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Juárez Valieri et al.: A new hadrosauroidRev. from Mus. Patagonia Argentino Cienc. Nat., n.s.217 12(2): 217-231, 2010 Buenos Aires, ISSN 1514-5158

A new hadrosauroid (Dinosauria: Ornithopoda) from the Allen Formation (Late Cretaceous) of Patagonia, Argentina

Rubén D. JUÁREZ VALIERI1, José A. HARO2, Lucas E. FIORELLI3 & Jorge O. CALVO4

1 Centro Paleontológico Lago Barreales (CePaLB). Universidad Nacional del Comahue. Ruta Provincial N° 51, km 65. (8300). Neuquén, Argentina. [email protected].� 2Centro de Investigaciones Paleobiológicas (CIPAL). Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba. Velez Sarfield 299 (5000). Córdoba, Argentina. [email protected]. 3Centro Regional de Investigaciones Científica y Transferencia Tecnológica (CRILAR). Entre Ríos y Mendoza. (5301). Anillaco, La Rioja, Argentina. lfiorelli@ crilar-conicet.com.ar. 4Centro Paleontológico Lago Barreales (CePaLB). Universidad Nacional del Comahue. Ruta Provincial N° 51, km 65. (8300).�� Neuquén, Argentina. jorgecalvo@�p��royectodino.com.ar

Abstract: ��A new ��hadrosauroid taxon from the Late Cretaceous Allen Formation is erected, on the basis of abundant cranial and postcranial material from the Salitral Moreno locality of the Rio Negro Province, Argentina. The new taxon is here named as Willinakaqe salitralensis gen. et sp. nov., which is characterized by having an autapomor- phous premaxilla with a long and convex rostrolateral surface rostral to the narial fossa and associated postcrania developing an unique character combination, including: dorsal vertebrae with a shallow fossa upon the base of the transverse processes; sacral and proximal caudal neural spines more than three times the height of the centrum; distal region of the postacetabular process of ilium ventrally deflected, among others. This new hadrosauroid closely resembles Secernosaurus koerneri, the other valid hadrosauroid species from South America, based in several synapomorphies, as: angle greater than 115° between the lateral margin of the facet for scapular articulation and the glenoid in the coracoid; supra-acetabular process of the ilium asymmetrical, caudodorsal margin of ilium with a well-defined ridge continuous with the dorsal margin of the proximal region of the postacetabular process. Moreover, previous records of Lambeosaurinae from the Late Cretaceous of South America are referred to W. salitralensis, and thus, the presence of lambeosaurines in this continent is here rejected. Accordingly, Willinakaqe salitralensis gen. et sp. nov. is currently the only hadrosauroid species reported from the Allen Formation.

Key words: Hadrosauroidea, morphology, palaeobiogeography, Late Cretaceous, South America.

Resumen: Se erige un nuevo taxón de hadrosauroideo del Cretácico Superior de la Formación Allen, en base a abundante material craneal y postcraneal de la localidad de Salitral Moreno, en la Provincia de Río Negro, Ar- gentina. El nuevo taxón es denominado Willinakaqe salitralensis gen. et sp. nov., y se caracteriza por tener un premaxilar autapomórfico con una superficie rostrolateral alargada y convexa rostral a la fosa narial y postcráneos asociados con una combinación de caracteres únicos, que incluye: vértebras dorsales con una fosa poco profunda en la base de los procesos transversos, espinas neurales sacras y caudales proximales más de tres veces más altas que el centro; región distal del proceso postacetabular del ilion desviada ventralmente, entre otros. Este nuevo hadrosauroideo es muy similar a Secernosaurus koerneri, la otra especie válida de hadrosauroideo de América del Sur, con el que comparte varias sinapomorfías, como: ángulo mayor que 115 ° entre el borde lateral de la faceta articular escapular y la superficie glenoidea en el coracoides, proceso supra-acetabular del ilion asimétrico, margen caudodorsal del ilion con una cresta bien definida continua con el margen dorsal de la región proximal del proceso postacetabular. Los registros asignados anteriormente a Lambeosaurinae del Cretácico Tardío de América del Sur son referidos a Willinakaqe salitralensis gen. et sp. nov., y por lo tanto, se rechaza la presencia de lambeosaurinos en este continente. En consecuencia, Willinakaqe salitralensis gen. et sp. nov. es actualmente la única especie de hadrosauroideo reportada en la Formación Allen.

Palabras clave: Hadrosauroidea, morfología, paleobiogeografía, Cretácico Superior, América del Sur. ______

INTRODUCTION koerneri, which is based on an incomplete postcranial skeleton recovered close to the Río Chico Hadrosauroids are known from the Southern locality in the Chubut province, central Patagonia, Hemisphere ever since Casamiquela (1964) de- Argentina (Brett-Surman, 1979). Since its original scribed the first materials. The first named had- description, Secernosaurus was considered as a rosauroid from South America was Secernosaurus problematic taxon because some bones present a 218 Revista del Museo Argentino de Ciencias Naturales, n. s. 12 (2), 2010

Fig. 1. Map indicating the northern Patagonian localities from which the hadrosauroid fossils here studied have been recovered (indicated as stars). high degree of deformation; consequently, several thus providing additional evidence for an inter- anatomical characters �reviously employed to American dispersal event at Campanian times assign the species as a basal hadrosauroid are (Bonaparte, 1996). product of taphonomic processes (Brett-Surman, However, �osterior authors suggested that 1979; Bonaparte et al., 1984; Bonaparte, 1996). Kritosaurus australis may not belong in fact to Additionally, the �recise stratigraphical �rove- Kritosaurus, and the species as considered as nance of Secernosaurus is unknown, decreasing its “K.” australis (Horner et al., 2004). Recent revi- biostratigraphical and biogeographical relevance sions of the material assigned to “Kritosaurus” (Bonaparte, 1996; Prieto-Márquez & Salinas, australis led to the proposal that this purported 2010). The second species of Hadrosauroidea species corresponds to the genus Secernosaurus, proposed and described for Cretaceous beds in i.e. S. australis (Wagner, 2001), and more recently, South America is Kritosaurus australis, coming to the hypothesis of its synonymy with the type from the Los Alamitos ranch, Río Negro province, species, Secernosaurus koerneri (Prieto-Már- northeastern Patagonia (Bonaparte et al., 1984). quez & Salinas, 2010). In this way, Kritosaurus This taxon is represented by several specimens, australis is here considered as a junior synonym comprising cranial and �ostcranial remains of of Secernosaurus koerneri, following the latter partial skeletons, hich ere recovered in the suggestion. middle levels of Los Alamitos Formation, which In the present work, we describe new hadro- is late Campanian or early Maastrichtian in age. sauroid materials from the Salitral Moreno area, K. australis was the most complete hadrosauroid coming from the same locality where the remains species hitherto described for South America, of the purported lambeosaurine were recovered and its assignment to the North American genus (Juárez Valieri et al., 2007). Based on these speci- Kritosaurus was considered as a strong landmark mens, as well as Powell’s (1987) “lambeosaurine”, in order to determine the provenance and time and further material previously reported from the of arrival of this group of dinosaurs to South Allen Formation (González Riga & Casadío, 2000), America (Bonaparte & Rougier, 1987; Bonaparte, we erect a new hadrosauroid taxon. 1996). A third unnamed hadrosauroid taxon was thought to be present in South America (Powell, MATERIALS AND METHODS 1987), described on the basis of an incomplete postcranial skeleton from the lower section of the We follow the nomenclature and definition Allen Formation, Salitral Moreno area, northern of the clades among Hadrosauroidea described Patagonia. This specimen as considered as by Prieto-Márquez (2010), and the suggestions belonging to the Lambeosaurinae, contrasting of the second edition of the compendium “The with the “hadrosaurine” assignment proposed for Dinosauria” by Weishampel et al. (2004) regarding Secernosaurus koerneri and Kritosaurus australis, anatomical orientations. Juárez Valieri et al.: A new hadrosauroid from Patagonia 219

Anatomical abbreviations Holotype. MPCA-Pv SM 8, a right premax- ac: acetabulum, aig: cranial intercondylar illa. groove, as: alveolar sulci, cf: coracoid foramen, cp: coronoid process, d: dentary, dc: deltopectoral Paratypes. MPCA-Pv SM 2, partial skeleton crest, dpp: dorsal process of predentary, ds: distal including: dorsal, sacral and caudal vertebrae, shaft, en: external naris, er: edentulous region, f: ossified ligaments, haemapophyses, ribs, left frontal, fo: foramina, gl: glenoid, ilr: iliac ramus, scapula, right ilium and ischium, femora, tibiae, ip: iliac peduncle, is: ischial shaft, mdp: maxillary fibulae, calcanea and distal tarsals, and left astra- dorsal process, mf: maxillary foramen, mc: medial galus and foot; MPCA-Pv SM 12, left maxillae with carina (=primary carina), nc: neural channel, nf: teeth; MPCA-Pv SM 03, right lower jaw, including nutrient foramen, ns: neural spine, �: �arietal, dentary, surangular, angular, and teeth; MPCA-Pv pa: papilla, pb: pubic bar, pd: predentary, pdf: pre- SM 27, left scapula; MPCA-Pv SM 29, right cora- dentary facet, po: postorbital, pop: postacetabular coid; MPCA-Pv SM 32, left sternum; MPCA-Pv process, pp: prepubis, pr: prezigapophysis , pra: SM 33, left humerus; MPCA-Pv SM 39, left ilium, pubic ramus, �rp: �reacetabular �rocess, �z: MPCA-Pv SM 41, right incomplete pubis. postzygapophysis, rc: radial condyle, sa: surangular, sb: scapular blade, sf: splenial facet, sp: Referred materials. MPCA-Pv SM 10, left supraacetabular process, sq: squamosal, stf: su- maxilla; MPCA-Pv SM 4 to 6, left and right dentaries; pratemporal fenestra, sy: mandibular symphysis, MPCA-Pv SM 7 and 9, isolated teeth; MPCA-Pv SM th: teeth, tp: transverse process, uc: ulnar condyle, 11, 13 and 14, cervical vertebrae; MPCA-Pv SM 15 vpc: ventral process of coracoid. to 22, dorsal vertebrae; MPCA-Pv 23 to 25, caudal vertebrae; MPCA-Pv SM 26, dorsal rib; MPCA-Pv Institutional abbreviations SM 28, scapula; MPCA-Pv SM 30 and 31, coracoids; MPHN-Pv: Museo Provincial de Historia MPCA-Pv SM 34 to 38, humeri; MPCA-Pv SM 40, Natural, Santa Rosa, La Pampa, Argentina, Colec- ilium; MPCA-Pv SM 42 to 44, femora; MPCA-Pv SM ción de Paleontología de Vertebrados. 45 and 46, tibiae; MPCA-Pv SM 47, fibula; MPCA-PV MPCA-Pv SM: Museo Provincial Carlos 48 to 51, metatarsals; MPCA-PV 52 to 55, phalanges Ameghino, Cipolletti, Río Negro, Argentina, and unguals; MPHN-Pv 01, partial single skeleton in- Paleontología de Vertebrados, Colección Salitral cluding cervical, dorsal, sacral, and caudal vertebrae, Moreno. dorsal ribs, left scapula and coracoid, right femur, and two pedal phalanges, one of which is an ungual. SYSTEMATICS Diagnosis. Willinakaqe salitralensis gen. Ornithopoda Marsh 1881 nov. et sp. nov. is diagnosed by the following com- Ankylopollexia Sereno 1986 bination of characters among Hadrosauroidea: Hadrosauroidea Sereno 1986 premaxilla ith a long and convex rostrolateral Saurolophidae (Brown 1914) surface rostral to the narial fossa (autapomorphy); narial fossa shallow, with presence of a premaxillary Willinakaqe gen. nov. foramen; caudodorsal and caudolateral processes of the premaxilla widely divergent, premaxillary Etymology. The generic name is formed denticles not well developed; dorsal vertebrae with by the combination of the following ords of a shallow fossa located on the lateral surface of the the Mapuche language: willi meaning South, neural arch, upon the base of the transverse process iná meaning mimic and kaqe meaning duck; (autapomorphy); eight sacral vertebrae in adults, the name thus meaning “the duck-mimic of the the first with a ventral keel; high neural spines in South”. sacral and proximal caudals, more than three times the height of the centrum; caudal neural spines Type species. The type and only known species showing a progressive distal expansion; dorsal bor- of the genus is Willinakaqe salitralensis sp. nov. der of the proximal section of the scapula straight; distal region of the postacetabular process of ilium Diagnosis. As for the type and only species ventrally deflected (autapomorphy); femur without (monotypic genus). enclosed cranial intercondylar groove.

Willinakaqe salitralensis sp. nov. Occurrence. The materials corresponding to the holotype, �aratypes and most referred Etymology. The name salitralensis refers specimens of Willinakaqe salitralensis gen. nov. to the Salitral Moreno locality, here the first et sp. nov., housed at the Museo Provincial Carlos remains were recovered. Ameghino, come from the southeastern region of 220 Revista del Museo Argentino de Ciencias Naturales, n. s. 12 (2), 2010

Fig. 2. Restoration of the skeleton of Willinakaqe salitralensis gen. et sp. nov. Preserved bones are white.

the Salitral Moreno locality, in the north of the Description. In the present study we describe Río Negro province, 20 km. south of the General the elements that present useful morphological Roca locality, Argentina (Fig. 1). These remains traits for the taxonomical and phylogenetic analy- were recovered in a single bone-bed together with sis of the species. Additional morphological traits sauropod and ankylosaurian remains (Salgado & of this taxon ere codified by Prieto-Márquez Azpilicueta, 2000; Coria & Salgado, 2001). The (2010) for inclusion in their data matrix where it hadrosauroid remains are the most abundant in is informally named as “Salitral Moreno OTU” the assemblage, representing individuals of dif- and are briefly treated in the Discussion section. ferent ontogenetic stages, ith estimated total A more detailed anatomical description of Will- lengths ranging between one and 9 meters. The inakaqe salitralensis gen. nov. et sp. nov. will be larger specimens, as MPCA-Pv SM 2, display com- published elsewhere. pletely fused centra and neural arches in dorsal vertebrae and here are thus considered as presum- Cranial skeleton able adult individuals (Irmis, 2007��; Dalla Vecchia, Premaxilla. This bone (MPCA-Pv SM 8; Fig. 2009).�� Most of the �reserved�� cranial, axial and 3A, B) is the most distinctive element available appendicular bones are represented by multiple el- for Willinakaqe salitralensis gen. et sp. nov. It ements, including partially articulated and closely displays a suite of plesiomorphic and derived char- associated pieces. Because all of them correspond acter states, whose combination is unique among to a single morphotype, the contention that these Hadrosauroidea. Accordingly, this element as belong to a single taxon in the site is supported. designed as the holotype of the new taxon. The The referred material housed at the Museo Pro- premaxilla is almost complete, lacking the vent- vincial de Historia Natural de La Pampa, came rolateral surface of the corner of the oral border from the Islas Malvinas locality, southwest of La and the caudal extremities of the caudodorsal and Pampa province (Fig. 1). This specimen, MPHN- caudolateral processes. The denticles are poorly Pv 01, is considered as belonging to Willinake preserved in the available material and it is not salitralensis gen. et sp. nov. because it preserves possible to assert if they were as prominent as in the same morphological traits, including these basal hadrosauroids, such as Telmatosaurus trans- considered here as of diagnostic value in all the sylvanicus (Weishampel et al., 1993). Although a elements comparable with those from the type lo- slight groove separates the denticle layer from the cality (see below). Both localities, Salitral Moreno remaining premaxillary ventral surface, an inner and Islas Malvinas, correspond to the lower sec- palatal rim distinct from the denticle layer is not tion of the Allen Formation (Malargüe Group), of evident, as occurs in other saurolophids such as late Campanian - early Maastrichtian age (Andreis Prosaurolophus (Horner, 1992). In dorsal view, et al., 1974; Casadío, 1994). the oral and lateral margins are rounded and Juárez Valieri et al.: A new hadrosauroid from Patagonia 221

Fig. 3. Willinakaqe salitralensis gen. et sp. nov., cranial bones. A) and B) premaxilla of holotype specimen (MPCA- Pv SM 8) in A) dorsal and B) ventral view. C) to E) Maxilla of specimen (MPCA-Pv SM 12 in C) lateral, D) medial, and E) ventral views. Abbreviations in text.

poorly transversely expanded. This morphology salitralensis gen et sp. nov. (if not present also in is also present in the primitive forms Eolambia near relatives such as Secernosaurus koerneri). A caroljonesa, Bactrosaurus johnsoni, and Telmato- single foramen is present at the rostroventral end saurus transsylvanicus, and is not so transversely of the internal circumnarial fossa, which pierces expanded as in the saurolophines, nor with the the premaxillary body and opens at the ventral deflected rostroventral corner �resent in the surface of the bone. This character is not currently lambeosaurines (Prieto Márquez et al., 2006). The known in any lambeosaurine, and is considered as area comprised between the oral margin and the a synapomorphy of the Saurolophinae (Horner et rostroventral border of the circumnarial fossa is al., 2004; Prieto-Márquez, 2010). Two additional noticeably more extense than in basal forms like foramina are present on the rostral region of the Eolambia, Telmatosaurus, or the lambeosaurines dorsal surface of the �remaxilla. At the caudal (Ostrom, 1961; Weishampel et al., 1993; Head, region of the premaxilla, the preserved portions 2001). This area may be considered homologous of the caudodorsal and caudolateral processes do with the area occupied by the external circum- not present evidence of enclosing the narial pas- narial fossa of the saurolophines, but Willinakaqe sage, as occurs in lambeosaurines. Nevertheless, gen. nov. does not present the depression, nor the more complete skulls are necessary to confirm the invaginated oral or lateral margins in this region, latter assumption. unlike the condition seen in Saurolophinae (Had- Maxilla. Two almost complete maxillae rosaurinae sensu Horner et al., 2004), and is con- were recovered from the Salitral Moreno local- sidered as a possible autapomorphy of Willinakaqe ity (MPCA-Pv SM 10 and 12, Fig. 3C-E); the 222 Revista del Museo Argentino de Ciencias Naturales, n. s. 12 (2), 2010

Fig. 4. Willinakaqe salitralensis gen. et sp. nov., lower jaw elements. A) lateral view of left dentary of specimen MPCA-Pv SM 6; B) medial view of the same element; C) closeup of B) to show medial surface of rostral tooth; C) lateral surface of right dentary of specimen MPCA-Pv SM 3. Abbreviations�� in text.

first corresponding possibly to an adult and the the derived condition present in Lambeosaurinae, second to a subadult individual. This element is in which is dorsoventrally well-developed. In lat- rostrocaudally elongated, ith a rostrocaudally eral view, a maxillary foramen is located below the symmetrical morphology. The dorsal process of the base of the dorsal process and a second foramen is maxilla is only slightly elevated, contrasting with observed more caudally, with a ventral orientation. Juárez Valieri et al.: A new hadrosauroid from Patagonia 223

Fig. 5. Willinakaqe salitralensis gen. et sp. nov.; vertebrae. A-D) cranial dorsals, MPCA-Pv SM 15 and 16, in lateral (A and B) and caudal (C and D) views; E-H) caudal dorsals, MPCA-Pv SM 20-22, in cranial (E), caudal (F and G) and left lateral (H) views; I-K) proximal caudals, MPCA-Pv SM 23 and 24, in caudal (I), cranial (J), and left lateral (K) views. Abbreviations in text.

In medial view, the maxilla displays a continuous et sp. nov. displays a suite of characters proper of series of nutrient foramina. In general aspect, the the derived hadrosauroids, but not apomorphic maxilla of Willinakaqe gen. nov. is reminiscent to traits of Saurolophidae or any of their nested that described for Bactrosaurus johnsoni, Aralo- groups. The rostral region lacks an elongate saurus tuberiferus, and Pararhabdodon isonense symphysis, and shows a short diastema as present (Godefroit et al., 1998, 2004; Prieto-Márquez et in basal hadrosauroids and some saurolophines al., 2006). and lambeosaurines (Horner et al., 2004). In Dentary. Two almost complete and two par- lateral view, the ventral surface of dentary is tially preserved dentaries are present among the weakly concave and subparallel with the straight Salitral Moreno material (MPCA-Pv SM 3 to 6; dorsal margin at its mid-length. The predentary Fig. 4). This material includes elements of variable facet is almost vertical in lateral view. A series of size. The dentary of Willinakaqe salitralensis gen. foramina form a continuous line at mid-height 224 Revista del Museo Argentino de Ciencias Naturales, n. s. 12 (2), 2010

Fig. 6. Willinakaqe salitralensis gen. et sp. nov. A and B) scapula of specimen MPCA-Pv SM 2 in A) lateral and B) medial views. C and D) sternal plate of specimen MPCA-Pv SM in C) dorsal and D) ventral views.

on the lateral surface of the dentary. The coronoid Axial skeleton process is subvertical, with a rostrocaudal expansion Cervical vertebrae. The best preserved cer- at its distal end, as usual in saurolophines and some vical vertebrae are those of MPHN-Pv 01, which lambeosaurines (Horner et al., 2004). In medial view, have been previously described and illustrated by the dentary presents a series of subvertical parallel González Riga & Casadío (2000, Fig. 4A-C). Ad- alveolar sulci. In all the preserved dentaries there are ditional material came from the Salitral Moreno no more than thirty alveoli. The general morphology locality (MPCA-Pv SM 11, 13 and 14). The cervical of the dentary of Willinakaqe salitralensis gen. et sp. vertebrae of Willinakaqe salitralensis gen. et sp. nov. closely resembles that of Secernosaurus koerneri nov. displays the same basic morphology present in (Prieto-Márquez & Salinas, 2010). Telmatosaurus and more derived hadrosauroids. Teeth. Multiple teeth of Willinakaqe gen. nov. As originally noted by González Riga & Casadío have been recovered adhered to some maxillae (2000), the cervical vertebrae of this taxon can (MPCA-Pv 10 and 12) and dentaries (MPCA-Pv be distinguished from those of Secernosaurus SM 3 and 4, Fig. 4B, C). Isolated dental elements on the basis of the angle of divergence between are also present (MPCA-Pv SM 7 and 9), which are the �ostzygapophyses, hich is greater in the tentatively associated to Willinakaqe salitralensis latter taxon, and this represents one of the key gen. et sp. nov. because of their close association characters allowing the association of the Salitral to the remaining cranial and postcranial material�, Moreno and the Islas Malvinas specimens in a and close similarity to the teeth preserved in artic- single taxon. ulation with bones. The dentary teeth are disposed Dorsal vertebrae. Isolated dorsal vertebrae in a dental battery with three pieces per alveolus. comprising different regions of the column are In the most rostral dentary teeth (MPCA-Pv SM 4, present (MPCA-Pv SM 15 to 22, MPHN-Pv 01, Fig. 4C), there is a complete absence of denticula- Fig. 5A-H; González Riga & Casadío, 2000, Fig. tions. These rostral dentary teeth present a single 4D), as evidenced by the different angles between central carina and are mesiodistally symmetrical. the transverse processes and neural spines and the In opposition, the teeth located in the middle and size and orientation of the neural spines, which caudal section of the dental battery (MPCA-Pv SM increases along the sequence and gets a more ver- 3) present small denticles on the distal borders. tical orientation. Most of these vertebrae belong The morphology of these caudal dentary teeth is to juvenile individuals. As noted by González Riga reminiscent to those found in the hadrosauroids & Casadío (2000) for the Islas Malvinas material, from Antarctica described by Case et al. (2000) and although their morphology is mostly usual for some saurolophines (Horner et al., 2004). saurolophids, these vertebrae are different to Juárez Valieri et al.: A new hadrosauroid from Patagonia 225

Fig. 7. Willinakaqe salitralensis gen. et sp. nov. Right humerus of specimen MPCA-Pv SM 33 in A) caudolateral and B) craniomedial views. C) Left humerus of specimen 38 in craniomedial view. Abbreviations in text.

those of Secernosaurus in the presence of a weak K), are considered here as proximal caudals due cavity located in the lateral face of the neural arc, to the dorsal �rojection of their neural spines, upon the base of the transverse process (Fig. 5H). and the similar ratio between the centrum and This trait is here considered as an autapomorphy the neural spine heights. The caudal vertebrae of Willinakaqe salitralensis gen. et sp. nov. recovered in the Islas Malvinas locality (González Sacral and caudal vertebrae. An articu- Riga & Casadío, 2000) preserve incomplete neu- lated series of twenty five proximal and medial ral spines, but the morphology of the centrum caudal vertebrae, continuing the complete sacral and neural arch is identical to that of the other sequence, is present in the specimen MPCA-Pv SM elements belonging to Willinakaqe gen. nov (see 2 (Powell 1987, Fig. 2). Isolated caudals are also below). Another character also described by Powell present in the Salitral Moreno (MPCA-Pv SM 23 (1987) and present in all the available elements to 25) and the Islas Malvinas material (MPHN- is the progressive distal expansion of the neural Pv 01, González Riga & Casadío 2000, Fig. 4F). spines, in both the proximodistal (along the axis of The sacrum of an adult individual of Willinakaqe the tail) and transverse planes. A slight proximo- gen. nov., MPCN-Pv SM 2, is composed of eight distal (along the axis of the tail) constriction in the fused vertebrae, as in Pararhabdodon isonense caudals at the base of the neural arch was observed (Prieto-Márquez et al., 2006). This sacral number by González Riga & Casadío (2000, Fig. 4F) in the is low in comparison ith most saurolophids, Islas Malvinas material, and the same morphology which present more than nine sacral vertebrae in is present in the caudal vertebrae from Salitral adults (Horner et al., 2004). In Willinakaqe gen. Moreno. These authors also noted the distinctive nov., the first sacral vertebra presents a ventral location of the postzygapophysis, situated dorsal keel, but it is not present in the following sacrals. to the prezygaphophysis, a condition also seen in All the sacral vertebrae, as well as the proximal all known specimens of Willinakaqe gen. nov. By caudal vertebrae, display dorsoventrally well-de- contrast, Secernosaurus koerneri �resents both veloped neural spines, with a height comprising zygaphophyses at almost the same level. The 4.8 times the centrum height in the first caudal centra of the proximal caudal vertebrae are sub- of the articulated sequence (Powell, 1987, Figs 2, circular in contour in proximal view, with a convex 3). Additional isolated vertebrae from the Salitral ventral margin. Mid- and distal caudal vertebrae Moreno locality, MPCA-Pv SM 23 and 24 (Fig. 5I- show a sagittal sulcus at their ventral surface. 226 Revista del Museo Argentino de Ciencias Naturales, n. s. 12 (2), 2010

Fig. 8. Willinakaqe salitralensis gen. et sp. nov. Right ilium of specimen MPCA-Pv SM 39 in A) medial, B) lateral, and C) dorsal views. Abbreviations in text.

Appendicular skeleton salitralensis gen. et sp. nov. and Secernosaurus Scapula. This bone is represented by four koerneri is �resent in the dorsal border of the specimens, MPCA-Pv SM 2, 27, 28 and MPHN-Pv proximal region, hich in the former is almost 01, the second of them being the most completely straight, as previously noted for the Islas Malvinas preserved (Fig. 6A, B). The entire morphology of material by González Riga & Casadío (2000). the bone can be assessed on the basis of the cur- Coracoid. Four coracoids are �reserved: rently available material. As mentioned by Powell MPCA-Pv SM 29, which is completely preserved, (1987), the scapular blade is slightly distally MPCA-Pv SM 30 and 31, which preserve the entire expanded in adult and subadult individuals, as bone except for the coracoidal hook, and MPHN- in Secernosaurus koerneri and non-saurolophid Pv 01, which comprises the cranial region of the taxa, such as Bactrosaurus and Telmatosaurus bone. The morphology of the coracoid is closely (Godefroit et al., 1998; Weishampel et al., 1993). similar to that found in Secernosaurus koerneri, The distal border of the scapula is perpendicular with the coracoid foramen placed in the caudal to the shaft. In the �roximal end, the scapula region, completely surrounded by bone, and presents a large and prominent acromial bridge. presenting a craniocaudally elongate oval shape. A difference between the scapulae of Willinakaqe Bonaparte & Rougier (1987) considered this mor- Juárez Valieri et al.: A new hadrosauroid from Patagonia 227

Fig. 9. Willinakaqe salitralensis gen. et sp. nov. Right prepubic process of specimen MPCA-Pv SM 41 in A) lateral and B) medial views. Left femur of specimen MPCA-Pv SM 42 in C) cranial and D) distal views. Abbreviations in text. phology as diagnostic of “Kritosaurus” australis. of Secernosaurus koerneri (Bonaparte & Rougier, The coracoid presents a convex craniodorsal cor- 1987; Prieto-Márquez & Salinas, 2010). ner. Ventral to this corner there is a fossa on the Humerus. Six humeri of Willinakaqe salit- craniolateral border at mid-height of the bone. ralensis gen. et sp. nov. (MPCA-Pv SM 33 to 38) The coracoid is distally expanded and �resents were recovered in the Salitral Moreno locality, a strongly developed ventral coracoidal hook. representing different ontogenetic stages ith This hook is similar in shape to that present in sizes ranging between twelve and fifty five cen- Secernosaurus, Telmatosaurus and Gryposaurus, timeters in proximodistal length. The most re- more distally �rominent than in Bactrosaurus, markable feature is the presence of a deltopecto- but not so developed as in Brachylophosaurus ral crest which is well-developed in proximodistal (Bonaparte & Rougier, 1987; Prieto-Márquez and mediolateral senses (Fig. 7), which resembles & Salinas 2010; Weishampel et al., 1993, 2004; that seen in Tanius, Pararhabdodon,and the Godefroit et al., 1998). lambeosaurines, contrasting with the condition Sternum. An almost complete left sternal present in Telmatosaurus, Hadrosaurus, and plate is preserved (MPCA-Pv SM 32, Fig. 6C, D). It the saurolophines. However, as observed by presents a long and slender diaphysis, more elon- Prieto-Márquez et al. (2006) the �resence of a gated than that usually observed in saurolophids. prominent deltopectoral crest is a homoplastic At the proximal region, it expands up to the tip. character and not necessarily a lambeosaurine The general shape is strongly reminiscent to that synapomorphy. 228 Revista del Museo Argentino de Ciencias Naturales, n. s. 12 (2), 2010

Ilium. Three ilia have been recovered, MPCA- DISCUSSION AND CONCLUSIONS Pv SM 2, 39 and 40, of which the first two are almost complete. The general morphology of this Willinakaqe salitralensis gen. et sp. nov. and bone (Fig. 8) is comparable to those of derived Secernosaurus koerneri exhibit several anatomi- hadrosauroids, in the �resence of a deflection cal similarities, mainly symplesiomorphies, but on the dorsal surface and the occurrence of a several of these allow differentiating these South well-developed �ostacetabular �rocess. The su- American species from hadrosauroids less derived pracetabular process is wide and prominent, as than Telmatosaurus transsylvanicus or Tanius reported by Powell (1987) for MPCA-Pv SM 2, sinensis, and from the different saurolophine and and the distal rim slightly bows ventrolaterally. lambeosaurine subclades. Following to Prieto- This results in a dorsally convex and ventrally Márquez (2010), Willinakaqe salitralensis gen. et concave antitrochanter. The postacetabular proc- sp. nov. can be included in the Saurolophidae and ess of the ilium is wide and presents a distinctive more inclusive clades among Hadrosauroidea on caudoventral curvature at the distal region. The the basis of the following character states: location overall morphology of the ilium of Willinakaqe of the origin of the ventral deflection of the den- salitralensis gen. et sp. nov. more closely resembles tary near to the origin of the dental battery; bulg- that of Secernosaurus koerneri than that of other ing of the ventral lateral margin of the dentary hadrosauroids (see below). straight or slightly bowed rostral to the coronoid Ischium. A complete ischium is �reserved process; thick and dorsoventrally elongated ridge in MPCA-Pv SM 2, which was briefly described on the medial side of the coronoid process absent; by Powell (1987). The shaft is entirely straight, dentary lingual arching of the occlusal plane ab- and the distal end does not �resent a foot-like sent, with rostrocaudally straight occlusal plane; expansion in this adult individual, exhibiting the length of the ectopterygoid shelf relative to the same general morphology of Secernosaurus, but total rostrocaudal length of the alveolar margin contrasting with the condition present in Parar- of the maxilla greater than 0.35; development of habdodon and several saurolophids, which show the �ostzygapophyseal �roceses of cranial and a well developed distal foot in adult individuals middle cervical vertebrae three times or more (Horner et al., 2004; Guenther, 2009). longer than the breadth of the neural arch; length Pubis. An incomplete pubis comprising most of the deltopectoral crest of the humerus devel- of the prepubic blade is preserved (MPCA-Pv SM oped greater than 55 percent of the proximodistal 41, Fig. 9A, B). It bears a dorsoventrally convex length of the humerus; lateroventral expansion lateral surface and a planar medial one. The blade of the deltopectoral crest of the humerus well ex- presents its maximum dorsoventral expansion in panded; ventral margin of the deltopectoral crest the middle of the shaft. From this point, the dorsal extending abruptly from the humeral shaft to give and ventral borders converge cranially, resulting a distinct angular profile; ventral deflection of the in a non-parallel �attern, unlike the condition preacetabular process of the ilium with an angle present in Secernosurus and Gryposaurus (Prieto- of less than 150°; supraacetabular process cranio- Márquez, 2010: appendix). caudally broad; morphology of the pubic peduncle Femur. Five femora are preserved. Complete of the ilium relatively short and triangular, with a femora representing adult and subadult individu- proximal region that is craniocaudally much wider als are preserved in MPCA-Pv SM 2, 42 and 43, than the distal end; ischial peduncle of the ilium with sizes ranging from 35 centimeters to near formed by two protrusions of similar size; posta- a meter in �roximodistal length. The overall cetabular process of the ilium with a caudodorsally femoral morphology is similar to that of other oriented dorsal margin, rising dorsally relative hadrosauroids. There is no complete enclosure to the acetabular margin; distal articular surface of the cranial intercondylar groove by the projec- of the iliac peduncle of the ischium cranially ori- tions of the condyles (Fig. 9C, D), contrasting with ented; and acetabular and caudodorsal margins of the condition present in Secernosaurus koerneri the iliac peduncle of the ischium becoming slightly (Bonaparte & Rougier, 1987). The character does to greatly divergent near the proximal region of not appear to be ontogenetically variable in Will- the peduncle. Willinakaqe salitralensis gen. et sp. inakaqe gen. nov., because the open condition is nov. also displays the following synapomorphies present in all the subadult and adult specimens. of Saurolophinae: �resence of a �remaxillary This character is considered as homoplastic among foramen located rostrally and ventrolaterally to hadrosauroids, but valid for specific differentia- the rostral margin of the external naris; and pubic tion (Godefroit et al., 1998). peduncle of ischium parallel with the ischial shaft. Juárez Valieri et al.: A new hadrosauroid from Patagonia 229

Willinakaqe gen. nov. displays the following char- cranial region and a concave caudal one upon the acters supporting its inclusion into the unnamed acetabulum; large and extensive supraacetabu- clade comprising those taxa closer to Gryposaurus lar �rocess located dorsal to the acetabulum; than to Brachyolophosaurus in the �hylogeny prominent �ostacetabular �rocess of the ilium; published by Prieto-Márquez (2010, figure 5): ischial shaft straight and caudoventrally oriented; Dorsoventral depth of the central plate of the ilium ischium ithout foot-like expansion. Likewise, low; and ratio between the length of metatarsal Willinakaqe gen. nov. and Secernosaurus present III and its mediolateral breadth at midshaft lesser several characters which could be considered as than 4.50. No unambiguous synapomorphies are plesiomorphic relative to Saurolophidae, such as a present in all the resulting trees of this analysis jugal with a ventral margin of the rostral process supporting the association between the Grypho- dorsal to level of lateral ridge of the ectoptery- saurus species and Willinakaqe salitralensis gen. goid shelf, a maxilla-jugal contact restricted to a et sp. nov. and their closer relatives, the unnamed finger-like jugal process on the caudal margin of Big Bend taxon of Prieto-Márquez (2010) and maxilla, less than thirty-five tooth �ositions in Secernosaurus koerneri. Four characters associate both dentary and maxillary dental batteries dur- these latter three species: coracoid with slightly ing ontogeny, no less than four foramina arranged longer scapular facet respect to the lateral margin in a sub-horizontal row along the lateral wall of of the glenoid; presence of a brevis shelf at the the maxilla, and less than nine sacrals. base of the �ostacetabular �rocess of the ilium The new taxon Willinakaqe salitralensis repre- (see discussion in Prieto-Márquez’s character sents the second hadrosauroid species recognized 244); iliac medioventral ridge on the medial side from South America, because it displays several of the �ostacetabular �rocess ell-developed, differences ith Secernosaurus koerneri, hich oblique, and expanded into a flange forming the contains the material previously assigned to “Kri- medial margin of an extensive brevis shelf that tosaurus” australis ( Prieto-Márquez & Salinas, faces more ventrally than medially; and presence 2010). These differences include the cervical ver- of a craniocaudally oriented median ridge on the tebrae with a lower angle of divergence between dorsolateral surface of the postacetabular process the �ostzygapophyses; dorsal vertebrae ith a of the ilium. Finally, Willinakaqe salitralensis shallow fossa positioned on the lateral surface of gen. et sp. nov. is supported as the sister taxon of the neural arch, upon the base of the transverse Secernosaurus koerneri by five character states in process; tall neural spines in sacral and proximal the Prieto-Márquez analysis: height of the neural caudals more than four times the centrum height; spine greater than 2.10 times that of the centrum presence of a ventral keel in the proximal sacral in the tallest caudal dorsal or sacral vertebrae; vertebrae; the postzygapophysis of the proximal angle greater than 115° between the lateral mar- caudal vertebrae situated at a level dorsal to the gin of the facet for scapular articulation and the prezygaphophysis; distal region of the �osta- glenoid in the coracoid; supra-acetabular process cetabular process of the ilium ventrally deflected; of the ilium asymmetrical, with a caudally skewed and femur with open cranial intercondylar groove, lateral profile; caudodorsal margin of ilium with among others. Other characters diagnostic of a well-defined ridge continuous with the dorsal Willinakaqe salitralensis gen. et sp. nov., as those margin of the proximal region of the postacetabu- present in the premaxilla, are not comparable with lar process; mid-shaft of the ischium with a very those of Secernosaurus koerneri because this ele- thick shaft. ment is unknown in the latter genus. Some characters indicating a derived �lace- Based on the phylogenetic scheme of the had- ment for Willinakaqe gen. nov. and Secernosau- rosauroids presented by Prieto-Márquez (2010), rus in relation to Telmatosaurus and more basal Willinakaqe salitralensis gen. et sp. nov. (their taxa includes: diamond-shaped dentary teeth Salitral Moreno OTU) is found as the sister taxon with only one straight medial keel and ith to Secernosaurus koerneri within Saurolophinae. small denticles; dentary ith more than thirty This analysis present decay index values of only alveoli and ith more than two teeth �osition; one step, and bootstrap frequency values of less strong inflection of the dentary dorsal border than fifty percent, for support of all the succes- forming a low mandibular symphysis; coronoid sive clades including the South American taxa process of the dentary bone vertically oriented, with other saurolophines different of the “Big lacking a rostralward inclination; scapular blade Bend Moreno” taxon. Furthermore, no less than slightly distally expanded; sternal caudoventral nine reversal events are necessary along the process well developed, relatively long, and thick hypothesized evolutionary history of the clade relative to the sternal ‘handle’; ilium with dorsal comprising Willinakaqe gen. nov., Secernosaurus border displaying an inflexion between a convex and the Big Bend Moreno taxon to support their 230 Revista del Museo Argentino de Ciencias Naturales, n. s. 12 (2), 2010 derived �osition ithin Saurolophinae. A more formaciones del Cretácico Superior del área del detailed study of the South American forms and Lago Pellegrini (prov. de Río Negro, Rep. Argenti- additional specimens are necessary in order to na). Rev. Asoc. Geol. Arg., 29: 85-104. confirm the position of both Secernosaurus and Bonaparte, J.F. 1984. Nuevas pruebas de la conexión fí- sica entre Sudamérica y Norteamérica en el Cretá- Willinakaqe gen. nov. cico Tardío (Campaniano). IIIº Congr. Arg. Paleont. The presence of hadrosauroid remains in the y Bioestrat., Actas: 141-149. Late Cretaceous of Patagonia is of particular in- Bonaparte, J.F. 1996. Cretaceous Tetrapods of Argen- terest for understanding the paleobiogeographic tina. Münch. Geowiss. Abhandl. (A), 30: 73-130. dispersal events occurring during this timespan, Bonaparte, J.F. & G.W. Rougier. 1987. The�� Late Creta- given that this group of dinosaurs is considered ceous fauna of Los Alamitos, Patagonia, Argentina. as being of Laurasian origin (Sues & Averianov, Part VII - The hadrosaurs. Rev. Mus. Arg. Cienc. 2009). The original referral of the material from Nat. B. Rivadavia, 3(3): 155-161. Bonaparte, J.F., M.R. Franchi, J.E. Powell & E.G. the Los Alamitos Formation to the genus Krito- Sepúlveda. 1984. La Formación los Alamitos (Cam- saurus (Bonaparte et al., 1984) and the purported paniano - Maastrichtiano) del sudeste de Río Negro, lambeosaurine condition of MPCA-Pv SM 2 ad- con descripción de Kritosaurus australis n. sp. (Had- vanced by Powell (1987) suggested than at least rosauridae). Significado paleogeografico de los ver- two different groups of hadrosauroids dispersed tebrados. Rev. Asoc. Geol. Arg., 39(3-4): 284-289. to South America during the Late Cretaceous. Brett-Surman, M.K. 1979. Phylogeny and palaeobioge- The phylogenetic placement of the South Ameri- ography of hadrosaurian dinosaurs. Nature, 277: can hadrosauroids presented by Prieto-Márquez 560-562. Brown, B. 1914. Corythosaurus casuarius, a new crest- (2010) suggests only a dispersal event for the ed dinosaur from the Belly River Cretaceous, with group followed by a local radiation. Whether or provisional classification of the family Trachodonti- not these biogeographical events ocurred dur- dae. Bull. Amer. Mus. Nat. Hist., 33: 559-565. ing the Campanian, and through the Isthmus of Casadío, S.A. 1994. 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