ARTICLE

THE ‘CONDYLARTH’ RAULVACCIA PELIGRENSIS (MAMMALIA: DIDOLODONTIDAE)FROM THE PALEOCENE OF PATAGONIA, ARGENTINA

JAVIER N. GELFO1

1CONICET Depto. Científico Paleontología de Vertebrados, Museo de La Plata. Paseo del Bosque s/n (B1900FWA)La Plata. Buenos Aires, Argentina. jgelfo@fcnym.unlp.edu.ar

ABSTRACT—The Paleocene locality of Punta Peligro (Hansen Member of the Salamanca Formation) in Argentina hasyielded not only ‘condylarths’ but also an extraordinary assemblage of therian mammals derived from Laurasian immi-grants and non-therian mammals, relicts of the Mesozoic Gondwanan radiation. The materials, a left jaw fragment withthe talonid of the second molar and the third molar, and an isolated upper molar, allow the revalidation of Raulvacciapeligrensis considered previously as a junior synonym of Escribania chubutensis. In addition to other characters, Raul-vaccia strongly differs from E. chubutensis in its lesser size, the development of the m3 talonid, the presence of ahypocristid, and a postcristid. Originally Raulvaccia and Escribania were considered as Mioclaenidae, Kollpaniinae,together with other ungulates from the Santa Lucía Formation, from the early Paleocene locality of Tiupampa in Bolivia.In contrast to the Tiupampan ‘condylarths,’ Raulvaccia shares derived characters with E. chubutensis, particularly in theupper molars, such as a strong parastyle and the presence of hypocone located close to, but well differentiated from theprotocone. These characters support a previous hypothesis which argues for the removal of the Peligran ‘condylarths’from the more primitive Kollpaniinae, and sustains its relationship to the exclusively South American Didolodontidae.The revalidation of Raulvaccia peligrensis shows that the diversity of placental mammals during the earliest knownPaleocene in Patagonia was greater than previously thought, and supports for the early differentiation of the Didolo-dontidae.

INTRODUCTION

The earliest known Paleocene mammalian localities of SouthAmerica are restricted to Punta Peligro (Argentina) (Fig. 1),Tiupampa (Bolivia), and Laguna Umayo (Perú) (Bonaparte etal., 1993; Marshall and Muizon, 1988; Sigé et al., 2004). Thefossiliferous locality of Punta Peligro in Chubut Province, Ar-gentina, represents the oldest Cenozoic fossil mammalian assem-blage recorded in Patagonia. This fauna came from the basallevels of the ‘Banco Negro Inferior’ (BNI), the Hansen Memberof the Salamanca Formation (Andreis et al., 1975). In addition tothe fossil record of Leptodactylidae, Chelidae and Alligatoridae(Bonaparte et al., 1993) there is a mixture of non-tribosphenicGondwanan mammals and mammals derived from the Laurasianboreosphenid stock. Based on the mammalian fauna, Bonaparteand colleagues (1993) proposed the recognition of a new SouthAmerican Land Mammal Age (SALMA), the Peligran (earlyPaleocene), originally considered as younger than the Tiupam-pan SALMA of Ortiz-Jaureguizar and Pascual (1989), definedon the basis of the fossil record of Santa Lucía Formation, at theBolivian locality of Tiupampa (Muizon, 1992), and older than theItaboraian SALMA. In contrast Marshall and colleagues (1997)proposed that the Peligran SALMA was older than the Tiupam-pan, so no agreement has been reached yet about the relative ageof these SALMAs. In this paper, the Peligran is considered asyounger than the Tiupampan following Bonaparte and col-leagues (1993), Bonaparte and Morales (1997), and Muizon andCifelli (2000).

The Peligran fauna includes some Mesozoic Gondwanan lin-eage mammals (Pascual and Gelfo, 2004) represented by thedryolestid Peligrotherium tropicalis Bonaparte, Van Valen, andKramarz, 1993, (Gelfo and Pascual, 2001), the monotremeMonotrematum sudamericanum Pascual, Archer, Ortiz Jauregui-

zar, Prado, Godthelp, and Hand, 1992; and the GondwanatheriaSudamerica ameghinoi Scillato-Yané and Pascual, 1984(Bonaparte et al., 1993; but see also Pascual et al.,1999). How-ever, the Peligran fauna offers no records of the more primitiveEutheria or Metatheria, which in contrast are present atTiupampa, and whose radiation dominated the Cenozoic mam-malian history of South America. The metatherians are repre-sented at least by a ‘?Didelphoidea, aff. Derorhynchus’ (Bond etal., 1995), and Polydolopimorphia, Bonaparthreriidae (Goin etal., 2004). The eutherian record includes the taxa Requisia vid-mari Bonaparte and Morales, 1997, a Litopterna; Notonychopi-dae (but see Soria, 1988a for consideration of the Notonychopi-dae as Notopterna) and Escribania chubutensis Bonaparte,Van Valen and Kramarz, 1993, a didolodontid ‘condylarth’(Gelfo, 1999, 2004). The placentals found in Punta Peligro rep-resent native South American groups, more derived than theearliest known Laurasian mioclaenid immigrants recorded inTiupampa.

In this context and based on a fragmentary left dentary with apoorly preserved tooth interpreted as an m2, Raulvaccia peli-grensis from the early Paleocene of Punta Peligro was originallydescribed as a Peligran mioclaenid ‘condylarth’ (Bonaparte etal., 1993). Together with Escribania chubutensis, and theTiupampan Mioclaenidae, these taxa were placed in the subfam-ily Kollpaniinae (�Molinodinae sensu Bonaparte et al. 1993).But the discovery of new remains corresponding to the uppercheck teeth of Escribania chubutensis led to the recognition ofderived features that justified its separation from the Mioclaeni-dae and association with the more advanced Didolodontidae(Gelfo, 1999, 2004). Finally, Raulvaccia was considered as a jun-ior synonym of Escribania, interpreting the only badly preservedtooth as a m1 of the latter (Muizon and Cifelli, 2000).

In this article, new materials that allow the reconsideration of

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the systematic status of Raulvaccia peligrensis are described, andanalysed in the context of the Peligran SALMA.

Institutional Abbreviations—AMNH, American Museum ofNatural History, New York, USA; MACN, Museo Argentino deCiencias Naturales ‘Bernardino Rivadavia,’ Buenos Aires, Ar-gentina; MCT, Museu de Ciências da Terra, Rio de Janeiro,Brazil; MHNC, Museo de Historia Natural de Cochabamba, Bo-livia; MN, Museu Nacional, Rio de Janeiro, Rio de Janeiro, Bra-zil; MLP, Museo de La Plata, Buenos Aires, Argentina; MPEF-PV, Museo Paleontológico Egidio Feruglio, Trelew, Argentina;PVL, División Paleontología de Vertebrados, Fundación MiguelLillo, Tucumán, Argentina; UNPSJB-PV, Universidad NacionalPatagónica San Juan Bosco, Comodoro Rivadavia, Argentina.YPFB Pal, Yacimientos Petrolíferos Fiscales Bolivianos, Colec-ción Paleontología, Santa Cruz, Bolivia.

SYSTEMATIC PALEONTOLOGY

MAMMALIA Linnaeus, 1758PLACENTALIA Owen, 1837

PANAMERIUNGULATA Muizon and Cifelli, 2000DIDOLODONTIDAE Scott, 1913

RAULVACCIA Bonaparte, Van Valen, and Kramarz, 1993RAULVACCIA PELIGRENSIS Bonaparte, Van Valen, and

Kramarz, 1993

Holotype—UNPSJB PV 915, left dentary with part of the m1with the distal side of the talonid and the protoconid, broken.

Hypodigm—The holotype, and MLP 90-II-12-69, left dentarywith the talonid of the m2 and the complete m3. MLP 90-II-12-70, left M1? with almost complete labial roots.

Revised Diagnosis—Medium-sized Didolodontidae, smallerthan Escribania but larger than Asmithwoodwardia. The lower

crown height, and bunodont molars differ from KollpaniinaeMioclaenidae in the following characters: trigonid as wide as thetalonid; entoconid and hypoconulid well individualized, not con-nate, fused or forming an obliquely oriented distolingual crest;and presence of hypocone. Together with Escribania chubuten-sis, Raulvaccia peligrensis differs from the rest of the Didolodon-tidae in having a rounded precingulum and postcingulum; thelarge parastyle mesial to the paracone; and the hypocone con-nate with the protocone. Raulvaccia differs from Escribania andall the rest of the didolodontids in the following combination offeatures: (1) m3 precingulid continuing around the labial side ofthe tooth only interrupted at the hypoconid, (2) strong hypocris-tid and postcristid, (3) entocristid present and cuspidate, and (4)wider talonid basin.

Description—The only part of the m2 that is preserved is thedistal side of the talonid where the hypoconid is the higher cusp(Fig. 2). The lower cusp seems to be the hypoconulid, projectingdistally and slightly closer to the entoconid than to the hypo-conid. The entoconid is only slightly more distally located withrespect to the hypoconid. The hypoconulid is connected to thehypoconid by the hypocristid, and with the entoconid by thepostcristid. The postcingulid extends from the labial base of thehypoconulid to the distolabial edge of the talonid, seeminglyoverlapping the precingulid of the m3.

The m3 is proportionally smaller than that of Escribaniachubutensis (Table 1 and Fig. 3). The strong precingulid does notexpand farther on the lingual edge, but it continues around thelabial side of the trigonid. The labial cingulid is briefly inter-rupted at the hypoconid and extends up to the mesial face of thehypoconulid.

The trigonid cusps are bunoid and subequal in size, with theprotoconid slightly larger than the other cusps. The bulbous baseof the cusps fills the trigonid basin. This is more evident at thecontact between the protoconid and the paraconid that divides,in occlusal view, the trigonid basin into a mesiolabial portion anda distolingual one. The first is situated behind the paracristid andpractically adjacent to the mesiolingual edge of the protoconid,whereas the second is behind the paraconid, between the proto-conid and metaconid, and mesial to the protocristid. In occlusalview, the paraconid is more labial than the metaconid, and evenwhen connate with this cusp, it is clearly distinguished from it.The low paracristid extends mesially from the protoconid beforecurving toward the lingual side to a point located behind thehypoconulid of the m2, and from there, it arches distally to reachthe paraconid. The protocristid is straight, low and wide, whereasthe metacristid is absent. The metaconid is clearly distal to theprotoconid, but not strongly inflated as in the Kollpaniinae inwhich it invades the talonid basin distally.

The talonid of the m3 is expanded distally, and narrower thanthe trigonid. The hypoconid is the largest cusp of the talonid. Theshort and robust cristid obliqua projects mesially to the lingualedge of the protocone. The talonid basin is wide and deep, andopen lingually behind the metaconid. The hypoconulid, distallyplaced in the talonid, is a high and massive cusp, connected to theentoconid and hypoconid, by the postcristid and hypocristid re-spectively, which are stronger than in the m2. Distally to thehypoconid, there is a rounded and low cusp that interrupts thecontinuity of the hypocristid. The entoconid is more distally lo-cated than the hypoconid, even more than in the m2. A shortentocristid projects mesially but doesn’t contact the distal wall ofthe metaconid, so the talonid basin is open lingually. A smallercusp is present on the entocristid, mesial to the entoconid. Thiscusp is clearly different from the isolated cusp that is presentmesial to the entoconid in the m2 of the Escribania chubutensisholotype (UNPSJB-PV 916) that obliterates the talonid basin,and is not associated with an entocristid. The cristid obliqua iswide, short and arching toward the distolingual side of the meta-cone, ending in a very small cusp attached to the distal wall of the

FIGURE 1. Location map of Punta Peligro locality, Chubut province,Argentina.

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trigonid. This cusp is not in the same position than the charac-teristic mesoconid of Didolodus multicuspis Ameghino, 1897.

The M1? cusps are bulbous, with the protocone, paraconealmost equal in size, and the metacone somewhat smaller (Fig.2). As in many other ‘condylarths,’ the paracone is slightly labial

in position with respect to the metacone. The centrocrista is lowand rounded. The preparacrista is not well defined because ofwear and the proximity of the parastyle and the paracone. Theparastyle is well developed and very worn, oval in outline, withthe major axis perpendicular to the centrocrista, and located on

TABLE 1. Measurements and descriptive statistics of m3s of the Kollpaniinae and Didolodontidae.

Taxa

m3 length Talonid length Talonid width Talonidarean mean SD mean SD mean SD

Andinodus boliviensis 1 6.6 0 3.55 0 3.36 0 11.92Molinodus suarezi 5 4.26 0.32 2.52 0.13 2.35 0.32 5.93Simoclaenus sylvaticus 1 5.27 0 2.95 0 3.31 0 9.76Pucanodus gagnieri 1 2.97 0 1.53 0 2 0 3.06Tiuclaenus cotasi 3 3.15 0.43 1.75 0.69 1.33 0.05 2.33Tiuclaenus robustus 1 3.06 0 1.15 0 1.42 0 1.63Tiuclaenus minutus 3 2.58 0.05 1.42 0.07 1.38 0.07 1.96Escribania chubutensis 2 11.4 0.63 6.77 0.17 5.7 0.42 38.61Raulvaccia peligrensis 1 7.8 0 4.7 0 4.2 0 19.74

Materials measured belong to: Andinodus boliviensis MHNC 1241; Molinodus suarezi YPFB Pal 6112, YPFB Pal 6113, YPFB Pal 6114, MHNC 1238,MHNC 8269; Simoclaenus sylvaticus MHNC 8332; Pucanodus gagnieri Muizon and Marshall, 1991, MHNC 1239; Tiuclaenus cotasi Muizon andCifelli, 2000, MHNC 1231, MHNC 1232, MHNC 1254; Tiuclaenus robustus Muizon and Cifelli, 2000, MHNC 1233; Tiuclaenus minutus Muizon andMarshall, 1987a, YPFB Pal 6115, MHNC 8335, MHNC 1252; Escribania chubutensis UNPSJB PV 916, MLP 93-XII-10-1; Raulvaccia peligrensis MLP90-II-12-69.All measurements in millimeters.Abbreviations: n, number of materials; SD, standard deviation.

FIGURE 2. Raulvaccia peligrensis. A and B MLP 90-II-12-69, left dentary with the talonid of m2 and the m3; C and D MLP 90-II-12-70, left M1?

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the mesiolabial side of the precingulum. The postmetacrista islow and short, and connects the metacone with a weak metastyle.The paraconule and metaconule are subequal in size and smallerthan the paracone and metacone. Between the paraconule andthe paracone there is a very small basin surrounded by the pre-paraconular and the postparaconular cristae. This basin is notobserved between the metaconule and metacone, where thebases of these cusps are in contact. The paraconule is connectedlingually with the protocone by a low and rounded preproto-crista, whereas the metaconule is linked to the distal side of thehypocone by a short crista. The preparaconular crista extendsmesiolingually from the paraconule and bends to contact theparacrista independently from the precingulum. A short post-paraconular crista contacts the lingual wall of the paracone. Thepremetaconular crista, larger than the latter, reaches the mesio-lingual base of the metacone. The postmetaconular crista is alarger structure that seems to reach the postcingulum near thelingual side of the metacrista. In spite of the development of thepostparaconular and premetaconular cristae and because of theirorientations, they do not fill the trigon basin. The protoconeseems to have been a large cusp, as high as the paracone or themetacone, but is now erased by wear. The hypocone, locateddistolingually and connate with the protocone, is lower, elliptical,and with its major axis positioned anterodistally.

The precingulum is strongly arched, and extends mesiolabiallyfrom the base of the protocone to the parastyle. A small proto-style is present near the base of the protocone. No cingulum ispresent in the lingual side of the tooth. Even though the toothenamel tooth is broken labially to the metacone, the labial cin-gulum seems to be present, as a prolongation of the rim thatprojects mesiolabially from the metastyle. The labial cingulum isinterrupted at the paracone. In lingual view the postcingulum ishigher than the precingulum and extends distolabially from thehypocone, parallel to the postmetaconular crista, curving slightlyto reach the metastyle.

Comparison with Escribania chubutensis—The nominationof Raulvaccia peligrensis was based on a single specimen

(UNSPSJB PV 915), a fragment of left jaw with a broken toothinterpreted originally as an m2 (Bonaparte et al. 1993). Escriba-nia chubutensis from the same horizon and locality was describedbased on a left jaw with the m2–3 (Bonaparte et al., 1993). Al-though they presented some differences relative to Molinodussuarezi Muizon and Marshall, 1987a, such as the more labiallocation of the paraconid, the reduction of the trigonid basin, thedistal expansion of the talonid in the m3 (Fig. 4G) and a sizethree times larger (Fig. 3), both taxa were assigned to the Mio-claenidae, Kollpaniinae (Bonaparte et al., 1993). Recently,Muizon and Cifelli (2000) argued that Raulvaccia was a juniorsynonym of Escribania chubutensis and contrary to the originaldescription considered the only known tooth as an m1. Thisassertion was based on the observation that the root alveolusthat lies mesial to the tooth in the Raulvaccia holotype is toonarrow, and better suited to a p4, and because the differencesbetween Raulvaccia and Escribania were similar to those presentbetween the m1 and m2 of the Didolodontidae Paulacoutoiaprotocenica (Paula Couto, 1952) or the mioclaenid Molinodussuarezi. But the width of the jaw at the level of the m1 alveolusin the holotype of Escribania chubutensis, is greater than thatobserved at the same position below the tooth of the type ofRaulvaccia, (10.95 and 6.95 mm, respectively). Even though theventral portion of the Raulvaccia jaw is broken, its entire sizeseems to be much smaller than that of Escribania. Consideringthe whole mammalian assemblage of the BNI at Punta Peligro,Escribania chubutensis has the most robust jaw, even larger thanthe largest known dryolestid Peligrotherium tropicalis (Gelfo andPascual, 2001) also recorded in the Peligran SALMA. For now,the only possible comparison for Raulvaccia holotype tooth iswith a new specimen of Escribania chubutensis, (MPEF-PV1860), a right jaw with an undoubted m1. The m1 of Escribaniahas a minimum length of 7.4 mm—the mesiolabial side of the

FIGURE 4. Illustrations of left last lower molars based on A, Molino-dus suarezi (holotype YPFB Pal 6112); B, Tiuclaenus minutus (MHNC1252); C, Pucanodus gagnieri (holotype MHNC 1289, reversed); D, Si-moclaenus sylvaticus (holotype MHNC 8332, reversed); E, Paulacoutoiaprotocenica (MN 1431); F, Didolodus multicuspis (MLP 61-VIII-3-207reversed); G, Escribania chubutensis (MLP 93-XII-10-1). Upper scalebar equals 4 mm, lower scale bar equals 10 mm.

FIGURE 3. Talonid area of m3 (mm2) versus total length of m3 (mm),for the Kollpaniinae and Didolodontidae. Values from table 1.

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trigonid is broken—and a width of 5.92 mm, whereas Raulvacciais 6.4 mm long and 4.65 mm wide. Even if a larger sample isneeded to evaluate these dimensions, and even if the Raulvacciatype (UNSPJB PV 915) could be in fact an m1 as Muizon andCifelli (2000) state, the jaw and tooth size do not seem to belongto Escribania chubutensis but to a smaller, and more slendertaxon. The remains presented here, MLP 90-II-12-69 and MLP90-II-12-70 exhibit a molar morphology comparable to that ofEscribania chubutensis but with some well-defined differentcharacters, and smaller size, which are like those present in theRaulvaccia holotype. For these reasons, and according to thediscussion below, the re-validation of the name Raulvaccia peli-grensis is proposed in this paper.

Raulvaccia differs from Escribania by the following charactersof the m2: the hypoconulid is located more distally in the talonid;the entoconid is higher and not as lingual to the hypoconulid.Even when smaller, the entoconid is placed almost as mesially asthe hypoconid. The location of these cusps indicates that thetalonid basin should be proportionally better developed in Raul-vaccia than in Escribania. Even though the postcingulid couldnot be clearly seen because of the contact between m2 and m3,it seems to be weaker than in Escribania.

In contrast to Escribania (Fig. 4G), the m3 of Raulvaccia hasa wide and well developed precingulid, which continues as asmall labial rim that extends from the labial side of the trigonidthrough the base of the protoconid. The mesial side of theprecingulid is obliterated by the distal face of the m2 hypoconu-lid which practically contacts the paracristid of the m3 at thesame level and seems to overlap the cingulid. Even though thebulbous bases of the cusps fill the trigonid basin, dividing thebasin into mesial and distal parts, the basin is proportionallygreater than in Escribania chubutensis. The Raulvaccia protoco-nid and the metaconid are more separated, so the protocristidconnecting both cusps is low and long. The paracristid is alsodeeply arched distally, but longer than in Escribania. Even whenthe paraconid portion of the paracristid describes a continuousweak arch, the protoconid portion is divided into two straightsegments. The first extends mesially from the protoconid, anddescribes a sharp curve labially to reach the paraconid portionof the paracristid, at a point located distal to the hypoconulid ofthe m2.

The talonid area in the m3 in Escribania chubutensis (Fig. 4G)is proportionally larger mesiodistally in Escribania than in Raul-vaccia. The proportion between the total area of the talonid andthe length of the m3 not only discriminates Escribania fromRaulvaccia (Fig. 3), but it also shows that the talonid area ofRaulvaccia is closer in size to the largest Kollpaniinae rather thanto Escribania. The hypoconulid, located in a more central posi-tion, is smaller and slender. In Escribania this cusp is very nearto the hypoconid and separated from it by a deep furrow thatcontinues through the groove which shapes the reduced talonidbasin. The talonid basin is divided into two portions, one locatedmesial and labial to the abovementioned groove and bearing astrong hypoconid; the other is distolingual and dominated by thepresence of the hypoconulid. In contrast, the hypoconulid ofRaulvaccia is distally distant from the hypoconid, associated by astrong hypocristid and even though the distance between thesecusps is larger than Escribania, no deep groove is present so thetalonid is not clearly divided into two parts. The entoconid,hardly defined from the large entocristid and practically twinedto the hypoconulid in Escribania, is well defined in this taxon,located far from the hypoconulid but connected to it by a sharppostcristid. The entocristid is very short and ends in a little cuspmesial to the entoconid. In addition to the aforementioned dif-ferences, the talonid basin of Raulvaccia is proportionally largerbecause the hypoconid and entoconid are not in contact as inEscribania chubutensis, in which the basin surface is narrower,even given the larger size of the talonid.

In the holotype of Escribania chubutensis the hypocristidprojects from the labial surface of the hypoconulid to the hypo-conid, but joins a very weak and interrupted labial cingulid(Bonaparte et al., 1993). This is not so clear in MLP 93-XII-10-1where these structures are hardly visible. In contrast, in Raul-vaccia a brief labial cingulid extends distally almost up to themesial face of the hypoconulid. The labial cingulid is divided bya vertical furrow into a faint mesial rim and a distal larger cin-gulid. The larger cristid that connects the hypoconulid and hy-poconid, seems to bear at least one small cusp. The hypoconid,which seems to be a slightly larger than the protoconid in Es-cribania, is equal in size to the protoconid in Raulvaccia. And incontrast to the strong and short cristid obliqua, in Raulvaccia amore slender cristid projects first in the direction of the lingualedge of the protoconid, and then curves to contact the labial sideof the metaconid. Both segments of the cristid obliqua, the distalone and the thinner mesial one, form an obtuse angle.

Only a few differences between these two taxa can be ob-served in the upper dentition (Fig. 5G). Despite its lesser size,the M1? of Raulvaccia is very similar in morphology, structureand distribution of its cusps. The presence of well developedpostparaconular and premetaconular cristae, which are absent inEscribania, are its more distinctive characters. A metastyle ispresent as a small cusp atop the postcingulum but the Escribaniaspecimens (MLP 90-II-12-63 right maxilla with M2–3 and MLP90-II-12-68 left maxilla with M2) are too worn to allow accuratecomparison (Gelfo, 1999).

In spite of the similarities between these molars, they show aninteresting difference in their wear pattern. The paracone andmetacone of Escribania, like the rest of its cusps, have a flat wearsurface, but in Raulvaccia such a wear surface is only observed inthe protocone and the hypocone, which are the most abradedcusps. In contrast, the higher paracone and metacone are onlyworn in the lingual side.

Comparison With Kollpaniinae—In contrast to the Kollpa-niinae (Fig. 4A–D) in which the entoconid and hypoconulid areconnate to fused, forming an obliquely oriented distolingual

FIGURE 5. Illustrations of right upper molars based on A, M1 ofMolinodus suarezi (MHNC 1247); B, M2 of Tiuclaenus minutus (MHNC1240); C, M2 of Pucanodus gagnieri (MHNC 8340); D, M2 of Simoclae-nus sylvaticus (MHNC 8348); E, Paulacoutoia protocenica (MCT 968reversed); F, M2 of Didolodus multicuspis (MLP 59-II-24-226 reversed);G, M2 of Escribania chubutensis (MLP 59-II-24-226). Upper scale barequals 2 mm, lower scale bar equals 10 mm.

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crest (Muizon and Cifelli, 2000), in Raulvaccia peligrensis thesecusps are well defined, subequal in size and more separated, as inDidolodontidae or in Protolipternidae. Despite the more similarratio of m3 talonid area versus the total length of Raulvaccia withrespect to Andinodus boliviensis Muizon and Marshall, 1987a, orto a lesser extent, to Simoclaenus sylvaticus Muizon and Cifelli,2000, (Fig. 3), the m3 of Raulvaccia differs from all the Kollpa-niinae in the following combination of characters: larger devel-opment of the trigonid basin, mesially and distally to the para-conid-protoconid contact; larger paraconid, even when connateat its base with the metaconid; larger paracristid; presence oflabial cingulum; talonid more expanded distally; stronger cristidobliqua; larger entoconid, located halfway between the hypo-conid and the hypoconulid; presence of a strong entocristid witha terminal mesial cusple; and the presence of postcristid andhypocristid.

In contrast to all the upper molars of the Kollpaniinae (Fig.5A–D), the M1? of Raulvaccia has a conspicuous hypocone justdistal to the protocone, which clearly changes the outline of thewhole molar, being more rounded in occlusal view. The majorand longer axis of the molars in the Tiupampan Kollpaniinae andeven in Pascualodus patagoniensis Gelfo 2004 from the Eoceneof Patagonia extends from the labial to the lingual side, but in theM1? of Raulvaccia the major axis projects from the mesial to thedistal side of the tooth. Other differences are the presence of ashort postparaconular crista, and a premetaconular crista. Butcaution is necessary regarding this character, because only a fewspecimens of Raulvaccia are known and even though these cris-tae usually tend to be reduced or disappear in ‘condylarths,’ theymay exhibit great individual and intraspecific variations. For ex-ample, Muizon and Cifelli (2000) argued that these cristae arevariably mpresent in basal arctocyonids, and North Americanmioclaenids. They mentioned them as present for Protoungula-tum and absent for Oxyprimus, while Luo (1991) stated just theopposite.

The parastyle or parastylar lobe (� stylocone plus true para-style, sensu Muizon and Cifelli, 2000) present in Raulvacciaseems to be larger than in the mioclaenids. Among the Kollpa-niinae, the parastyle is small to medium sized, but it is peculiarlylarge in MHNC 8280, an M1–2 of Molinodus suarezi Muizon andMarshall, 1987b, (Muizon and Cifelli 2000) and comparable butsmaller than in Raulvaccia.

Comparison With Other Didolodontidae—Raulvaccia ismost similar to the bunodont tooth of the rest of the Didolodon-tidae, which represents a primitive structure, but more advancedthan the Kollpaniinae, for characters such as the enlargement ofthe talonid with respect to the trigonid or the presence of thehypocone. The talonid of the m2 of Raulvaccia resembles Pau-lacoutoia in the similar arrangement of cusps but with a smallerhypoconid. Lamegoia is also similar in having well-differentiatedentoconid and hypoconulid. Simpson (1948) described the talo-nid of Didolodus as formed by a large crescentic hypoconid, anopposite, smaller and more conical entoconid, and a still smallersubconical hypoconulid at the midline and very slightly distal tothe other two cusps. But the morphological variation within Di-dolodus seems to be higher, and the talonid in the m2 differsfrom Raulvaccia in the presence of an hypoconulid that might beas high as the entoconid or even larger (for example AMNH28475), and located very distal to the hypoconid.

The trigonid of the m3 in Raulvaccia resembles Paulacoutoia(Fig. 4E) and Lamegoia in the size and location of cusps. Theconspicuous paraconid is larger and more clearly separated fromthe metaconid than in Paulacoutoia but less than in Lamegoia, inwhich this cusp seems to be even higher than the metaconid. Incontrast, in Didolodus the paraconid is connate or fused with themetaconid, and virtually invisible except with little wear.

Despite the general similarity, the lower tooth of Raulvacciadiffers from Paulacoutoia in the talonid of the m3, which is

longer, so the hypoconulid is located distally more distant fromthe hypoconid and connected to it by a cristid; the entoconid ismore distal than the hypoconid; the talonid basin is wider; andsupernumerary cusps and labial cingulum are present. In Pau-lacoutoia the precingulid ends in the mesiolingual portion of theprotoconid, whereas in Raulvaccia it encloses the base of thiscusp.

In the lower molars of Didolodus (Fig. 4F), in contrast toRaulvaccia, the trigonid is small and the paraconid is absent. Inthe talonid of the m2 the entoconid is as distally located as thehypoconulid, being practically lingual to it, the cristid obliquaextends mesially to the distolabial base of the metaconid andbears a minor cusp, and neither the labial cingulum nor thehypocristid are present. The lower molars of Lamegoia differ inthe exclusive direction of the cristid obliqua, and this is the onlyknown didolodontid in which this cristid projects straight fromthe hypoconid to the distal side of the protoconid. The entoconidis closer to the hypoconulid, and the postcingulid is restricted tothe labial side. The paraconid is comparable with Raulvaccia inits height and the degree of differentiation from the metaconid.Even though no m3 assigned to Lamegoia shows accessory cuspsnear the entoconid, this cusp is duplicated or has a mesial cusp inthe talonid of the m2 of MN1463-V. But this is not a constantcharacter, because no accessory cusp is associated with the en-toconid in the m2 of MCT 1487.

The hypocone in Raulvaccia is located very close to the pro-tocone. In lingual view the enamel between the protocone andhypocone is continuous, not divided by a vertical groove. Theprotocone and hypocone seem to be connate, but is important torecall that their closeness is heightened because the wear in theocclusal surface reduces the height of these cusps. This can beseen in the M2 of Lamegoia conodonta Paula Couto, 1952, forexample in MN 1465-V , or in Paulacoutoia protocenica (MN1459-V) where in contrast, the hypocone is larger and even whenvery close to the protocone, it is separated from it by a definiteand deep furrow seen in occlusal and lingual view (Fig. 5E).Raulvaccia also resembles Lamegoia in the crista that connectsthe hypocone to the metaconule. In Didolodus multicuspis(MACN 10690) the hypocone and protocone are subequal in sizeand, in lingual view appear with their bases clearly separatedfrom each other by a deep furrow. These cusps are only con-nected by a short and low crest. The hypocone is also moredistant from the metaconule (Fig. 5F).

The presence of the protostyle just mesial or mesiolingual tothe paraconule in Raulvaccia is shared with most of the Didolo-dontidae. Raulvaccia is more similar to Lamegoia and Paulacou-toia than Didolodus in the number and arrangement of the cusps,the interruption of the labial cingulum at the base of the para-cone, the protostyle, and the development of the preparaconularcrista.

The presence of parastyle with absence of mesostyle seems tobe an exclusive characteristic of Raulvaccia, only comparable toEscribania chubutensis and the reduced parastyle of Paulacou-toia protocenica. The mesostyle is also absent in Lamegoia co-nodonta but the parastyle is not as large. In contrast to the de-gree of development of the parastyle in Raulvaccia, Soria(1988a) argued that this cusp appears in Didolodontidae laterthan or at the same time as the mesostyle, and is never largerthan the latter. Consequently, he argues that no didolodontidshould be characterized by a unique development of the paras-tyle. This statement was based on the recognition of two informallineages in the Didolodontidae, the ‘Didolodus group,’ compris-ing the genera Didolodus, Lamegoia, Paulogervasia, and Proec-tocion, and the ‘Ernestokokenia group,’ with Ernestokokenia,Asmithwoodwardia, and Megadolodus (McKenna 1956; Soria1982, 2001; Soria and Hoffstetter 1983). Within this scheme, thefirst group could be characterized by the development of theprotostyle and mesostyle, whereas the parastyle remains incipi-

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ent, and in contrast, the other group shows a more primitivepattern with the development of only six principal cusps, withoutstylar cusps (Soria 1988a). This seems to disallow the inclusion ofRaulvaccia and Escribania within Didolodontidae, given thepresence of a strong parastyle in these taxa. However, the phy-logenetic relationships of the Didolodontidae, show that theseproposed lineages were artificial (Cifelli 1983, 1993), as the gen-era of the so-called ‘Ernestokokenia group’ have been regardedas Litopterna (Cifelli 1983; Cifelli and Villarroel 1997), andErnestokokenia has been considered as a junior synonym ofAsmithwoodwardia (McKenna and Bell 1997; but see oppositeopinions about the status of Ernestokokenia in Muizon and Ci-felli 2000; Soria 2001). Thus the presence of parastyle in Raul-vaccia, Escribania, and Paulacoutoia seems to be congruent withthe most recent phylogenetic approach, which considers that theKollpaniinae Mioclaenidae represent the basal group of the Di-dolodontidae and Litopterna (Muizon and Cifelli 2000; Gelfo2004).

Comparison With Litopterna—Raulvaccia resembles alsotaxa with a brachyodont and bunodont to bunoselenodont den-tition. The systematic positions of these taxa are in question. Asthis conflict exceeds the scope of this work, the comparisons willrefer to specific specimens, with few references to their system-atic position.

Asmithwoodwardia and Miguelsoria, taxa considered as hav-ing a morphologically primitive dentition, were regarded as di-dolodontid ‘condylarths’ and then moved to the Litopterna inthe Protolipternidae together with Protolipterna (Cifelli 1983).In spite of this, these taxa were still regarded as Didolodontidaeby Soria (2001). This seems to be correct at least for Asmith-woodwardia, because no character justifies its inclusion in theLitopterna (Gelfo and Tejedor, 2004). The bulbous cusps ofthese taxa are comparable to what is seen in Raulvaccia, but them3 differs from it by its larger trigonid size and the presence ofa conspicuous paraconid, which in Protolipterna and Asmith-woodwardia is variably seen as connate with the base of themetaconid if the wear process is not so advanced. The talonid ofthe m3 of Raulvaccia differs by being mesiodistally longer, inhaving a strong hypocristid and postcristid, and in the presenceof a cuspule in the entocristid. The hypocone of Raulvaccia isstrongly connate to the protocone, and not divided by a lingualfurrow as in Asmithwoodwardia or Protolipterna. It also differsin the bigger size of the preparaconular and postmetaconularcristae, the large parastyle, and the internal concave, mesial andpostcingulum.

Raulvaccia peligrensis looks less like other problematic groupof litopterns with more bunoselenodont teeth. The Anisolamb-dinae have been considered as a subfamily of the Protheroteri-idae (Cifelli, 1983) or as the independent family Anisolambdidae(Soria, 2001). The uppers molars of this taxon are clearly differ-ent because of the P4-M3 with their crescentic paracones andmetacones, and the strong development of the parastyle andmesostyle. Even though the lower molars are bicrescentic ornearly so, with lophate trigonids and talonids, they seem to becomparable to Raulvaccia. For instance, Wainka tschotsheSimpson, 1935 shows some similar details in the m3 (AMNH29101), particularly in the distal extension of the talonid. But itdiffers from Raulvaccia in its larger size, proportionally largertrigonid, and a crescent-shaped protoconid that projects a strongparacristid which does not contact the paraconid. In addition theparaconid is as high as the metaconid and located far from it, notconnate to its base as in Raulvaccia but occupying a more labialand central position in the trigonid. The protocristid is high andconnects the metaconid with the protoconid. The mesiolingualside of the trigonid seems to be reduced. The talonid is lowerthan the trigonid, with the entoconid and the hypoconulid lo-cated practically in the same mesiodistal line. As in the trigonid,the labial side is crescent, a large hypoconid continues mesially as

the cristid obliqua to the more labial side of the metaconid base,and a distal crest descends to the labial base of the hypoconulid,which is very distally located, as in Raulvaccia.

The presence of a strong parastyle in Raulvaccia, as in Escriba-nia, is one of the more peculiar features of this taxon. This is alsoseen in the Litopterna Notonychopidae: Requisia vidmarni,which is also from the levels of BNI (Bonaparte and Morales,1997), and Notonychops powelli Soria, 1988, from the Río LoroFormation in Tucumán Province, which is considered middlePaleocene (Soria, 1988a, b). Unfortunately the upper molar mor-phology is not sufficiently preserved in the Requisia remains toallow meaningful comparison (and apparently, not all the mate-rials assigned to this taxon unquestionably belong to it), but asimilar development of the parastyle and metastyle is seen in thepremolar. In contrast to Raulvaccia, the selenodont M2 of No-tonychops (PVL 4298) in occlusal view is longer labio-linguallyand shorter mesio-distally in occlusal view, and the mesial anddistal cingula are straight, not arched. The parastyle is locatedmuch more labially with respect to the paracone, but in Raul-vaccia, as in Escribania, the parastyle is aligned mesio-distallywith the paracone and metacone.

DISCUSSION

A preliminary phylogenetic analysis was performed to test thefamily referral of Raulvaccia peligrensis. In addition to Raulvac-cia, the analysis included sixteen ingroup taxa at genera level(four North American Mioclaenidae, five Kollpaniinae, threeLitopterna Protolipternidae, and five Didolodontidae) as well asProtoungulatum as an outgroup. With the exception of R. peli-grensis, the dental characters and their codification were takenfrom Gelfo (2004). Only one character was added to the originalmatrix (Appendix 1) character 28: Outline of the precingulumand postcingulum: (0) almost straight from the labial to the lin-gual side. (1) moderate to strongly arched. All characters weretreated as unordered and equally weighted. An exhaustivesearch was performed using the implicit enumeration option ofTNT software (Goloboff et al., 2003). The analysis resulted innine most parsimonious trees of 52 steps, the strict consensus ofwhich is 59 steps long (Fig. 6) with a consistency index (CI) of0.57, and a retention index (RI) of 0.74. The tree shows mono-phyly of the Kollpaniinae, in contrast to all previous analyses(Muizon and Cifelli, 2000; Gelfo, 2004) where this group ap-peared as paraphyletic. However, there are no unambiguous sy-napomorphies diagnosing the Kollpaniinae, which are supportedby two derived characters, the distal slope of the metaconid,strongly inflated and invading the talonid basin (Character 23);and the large and conical hypoconid, extending in the lingual halfof the talonid (Character 25). The paraphyly of the Protolipterni-dae is due to the absence of tarsal characters in the data matrix,so this analysis does not by itself support the issues about thevalidity of the family (see comments in Gelfo, 2004). The Di-dolodontidae are a monophyletic group, supported by one ex-clusive derived character, the presence of hipocone in the lastmolar (Character 5). Despite the previously mentioned limita-tions of this preliminary analysis, it supports the phylogeneticposition of R. peligrensis outside of the Kollpaniinae, and theirclose relationship with the Didolodontidae.

The new specimens described here allow the revalidation ofthe Paleocene taxon Raulvaccia peligrensis in agreement withBonaparte and colleagues (1993), who recognized this taxon asdifferent from the contemporaneous archaic ungulate Escribaniachubutensis.

The discovery of new remains of Raulvaccia peligrensis andEscribania chubutensis (Gelfo, 1999, 2004) show that the mainsimilarities with the Kollpaniinae Mioclaenidae are found in thelower dentition, which seems to be conservative, given the pres-ence of a conspicuous paraconid not fused to the metaconid, andthe projection of the distal wall of the metaconid into the talonid

GELFO—PALEOCENE ‘CONDYLARTH’ FROM ARGENTINA 657

(Character 23 of the phylogenetic analysis). In contrast, the maindifferences are in the upper dentition, due to the presence of astrong hypocone and parastyle. In contrast to the plesiomorphiclower molars, the upper molars of Raulvaccia and Escribaniaseem to be derived with respect to the Kollpaniinae, and com-parable to those present in the Didolodontidae. For that reasonand for the explained differences with the Protolipternidae, R.peligrensis is considered as a member of the Didolodontidae, aswas earlier argued for E. chubutensis (Gelfo, 2004). The noveldevelopment of a large parastyle in Raulvaccia and Escribania,represents a structure unknown in later Didolodontidae, inwhich this cusp is always smaller, if present at all.

The recognition of a monophyletic origin of the South Ameri-can Tertiary mammals, since the proposal of the Grand OrderMeridiungulata (McKenna, 1975) has been long debated (Mc-Kenna, 1981; Cifelli, 1983; Novacek, 1986). In contrast with Lu-cas (1993) who considered that the Pyrotheres, including theXenungulata, are not Ungulata. Soria (1988b) considered themonophyly of the South American Tertiary ungulates as highlyprobable, derived from a basal group closer to the oxyclaeniinearctocyonid ‘Condylarthra.’ This group should have arrived toSouth America in the last part of the Senonian, and diverged intotwo major lineages, one for the Astrapotheria, Notoungulata,

Xenungulata and Pyrotheria; and the other for the Didolodon-tidae and Litopterna. Perutherium altiplanense from LagunaUmayo in Peru, with an age considered now more probablyrelated to Cron 26r, that is, the lower part of the upper Paleocene(Sigé et al., 2004), was proposed as part of the ‘arctocyonidstock,’ ancestral to the Meridiungulata (Soria, 1988b), but now isconsidered as an Notoungulate (Sigé et al., 2004). So, the bestknown morphological relatives, for the Didolodontidae andLitopterna, are the Kollpaniinae Mioclaenidae. This group fromthe early Paleocene of Tiupampa in Bolivia, and the Eocene ofPatagonia (Gelfo, 2004) possessed a very primitive dental(Muizon and Cifelli, 2000) and ankle structure (Muizon et al.,1998). The probable monophyly of a clade including the Mioc-laenidae, Didolodontidae, and Litopterna, formalized in thePanameriungulata, strengthens the unlikelihood of a single ori-gin for the South American ungulates and therefore questionsthe monophyly of the Meridiungulata (Muizon and Cifelli, 2000).

If the Kollpaniinae are the basal group of the Panameriungu-lata, as they seem to be (Muizon and Cifelli, 2000; Gelfo, 2004),the discussion of the relative age of the Tiupampan and PeligranSALMAs becomes particularly contentious with respect to theinferences of Marshall and colleagues (1997), who argued for theolder age of the Peligran. In fact, in contrast to Peligran, in theTiupampan SALMA the ‘condylarths’ have an extremely primi-tive morphology, comparable to those of the Puercan NALMA,and neither the Didolodontidae nor the Litopterna, so charac-teristic of the Cenozoic in South America were present.

In the same context the presence of a single tooth probablybelonging to a Notoungulata in the Paleocene of Tiupampa(Muizon, 1992), seems to be in agreement with an earlier ungu-late radiation not related to Panameriungulata. As the notoun-gulate record in Patagonia seems to be much younger than innorthern South American latitudes the presence of this taxon inthe lower latitudes of Tiupampa could indicate a different sce-nario for the evolution of the ungulate communities, one geo-graphically distinct from that of Patagonian areas where the Di-dolodontidae and Litopterna have an older fossil record.

The Peligran fauna also seems to be a good assemblage to testpatterns of ecological replacement in the fossil record. For ex-ample, those in which competition from a replacing group causedthe extinction of another group; or those patterns in which thedisappearance was triggered by a mass extinction produced byother causes (Benton, 1987) like those collectively known as theCourt Jester hypotheses (Barnosky, 2001). If the known Creta-ceous-Tertiary fossil record for the dryolestids and eutheriansare compared, they seem to have a double-wedge pattern inwhich the shapes of the two clades are negatively correlated. Inaddition to their synchronous record, they also show a similartrend of the cheek teeth morphology, which were bunodont andseem to have increased the crushing surface by the PeligranSALMA. In the Dryolestida this achievement was consequenceof the strong inflation of the teeth and the hypertrophy of someof them, leading to a large crushing paracone as the one presentin Peligrotherium tropicalis (Gelfo and Pascual, 2001). In con-trast to the dryolestid paracone, the Peligran didolodontids, suchas Escribania or Raulvaccia, did not develop a unique strongcrushing cusp. In addition to the protocone, as in their Kollpa-niinae counterparts, they developed a distolingual cusp, the hy-pocone, which seems to be particularly specialized in the M3 ofEscribania (Gelfo, 1999). This fact does not by itself confirm com-petition, but opens an interesting hypothesis for future testing.

ACKNOWLEDGMENTS

A team from Museo de La Plata directed by Rosendo Pascual,found in 1990 the remains described here. I’m grateful to Mari-ano Bond and Edgardo Ortiz-Jaureguizar for their useful discus-sion of several topics related to this paper. Cecilia Morgan andMichael Woodburne improved the English of an earlier version

FIGURE 6. Strict consensus (L:59, CI:0.57, RI:0.74) of nine most par-simonious trees (L:52) using the implicit enumeration option of TNTsoftware. 1 Kollpaniinae node; 2 Didolodontidae node.

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of this paper. I thank the curator Alejandro Kramarz (MACN)and Christian de Muizon (Muséum national dHistoire Naturelle)for permission to study the materials under their care. Christiande Muizon also discussed with me several aspects of the relativeage of Tiupampa. I also thank Agustín Viñas who drew thefigures. The manuscript benefited considerably from commentsby Bruce Shockey, Lilian Paglarell; Bergqvist, and one anony-mous reviewer. I’m indebted to Marianna B. J. Picasso for her per-manent support. All of these scientists do not necessarily agree withthe contents of this work, for which I am solely responsible.

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Submitted March 13, 2006; accepted March 30, 2007.

APPENDIX 1. Character taxon matrix used for phylogenetic analysis.

1–10 11–20 21–28

Protungulatum 0001000001 0001000000 01000110Promioclaenus 1100010101 1221000001 01010110Litaletes 0101010101 0221101011 01010110Protoselene 0201011101 0111001001 02010110Mioclaenus 0011?11101 1221000000 01010120Molinodus 0000010101 1111010011 12111110Tiuclaenus 0000020101 1221010000 12111110Pucanodus 0000020101 1221010000 12111110Simoclaenus ???0010101 1111010011 12111110Anidinodus ?????????? ?????????? 12111110Escribania ???2110112 1221120??? 12121111Lamegoia 1212130112 1221120?11 12011110Paulacoutoia 1212130112 1221120011 12021110Didolodus 1212111112 1221120111 12021110Miguelsoria ??12030112 1221120111 12010110Protolipterna 1212030101 1221120111 12010110Asmithwoodwardia 1212030101 1221020111 12010110Raulvaccia ???2?10112 1221120??? 12021111

The characters and their codification were taken from Gelfo (2004).Missing characters states are indicated by question mark (?).

JOURNAL OF VERTEBRATE PALEONTOLOGY, VOL. 27, NO. 3, 2007660