Chubut province, and comes from the white to pink arkosic sandstone of the Rio Chico Group. This level was assigned to Las Flores Formations (Chornogubsky et al., 2023).	en	Gelfo, Javier N., López, Guillermo M., Bond, Mariano (2024): New insights on the anatomy, paleobiology, and biostratigraphy of Xenungulata (Mammalia) from the Paleogene of South America. Palaeontologia Electronica (a 30) 27 (2): 1-34, DOI: 10.26879/1360, URL: https://doi.org/10.26879/1360
03BC87B57764B652F4CBFE85E811F9F0.taxon	discussion	Comments. The specimen was preliminarily identified in the collection of UNPSJB as a p 2 of Carodnia. Considering the common presence in the Carodnia zone of C. feruglioi and Notoetayoa gargantuai (Gelfo et al., 2008), the similitude of UNPSJB PV 766 with the p 2 Etayoa bacatensis, the differences with known p 2 of C. feruglioi and C. vieirai, and their size, is here assigned to N. gargantuai.	en	Gelfo, Javier N., López, Guillermo M., Bond, Mariano (2024): New insights on the anatomy, paleobiology, and biostratigraphy of Xenungulata (Mammalia) from the Paleogene of South America. Palaeontologia Electronica (a 30) 27 (2): 1-34, DOI: 10.26879/1360, URL: https://doi.org/10.26879/1360
03BC87B57764B652F4CBFE85E811F9F0.taxon	description	Description and comparisons. The tooth exhibits similarities to the p 2 of Etayoa bacatensis (GM- 32) than to any other SANU, in terms of its labiolingual compression, presence of two mesiodistally aligned roots, a robust and centrally positioned protoconid, and a relatively short and simplified talonid (Figure 7 D-F). These characteristics distinguish it from those of Carodnia feruglioi and C. vieirai. However, it differs from E. bacatensis in its substantially larger size and the absence of cusps in the talonid. The specimen displays a translucent and thin enamel, albeit with surface roughness. Although the roots are missing, there are indications of the presence of two roots, the mesial one larger, as the condition observed in Etayoa (Villarroel, 1987). The tooth is labiolingually compressed, with its main axis oriented mesiodistally (16.25 mm x 8.94 mm) and a strong labial wear facet over the enamel of the distal side, which is similar in position and orientation to the hy-mb wear facet in the p 2 of Carodnia feruglioi (MLP-PV 34 - V- 22 - 8, Figure 3 I), and is here considered homologous to it base on its position since no hypoconid could be identified (Figure 6 B-C: hd-b). The protoconid is the only identifiable cusp, slightly rounded at the base, with a flat wear surface (i. e., prcd-h), and the distal and mesial cristids are present. A strong paracristid descends mesially from the apex of the protoconid and in occlusal view, bends a bit lingually before reaching a small elevation from which two structures depart. The first is an almost vertical cristid in the mesial side of the tooth, and the other is a strong and crenulated precingulid that continues in a lingual cingulid and surrounds the base of the protoconid. In lateral view, the paracristid is a high ridge that forms a mesial and convex blade. A distal cristid, partially broken, also descends from the protoconid apex but not with such an abrupt angle as in the paracristid. Distally, it turns lingually down to the base in a postcingulid. The possible contact of the postcingulid and the lingual cingulid cannot be determined since the enamel is broken. In addition to its larger size, there exist other distinguishing features between the p 2 of Notoetayoa and Etayoa bacatensis (Figure 7). These distinctions include a notably more pronounced mesial bifurcation of the paracristid and the presence of a well-developed lingual cingulum in Notoetayoa. Conversely, the distal portion of the p 2 in E. bacatensis is wider and displays two cusps as described by Villarroel (1987), a distal and lower cusp, here identified as the hypoconid (Figure 7 E- F), and on its lingual side, a faint bump, which, regrettably, could not be corroborated in our photographs or casts. This latter feature may be homologous to the entoconid of the p 2 found in Carodnia feruglioi (Figure 3 C). The p 2 of Notoetayoa also differs from the p 2 of C. feruglioi and C. vieirai. Despite the paracristid in these species being shorter and bifurcates mesially as in Notoetayoa, the precingulid is strong in C. feruglioi and extends in a short portion labially and lingually (Figure 3 C), while in C. vieirai (DGM 334) is a sharp ridge with the lingual portion of the precingulid more extended over the base of the protoconid. Probably the vertical cristid here identified in Notoetayoa is homologous to the labial component of the precingulid in Carodnia, but with a modified position consequence of the lingual bend of the paracristid. Other differences with Notoetayoa rest in the further development of the talonid cups in the Carodnia species.	en	Gelfo, Javier N., López, Guillermo M., Bond, Mariano (2024): New insights on the anatomy, paleobiology, and biostratigraphy of Xenungulata (Mammalia) from the Paleogene of South America. Palaeontologia Electronica (a 30) 27 (2): 1-34, DOI: 10.26879/1360, URL: https://doi.org/10.26879/1360
