Reu. Mus. Argentino C~enc.Nat., n.s. 6(2): 257-305,2004 Buenos A~rca,ISSN 1514-5158

Late Cretaceous vertebrates from Bajo de Santa Rosa (Alien Formation), Rio Negro province, Argentina, with the description of a new sauropod dinosaur ('ll'itanosauridae)

Agustin G. MARTINELLI' & Analfa M. FORASIEPI' "

'Museu Argentino de Ciencias Naturales -Bernirrdino Rivadavia., Av A. Gallardo 470, C1405D.m Bilenos Aires, Argentina. [email protected]. zl)epartment of Anatomical Sciences and Neurobioloa, University of Louisville. I,ouisvillo, Kentucky (40292), IJSA, [email protected]

,4bstraet: A large and diverse collection of vertebrate remains from the Campanian-Maastrichtian Allen For- mation (Malargiie Group) at the Bajo de Santa Rosa locality (Rio Negro Province, Argentina) is described hore. The vertebrates arc represented hv: chondrichthvans: di~iomvstidsiluriform. le~isosteid,cf oercichthvid and titanosaurid dinosaurs. A now small salt,asaurinetit&saurid, I3onatitan reigigen. el sp. no"., is described. It is diagnosed by the following association of characters: 1) longitudinal groovo located an the suture between pari- otals that continues posteriorly over the supraoccipital to the foramen magnum; 2) basisphcnoid tubera long and narrow; 3) dorsalto middle caudal vertebrae with deep oval to circular pits present on both sides of the prespinal lamina; 4) anterior caudal vertebra with spino-postzygapophysiat and spino-prezygapophysiai lami- nae; 5) neural arch of anterior caudals with deep interzygapophysial fossae with numerous pits; 6) anterior caudal vertebra with an accessom sub-horizontal lamina extendine" from the antero-ventral oortion of the postzygapophysis to the mid-portion of tho spino-prezygapophysial lamina; and finally, 7) anterior caudal verto- bra with a prominent axial crest on the ventral surftaee of tho cerntrum. The first rocord of sphenodonts and cf carcharodontosaurid theropods is recognized for the upper Late Cretaceous ofpatagonia, as well as the earliest record of perichthylds (Pereiformes). The vertebrate record is mainly composed of terrestrial and freshwater tawa, but a few marine elements are found (olasmosaurids) indicating a marine influence during the deposition of the Allen hrmation in the arca of Baio de Santa Rosa. The vertebrate remains su~~orta Cam~anian- and extra Patagonlan South Amencan records

Key words: Late Cretdecous, osteichthyans, chondnchtllyans, anurans, turtles, sphenodonts, plesiosaur^, oph~d- ians, dmosaurs, Patagonla

., " particular those of Argentina, is opening new ince, Argentina; e.g., Bonaparte et a;., 1984; windows, not only for the infornlation based on Bonaparte, 1986a,1987, 1990, 1992, 1994,2002; new taxa, but also for the evolutionary, paleobio- Baez, 1987; Broin, 1987; Albino, 1986, 1994; geographic, biochronoiogical, and compositional Cione, 1987; Salgado et al., 1997b), Loncoche aspects of the Late Cretaceous continental as- (Mendoza Province, Argentina; e.g., Wichmann, semblages which populated this continent. The 1927; Gonaaez Riga, 1999),Allen (Rio Negro and fossil remains recovered fkom the Campanian- La Pampa, Provinces, Argentina; e.g., Powell, Maastrichtian South American formations such 1987b, Gasparini & Salgado, 2000; Salgado & as Los Blanquitos iSalta Province, Argentina; Aspilicueta, 2000; Coria, 2001.), La Colonia e.g., Powell, 1979,20031, Lecho (Salta Province, (Chubut Province, Argentina; e.g., Ardolino & Argentina; e.g., Bonaparte & Powell, 1980; Franchi, 1996; Albino, 2000; Gasparini & de la Chiappe, 19931, Yacoraite (Salta Province, Argen- Fuente, 2000; Pascual el al., 20001, El Molino tina; e.g., Powell, 1979; Cione et al., 1984; Cionc (Central and South Bolivia; e.g., Gayet et al., & Pereira, 1985; Benedetto & Sbnchez, 1971; 1991,2001,2003; Gayot, 1991; Schultae, 1991a & 258 Revista del Museo Argentina de Ciencias Notu~.ales,n. s. 6 12i, 2004 h; Gayet & Meunier, 1998):AdamantinaandNdriiia age is presumed to be Coniacian-Santoniari (Mints Gerais and Sio Paulo States, Brazil; e.g., (Legarreta & Gulisai~o,1989; Bonaparte, 1991). Gayet & Brito, 1989; Bertini el al., 19931, aild fi- The Allen and Jagiiel Sormations that correspond nally Asencio and Mercedes (Paysandi~,Rio Negro, to the Malarae Group overlie discordantly the Durazno and Soriano localities, Uruguay; e.g., Bajo de la Carpa Forrnation. According to recent Mones, 1997) show a great taxonomic diversity of studies (Hugo & Leanza, 2001) both the Bajo de vcrtehrates in Gondwana. Pa Carpa and Jaguel formations are poorly rep- In addition, Campanian-Masstrichtian noii- resented at the Uajo de Santa Rosa locality; con- South American Goridwanan vertebrates have trary, the Allen Formation shows widely exposed been found in India (e.g., Lydckker, 1877, 1879, outcrops (Fig. IB). 1887; Huene & Matley, 1933; Berrnan & Jain, The formations that comprise the Malargue 1982; Jain & Bandyopadhyay, 1997). Madagas- Group (late Camparlian-Early Paleocene sensu car (e.g.,DepC.ret, 1896; Krauseetal., 1997,1999; Legarreta & Gulisano, 1989) vary according to Curry Rogers & Forstel; 2001; Gottfried and their position in the Neuquen basin. In the south- Krause, 1998; Sampson et al., 19981, and, though east of the hasin the sedimentary sequence com- lcss abundant, in Australia (e.g.,Rich et ul.,2002), prises (from Llie base to the top respectively) tile New Zeland (e.g., Moliliir, 1989), and Antarctica Allen, Jagiiel, Roca, and El Carrizo formations. (Gasparini & Goiii, 1985; Olivero et al., 1991; In the northwest of the basin the Malargze Group Novas el al., 2003ai which also contribute to the is formed by the following units: I,oncoche, knowledge of the diversity of Gondwansn biota. Jagiiel, Roca, and Pircaia Sormations (c.g., Bar- During ttie summer of 1990, 1.991, and 1994 rio, 1990). fieldworks direct.cd by Dr. Jos6 I? Bonaparlo arid The Jagiiel Formation overlies the Allcri For- carried out by staff from the Museo Argentino mation in t,he area oS Bajo de Santa Rosa. The de Ciencias Naturales *Bernardino Rivadaviam age inferred for the Jaguel Formation is Late were conducted at the Bajo de Santa Rosa local- Maastriclitian-Early Danian (e.g., Casadio, 1994); ity. Rio NegroProvince, Argentina (Fig. 1).Arich the Crctaceous-Pilleocene transition (I<-Ti was and diverse collection of vertebrate remains was recognized in the upper part of the sequence recovered from outcrops of the Allen Formation (Coiichcyro et al., 2002). (Table 1). These fossil reinairis identified are: The Allen Formation is the first iitostra- chondrichthyans; diploinystid siluriforrns, tigraphic unit of the Malargiie Group, Malal- Iepisosteid, proi~abiypercichthyid, and dipnoid hueyano cycie (Riogridico supercycle) corre- osteichthyans; pipid and leptodactylid anurans; sponding to the first Atlantic transgression (.Mar chelid turtles; sphenodonts; elasmosaurid plesio- dc KBwasn; Casarniquela, 1978) into the Neuqu6n saurs; madtsoiid snakes; and hadrosaurid, Basin (c.g.,Wichmann, 1927; Casamiquela, 1978; titanosaurid, and probably carcharodontosaurid Bertels, 1979; Uliana & Dellape, 1981). The At- dinosaurs (Table 2). lantic ingression extended over northern Ttie aim of'this contribution is to describe the Patagonia (roughly correspondiiig to the limits vertebrate fossils collected from the Allen For- of the IZio Negro and Neuqu6n Provinces) reach- mation at the Bajo de Santa Rosa locality (Fig. ing the south of Mendoza and La Pampa Prov- I), and to report a new saltasaurine dinosaur, inces (e.g., Casamiquela, 1978; LTliana & Dellape, Honatitan wig2 gen, et sp. no". Comments and 1.981; GonzBlez Riga, 1999; GonaAlez Riga &

I I.,... :I. ,. ' Ii- \,.:ill ti:< l i..I. I..I I- Casadio, 2000). !,1.29i. t.. ! ( .:,[!I 11: .I1 ...:.- I! !,. The The Allen Formation named initially Soutll Americii are discussed <

~ahie1. List of tho specimens studied. An asterisk (9indicates holotypo sprcinien.

SPECIMEN 1I)ENTIFICATION MATERIALS - MACN-PV KN 107'2 Diploniystidae indet. 4 incomplete pectoral spines MACN-PV RN 1.074. Siluriforiiies indet. 4 incomplete pectoral spines MACN-PV RN 1084 Siluriformes indet. iircomplete pectoral spine MACN-PV RN 1071 Lepisosteidae indet. 6 vertehral cenrra NIACN-PV RN 1077 Teleostoi irrdet. 10isolated teeth MACN-PV IZN 1081 e/ Perciehthyidae indet. 19 fragmentary vertebrae h4ACN-PV RN 1079 Ceratodontiformes indet. tooth plate MACN-PV RN 1080 Ceratodontiformes indet. 2 tooth plates MACN-PV RN 1076 Chondrichthyes indet. 1.1 vertebral cuntra MACN-PV RN 1064 Pipidae indet. sphenethmoid .WCN-PV RN 1065 Pipidae indet. sphenethmoid .MACN-PV HN 1063 Leptodactylidae irzdet. fragment of maxilla NIACN-PV RN 1069 Leptodactylidae ir~det. 23 Ragments of ornamented cranial bones MICN-PV RN 1066 Leptodactylidae indet. incomplete right iiumcrus W\CN-PV RN 1067 Anura indet. 5 incoinpieto vertebrae NMCN-PV RN 1068 Anura indet. 5 iiieomplete angulosplenials WN-PVRN 1070 Anura indet. radio and ulna IMACN-PV RN 1089 Chtlidac indet. fragments of caparace MACN-PV RN 1090 Chelidae indet. fragmeilts of caparace MACN-PV RN 1091 Chelidae indet. fragments of caparace MACN-PV RN 1087 Elssiuosauridae indet. 3 cervical and 1 caudal centra, and fragmentary remains .WCN-PV RN 1062 Sphenodontidae indet. fragmcnt of right lower jaw MACN-PV RN 1049 Patagoniophis paruus incompleLe trunk vertebra MACN-PV RN 1056 Patnguniophir paruus iiicomplote trunk vertebra WICK-PV RN 1053 Alarnilophis argentii~i~s incomplete trunk vortobra MACN,PV RN 1051 Madisoiidae indel. incomplete trunk vertebra MACN-PV RN 1052 Madtsoiidae indet. incomplete trunk vertebra MACN.PV iZN 1054 Madtsoiidae inclet. incornpieto trunk vertebra MACN-PV RN 1059 7Madtsoiidac irrdet. incomplete trunk vertebra 'MCN-PV RN 821 Bonatitan migi complete hraincase, middle dorsal vertebra, anterior caudal vertebra, middle caudal ncural arch, loft liumerus, Cra~mentolmetacarpal, both femora, hoth tihihe, left fibula, left ealcancous, left metatarsal I MACN-PV RN 1061 complete braincase, incomplete anterior eervicalvertebra, left radius, left ulna, left fomur, left tibia, calcaneoiis, metatarsal 111, and fow ineompletc chevroris MACN-I'V RN 1088 Sphaerovurn erbeni 7 oggs arid several fragments of eggshell MACN-PV RX 1096 Mcgalaolithidao ilrdet. 8 eg.9 and fragments of eggshell MACN-PV RN 1086 ef Carcharodontosauridae indet. isoisted tooth MACN-PV RN 1085 Hadrosauridae indet. 5 fregments of maxilla and tooth fragments

Paleoenviromentai studies of the Allen Formd- mudstones with small lents of conglomerates. tion suggest the presence of a fluvial environment The upper rneniber is dominated by gray pelites in the basal section; becoming suhtidal with conti- covered by limestone and gypsum (Page et al., nental influence in the middle; and finally, a ma- 1999; Hugo & Leanza, 2001.). ririe regression is represented in the upper section, All tho specimens described here (Table 1)wore with the evaporation of shallow lagoons close to collected in the lower member of the Allen For- the sea (Andreis et ul., 1974; Uliana and Dellapb, matiori exposed at Bajo de Sarita Rosa (Fig. 1). 1981; Barrio, 1990; Casadio, 1994,Pageet al.,1999). Institutional Abbreviations. MACM: The Allen Formation at Bajo de Santa Rosa Museo Argentino dc Ciencias Naturales ..Bernar- consists of two rnemhers each about 70 meters dino Rivadavia>>(CH, Chubul Collection; N. thick (Hugo 85 I,eanza, 2001). The lower mem- Nouquen Collection; PV, Paleontologfa de ber is composed of alternated sandstones arid Vertebrados; RN, Rio Negro Collection). 260 Reuista del Museo Argentina de Cie~iciasNaturales, n. s. 6 121, 2004

Tahlo 2. Systematic list of tho veriebrales describedhere Crom the Allen Formarion at tho Raja de Saiita Rosa locality (Rio Negro Province, Argentina).

CLASS CHONDRICHTIIYES Subclass ijiapsidu Ordcr indet. lnfraciass Lopidosauromorpha Superorder Lepidosaiiria CLASS OSTEICI-ITIIYES Order Spl~eiiodontia Subclass Aclinopierygii Pa~nilySphenodontidae Superordcl. Teleoslei Ceri, el ;i.indet. Order indet. Ordcr Squamata Order Siluriformcs Subordcr Serpenlos Family Diplomystidac l%mily Madlsoiidae Ge,:, el s;>, indct. Alainitophis argentini~s Family indet. Pctagoi~iopl~isparuzis Superorder 6.i-Iolostei- Gen. el sp. indet. Ordor 1,episoscoifarmes Family ?Madtsoiidao Family Lepisosteidac Gen. ~'tsp. il~del. Gen, el so. indet. Superorder Acarithopterygii Order l'erciformes Superorder Sauropterygia Family c/: Perciclilhyidae Order Plesiosaurii~ Gen, el sp, ii~det. Fanlily F>losmosauridae Subclass Sarcopterygii Gc~L.ei sp. indet. Order Ccra!odontiibrmes Family Ccretodontidae Geri. et sp. iiidat. CLASS AMPIIIBIA Ordor Saurisquia Ordcr Anura Suborder Theropoda Family Pipidae Family cf Cvrcharodonlosauridae Gen, 6.1 sp. ~ndet. Ger~.et ,sp, indet. Family Leptodactylidac Subordei Saurapoda Gen, el sp, indct. Family Titanosauridae Family indet. Subfamily Saitasaurinae Bor~ntitar~reigi gut, el sp. noo. CLASS REPTILIA Ooikmily Faveoloolithidae Subclass Testitdinata Sphneroui~merbani Order Clielonivl Oofainily Megalooliikiidao Suborder Pleurodira Gcn, et sp. ilcdet. Family Chelidile Ordor Ornilliisquia Gcri et sp, indet, 1 Suborder Orni!.opoda Ge,, et sp. indet. 2 E'amily Iiadrosauridae Geri, ct sp. indet. 3 Gen. et sp, indet.

SYSTEMATIC PALEONTOLOGY 1989; Bertini et al., 1993), and continental Creta- ceous-Early Tertiary ibrniations of Bolivia (e.g., OSTEICIITHYAVS Gayet, 1991; Gayet & Meunier, 1998).

Freshwater osteiclithyan remains are a com- Ostcichthyes IIowes, 1894 mon element in the lower member of the Allen Siluriformes (sensz~Chardon, 1968) Formation at Bajo de Sarita Rosa. Despite the frag- mentary and isolated nature of these specimens, Cretaceous freshwater siluriforms are kriown at least five families were recornized. Comnari- in South America onlv,, hv" fraementarv" and iso- sons with previously known taxa wero carried out, lated remains. They were reported in the Late specially with those fishes recovered ill the Cali Cretaceous Yacoraite Formation (Salta Province; Taro, Yacoraite, 1,os Alamitos, and Loricoche for- Cione & Pereira, 1985; Cione el al.. 1984), Coii mations (Cione & Laffite, 1980; Cione & Pereira, Toro, Los Alamitos, and Ida Colonia forrnatioris 1985; Cione et al., 1984; Cione, 1987; GonzAlez (Pdtagonia; Cione & Laffite, 1980; Cione, 1987; Riga, 19991, the Bauru Group (Gayet & Brito, Bovcoi~,2002), El Molino Formation (Bolivia; Fig. 1. .I.Location map ofthe Bajo de Santa Rosa locality, lZio Neb~oProvince, Argentina; B. geological map at Bajo de Santa Rosa (modified from Hugo & Loanza, 2001). Regular dots indicate the outcrops ofthe Bajo de la Carpa Fori~~ation;grey pattern indicates the Allen Formation; and horizontal stripes indicate tlie Ja~iielFormation. The arrow shows outcrops at Bajo dc Santa Rosa where thefossils were collected.

Wena, 1969; Gayet & Meunier, 1998; Gayet et d., as it is present in the Uiplornystidae f'om the 2001), and in the Baurn Group (Brhil; Gayet & Maastrichtian of Bolivia (Gayct & Meunier, Brito, 1989; Bertini et al., 1993). Non-South 1998). The denticies are developed only on the American Cretaceous silnriSorms are known from posterior margin; they are smulier and inore the Maastrichtian of Niger (Patterson, 1993), roiinded than in the indeterminatc siluriform Spain (de la Pena & Soler-Gnijbn, 1996), India MACN-PV RN 1074 (Fig. 2C). The deiiticles be- (Cione & Prasad, 20021, and possihly United gin at a short distance of the large posterior fora- States (Frizzell & Icoenig, 1973). men Up to now, the only Ljrnilies recognized in Cominents. The Diplornystidae is an aricit?nt the Cretaceous of South America are the group oSSiluriformes erideinic of South America Diplomystidae, Ariidae, Andinichthyidae, and (Cione, 1987) which was also reported in the Late possible Doradidae, but due to the Sragrnerittary Cretaceous of Los Alamitos (Cione, 1987), La nature of most of the specimens referred to Colonia (Bovcon, 20021, and El Molino formations tlicse families, further studies and inaterials (Gayet & Meunier, 1998). are required to confirm these interpretations (Arratia & Cione, 1996; Cione & Prasad, 2002). Siluriformes (sensu Chardon, 19621) incertne sedis Diplomystidae Eigeriman 1890 (Figs. 2B, C) Cen, el sp, indet. (Fig. 2A) Referred Material. MACN-PV 1ZN 1074: four very small incomplete pectoral spines (Fig. 2C). Referred Material. MACN-PV RN 1072: four MACN-PV RN 1084: iincomplcte pcctoi.ai spine incomplete pectoral spines. lacking its proxinial portion (Fig. 213). liescriptiota. All the pectoral spines have well Deswiplio~~.Dospite their Eragmeiitary ina- developed radial striae on the proximal articular ture, tlnese remains show differences with the surfaces and lack nn ant.crior deilticulatiori (di- catfish (Diplornystidae) reinains cornrneinted agnostic features of Diplomystidae; Gayet & above. The speciirien MACN-PV RN 1084 repre- Meunier, 1998). The specimen herein figured sents the largest siluriform Rom Bajo de Santa (Fig. 2A) has an elongate dorsal process (follow- Rosa (Fig. 2B). Tlie spine is slightly curved, lacks ing tlie terininology of Huhbs & Hibbard; 1951) aiiterior deiiticles, wit11 the small postcrior ones articular facet

Fig. 2. Osteichthyans. A. MACN-PV XN 1072, right ptxtoral spine ofUiplornystidae indet. in posle- viol; dorsal and anterior views; B. MACN-PV liN 1084, fragment of pectoral spine of Siluriforrries indet. in dorsal and posterior views; C. MACN-PV RN 1074, fragment of pectoral spine of Silurilormes indet, in dorsal view; U. MACN-PV RN 1071, vertebra oSLcpisosteidae indet. in dorsal, anterior and ventral views; E. MACN-PV RN 1077, tooth plate of Telcostei indet. in occlusal and lateral views; P MACN-PV RN 1081, anteriormost vertebra ofcf Pcrcichlhyidae indet. in lateral view; G. MACN- PV 1081, vertebra of cf Percichthyidac indet. in lateral and anterior views; H. MACN-PV RN 1079, tooth plate of Ceratodontiformes indet, in occlusal view; I. MACN-PV XN 1080, tooth plate of Ceratodontiformes indet. in occlusal view. Chondrichihyans. J. MACN-PV RN 1076, vertebra of Chondrictithyes indet. Scale bar represents 5 mm. Grey pat,tern indicates broken areas. Martinelli & Forasiepi: Late Cretaceous vertebrates from Rio Negro, Argentina 263

located in a longitudinal groove. The spine is al- ered it to be Teleostei incertae sedis (Cione, per- most circular in cross-section and the dorsal and sonal communication in GonzBiez Riga, 1999). ventral surfaces are covered with shallow loogi., tudinal furrows. Perciformes Bleeker, 1859 In the Cour specimens catalogued as MACN- cf Perclchthyldae Jordan & Eigenman, 1890 PV RN 1074, the proximal portion of the spine Gen. et sp. indet. 1s missing. The denticles are located only on one (Figs. 2F-G) edge (possibly the posterior margin); they are sharp, inclined, and as long as the spine width ReferredMuterial. MACN-PVRN 1081: nine- (Fig. 2C). A similar type of pectoral spine has teen fragmentary vertebrae. been also discovered in the siluriforms from the Description. One of these remains corres- Los Alamitos Formation (Cione, 1987: Fig 1B). ponds to ail anteriormost vertebra due to the At the moment, these fossil remains are re- presence oi' the articular surface for the ferred to Siluriformes incertae sedis. At least exoccipital (only preserving the right one), which three different morphologies were identified that kces antero-dorsally (following Arratia, 1982) could be related to different siiuriform taxa. The neural arch and spine are autog(+nous.The postzygapophyses are broken offand behind this Lepisosteiformes Hay, 1926 region there is a large circular depression possi- Lepisosteidae Cuvier, 1825 bly for rib articulation (Gayet, 1987; Fig. 2F). Thc Gen. et sp. indet. anterior surface ofthe centrum is larger than the (Fig. 2D) posterior one. In all ccntra (Figs. 2F, G), there are numerous deep cavities of different shapes Referred Material. MACN-PV RN 1071: six and sizes on the lateral and ventral surfaces, vertebral centra (Fig. 2D). separated by bony trabeculae (Figs. 2F, Gj. The Description. At least six incomplete vertebrae vertebral centra range frorri 2 to 9 millimeters in were found at Bajo de Santa Rosa. The vertebral diameter. apophyses have not been preserved in most speci- Comments. The autogenous neural arch is a mens. All the vertebrae show the diagnostic fea- characteristic feature of the Perciformes (Gayet, ture of Lepisosteidae in having an opisthocoelous 1987). The pattern of ornamentation with deep centrum (Cione, 1987). cavities in the vertebral centra is common in two Comments. In South America, lepisosteids families of Perciformes: Ccntropomidae and have been documented in the Late Crctaceous Percichithyidae (e.g., Arratia, 1982; Gayet, 1987, Banru Group (Gayet & Brito, 1989;Bertini et al., 19911. The Centropomidae are tentatively recog- 1993), El Molino (Gayet et al., 20011, Los nized in the Paleocene of Tiupampa (Bolivia) Alamitos (Cione, 1987; El Abra locality, Gayet et (Mi~izonet al., 1983; Gayct, 1991; Arratia & Cione, al., 1.991.), and Loncoche (Gonztilez Riga, 1999) 19961, while the Percichthyidae are known Srom formations. The earliest records of this family the Maastrickitian of Bolivia (Gayet & Mcunier, have been found in the Early Cretaceous of AG 1998; Gayet et al., 2001), the Eocene and Miocene rica (Paralepidosteus africanus; Aramhourg & of Argentina and Chile (Schaeffer, 1947; Arratia Joieaud, 1943) and Brazil (Obaichthys; Wenz & & Cione, 1996), and Oligocene-Miocene of Brazil Brito, 1992). (Arratia, 1982). Rornains tentatively rererred to Centropomidae or Percich-thyidae were also re- T(?leosteiMiiller, 1844 ported from the Marilia Formation (Bertini et al., incertae sedis 19Y3), but further studies must be performed to (Fig. 2E) clarify their taxonomic status. The living Eresh- water Percichthyidae are represented by six spe- Referred Material. MACN-PV RN 1077: tcn cies belonging to the genus Percichthys that in- hemispherical teeth of different sizes. habit the southern and western regions of Argen- lJ,,, ,,.,,,!j ,u. IC<.III;ire I k!~~i.~l~l,vf1~.,~1;t(.~l 11:l.t .I$ (I ( i.11~ c. L: . .\rt.,tlt.~, !>,.2 Y . <;v ~~~rcul,ir.sl~;,~,,.~lA .-Fi:. 21.: . 'Y'l.,.~r ~I!.I!II,,IV~.< \r$ \ . I... I I zt II.: &om 6 to 15 millimeters. Santa Rosa to the basal family of percoids Comments. Similar teeth, although smaller, Percichthyidae because they share a similar ver- have also been found in Los Alamitos and tebral morphology with those Percichthyidae Loncoche formations (Cione, 1987; GonzBlez such as Macquaria antiquus (Gayet, 1987) and Riga, 1999). This kind of tooth was originally the living Percichthys trlicha (Arratia, 1982 181, assigned to Semionitidae (?Lepidotes sp.) or especially in the morpholo&yofthe anteriormost Sparidae (Cione, 1987) but later studies consid- vertebra. Thesevertehralremains from the Allen 264 Reuistu del ~WuseoArgeniino de Ciencias A'olz~rales,n. s. 6 (2), 2004

Formation possitbly rt?presentthe earliest record Martinet a!., 1999) and they are abundant in the oS Pcrcichtliyidae in the Canipanian-Maas- Late Cretaceous fossil record ofArgent.iria (e.g., i.rich1ian of South America. However, a wide- Ameghino, 1899; Wichmann, 1924, 1927; Pascual range of comparison among other basal families & Bondesio, 197ii; Cione, 1987; GonzBlez Riga, orpcrcoids rnust be done Lo clarify the taxononiy 1999).The oldest occurrenceof this group in South of these remains. America conies from the Jurassic of Brazil (Brejo Perciformes have also been found in the Los Santo Formation; Silva & Azcvedo, 1992) and Alalnitos (Cione, 198'i), Loncoche (Gonzalez Uruguay (Tacuarcmh6 Formation; Silva, 1990; Riga, 19991, and Saldefio formations (Salde- Mones, 1997).The taxonomy of the abundant iso- nioicht!i,vs rer1zotiL.s; LSpez-Arbarello et al., 2003) lated tool11 plates discovered ill Argentina is not hut a familiar assignation to these remains has yet resolved, being ..Cerutodi~s>.iheringi tile only not been indicated. formally known species. Several points of view concerning the systematics ofthis taxon have been Dipnoi Muller, 1844 expressed by different aiithors, but a general Ceratodontiformes Berg, 1940 agrcemcnt has not yet been established (e.g., Mas- Ceralodontidae Gill, 1872 tin, 1982; Cioni!, 1987; Kcmp, 1997), therefore we Gen. et sp. indet. rcrer to these remains asgen. et sp, indet. (Figs. 2 H-I) CHONDRICHTHYANS Referred Matel-ia!. MACN-PV RN 1.079: left tooth plate (Fig. 27). MACN-PV RPJ 1080: two Fresliwater choiidrichthyan remains are kriown tooth plates (Fig. 2H). in several Late Crctaceous localities of Argentina, Deacriution. iLlilCN-PV RN 1079 sneci~nenhas Bolivia, Cllile, Peru, and Brazil (c.g., Arratia & four ridges (Fig. 21). The first ridge is the largest, Cione, 1996; GonaAlea Riga, 19996). These records and the others decrease in size toward the medial include Rajiformes and Myliohatifornres (e.g., edge (fi,llowing Llie ter~riiriolo&yof Martin et a/., Arratia & Cione, 1996). At the Bajo de Sani.a Rosa 1999); tlic secorid ridge is broken. The first cn:st localit?: only isolated vertebral centra of is tall and sharp. The lingual and mesial edges are cho~idrichihyanshave been recognized. sligiitly convex, almost similar in length. The oc- cliisal s~irhceis covered with small pits of regular Chondrichthyes Huxle?: 1880 size. MACN-PVRN 1079 resembles the specimens zlacertae sedzs of ~d!errrtodusx from the Bajo de Santa Rosa and (Fig 25) otlier localities figured hy Wichmann (1927: Piate I),tlic specimen of .Pipoidea and the neohatrachian Description. The sphenethmoids probably cor- Leptodactylidae. respond to the same species based on the shared The earliest .ninoid . froe- is Au~tabatrachus morphology and the approximate similar size. The uliar~afrom the Early Cenomanian Candeleros sphenethmoids are arrow-shaped, dorso-ventrally Formation of Rio Negro Province (BBez et al., flat, with two large external narial openings (Figs 2000). Late Cretaceous Pipidae from South 3A, B). The orhitonasal foramina are located at America includes Saltenia ibanezi from the the anterior hail of the sphenethmoid, below a Campanian Las Curtiemhres Formation of Salta distinctive dorso-lateral shelf. The frontoparietal Province (Reig, 1959; BBez, 1981X and the inde- fenestra opens in dorsal view; it is wider than in terminate frog specimens Crorn the Campanian- the Paleocene pipid Shelania (BBez & Trueb, Maastrichtian Los Alamitos Formation (Baez, 1997). The frontoparietal fenestra is anteriorly 1987).This family of freshwater frogs is relatively surrounded by the sphenethmoid, a piesiomorphic well documented in the Paleogene and Neogene trait also present in non-xenopodines and non- of South America (e.g., Estes, 1975; B6ez & pipine pipids (Biez & Pugener, 2003). The nasal Trueb, 1997; BBez & Pugener, 1998,2003). Non- septum is visihle on the anterior margin of the South American records of Pipoidea are found fenestra. In ventral view, a small fragment of the in Africa and range from the Early Cretaceous parasphenoid with the anterior end broken off is to the present (e.g., Estes, 1977; Tisley et al., observable in MACN-W RN 1065 (Fig. 3B); the 1996; Kohei el al., 1996; BBez, 1996),and an iso- specimen MACN-PV 1064 has a shallow depres- lated record from the Oiigoceiie of Yemen (Ara- sion that extends anteriorly for the support of the bian Peninsula; Henrici & BBez, 2001). The liv- cultriform process of the parasphenoid (Fig. 3A). ing Pipidae includes Xenopodinae (Xenopus and In both specimens, the anterior border of this de- Silurana general, and Pipinae Hymenochirini pression is not clear; and a surface for the vomer that inhabits northern Africa, and the genusPipa is not observed. The optic foramen is only pre- (Pipinae) that inhabits the t,ropical regions of served on the left side in MACN-PV RN 1064 northern South America. The fossil record sug- and is fully enclosed by the sphenethmoid. gests a Gondwanan origin for the Pipoidea; the Com,ments. The optic foramen enclosed by the earliest diversification of the extant groups pos- sphenethmoid supports the familiar assignation sibly began during the Cretaceous in Africa and because it is considered a synapomorphy of the South America (e.g., BBez, 1996). Pipidae (Cannatella & Trueb 1988; Bhez & The Leptodactylidae are a paraphyletic assem- Trueb, 1997; Baez & PCgener, 19981, and for that blage of neobatrachian frogs (we use this familiar reason both specimens are assigned to this fam- name until a revision of the taxonomy of the group ily The absence of the vomer could also support is undertaken) that inhabit terrestrial or aquatic pipine affinities kg., BBez & PCgener, 19981, hut environments (e.g., Lynch, 1971; Duellman & as ihe specimens ofBajo de Santa Rosa are poorly Trneb, 1986; Ford & Cannatella, 1993). They are preserved, we prefer to avoid this feature in our recorded in the Los Alamitos (represented by an identification. unnamed taxon closely related to the living teimatobine Caudiuerbera; Biez, 1987) and possi- Neohatrachia Reig, 1958 bly Loncoche formations (Gonziiez Riga, 1999) of Leptodactylidae Berg, 1838 Argentina; and in the Marllia Formation o? Brazil Gen. et sp, indet. (the ceratophryne Baurubatrachus pricei; BBez & (Figs. 3C-E) Perf, 1989). The Leptodactylidae were divarse and are relatively well documented in the Paleogene and Referred Materials. MACN-PV RN 1063: Neogene fossil record of South America (e.g., fragment of right maxilla (Fig. 3C); MACN-PV Schaeffer, 1949; Casamiyuela, 1958; Sigi., 1968; RN 1069: twenty three fragments of ornamented Baez, 1977, 1991, 1996; Bonaparte et al., 1993). cranial hones including incomplete maxillae, and frontoparietals (Fig. 3D); MACN-PV RN 1066: Anura Rafinesyue, 1815 right humerus lacking proximal end (Fig. 3E). Pipoidea Bonaparte, 1831 Description. The fragment of the right max- Pipidae Bonaparte, 1831 illa and the remaining cranial bones are assigned Gen. el sp. zndet. to this family due to the strongly ornamented (Figs. 3A-B) external surfaces. The exostosed cranial ror~f bones are covered with deep subcircular pits o? Heferred Materzal. MACN-PV RN 1064: diverse size (Figs 3C, D); the ornamentation in sphenethmoid (Fig. 3A); MACN-PV RN 1065: tho maxilla decreases near the alveolar border. sphenethmoid (Fig 3Bl. This type of ornameiltation is widely reported in 266 Reulsta del Mz~seoArgentzno de Ciencias Naturales, n. s. 6 (2), 2004

fossil Leptodactylidae such as Baurubatrachus proximal region of the shaft. The distal end is pricei (Bbez & Peri, 1989) and Caudiuerbera wide and the epiphysis is rnainly ossified on the casamayorensi,~(Schaeffer, 1949; Baez, 1977). On radius. The vertebral remains consist of poorly the rnedial aspect of the maxilla, there are high preserved bodies andfrabmentary neural arches, and narrow alveoli; the teeth were not preserved therefore they are not fippred neither compared. (Fig. 3C). The assignation is based upon compari- Comments. No autapomorptiies for family

sori with tine material described from tile Los determination couldhe recoimizedin these~~~ snrci- ,> ~t~ ~ ~- Alamitos Formation (BBez, 19871, Bauruba- mens, so they are regarded as Annra incertae tl~~ch~spricei(BBez & Peri, 19891, and Ceriozoic sedis. It is worth mentioning that in the Pipidae, leptodactylids (e.g., Schaeffer, 1949; BBez, 1977; the coronoid process is blade-shaped (BBez & Casamiquela, 1958), which have the same type Ptlgener, 1998). therefore the angulosplenials of ornamentation. described should correspond to a non-pipid anu- The right humerus (Fig. 3E) is lacking the ran, possihly to the Leptodactylidae. proximal end, and most ofthe deltopectoral crest has been broken off. The shaft is transversely TURTLES narrow and dorso-ventrally wide. The medial and lateral edges diverge distally. The eminentia The major groups of Testudines, the capitata is prominent, simiiar to that seen in the Cryptodira and Pleurodira, have heen docu- Los Alainitos leptodactylids (BBez, 1987),but less mented in the continental Cretaceous beds of developed than in the known Paleocene Patagonia (e.g., Broin & de la Fuente, 1993; de leptodactylids (i.e., taxa from .

/nasal septum

Fig. 3. Anurans. A. MACN-PV RN 1064, sphenethmoid of Pipidae indet. in dorsal and ventral views; B. MACN-PV RN 1065, sphenethmoid of Pipidae indet. in dorsal and ventral views; C. MACN-PV RN 1063, fragment of maxilla of Lept,odactylidae indet. in lingual and labial views; D. MACN-PV RN 1069, fronioparietal of Leptodactylidae ir~det.in dorsal view; E. MACN-PV RN 1066, left humerus of Leptodactylidae indet. in ventral and medial views; E' MACN-PV RN 1068, right anylosplcnial of Anura indet. in ventral view; G. MACN-PV 1.070, riglit fused radio and ulna of Anura indet, in posterior view. Scale bar represents 5 mm. Grey pattern indicates broken areas.

mentary shells and postcranial remains collected are extremely fragineritary and do not allow the in the same locality. The ornamentatiou of the recognition of tile synapomorphies of the cllelids; shells is very similar to that reported in other however, at least three different types of caparaces Chelidae (e.g., Broin, 1987; Gasparini & de la @en. et sp, iitdet. 1,2, and 3)have been recognized Fuente, 2000). Fragments of xiphiplastrons show on the basis of their size arid external ornamenta- the suture for the pelvis as it occurs in all tion. Betier-preserved turtle specimens from the Pleurodires (e.g.,Rroin, 1987; Lapparent de Broin Allen Formation are currently under study (de la & de la Fuente, 2001). The available specimens Fuente, personal communicaiion). fieuisla del Museo Argentina de C,iencias rVc~lurales,n. s. (; 121, 2004

Chelonii Brong~~iart,1800 patagonicus (from the Los Alamitos Formatiori; Pleurodira Cope, 1868 Lapparerit de Broin 8: de la Fucnte, 2001). Nev- Chelidae Gray, 1825 ertheless, based on the fragmentary nature oftl~e Gen. et sp. iizdet. 1 specimens we tentatively corisider them as (Fig. 4A) Chelidae indet.

Refin?3d.Material. IMACN-W IZN 1089:isolated PLESIOSAURS fragments of posterior peripheral caparace. Desci-iption.These specimens correspond to the Most of the available fossil remains of plesio- largest unnamed turtle from the Bajo deSantdRosa saurs in the Cretaceous of South America are locality (Fig. 44.). The ornamentation is slight, with poor and fragmentary (Gasparini & Gofii, 1985; irregular polygons and dichotomized furrows. Gasparirii et al., 2001); the exceptions are few Comrne~zls.This type of siiell ornanmntstion fairiy complete specimens from Chile and is also known in the chelids of the Los Alamitos Patagonia, Argentina (e.g., Casamiquela, 1969; and La Colonia formations (Broin, 1987; Gasparini & de la Fuente, 2000; Gasparini et al., Gasix%rini& de la Fuente, 2000), as well as in 2003a & h). 111 outcrops of the Allen Formation, the large specimens of Chelidae froni t,he Early three incomplete specimens of Elasmosauridae Paleocene of Punta Peiigro (Chubut, Argentina; have been previously described (Gasparini & e.g., Bona et al., 1998). Saigado, 2000). The Elasrnosauridae is a farilily of long necked plesiosaurs found widespread Cien. et sp. indel. 2 around the world during the Cretaceous; never- (Figs. 4B-C) theless, their fossil record is more diverse and abundarit in North America (e.g.,Williston, 1903, Referred Material. MACN-PV RN 1090: iso- 1906; Welles, 1952).Elasrnosaiirid remains were lated fragments of shell. also reportcd in the Lajas (Callovian; c[ Ilescription. These specinlens correspond to Muraenosi~i~rus;Gasparini & Spalieti, 1993), a small to xncdium sized turtle with a heavy or- Agrio (Valanginian-Kauteriviaii; Lazo & namented carapace (Figs. 4B, C). The plates are Cichowolski, 2003), Loncoche (Oonz81ez Riga, thick and hear deep irregular elongated polygons 1999), and Jamel (Gasparini et al., 2003b) for- on the external surface. The fragment of mations. xiphiplastron shows the suture for the pelvis (Fig. 4B), which is considered an autapornorphy of Sauropterygia Owen, 1860 pleurodires (e.g., Broin, 1987; Lapparent de Broin Plesiosauria De Blainville; 1835 8: de la Fuente, 2001). Elasmosauridae Cope, 1869 Comments. A sjniilar pattern of ornariientatiorr Gen. el sp. indel. is observed iri sorne specimens from the Los (Fig 4E) Alamitos (Rroin, 1987),Loncoche (Gonzalez Riga, 1999), and La Colonia [ormations (Gasparini & Referred Muterial. MACN-PV RN 1087: three de la Fuente, 2000). cervical centra, one caudal centrum, and frag- mentary rernains. Gen. ei sp. indet. 3 Description. All the collected specimens are (Fig. 4D) isolated elements; the size varies among them suggesting that these elements correspond to Referred Material. MACN-PV RN 1091: iso- different individuals. The cervical centra have lated fragments of shell. facets for the articulation of tine single-hoaded Description. The rriaterials belong to the ribs; they are latero-ventrally orierited (Fig. 4E) srnallest turtle specirneri collected at Bajo de rather than laterally oriented as seen in the dor- Santa Rosa. The plates are thin and lack sal and caudal vertebrae. The centruni is dorso- macroornamentation (Fig. 4D). ventrally low, antero-posteriorly short, traris- Conaments. This type of shell was reported in verseiy wide, and slightly arnphicoelous. Both the Los Alamitos (Broin, 1987) and La Colonia anterior and posterior art~cularsurfaces are kid- (Gasparini & de la Fuente, 2000) Cormations. This ney-shaped On the ventral surPace twu large fo- specimen could be tentaliveily referred to the ramina are present. Phr-yr~opsgroup; the size and the external sur- The caudal centrum is badly preserved; it is face of the shells resemble Bonaparle~nys dorso-ventrally low, antero-posteriorly short, and bajobarrealis (from the Turonian-Campariiari transversely wide. The articular surface for the Rajo Barreal Formation) and Palaeophrynops rib is oval and laterally projected. Martinelli & Forasiepi: Late Cretaceous uerlebrates fronz Rh Megro, Argentina 269

Fig. 4. Turtles. A. MACN-PV RN 1089, posterior peripheral plate of ChelidaegeteiL. el sp. indet. 1; B. MACN-PV RN 1090, xiphiplastron of Chelidaegen. et sp. indet. 2 in external and internal views; C. MACN-PV RN 1090, pleural plate of Chelidaegen. et sp. indet. 2; U.hlACN-PV RN 1091, peripheral plate of Chelidae gen. et sp. indet. 3. Plesiosaurs. E. MACN-PV RN 1087, cervical centrum of Elasmosauridae indet. in anterior and ventral viows. Sphenodonts. I? MACN-PV RN 1062, fragment of right dentary of Sphenodontia indet, in labial and lingual views. Scale bar represents 10 mm in A- E and 5 mm in F Grey pattern indicates broken areas. Abh~eviations:fr, facet Sor rih; mck, meckelian groove; wf, wear fkcet.

Cornmenls. Rather complete specimens of sphenodontids had been a rare component ofthe elasmosaurids from the middle section of the Mesozoic vertebrate assemblages in South Allen Forniation near the T,ago Pcllegrini (Rio America. in contrast, this group is relatively well Negro Province) were described by Gasparini & docuinel~tedin the Late Triassic to Cretaceous Salgado (2000).These specimens were considen,d beds of Nortli America, Mexico, Europe, China, closely related toElasmosaarusplatyu~~us,a typi- Africa, and India (e.g.,Sues elal., 1994; Rcynoso, cal long-neck plesiosaur of North Arrierica 1997; Fraser & Renton, 1989; Wu, 1994; Sues & (.Western Interior Sean; Welles, 1943) (Gasparini Reisz, 1995; Evarls et al., 2001). & Salgado, 2000; Gasparini et al., 2001). Othcr Lcpidosauria Ilaeckel, 1866

u ithynchocephalia Gurittit!r 1867 (sensu (Late Maastrichtian) and referred to c/: Gautliier et al., 1988) Mauisaarus sp, and Tuarangisaurus'? cabazai Sphenodonta Williston, 1925 (Gasparini et al., 2003b). Sphenodontidae Cope, 1870 (sensn Reynoso, 1996) SPHENODONTS Gen. et sp. indet. (Fig.- 4F) Until recently discoveries of abundant re- mains in the Late Triassic of Braaii (Ferigolo, Referred Material. MACN-PV RN 1062: a 2000: Bona~arte,personal communication) and middle uortiori of the ric~lit- lower iaw. lower Late Cretaceous of' Argentina (Sim6n & Description. Despite its fragmenttary condi- Kellner, 2003; Apesteguia & Novas, 2003), tion, the portion of the dentary preserved indi- 270 Reursta del Museo Argentzno de Czenc~asNaturales, n. s. 6 (21,2004 cates the presence of sphenodonts in the Allen been documented in the Loncoche (Gonzilez Formation at Bajo de Santa Rosa. The dentary Riga, 19991, La Colonia (Albino, 20001, and Los (Fig. 4F) is high and hears a longitudinal depres- Alamitos formations (personal observation). sion on its labial surface. The teeth are fully ac- The Boidae is a group of macrostomatan rodont with flanges (synapomorphic features snakes constituted by Boinae, Pythoninae, shared by this specimen and the crown-group Erycinae, and Calabariinae subfamilies (sensu sphenodonts; Sues et al., 1994). The teeth are lin- Rage, 2001); which are doubtfully documented gually placed and slightly transversely flattened in the Cretaceous of Souti) America. Members of with the main axis mesiolingual-distoiabiaily ori- Boidea were tentatively identified in the Los ented. The distal edge imbricates slightly labi- Alamitos (considered as probable Erycinac and ally towards the posterior tooth, as in other Boinae; Albino 1990, 1996) and La Colorlia kx- sphenodonts (e.g., TingLiana anouolae from the mations (Albino, 2000). Thcse remains are poorly Early Cretaceous of Morocco; Elrans & preserved and tentatively placed in this fiamily Sigogneau-Russel, 19971. The posterior teeth are (Albino, 1990, 20001; therefore, the occurrence larger than the anterior ones. Wear facets are of Boidea duringthis timeframe is not yet clearly present on the tip of the two tallest teeth. The demonstrated. presence of well established wear facets on the The Madtsoiidae have been recovered in teeth is a feature share with Sphenodontidae Soutb America (Campanian-Maastrichtian to (e.g., Reynoso, 2000). Eocene), Africa and Madagascar (Cenomanian to Comments. This specimen represents the first Eocene), Australia (Eocene to Pleistocene), ln- record of Campanian-Maastridltian sphenodonts dia (Maastrichtian) (e.g., Hoffstetter, 1961; Al- in South America, and possibly indicates the per- bino, 1996; Rage, 1987, 1998; Scanlon, 1992, sistence of a gondwanan lineage of Cleuosaurus- 1993; Scalon & Lee, 2000; Gayet et al., 20011, like sphenodonts yet poorly known in the Juras- Spain (Maastrichtian; Astibia et al., 1990; Rage, sic and Cretaceous beds of South America. 1996, 1999), and France (Sige et al., 1997). The Kaikaifilasaurus caluoi (Sim6n & Kellner, 2003) monophyly and phylogenetic relationships of the and Priosphenodon auelasi (Apesteguia & Novas Madtsoiidae among Serpentes are not well estab- 2003; probahlj~ajunior synonymous ofK. caluoi) lished yet (e.g., Scanlon & Lee, 2000; Rieppel et both from t,he Cenomanian Candeleros Forma- al., 2002). Recent phylogenetic analyses piace tion (Neuquen and Rio Negro) are Eileno- Madtsoiidae (with the Australian genus Wonamhi dontinae sphenodonts; they are characterized by as a representative taxonj among basal snakes the presence of a deep dentary and transversely (Scanlon & Lee, 2000), while other interpreta- wide teeth (Sim6n & Keliner, 2003; Apestcguia tions consider that this family has Macrostomata & Novas, 2003), features clearly different from airinities (Rieppel el al., 2002). the specimen from Bajo de Santa Rosa. Herein, we comment the presence of Alamitophis argentinus Alhino, Patagoniophis OPHIDIANS pamus Albino, undetermined madtsoiid remains, and a medinm-siae ?madtsoiid trunk vertebra, The ophidiaus are represented in the Creta- which in our view belongs to a new taxon. In ad- ceous of South America by at least two families: dition, preparation and observation of a new Dinilysiidae, includingDinilysiapatagonica(e.g., trunk vertebra of Rionegrophis madtsoioides Woodward, 1901; Bonaparte, 1991; Caldlvell & Albino from Los Alamitos supports its Albino, 2002) from the Bajo de la Carpa Forma- Madtsoiidae affinities, as was initially interpreted tion (Coniacian-Santonian; Heredia & Salgado, (Alhino, 1986). 19991, and Madtsoiidae, including Alamitophis argentinus (Alhino, 1986, 1.9871, A. elongatus Serpentes Linnaens, 1758 (Alhino, 1994), Patagoniophis paruus (Albino, Madtsoiidae Hoffstetter, 1961 1986,1987), Kionegrophis madtsoioides (Albino, Patagoniophis paruus Albino, 1986 1986, 1987) from the Los Alamitos Formation, (Fig. 5A) and an unnamed species from the El Molino For- mation (Bolivia; Gayet et al., 2001). Alamitophis Relerred Material. MACN-PV RN 1049 (Fig. argentinus was also recovered in the La Colonia 5A) and MACN-PV 1tN 1056: incomplete trunk Formation (Alhino, 20001, and A. sp, cf: A. vertebrae. argentinus and Patagoniophis sp. c/: I? paruus Description. Two well preserved trunk ver- were recognized in the Early Eocene of Austra- tebrae are assigned to Patagoniophis paruas lia (Scanlon, 1993). Indeterminate isolated re- (Fig. 5Aj. These remains share the diagnostic mains probably assigned to Madtsoiidae have also features of II paruus (IIolotype MACN-PV RN Martinelli & Ijorasiepi: Late Cretaceous vertebrales from Rio Negro, Argentina 271

Fig. 5. Snakes. A. MACN-PV RN 1049, trunk vertebra of Patagoniophis paruus Albino in laterai (Al), anterior (A2), posterior (A3), dorsal (A4) and ventral (A51 views; B. MACN-PV RN 1053, trunk vertebra of Alarnitophis argentinus Albino in latcral (Bi), anterior (B2) and ventral (B3) views; C. MACN-PV RN 1052, trunk vertebra of Madtsoiidae indet. in posterior (Cl.),lateral (C2), dorsal (C3) and ventral (C4) views. Scale bar represents 5 mm. Grey pattern indicates broken areas. Abbreviations: co, condyle; ct, cotyle; hk, haemal keel; nc, neural canal, ns, neural spine; pcf, paracotylirr foramen; pos, postzygapophysis; pre, preaygapophysis; paf, parazygantral foramen; sn, synapoptiysis; zf, zygosphene; at, aygantrum.

33; Albino, 1986), including very small verle- Description. Only an incomplete vertebra brae each possessing a narrow centrum, shal- could be assigned tentatively to A. argenlinus low haemal keel, and low and thin neural spine (Fig. 5B1. This specimen bas only the centrnm (Albino, 1986). 'She zygantrurn is deep, with the and part of the left portion of thc neural arch dorsal edge sligilbly convex; this structure is preserved. The specimen li.om Bajo de SantaRosa not preserved in the holotype specimen. shares with the holotype of A. argenlinus (Halo- Comments. Up to now, this smallest species type MACN-PV RN 27; Albino, 1986) a similar of madtsoiid was recognized in the Los Alamitos morphology of the vertebral centrum, including Formation (Albino, 1986,19871, and in the Early a narrow and not very triangular in shape, with Eocene of Australia (Sca~llon,1993). The new a thick haemal keel separating deep lateral de- record in the Bajo de Santa Rosa locality expands pressions. This material is slightly smaller than the temporal and geographic distribution of this the holotype ofii. argentinus (MACN-PVKN 33). species during the Cretaceous. Comments. Alnrnitophis (Albino, 1986) is widely documented in the Los Alamitos, Allen, Madtsoiidae Hoffstetter, 1961 and La Colonia formations, as well as in the Early Alamitophis argentinus Albino, 1986 Eocene ofAustralia (Albino, 1994,2000;Scanlon, (Fig. 5B) 1993). If the taxonomic identifications of these records (only based on vertebral isolated re- Referred material. MACN-PV RN 1053: in- mains) are correct, this species has a broad tem- complete trunk vertebra. poral and geographic distribution in Gondwana. 272 Xeuista del Mcdseo Argentcno dr Ciencias Naturales, rr, s. 6 (21, 2004

As a preliniinar c~~mmcnt,Alamitophis seems lo deep, connecting both depressions by a shallow be the predominat snake in the Los Alamitos, transversal groove. Ttie area of the parazygantral Allen, and La Colonia forrnations. foramina and ttie postzygapophyses has been bm- ken off. ?'he condyle is oval shaped and faces Madtsoiidae Hof'fstettcr, 1961 poslero-dorsally. Cen. et sp. indet. This specirncn is larger than Ala~nitopizis (Fig. 5Cl argeiitinus and A. elongatus (Albirio, 1986, 1987, 1994) and differs from these two species in hav- liefirred Malerial. MACN-PV RN 1051, ing the vertebral centrum wide and stlort, shal- MACN-PV RN 1052 (Fig. 50, MACN-PV RN low dcpressioiis on both sides ofttie haemal keel, 1054: isolated trunk vcri.ebrae. shallow zygaiitrum with a transversal groove Ilescription. MACN-PV RN 1052 (Fig, 5C) is connecting botli, arid a thicker neural arcli. This the must complete vertebra Srom Bajo de Santa taxon from Kajo de Santa Rosa differs from Rosa that is referred to this l'dmily This veriehra Rionegrophis madtsoioides, the iargest rnadtsoiid has a parazygantral foramen wtiich is a unique snake from Los Alaniitos (Albino, 1986, 19871, vertebral synapomorphy of Madtsoiidae (Rage, in l~avinga narrow arid long centrum, a very low 1998). This specimen is a little larger than and wide zigospiiene, only one large paracotyiilr Patngoniophis par-ous and smaller tliari ihramen, and a well developed hacrnal keel. This Alainitophis argentinus. The vertebra is high arid possible madtsoiid differs froni Di~zilysia short. The haemal keel it* thin and limited later- patafionica (Woodward, 1901; Rage & Albino, ally by deep depressions. 'The neural spine is bro- 1989) in liaving the zygosphene transversely ken off on its posterior part. The zygailtrum is kirge and low, and a slender neural arch. In addi- high and deep with the dorsal border slightly con- tion, tliis specimen differs from Roidae snakes cave. The association of t,hese mentioned Seaiures in the proportion of the centrum and in the lack in the vertebra from Bajo de Santa Rosa differs of prezygapophysial processes. significantly from i'atagoniophis and Alamitophis Cornmetits. The specimen here described rep- making it difficult iu assibm it to genus level. resents the largest snake recovered From the Bajo M-4CN-PV RN 1051 (noi figured) corresponds de Santn Rosa locality The familiar status of this to a caudal vertebra due to the presence ofa pair taxon is doubtful due to the lack of the of pcdiceis for ttie cl~evronsnear the posterior postzygapophyses and part ofthe xygantrurn where end of the centrum, arid long narrow transverse the parazygantral foramen should be located. The processes ar~toro-laterallyprojected. combirialion of these features mentioned in this specimen could indicate the presence of a new ?Madtsoiidae Hofi'stetter, 1961 taxon, hut new findirigs are required iii order to Gerz. el sp, indet. support this statement. In addition to this speci- (Fig. 6) inen, uripublished vertebrae fmrn the 1,os Akamitos Formation could be assigned to the same taxon. Ruferred Mc~tei-id.MACN-PV RN 1059: al- Thesesueciniens are: WCN-PV RN 201. MACK niost complete trunk vertebra. PV RN 519, and MACN-PV RN 220. Description. MACN-PV RN 1059 (Fig. 6) coil- Commenls of lZioiiegraphis ~nadtsoioides.An sists of a trunk vertebra lacking both undescribed trunk vertebra (MACN-PV RN %261 postzygapopliyses, the anteriormost part of the of Rionegrophis n~adtsoioidesfrom the Los prezygapophyses, and the postero-dorsal portion of Alainitos Formation provides new information the neural spine. Ttie vertebra is lligl~and wide. about the taxonomic affinities of this species. N- The dorsal edge of the neural spine, alt.hongl, in- bino (1986, 1987) tentatively included this taxon complete, seems to be straight. The zygosphene is in the Madlsoiinae subfirriiiy b

Fig. 6. lMadtsoiidae MACN-PV RN 1949, trunk vertebra in dorsal (A), ventral (B1, anterior (C1, postcrior (U) and lateral (E) views. Scale bar represents 5 mm. Grey pattern indicates broken areas. Abbreviations as in Fig. 5.

DINOSAURS Ktirzanov & Ba~inikov,1983), and Europe (e.g., Lydekker, 1887; Le Locuff, 1993, 1995; Sanz et SAUlZOPODS a!., 1999). In recent ycnrs, the phylogenctic relationships Titanosaur sauropods are widespread in most ortitanosaurian sauropods have been reviewed by of continental Cretaceous beds of the world, but different authors, and the general consensus is arc more abundant. and diverse in Gondwana, that the titanosanrid Saltasaurinae appaars to be such as in South An~erica(e.g., Lydekker, 1893; one of the most derived groups from this lineage Huene, 1929; Bonaparte & Gasparini, 1978; (e.g.,Salgadoet al., 1997a; Upchurch, 1995,1998; Bonaparte & Powell, 1980; Powell, 1986, 2003; Wilson, 2002). Calvo & Bonaparte, 1991; Boiiaparte & Corid, At the prcsent, the tiianosanrid sauropods 1993; Salgado, 1996; Kellner & Aaevedo, 19991, reported from the Allen Formation are Africa (Deperet, 1896; Taquet, 1976; :lacobs et Aeolosuurus sp. (Salgado & Coria, 1993) and al., 1993; Curry Rogers & Forster, 2001; Smith Rocasaurus rnuniozi (Salgado & Azpilicueta, et a!., 20011, and India (e.g., Lydekker, 1877, 2000). Originally,Neuquensaurus australis (e.g., 1879,1887;Jain & Bandyopadhyay, 1997). Out- Lydekker, 1.893;Powell, 2003), Luplatasailrus (= side Gondwana, titanosaurs have been found in ,jaraukanicz~s (Iluene, 1929; North America (e.g., Gilmore, 1922, 1946;Llicas Powell, 2003; Wilson & Upchurch, 20031, and & Hunt, 19891, Asia (e.g., HoCfet, 1942; Pel!egri~~isa~~ri~spowelli isalgado, 1996) were Nowinski, 1971; Borsuk-Byalinicka, 1977; considered as corning from the Allcri Formation, 274 Revista del Museo Argenlino de Ciencias Nalurales, n. s. G /2j, 2004 but recent geological studies consider that these fragment of metacarpal, both femora, both tibiae, species were collected from the Rio Colorado left fibula, left calcaneous, left metatarsal I, and Subgroup (Heredia & Salgado, 1999). some fragmentary elements. A new small saltasaurine titanosaurid, Referred Material. MACN-PVRN 1061: com- Donatitan reigi gen. et sp. noo., based or1 two in- plete braincase, incomplete anterior cervical ver- complete specimens is described and compared tebra, left radius, left ulna, left femur, left tibia, here. These two specinlens were unearthed to- calcaneous, metatarsal 111, a few incomplete chev- gether from the same site at the Bajo de Santa rons, and some fragmentary indeterminate ele- Rosa locality ments. I,ocalit,y and lzorison. Both specimens were Dinosaurid Owen, 1842 collected in the Bajo de Santa Rosa locality. Rio Saurisckiia Seelcy, 1888 Negro Province, Argentina (Fig. 1); Allen For- Sauropoda Marsh, 1878 mation, Malargiie Group, Campanian-Maas- Titanosanria Bonaparte and Coria, 1993 trichtian (Uliana & Dellap6, 19811, Late Creta- Titanossuridae Lydekker, 1893 (sensu Salgado, ceous. 2003) Saltasaurinae Powe!l, 1986 (sensu Sereno, Description and Comparisons 1998) The holotype (MACN-PV RN 821) and the Bonatitan Martinelli & Forasiepigen, nou. referred specimen (MACN-PV RN 1061) were (Figs. 7-17) unearthed in the same paleontological site. The remains were disarticulated and the bones of each Type and only known species. Bonatitan reigi individual were mixed. The specimens were seg- sp. nou. regated on the basis of their reiaLive sizes. Diagnosis. Small-sized titanosaurid Salta- MACN-PV RN 821 is selected as holotype because saurinae characteriaed by the following associa- it is more conlpiete and the elements preserved tion of characters: 1) longitudinal groove located are rnore diagnostic than the other specimen. The on the suture between parietais thtdt continues estimatioa of the body size (mainly based on com- posteriorly over the supraoccipital to the fora- parisons of the length between the femora and men magnun; 2) basisphenoid tubera long and tibiae) suggest that the holotype specimen narrow (more than twice long as wide); 3) dorsal (MACN-PV RN 821) is approximateiy 20% larger to middle caudal vertebrae witb deep oval to cir- than MACN-PV RN 1061. The description arid cular pits on both sides of the prespinai lamina; comparinons are based on both specimens. The 4) anterior caudal vertebra with spino- measurements of the postcranial bones are given postzygapophysial and spino-prezygapoptiysiai in the appendix. laminae; 5)neural arch of anterior caudals witb deep interaygapophysial fossae with numerous Braincasc pits; 6) anterior caudal vertebra with an acces- Dermal bones and Chondrocranium. Two well sory sub-horizontal larnina extending from the preserved braincases are avaiiahie. Most of the antero-ventral portion of the postzygapophysis chondrocraniuln is preserved in both specimens to the mid-portion of the spino-prezygapophysial of Bajo de Santa Rosa, and it is formed by su- lamina; finally, 7) anterior caudal vertebra with praoccipital, exoccipital, basioccipital, basisphe- aprominent axial crest on the ventral surface of noid, parasphenoid, orbitosphenoid, lateros- the cemtrum. phenoid, prootic, and opisthotic bones. The only Elyrnology. The genus is named in honor of dermal bones preserved are the frontals and pa- Dr. Jos6 E Borlaparte, due to his immense con- rietal~.The sutiires are clearer in MACN-PV RN tribution to the knowledge of Mesozoic verte- 1061 than in MACN-PV RN 821 perhaps in cor- brates of South America. relation with the smaller size and younger age of the former specimen. For descriptive purposes, Bonatitan reigi Marlinelli & Forasiepi sp. nou. the articular surface of the occipital condyle is posteriorly oriented as it occurs in Rapelosourus Diagnosis. As for the genus. krausei, which has one of the better-preserved Etymology. The species is named in honor to titanosaur skull (Curry Rogers & Forster, 2001, Dr. Osvaldo Reig for his contribution to South 2004). American paleontology The frontals (Fig. 7) are antero-posteriorly Nolotype. MACN-PV RN 821: complete hrain- short; they are not fuscd in the sagittal plane as case, middle dorsal vertebra, anterior caudal ver- observed in most sauropods (e.g., titanosauriforrns tebra, middle caudal neural arch, left humerus, and diplodocids; IInene, 1929; Berman & Mcln- Nlarti~zelli& Forasiepi: Late Cretaceous vertebrates from Rio Negro, Arger~lina 275

Fig. 7. Bonatitan reigi gen et sp. nou. II6lotype MACN-PV RN 821, st,ereopliotugraphs with accompanying line drawing of the basicranisrm in dorsal (A), occipital (B) and lateral (C) views. Scale bar represents 50 mm. Abbreviations: Bs, basisphenoid; Bo, basioccipitai; bst, basisphenoid tuber; btp, basipterygoid process; ca, crista nntotica; caf, carotid foramen; co, occipikal condyle; cpr, cresta prootica; Eo, exoccipitai; fm, foramen magnum; fo, fenestra oval; Fr, Srontal; jv, jugular vein foramen; Ls, iaterosphenoid; mf, ~netoticfissure; Os, orbitosphenoid; F: parietal; pop, paraoccipital process; Ps, parasphenoid; Soc, supraoccipital; spfr, surfaces ror the prefrontal; spo, surliaces for the postorbital; stf, supratemporal fossa; I-VIII arid XII, cranial nerves foramina.

tosh, 1978); in coni:rast, they are fused posteri- the frontals have two concave surfaces divided orly with the parietals. The external surface of by a sharp and almost transversal crest. The larg- the ikontals faces dorsally and forms the ante- est vcntral surface supports most of the rior border of the supratemporal fenestra as in orhithosphenoid and laterosphenoid, and forms other titanosaurids ie.g., Antactosaurus, the posterior wall of the orbital cavity; the small Rapetosaurus and Saltasaurus; Huene, 1929; dorso-medial surface forms the posterior wall of Curry Rogers & Forster, 2001, 2004; Powell, the olfactory tract and supports the region of the 2003). On the anterior region of the suture be- orhitosphenoids where the olfactory bulbs lie. tween the frontals there is an inverted au~>Between the dorsal contact of the frontal and shaped tuberosity. On the lateral edge of the fron- orbitosphenoid there is a transversal groove for tal there are two articular surfaces: an anterior the anterior cerebral artery (Berman & McIn- one for the articulation with the prefrontal and tosh, 1.978). a smaller postero-lateral one for the articulation The parietals (Fig. 7) contribute to the roof with the postorbital (the prefrontals and of the skull; they are mainly exposed in dorsal postorbitals are not preserved). On the inner side, view These hones are relatively wider than in 276 Reuzsta del Museo Argentzno de Czenczas Araturales, n. s. 6 12/, 2004

Ar~tarctosaurw,hut similar to Rapelosaurus. The The hasisphenoid forms mainly the parietals are shorter antero-posteriorly than the basispterygoid processes and a portion of the frontals, and slightly concave. The anterior edge crista prootica; the sutures among surrounding of the parietal forms a crest that deliinits the bones are not observable. The basispterygoid posterior border of the supraternporal fenestra. processes of the basisphenoid are long, antero- The contact of the parietal with the supraoccipi- ventrally projected, slender, and less divergent tal and exoccipital is not observable. In the sag- than in Antarctosaurus (in whicti an angle of al- ittal plane, where hotti parietals contact, there most 90 degreos is formed; I-Iucne, 1929); hut . . I?.. I.. , !I!!. Ill!:.. I : : . .:. .,. /:.;..I >.!.,,. . 1:: n,xm I. ,vt.~.I:. , 7 !I>I..\C,.:I,.I 11 'i'!~.: .:!OLY,,.~I ";. ' ll\,~.r:*\" !:.:* .,I.,? I 'L!t,:'...:.:~.!t~.~:,,i(l. .,,:.I for attactlmerit of the axial musculature, defines (Figs. 70, C1 are elongated and narrow, unfused a longitudinal groove that extends from the pa- to each other, and delimit the lower surfaces of rietal to the foramen magnum. The groovc over the pituitary fossa. The basisphenoid tuhera of the parietals is only observable in Bonatilan. Bonatitan differ from Antarctosaurus and The parietal fontanelle and post-parietal fon- Rapelasaurus which have dorso-ventrally shorter tanelle are both absent in Bonatitan as in all and transversely wider tubera (Huene, 1929; known titanosaurs. These openings are only de- Curry Rogers & Forster, 2004). In Saltasaurus, veloped in llicraeosaurus and Amargasaurus the tuhera are fused (Powell, 1992, 2003). (Janensch, 1935-36; Salgado & Calvo, 1992). The parasphenoid is broken in both speci- The supraoccipital (Fig. 7) is fused laterally to mens, hut according to the preserved base ofthe

,A " ,, rarnen magnum. On the posterior surface the su- The orbitosphenoids (Figs. 7C, 8) face praoccipital bears a longitudinal groovc that anterolatcraly and are pierced by several foramina reaches the foramen magnum (see also above). for the exit of the cranial nerves (see below; Fig. This groove is also present in Rapelosaurus (Curry 8). In anterior view, the orhitosphenoids meet cactl Rogers & Forster, 2004) but apparently it does not other; posteriorly they are partially fused with the extend anteriorly on the parietal as in Bonatilan. latcrosphenoid and dorsally they are in contact In Anctartosaurus (MACN-PV 6804) the supraoc- with the frontals. cipital forms a distintive process but a longitudi- Sutures of the laterosphenoids (Figs. 7C, 8) nal groove is riot evident (Huene, 1929; contra with the parasphenoid, hasisphenoid, and otic Curry Rogers & Forster, 2004). The dorsal edge of bones are not discernible. The laterosphenoids the foramen magnum in MACN-PV RN 821 is project laterally contacting dorsally with the rnore concave than in MACN-PV RN 1061. frontals; contributinganterolaterally to the crista The supratemporal Senestra (Fig. 7) is ex antotica. Above the crista antotica, near the fron- tremely short antero-posteriorly and very wide tal, there is a depression with a small foramen transversely, the anterior edge is convex while the for the mesencephalic vein (Berman & McIntosh, posterior one is slightly concave, and opons on the 1978). dorsal surface of the skull. In Camarasaurus There are no clear sutures hetween the (Madsen et al., 19951, Brachiosaurus (Janensch, exoccipital and the surrounding hones of the skull 1935-36, 1950), Diplodocus (Upchurch, 19991, (Fig. 7). The paraoccipital processes are promi- Rebbachisaurus (Calvo & Salgado, 1995), and nent, ventrally projected, and hear a roughly lat- dicraeosaurids (Janensch, 1935-36; Salgado & eral surEace for the articulation with the squa- Calvo, 1992) the frontals are excluded fkom the mosal as in Saltasaurus. These processes are situ- anterior edge of the supratemporal fenestra. In ated at the same level of the occipital condyles Nemegtosaurus (Nowinski, 1971) the participation as in other titanosaurids (e.g., Antactosaurus and ofthe frontal in the border of tile supratemporal Rapetosaurus),with the exception of Saltasaurus fenestra is very reduced. where they occupy alower position (i.e., they are Thc hasioccipital (Fig. 7) forms the occipital longer and more ventro-anteriorly projectod). condyle, which is prominent and almost spheri- The paraoccipital processes are <.-shaped,a cal. We follow tile interpretation ofRapetosaurus condition similar to that found in Saltasaurus, (Curry Roger & Forster, 2001,2004) in which the Antarctosaurus, and Rapetosaurus. occipital condyle is posteriorly projected rather The prootic and opisthotic bones are strongly than postero-ventrally as in Brachiosaurus fused. Tile crista prootica is thin and dorsally (Janensch, 1935-36, 19501, or ventrally as in delirnits the niiddle ear cavity, which is deep and dicraeosaurids and diplodocids (Salgado & Calvo, postero-ventrally faced. The fenestra oval, which 1992; Berman & McIntosh, 1978). accommodates the footplate of the stapes, is oval- Martinelli & Forasiepi: Laie Cretaceous uerlebrates from IZiu Negro, Argentina 277

bitosphenoid and laterosphenoid, and laterally faced. The anterior rim is straight with a well- defined border, while the posterior border is slightly concave. In Antarctosaurus (IIuene, 1929) and Saltasaurus (Powell, 2003) this fora- men is oval in shape. Ttie lrochlear foramen (CN IV) is a very small opening, located on tlie suture between the or- hitosphc~ioidand laterosphenoid, ahove the ocu- iomotor foramen. The orbitosphenoid forms the anterior riru whereas the laterosphenoid forms Viii the posterior one. fo The trigeminal foramen (CN V,,) is larger than the optic foramen, as in Sultsnurus, Antarctosaurus (Huene, 1929; Powell, 1986), and Rapetosaurus (Curry Rogers & Forster, 2004). The trigemindl foramen is located on the suture

; betweell the laterosphenoid and 1he prootic, postero-ventral to the oculomotor foramen. The sharp crista antotica delimils this forairieil antero-dorsally, wlrereas the crista prootica forms Fig. 8. Banalitan reigi gen et sp. ~zov.Holotypc the postero-ventral rim of this foramen. The MACN-PV RN 821, line drawing of the antcro-ventral border of the trigerninal forarrien basicranium in vcntro-lateral view with the has a groove for the maxillary branch of the condyle ventrally oriented. The righk preserved trigcminal nerve (CN V,) that reaches t,lic basipterygoid process is not fikwrcd. Scale bar basipterygoid process of the basisphenoid. In represents 50 mm. Abbreviations as in Fig. 7 Quaesitosaurus (Kurzanov & Bannikov, 1983), Camarasaurus (White, 1958), Diplodoci~s (Berman & McIntosh, 1978), Rebbachisai~rus shaped and iocated in the center of the middle (Calvo & Salgado, 19951, and dicracosaurids ear cavity. (:Jtanensch, 1935-36; Salgado & Calvo, 1992) the li'oraminae. Description of the braincase fo- trigemil~alforamen is snialler in relation to tile ramina (Figs 7C, 8) is mainly based on Lhe fol- remaining crariial nerve foramina. lowingstudies: White, 1958; Berman & Mclntosh, The ahduceris foramen (CN VI) is sinall and 1978; Saigadu & Calvu, 1992; Powell, 1992,2003; ioca~edahove and anterioriy lo the carotid fora- and Galtun, 1985, 1989. men. Based on other sauropods this foramen The exit for cranial nerve (CN) I (olfactory should he located at the level of the suture be- tract) is relatively large and faces antero-dorsally tween the orbitasphenoid and paraspherioid (but between the orbitosphenoid and Gontals as in this suture is not clearly discernable in most sauropod tam. Bunatitan). The optic foramen (CN 11) pierces the orbito- The faciai foramen (CN VII) is small, eye sphenoid; it is an oval-shaped opening, facing shaped, and anteriorly faced. It is surrouiided anterolateraly, and larger than the fbramen for dorsally by the aiispiicnoid and ventrally by the the oculomotor nerve (CN 111); this morphology prootic. This opening is located on tho crista is similar to Saltasaurus (Powell, 1.9861, prootica below the foramen for the CN V Quaesitosnurus (Kurzanov & Bannikov, 1983), The acoustic foramen (CN VIII) is circular- and Rapetosai~rus(Curry Rogers & Forster, shaped, siriallcr than the facial forameii, and 2004). In Camarasauri~s (White, 1958), placed in the middle ear cavity dorsal to the fcries- Diplodocus (Berman & McIntosh, 1978), tra ovalis. Rebbaclzisaurus (Calvo & Salgado, 19951, and The glossophilryngeal (CN 1x1, vagus (CN X), Amargasaurus (Salgado & Calvo, 1992) the op- and accessory (CN XI) rierves, and the jugular tic and oculomotor foramina are considerably vein pass through the metotic fissure (De Beer; smaller and almost equal in size. In the speci- 1937) on the posterior wall ofthe middle ear cav- men MACN-PV RN 1061 the optic foramen is ity This fissure is the largest opening of the lat- relatively smaller than in MACN-PV RN 821. eral wall of the braincase, located postero-ven- The oculomotor foramen (CN 111) is eye- trally to the fenestra ovalis; both openings are shaped, situated on the suture hetween the or- separated by a thin bony wall. 278 Reuista del Museo Argentina de Ciencias Nutt~mles,n. s. 6 /2j, 2004

and very antero-posteriorly elongated, even more so than Saltasaurus (Powell, 1986, 2003; Bonaparte; 1999) and Isisaurt~s(Jain & Randyopadhyay, 1997; Wilsori & Upchurch, 2003). Ttic pleurococls, placed above the poste- rior edge of the parapopkiyses, are oval and deeper than in Sallasaurus. The pleurocoels are divided by an oblique septum, also present in Saltasaurus (Powell; 1986,2003). The parapophyses are thin and iatero-ventrally oriented. Due to the relative sniall size, this centrurri is tentatively assigned to the srnallcst specimen (MACN-PV RN 1061). Dorsal vertebra. An almost coinplete dorsal verl.cbra (Figs. 10, 11) was recovered and based on the size it is assigned to the holotype. The left postzygapophysis and the distal portion of the neural spine are preserved and hroken from the rest oi'the t~euralarch (Fig. 12). We interpret this eleincnt as a iniddie dorsal vertebra due to the possession of a deep postparadiapophyseal fossa (sms:i Ronaparte, 1999; fossa placed posteriorly to the anterior centroparapophyseal lamina of Wilson, 1999); and because t.kie g~arapophysc.%$are high and anterior to the diapophyses. The

larger antero-posteriorly than wide. The pleurocoei is deep and eye-like shaped with well delimited edges as in Ne~~quensaurus(Powell, 2003); in Saltasaurus and isisauras (Jain & Bandyopadhyay, 1997; Wilson & Upchurch, 2003) tile anterior and veritral edges of the pleurocoel Fig. 9. Bonalitan reigi gen et sp, noo. MACN-PV slope gradually. Tkie neural arch and the centrurn RN 1061, photographs of the anterior cervical centruin in iateral (A) and ventral (B) views, witti are separated; both elements tiave cancellous os- seous tissue. The posterior ccntrodiapophyseal accoiripanying line drawing in lateral view (12). larnina (pcdl) (infradiapophyseal lamina sensu Scale bar represents 50 mm. Grey pati:ern Bonaparte, 1999) is thin and vertically reaches indicates broken areas. Abbreviations: pl, pleurocel. tfic centrum at the posterior region as in the middle dorsal vertebrae of Saitasaz~rusand 1Veuquensaur:is. The thin anterior centropara- pophyseal lamina (acpl) runs almost parallel to The hypoglossal foramen (CN XII) opens in the posterior centrodiapophyseal lamina (pcdl). the exoccipital, posterior to the base of the The articular surface of the parapophysis faces paraoccipital process, and outside of the middle laterally and is nearer to the preaygapophysis ear cavity. tkian to the diapophysis. The prezygapophyses are The carotid foramen is fully enclosed in the located at the sarne level as the parapophysis, hilt basispterygid process. This opening is smaller face dorso-medially The centropre~ygapophyseal than that of Saltasaurus and Antactosatlrus. larnina is ahseiit as in Neuquen,saurus (Powell, Near the carotid fbramen a small indeterminated 1986, 2003) and Rocasauras (Salgado & foramen is present. Aapilicueta, 2000). The postparadiapophyseal fossa (pparf? is deep and constitutes the most Postcranial skeleton remarkable feature in lateral view The diapophy- Cervical iierlebra. The cervical vertebra (Fig ses are slender and are directed latero-dorsally. 9) consists of an anterior centrurri strongly The postzygodiapophyseal lamina (podl) (diapo- opisthocoelous with the parapophyses located on postzygapophyseal lamina sensu Ronaparte, the anterior half (the neural arch is not pre- 1999) is slender and hears on its dorsal surface served). The centrum is almost as high as wide some oval depressions arid pits, a unique feature *tine112 & Forasiepi: Late Cretaceous vertebrates from Rio hTegro,Argentina 279

Fig. 10. Bonatilan reigi gen el sp. nov. EIolotype MACN-PV RN 821, stereophotographs with accompanying line drawing of middle dorsal vertebra in anterior view. Scale bar represents 50 mm. Abbreviations: dia, diapophysis; nc, neural canal; pdr, parapophysis; prel, prespinal lamina; pr, preaygapophysis.

Fig. 11. Bonaiilan, reigi pen et sp, nou. Holotype MACN-PV RN ml, stereophotographs with accompanyiilg line drawing of middle dorsal vertebra in lateral view Scale bar represents 50 mm. Grey pattern indicates broken areas. Abbreviations: acpl, anterior centroparapophysial lamina; dia, diapopllysis; par, parapophysis; pcdl, posterior centrodiapophysial lamina; pl, pleuroce!; podl, postzygodiapophysial lamina; pparf, postparapophysial fossa.

among titanosaurs. Tile infrapostzygapophysial sprl+prsl sensu Wilson, 1999) is thin (however lamina (tpol) is thin and incompletely preserved. it is badly preserved in the fragment of the neu- The infrapostzygapophysial fossa is deep and ral spine). Thc undivided neural spine has its faces posterolateraliy In the basal portion of the right half portion broken off (Fig. 12); it seems neural arch the prespinal lamina (prel) to he transversely wide anddorso-ventrally short. (spinoprezygapophyseai plus prespinal laminae, In anterior view, the prespiilai lainiria separates Revista del Museo Argentino de Ciencias Naturales, n, s. 6 (2), 2004

Fig. 12. Bonatila,l I-eigigen rt sp, nov. kIolotype MACN-PV RN 821, photographs or the neural spine of the middle dorsal vertebra in anterior (A) and posterior (B! views. Scale bar represents 50 mm.

two deep lateraldepressions (Fig. 12A).This por- latel.;il sides. The spinoprexygapophyseai (sprl) tion of the rieural arch preserves the left and the spinopostzygapophyseal (sposl) iarniiiae postzygapophysis, viliich is extremely hollow as are well-defined, and between each there is a deep shown in fi~ire12, and its articular surface is and large interaygapophyseal fossa divided by a latero-ventrally oriented. sub-horizontal accessory lamina (acl!. The dor- Caiidal r;ertebr.ae.The almost coinplcte ante- sal interaygapophyseal fossa extends dorsally, rior caudal vertebra (Figs. 13-15) and the rielirai above the level of the postzygapophysis. The ven- arch of a middle caudal vertebra (Fig. 16) are tral intcrzygapophyseal rossa is smallar and shal- preserved; they are considered to belong to the lower, extending ventrally to the level of the largest specimen (MACN-PV RN 821). prezygapophysis. Inside both Sossae there are The anterior caudal vertebra (Figs. 3 3-15) is subcircular pits similar to those present lateral strorigly procoelous, llavi~igball arid socket ar- t,o the prespi~iallamina. ticuiar facets. The centrum is wide, short, high, The prezygapophyses are anteriorly directed, and bears a prominent axial ventral crest. This and the articular surfaces Sace dorso-mediaily. The reatlire is absent in the currently kiiown postxygapophyscs are located at the level of the titaiiosaurs and is corisidered an autaporriorphy posterior edge orthe neural spine. The postspiilal of ijonatitan. Saltasaiiri~s,Nei~ijuensaurus, and lamina ipostl! (medial spinnpostaygapoph-jseai Iiocosaurus have the anterior caudal vertebrae plus postspinal laminae, med. spol i-posl, sensu dorso-ventrally col~ipressed(Powell, 1986, 2003; Wilson, 1999) is wider than the prespinal one. Hucne, 1929; Salgado & Azpilicueta, 2000) bear- The middle caudal neural arch (Fig. 16) is not ing an axial ventral depression, In Rocusaurzis cornplot,ely fused to the vertebral centrum. Tlie this depression is relatively deeper with an axial neural spine is short, rohost but extremely hollow, septun~. and steeply inclined backwards. The anterodorsal On the lateral aspect of the anterior caudal corner ofthe spirle is at the sanie level of the poste- vertebra, above the axial crest, the lat,cral sur- rior edge of the postzygaphopliysis as in face of the ccntriim is dorso-ventrally convex. Sollusauri~s,Nei~q~~e~~,sauriis,and Rocasauriw. (Fig. Oriiy the bases of both diapophyses an. preserved. 17).This feature was considcred a synapomorphy The circular shaped neural canal is longer than of the Saltasaurinae (Salgado et ol, 1997a). The those preserved in the caudal vertebrae of prespirial lamina divides two deep depressions, as Salta,saurus. Tlie neural spine is low, similar to occurs in the neural arch described above. Inside Sa1tasai~1.u~.'She prespiiial lamina (prel! is thin, these depressioiis there are deep pits decreasing bearing well-detincd oval pits on both concave posteriorly insize. Asimilar feature, but not as de- Marlinelli & Forasiepi: Late Cretaceous vertebrates from Rio ,Negro, Argentina 281

Fig. 13. Bonatitan reigi gem et sp. nou. Hoiotype MACN-PV RN 821, stcreophotograpiis with accompanying linc drawing of tile anterior caudal vertebra in anterior view. Scale bar represents 50 mm. Grey pattern indicates broken areas. Abbreviations: nc, neural canal; prei, prespinal lamina; pr: prezygapophysis; sprl, spinoprezygapophysid lamina.

vcr

Fig. 14. Bonatitaiz reigi gen et sp, nou. Holotype MACN-PV RN 821, stereophotographs with accompanying line drawing of the anterior caudal vertebra in lateral view. Scale bar represents 50 mm. Grey pattern indicates broken areas. Abbreviations: acl, accessory lamina; ns, neural spine; pos, postzygapophysis; postl, postspinal lamina; pr, prezygapophysis; sposl, spinopostzygapophysial lamina; sprl, spinoprezygapopliysial lamina; vcr, ventral crest. Reuista del Museo Arpentino de Ciencias Nnturales, 1%. s. 6 (2), 2004

Fig. 15. Bonutitan reigi gen et sp, now. Holotype MACN-PV RN 821, stereophotographs of the ante- rior caudal vertebra in posterior view. Scale bar represents 50 mm.

veloped as in this new species, is observed in the distal one. Both distal epicondyles are not well middle caudal vertc!brae of Neuquenwurus (Powell, developed. The humerus length relation with the 2003: Plate 58). The prezygapophyses are promi- fernur is approximately 0.8. nent, antero-dorsally directed with the articular Ulna. The left ulna (Fig. 18B) is cornpletely surfaces dorso-metiidly exposed. The postspinal preserved and belongs to the smaller specimen lamina is more prominent and robust than the (MACN-PVRN 1061).This element is moreslen- prespinal one. Between both postzygapophyses, der than in Neuquensaurus and Saltasaurus at the base of' the postspinal lamina, there is a (Huene, 1929; Powell, 1986, 1992, 2003). The deep fossa similar to Neuquensaurus (Powell, proximal end is rugose, slightly convex and sub- 2003). trianyuiar, with a concave proximal border of the Humerus. A complete left humerus (Fig. 18A) radial fossa (Fig. 18B). The olecranon process is was recovered and assigned to the halotype. The absent. Proximally, the antero-lateral surface of humerus is more slender than in Neuquensaurus the ulna is concave for the articulation with the and Saltasaurus (Huene, 192%Powell, 1986,1992, radius. The posterior surface of the shaft is al- 2003). The hnmeral head and deltopectord crest most plane and bears a ridge on its distal half arc poorly developed similar to Laplatasaurus that ends near the distal end. The distal surface (Huene, 1929), Lirainosau?-us(Sanz et al., 1999), is also rugose, rectangular in cross section, and and Rapetosaurus (Curry Rogers & Forster, transversely narrower than the proximal end of 2001); instead, Neuquensaurus and Saltasaurus the bone. have a more prominent head and robust Radius. A left radius is incompletely pre- deltopectoral crest. The shaft is narrow and the served and also belongs to the smaller specimen. proximal end is wider than the distal one. The The proximal end is broken on ttie antero-me- proximal end is slightly rotated in relation to the dial edge. The shaft is oval in cross section, and Marlinelli & I?orusiepi: Late Crelaceous vertebrates fiom Rio Negro, Argemlina 283

Fig. 16. Bonatitan reigi gen et sp. nou. Holoiype MACN-PV RN 821, pliotographs of the middle caudal neural arch in left lateral (A), dorsal (B), and right lateral (C)views, and accompanying line drawing in lateral (D) and dorsal (E) views. Scale bar represents 50 mm. Abbreviations: ns, neural spine; pos, postzygapophysis; postl, postspinal lamina; prel, prespinal lamina; pr, prezygapophysis.

the surface for ulna articulation is concave. Most ral shaft; there is an intercondylar notch betwean of the distal end is missing. ahern. Femur. The holotypo has preserved both Tibia. Both tibiae (Fig. 18D) were recovered for femora (Fig. lac),and MACN-PV RN 1061 only the holotpe, while only theleibone for the referred the left element. The femur is antero-posterioly material (Fig. 18E).The tibia is nearly 12%,smaller flat, hearing on the latero-proximal edge a slightly than the femur The proximal end is antero-poste- marked bulge, as in other Titanosauriformes riorly narrower than in Neuquensau,sus and (Salgadoet al., 199%; Wilson & Sereno, 1998). The Sallasaurus (Huene, 1929; Powell, 1992,2003), and femoral head is rather medial than dorso-medi- quite similar toLaplatasaurus (Huene, 1929). The

ally projected. The medial border or the femoral cnemial crest is thin and poorly- ~ developed, differ- head is more curved in ./LACN-PV RN 1.061(as in ingfrorn Neuquensaurus and Sulta,saurus in which Saltasauras and Neuouensaurus: Powell. 1986. it is robust and nrominent. The distal end is trans- 2003) than in the hdlotype. The greater tro: versely broad as in other titanosaurs (Salgado et chanter is located at the level of the head, and al., 1997a). The main axis of the proximal surface the fourth trochanter is not evident. The tibia1 has a relation of aproxinlately 90' with the main condyle is niore prominent and more distally de- axis of the distal surface, similar to Sultasaurus veloped than the Fibular one as it is observed in and Neuquensaurus (Powell, 1992; Sanz el al., Neuquensaurus and Saltasat~rus,but different 1999). from Rocasaurus that has similar sized condyles Fibula. Only the complete left fibula (Fig. (Salgado & Aspiiicueta, 2000). Both condyles are 18F) assigned to the holotype is preserved. This expanded onto the anterior surface of the femo- is a relatively straight and slender bone with a 284 Revista del Museo Argentino dr Ciencias Nuturales, n. s. 6 (a,2004

the clade that includes the more recent common ancestor of Neuyuensaurus australis and Saltasaun~sloriculus, and all its descendants (Salgado et al., 19978). This group was originally diagnosed hy Salgado el al. (1997a) based on the following derived features: a) short cervical prezygapophyses near the level of the diapophy- ses; b) depressed anterior caudal cerltra, with dorsovei~trallycorivex lateral faces; and c) antero- dorsal edge of the neural spine located posteri- orly with respect to the anterior root of the middle-caudal postzygapophyses. In addition, the presence of cancellous osseous tissue in presac- ral and anterior caudal vertebrae was considered Fig. 17. Comparison of rniddle caudal vertebra another synapornorphy of Saltasaurinae (Powell, aniong Titanosauridae in lateral view. A. 1986). Aeu1osaui.u~sp. (modified from Salgado & Coria, Curry Roger & Forster (2001) interpreted 1993); B. Alarnosai~ruccanjuariensis (modified Saltasaurinac as a more inclusive taxon, which from Gilmore, 1946); C, i"?euyuensaurus auslralis includes Alamosaurus, Titurlosat~i-us,Opistho- (modified Crank Salgado & Coria, 1993); D. coelicaudia, Neurjuensaorus, and Sallasaurus. Saltasaurus loricatus (iuodified froni Powell, These taxa were nested together due to the pres- 1992); E.Ilocasaur~zas mzcniozi (modified from ence of four unambiguous traits: biconvex first Salgado & Azpilicncta, 20003; F Bonatitan reigi caudal centrurn, deltopectoral crest reduced to a gen et sp. nou. Scale bar represents 50 mrn iow rounded crest, mar.ual digits 11 and I11 witil- out phalanges, and proximal breadth of the tibia more than twice its nlidshaft breadth (Curry Roger & Forster, 2001). Wilson (2002: 269) in- weak antero-lateral tuhcrosity located above the terprct.ed Saltasaurinae as composed by middle of the shaft. The proximal articular sur- Neuquensourus plus Saltasa~~rus,sharing four face is trian~qbar;in contrast, ,the distal one is uncquivocals features: cervical neural arch iaini- oval. This bone is slightly shorter than the tibia. nation well developed; spongy caudal hone tex- Metatarsal I. The left metatarpal I is assibned ture; posterior caudal centra dorso-ventrally flat- to the holotype specirneri. This bone is short and tened; and femoral distal condyles exposed on the robust (Fig. 18G). The proximal sureace is slightly anterior portion of the fen~oralshaft. This sub- convex and subrectangular with the posteronie- family together with Opist.hocoelicaudiinac, com- dial corner posteriorly projected. The posterior prise the family Saltasauridae proposed by surface of the shaft is coilcave and the anterior Sereno (I 998) in replacement of TiLanosauridae. one is almost straight. The shaft is transversely Later, in order to clarify the term Tita- narrow The distal surface is also rectangular with nosauridae, Salgado (2003) reviewed and estah- the lateral area distally projected. This metatar- lished a new taxonomic proposal for the higher- sal closely resembles that of A~euquensu.ori~staxa of Titanosauria. In his work, the family (Huene, 1929) andAeolosaurus sp. (Salgado et al., Titanosauridae was justificated as a valid name, 19971)), with the shsfa more slender than in instead ofsaltasauridae (see Salgado, 2003). Also, Ar~tur-ctosaurz~s(Huenn, 1929). Salgado (2003) redefined Saltasaurinae as all the Metatarsal 111. This metatarsal is smaller in cutitanosaurs closer to Soltasa~~rusthan to comparison to rnetatarsal I and it is assigned i.o Opisthocoelicaudia (following the interpretation the smallest specimen (MACN-PV RN 1061).The of Sereno, 1998; Wilson, 2002; Wilsori & proxirnal surface is triangular, antero-posteriorly ijpchurch, 2003). In addition, Saltasaurinae and elongated, and slightly convex. The distal sur- Opisthocoelicaudiinae (Sereno, 1998) are nested face is rectangular and transversely wide. The within the stem-based taxon Eutitanosauria (pro- narrower section of the shaft is located in the posed by Sanz et al., 1999). lower half of the hone. The anterior surface is Hitherto known, following the latter phylo- flat while the posterior one is strongly concave. genetic definitions of Saltasaurinae (sensu Sereno, 1998; Wilsoi~,2002; Salgado, 2003; Wil- Comments of Bonatitan reigi son & Upchurch, 2003), the members are The subfamily Saltasaur~nae,proposed hy Saltasaurus loricatus from the Campanian- Powell (1986), was pi~yiogeneticallydefincd as Maastrichtian of the El Rrete Formation (Salta Martinelli & Forasiepi: Late Cretaceous vertebrates from Rio Negro, Argentina 285

Fig. 18. Bonatitan rezgi gen et sp. nou. Rolotype MACN-PV RN 821, pilotographs of A. left hum crus in posterior view; B. left ulna in posterior and proximal views; C. left fernur in anterior view; D left tibia in lateral and medial views; E. left tibia in lateral vicw (juvenile specimen MACN-PV RN 1061); 'Icft fibula in lateral view; G. loft metatarsal I in lateral, medial and posterior views. Iicaie bar represents 50 mm. Figs. A, C-F are at the same scale. 286 Reuzsta del Museo Argentzno de Clenczas Naturales, n. s. 6 121, 2004

Province, Argentina; Bonaparte & Powell, 1980; bmic plan, common with other titanosaurids such Powell, 1986, 1992), Neuquensaurus australis as Laplntasaurus and Rapetosaurus. from the Coriiaciail-Santonian of the Bajo de la The presence of spinoprezygapophyseal and Carna Ebrnration (NeuouBn Province. Areentina: sainonostzveanoahvscai laminae in the anterior . . "U.." ~~ddeker,1893; ~uene:1929; ow ell, 19921, and caudal vertebra of Boualilan is a feature also re- 12ocasaurus mu~riozifrom the Campanian- ported in Mendozasaurus neguyelup (GonzBlez Maastrichtian of the Allen Formation (Ria Ne- Riga, 2003), Lirainosaurus aslibiae (Sanz et al., &TO Province, Argentina; Salgado & Azpilicueta, 19991, and Rapetosaurus krausei (Curry llogers 2000). & Forster, 2001). Furlhermore, the presence or Bonatitan reig7: shares the typical titano- an iriterzygapophysial fbssa in the anterior cau- sauriforrn feature of a lateral bulge in the fernur dal vortt?brae was recognized in Lirainosaurus (McIntosh, 1990; Salgado el al., 1997a); arid (Sam et al., 1999), Mendozasaurus (Gonzalez titanosaur fealures, including eye-shaped Iliga, 2003), and less dr!veloped in Malawisaurus pleurocoeis in dorsal vertebrae, posterior dorsal (Gornani et al., 1999). These characters tliat show vertebra with ventrally wide centrodiapophyseal a significant variation among spccics need to he and centroparapopbyseal laminae andprocoelous re-analiaed in order to understand their evoiu- anterior caudal centra (Calvo & Bonaparte, 1991; tionary transformation among titanosaurs. Bonaparte & Coria, 1993; Salgado et al., 1997a; Despite the large number of titanosaur spe- Wilson, 2002). cies discovered around the world, only few speci- Bonatitarb reigi is here considered as a new mens have preserved cranial elements. Skull hones Saltasaurinae because it exhibits the following are known in Antarctosaurus wichmannianus diagnostic features of the subfamily: 1) Antero- (Huene, 1929), Saltasaurus loricatus (Powell, dorsal edge of tile neural spine at the posterior 1986, 19921, Malawisaurus dizeyii (Jacobs et al., level of the nostzveanoahvses in the middle cau- 19931. Neme~tosa~~rusmoneolienisis (Nowinski. . "-.A,, " - dal neural arch (Fig. 16). Contrary, other non- 1971), Quaesitosaurus orientalis (Kurzanov & saltasauririe titanosaurids such as Aeolosaurus Bannikov, 1983), Iiapetosaurus krausei (Curry (Powell, 1987a; Salgado & Coria, 1993; Salgado Rogcrs & Forster, 2001, 20041, Lirainosaurus et al., 1997133 and Alamosaurus (Giimore, 1946) aslibiae (Sanz et al., 1999), and unnamed taxa have the neural spine dorsally or anteriorly pro- from India (Berman & Jain, 1982), Europa (Le jccted (Fig. 17). 2) Distal femoral condyles ante- Loeuffelal., 198% Weishampclet al., 19911, and riorly exposed. This feature was also recognized Argentina (Calvo et at., 1997a; Martinez, 1998; in Rapeto.suurus (Curry Rogers & Forster, 2001). Coria & Salgado, 1999). Controversial liypotlicses 3) Cancellous osseous tissue in the presacral and concernirig tht? skull morphology (a diplodocid or caudal vertebrae, mainly observed in the neural camarasaurid aspect), orientation and relation- arches. Other syriapornorphies of Saltasaurinae ship of the skull bones (McTntosh, 1990; Calvo, such as the presence of short cervical prezyga- 1994; Jacobs el al., 1993; Salgado & Calvo, 1997; pophyses and depressed proximal and middle cau- Upchurch, 1995, 1999) were partially clarified dal centra is unknown in the two available spcci- after the discovery of Rapetosaurus krausei rnens of Bouatitan. The only caudal centrurn pre- (Curry Rogers & Forster, 2001, 2004; Wilson, served in Bonatitan is not dorso-ventrally dc- 2002), wliicli has the best preserved and fairly pressed, instead it bcars a prominent axial crest complete skull arnorrg titanosaurs. on the ventral surface that is interpreted to be an 'She skull of Bonatitan shows some differences autapomorphy of this new species. with regards to Saltasaurus, including unfiisttd Amongsaltasaurines, the appendicular bones basipterygoid tubera of the hasisphenoid (in of Bonatitan reigi are more slender than those Saltasaurus these are thick arid fused; Powell, of Saltasaurus and Neuquensaurus, taxa in which 1992, 2003); paraoccipital process located at the these elements have a more robust aspect with same level ofthe occipilal condyle (in Saltasaurus well developed processes (e.g., cnernial crest in they are below that level); and reduced and pos- tlie tibia). The femur is the only appendicular teriorly placed carotid foramen. In Bonatitan, the hone that can be compared with Rocasaurus; it basipterygoid tubera are twice dorso-ventrally is quite similar in both species, only differing in longer than transversely; in contrast, Antarc- the relative size of the distal condyles (in tosaurus and Rapetosaurus have robust and short Rocasaurus are almost equal, whereas in tubera almost as long as wide (Huene, 1929; Bonatitan the medial condyle is larger than the Curry Rogers & Forster, 2004). The basipterygoid lateral one). Thus, the appendicular bones of processes of the basisphenoid are divergent in Bor~atitan(and aiso of Rocasaurus) show a more Bonatitan, while in Antarctosaurus they almost Martinelli & librasiepi: Late Cretaceoi~svertebrates from Rio Negro, Argentina 287 form a straight angle and in Rapetosaurus they Faveoloolithidae Zhao & Ding, 1976 are almost parallel. In consequence, the main axis Sphaerouum erbeni Mones, 1980 of the basipterygoid tubera coincides with the (Fig. 19) main axis of the hasipterygoid processes in Antarctosaurus, while in Bonatitan and ReferreclMaterial. MACN-PV RN 1088:thou- Rapetosaurus the basipterygoid tubera are more sands of isolated eggshell fragments and seven divergent than the basipterygoid processes. eggs almost complete. Among titanosaurids only Bonatitan, Description. The eggs are spherical and the Saltasaurus,Antarctosaurus, and Rapetosaurus diameter varies from 180 to 210 mm. The egg- have a large trigeminal foramen (CN V). This shells are thick and vary from 5 to 6 mm. The foramen is very reduced in Quaesitosaurus morphotype is filispherulithic (small narrow (Kurzanov & Bannikov, 1983) and the other non- spherulites that converge one with another leav- titanosaurid neosauropod (e.g., Madsen et al., ingsurroundingpores; Mikhailov, 1991); the egg- 1995; Berman & Mclntosh, 1978). The optic fo- shells have a multicanaliculate pore system ramen is relatively Large in Bonatitan, Salta- (Mikhailov, 1991). saurus, Quaesitosaurr~s,andRapetosaurus while Comments. The eggshells here described have il is reduced in other neosauropods such a iilispherulithic morphotype, a multicanaliculate as brachiosaurids or dicraeosaurids. The over- pore system, and compactituherculate oxtcrnal or- all comparison with others titanosaurids sug- namentation, a set of features diagnostic of the gest that the cranial morphology of Bonatitan species Sphaerouum erbeni Mones (Casadioet al.,

SAUROPOD EGGS Megaloolithidae Zhao, 1976 The knowledge about sauropod eggs and nest- Gen. et sp. indet. ing behavior increased distinctively over the last few years in South America (e.g., Powell, 1987a; Referred Material. MACN-PV KN 1096: frag- Cbiappe et al., 1998; Casadio et al., 2002). One of ments of eggshells and eight partial eggs. the most important locality from South America Description. These eggshells are thin (about 2 is Auca Mahuevo (northern of Neuqu6n Province; mm trick) and scarcer than the Faveoloolothidae. Anacleto Formation) in which abundant sauro- The more complete egg is subspherical, approxi- pod eggs and embryos in situ has been discov- mately 120 mm in diameter. The external surface ered (Chiappe et al., 1998).Additional Cretaceous is covered with spherical, dome-shaped tubercles eggshell remains have been found in the Rio Colo- that are tightly in contact each other. This type of rado (Calvo et al., 1997b), Los Alamitos (Powell, compactituhercnlate ornamentation is common in 19874, Mlen (Powell, 1987c, 19911, Colorado (Casadio et al., 20021, and Los Blanquitos (Powell, 1994) l'ormations of Argentina; the Mercedes et al., 2002). The morphology of the shell in these Formation of Uruguay (Mones, 1980); the Bauru remains is tubospherulithic (shell units sharply

" .-, -, . . Both the Megaloolithidae and Faveollolithidae tubucanaliculate pore system oofamilies were recognized in these beds (e.g., Comments. The tuhospherulitic morphology Mones, 1980; Powell, 1987a & c, 2003; Chiappe of these remains suggests megaloolithid affini- et al., 1998; Casadio et al., 2002). The eggshells ties and clearly indicates the presence of another preliminary reported from the Allen Formation taxon different to Sphaerouum erbeni. were assigned to Sphaerouum erbeni (Fa- veollolithidae) (Casarlio et al., 2002). In 1990 a TEEKOPODS great abundance of eggshells and nests in the areaof the Bajo de Santa Rosain the upper mem- The record of theropod dinosaurs in the Allen ber of the Allen Formation were discovered indi- Formation is scarce in comparison with other cating an important sauropod nesting ground. Cretaceous formations of Patagonia. The Posteriorly to the discovery, this region was theropods described from the Allen Formation looted and the fossiliferous richness of eggs and are the abelisaurid Quilmesaurus curriei (Coria, eggshells decreased drastically 2001; Kellner & Campos, 20021, and a yet 288 Recri,sta del Museo Argenlino de Ciencias Nutarales, n, s. 6 12), 2004

(Fig. 20A) Rg 19 Sauropod eggshell MACN-PV IZN 1088, Referred Material. MACN-PV RN 1086: an detail of the external surface of the eggshell of isolated tooth. Sphaerouam er hem Mones Scale bar represer~ts Description. The orily noxi-avian theropod re- 2 mm mains report,ed in this present study consists of a small serrated tooth represented hy a fragmen- tary crown (Fig. 20A). For descriptive purposes assigned to this family were reported horn the the most convex serrated edge is interpreted as Cerro Barcino (Aptian; Clinbut I'rovince; Novas mesial and LLie most flat surf:lce of the tooth as & de Valais, 2001; Vickers-Rich el al., 19991, lingual (i.e., the tip of the tooth is inclined dis- Candeleros (Alhian-Cenomanian; Wio Ne6~o)(de tally and lingually). Valais & Apestegriia, 2001), Mata Amarilla The preserved crown height is 19 mm, with a (Turonian; Chubut Province; Novas et al., 1999!, maximum mesio-distal width of I1 mm at the and Anacleto (Santonian; Neuq11i.n Province; base. The mesial carina is slightiy more curved Alcober et a]., 1998) formations. Furthermore, than the distal one. The carina bears about 9 teeth rclerred as Carcharodontosauridae were denticles in 5 nim. Well developed blood grooves collected from the Sgo Luis Basin (Cennmanian; are present between succcsive denticles as occurs Norther Brazil; Vilas-Boas et al., 19991, and in Carcbarodontosauridae, Tyrannosauridae, Adarnantina (Tiironian-Santonian) and Marilia Dromaeosauridae, and Allosaurus (c.g., Currieet (Maastrichtian) formations from Sio Paula and al., 1990). The crown is transversely narrow at Minas Gerais (Brazil; Candeiro, 2002; Candeiro the top, but wide at the botton. The labial sur- el al., 2002). face is dorso-ventrally and mesio-distally convex. The Abelisauridae is another well known Pam- The tip of the crown is slightly inclined lingually ily of basal neotheropods widely doc~imeiltedin On both surfaces, close to the mesial and distal the Late Cretaceous of Patagonia (Bonaparte, edges the enamel is wrinkled, forming obliquely 199'1;Bonaparte & Novas, 1985; Bonaparte et al., oriented barids that extend fro111 the carina to 1990; Coria et al., 2002). Abelisaurid teeth lack the midline of the crown. These bands are more wrinkled enarnel near the carina and lack blood evident on the lingual side (Fig. 20A). grooves between denticles (Bertini, 1996; Comments. Thc wrinkled condition of the Bittencourt & Kellner, 2002). enamel leads us to consider this specimen as The record of a tentatively Carcharodon- cf Carcharodoritosauridae, a feature that was tosauridae in the Allen Formation at the Bajo de interpreted as diagnostic for the family (e.g., Santa Rosa locality is a significant find because Sereno et al., 1996; Larsson, 1996; Candeiro, tlie largo sized members of this family (e.g., 2002). Nevertheless, it is worth mentioning Giganolosaurus carolinii, Carcharodontosa~~rus that carcharodontosaurid teeth has a height of saharicus; Coria & Salgado, 1995; Sereno et al., approximately 100 mm, differing considerably 1996), which proliferated during the Aptian- with regards to the very small taxorl described Tnronian times in South America and Africa, are here. poorly represented in the fossil record during the The most complete record of Carcharo- Coniacian to Maastrichtian times. dontosauridae in Patagonia is Glganotosaurus If the wrinkled enamel of carcharadontosaurids camlinii (Coria & Salgado, 1995) represented by is a diagnostic trait not recordered in others an almost complete skeleton from the Albian- neotheropod taxa, this tooth could represent the Cenomanian Candeleros Formation of Neuq~iiin. first record of the family in the Campanian- In addition, isolated teeth and skeletal remains Maastrichtian of Patagonia, and together with Martinelli & Forasiepi: Late Cretaceous uerlebrales from Rfo Negro, Argentina 289 those specimens from the Maastrichtian Marilia has previously provided Elasmosauridae plesio- Formation (Brazii; Candeiro et al., 2002) may sug- saurs (near Lago Pellegrini; Gasparini & Salgado, gest the persistence of this family throughout the 2000); Lambeosairrinae (Salitral Moreno; Powell, uppermost Crelaceous in South America. 1987b), Hadrosauridae (Pue1i.n; Gonzhlez Riga & Casadio, 2000), and Nodosauridae (Salitral ORNITHISCHIANS Moreno; Salgado & Coria, 1996; Coria & Salgado, 2001) ornithischians; the ahelisaurid Quillne- The occurrence of ornithischian dinosaurs in saurus curriei (Salitral Ojo de Aya;Coria, 20011, the Allen Formation is based on vertebral and a deinonychosaur (Bajo de Santa Rosa; Novas et sacral remains of a Lambeosanrinae (Powell, al., 2003h), and the Carinatae bird Lirnenauis 1987h) and a few isolated bones and dermal plates patagonica (Salitral Moreno; Clarke & Chiappe, of a probable Nodosauridae (Ankyiosanria) from 2001); the titilnosaurids Aeolosaurus sp. (Salitral Salitral Moreno, Rio Negro Province (Salgado & Moreno; Salgado & Coria, 1993) and Rocasaurus Coria, 1996; Coria & Salgado, 2001), and frag- muniozi (Salitral Moreno; Salgado & Azpilicneta, mentary postcraniirl elements of a Hadrosauridae 2000); sauropod eggs remains (Powell, 1987c, (closely related to Kritosaurus australis) frorn the 1991,2003);and isolated mammal teeth (Rougier west of La Pampa Province (Gonzaiez Riga & et al., 2003). The vertebrate taxa studied here Casadio, 2000). increase the knowledge of many taxonomic In the Los Alamitos Formation several skel- groups of vertebrates for the Allen Formation etons of Kritosaurus australis (Bonaparte et al., (see Tables 1-2, and Fig. 21) and provide new data 1984; Bonaparte & Rougier, 1987) have beer1 dis- about the vertebrates that inhabited South covered, representing the best-known record of Arnerica during the Canlpanian-Madstrichtian. this group for the Late Cretaceous of South Among the families identified here, specimens America. Fragmentary remains of indeterminated of continental (terrestrial and fluvial) and ma- Hadrosauridae were also reported from the Paso rine environments are docurnented. Fresh wa- del Sapo (Chuhut Province; Apesteguia & ter taxa include Dipiomystidae, Percichtyidae, Camhiaso, 1999), Coli Toro (Rio Negro Province; Lepisosteidac, dipnoan lungfishes, pipid frogs, Coira, 19791, and La Colorlia (Ilill et al., 2002) for- and cllelid turtles, whereas terrestrial taxa in- mations. clude nladtsoiid snakes, sphenodonts, hadro- saurid, theropod, and titanosaurid dinosaurs. Ornithischia Seeley, 1888 Living ieptodactylids inhabit both terrestrial as Ornithopoda Marsh, 1871 well ai; freshwater environments; nevertheless, Haclrosauridae Cope, 1869 the closer affinities between the specimens ofthe Gen. et sp. indel. Allen Formation and the strictly aquatic living (Figs. 20B-C) genus Caudiuerbera that livas in rivers and streams (Cei, 1962) suggests the presence of an- Referred Material. MACN-PV RN 1085: five other freshwater taxon. maxillary fka~mentsand several tooth fragments. The marine taxa are scarce and fragmentary, Description. The best preserved fra,ment of and represented by at least one Laxon of a maxilla (Fig. 20R) recovered at Bajo de Santa Elasmosauridae plesiosaur Within plesiosaurs, Rosa shows same-sized alveolii located close to this family was interpreted as reiated to coastal each other and separated by alveolar septa. De- environments (Gasparini et al., 20011; disarticii- spite the lack of synapomorphies, the morphol- lated remains are lrequently fourid in association ogy and size of tile maxilla resembles that ob- with continental vertebrates (c.g., Gasparini & served in some ornithopod hadrosaurs, such as Salgado, 2000; Gasparini et al., 2001). Kritosaurus australis (Bonaparte et al., 1984; Some of the dinosaurs found at Bajo de Santa Bonaparte & Rougier, 1987) from the Los Alamitos Rosa arc often associated with mixed environ- Formation. The teeth are poorly preserved; in the ments. IIadrosaurids and some sauropods were enameled labial surface they have a strong me- frequently recovered in coastal rilarine environ- dian carina (Fig. 206) that is only present in ments (e.g., shallow marine or estuarial depos- I-Iadrosauridae (Weishampel & Horner, 1990). its; Horner, 1979; iucas & Hunt, 1989; Weishampel & Iiorner, 1990; Dodson, 1990; DISCUSION L6pez-Martinez et al., 2000). The two types of eggs (Faveoloolithidae and Me~aloolothidae)re-

"- " and Rio Negro Provinces (Argentma) This tinit he restricted to a water-satured atmosphere or Fig. 20. l'heropod. A. MACN-PV RN 1086, tooth of cf.' Carcharodontosauridae indet. in lingual view (arrow indicates mesial side). Ornithopod. B. MACN-PV RN 1085, fragment of maxilla of Hadrosauridae indet, in lingual view; C. fragment of tooth of I-Tadrosauridae indet. Scale bar represents 5 mm in A and C, and 10 mm in B. wetlands (e.g., Seymour, 1979). Megaloolithidae O,jo de Agua, Cerro Mesa, Bajo de Los Menucos, remains were frecuently documented in low-gra- and Lago Pellegrini localities suggest fresh wa- dienl floodplain erivironments in the Rio Colo- ter to salty Lagoons; whereas the presence of the rado Subgroup 0f'Neuqui.n (Dingus et al., 2000) briozoan Fungela in some localities (Salitral Ojo as well as in tidal flats (near sea shore) environ- de Agua and Lago Pellegrini) into the uppermost ment from the Late Campanian of Spain (Lopez- level of the Allen Formation (near the contact Martinez et al., 2000). Thus, both types of egg- with the marine Jaguel Formation) indicates shells indicate a wet and low land environment. marine conditions (Wichmann, 1.927; Ballent, The evidence of the vertebrates presented 1980; NBhez & Concheyro, 1996; Echevarria, here collected at Bajo de Santa Rosa is con&.ru- 1999; Nhfiez, 1999). As previously mentioned, it ent with the paleoenvironmental reconstruction is clear that the Alien Formation (and also the of the Allen Formation based on geological stnd- Loncoche Formation) represents the transition ies: a continental environment developed close between the fully continental Neuqu6n Group to a marginal-litoral place (Andreis et at., 1974 ; and the fully marine Jaguel Formation (Malargue Casamiquela, 1978; Uliana & Dellap6, 1981 ; Group) in nortliern Patagonia (e.g., Page et al., Barrio, 1990; Casadio, 1994; GonaBlez Riga & 1999; and references here cited) Casadio, 2000). This paleoenvironmental recon- struction explains the mixed association of ver- Comments about Campanian- tebrates i:ornposed by terrestrial, freshwater, and Maastrichtian South American vcrtebrale- marine coastal taxa. bearing formations In addition to the vertebrate remains recov- Most of the vertebrates discovered in the ered at Bajo de Santa Rosa, fossil wood (Andreis lower member of the Allen Formation represent el al., 1991), palm fruit (Ancibor, 19951, and two taxonomic groups of Gondwanan affinities species oFPodocarpaceae conifers (Ccrcoporoxylon (Bonaparte, 1986b) such as Diplomystidae, greg~rssiiandPodocarpoxyEongarciae; Del Fueyo, Pipidae, Leptodactylidae, Chelidae (that during 1998) in the Alien Formation indicate the pres- the Cretaceous only inhabited the Patagonian ence of a continental environment. region; Broin & de la Fuente, 19931, Madtsoiidae, The invertebrate fossils such as gastropod, cf Carcharodontosauridae, and Saltasaurinae, bivalves, ostracods, hriozoans, and foraminifera and the influence of Laurasic components sucli collected near the Bajo de Santa Kosa, Salitral as I-Iadrosauridae and Nodosauridae. This mix- ilfurtinelli & Forasiepi: Late Cretaceous uerlebrates from Rio Negro, Argentina 291

Fig. 21. Squematic reconstruction of the landscape at Bajo de Santa Rosa, Rio Negro Province, Argentina, during the Late Cretaceous Allen Formation. Drawing made by Jorge L. Blarrco.

ture of taxa has been correlated with th-a con- dactylidae, Chelidae, Plesiosauria, 'Madtsoiidae, nection between South America and North Titanosauria, Theropoda, and Hadrosauria. America through Central America at the end of Thc Los Alamitos Formation (Campanian- the Cretaceous ie.g., Anderson & Schmidt, 1983; Maaslrichtianj is exposed over the southeast of Ronaparte, 19866). Rio Negro Province (Bonaparte et al., 1984).The The available evidence from Campanian- vertebrate assemblage is widely diverse; the taxa Maastrichtian vertebrate-bearing formations of recovered include Batoidea, Semionotidae, South America provide a more complex and di- Lepisosteidae, Siluriformes, Perciformes, and verse vertebrate association than that reported Dipnoi (Ciorie, 1987); Pipidae and Leptodac- until the present in other Gondwanan localities. tylidae (Bica, 1987); Meiolanidae and Chelidae The entire information available from several (Brain, 1987); Madtsoiidae (Albino, 1986, 1987, units of South America such as the Loncoche, Los 1994); Hadrosauridae (Bonaparte et al., 1984; Alamitos, La Colonia, Los Blanquitos, Yacoraite, Bonaparte & Rougier, 1987); Titanosauridac El Molino, Adamantina, and Marilia formations (Powell, 1987a; Salgado et al., 1997bj; and diverse show a similar fossil vertebrate composition, with groups of non-tribosphenic mammals (Bona- relatively few differences between the partc, 1986a, 1987, 1990, 1992, 1994,2002). Patagonian and extra Patagonian South Ameri- The La Colonia Formation (Campanian- can records (Table 3). Maastrichtian) is exposed in the north-central The Loncoche Formation (Late Campanian- Chubut Province (Pascual et al., 2000). Fossil ver- Early Maastrichtian) extends over southern tebrates include Diplomystidae (Bovcon, 2002); Mendoza Province and the west of La Pampa Elasmosauridae and Polycotylidae (Gasparini & Province. Recent fieldworks provided signifi- de la Fuente, 2000); Meiolanidae and Chelidae cantly new vertebrate data (Gonzilez Riga, 1999). (Gasparini & de la Fuente, 2000); Madtsoiidae These findings include: Rajiformes, Lepisostei- (Albino, 2000); Crocodyiiformes (Hill et al., 2002); dae, Percoidei, Teleostei, Ceratodontidae, ?Lepta- Abelisauridae and I-Iadrosauridae (Bonaparte et 292 Reuista del Museo Argenlino de Ciencias NaluraEe,~,n. s. 6 (21, 2004

Table 3. Comparison of the ibssil vertebrates of several continental Late Crclaccous Formations of South America. In black are highlight taxa with brackish or marine affinities.

Loncoche Allen Lor La Salta El Bauru Aianiitos Colonir Group Mohilo Group

Hajiforines Chondriclithyes indet. Pyenodontiformes: Pyenodontidae Srrnionotiformes: Seinionotidse Lepisoiteiformes: Lepisostoidae Osteoglossiformcs: Osteoplossidae Characiformos Sifuriformes: Ariidae Siluriformes: DiplorriysLidae Siluriibmies: Andinichthyidae Siluriformes: Doradidae Siluriforines indel. Perciformes indel. Perciformes: Percichthyidse Dipnoi Anura: Pipidae Neobatrachia: Leptodactylidae Clioionia: Podocnemididae Chelonia: Chelidae Chelonia: Meiolanidae Lepidosauriformcu: Sphenodontia Plesiosnuria: Elasmosauridae Plesiosaurin: Polycotylidso Serpentes: Madtsoiidae Serpentes: Aniiioidea Mesoeiicrocodylia Theropoda: Aboiisauroidea Thoropoda: Carcharndontosauridae Thoropoda: Spinosauridao Avialae Sauropoda: Titanosauridae Ornithopoda Aiikylosnuria Mammalia: Dryolcstoidcn Maiilmaiia: Gondwanatirrria Mammnlia: Multituberculrta Mammalia: Eutheria

al., 1990; Hill et al., 2002); and Reigitheridae aPipidae was described (Reig, 1959; BAez, 1981). (Pascual et al., 2000), Dryolestida, and Multi- From the Los Blanquitos Formation (PirguaSub- luberculata (Rougier et al., 2000, 2001). group) a fragment of titanosaurid (Powell 1979; Several Campanian-Maastrichtian units Powell, 2003) and a maniraptoran (Powell, 1979; (Salta Group) in northwest Argentina have pro- Novas &Agnolin, 2004) were described. From the vided continental vertebrate remains. From the Yacoraite Formation (Balbuena Subgroup), Las Curtiernbres Formation (Pirya Subgroup) Kajiforrnes (Powell, 1979); Siluriformes (Cione Martinelli & Forasiepi: Late Cretaceous ue~.tebralesf'ion Rio Negro, Argerltina 293 et al., 1984; Cioiie & Pereira, 1985); Pycno- The case of mammals dontiformes (Benedetto & Sanchez, 1971); The Mesozoic mammals are a relatively re- Eusuchia (Gasparini & Buffetaut, 1980); and di- cent group of vcrtehratcs recovered in Sonth nosaur and bird tracks (Alonso & Marquillas, America (Ronaparte & Soria, 1985) that liave 1986) were reported. From the IdechoFormation provided new data about the evolution of the (I',alhuena Snbgroup), Titanosauridae Saltasan- mammalian clades in Gondwana. Tiie richest lo- rine, Noasauridae, Enantiornithine, a possible calities of South America are the Campanian- oviraptorosaur, and indeterminate nonavian Maastrichtian Los Alamitos and La Colonia for- theropod teeth (Bonaparte & Powell, 1980; mations (e.g., Bonaparte, 1994; Pascual et al., Ctiiappe, 1993; Frankfurt & Chiappe, 1999) were 2000); other units (Allen, El Molino, and reported. Adamaiitina formations) until now only have Tlie El Molino Formation (Puca Group; provided few and isolated remains (Bertini et al., Maastrichtian-Danian) extends over the south- 1993; Gayet el al., 2001; Rougier el al., 2003;). center of Bolivia (GayeL et al., 1991). The verte- The inarnmalian Campaiiian-Maastrichtian brates were broadly described and discussed in record of Soutli America includes: Dryoiestoidea several works (e.g. Gayet, 1991; Schultze, l991a (Mesungulatidae, Reigithcridae, and Dryoles- & h; Gayet & Meunicr, 1998; Gayct et al., 2001, tidae), Triconodonta, Gondwanatheria, and 2003). An overview of all taxa recovered froin the Multituherculata (e.g., Bonapartc, 1986a, 1987, El Moliiio Formation is available in Gayet et al. 1990, 1992, 1994, 2002; Pascual et al.; 2000; ('1991; 2001 and references; sec Table 3). Rougier et al., 2000, 2003). The maminaliari The Bauru Group represents one of thc rich- record from the Adamaritina Formation consist est tetrapod assembiagca of Upper Cretaceous of of a f'ragmentary lower jaw, which was originally Brazil (Turonian to Laie Maastrichtian) that described as a placental xiarrimal (Ber1;ini et al.,

u Adamantina (Turonian-Santonian) and Marilia be evaluated cautiously. (Late Maastrichtian) formations inany fossil ver- The Dryolestoidea is at the monicnt tlie most tebrates were recovered including: Dipnoi, diverse and largely documented group of non- Lepisosteidae, Osteoglossiformes, Characi- tribospbonic mammals recognized in several Late Sormes, Pcrcilbrmes, and Siluriformes (Gayct & Cretaceous localities of South America. Brito, 1989); Leptodactylidae (BaBz and Peri, Campanlan-Maastrichtian Palagonian dryoles- 1989); Podocnemididae (e.g.,Kischlat et al., 1994); toids are widely docuniented in the I,os Alainitos ?Iyania (Estes and Price, 1973);hniiioidea(Zaher (Bonaparte, 1966a, 1990, 2002) and L>aColonia et al., 2003); ?Placentaria (Bertini et al., 1993); formations (Rougier et al., 2000, 2001), and only Mesoeucrocodylia (e.g., Price, 1950; Carvalho & a few specimens were recently found in the Allen Bertini, 1999); Abelisauridae (e.g., Bertini, 1996; Formation (Rougier el al., 2003). Santucci & Berbini, 2001; Kellner & Campos, Older possible dryolestoid reports from 2002); Carcharodontosauridae (Candeiro, 2002); Patagonia come from the Santonian Portezuclo Spinosauridae (Candeiro et ai., 2002); and Formation (Neuquen Group; Neuquen Provincc; Titanosauridae (e.g., kid&Vizzoto, 1971; Keii~ier Coria et al., 2001; Coria, pcrsonal comrnunica- and Azevedo, 1999; Powell, 2003). tion); in addition, another specimen originally A preliminary comparison at a supragenericdl described as a pruhable marsuipial (Goin et al., level suggest strong affinities among the South 1986) fiom the Anacleto Formation (Neuquen American vertebrate-bearing units (Table 3) Group; Paso Cordova, Rio Negro Province) could Nevertheless, some taxonomic groups are only be tentatively assigned to the Dryolestoidea. The restricted to one geographical region; fbr exanlple jaw of the Paso Cordova specimen is high with Chelidae, Meiolanidae, Sphenodontia, Gondwa- the ventral edge slightly convex and transversely natheria, and Muitituberculata are until now rounded, the masseteric fossa is deep, the lingual unly recognized in Patagonia. These differences alveolar level is set notahiy more ventrally than observed in the taxonomic compositon of thc ver- the lingual one, the alveoli decrease backwards tebrate assemblages of Patagonian and extra- and are transversely wide and very ailtero-pos- Patagonian regions could be artificial due to the teriorly short resembling the condition of Ida

~, different paleoenvironmental coilditions devel- Gelfo & Pascual, 1999) from the Early Paleocei~e oped in distant geographical areas. ,>, Plaza Hinncul, Neuquen), the Bajo de Santa Rosa locality, Rio Negro Prov- B. J. Gonz6iez Riga (Centro Regional de ince, Argentina (Table 1and 2) provide new data lnvestigaciones Cientificas y Tecnicas, Mendoza), about the diversification and compositional ver- A. M. Albino (Universidad de Mar del Piata, tebrate assemblage of the Campanian- Buenos Aires), F E. Novas (MACN), A. Lbpea- Maastrichtian Allen Formation (Malargiie Arharello (Museum fur Naturknnde Humboldt Group). UniversitAt, Berlin, Germany), A. Bhez The vertebrates recognized are: cbondrich- (IJniversidad de Buenos Aires, Argentina), A. C. thyaris; diplomystid, lepisosteid, cf percichthyid, Garrido (Museo Municipai .d!arrricn Funess, Plaza and dipnoid osteichthyans; pipid and iepto- I-liuncul, Neuqubn), M. Gayet (Universite Claude dactylid anurans; chelid turtles; sphenodonts; Bernard, France), G. W. Rougier (University of elasmosaurid plesiosaurs; madtsoiid snakes; Louisville, KY, USA), C. R. A. Candeiro and I,. faveoolitid and megaloolithid eggshells; and Avilla (Universidad Federal do Rio de Janeiro, hadrosaurid, ci: carcharodontosaurid and Brazil), A. Camhiaso (MACN), S. de Valais and N. titanosaurid dinosaurs. Bovcon (Museo PaleontolSgico <

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Reeibido: 19-111-2004 Aceptado: 25-X-2004 Murtinelli & Forasiepi: Idate Cretaceous uerleln-ates from Rio Negro, Argentina 305

Appendix. Table of measurements of the postcrBnial banes of Bor~atitanreigi gen, et sp, noo. An asterisk (*) indicates an estimated measurement.

Cervical vertebra (MACN-PV ltN 1061) Height of rcntrum (antenor) 30 mm Wzdtii of centlum (antal~or) 32 ulm Length of centrum 124 mm

Dorsal vertebra (MACN-I'V RN 821) Total heighi Height of ecntrum Width of centruin Leiinth- of centrum Distance between prezygapophyses

Antr:rior oaudzal vertebra (MACN-PV RN 821) Total height Height ofcentrum Width of centrum Total length of centrum Length of the centrurn without posterior articular surfacaeo

Middle caudal vertebra (MACN-PV RN 821) Neural arch height 75 mm Maxiinunl distance between prezygapophyses 56 mm Maximum dist,anee between postzygapophyses 38 mm UisLance between prczygapophysis and anterior border of neural spine '73 mrn

Humerus (MACN-PV RN 821) Total length I'roximal width Distal widti, Miriiiriuin transversal diameter of tilo diaphysis

Ulna (MACN-PV RN 1061) Total length Proxirnal width Distal width

Radius (MACN-PV RN 1061) Total length 195 mm Proximal width 85 mm* Distal width 60 mm*

Femur (MACN-PV RN 821 and MACN-PV RN 1081) Total length 585mm 455 mm Proximal width 158rmm 125mm Distal width 145 urn 120 mm*

Tibia (MACN-PV RN 821 and MACN-PV RN 1061) Total length Proximal width Distal width

Fibula (MACN-PV RN 821) Total length Proxiinal width Distal width

Metatarsal 1 (MACN PV RN 821) 'rota1 longth Proxtmal wrdth D~stalwidth

Metatarsal 111 (MACN-PV RN 1061) Total longth Praxiinbl widtll Distal width