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International audience; The appendicular skeleton of tetrapods is a particularly integrated structure due to the shared developmental origin or similar functional constraints exerted on its elements. Among these constraints, body mass is considered strongly to influence its integration but its effect on shape covariation has rarely been addressed in mammals, especially in heavy taxa. Here, we propose to explore the covariation patterns of the long bones in heavy animals and their link to body mass. We investigate the five modern rhinoceros species, which display an important range of bodyweight. We used a 3D geometric morphometric approach to describe the shape covariation of the six bones composing the stylopodium and zeugopodium both among and within species. Our results indicate that the appendicular skeleton of modern rhinos is a strongly integrated structure. At the interspecific level, the shape covariation is roughly similar between all pairs of bones and mainly concerns the muscular insertions related to powerful flexion and extension movements. The forelimb integration appears higher and more related to body mass than that of the hind limb, suggesting a specialization for weight support. The integration of the stylopodium elements does not seem to relate to body mass in our sample, which suggests a greater effect of shared developmental factors. Conversely, the covariation of the zeugopodium bones seems more associated with body mass, particularly for the radius-ulna pair. The fibula appears poorly integrated with other bones, especially within non-Rhinoceros species, which may represent a case of parcellation due to a functional dissociation between the hind limb bones. The exploration of the integration patterns at the intraspecific level also highlights a more prominent effect of age over individual body mass on shape covariation within C. simum. This study lends support to previous hypotheses indicating a link between high body mass and high integration level.

Simoclaenus sylvaticus Muizon & Cifelli, 2000 EMENDED DIAGNOSIS. ��� Dental formula: I?/?, C 1/1, P 4/4, M 3/3; relatively large short-snouted kollpaniine characterized by the strong mesiodistal compression of its lower molars and premolars, which is correlatively observed on the M2; upper canine transversely compressed; P1 vertically implanted; P2 with a small protoconal bulge on lingual side of paracone; P3-4 with well-developed protocone (slightly larger on P4); M1 much smaller than M2; M2 almost square in occlusal outline but distinctly asymmetrical as in Molinodus; p4 with a well-developed metaconid medial to protoconid; molars with a large metaconid, posterior to the protoconid and with a posterior projection that partially fills the talonid basin; protoconid distinctly smaller than in Andinodus; posterior wall of trigonid sigmoid in occlusal view; paraconid and paracristid smaller than in Andinodus; large hypoconid with a labial slope less vertical than in Andinodus; cristid obliqua meets trigonid on lingual edge of protoconid. Ascending process of the maxilla short, high, and erected, premaxilla-maxilla suture subvertical in lateral view; frontal-maxilla suture present (therefore absence of nasal-lacrimal suture) anterior opening of infraorbital canal at level of P3. Rostrum, blunt and short as indicated by cheek teeth mesiodistal compression, implantation of anterior premolars, and subvertical premaxilla-maxilla suture. HYPODIGM. ��� The type specimen, MHNC 8332, a fairly complete right dentary with the alveoli of c, p1, the roots of p2, the alveolus of p3, and p4-m3. The dentary is lacking the anterior region with the incisor alveoli and most of the coronoid process; MHNC 8348, a right maxilla with M1 lacking the parastylar region and part of the paracone and M2-3 complete; MHNC 13868, a right maxilla with root of the canine and P1-P4; MNHC 13872, a partial mandible with alveolus of p1, roots of p2-3and p4-m1; MHNC 13876 a right maxilla fragment with M1-M2. DESCRIPTION Three new specimens are referred to this species. MHNC 13872 is a mandible fragment with the alveolus of p1, the roots of p2-3 and p4-m1 (Fig. 7). The alveolus of p1 is vertical as in the holotype of Simoclaenus sylvaticus (MHNC 8332) (Muizon & Cifelli 2000), indicating that the tooth was not procumbent in contrast to the condition observed in Molinodus (see above). This feature, shared by the holotype of Simoclaenus sylvaticus and the new specimen clearly supports the referral of the latter rather than to Molinodus suarezi, the p1 of which is procumbent (Fig. 1A, B). However, the major characteristic of this specimen lies in its p4, which is markedly compressed mesiodistally as is observed on the holotype. As in the latter, the metaconid is placed lingually to the protoconid and is not shifted posteriorly as is observed in Molinodus suarezi (Fig. 1D). Furthermore, the p4 of MHNC 13872 has the same strongly bulbous morphology as that of the holotype. The m1 is relatively worn but does not depart significantly from that of the holotype in terms of morphology. However, the two specimens differ in their size and the new specimen described here is distinctly smaller than the holotype (Table 2). As a matter of fact, the p4 and m1 of the new specimen are in average 10% smaller than those of the holotype (mean of the four ratios of Table 2). Although significant, this difference could be interpreted as related to individual size variation. The other large ���condylarth��� to which this specimen could be related is Molinodus suarezi, although this taxon is clearly smaller than Simoclaenus sylvaticus. However, the p4 observed on the mandible of M. suarezi described above (Fig. 2A) is so different from that of MHNC 13872 that we rather favor a strong individual size variation in S. sylvaticus than morphological variation in M. suarezi. A well-preserved lateral ascending process of a right maxilla (MHNC 13868) is referred to Simoclaenus sylvaticus. This specimen bears the root of the canine and the four premolars, which were unknown for this taxon (Fig. 8). The upper premolars of MHNC 13868 are only slightly larger than those of Molinodus suarezi described by Muizon & Cifelli (2000: 59), but this difference could be interpreted as related to individual variation in size. The major criterion that convinced us to relate this specimen to S. sylvaticus is the size of the canine. Although the crown of that tooth is not preserved the section of the root at the level of the alveolar border is relevant to its size. It is noteworthy that no upper canine is known for M. suarezi. We therefore compared the section of the upper canine of MHNC 13868 to that of the lower canine of MHNC 13883. Because the Tiupampa kollpaniines are relatively unspecialized, it is hypothesized that the width and length (at the level of the alveolar plane) of the upper and lower canines did not differ significantly even if generally the upper canines are slightly larger than the lowers. This remains an assumption, as no kollpaniine has ever been documented by both upper and lower canines. Here, the upper canine of MHNC 13868 (Simoclaenus) is 87% longer and 55% wider than the lower canine of MHNC 13883 (Molinodus) (Table 3). Even taking into account the approximation in comparing upper and lower canines, such a size difference is highly significant and we regard as unlikely that the two canines could belong to the same taxon of kollpaniine. We therefore, tentatively refer MHNC 13868 to S. sylvaticus rather than to M. suarezi. Furthermore, the size difference between the P4 and M1 of the holotype of S. sylvaticus and referred specimen described here could be related to sexual dimorphism in this species as evoked above. The premolars are well preserved and bear very reduced dental wear. The size of P3 and P4 is slightly larger than the equivalent teeth in Molinodus suarezi, which are known on one specimen only (MHNC 1247) (see Muizon & Cifelli 2000: 58) (Table 4). P1 and P2 are unknown for M. suarezi. Although this size difference is moderate (c. 10%), because of the large size of the canine, we rather refer this specimen to Simoclaenus sylvaticus. Furthermore, the anteroposterior length of the upper premolar row of MHNC 13868 (11.31 mm) is only slightly smaller than the lower premolar row of the holotype of S. sylvaticus (11.97 mm), on which the alveoli of p1-3 and the p4 are preserved. Therefore, the mesiodistal length of the upper premolar row of the new specimen (MHNC 13868) correctly matches the length of the lower premolars row of the holotype (MHNC 8348). P1 is peg-like, single-rooted, and compressed transversely. It is implanted vertically in the maxilla as is observed on the alveolus of the p1 of the holotype (MHNC 8348). This condition suggests a relative shortness of the rostrum and is congruent with the anteroposterior compression of the lower cheek teeth observed on the mandible. It is noteworthy that the p1 of Molinodus described above (MHNC 13883) differs from the condition observed in Simoclaenus in being slightly procumbent, thus suggesting a more elongated rostrum. As preserved, the P1 of Simoclaenus on MHNC 13868 is longer than high and no significant wear facet can be observed at the apex of its crown. In lateral view the tooth is roughly symmetrical anteroposteriorly. A small diastema separates P1 from the canine anteriorly and from P2 posteriorly. P2 is triangular in occlusal view and bears three roots. It is longer than wide. It presents a conspicuous inflation on its distolingual edge, which can be regarded as an incipiently developed protocone (protoconal bulge). The paracone forms most of the tooth and is as high as long. Its mesial edge is wide and blunt whereas its distal edge is thin and forms a sharp crest. The tooth bears no cingulum but a small cusp at the distolabial edge of the paracone could be regarded as a metastyle. This style contacts the anterior edge of P3 and no diastema separates the two teeth. P3 is slightly wider than long, triangular in occlusal view, and bears three roots. The mesial and distal edges are markedly concave, a condition which individualizes a well-developed protocone lingually. This cusp is approximately two thirds the height of the paracone. It is as long as wide. It has a very convex lingual edge and a flat labial aspect. These two edges of the tooth are separated by sharp pre- and postprotocristae, which join the base of the crown at the level of the greatest concavity of the mesial and distal edges of the tooth. Labially the paracone is approximately twice as long as wide. Its mesial edge bears a smooth crest and its distal crest is slightly obliterated by an elongated wear facet, which extends from the apex of the tooth to the posterior base of the paracone. At the mesial angle of the paracone is a marked parastyle. From this cusp, a conspicuous cingulum extends on labial edge of the paracone. At the distal end of the cingulum is a small metastyle. P4 has a pattern similar to that of P3 but it is mesiodistally shorter and transversely wider. Its mesial and distal edges are slightly concave but to a much lesser extent than the condition observed on P3. The paracone is smaller (in height and volume) and the protocone is more voluminous than on the preceding tooth. The pre- and postprotocristae are more developed than on P3 and extend on the anterior and posterior edges of the paracone. The postprotocrista even joins the distolabial angle of the tooth and contacts the postparacrista. The latter bears a narrow wear facet on its mesial two thirds only. The distal end of the postparacrista bears, on its lingual aspect, a hint of inflation, which can be interpreted as an incipient metacone. A tiny inflation on the postprotocrista may also be regarded as an incipient metaconule. On the distal edge of the protocone, is a distinct postcingulum. On its mesial edge the precingulum is weakly developed. On the mesiolabial angle of the tooth the parastyle is more developed than on P3. From this style, a well-developed labial cingulum extends distally until the metastylar angle of P4. Little is preserved of the palatal process of the maxilla, but the lateral wall of the rostrum from the anterior edge of the canine to the anterior root of the zygomatic arch is relatively complete and all its edges likely correspond to sutures with adjacent bones except for a small U-shaped-break in the posterodorsal angle (Fig. 8C). The anterodorsal edge of the specimen probably corresponds to the nasal-maxilla suture. Approximately above the P1-P2 embrasure, the edge of the maxilla distinctly protrudes medially. Anterior to this indentation, the suture is apparently anteroposteriorly oriented or slightly oriented anterolaterally. Posterior to it, the suture diverges posterolaterally, thus indicating a widening of the nasals posteriorly, as generally observed in early diverging metatherians and eutherians (e.g., deltatheroidans, pucadelphydans, Zalambdalestes, Kulbeckia, Alcidedorbignya). On the posterior limit of the maxilla, as preserved, is a deep groove probably for the articulation of the anterior process of the jugal. This groove (maxillajugal suture) approximately corresponds to the level of the anterior edge of the orbit and the posterior limit of the rostrum, which corresponds to the posterior edge of P4. On the posterodorsal angle of the specimen, in lateral view, is a distinct small notch (dorsal to the breakage notch mentioned above), which was receiving the anterolateral angle of the frontal. If this interpretation is correct, the nasal and lacrimal of Simoclaenus were distinctly separated, which likely represents a crown Placentalia condition (frontal-maxilla suture present) (Muizon et al. 2015). The posterior edge of the maxilla, between this notch and the dorsal end of the jugal groove, likely corresponds to the lacrimal-maxilla suture. Anteriorly, several grooves mark the edge of the maxilla immediately anterior to the canine, which we interpret as the premaxilla-maxilla suture. This suture is almost straight, slightly concave anteriorly, and sub-vertical, forming an angle of approximately 95�� with the alveolar plane (Fig. 8C). The lateral aspect of the maxilla is markedly elevated and erected, to a greater extent than the condition observed in the pantodont Alcidedorbignya inopinata from the same locality (Muizon et al. 2015). This condition apparently resembles that of Baioconodon nordicum (YPM-PU 14234) from the earliest Palaeocene (Puercan) of Mantua lentil of Wyoming. The anterior opening of the infraorbital canal is 2.08 mm high and located above the mesiolabial root of P3. In this respect Simoclaenus differs from the condition in Maiorana and Baioconodon, in which the infraorbital foramen is located more posteriorly, above the mesiolabial root of P4. A condition similar to that of Maiorana and Baioconodon is observed in Didolodus multicuspis (MACN 10690), in which the infraorbital foramen is located above the distal edge of P3 and most of the P4 (Gelfo, personal communication). Anterior to this foramen is a tiny opening located above the anterior root of P2, and which probably represents a nutrient foramen. In its anterior region, the maxilla is not inflated laterally by the canine as is observed in Alcidedorbignya, due to the fact that the canine was compressed transversely. This condition particularly resembles the ���condylarths��� of Mantua lentil of Wyoming, Baioconodon and Maiorana. The third specimen referred to Simoclaenus sylvaticus is a partial maxilla with M1-2 (MHNC 13876), (Fig. 9). The M2 perfectly matches the size and morphology of that of MHNC 8348 described by Muizon & Cifelli (2000). The small differences between the two teeth are the presence, in MHNC 13876, of a slightly larger parastyle, a cuspule on the preparaconular crista located between the paraconule and the parastyle and a slight inflation of the lingual end of the precingulum (cuspule?). The M2 of MHNC 13876 has the characteristic asymmetrical morphology observed in Molinodus and Simoclaenus, in which the paracone is distinctly more labial than the metacone (Muizon & Cifelli 2000: fig. 2A-C, fig. 14C). This condition is not observed on the M1 of Molinodus, the paracone of which is not shifted labially. The most interesting characteristic of this specimen is in the relative wear stage of the M2 and M1. The M2 has a wear stage approximately similar to that of the M2 of MHNC 8348. In contrast the M1 is totally excavated in its lingual two thirds: the protocone, the protocristae and the conules, the pre-and postcingula, and the trigon basin have disappeared; the only preserved elements of the tooth are the para- and metacones, the styles and the labial cingulum. This wear stage is clearly more advanced than that observed on the M1 of MHNC 8348, in which the protocone and conules are coalescent but still identifiable, the protocristae and the pre-and postcingula are distinctly observable. This stage of wear of M2-1 of MHNC 8348 is comparable to that observed on the maxilla of Molinodus suarezi (MHNC 1247) described by Muizon & Cifelli (2000). In fact, the extensive wear of the M1 of MHNC 13876 is comparable to the condition that could be observed on a DP4, an interpretation impossible given the fact that the posterior tooth is undoubtedly an M2, which presents the characteristic asymmetrical morphology of that tooth (Muizon & Cifelli 2000). Furthermore, the roots of the M1 are long and the lingual root perforates the floor of the orbit, which suggests that it is not a deciduous molar. In ventral view, laterally to M2, the maxillar process of the zygoma and the anterior border of the orbitotemporal fossa are preserved. The latter is at the level of the apex of the metacone of M2, while it is at the level of the paracone of M3 on the maxilla (MHNC 8348) referred to Simoclaenus by Muizon & Cifelli (2000). In Molinodus the anterior edge of the orbitotemporal fossa is at the level of the paracone of M3 and in Baioconodon (YPM-PU 14234) and Maiorana (YPM-PU 16667 and 14171) it is at the level of the metacone of M3. However, this condition is likely to be individually variable since in Alcidedorbignya inopinata out of 13 specimens, in which it can be observed, three of them (see Muizon et al. 2015: fig. 10B) have an anterior edge of the orbitotemporal fossa at the level of the metacone of M2, as observed in the Simoclaenus specimen described here. In the other ten specimens, the anterior edge of the fossa is at the level of the paracone of M3. In the Alcidedorbignya sample the anterior position of M2 is observed in young adults and may be related to the ontogenetic increase of the length of the rostrum., Published as part of Muizon, Christian de, Billet, Guillaume & Ladev��ze, Sandrine, 2019, New remains of kollpaniine " condylarths " (Panameriungulata) from the early Palaeocene of Bolivia shed light on hypocone origins and molar proportions among ungulate-like placentals, pp. 841-874 in Geodiversitas 41 (25) on pages 851-855, DOI: 10.5252/geodiversitas2019v41a25, http://zenodo.org/record/3699898, {"references":["MUIZON C. DE & CIFELLI R. L. 2000. - The \" condylarths \" (archaic Ungulata, Mammalia) from the early Palaeocene of Tiupampa (Bolivia): implications on the origin of the South American ungulates. Geodiversitas 22 (1): 47 - 150.","MUIZON C. DE, BILLET G., ARGOT C., LADEVEZE S. & GOUSSARD F. 2015. - Alcidedorbignya inopinata, a basal pantodont (Eutheria, Mammalia) from the early Palaeocene of Bolivia: anatomy, phylogeny, and palaeobiology. Geodiversitas 37 (4): 397 - 634. https: // doi. org / 10.5252 / g 2015 n 4 a 1"]}

Tiuclaenus minutus Muizon & Marshall, 1987 DIAGNOSIS. ��� See Muizon & Cifelli (2000). DESCRIPTION A maxilla with M1-3 (MHNC 13879) is referred to Tiuclaenus minutus. It bears three almost unworn molars, and has been referred to this species essentially on the basis of its size (Fig. 10A). Tiuclaenus minutus is the smallest ���condylarth��� species of the Tiupampa fauna and the molars of the new specimen are even slightly smaller than those of MHNC 1240 described by Muizon & Cifelli (2000: fig. 7C). For example, the length of the molar row is 5.86 mm in MHNC 13879, while it is 6.74 mm on MHNC 1240, but such a size difference is likely related to individual variation. The size and proportions of the upper molar of this specimen depart from the other species of Tiuclaenus and from Pucanodus, which are distinctly larger (see Muizon & Cifelli 2000: tables 7-9). However, some slight morphological differences exist between the specimens referred to T. minutus, which differ in the larger size of the para- and metastyles, the para-and metacones more approximated, the more pronounced ectoflexus and labial cingulum. Nevertheless, in spite of these morphological differences we tentatively refer MHNC 13879 to T. minutus, considering that they could regarded as related to individual variation, an interpretation that could be revised when a larger sample of that species will be available., Published as part of Muizon, Christian de, Billet, Guillaume & Ladev��ze, Sandrine, 2019, New remains of kollpaniine " condylarths " (Panameriungulata) from the early Palaeocene of Bolivia shed light on hypocone origins and molar proportions among ungulate-like placentals, pp. 841-874 in Geodiversitas 41 (25) on page 856, DOI: 10.5252/geodiversitas2019v41a25, http://zenodo.org/record/3699898, {"references":["MUIZON C. DE & MARSHALL L. G. 1987 - Le plus ancien Condylarthre (Mammalia) sud-americain (Cretace superieur, Bolivie). Compte Rendus hebdomadaires des Seances de l'Academie des Sciences 304: 771 - 774.","MUIZON C. DE & CIFELLI R. L. 2000. - The \" condylarths \" (archaic Ungulata, Mammalia) from the early Palaeocene of Tiupampa (Bolivia): implications on the origin of the South American ungulates. Geodiversitas 22 (1): 47 - 150."]}

Pucanodus gagnieri Muizon & Marshall, 1991 DIAGNOSIS. ��� See Muizon & Cifelli (2000). DESCRIPTION A mandible fragment bearing m2-3 (MHNC 13869) has been referred to Pucanodus gagnieri (Fig. 11) because it presents the mesiodistal compression of the molars especially m3, which is characteristic of that species (Muizon & Marshall 1991). The specimen is approximately of the size of a small Tiuclaenus. The teeth are almost unworn and better illustrate this taxon than the holotype (a mandible with p3-m3), the teeth of which, are notably worn. The massive proportions of the teeth (large width relative to length) and particularly the shortness of the talonid of m3 are conspicuous on this specimen. As in all kollpaniines and North American mioclaenines, the entoconid and hypoconulid are connate (almost confluent) and the talonid basin is an obliquely oriented groove open anterolingually. Measurements are provided on Table 5., Published as part of Muizon, Christian de, Billet, Guillaume & Ladev��ze, Sandrine, 2019, New remains of kollpaniine " condylarths " (Panameriungulata) from the early Palaeocene of Bolivia shed light on hypocone origins and molar proportions among ungulate-like placentals, pp. 841-874 in Geodiversitas 41 (25) on page 856, DOI: 10.5252/geodiversitas2019v41a25, http://zenodo.org/record/3699898, {"references":["MUIZON C. DE & MARSHALL L. G. 1991. - Nouveaux Condylarthres du Paleocene inferieur de Tiupampa (Bolivie). Bulletin du Museum national d'Histoire naturelle, section C, Sciences de la Terre, 4 eme serie, 13: 201 - 225. https: // biodiversitylibrary. org / page / 55803145","MUIZON C. DE & CIFELLI R. L. 2000. - The \" condylarths \" (archaic Ungulata, Mammalia) from the early Palaeocene of Tiupampa (Bolivia): implications on the origin of the South American ungulates. Geodiversitas 22 (1): 47 - 150."]}

Molinodus suarezi Muizon & Marshall, 1987 EMENDED DIAGNOSIS. ��� Size similar to that of Promioclaenus; dental formula I?/3, C?/1, P?/4, M3/3; P3 triangular, with a strong parastyle anterior to paracone; pre- and postparacristae well-developed; protocone is a well-developed cusp and distincly individualized from the paracone but slender with slight pre- and postcingula; P4 more massive, shorter, and wider than P3, with small conules; protocone only slightly larger than on P3 but more massive; wellmarked pre- and postcingula, and strong labial cingulum; M1 triangular and almost symmetrical in relation to its transverse axis; protocone transversely compressed with an oval-shaped apical wear facet; metacone only slightly lingual to the paracone; welldeveloped cingula (pre-, post- and labial); styles slightly to not projected labially; no hypocone; M2 subquadrangular and strongly asymmetrical, with oblique labial edge; well-developed pre- and postcingula, not reaching the para- and metastyles (but close to them); labial cingulum very strong; protocone large, bulbous, and mesiodistally elongated with incipient duplication; conules large; well-developed para- and metacingula reaching para- and metastyles; paracone higher and more voluminous than metacone; metacone much more lingual than paracone; centrocrista straight; para- and metastyles almost aligned with para- and metacones but parastyle still slightly shifted labially; no well-individualized hypocone; M3 much wider than long; strongly bent posteriorly; labial edge strongly oblique; little reduced (i.e. only slightly shorter than M2); metacone and metaconule reduced; i1 and i2 distinctly larger than i3; i2 staggered; lower canine short and robust; p1 single-cusped, single-rooted, and procumbent; p2 triangular in lateral view; transversely flattened; small posterior cusp; p4, much larger; variable in shape from triangular to quadrate, with a large metaconid appressed against protoconid; anterior crest of protoconid possessing a tiny paraconid; large talonid cusp; lower molars with bulbous cusps; trigonid and talonid basin reduced; strong pre- and small postcingulids (on m1 and m3 only); paraconid clearly smaller than and appressed against metaconid; paracristid transverse and arched distally; metaconid distolingual to and slightly smaller than protoconid; cristid obliqua variable in size and reaching labial edge of metaconid; talonid basin small and open lingually (more an oblique groove than a basin); hypoconid large, inflated, circular, and only slightly smaller than protoconid; entoconid and hypoconulid almost completely fused forming a distolingual oblique crest; talonid of m3 larger than on m1-2 with hypoconulid as large as hypoconid. On the dentary presence of a well-developed coronoid crest separated from the labial edge of m3 by a coronoid fossa. Among Tiupampa ���condylarths���, Molinodus more resembles Simoclaenus than the other taxa. However, Molinodus differs from Simoclaenus in its smaller size, its cheek teeth more elongated mesiodistally, its upper molar less transverse, its M2 more asymmetrical with an mesiolabially projected parastyle, its procumbent p1, and its longer rostrum. Molinodus differs from Promioclaenus in its molars, which are more bulbous with apices of the cusps more approximated, in the longer trigonid of the lower molars with a paraconid less appressed against the metaconid, in the presence of a generally distinct labial cingulum, in the non-reduced m3, in the more transverse and less bulbous upper molars, in the thinner postcingulum, in the strong asymmetry of the M2 with an mesiolabially projecting parastyle, and in the unreduced M3. HYPODIGM. ��� As in Muizon & Cifelli (2000) with the additional following specimens: MHNC 13883, a partial left mandible with alveoli of incisors, canine, p1, roots of p2, alveoli of p3 and alveolus of anterior root of p4; MHNC 13867, a partial left mandible with p3-m3; MHNC 13870, a partial left maxilla with M1-M3, with M1 and M2 missing the labial edges of para- and metacones. DESCRIPTION An anterior fragment of left mandible of Molinodus suarezi (Fig. 1) bears the labial edge of the alveoli of the three incisors, the canine, the p1, the roots of p2, the alveoli of p3, and the anterior alveolus of p4 (MHNC 13883). On the medial aspect of the dentary a large symphyseal surface for the intermandibular suture is present. This surface is in one plane with sharp edges, but it is rough and bears numerous ridges and grooves probably interlocking with the symmetrical surface on the other mandible. The two symphyseal surfaces were therefore tightly attached one to the other, but the symphysis was clearly unfused on this specimen. Although ligamentous, it is likely that the symphysis was quite rigid and allowed little intermandibular movements. Because the roots of p3 extends as far as the ventral region of the dentary leaving no space of a potential unerupted tooth germ, we regard that the definitive p3 was erupted. Because the preserved teeth (c and i1) are absolutely unworn, this specimen is interpreted as belonging to a young adult. It is, therefore, not impossible that ontogenetically older individuals may have had a fused symphysis. On the labial side of the dentary a large anterior mental foramen is present ventral to the embrasure between p1 and p2. Although the incisors are missing, the anteriormost region of the dentary is preserved with the labial edge of the incisors alveoli. The dentary is broken vertically in this region and the lingual portion of the alveoli is missing; therefore, a vertical section of the incisors alveoli can be observed. Based on the size of the roots, i1 was apparently the largest of the three incisors or was, at best, similar in size to i2. The i3 is clearly the smallest of the three incisors. Interestingly, the alveolus of i2 presents a distinct lingual shift of its root. As a consequence, the vertical section the alveolus is clearly triangular whereas that of the other alveoli are cylindrical with parallel edges (Fig. 1B, E). This condition of the i2 of Molinodus, is identical to the staggered second incisor, (the i3 according to Hershkovitz 1982, 1995), of many metatherians (e.g., stagodontids, pucadelphyids, sparassodonts, didelphids, microbiotheres, peramelids, thylacinids, dasyurids). The triangular section of the alveolus of the staggered incisor is clearly observed on the figure 5 of Hershkovitz (1982). It is not the first time that a staggered second incisor is described in a eutherian since Hershkovitz (1982: 197) mentions this condition in several extant Carnivora. Among the Tiupampa eutherians, it is absent in Alcidedorbignya inopinata (Muizon et al. 2015), and there is no indication that it was present in Tiuclaenus minutus and Pucanodus gagneri, the only other Tiupampa eutherians that preserve the anterior portion of the dentary. It may be the first time that this trait is observed in a fossil eutherian, but this is probably due to the fact that the anterior portion of the dentary is rarely preserved in fossil mammals. In dorsal view, the three lower incisors are set in a slightly oblique row, relative to the symphyseal plane (Fig. 1C). In other words, i1 is anteromedial to i2, and i3 is posterolateral to i2. The lower incisor tooth row was, therefore, more or less parabolic or V-shaped. The last incisor, i3, was closely appressed against the mesial edge of the canine as indicated by the posi- tion of the i3 alveolus. The canine is a moderately developed tooth but it is robust. The height of the crown (4.60 mm) is approximately twice its mesio-distal length (2.44 mm) at base. The canine is transversely compressed, being distinctly narrower (1.75 mm) at its base than long (2.44 mm). The posterior curvature of the canine is weak and its posterior edge is only very slightly concave. Its mesial edge is distinctly convex. On the mesiolingual edge of the tooth a blunt ridge extends mesioventrally on the dorsal half of the crown and distoventrally on the ventral half (Fig. 1B). In dorsal view, the labial side of the canine is strongly convex, whereas it is almost flat to slightly concave on its lingual side. In labial view the main axis of the crown is moderately oblique in relation to the alveolar plane, with which it forms an angle of approximately 110��. Posterior to the canine is a small p1 separated from the former by a small but distinct diastema. The p1 is single-rooted. It is slightly procumbent and asymmetrical in labial view. The crown of the tooth is markedly compressed transversely. It bears a pronounced mesial crest, which is slightly convex. The distal edge of the tooth is straight and bears a small cuspule at its base (Fig. 1D). There is no cingulum at the base of the crown. The lingual aspect of the crown in markedly concave and its labial edge is convex. As a consequence, in distal view the crown is slightly bent lingually. The roots of p2 are preserved in the dentary of MHNC 13883. The very short diastema, which separates p2 from p1, is approximately twice shorter than the diastema anterior to p1. A similar condition is observed on MHNC 1243, a mandible fragment, which preserves the root of c, the alveolus of p1 and p2 (see Muizon & Cifelli 2000). Interestingly, on MHNC 13883 the roots of p2 are set obliquely in the dentary and the anterior root is mesiolabial to the posterior one. The mesiodistal axis of the tooth is approximately at an angle of 30�� with the anteroposterior axis of the tooth row (from c to p4) (Fig. 1D). Because this condition is not present in MHNC 1243, it could represent a pathological condition or an individual variation in MHNC 13883. Posterior to p2, the alveoli of p3 indicate that the tooth was implanted parallel to the axis of the tooth row. The p2 and p3 were not separated by a diastema and were closely appressed one against the other. A relatively complete left mandible of Molinodus suarezi (MHNC 13867) bears p3-4 and m1-3 (Fig. 2). The most interesting element of this specimen lies in its premolars. The teeth are relatively narrow transversely being c. 30% longer than wide. They are roughly triangular in lateral view and are approximately as high as long. The p3 is slightly more slender than the p4 but both teeth are built on a similar pattern. The mesial edge of p3 bears a sharp crest with a marked angulation on the dorsal third of the crown. The largest cusp of the tooth, the protoconid, is transversely narrow and its lingual edge is slightly concave lingually, in its dorsal region. More ventrally it is inflated and convex. The distolingual angle of the protoconid bears a strong inflation, which reaches the dorsal half of the distal edge of the tooth in lingual view. This structure corresponds to the development of a small metaconid. At the mesial base of the tooth is a small cingulum, which is continuous from the distolabial to distolingual edges of the mesial root. Distally a well-developed talonid cusp forms the base of the crown and extends transversely in a robust and rounded cingulum from the distolabial to the distolingual angle of the tooth. In occlusal view, p3 is distinctly wider distally than mesially. The p4 is slightly longer than the p3. Its mesial edge bears a sharp crest that shifts lingually at mid-height of the crown. There, it forms a small tubercle interpreted as an incipient paraconid. The protoconid is strongly convex labially and flat lingually. On its distolingual edge is a large metaconid. In dorsal view, it is slightly smaller than the protoconid and its apex is distinctly distal to that of the protoconid. On the mesial edge of the protoconid, a sharp and well-developed paracristid connects to the paraconid mesially. Posterior to the trigonid, the talonid does not bear differentiated cusps but forms a thick distobasal ridge, which extends from the mesiolingual to mesiolabial aspects of the distal root. The distal edge of the tooth is slightly wider than the mesial one. The condition of the p4 of MHNC 13867 distinctly departs from the morphology of the isolated p4 (MHNC 1244) referred to Molinodus suarezi by Muizon & Cifelli (2000: fig. 3M, N). On MHNC 1244 the metaconid is almost totally lingual to the protoconid and not shifted distally. Furthermore, the crown of the tooth is markedly more massive, strongly compressed mesiodistally, and more inflated transversely. As a whole, MHNC 1244 more resembles the p4 of Simoclaenus sylvaticus in all its features but is clearly much smaller. When compared to the size of the roots observed on the holotype of S. sylvaticus, it is even too small to be a p3 of and it is also slightly too small to be a p2. In other respects, the large metaconid and the well-developed paraconid and paracristid of MHNC 1244 are more compatible with the morphology generally observed on a p4. Therefore, we think that MHNC 1244 is actually a p4 and that, either, the morphology of the p4 of M. suarezi is highly variable or MNHC 1244 represents a new taxon at Tiupampa. Given the size difference it is unlikely that it could be referred to S. sylvaticus, except if this species is sexually dimorphic, which is unknown yet. However, given the lack of a representative sample of M. suarezi and S. sylvaticus, this uncertainty cannot be resolved so far. The three molars have the characteristic features of Molinodus suarezi as described by Muizon & Cifelli (2000). The trigonid bears a well-developed paraconid but distinctly smaller than the metaconid and placed mesial to it or slightly labial (on m1). The paraconid is closely appressed against the metaconid. The latter is large, almost as large as the protoconid and located distolingual to it. As a consequence, the protocristid is obliquely oriented (mesiolabially-distolingually) as compared to the axis of the tooth row. On m1 and m2 the talonid is slightly narrower than the trigonid. The cristid obliqua extends from the large hypoconid to the central region of the protocristid. Lingually, the hypoconulid and the entoconid are connate and the talonid basin is in fact an obliquely oriented groove that opens mesiolingually as is observed in all kollpaniines. On m3 the hypoconulid is much larger than on the other molars and is as large as the hypoconid. The small size of the m1 relatively to the other molars is noteworthy. This feature is present in all kollpaniines but it is especially pronounced in the holotype (YPFB Pal 6112) of M. suarezi (Muizon & Cifelli 2000: fig. 3A) and MHNC 13867 (Table 1). On the dentary of MHNC 13867, the posteriormost mental foramen is located below the anterior root of p4. The corpus mandibularis of MHNC 13867 and 13871 is relatively massive especially in the latter. On both specimens, most of the ramus mandibularis is missing, except the anterior portion of the coronoid process. In the region of the retromolar space, the anterior basis of the coronoid process is very wide and bears a conspicuous labially opening coronoid fossa. The fossa is much deeper on MHNC 13871 than on 13867. Lateral to the fossa, the coronoid crest is salient and extends ventrally on the lateral aspect of the dentary (Fig.3). This condition indicates a powerful masseter muscle, which inserts in the masseteric fossa and on the coronoid crest and is congruent with the stoutness of the corpus mandibularis. A robust coronoid crest is observed on the other specimens of M. suarezi (YPFB Pal 6114, MHNC 8269) and on the large kollpaniines (Simoclaenus and Andinodus). It is absent or barely present in Tiuclaenus and Pucanodus, which are the smallest kollpaniine taxa (see Muizon & Cifelli 2000). A partial left maxilla referred to Molinodus suarezi (MHNC 13870) bears the three molars and is the first specimen discovered with an M3 associated to the anterior molars (Figs 4; 5; 6). The M3 referred by Muizon & Cifelli (2000: fig. 2, E) to M. suarezi is an isolated specimen and its referral had yet to be confirmed. M1 and M2 of MHNC 13870 are incomplete and are missing most of the labial edges of the para- and metacones and all the stylar regions and labial cingulum. M3 of MHNC 13870 is complete. M1 and M2 of MHNC 13870 preserve the lingual half of the tooth. The large protocone bears large conules which are similar to those already described in Molinodus. The mesial and distal edges of M1-2 present well-developed pre- and postcingulae, which extended labially until the stylar area of the teeth. The most interesting cusp of this specimen is the protocone. On M1-2 as is observed on the molars of M. suarezi described by Muizon & Cifelli (2000), the protocone is mesiodistally elongated and its wear facet is markedly ovale-shaped. On the M2 of MHNC 13870, the wear facet is constricted and the protocone bears vertical grooves, which reach the apex of the cusp. As a consequence, the latter is distinctly bilobate (Fig. 5). The posterior lobe of the protocone of MHNC 13870 receives the postprotocrista, which links it to the metaconule. This bilobate condition is even more pronounced than in MHNC 8280 (Muizon & Cifelli 2000: fig. 2A) as it concerns more than the apex of the cusp and extends dorsally on the protocone. It indicates that the duplication of the apical region of the protocone was almost certainly observable on the dentine at the enamel-dentine joint (see Anemone et al. 2012). The M3 of MHNC 13870 is remarkably similar to the isolated tooth referred to Molinodus suarezi by Muizon & Cifelli (2000) and does not require further description., Published as part of Muizon, Christian de, Billet, Guillaume & Ladev��ze, Sandrine, 2019, New remains of kollpaniine " condylarths " (Panameriungulata) from the early Palaeocene of Bolivia shed light on hypocone origins and molar proportions among ungulate-like placentals, pp. 841-874 in Geodiversitas 41 (25) on pages 844-851, DOI: 10.5252/geodiversitas2019v41a25, http://zenodo.org/record/3699898, {"references":["MUIZON C. DE & MARSHALL L. G. 1987 - Le plus ancien Condylarthre (Mammalia) sud-americain (Cretace superieur, Bolivie). Compte Rendus hebdomadaires des Seances de l'Academie des Sciences 304: 771 - 774.","MUIZON C. DE & CIFELLI R. L. 2000. - The \" condylarths \" (archaic Ungulata, Mammalia) from the early Palaeocene of Tiupampa (Bolivia): implications on the origin of the South American ungulates. Geodiversitas 22 (1): 47 - 150.","HERSHKOVITZ P. 1982. - The staggered marsupial lower third incisor (i 3). Geobios, memoire special, 6: 191 - 200. https: // doi. org / 10.1016 / S 0016 - 6995 (82) 80113 - 7","HERSHKOVITZ P. 1995. - The staggered marsupial lower incisor: hallmark of cohort Didelphimorphia. and description of a new genus and species with staggered i 3 from the Albian (Lower Cretaceous) of Texas. Bonner Zoologische Beitrage 45 (3 - 4): 153 - 169. https: // biodiversitylibrary. org / page / 44799597","MUIZON C. DE, BILLET G., ARGOT C., LADEVEZE S. & GOUSSARD F. 2015. - Alcidedorbignya inopinata, a basal pantodont (Eutheria, Mammalia) from the early Palaeocene of Bolivia: anatomy, phylogeny, and palaeobiology. Geodiversitas 37 (4): 397 - 634. https: // doi. org / 10.5252 / g 2015 n 4 a 1","ANEMONE R. L., SKINNER M. M. & DIRKS W. 2012. - Are there two distinct types of hypocone in Eocene primates? The ' pseudohypocone' of notharctines revisited. Palaeontologia electronica 15 (3): 26 A, 13 p."]}

Tiuclaenus robustus Muizon & Cifelli, 2000 DIAGNOSIS. ��� See Muizon & Cifelli (2000). DESCRIPTION A right mandible fragment bearing m2-3 (MHNC 13875) has been referred to Tiuclaenus robustus (Fig. 10B, C) essentially because, although structurally similar to the other species of Tiuclaenus (T. minutus and T. cotasi), it differs from them in its size, distinctly larger, and in its greater massiveness. Furthermore, as is observed on the holotype (a mandible fragment with m2-m3, MHNC 1233), m3 of MHNC 13875 is proportionally shorter than in T. minutus and T. cotasi being barely longer than m2. An interesting feature of this specimen is the morphology of the roots of m2 and m3, which are long extending ventrally on more than 2.5 the height of the crown (Fig. 10C). Furthermore, the apices of the roots are markedly splayed with their posterior edges extending posteriorly, providing the extremity of the root a characteristic hammer-shape. Although the ventral edge of the dentary is partly broken, this morphology gives the impression that the root had to develop posteriorly because it was abutting the ventral edge of the mandibular canal., Published as part of Muizon, Christian de, Billet, Guillaume & Ladev��ze, Sandrine, 2019, New remains of kollpaniine " condylarths " (Panameriungulata) from the early Palaeocene of Bolivia shed light on hypocone origins and molar proportions among ungulate-like placentals, pp. 841-874 in Geodiversitas 41 (25) on page 856, DOI: 10.5252/geodiversitas2019v41a25, http://zenodo.org/record/3699898, {"references":["MUIZON C. DE & CIFELLI R. L. 2000. - The \" condylarths \" (archaic Ungulata, Mammalia) from the early Palaeocene of Tiupampa (Bolivia): implications on the origin of the South American ungulates. Geodiversitas 22 (1): 47 - 150."]}

International audience

International audience

International audience; The description of new specimens of kollpaniines “condylarths” from Tiupampa (early Palaeocene of Bolivia) represents a significant addition to the knowledge of the earliest fauna of South American ungulates. Several partial mandibles and maxillae of Molinodus suarezi and Simoclaenus sylvaticus are described. The morphology of the lower premolars of Molinodus, being associated to lower molars, is established and a previous referral of an isolated p4 is rejected. A maxilla of Simoclaenus reveals the morphology of the so far unknown P1-4 of this taxon and allows a discussion on the development of the protocone in Palaeocene “condylarths”. The subvertical maxilla-premaxilla suture and the vertical implantation of the P1/p1 confirm the shortness of the snout of Simoclaenus, whereas the procumbency of the p1 of Molinodus indicates a longer rostrum. The upper molars of Molinodus confirm the presence of a tendency to duplication of the protocone, which is regarded as the incipient development of a pseudohypocone. The various patterns of formation of a hypocone (or pseudohypocone) are considered and, among other South American Native Ungulates, a protocone-derived pseudohypocone (i.e. Molinodus-like) is hypothesized in Lamegoia, Raulvaccia, and notoungulates, whereas a postcingulum-derived, hypocone is present in didolodontids and litopterns.The new specimens confirm the conspicuous small size of the M1/m1 of Molinodus and Simoclaenus as compared to the M2/m2. Consequently, we examined the relative proportions of molars in these taxa as compared to a variety of extant and extinct euungulates. Their proportions were plotted into the ‘developmental’ morphospace based on the predictive mathematical model of Kavanagh et al. (2007) (Inhibitory Cascade Model, or IC model), which might explain a large part of the mammalian diversity in molar proportions. Based on the upper molars, the Tiupampa kollpaniines were retrieved in a separate area of the predicted morphospace with other North American “condylarths” with large M2; this departure is also consistent with previous results concerning the lower molars (large m2). These peculiar molar proportions were found distinct from many other mammals, and might represent clade-specific differences: the large size of both the upper and lower second molars relative to other molars thus possibly representing a derived character state shared by some “condylarths” and kollpaniines.; La description de nouveaux spécimens de «condylarthres» kollpaniinés de Tiupampa (Paléocène inférieur de Bolivie) constitue un complément d’information significatif à la connaissance de la plus ancienne faune d’ongulés sud-américains. Plusieurs mandibules et maxillaires partiels de Molinodus suarezi et Simoclaenus sylvaticus sont décrits. La morphologie des prémolaires inférieures de Molinodus, étant associées à des molaires, est établie et l’attribution antérieure d’une p4 isolée à ce taxon est rejetée. Un maxillaire de Simoclaenus révèle la morphologie, inconnue auparavant, des P1-4 de ce taxon et permet une discussion sur le développement du protocone des prémolaires chez des « condylarthres» du Paléocène. La suture maxillaire-prémaxillaire, subverticale, et l’implantation verticale des P1/p1 confirme la faible longueur du museau de Simoclaenus, tandis que la p1 de Molinodus, légèrement proclive, indique un rostre plus long. Les molaires supérieures de Molinodus confirment la présence d’une tendance la duplication du protocone qui est considérée comme le développement initial d’un pseudohypocone. Les modalités de formation d’un hypocone (ou pseudohypocone) sont considérées et, parmi les autres ongulés natifs sud-américains, l’hypothèse de la formation d’un pseudohypocone, dérivé du protocone (de type Molinodus), est proposée chez Lamegoia, Raulvaccia et les notongulés, tandis qu’un vrai hypocone, dérivé du postcingulum, est présent chez les didolodontes et les litopternes.Les nouveaux spécimens confirment la petite taille des M1/m1 de Molinodus et Simoclaenus par rapport aux M2/m2. Les proportions relatives des molaires ont donc été examinées chez ces taxons et comparées à plusieurs euongulés actuels et fossiles. Leurs proportions ont été reportées sur un graphe dans l’espace morphologique de développement fondé sur le modèle mathématique prédictif de Kavanagh et al. (2007) (Inhibitory Cascade Model), qui pourrait expliquer une grande partie de la diversité des proportions des molaires de mammifères. Sur la base des molaires supérieures, les kollpaniinés de Tiupampa se situent dans une aire séparée de l’espace morphologique prédit, et ce, avec d’autres « condylarthres» nord-américains (possédant une grande M2). Cet écart est consistant avec les résultats antérieurs concernant les molaires inférieures (grandes m2). Ces proportions particulières sont différentes de celles de nombreux autres mammifères et pourrait représenter une spécificité de clade concernant les tailles relatives des molaires : la grande taille des deuxièmes molaires supérieures et inférieures pourrait donc constituer un caractère dérivé partagé par certains « condylarthres» et les kollpaniinés.

International audience; The rodent record during the late Eocene – early Oligocene interval is poorly known in South America. Our team’s recentfieldwork in Peruvian Amazonia allowed for the discovery of five new fossil-bearing localities in a single stratigraphic sectionat Shapaja (Tarapoto area, San Martín Department), considered as early Oligocene by mammalian biostratigraphy. Here, wedescribe the caviomorph material from Shapaja, which documents 17 distinct taxa (with the co-occurrence of four to sevencaviomorph taxa in a single level) representing at least three of the four extant superfamilies. Eight taxa are new to science:Kichkasteiromys raimondii nov. gen. et sp. and Shapajamys labocensis nov. gen. et sp. (Erethizontoidea), Selvamys paulus nov.gen. et sp. and Mayomys confluens nov. gen. et sp. (Octodontoidea), Eoincamys valverdei nov. sp. and E. parvus nov. sp. (?Chinchilloidea),and Tarapotomys subandinus nov. gen. et sp. and T. mayoensis nov. gen. et sp. (superfamily indet.). These diversifiedcaviomorph faunas constitute the most equatorial Paleogene record of this group. The taxa from Shapaja are not documentedin other low-, mid- and high-latitudes Paleogene localities, except for Eoincamys. This genus is otherwise only found at SantaRosa (Peruvian Amazonia, ?late Eocene/early Oligocene), thereby indicating a close temporal window for the Shapaja localities.

Additional Results and Discussion

Through phenotypic plasticity, bones can change in structure and morphology, in response to physiological and biomechanical influences over the course of individual life. Changes in bones also occur in evolution as functional adaptations to the environment. In this study, we report on the evolution of bone mass increase (BMI) that occurred in the postcranium and skull of extinct aquatic sloths. Although non-pathological BMI in postcranial skeleton has been known in aquatic mammals, we here document general BMI in the skull for the first time. We present the evidence of thickening of the nasal turbinates, nasal septum and cribriform plate, and further thickening of the frontals, and infilling of sinus spaces by compact bone in the late and more aquatic species of the extinct sloth Thalassocnus. Systemic bone mass increase occurred among the successively more aquatic species of Thalassocnus, as an evolutionary adaptation to the lineage's changing environment. The newly documented pachyostotic turbinates appear to have conferred little or no functional advantage and are here hypothesized as a correlation with or consequence of the systemic BMI among Thalassocnus species. This could, in turn, be consistent with a genetic accommodation of a physiological adjustment to a change of environment.

Supplementary material and methods, and results concerning the alternative models tested

Additional Material and Methods

Data relative to reduced major axis analyses showing comparisons of indices between IC model and regressions in hypsodont and hypselodont Mesotheriidae and Ctenodactylidae.

International audience; The orientation of the semicircular canals of the inner ear in the skull of vertebrates is one of the determinants of the capacity of this system to detect a given rotational movement of the head. Past functional studies on the spatial orientation of the semicircular canals essentially focused on the lateral semicircular canal (LSC), which is supposedly held close to horizontal during rest and/or alert behaviors. However, they generally investigated this feature in only a few and distantly related taxa. Based on 3D-models reconstructed from µCT-scans of skulls, we examined the diversity of orientations of the LSC within one of the four major clades of placental mammals, that is, the superorder Xenarthra, with a data set that includes almost all extant genera and two extinct taxa. We observed a wide diversity of LSC orientations relative to the basicranium at both intraspecific and interspecific scales. The estimated phylogenetic imprint on the orientation of the LSC was significant but rather low within the superorder, though some phylogenetic conservatism was detected for armadillos that were characterized by a strongly tilted LSC. A convergence between extant suspensory sloths was also detected, both genera showing a weakly tilted LSC. Our preliminary analysis of usual head posture in extant xenarthrans based on photographs of living animals further revealed that the LSC orientation in armadillos is congruent with a strongly nose-down head posture. It also portrayed a more complex situation for sloths and anteaters. Finally, we also demonstrate that the conformation of the cranial vault and nuchal crests as well as the orientation of the posterior part of the petrosal may covary with the LSC orientation in Xenarthra. Possible inferences for the head postures of extinct xenarthrans such as giant ground sloths are discussed in the light of these results.

Upper and lower occlusal dental patterns of extant Ctenodactylidae.

Test of correlation between dental area and occlusal complexity.

Trachytherus ramirezi sp. nov. Figs. 2, 3, 4, & 5 Synonyms. Trachytherus sp. (Shockey et al. 2006: p. 206 & fig. 2); Trachytherus sp. ���mid-sized species��� or ���medium size species��� (Shockey et al. 2009: pp. 18, 20, fig. 1 C & 8 B, table 5). Holotype. MUSM 350; nearly complete cranium with jaws preserving all of the teeth except right I 3 ���C, left I 2���3; the missing p 2 may have been lost during the life of the animal; see Discussion). The holotype was discovered by RSG near the summit of Pan de Az��car, in the Upper Moquegua formation in August, 2002. Referred specimens. MUSM 963, partial right manus, including distal radius and ulna, cuneiform, lunar, unciform, and magnum, along with proximal Mc II���V; MUSM 961, right astragalus; MUSM 962, right astragalus; MUSM 966, right astragalus. Occurrence. Trachytherus ramirezi is only known from near the summit of Pan de Az��car (elevation 1,663 m), located at S 17 �� 13.100 ���, W 71 �� 0.665 ���, nine km WSW of the city of Moquegua, Peru, in the Departamento de Moquegua. The holotype (MUSM 350) and all the referred specimens were collected within the upper Moquegua Formation, from about 10 to 20 meters below the summit of Pan de Az��car, likely (but not certainly) above the level of the Sugarloaf Ash (the specimens were buried in weathered sediments that obscured their precise stratigraphic context). Etymology. The specific name, ramirezi, is a tribute to our late colleague and friend, Gregorio Ram��rez Andrade, who helped excavate the holotype and provided essential help in the field at Moquegua and in the lab at MUSM during his all too brief tenure there. Diagnosis. Relatively small non-mesotheriine (���trachytheriine���) mesotheriid with incisive foramina being parallel, rather than having a triangular or ���heart-shaped��� form, typical of mesotheriids; enlarged molars (M 1���3 occupy> 2 / 3 of the mesiodistal length of the cheektooth row in mature adult); M 1���2 with transverse dimensions nearly twice that of the preceding premolars; upper canine retained and larger than I 3; unique pattern of central fossettes co-occurrence on upper cheek teeth, that is, well-isolated central fossettes co-occuring on P 3���4 and M 2��� 3. A B 3 cm m 1 Trachytherus ramirezi differs from T. subandinus by upper molars with much greater transverse dimensions, relatively small premolars, relatively smoother ectolophs of cheekteeth, M 1 that forms roots and is lower crowned; and closed fossettes co-occurring on P 3���4 and M 2���3, whereas the lingual apertures of M 2���3 remain open in T. subandinus when P 3���4 have closed and almost disappearing fossettes. Differs from T. spegazzinianus and T. alloxus, by presence of upper canine (usually absent in mature specimens of T. alloxus); greater difference in size and form between upper premolars and molars; M 1 hypsodont (not hypselodont as generally occurs in T. alloxus); closed fossettes co-occurring on P 3���4 and M 2���3 (see description for a detailed comparison on this aspect); and presence of well-developed suprameatal fossa. Description. Trachytherus ramirezi is a relatively small mesotheriid, smaller than T. alloxus, as evidenced by the palatal length of 100 mm of the holotype of T. ramirezi, whereas sampled specimens of T. alloxus from Salla (n= 8) had a mean of 121 mm and ranged from 111���126 mm (Shockey et al. 2006; see also Billet and Martin, 2011). Astragali referred to T. ramirezi also are distinctly smaller and fall outside the range of those referred to T. alloxus (Fig. 5). Upper Dentitions. The holotype has gliriform incisors, hypsodont and rooted premolars, M 1 hypsodont and rooted, and M 2���3 euhypsodont and apparently hypselodont. The dental formula is 3 /2, 1/0, 3/3, 3/ 3. As generally occurs in other known mesotheriids, the teeth are covered with cementum. The upper series is essentially closed, save for the small sizes of I 2 ���C, which, due to their diminutive form, leave small gaps between them (Fig. 3 A). As is typical for Trachytherus, and mesotheriids in general, the I 1 is broad and strongly curved, though that of T. ramirezi is neither as broad or as curved as those of T. spegazzinianus or T. alloxus. Enamel covers the I 1 labial surface, whereas it is lacking from the lingual side. The lingual surface of I 1 occludes with the tip of the crown of the procumbent lower incisors (i 1���2), resulting in uneven wear on I 1 (Fig. 2 A & B). The more durable enamel on the labial surface also likely contributed to the uneven wear. I 2 is much smaller than I 1, being little more than a peg-like cylinder, subcircular in cross section, and with a crown height T. alloxus (Billet et al. 2008), an upper canine is present and is larger than I 3. It is slightly spatulate and curved, having a concave lingual surface and convex labial surface. The canine is slightly procumbent, with the tip of the crown lying further from the P 2 than the base of the tooth. The holotype does not have a P 1 (or retained dP 1). The P 2 is much smaller than the remaining premolars. Like the other upper premolars, the transverse dimension is greater than the distal-mesial dimension. The ectoloph of P 2 forms a gentle curve in occlusal view, lacking any distinctive convolutions aside from a subtle, blunt paracone ridge. The lingual border is slightly more curved than is the ectoloph. The tooth is worn such that there is no fossette. P 3 and P 4 are similar to P 2, but they are progressively larger and each retains a small oval fossette that has an obliquely oriented long axis. There is a marked size discontinuity between the premolars and the much larger molars, exceeding that observed in any ontogenetic/wear stage of T. spegazzinianus, T. alloxus, or T. subandinum. M 1 is heavily worn, leaving no trace of a fossette, and its transverse dimension is greater than the mesiodistal, as in heavily worn M 1 of T. alloxus (Billet et al., 2008: Appendix 3). M 1 is conspicuously lower crowned than M 2���3, and unlike the M 2���3 it has closed roots (Fig. 2 B). Enamel is absent from the lingual and posterior borders of the tooth. The parastyle of M 2 slightly overlaps the M 1. The M 2 is less worn and much higher crowned than the M 1 and, unlike M 1, is openrooted. It retains an oblique central fossette, which presumably resulted with the basal union of protoloph with a metaloph/posterior cingulum as occurs in T. spegazzinanus and T. alloxus (Billet et al., 2008). Like the M 1, the lingual and posterior borders lack enamel. M 3 differs from M 1���2 by having a distinct metastyle that contributes to the greater mesiodistal dimension of the tooth, resulting in this dimension greater than the transverse (note that the M 3 of T. alloxus, contrarily to M 1���2, also has a greater mesiodistal diameter than the transverse one, at all stages; Billet et al. 2008). It is fully erupted, as evidenced by wear of the posterior occlusal surface. This posterior border has no enamel, but enamel is present on the lingual side as well as the mesial and labial borders of the tooth. Central fossettes on the P 3���4 and M 2���3 of the type are contemporaneous. This is in stark contrast with T. spegazzinianus, which loses the central fossettes of P 3���4 well before the central fossettes of M 2���3 are formed (FMNH P 13281, UNPSJB PV 112). The pattern exhibited by T. subandinus is also close to that of T. spegazzinianus in contrast to the form of T. ramirezi. Indeed, the central fossettes of P 3���4 are very small (thus close to disappearance; see Billet et al., 2008) in the unique specimen of T. subandinus while M 2���3 are far removed from isolating a central fossette (a stage possibly never attained for M 2���3 in this species; Villarroel et al., 1994 p 29); thus the central fossette probably disappears from P 3���4 before being isolated on M 2���3 in T. subandinus. The situation in T. alloxus is rather intermediate as it barely loses the central fossettes of P 3���4 before the central fossettes are isolated on both M 2 and M 3 (see diagnosis above and Billet et al. 2008: Appendix 2: stages 12-13 - 14; MNHN-Bol-V 0 0 5011 and 003478). Mandible and Lower Dentitions. The mandible is fairly complete, except for the ascending rami, which were badly crushed (Fig. 2 B). One of the mandibular condyles was preserved and its long axis (transverse dimension) is 21 mm. The jaw is smaller and more gracile than that of T. alloxus. Likely indicative of its late ontogenetic age, the molars of the holotype are quite large relative to the premolars, occupying about 70 % of the cheektooth length (Fig. 3 B; Table 2). The incisors (i 1���2) are columnar, procumbent, and relatively and absolutely thinner than those of T. alloxus. The wear surface of i 1 is flat and perpendicular to the long axis of the tooth, whereas i 2 shows significant wear on its lingual surface from occlusion with I 2. There is no sign of either a canine or first premolar (neither dp 1 or p 1). The p 2 is lost from both sides, but the shallow alveoli remaining on each side indicate that a single-rooted tooth was present and smaller than the remaining premolars. These posterior premolars (p 3���4) are high crowned, but very small relative to the molars. Both p 3 s show significant wear; the trigonid/talonid fossettid had worn away on the left p 3, but a minute part remains on the lingual side of the right p 3. This tooth is nearly rectangular in occlusal outline, with just a barely discernable sulcus demarcating the trigonid and talonid boundary. The mesiodistal dimension of the tooth is greatest at the occlusal level and tapers ventrally nearly to a point at the root such that the length of the occlusal surface decreases with wear (the opposite is true of m 3). The p 4 has a more distinctive trigonid/talonid fossettid, which lies close to the lingual border of the tooth. The p 4 trigonid is slightly larger than the talonid. The m 1 has an asymmetric figure-eight shape in occlusal view, with the talonid being longer and wider than the trigonid. The vertical groove of the labial sulcus is better defined than those of the premolars. The m 1 has significant wear, lacking any hint of a trigonid/talonid fossettid. The m 2 is larger than m 1. Consistent with its later eruption, it shows less wear, as evidenced by the presence of the trigonid/talonid fossettid. The m 3 is the largest molar and has a similar form as m 2, except that the talonid is longer and extends distally to a point, whereas m 1���2 have blunt posterior ends. The base of the m 3 talonid extends beyond the terminal border of the occlusal surface, indicating that the total length of the tooth would increase with continued wear. Skull. The area containing the incisive foramina does not present the typical triangular (heart-shaped) outline observed in mesotheriids by Billet et al. (2008); in T. ramirezi, the distal end of these foramina is not pointed and the lateral border of each foramen is more parallel to its medial border than it is in T. alloxus and other mesotheriids. The maxillae overlap the nasals, as occurs in other mesotheres and a few other typotheres (e.g., Protypotherium AMNH 9226; Hegetotherium AMNH 9501). The nasal/frontal sutures are at the level of the anterior margin of the orbits and the nasals extend anteriorly such that they overlap the nasal aperture. The frontals have well developed triangular postorbital processes that define the dorsoposterior region of the orbit. These do not reach the zygomatic arch, leaving a gap of over 1 cm. The long axis of the glenoid fossa is transversely oriented, but slightly oblique, with its lateral margin projecting slightly anterior to the medial edge. Its long axis has a dimension of 24.4 mm. The post glenoid process is robust and abuts a distinctive descending crest of the auditory meatus, the ���crista meatus��� of Patterson (1934) and subsequent workers (Fig. 2 A���). The contact of the postglenoid process and crista meatus is unlike the condition seen in Pseudotypotherium (Patterson, 1934:fig. 8), Mesotherium (e.g., AMNH 14965), or some specimens of T. alloxus (e.g., UF 91933), in which there is a significant gap between the crista meatus and postglenoid process. The crista meatus appears to be shorter than those of other mesotheres, but breakage obscures its complete form. A suprameatal fossa defines the dorsal boundary between the postglenoid process and the dorsal region of the external auditory meatus. An associated foramen is superficial to the deep part of the fossa, and lies in the same position as the suprameatal foramen of the leontiniid notoungulates, Ancylocoelus (Gabbert, 2004: fig. 14.2) and the mesotheriid T. alloxus (Billet et al., 2008: 163). The retrotympanic (or posttympanic) process of the squamosal is small, much shorter than the crista meatus. The posterior portion of the external auditory meatus lies at the posterolateral border of the skull. Breakage at the dorso-posterior region of the skull reveals a hollow epitympanic sinus (visible in Fig. 2 C). grooves for D A cf. Trachytherus 40 spegazzinianus 35 T. alloxus L total 30 T. ramirezi Indet. taxon 25 of Moquegua 20 10 12 14 16 18 20 22 Wtrochlear W B fib f cot f troch troch ppa (tib f) L total tib stop fg nav f fib f ect f ppa sus 1 cm f nav f T. ramirezi T. alloxus cf. T. spegazzinianus The paroccipital process is broken and the occipital condyles are missing. The basisphenoid and sphenoid were recovered, but we are unable to connect these to the rest of the skull due to damage. This damage and missing pieces also makes it impossible to observe the ventral foramina. The braincase is not large, its broadest dimension being distinctively less than the width reached by the postorbital process of the frontals. A sagittal crest is present, its modest size exaggerated by the smallness of the braincase it overlies. Postcranial Elements. A variety of postcranial elements of Trachytherus were found alongside the holotype skull as well as an m 3 of a different individual of T. ramirezi. They apparently do not represent the same individual as the type since they appear to be from ontogenetically young individuals, whereas the dentitions of the holotype are heavily worn, suggestive of a more advanced ontogenetic age. Of these elements, we refer the partial manus of MUSM 963 (Fig. 4 A), as well as some tarsals found near the holotype, to T. ramirezi. A smaller mesothere manus (MUSM 968; Fig 4 B) may also pertain to T. ramirezi, but we do not refer it to this taxon since it is so small that it may represent a different species. The manus of Trachytherus ramirezi (MUSM 963; Fig 4 A) is similar to that of cf. T. spegazzinianus from Cerro Mono of Moquegua (Fig. 4 C; Shockey et al. 2009: fig. 1g [map] for locality) and T. alloxus from Salla (Fig. 4 D). We note the unfused epiphyses of the distal radius of the specimen referred to T. ramirezi (Fig. 4 A) that indicates its relatively young ontogenetic age. The form of the carpals of T. ramirezi is nearly identical to those of T. spegazzinianus, T. alloxus, and the small indeterminate species (Figs. 4), save for being intermediate in size; i.e., larger than the diminutive MUSM 965 and smaller than both those of cf. T. spegazzinianus and T. alloxus (Fig. 4). Where known, mesotheriid hands are pentadactyl, however, since neither the Mc I nor trapezoid of T. ramirezi were recovered, we cannot assert that it also was pentadactyl. (Note, even the geologically younger, Pleistocene Mesotherium had five digits on its manus [Serres 1867; Ameghino 1891].) Astragali referred to T. ramirezi (MUSM 961, 962, and 966) are like those of known mesotheriids, having assymetric trochlea (lateral trochlear ridge much larger than the medial), a separate groove for the flexor hallucis longus (suggestive of a pentadactyl manus), distinct constricted neck (though not greatly elongated) and a well developed medial process (Fig. 5; see also Shockey et al. 2007, 2009). The referral of these specimens specifically to T. ramirezi was based primarily upon size; i.e., they include the larger astragali from Cerro Pan de Az��car, which are distinctly smaller than the one associated with the partial skeleton of cf. T. spegazzinianus (MUSM 668) from Cerro Mono (Table 2; Fig. 5). Due to our uncertainty of the alpha taxonomy of mesotheriid postcranial specimens that are discontinuously smaller than those referred to T. ramirezi, we did not refer the diminutive astragalus (MUSM 967) or a partial manus (MUSM 965) of Pan de Az��car to that, or any, taxon. These remain as an indeterminate small taxon., Published as part of Shockey, Bruce J., Billet, Guillaume & Salas-Gismondi, Rodolfo, 2016, A new species of Trachytherus (Notoungulata: Mesotheriidae) from the late Oligocene (Deseadan) of Southern Peru and the middle latitude diversification of early diverging mesotheriids, pp. 565-583 in Zootaxa 4111 (5) on pages 568-574, DOI: 10.11646/zootaxa.4111.5.3, http://zenodo.org/record/262179, {"references":["Shockey, B. J., Salas, R., Quispe, R., Flores, A., Sargis, E. J., Acosta, J., Pino, A., Jarica, N. J. & Urbino, M. (2006) Discovery of Deseadan fossils in the Upper Moquegua Formation (late Oligocene -? early Miocene) of Southern Peru. Journal of Vertebrate Paleontology, 26 (1), 205 - 208. http: // dx. doi. org / 10.1671 / 0272 - 4634 (2006) 26 [205: DODFIT] 2.0. CO; 2","Shockey, B. J., Salas Gismondi, R., Gans, P., Jeong, A. & Flynn, J. J. (2009) Paleontology and Geochronology of the Deseadan (late Oligocene) of Moquegua, Peru. American Museum of Natural History Novitates, 3668, 1 - 24. http: // dx. doi. org / 10.1206 / 662.1","Billet, G. & Martin, T. (2011) No evidence for an afrotherian-like delayed dental eruption in South American notoungulates. Naturwissenschaften, 98, 509 - 517. http: // dx. doi. org / 10.1007 / s 00114 - 011 - 0795 - y","Billet, G., de Muizon, C. & Mamani, B. (2008) Late Oligocene mesotheriids (Mammalia, Notoungulata) from Salla and Lacayani (Bolivia): implications for basal mesotheriid phylogeny and distribution. Zoological Journal of the Linnean Society, 152, 153 - 200. http: // dx. doi. org / 10.1111 / j. 1096 - 3642.2007.00388. x","Villarroel, C., Sempere, T. & Marshall, L. G. (1994) Un nuevo Trachytherus (Notoungulata, Mammalia) en el Terciario de la faja subandina norte de Bolivia. In: Congreso Geologico de Bolivia, Memorias. Vol. 9. Santa Cruz, Bolivia, pp. 28 - 32.","Patterson, B. (1934) Trachytherus, a typotherid from the Deseado beds of Patagonia. Field Museum of Natural History, Geological Series, 6, 119 - 139.","Gabbert, S. L. (2004) The basicranial and posterior cranial anatomy of the families of the Toxodontia. Bulletin of the American Museum of Natural History, 285, 177 - 190. http: // dx. doi. org / 10.1206 / 0003 - 0090 (2004) 285 % 3 C 0177: C % 3 E 2.0. CO; 2","Serres, M. (1867) De l'osteographie du Mesotherium et de ses affinities zoologiques. Comptes Rendus de l'Academie des Sciences, Paris, 65, 6 - 7, 140 - 148, 273 - 278, 429 - 437, 593 - 599, 740 - 748, 841 - 848.","Ameghino, F. (1891) Los monos fosiles del Eoceno de la Republica Argentina. Revista Argentina de Historia Natural, 1, 383 - 397.","Shockey, B. J., Croft, D. A. & Anaya, F. (2007) Analysis of function in absence of extant functional homologues: a case study using mesotheriid notoungulates (Mammalia). Paleobiology, 33 (2), 227 - 247. http: // dx. doi. org / 10.1666 / 05052.1"]}

Shockey, Bruce J., Billet, Guillaume, Salas-Gismondi, Rodolfo (2016): A new species of Trachytherus (Notoungulata: Mesotheriidae) from the late Oligocene (Deseadan) of Southern Peru and the middle latitude diversification of early diverging mesotheriids. Zootaxa 4111 (5): 565-583, DOI: http://doi.org/10.11646/zootaxa.4111.5.3

Genus Alcidedorbignya Muizon & Marshall, 1987 TYPE SPECIES. — Alcidedorbignya inopinata. DIAGNOSIS. — Because the genus is monospecific, its diagnosis is that of the type species., Published as part of Muizon, Christian de, Billet, Guillaume, Argot, Christine, Ladevèze, Sandrine & Goussard, Florent, 2015, Alcidedorbignya inopinata, a basal pantodont (Placentalia, Mammalia) from the early Palaeocene of Bolivia: anatomy, phylogeny and palaeobiology, pp. 397-634 in Geodiversitas 37 (4) on page 410, DOI: 10.5252/g2015n4a1, http://zenodo.org/record/5210632

Alcidedorbignya inopinata Muizon & Marshall, 1987 Alcidedorbignya inopinata Muizon & Marshall, 1987c: 205. HOLOTYPE. — A partial maxilla with P4-M3 (YPFB Pal 6121). HYPODIGM. — The hypodigm is that given in Muizon & Marshall (1992), to which we add the following specimens: MHNC 8372, an almost complete skeleton, which is missing only the left upper incisors, the two i1s, a few phalanges and some carpal and tarsal bones and a few caudal vertebrae; MHNC 8373, a partial skull with complete braincase and mandibles of a very young individual, possibly a near-term foetus or a new-born individual (some postcranial elements are preserved); MHNC 8399, a partial skull with the braincase and basicranium perfectly preserved; the rostrum has been partly weathered and part of the left maxilla and the dorsal bones of the rostrum are missing; the right maxilla and premaxilla and the dentaries are almost complete; the specimen also includes half of the atlas; MHNC 8416, a partial skull (with crushed basicranium but the two petrosals well-preserved) and mandibles of a juvenile individual, with a partial right limb, and some ribs; MHNC 8423 a partial skull and mandibles of a juvenile missing part of the occipital region and bearing right dC, erupting P1s, DP2s-DP4s, erupting M1s; di2s, right di3, dcs, p1s in crypt, dp2s-dp4s, and erupting m1s; MHNC 8400, a left maxilla (with C-M3) with jugal and lacrimal; MHNC 8401 a right maxilla with roots of C-P2 and P3-M3; MHNC 8402, associated left maxilla and dentary, with P1-M3 and p3-m3; MHNC 8403, associated right maxilla and dentary, with C-M3 and right i2-trigonid of m3 and left i1-C; MHNC 8404, left maxilla with P3-M3; MHNC 8405, left maxilla with root of canine and P1-M3; MHNC 8406 left maxilla with root of P2 and P3-M3; MHNC 8407, left maxilla with roots of P4, partial M1 and M2-M3; MHNC 8408, maxilla with P4-M1 and partial M2; MHNC 8409, right dentary with c-m3, MHNC 8410, fragment of left dentary with trigonid of m2 and m3; MHNC 8411, fragment of right dentary with m2-m3; MHNC 8412, fragment of right dentary with m2-m3; MHNC 8413, fragment of left dentary with talonid of m2 and m3; MHNC 8414, left dentary with roots of p3-m1 and weathered m2-m3; MHNC 8415, m3; MHNC 8359; right periotic; MHNC 8360, left periotic; MHNC 8361, right periotic; MHNC 8362, left periotic; MHNC 8419, right periotic; MHNC 8420, right periotic; MHNC 8421, left periotic; MHNC 8422, right periotic (pars cochlearis); MHNC 8423, a sub-complete skull and mandibles of a juvenile, missing most of the occipital and the premaxillae. GEOLOGICAL SETTING AND AGE. — The Tiupampa mammals occur in the middle section of the Santa Lucia Formation (Marshall et al. 1997). This section has been referred to the early Palaeocene by Gayet et al. (1992), Bonaparte et al. (1993), and Muizon (1998). However, an early late Palaeocene age has been suggested by Marshall et al. (1997) and Pascual & Ortiz-Jaureguizar (2007). Recently, Gelfo et al. (2009) have reassessed the age of the Tiupampa mammal fauna and concluded that it is of early Palaeocene age. The Tiupampa mammal-bearing beds are regarded by these authors as a probable equivalent of the late Puercan (Pu3) of North America and would therefore be as old as 64 to 64.5 Ma. This hypothesis is based on the fact that the Tiupampa mammal-bearing beds are included in a single reversed stratigraphic series, which is likely to correspond to Chron 28r (see Gelfo et al. 2009 for discussion). However, when Gelfo et al. (2009) wrote their paper, the reference for calibration of Chron 28r was Lofgren et al. (2004), and the correlation was with the late Puercan (Pu3). New dates and calibration of the NALMAs have slightly modified the age and position of Chron 28r. According to Wilson (2013, 2014) and Sprain et al. (2014) Chron 28r is totally included in the base of the early Torrejonian (To1) and its absolute age is bracketed between c. 65 Ma and 64.866. This represents the very base of the early Torrejonian (To1), which spans from 65.118 Ma to c. 63.5 Ma. In other words, the absolute age for the Tiupampa fauna is c. 65 Ma. EMENDED DIAGNOSIS This following extensive diagnosis presents a list of the major morphological features of the skeleton and teeth of Alcidedorbignya inopinata and represents, in fact, a summarized description. Below a differential diagnosis is also provided. General morphology Small size by pantodonts standards; tail, long, 70% of the head and body length. Teeth Dental formula I3/3, C1/1, P4/4, M3/3; incisors spatulate; I1 distinctly smaller than I2-3; contralateral I1s widely separated from each other; i1 i3; C and c large, protruding, splayed labially; P1-2 and p1-2 single rooted and proodont (i.e. single elevated cusp); P3-4 and p3-4 semimolariform; P3-4 with strongly V-shaped paracone and protocone (double V-shaped); M1-3 with distinct pre- and postcingula; paraconule well developed; metaconule weak to indistinct; protocone anteroposteriorly broad; paracone and metacone separated at base (i.e. not connate); M1 with paracone and metacone subequal in size; M2 with paracone slightly higher than metacone; M3 with paracone distinctly higher and much more voluminous than metacone; M1-2 with moderately dilambdodont ectoloph (i.e. slightly V-shaped centrocrista); well-developed wing-like preparacrista (including parastyle) and postmetacrista (including metastyle); well-developed stylar shelf approximately 30% of tooth width on M2; no mesostyle; M3 with wing-like preparacrista (including parastyle) and virtually no postmetacrista; lower molars increase in size posteriorly with m1 distinctly smaller than m2; trigonids wider than talonids; protoconid and metaconid subequal in size, paraconid smaller; antero- and posterocingulid weakly developed; talonid basined; m3 talonid elongate. Skull Dome-shaped skull in lateral view, with the nasals sloping anteriorly; greatest width of the skull at the level of the posterior root of the zygomatic arch, slightly anterior to the level of the anterior edge of the dentary-squamosal articulation; rostrum approximately twice as wide at base (level of the anterior edge of the orbits) as at apex; in dorsal view nasals distinctly wider posteriorly; frontal-parietal suture on sagittal plane located at mid-length of the skull; numerous foramina for temporal rami on the parietal and at the parietal-squamosal suture; small sagittal crest; bilobate nuchal crest strongly protruding posteriorly; palate narrow (less than two M2 widths); long parallel-sided basipharyngeal canal (approximately 20% of the total length of the skull); large triangular ectopterygoid process of the alisphenoid; small posterior opening of the alisphenoid canal opening just anterior to the foramen ovale; anterior end of the canal opening internally just posterior to the foramen rotundum; foramen rotundum and sphenorbital fissure separated but adjacent one to the other and opening anteriorly in the same common fossa; large ascending process of the palatine in the orbit; large descending process of the frontal posterior to the palatine process; maxilla does not contribute to the lateral wall of the skull; two large diploic frontal foramina above the orbit; double lacrimal foramen; large wing of the lacrimal on face; jugal-maxilla suture bifurcated; jugal-lacrimal contact; zygomatic arch relatively slender; postglenoid process narrow and elevated (more elevated than wide), approximately half the transverse width of the glenoid cavity; postglenoid foramen on the medial edge of postglenoid process; presence of a tubercle (postglenoid eminence) on the posteromedial edge of the foramen; relatively flat promontorium with a distinct sigmoid groove for the internal carotid artery; promontorium totally separated from the alisphenoid, basioccipital and basisphenoid; deep notch for the internal carotid artery in the posterolateral angle of the basisphenoid; apex of the promontorium truncated; epitympanic recess opened ventrally and formed by the squamosal laterally and the petrosal medially; large foramen for the ramus superior of the stapedial artery opening in the petrosal; triangular post-promontorial tympanic sinus posterior to the external aperture of the cochlear fossula; spur-like medial caudal tympanic process on posterior angle of postpromontorial tympanic sinus; conical subarcuate fossa; vestigial anterior lamina of the petrosal; presence of an intracranial cavity (the petrosquamosal fossa) for the passage of the ramus superior of the stapedial artery and its tributary vessels and, capsuloparietal emissary vein and tributaries; long and deep groove on cerebral face of the braincase for the orbitotemporal artery and vein; large mastoid exposure on occiput; large post-temporal foramen in the squamosal petrosal suture; ectotympanic horseshoe-shaped, with distinct styliform process ventrally; anterior crus of the ectotympanic with a double articulation with squamosal laterally and petrosal medially. Dentary Stout body with a roughly constant height; symphysis fused in adults; ramus triangular with a large masseteric fossa, coronoid process recurved posteriorly and almost as wide at apex as at base; strong and salient coronoid crest at anterior border of masseteric fossa; condyloid process well above occlusal plane; angular process extends posterior to the level of the condyle; angular process hook-like but robust and almost as long as high; anteroposteriorly oriented crest on medial face of the angular process for the insertion of the pterygoideus medialis. Postcranial skeleton Axis with anteroposteriorly elongated neural process; 13 thoracic vertebrae, 9 lumbar vertebrae, 4 sacral vertebrae, and approximately 18 caudal vertebrae; long neural processes of the thoracic vertebrae; scapula with a large triangular supraspinatus fossa and a narrow and deep infraspinatus fossa; spine elevated; acromion anteriorly and distally projected; humerus with greater tubercle slightly higher than the head; deltopectoral crest limited to proximal half of the bone; very robust, long, and medially projecting medial epicondyle; well-developed epicondylar ridge; medial crest of the humeral trochlea projecting more distally than the lateral; ulna bent anteriorly and medially; deep fossa for the flexor muscles on medial face of olecranon and diaphysis; trochlear notch wide open; angle between humeral and radial facets (in anterodistal view) obtuse; radius with ovalshaped proximal epiphysis; centrale present; five anterior digits with short metacarpals; no size reduction of any digit; ungual phalanges with robust palmar tubercle; innominate with a distinctly everted ilium and a ventrolaterally deflected anteroventral spine; acetabulum relatively shallow and open; femur with a spherical head; greater trochanter as high as the head; lesser trochanter triangular, blade-like, and posteromedially oriented; small third trochanter; distal epiphysis as wide as deep; tibia with a salient tibial crest and tubercle; fibula with a well-developed interosseous crest on its proximal half; tibial trochlea on the astragalus relatively flat and angle between the medial and lateral tibial facets more than 120°; angle between lateral tibial facet and fibular facet close to 90°; astragalus with a distinct cuboid facet on the head; calcaneofibular facet present on the calcaneus lateral to ectal facet; well-developed peroneal process of the calcaneus; calcaneus with a strongly oblique (in dorsal view) cuboid facet, which faces distolaterally; presence of a supplementary articular facet for the astragalus on the medial edge of the cuboid facet; five pedal digits slightly longer than the manual ones, ungual phalanges cleft, with distal half expanded transversely (scutiform) in dorsal view and deflected palamarly or plantarly in lateral view, with robust plantar tubercle. DIFFERENTIAL DIAGNOSIS Alcidedorbignya inopinata is similar in size to Harpyodus euros and H. decorus but it is much smaller than all the other Pantodonta. Alcidedorbignya inopinata differs from all the other Pantodonta in having single rooted P2 and p2, and a hook-like angular process of the dentary. Alcidedorbignya inopinata differs from all the other Pantodonta except Bemalambda in having a distinct (although short) neck of the astragalus. It further differs from Pantolambda bathmodon in the following characters: size approximately 60% (not 40% as stated by Muizon & Marshall 1992) smaller, lack of a mesostyle on the upper molars, broader stylar shelf, posteriorly protruding bilobate nuchal crest, a horse-shoe shaped ectotympanic (not expanded medially as in Pantolambda), more gracile limb bones, ulna distinctly bent anteriorly and medially, obtuse angle between the anterior edge of the radial and trochlear notches of the ulna (acute angle in Pantolambda), much less developed and less everted anteroventral iliac spine, medial condyle of the femur similar in size to the lateral one (i.e. not projecting posteriorly), presence of a well-developed interosseous crest on the medial edge of the fibula, presence of a distinct (although short) neck of the astragalus, cleft pedal ungual phalanges (In pantolambda the anterior pedal phalanges are cleft; the posterior are not), distal half of ungual phalanges deflected palmarly or plantarly. Alcidedorbignya inopinata further differs from Harpyodus decorus and H. euros in the well-separated paracone and metacone, the V-shaped centrocrista and the much thinner postcingulum, whereas in Harpyodus the cusps are connate at base, the postcingumlum is much thicker and the centrocrista is straight. Alcidedorbignya inopinata further differs from Bemalambda in the following characters: size approximately 75% smaller, well-separated paracone and metacone at base (not connate), lack of the anteroposterior compression of the upper molars, lack of the great enlargement of the metaconid observed in Bemalambda, much lower sagittal crest, bilobate nuchal crest, lack of a well-developed postorbital process, much lower sagittal crest, dorsoventrally lower dentary in its anterior half, condyloid process located well above the level of the occlusal plane of the molars, much longer neural process of the axis, presence of 13 thoracic, nine lumbar, and four sacral vertebrae (respectively 17T, 8L, and 3S in Bemalambda), more gracile limb bones, ulna distinctly bent anteriorly and medially, presence of a much less developed and everted anteroventral iliac spine, medial condyle of the femur similar in size to the lateral (i.e. not projecting posteriorly as in Bemalambda), and presence of a well-developed interosseous crest on the medial edge of the fibula. NB: some of the above-mentioned morphological differences between Alcidedorbignya and larger pantodonts may be related to allometric phenomenons, which yet remain to be investigated (e.g., robustness of limb bones)., Published as part of Muizon, Christian de, Billet, Guillaume, Argot, Christine, Ladevèze, Sandrine & Goussard, Florent, 2015, Alcidedorbignya inopinata, a basal pantodont (Placentalia, Mammalia) from the early Palaeocene of Bolivia: anatomy, phylogeny and palaeobiology, pp. 397-634 in Geodiversitas 37 (4) on pages 410-412, DOI: 10.5252/g2015n4a1, http://zenodo.org/record/5210632, {"references":["MUIZON C. DE & MARSHALL L. G. 1987 c - Le plus ancien Pantodonte (Mammalia) du Cretace superieur de Bolivie. Comptes Rendus hebdomadaires des Seances de l'Academie des Sciences, Paris 304: 205 - 208.","MUIZON C. DE & MARSHALL L. G. 1992. - Alcidedorbignya inopinata (Mammalia: Pantodonta) from the early Paleocene of Bolivia: phylogenetic and paleobiogeographic implications. Journal of Paleontology 66 (3): 499 - 520.","MARSHALL L. G., SEMPERE T. & BUTLER R. F. 1997. - Chronostratigraphy of the mammal-bearing Palaeocene of South America. Journal of South American Earth Sciences 10: 49 - 70.","LOFGREN D. L., LILLEGRAVEN J. A., CLEMENS W. A., GINGERICH P. D. & WILLIAMSON T. E. 2004. - Paleocene Biochronology: The Puercan through Clarkforkian Land Mammal Ages, in WOODBURNE M. O. (ed.), Late Cretaceous and Cenozoic Mammals of North America. Biostratigraphy and Geochronology. Columbia University Press, New York: 43 - 105.","WILSON G. P. 2013. - Mammals across the K / Pg boundary in Northeastern Montana, USA: Dental morphology and bodysize patterns reveal extinction selectivity and immigrant-fueled ecospace filling. Paleobiology 39: 429 - 469.","SPRAIN C. J., RENNE P. R., WILSON G. P. & CLEMENS W. A. 2014. - High-resolution chronostratigraphy of the terrestrial Cretaceous-Paleogene transition and recovery interval in the Hell Creek region, Montana. Geological Society of America Bulletin Published online on 16 September 2014. http: // dx. doi. org / 10.1130 / B 31076.1"]}

International audience; New isolated petrosals from the Itaboraí beds of Brazil (late Palaeocene or early Eocene) are here described and referred to the early diverging litoptern Miguelsoria parayirunhor, based on phylogenetic, size, and abundance arguments. Both the external and internal anatomy of these specimens were investigated, which for the first time document many details of the auditory region of a Palaeogene litoptern. Our cladistic analysis, which included our new observations, failed to recover a monophyletic Litopterna but did not exclude it. A constrained analysis for the monophyly of this order showed that several features such as a (sub)quadrangular and anteroposteriorly elongated tensor tympani fossa and a large notch in the vicinity of the external opening of the cochlear canaliculus may constitute synapomorphies for Litopterna. The evolution of several other auditory characters amongst Litopterna is discussed and the relative dimensions of the inner ear and surrounding petrosal in the group were also investigated. This allowed detection of negative allometry of the bony labyrinth within the petrosal, which was confirmed by measurements and regression analysis across a larger sample of placental mammals. This scaling effect probably has an important influence on several characters of the bony labyrinth and petrosal, amongst which are the length of the vestibular aqueduct and cochlear canaliculus. It demonstrates that many aspects of the morphological variation of the bony labyrinth need to be thoroughly investigated before being incorporated into phylogenetic analyses.

International audience

International audience