VII Jornadas Internaciones sobre Paleontología de Dinosaurios y su Entorno. Salas de los Infantes, Burgos

The Gondwanan rhabdodontomorphans and the origins of the Rhabdodontidae

DIEUDONNÉ, P.E.1, TORTOSA, T.2, DÍAZ‐MARTÍNEZ, I.3, RUIZ‐OMEÑACA, J.I.1, TORCIDA FERNÁNDEZ‐BALDOR, F.4, CANUDO, J.I.1 1 Grupo Aragosaurus−IUCA, Área de Paleontología, Facultad de Ciencias, Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain, [email protected], [email protected], [email protected] 2 Réserve Naturelle Nationale Sainte‐Victoire, Conseil Départemental des Bouches‐du‐Rhône, 52 Avenue de Saint‐Just, 13256 Marseille Cedex 20, France, [email protected] 3 CONICET—Instituto de Investigación en Paleobiología y Geología, Universidad Nacional de Río Negro, General Roca 1242, 8332 Fisque Menuco, General Roca, Argentina, [email protected] 4 Museo de Dinosaurios de Salas de los Infantes and Colectivo Arqueológico−Paleontológico Salense (CAS), Plaza Jesús Aparicio 9, 09600 Salas de los Infantes, Burgos, Spain. [email protected]

Keywords: Gondwana, Rhabdodontomorpha, Rhabdodontidae, synapomorphies

The fossil record of small bipedal ornithopods is almost invisible at the beginning of the Cretaceous in Western Europe. However, an increasing number of sites record basal ornithopod remains from the Barremian onwards. Examples are reported from England (Galton, 1974), France (Néraudeau et al., 2012) and Spain (Ruiz‐Omeñaca et al., 1995; 2012; Rauhut, 2002). This increment in diversity is particularly significant by observing the teeth, of which a minority bears a distinct “rhabdomorphan” morphology (e.g. Canudo et al., 2010). However, no post‐cranial skeleton has ever been described in association with these teeth. Incomplete and disarticulated remains from at least five small‐bodied ornithopods of three distinct ontogenetic stages were collected at the Vegagete dig‐site. This material comes from the Barremian‐Albian of the Castrillo de la Reina Formation (Dieudonné et al., 2016 and references herein). The Vegagete taxon appears to bear some very surprising characters which ・ despite its slender and gracile appearance place it as the most primitive member of Rhabdodontidae (Dieudonné et al., 2016). This clade was recently diagnosed by three forearm synapomorphies: 1) a humerus lacking a bicipital sulcus, 2) a humerus of which the lateral side is concave between the head and the deltopectoral crest, and 3) a prominent olecranon process on the ulna (Dieudonné et al., 2016). The presence of a comparatively larger primary ridge on the dentary teeth is very probable, though its greater prominence should be verified in more primitive ornithopods. A crest‐ like fourth trochanter is very likely present, but this process is broken in the Vegagete ornithopod, so this apomorphy could not be assessed at the base of the clade. The informal group “Rhabdomorpha” was recently redefined and renamed within the new superfamily “Rhabdodontomorpha” (Dieudonné et al., 2016), which contrary to previous conceptions (Ruiz‐Omeñaca, 2001; Pincemaille, 2002) excludes any relation with the American genus Tenontosaurus and strengthens the kinship of Rhabdodontidae with the Australian ornithopod Muttaburrasaurus. Their synapomorphies are 1) a subrectangular maxillary process of

65 VII Jornadas Internaciones sobre Paleontología de Dinosaurios y su Entorno. Salas de los Infantes, Burgos

the jugal (Fig. 1A, B, C); 2) a strongly bowed humerus in antero‐posterior view; 3) a significant lateral deflection of the preacetabular process (Fig. 2A, C); 4) the dorsal margin of the preacetabular process is transversely expanded to form a narrow shelf (Fig. 2A, 2C); 5) the dorsal margin of the ilium is mediolaterally thickened above its ischiac peduncle (Fig. 2A, 2C). A combined character that could be plesiomorphic is a femur that has a non‐constricted trochanteric fossa. Leaellynasaura amicagraphica is made a member of this group by the anterior maxillary process of its jugal bearing parallel superior and inferior borders (Herne, 2013, fig 5.41, Fig. 1B), and the combined presence of a femur which has a shallow trochanteric fossa (Rich & Vickers Rich, 1989, fig. 6, 7).

Figure 1: Rhabdodontomorphan synapomorphies. Left reconstruction of the skull of Muttaburrasaurus langdoni (1A) (Bartholomai & Molnar, 1981, fig. 2A), Leaellynasaura amicagraphica (1B) (Herne, 2013, fig. 5.41), and left lateral view of the jugal of Zalmoxes robustus (1C) (Weishampel et al., 2003, fig. 6A). Right ilia of M. langdoni (2A) (photo courtesy of M. Herne) and Zalmoxes shqiperorum (2C) (Godefroit et al., 2009, fig. 18C, D) in dorsal (above) and lateral (below) views; left ilium of the Vegagete ornithopod in posterior view (2B). Right metatarsal I of Hypsilophodon foxii (3A, Galton, 1974, fig. 58A), Tenontosaurus tilleti (3B, Forster, 1990, fig. 22B), Camptosaurus dispar (3C, left reversed, USNM 5473), the Vegagete ornithopod (3D), and Rhabdodon sp. (3E, Chanthasit, 2010, fig. 4.34A) in anterior (3A‐C, 3D to the left), posterior (3D to the right), and medial (3E) views. Abbreviations: mpj, maxillary process of jugal; mlth,

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mediolateral thickening above the ischiac peduncle on the dorsal margin of the ilium; ppsh, preacetabular process shelf. Scales: 10cm (1A, 2A), 1cm (1B), 5mm (2B, 3D), 5cm (1C, 2C, 3A‐C, 3E).

Unexpectedly, the distal end of the first metatarsal appears to bear one character which could be plesiomorphical for the rhabdodontids, the origins of which may lie amongst Gondwanan ornithopods. In the Vegagete ornithopod (MDS‐VG,171, Fig. 3D), and possibly too in Rhabdodon sp. based on illustrations (MDE‐C3.510, Fig. 3E) the distal ligamentary fossae of the first metatarsal are oriented antero‐posteriorly, with the plantar posterior surface laid laterally against the second metatarsal. A “planto‐lateral” orientation was also described for the Early Cretaceous Australian ornithopod VOPC III (MV P221080, see Herne, 2013 to fig. 10.18B). This configuration largely contrasts with the usual planto‐posterior orientation observed in most other ornithischians (e.g. in Galton, 1974; Galton et al., 2015; Forster, 1990, Fig. 3A‐C). Evidence points towards an affinity between the rhabdodontids and a very specific – yet very diverse – group of southeastern Gondwanan ornithopods that comprise Muttaburrasaurus and Leaellynasaura. All of these taxa are grouped together into the Rhabdodontomorpha. It is worth noting that this superfamily includes taxa that are very distant both temporally and spatially. What is more, rhabdodontomorphan remains are rather incomplete. As a consequence, it is not surprising that still very few synapomorphies could be attributed to this group for the moment.

References Canudo J.I., Gasca J.M., Aurell M., Badiola A., Blain H.A., Cruzado‐Caballero P., Gómez‐ Fernández D., Moreno‐Azanza M., Parrilla J., Rabal‐Garcés R., Ruiz‐Omeñaca J.I. (2010): La Cantalera: An exceptional window onto the vertebrate biodiversity of the Hauterivian‐Barremian transition in the Iberian Peninsula. Journal of Iberian Geology, (36, 2), 205‐224. Chanthasit P. (2010): The ornithopod dinosaur Rhabdodon from the Late Cretaceous of France: anatomy, systematics and paleobiology. Unpublished PhD Thesis, Université Claude Bernard, Lyon, 195 pp. Dieudonné P.E., Tortosa T., Torcida Fernández‐Baldor F., Canudo J.I., Díaz‐Martínez J.I. (2016): An unexpected early rhabdodontid from Europe (Lower Cretaceous of Salas de los Infantes, Burgos province, Spain) and a re‐ examination of basal Iguanodontian relationships. PLoS ONE, (11,6), e0156251. Forster C.A. (1990): The postcranial skeleton of the ornithopod dinosaur Tenontosaurus tilletti. Journal of Vertebrate Paleontology, (10, 3), 273‐94. Galton P.M. (1974): The ornithischian dinosaur Hypsilophodon from the Wealden of the Isle of Wight. Bulletin of the British Museum (Natural History), Geology Series, (25,1), 3‐152. Galton, P.M., Carpenter, K., Dalman, S.G. (2015): The holotype pes of the Morrison dinosaur Camptonotus amplus MARSH, 1879 (Upper Jurassic, western USA) – is it Camptosaurus, Sauropoda or Allosaurus? Neues Jahrbuch für Geologie und Paläontologie‐Abhandlungen, (275,3), 317‐335. Godefroit P., Codrea V., Weishampel D.B. (2009): Osteology of Zalmoxes shqiperorum (Dinosauria, Ornithopoda), based on new specimens from the Upper Cretaceous of Nălaţ‐Vad (Romania). Geodiversitas, (31,3), 525‐53. Herne M.C. (2013): Anatomy, systematics and phylogenetic relationships of the Early Cretaceous ornithopod dinosaurs of the Australian‐Antarctic rift system. Unpublished PhD Thesis, University of Tasmania, Murdoch University. Néraudeau D., Allain R., Ballevre M., Batten D.J., Buffetaut E., Colin J.P, (2012): The Hauterivian‐Barremian lignitic bone bed of Angeac (Charente, south‐west France): stratigraphical, palaeobiological and palaeogeographical implications. Cretaceous Research, (37), 1‐14.

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Pincemaille‐Quillevere M. (2002): Description d'un squelette partiel de Rhabdodon priscus (Euornithopoda) du Crétacé supérieur de Vitrolles (Bouches du Rhône, France). Oryctos, (4), 39‐70. Rauhut O.W.M. (2002): Dinosaur teeth from the Barremian of Uña, Province of Cuenca, Spain. Cretaceous Research, (23), 255‐263. Rich T.H.V., Vickers Rich, P. (1989): Polar dinosaurs and biotas of the Early Cretaceous of southeastern Australia. National Geographic Research, (5, 1), 15‐53. Ruiz‐Omeñaca J.I., Canudo J.I., Cuenca‐Bescós G. (1995): Dientes de dinosaurio (Ornithischia y Saurischia) del Barremiense Superior (Cretácico Inferior) de Vallipón (Castellote, Teruel). Mas de las Matas, (15), 59‐104. Ruiz‐Omeñaca J.I. (2001): Dinosaurios hipsilofodóntidos (Ornithischia: Ornithopoda) en la Península Ibérica. In: Actas de las I Jornadas Internacionales sobre Paleontología de Dinosaurios y su Entorno (Colectivo Arqueológico y Paleontológico de Salas, Ed.). Salas de los Infantes, 175‐266. Ruiz‐Omeñaca J.I., Canudo J.I., Cuenca‐Bescós G., Cruzado‐Caballero P., Gasca J.M., Moreno‐Azanza M. (2012): A new basal ornithopod dinosaur from the Barremian of Galve, Spain. Comptes Rendus Palevol, (11), 435‐444.

68 VII Jornadas Internaciones sobre Paleontología de Dinosaurios y su Entorno. Salas de los Infantes, Burgos

Reconstructing hypothetical sauropod tails by means of 3D digitization: Lirainosaurus astibiae as case study

DÍEZ DÍAZ, V.1, VIDAL, D.2,3 1: Museum für Naturkunde ‐ Leibniz Institute for Evolution and Biodiversity Science, Invalidenstrasse 43, 10115 Berlin, Germany, [email protected] 2: Unidad de Paleontología, Universidad Autónoma de Madrid, Darwin 2, 28049 Madrid, Spain, [email protected] 3: Grupo de Biología, Facultad de Ciencias, UNED, Paseo Senda del Rey, 9, 28040 Madrid, Spain

Keywords: 3D digitization, biomechanics, tail, Sauropoda, Titanosauria.

Three‐dimensional (3D) surface digitalization of fossils is rapidly improving its quality while reducing its cost and developing classical and new research palaeontological techniques in the last years. 3D models allow researchers to easily access, study and visualize specimens, as well as minimize manipulation of original specimens, thus helping in their preservation (Mallison & Wings, 2014). Two of the fields which have benefited from it are biomechanics and skeletal reconstruction. The ease of analyzing 3D models with computer‐aided design (CAD) software – unlike the physical specimens, heavy, fragile and difficult to work with – allows studying skeletal ranges of motion with more accuracy, and even with more detail. Several works on sauropod dinosaurs have used 3D digitalization in recent years for different purposes, e.g. 3D skeletal reconstructions (Mallison, 2010a; Tschopp et al., 2015; Martínez et al., 2016), retrodeformation (Tschopp et al., 2013), or biomechanics (Mallison, 2010b). Thanks to all these new techniques and analyses, we can take one step further and reconstruct skeletal parts and study their biomechanics, even having only preserved partial remains. These preserved remains, however, must be as complete as possible; for example, when reconstructing a tail it is helpful to have vertebral remains from each sector: anterior (with proximal caudal vertebrae), middle and posterior (with distal caudal vertebrae). That is the case of the Upper Cretaceous Iberian titanosaurian sauropod Lirainosaurus astibiae (Sanz et al., 1999). Forty caudal vertebrae were recovered in the fossil site of Laño (northern Spain) (see Díez Díaz et al., 2013 for a detailed description), but not all were well preserved. Lirainosaurus isolated vertebrae stem from several individuals of different sizes, with only four coming from a single individual (Díez Díaz et al., 2013). In order to reconstruct the vertebral sequence, the published measurements and figuration of articulated remains of several titanosaurs were studied for comparison: basal titanosaurs (Andesaurus, Malawisaurus), non‐ saltasaurine lithostrotians (Alamosaurus, Baurutitan, Dreadnoughtus, Opisthocoelicaudia, and Trigonosaurus) and the saltasaurine Neuquensaurus. Given the caudal series of titanosaurs have a conservative pattern in their height/length ratios, which increases steadily toward the posterior end, Lirainosaurus isolated vertebrae can be easily arranged in a hypothetical sequence. The position of the preserved vertebrae was determined by comparing the length/height ratio of the vertebrae with the studied known caudal series and by comparing the anatomical features of the sample. The number of caudals remains reasonably constant throughout sauropod evolution, being between 40‐50 caudal vertebrae in most taxa (Upchurch et al., 2004), like in the

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