Rocasaurus muniozi Salgado and Azpilicueta, 2000

Garcia, Rodolfo A. & Salgado, Leonardo, 2013, The titanosaur sauropods from the late Campanian-early Maastrichtian Allen Formation of Salitral Moreno, Río Negro, Argentina, Acta Palaeontologica Polonica 58 (2), pp. 269-284 : 274-282

Rocasaurus muniozi Salgado and Azpilicueta, 2000

Figs. 5B , 6 , 7 , 8 .

Holotype: One cervical centrum, MPCA−Pv 46/1; one cervical neural arch, MPCA−Pv 46/2; two dorsal centra, MPCA−Pv 46/7 and MPCA−Pv 46/8; and four neural arches, MPCA−Pv 46/3, MPCA−Pv 46/4, MPCAPv 46/5, and MPCA−Pv 46/6; one mid caudal vertebra, MPCA−Pv 46/9; one posterior caudal vertebra, MPCA−Pv 46/10; both ischia, MPCA−Pv 46/11 (left) and MPCA−Pv 46/14 (right); left pubis, MPCA−Pv 46/15; left ilium, MPCA−Pv 46/12 and fragment of the right one, MPCA−Pv 46/13; left femur, MPCA−Pv 46/16. All from Salitral Moreno locality, Rio Negro, Argentina, Campanian– Maastrichtian, Upper Cretaceous.

Referred material.—Cervical vertebrae, MPCA−Pv 858, MPCA−Pv 859 and MPCA−Pv 860; cervical neural arch, MPCA−Pv 46; anterior caudal vertebrae, MPCA−Pv 47, MPCA−Pv 48, MPCA−Pv 57, and MPCA−Pv 60; mid caudal vertebrae, MPCA−Pv 49 and MPCA−Pv 58; posterior caudal vertebra, MPCA−Pv 50; distal caudal vertebrae, MPCA−Pv 51, MPCA−Pv 54, MPCA−Pv 56, and MPCA−Pv 56/1. All from Salitral Moreno locality, Rio Negro, Argentina, Campanian–Maastrichtian, Upper Cretaceous.

Description

Cervical vertebrae.—The cervical vertebrae are represented by one centrum and a partial neural arch of the holotype (MPCA−Pv 46/1, 46/2). There are also three undescribed posterior cervical vertebrae (MPCA−Pv 858, MPCA−Pv 859, and MPCA−Pv 860), which are here referred to Rocasaurus muniozi .

The cervical centrum of the holotype is extremely depressed, but this arises from its bad preservation ( Salgado and Azpilicueta 2000). However, it is still possible to observe a dorsally open neural canal, which is laterally limited by the sutural rugosities by which the centrum articulated to the neural arch. The lack of fusion between centrum and neural arch suggests that the specimen is a juvenile.

The centrum of the cervical vertebrae is opisthocoelous. In lateral view, it shows a badly preserved, low pleurocoel, which occupies most of the lateral face of the centrum (41%). Ventrally, the bases of the laterally projected parapophyses are present. The neural arch of the type material presents some deformation, which does not allow a precise identification of its structures.

The vertebrae MPCA−Pv 858 to 860 ( Fig. 6 ) come from approximately 200 m east of the quarry that produced the holotype of Rocasaurus muniozi . The centra are low, with the pleurocoels somewhat more developed than in the type specimen (it occupies 47% of the centrum length) (SOM 2).

The pleurocoel is deep, reaching almost to the sagittal plane of the centrum. In MPCA−Pv 860, this depression is divided by an anteroposteriorly directed thin lamina, also present in Saltasaurus ( Powell 1986, 2003), Bonatitan ( Martinelli and Forasiepi 2004) and Rinconsaurus ( Calvo and Gonzalez−Riga 2003) . Both centrum and neural arch are composed of highly spongy osseous tissue.

The ventral face of the centrum is plane; it has only a shallow concavity produced by the lateroventral elongation of the parapophyses. The neural canal is relatively broader than in the holotype. The neural arch height, excluding the neural spine, which is not preserved in any specimen, is 56% of the total vertebral height.

The prezygapophyses, only preserved in MPCA−Pv 859, are low and notably developed; the articular surface is ellipsoid with a length of 4.5 cm on its greater axis ( Fig. 6A ). The postzygapophyses are more robust than the prezygapophyses. The articular surface is tear−drop−shaped, and has a length of 5 cm in MPCA−Pv 859 and 5.7 cm in MPCA−Pv 860. The greater axis of the articular surface of the postzygapophyses, dorsoventrally oriented, lies parallel to the sagittal plane of the vertebra.

In MPCA−Pv 858 to 860, a well developed posterior centrodiapophyseal lamina roofs dorsally an anteroposteriorly extended pleurocoel ( Fig. 6A, C ). The postzygodiapophyseal lamina is well developed; notably, this lamina is distally forked in MPCA−Pv 860. The spinodiapophyseal is also well developed. Dorsal vertebrae.—There are two vertebral centra (MPCAPv 46/7, MPCA−Pv 46/8) and four neural arches (MPCA−Pv 46/3, MPCA−Pv 46/4, MPCA−Pv 46/5, MPCA−Pv 46/6), two of which are only represented by their lateral portions ( Fig. 7 ). The two centra are strongly opisthocoelous, bearing small pleurocoels that are placed high on the centrum, practically at the base of the neural arch ( Salgado and Azpilicueta 2000) (SOM 2).

The lateral faces of the centra are flat, both anteroposteriorly and dorsocaudally. Their ventral faces are deeply concave anteroposteriorly. The two centra show, in dorsal view ( Fig. 7A 2 ), a wide neural canal laterally bounded by rugose, low neural peduncles.

From the four neural arches preserved, probably three belong to a fifth, eighth, and tenth dorsal, respectively. The absence of fusion between the centra and the arches, as in the cervical vertebrae, suggests this ia an immature animal. The anteriormost neural arch preserved (the fifth) belongs to the holotype ( Salgado and Azpilicueta 2000: fig. 3); it is transversely wide, with a posterodorsal inclination of 50 ° to the hor−

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izontal. In anterior view ( Fig. 7B ), it exposes a broad surface, extending ventrodorsally, along its entire extent, by a prespinal lamina. The neural spine, notably wide, unites to the well−developed diapophyses by means of the spinodiapophyseal laminae. The diapophyses are dorsolaterally projected, being ventrally united to the modestly developed parapophyses by means of the paradiapophyseal laminae, and to the prezygapophyses by means of the prezygodiapophyseal laminae. Both the diapophyses and parapophyses are strongly anteroposteriorly compressed. The prezygapopyses are broad, lanceolate, and their planes form a V, with an angle of nearly 75 °.

In posterior view ( Fig. 7C ), it is possible to observe a stout postspinal, which goes from the contact between the postzygapophyses, one of which is very incomplete, to the neural spine ( Salgado and Azpilicueta 2000: fig. 3). The centropostzygapophyseal laminae join to the posterior centrodiapophyseal laminae at the base of the neural arch. The posterior centrodiapophyseal laminae is the most developed lamina. Towards its distal end it is expanded.

None of the preserved neural arches possesses a hyposphene, like other titanosaurs ( Salgado et al. 1997b; Powell 2003). Considering the preserved four neural arches, it may be inferred that their width decreased toward the posterior vertebrae.

The dorsal neural arch of the 8th? is incomplete and lateromedially deformed, but it is possible to see some details that are not appreciable in other materials ( Fig. 7B ). The posterior centrodiapophyseal laminae is notably bifurcated at its base ( Salgado and Azpilicueta 2000: fig. 5), which produces a triangular depression between the bifurcation and the base of the neural arch. From the anterior ramus of this bifurcation, the accessory posterior centrodiapophyseal laminae, according to Salgado et al. (2005), originate three small, parallel laminae: the mid lamina (the greater of the three) is the posterior centroparapophyseal laminae; dorsal to it there is the unnamed parapophyseal lamina, and ventral is the accessory laminae. These laminae contact the anterior centroparapophyseal laminae, which are very sharp in this species. The unnamed parapophyseal lamina originates from a non−bifurcated portion of the posterior centrodiapophyseal laminae.

The dorsal neural arch of the 10th? vertebra is complete and somewhat anteriorly inclined, perhaps as a consequence of deformation post−mortem ( Fig. 7C ). In anterior view, the most distinctive feature of this element is a robust prespinal lamina (prsl) that is directed from the distal extreme of the neural spine to its contact with the prezygapophysis. From the contact between the postzygapophyses and the neural spine originates the posl, which is internal and parallel to the spinopostzygapophyseal laminae. Ventral to the postzygapophyses, there are the well developed but short centropostzygapophyseal laminae. This reveals that, in this vertebra, unlike the fifth? dorsal vertebra, the postzygapophyses are closer to the neural canal.

Anterior caudal vertebrae.—The anterior caudals are represented by four elements (referred materials, MPCA−Pv 47, MPCA−Pv 48, MPCA−Pv 57, MPCA−Pv 60, see SOM 2), all procoelous ( Fig. 7D, F ). The procoely becomes more pronounced towards the most posterior vertebrae.

These vertebrae are short and tall, wider than long and, as noted by Salgado and Azpilicueta (2000), all the caudal vertebrae possess a deep ventral cavity divided by a longitudinal septum, which is a character shared with Saltasaurus Powell, 1986 . This cavity reaches its greatest depth in the mid caudals (here, it is 50% of the centrum depth) and becomes shallow in the posterior caudals ( Fig. 7E 2 ).

Throughout the broken surfaces of MPCA−Pv 48 it is possible to observe the cavernous osseous tissue. The pleurocoel is very small and placed on the ventral half of the lateral face, equidistant from the anterior and posterior margins, just below the base of the caudal rib. On the left lateral face of vertebra MPCA−Pv 57, the border that limits the posterior articular surface of the centrum presents an osseous overgrowth, with a lateral continuation of the centrum, probably pathological.

Mid caudal vertebrae.—All the mid and posterior caudal vertebrae (both in the holotype MPCA−Pv 46/9 and referred

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material, MPCA−Pv 49 and MPCA−Pv 58, see SOM 2) are strongly procoelous. In these vertebrae ( Fig. 7E ), characteristically, the posterior articulation of the centrum is placed slightly dorsally with respect to the mid longitudinal axis of the centrum.

In posterior view, the articulation shows a peripherical rim which completes the contour of the centrum. The rim becomes thicker, more robust, in the articulation for the haemapophyses, which resembles the condition observed in Titanosauria gen. et sp. indet. 4. On the lateral faces of vertebrae MPCA−Pv 49 and MPCA−Pv 58, two small, vertically aligned pleurocoels are observed. The lateral face of the holotype is convex and lack pleurocoels. Internally, the caudal vertebrae, as noted by Salgado and Azpilicueta (2000), present a great development of spongy tissue, composed of numerous and irregular cells.

The prezygapophyses are relatively short, surpassing the anterior border of the vertebral centrum ( Fig. 7E 1 ). The articular faces are well developed and elliptical, their planes inclining medially at 45–50 ° to the horizontal.

In the mid and mid−posterior caudals, the neural arches are placed on the anterior half of the centrum, and are strongly inclined backwards, the neural spine surpassing the posterior border of the vertebral centrum ( Fig. 7E 1 ). The neural arches are low, much lower than in other titanosaurs (e.g., Neuquensaurus ).

The postzygapophyses are posteriorly directed to reach the mid−posterior portion of the centrum. Their articular facets are subcircular and incline lateroventrally 45 °. The articulations for the haemapophyses are well developed in all caudal vertebrae. In these vertebrae (in MPCA−Pv 58 and in the holotype), the ventral cavity attains its greatest development, perforating almost the whole vertebral centrum ( Fig. 7E 1 ).

Posterior caudal vertebrae.—As in the mid caudals, the posterior caudal vertebrae (MPCA−Pv 46/10 and referred material, MPCA−Pv 50, see SOM 2) are procoelous ( Fig. 7G ). Their ventral cavity is not as deep as in the mid caudals; however, this cavity occupies the greater part of the ventral face of the centrum. The pleurocoel is small and it is placed on the dorsal portion of the lateral face of the centrum. The neural arch is low; the prezygapophyses have a curvature towards the mid−line, their articular surfaces being placed very close one to each other.

Posterior−distal caudals.—The material that Salgado and Azpilicueta (2000: fig. 8D–F) referred to Rocasaurus is composed of four vertebral centra (MPCA−Pv 51, MPCA−Pv 54, MPCA−Pv 56, MPCA−Pv 56/1), some of which are partially preserved. These vertebrae are strongly compressed dorsoventrally. The ventral cavity, typical of this taxon, is here a shallow depression, except in MPCA−Pv 54 where a relatively deep depression is observed. The most notable character of these distal vertebrae is the posterior articulation of the centrum, which is wide and flattened ( Fig. 7H ). The vertebral centrum, as seen in MPCA−Pv 54, is completely pneumatic, composed by large cavities limited by strong septa.

Femur.—The femur of Rocasaurus muniozi is straight. On its lateral margin, immediately below the greater trochanter, there is a strong curvature, the so−called lateral bulge ( Fig. 8A 1 ); this has been proposed as a synapomorphy of Titanosauriformes ( Salgado et al. 1997b; Upchurch 1998; Wilson and Sereno 1998). The angle between the intersection of the virtual extension of the dorsal surface of the femoral head, and the line that contains the most lateral point of the lateral bulge, is 124 °, which is the greatest angle observed in the three femora described in this work ( Figs. 5 , 8A 1 ).

The robustness index is 0.16 (see SOM 2), intermediate between Aeolosaurus sp. and the Titanosauria gen. et sp. indet. described below. This element is anteroposteriorly compressed through the entire diaphysis and proximal epiphysis. Distally, the bone becomes more cylindrical, with a mediolateral/anteroposterior index of 1.83 (see SOM 2).

The tibial condyle is anteroposteriorly well developed, whereas the lateral or fibular condyle is more lateromedially developed ( Fig. 8A ). The intercondylar groove extends through the first distal third of the bone, continuing towards the upper part by a low crest, which is more developed than in other titanosaurs. This crest decreases proximally to disappear in the proximal third of the bone.

Ilium.—Both elements are preserved; the left one, which is complete (MPCA−Pv 46/12; Fig. 8B ), and the acetabular portion of the right one (MPCA−Pv 46/13). The pubic peduncle is perpendicular to the axis of the main body of the bone (pre− and postacetabular lobes). The preacetabular lobe is broad (being 29 cm in dorsoventral depth), semicircular, and unlike other titanosaurs ( Saltasaurus, Powell 2003 ; Neuquensaurus Salgado et al. 2005 ) it is not laterally twisted, although this could a result of deformation. The postacetabular lobe is slightly smaller than the preacetabular lobe, and of a rather elliptical contour ( Fig. 8B , SOM 2). On the posteroventral portion of the postacetabular lobe, a rugose surface is clearly visible, the articulation for the ischium.

Pubis.—The left pubis (MPCA−Pv 46/15) is a laminar bone with a slight torsion on its longitudinal axis ( Fig. 8D ). The bone thins abruptly from lateral to medial parts. A well−developed obturator foramen is near the acetabulum and the articulation for the iliac peduncle. This foramen opens on the medial side of the pubis at the bottom of a deep obturator fossa, which practically reaches the border of the iliac peduncle. Distally, the pubis is slightly expanded.

Ischium.—Both ischia are preserved (MPCA−PV 46/11, MPCA−PV 46/14), the first being nearly complete ( Fig. 8C ). This bone is mostly laminar, but the pubic peduncle is robust; it decreases in thickness distally. The contact with the pubis is greater than in Saltasaurus and Neuquensaurus ( Salgado and Azpilicueta 2000) . The acetabular surface is almost twice as thick as the rest of the bone. Immediately below the acetabular surface, both on the medial and lateral faces, asymmetrical protuberances are observed, which are interpreted as muscular attachments.

Titanosauria incertae sedis

Gen. et sp. indet. 1

Fig. 9 .

Material.—Two mid caudal vertebrae, MPCA−Pv 866 and MPCA−Pv 867; right humerus, MPCA−Pv 33; right tibia, MPCA−Pv 33/1; right femur, MPCA−Pv 33/2. All from Salitral Moreno locality, Rio Negro, Argentina, Campanian– Maastrichtian, Upper Cretaceous.

Remarks.—This specimen was associated with the holotype of Rocasaurus muniozi . Because of the slenderness of its appendicular bones and the morphology of the caudal vertebrae, it is obvious that it belongs to another, more gracile, non−saltasaurine species; it also clearly differs from Aeolosaurus in many features, as mentioned in the description.

Description

Caudal vertebrae.—The caudal vertebrae MPCA−Pv 866 and MPCA−Pv 867 are strongly procoelous, with their lateral faces flat and relatively high. The ventral face of the centrum is slightly convex; the articulations for the haemal arches are poorly developed. The neural arch, preserved only in MPCAPv 867, is placed on the anterior half of the centrum, as in other titanosaurs, and the neural spine is low and transversely wide ( Fig. 9B , SOM 3). The prezygapophyses are anteriorly extended, surpassing the anterior border of the centrum by 46% of centrum length. The articular surfaces of the prezygapophyses are practically parallel to the axial plane. The postzygapophyses are located at the base of the neural spine, approximately at the middle of the centrum. There is a distinctive furrow between the articular surfaces of the postzygapophyses.

Humerus.—The right humerus (MPCA−Pv 33) is the smallest of the three humerii here described. The humeral head and the deltopectoral crest are partially preserved ( Fig. 9C ). The deltopectoral crest is small and higher than in Aeolosaurus (MPCA−Pv 88/A) and other titanosaurs (e.g., Neuquensaurus ). The robustness index cannot be calculated because the distal portion of the humerus was not preserved. As in other titanosaurs (Alejandro Otero, personal communication 2010) the bone presents a sharp lateral ridge on its distal half, but in this specimen this structure is particularly well developed.

Femur.—The right femur (MPCA−Pv 33/2) is slender; its robustness index is only 0.15 (SOM 3), the lowest value of the three femora described here. The mediolateral/anteroposterior index (M.A. index = 1.56) is also the lowest recorded in Salitral Moreno, being closer to the values obtained in Neuquensaurus ( Otero 2010) . A feature that distinguishes this ma−

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terial from Rocasaurus and Aeolosaurus is its poorly developed anterior intercondylar groove, which is only pronounced in the distalmost portions of the condyles ( Fig. 9A ). The lateral bulge is close to the greater trochanter, closer than in Rocasaurus . The angle of the intersection of the virtual extension of the dorsal surface of the femoral head and the virtual extension of the line that contains the most lateral point of the lateral bulge (119 °), is higher than in Aeolosaurus (114 °) but lower than in Rocasaurus (124 °) ( Fig. 5 ).

The posterior face of the femur is plane along its shaft, while the anterior surface is plane only proximally (near the lateral bulge), and the rest of the shaft being convex.

Tibia.—The right tibia (MPCA−Pv 33/1) is almost complete, only lacking the proximal lateral portion and the distal condyles ( Fig. 9D ). The bone is gracile, 35% shorter than the femur (SOM 3). Proximally, the medial surface of the tibia is slightly convex; this convexity accentuates distally. The incomplete preservation of the distal end means it is not possible to observe the articulation for the astragalus. The lateral surface is mostly plane, and the posterior margin is practically straight, while the anterior margin is slightly concave ( Fig. 9D 1 ). The cnemial crest, although incomplete, is poorly developed compared with Neuquensaurus robustus ( Otero 2010) .

Titanosauria gen. et sp. indet. 2

Fig. 10 .

Material.— Three caudal vertebrae, MPCA−Pv 88/B, MPCAPv 88/C, and MPCA−Pv 88/D; right humerus, MPCA−Pv 88/ A. The last was found 2.5 m from the three vertebrae, so we interpret all these bones as belonging to a single specimen. All from Salitral Moreno locality, Rio Negro, Argentina, Campanian– Maastrichtian, Upper Cretaceous .

Description

Caudal vertebrae.—The two anterior (MPCA−Pv 88/B, MPCA−Pv 88/C) and one mid caudal vertebrae (MPCA−Pv 88/D) are short, slightly procoelous, with with wide articular surfaces ( Fig. 10A 1 , SOM 4). The lateral faces are anteroposteriorly concave, and the flat ventral surface is pierced by numerous foramina. The neural arch, although and posterior articulations, so the lateral faces of the centra are anteroposteriorly concave. The ventral surface of the centrum is plane. The most distinctive feature is the morphology of the posterior articulation, which is transversely wide, dorsoventrally compressed, as is the whole vertebra, and posteriorly extended forming a pointing protuberance. The vertebra is camellate.

These vertebrae were referred by Salgado and Azpilicueta (2000) to Rocasaurus muniozi . However, the general mornot well preserved, is low and transversely wide, with diapophyses wide and short and that become slender toward their distal ends.

Humerus.—The right humerus (MPCA−Pv 88/A) has a proximal expansion 12% greater than the distal ( Fig. 10B ). In anterior view, the lateral margin of the bone is slightly concave, while the medial margin is straight. The deltopectoral crest, although incomplete, is not much developed, but it does extend to the mid−length of the bone, as in Aeolosaurus and different from Neuquensaurus australis . The minimum diameter is at mid−shaft. The radial epicondyle seems to be larger than the ulnar epicondyle, as in all titanosaurs. The robustness index of this humerus is 0.16 (see SOM 4), slightly less than for the humerus of Aeolosaurus .

Titanosauria gen. et sp. indet. 3

Fig. 11 .

Material.—Three distal caudal vertebrae, MPCA−Pv 52, MPCA−Pv 53, and MPCA−Pv 55 from Salitral Moreno locality, Rio Negro, Argentina, Campanian–Maastrichtian, Upper Cretaceous.

Description.—These three small, dorsoventrally compressed caudal centra ( Fig. 11 ) have their widest points at the anterior

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phology, and, particularly, the morphology of the posterior articular surfaces, is notably different from the distalmost caudal vertebrae of this species.

Titanosauria gen. et sp. indet. 4

Fig. 12 .

Material.—Six caudal vertebrae, MPCA−Pv 861 to 866 from Salitral Moreno locality, Rio Negro, Argentina, Campanian– Maastrichtian, Upper Cretaceous.

Description.—These caudal vertebrae include two anterior−mid, one mid, and three mid−posterior elements ( Fig. 12 , SOM 5). All are markedly procoelous, and their most distinctive character is the pointing posterior condyle, much like the previous morphotype. There is a bony cingulum bordering the condyle, which extends as two lobes to the articulations for the haemapophyses.

In all the vertebrae the neural canal is very wide; the distinctive character of these bones is their flat neural canal divided by a small septum, throughout its entire base.

In lateral view ( Fig. 12A 1 , C, D), the vertebral centra are quadrangular. At least the centra of MPCA−Pv 861 and MPCA−Pv 864 are compact, massive, without inner spaces (which can be observed through a broken area); this is a clear difference from the condition in other titanosaurs recorded in the area, such as Rocasaurus . Numerous lanceolated foramina pierce all the surface of the centrum, both ventral and the lateral surfaces. The number of foramina increases to the distalmost caudals. The lateral faces are anteroposteriorly concave and their ventral face is plane. The articulations for the haemapophyses are well developed. Although the neural spine of MPCA−Pv 861 and MPCA−Pv 862 is badly preserved, these probably reached the posterior border of the centrum.

Figures

Fig. 5. Femora of titanosaurs from Salitral Moreno locality, Rio Negro, Argentina, Campanian–Maastrichtian, Upper Cretaceous, showing the greater trochanter angle. A. Aeolosaurus sp. (MPCA−Pv 27174). B. Rocasaurus muniozi Salgado and Azpilicueta, 2000 (MPCA−Pv 46/6). C. Titanosaurus sp. (MPCA−Pv 33/2).

Fig. 6. Titanosaur sauropod Rocasaurus muniozi Salgado and Azpilicueta, 2000 from Salitral Moreno locality, Rio Negro, Argentina, Campanian–Maastrichtian, Upper Cretaceous. Cervical vertebrae MPCA−Pv 859 (A), MPCA−Pv 860 (B), and MPCA−Pv 858 (C) in lateral views.

Fig. 7. Titanosaur sauropod Rocasaurus muniozi Salgado and Azpilicueta, 2000, vertebrae from Salitral Moreno locality, Rio Negro, Argentina, Campanian–Maastrichtian, Upper Cretaceous. A. Dorsal vertebra (MPCA−Pv 46/8), in lateral (A1) and dorsal (A2) views. B. Dorsal neural arch of the 8th? (MPCA−Pv 46/4), in lateral view. C. Dorsal neural arch of the 10th? (MPCA−Pv 46/5), in posterior view. D. Anterior caudal vertebra (MPCA−Pv 57), in lateral view. E. Mid caudal vertebra (MPCA−Pv 58), in lateral (E1) and ventral (E2) views. F. Anterior caudal vertebra (MPCA−Pv 47), in ventral view. G. Posterior caudal vertebra (MPCA−Pv 46/10), in lateral view. H. Distal posterior caudal vertebra (MPCA−Pv 56), in dorsal view.

Fig. 8. Titanosaur sauropod Rocasaurus muniozi Salgado and Azpilicueta, 2000 from Salitral Moreno locality, Rio Negro, Argentina, Campanian–Maastrichtian, Upper Cretaceous. A. Left femur (MPCA−Pv 46/16), in posterior (A1) and distal (A2) views. B. Left ilium (MPCA−Pv 46/12), in lateral view. C. Left ischium (MPCA−Pv 46/11), in lateral view. D. Left pubis (MPCA−Pv 46/15), in lateral view.

Fig. 2. Titanosaur sauropod Aeolosaurus sp. (MPCA−Pv 27174) from Salitral Moreno locality, Rio Negro, Argentina, Campanian–Maastrichtian, Upper Cretaceous. A. First? anterior caudal vertebrae, in right lateral view. B. Third? anterior caudal vertebrate, in right lateral view. C. Fifth? anterior caudal vertebrae, in left lateral view. D. Tenth? anterior caudal vertebrae, in left lateral view. E. Haemal arch, in anterior view.

Fig. 1. Site map showing the geographical location of Salitral Moreno, where specimens of titanosaurs were collected.

Fig. 9. Titanosauria gen. et sp. indet. 1 from Salitral Moreno locality, Rio Negro, Argentina, Campanian–Maastrichtian, Upper Cretaceous. A. Right femur (MPCA−Pv 33/2), in posterior (A1) and distal (A2) views. B. Mid caudal vertebrae (MPCA−Pv 867), in lateral view. C. Right humerus (MPCA−Pv 33), in anterior view. D. Right tibia (MPCA−Pv 33/1), in lateral (D1), proximal (D2), and medial (D3) views. The arrow shows a sharp lateral ridge.

Fig.10. Titanosauria gen. et sp. indet. 2. from Salitral Moreno locality, Rio Negro, Argentina, Campanian–Maastrichtian, Upper Cretaceous. A. Caudal vertebrae (MPCA−Pv 88/B), in posterior (A1) and anterior (A2) views. B. Right humerus (MPCA−Pv 88/A), in anterior view.

Fig. 11. Titanosauria gen. et sp. indet. 3, distal caudal vertebrae from Salitral Moreno locality, Rio Negro, Argentina, Campanian–Maastrichtian, Upper Cretaceous. A. MPCA−Pv 52, in ventral (A1) and lateral (A2) views. B. MPCA−Pv 53, in ventral (B1) and posterior (B2) views.

Fig. 12. Titanosauria gen. et sp. indet. 4 from Salitral Moreno locality, Rio Negro, Argentina, Campanian–Maastrichtian, Upper Cretaceous. A. Mid−posterior caudal vertebra (MPCA−Pv 862), in lateral (A1), ventral (A2), and posterior (A3) views. B. Mid−posterior caudal vertebra (MPCA−Pv 861), in dorsal view. C. Anterior−mid caudal vertebra (MPCA−Pv 863), in lateral view. D. Mid caudal vertebra (MPCA−Pv 864), in lateral view.