sign in sign up
<<
Home , Concornis, Megaraptor, Santanaraptor, Unenlagia

Reu. Mus. Argentino Cienc. Nat., n.s. 611): 61-66,2004 Buenos Acres, ISSA' 1514-5158

Unquillosaurus eeibali Powell, a giant maniraptoran (Dinosauria, ) from the Late of Argentina

Fernando E. NOVAS' & Federico L. AGNOLINP

'CONICET. ZMi~seoArgentino de Ciencias Naturales aBernardino 12ivadaviam, Ax A. Galiordo 4.70; C1405DJR Buorios Aires, Argentina. Telpax: 4981 9282, email: [email protected].

Abstract: A reviewed anatomy and phylogenetic relationships of the theropod Unquillosauriis eeibali is presented. This is represented hy an isolated pubis Crom 1,os Blanquitos Formation (Nlaastrichtian),from the province of Salta, NW Argentina. The size of the bone (51 cm long) originaliy lead to interpret chis theropad as a member of the large "". However, the pubic anatomy of Unquilloseurus is more eonpuent with that. present in metornithine caelurasaui.ians, a group including , Theririnosauroidea, Oviraotorosauria. Dcinonvchosauria, and Aves. Derived features presont in U~im~illosaurus

Moreover, some Laits sharEd with eariy avians (e.2, pubic foot proximodistally tall and craniocaudally short), suggest that this may be more ciosoly related to than suspected. The set of autapomorpiiic Foatures recognized in the pubis indicates that Unquilloseurus may belong to an endemic lineage of large maniraptaran theropods.

Key words: Thoropoda, Man~raptora,Late Cretacoous, Argentina

Uuguillosaurus ceibali was described by Jai- derived linenlagia comahuensis (Novas & Puer- me Powell (1979) on the basis of an almost com- ta, 1997). Thisvariety of offers valuable plete left pubis, discovered in Maastrichtian beds anatomical information that invites to reconsider CrornSaltaProvince, hW Argentina (Fig.1).Powell the phylogenetic relationships of Unquillosaurus. (1979) interpreted this dinosaur as a large carnosaur of uncertain reiationships. With the MATERIAL AND METHODDS exception of some brief coruments made by Molnar et al. (1990) and Bonaparte (1996), no further Institutional abbreviations. AMhW, American reierences to the phylogenetic relationships of this Museum of Natural History, New York; HMN MB, theropod are found in the literature. The Humboldt Museum fur Naturkunde, Berlin; fragmentary nature of Unquillosaurus, coupled MACN, Museo Argentino de Ciencias Naturales with the limited knowledge of Gondwanan <

Coelnrosauria (&., Bonaparte, 1991,1996; Novas, WM, Yale Peabody Museum, New Haven. 1997,1998; Coria& Salgado, 1995). Other findings Studied specimens: The following specimens demonstrate that was inhabited have been used for this study: Patagonykuspuertai by a diversity of non-avian coelurosaurian (PVPH 37), libratus (AMNH 5468), theropods, including (Kellner, fragilis (AMNH 6767), 19991, a possible oviraptorosaur (Frankfurt & lithographica (HMN MB 1880181, and casts of Chiappe, 1999), different alvarezsaurids London and Eichstatt specimens), (Bonaparte, 1991; Novas, 1997), and the highly sastrei (MACN-CH 8941, Ceratosa~lrusnasicornis 62 Reucsla del Museo Argenlcno de Ciencias Naturales, n. s. 6 ilj,2004

(USNM 4735), antirrhopus (AMNII Tble I. Measurements of pub~sof 1Jnquzllosaurus 3015, MCZ 4371, YPM 5205, 5206, 52361, cezbalz Piatni:zkysaurus floresi (MACN-CH 8951, Rahoo#auis ostromi (UA 8656), and Proximodistal length 514 mm comahuensis (PVPH 78). Craniocaudai diameter of proximal end 155 mm % Sysiematic ~zomenclature.In this paper we are Craniocaudal diameter of distal foot 11.5 mm followingthephylogenetic hypothesis andsystem- Greatest transverse diameter of shaft 36 mm atic nomenclature employed by Xu et al. (2002) Lesser transverse diameter of shaft 56 mm for coelurosaurii~ntheropods.

SYSTEMATIC PALEONTOLOGY (e.g., Carnotaurus, ; Theropoda Marsh, 1881 Gilmore, 1920; Bonaparte et al., 1990) and Trtanurae Gauthier, 1986 ~Alberlosauruslibratus AMNH Coelurusauria Huene, 1920 5468).In contrast, its reduced size resembles more Gauthier, 1986 that of derived coelurosaurians, such as Metorn~thesPerle, Norell, Chiappe & Clark, , Alvarezsauridae, 1993 (e.g., Unenlagia, ; Novas & Puerta, 1997; Burnham et al., 2000), and primitive birds Unquillosaurus Powell, 1979 (e.g., Archaeopteryx, Rahonauis; Wellnhofer, 1974; Forster et al., 1998). On the other hand. the ischi- . Unquillosuurus ceibali Powell, 1979 adic facet of the pubis is dorsoventrally low, compa- rable to that oSDmmamsauridae, but different from Sir-atigraphic distribi~tion.Los Blanquitos For- the well develoued one of most non-coelurosaurian mation, Salta Group (Masstrichtian; Salfity & theropods (e.g., Ceratosaurus, , Marquillas, 1999). Piatnit&saurus, 'fyrannosauridae; Gilmore, 1920; Geographic distributioiz, Arroyo Morterito, Si- Bonaparte el al., 1990; Bonaparte, 1986; Osborn, erra de la Candelaria, Salta Province, hW Argen- 1917). The ohturator fbramen isventrally open, as tina. it occurs in most tetanurans (Gauthier. 1986) (Fig. 2). Unquillosauncs ceibali Powell, 1979 The intersection between the proximal mar- (Fig. 1) gin of the pubis and the longitudinal axis of the pubic shaft describes an angle of approximately Emendeddiugmsis. The pubis of linquillosaums 45 degrees, reflecting an opisthopubic condition is proportionaliy long and slender It is large (61,4 ofthe bone (Fig. 2). An opisthopubic pelvis is diag- cm long; Table 1) in comparison with other basal nostic of Metornithes (Xu et al., 20021, as it is Maniraptora (= Ornitliolestes + Metornithes; Xuet present in Alvarezsauridae (Novas, 1997), al., 20021, such as Patagon.ykus puertui PVPI-I 37 Therizinosauroidea (Barsbold, 19791, and ('25 cm), Deinonychus antirrhopus MCZ 4371 (38 (= + Aves; Sereno, 1997; Clark cm), Urlenlngia comahuensis PVPH 78 (32 cm), et al., 2002; Xu et al., 2002). Rahonauis ostrorni UA 8656 (6 cm). Its proximal The proximal 3/n of the pubic shaft are end presents a thick edge defining a deep groove, craniocaudally compressed, in contrast to most which was originally interpreted by Powell (1979) theropods (e.g.,Allosaurus,Pataponykus;Gilmore, as diagnosticoSUnp.*illosaum,sceibali.However, this 1920; Novas, 1997) in which the pubis is rod-like abnormal morphology (not recorded in other proximal to the pubic symphysis. The condition saurischian dinosaurs) is better explainedas the bro- mentioned above for Unquillosaurus results in a ken pubic pedicle of adhered to the external prominent external, longitudinal ridge (named surface of pubis. In fact, this piece of bone resembles "crcsta lateral" by Powell, 1979; Fig.1 A, Bi. The the pubic pedicle of the ilium of Deinonychw and margins of the pelvic canal of Unquillosaurus are Unenlagia (Ostrom, 1969; Novas & Puerta, 1997) medially convex, differing from most theropods in beingcraniocaudally extended, ventrally concave, (e.g., Allosaurus, , Patagon.ykus, and with the cranial and ventral margins formingan ; Gilmore, 1920; Norell & iWakovicky, angle exceeding 90 degrees in side view (Fig. 1A). 1999; Novas, 1997; Osborn, 1917) in which the The proper acetabular surface is represented margins are medially concave (Fig. 3). The by a reduced surface located caudally to the facet craniocaudal compression of the proximal pubis of for the pubic pedicle of the ilium. The acetabular Unquillosaurus contrasts with the craniocaudal surface of 1Jnquillosaurus is more reduced than in expansion of its distal half, thus resultingin alon- Nocas & Agnolcn Unqu~llosauri~s,a large man~raptorantheropod

A D E

Fig. 1. Unquillosaurus ceibali left pubis. A) lateral, Bj cranial, Cj distal (restored), Dj medial, and E) caudal.riews. AS, acetabular surface; CaE: caudal process of pubic foot; CrP, cranial process of pubicfoot; FIE facet for the iliac pedicie; LR, iateral ridge; PF pubic foot; PPI, Iliacpubic pedicel. Scale bar 10 cm.

A B C D E

Fig. 2. Pubis of several theropods in lateral view. Not to scale. A) Unquillosaurus, B) Unenlagia, C) Ouiraptor, D) Tyrannosaurus,E). 64 Reuzsta del Museo Argentzno de Czenczas Natarales, n s 6 (I), 2004

A B C D

Fig. 3. Reconstructed pubises of several theropods in cranial view. Not to scale. A) , B) Patugonykus, C) Unenlagia, D) Unquillosaurus (without the pubic pedicle of ilium).

gitudinal "twisting" of the bone (Fig. I). In most & Puerta, 1997; Burnham el al., 2000) in which it theropods, instead, the cranial and caudal mar- is well developed. However, in Unquillosaurus the

symphysis is absent (Figs. 1, 31, unlike most theropods (e.g., Allosaurus, Carnotaurus, DISCUSSION Ornithominzus, Velociraptoq Unenlagia, Rahomvis, Archaeopteryx; Gilmore, 1920; Bonaparte el al., The pubis of Unquillo.saurus clearly indicates 1990; Osborn, 1917; Norell & Makovicky, 1999; that this genus is not a member of Abeiisauroidea Novas & Puerta, 199'7; Forster et al., 1998; (= + Abelisauridae; Novas, 1992; Wellnhofer, 1974) in which the apronis transversely Carrano et al., 2002). In the later ones the pubis wide and arelatively extended symphysis is present. retained plesiomorphic features absent in In this sense, Unquillosaurus resembles Unquillosaurus, such as: obturator foramen en- alvarezsaurids (e.g.,Palagonykus; Novas, 1997)and closed by hone, ischiadic facet proximodistally basal pygostilian birds (e.g., Confusiusornis, deep, extended pubic symphysis, and pnbic boot Changchengornis, ; Chiappe, 2001) in enlarged and dorsoventrally depressed. Besides, having a pubic symphysis reduced to the distal ex- the pubic foot of Unqu~llosa~ruslacks the lateral tremity ofthe bones. Notably, the distal end of the inset described in Carnolaurw and the pubis of Unquillosaurus is medially flattened, (Carrano et al., 2002). Unquillosaurus may not and lacks marks for the articulation with the oppo- belong to Carnosauria (= + site bone (Fig. ID). ; Padian et al., 1999) be- The pubic foot is craniocaudally short and cause carnosaurs retained a pubic symptiysis and proximodistally deep. The cranial projection ofthe developed very large pubic boots. Both conditions boot is more reduced than inDeinonychus (Ostrom, are absent in Unquillosaurus. 1975), Achillobator (Perle et al., 19991, and On tile contrary, the pubic anatomy of Elociraptor (Norell & Macovicky, 1999) thus re- Unquillosaurus is more congruent with that sembling the smaller proportions present in present in theropods more derived than Cmosauria Bambiraptor (Burnham et al., 20001, Unenlagia (e.g., , a group including theropods (Novas & Puerta, 19971, and birds (Chiappe, more closely related to birds; Gauthier, 1986).The 2001). Also, the caudal process of the pubic foot is following apomorphic trait supports the inclusion strongly reduced as in primitive birds such as of Unquillosaurus within Metornithes Rahonauis and Archaeopteryx Wellnhofer, 1974; (=Alvarezsauridae + ((Therizinosauroidca + Forster el al., 1998) but differingfrom some basal ) + Paravesj; Xu et al., 2002): 1) paravians (e.g., Unenlagia, Bambiraptor; Novas opisthopubic pelvis (but see Chiappe, 2001, fi~ral- Novas & Agnol~n.Unquzllosaurus, a large manraptoran theropod 65

ternativeinterpretationonthischaracter).Thefol- - 1996. Crotaceous terrapods of Argentina. lowing featuresof ill^^^^^^^ are presentin Munchner Geoioissen. Abhandl. 30 (A):73-130. + paraves(=~~i~~~~~h~~~~~i~ + A~~~;sereno, Bonaparte, J.F., Novas, FE. R.A. Coria. 1990. pedicle of ilium crarliocaudally Carnolaurus sastrei Boilaparte, the horned, lightly built carnoaaur from the Middle Cretaceous of wide; 2) ventral margin of pubic pedicle strongly Nat. Xist. Mus. Los Angrles CoiLnty, concave; 3) cranial process of pubic loot short; 4) cOntrib, sei,416: le~lgthof puhic foot less than 30 percent of pubic Burnham, I)., K. Dorstler, P Currio, R. Bakker, Z.Zhou total length. Notably, lJnquillosuurus shares with & J. Ostrom. 2000, Remarkable new Birdlike dino- basal birds (e.e..- . Archaeoutervx: saur (Theropoda: Muniraptora) from the upper Wellnhofor. 1974; Forster 'et al., 1'998; a Cretaceous of Montana. Paleontol. Contrib. proximodistally tall and craniocaudally short pn- Uniu.Karlsas 13: lSl4. foot, shorter than iil Deinonvchas, Carrano, MT; S.D. Sampson, & C.A. Forster. 2002. The osteology of Masiahasaurws knopfleri, a Velociraptor, and Unenlagia. Resides, the highly Email abelisauraid (uinosauria: ~h~~~~~~~~from reducedpubicsymphysisof UiyuillO~a~rusresem- the Late Cretaceous of Madagascar. JOIL,:Vert. bles that of alvarezsaurids (Novas, 1997) and birds pu'aleont. 22(31: 510-534. more derived than Archaeopte~x(Cl~iappe, 2001). Chiappe L. 2001. Phylogenetic relationships among 111 surn, available information supports basal birds. In: Gauthier, J & G. Gall eds., A'em Unquillosaurus as a member of Metornithes (sensu perspectives on the origin and early euolution of Xu et al., 2002). Its large size (comparable to birds: Proceedings of the li~lernatio,~alS,yntpo- Achillobator; Perle et al., 1999) makes siurr~in Honor of Jolin H. Ostrom. Pp. 126-139. Peabody Museum of Natural History Yale Univer- Ur~quillosaurusone of the largest known sity. maniraptorans. Unquillosaurus adds to the list of Clark, J.M. , M.A. Norell & PJ. Makovicky 2002. hird-like theropods discovered in , such Cladistie approaches to the relaitonships of birds to othcr theropad dinosaurs. 1r~:L.M. Chiappe & I,. Witmer, edr;., Merozoic birds. Aboue the head of u. radiation of large-sized maniraptorans occurred dinosaurs. Pp. 31-61, University of Calirornia in South America during the Late Cretaceous, prob- Press. ably includingother recent discoveries (e.g., Coria Coria, R., ' Currie, D. Ehorth, A. Garrido & E. Koppelhus. 2001. Nuevos vertebrados fiisiles del et al., 2001; Novas et al., 2003). The unique puhic CretAeico Superior de Neuqutn. Ameghiniaj~a features also prompt to the conclusion that 38(41 suppi.: 6R. Ilnquillosaurus was part of a lineage of predatory Coria, R. & I.. Salgado. 1995. A new giant carnivorous dinosaurs endemic from South America. dinosaur from the Cretaceous of Patagonis. Na- ture 377: 224-226. ACLVOWLEDGEMENTS Farster, C., S. Sanrpson , I,. Chiappe & U. Krause. 1998. The Theropod ancestry of birds: new evi- To Jaime Powell for allowing access to the PVL drnco from the Late Cretaceous of Madagascar. Science 279: 1915-1919. collections. R.A. Coria and JF. Bonaparte offered Frankfurt, N. & L. Chiappe. 1999. A possible valuable observations on the manuscript. Figures oviraptorosaur from tho Late Cretaceous of were executed by J. Gonziilez. This research was Northwestern Argentina. Jour Vel-t. Paleont. 19

the Jurasiic and the National Gee: Dinosauria in the United slates National Museum, graphic Society. with special refoxence to the genera Ullosaurus) and Ceratosaurr~s.Bull. US, h'atl. Mus. 110: 1-159. Gauthier, .LA. 1986. Saurischian monophyiy and the , In K.Padian (ed.), The Origin of Rarsbold, R. 1979. Opisthopubic pelvis in the carnivo- Birds and the Evolution of Flight. California rous dinosaurs. Nature 279: 792-793. Academy of Sciences, Memoire 8:l-55. Ronaparte, J.F. 1986. 1,cs dinosauros (carnosaures, Kellner, A. 1999. Short note on a now dinosaur allosauridts, saiiropodes, cetiosauridts) du (Theropoda, Coelurosauria) from the Santana Jurassique Moyen de Cerro Cdndor (Chubut, Ar- Formation (Romualdo Member, Nbian), North- gentine). Ann. Paleonl, Vert.-Inuerl.) 72(3-4): 247- eastern Brasil. Bol. Mus. .%e. Geol. 49: 1-8. 386. Malnar, R., S. Kurzanav & 2. Dong. 1990. - 1991. Los vertebrados fCisiles de la Formaciiin Rfo Carnasauria. In: Weishampel 11, Dodson P & Colorado, de la Ciudad de Neuqutn y cercanias, Osmdlska (eds.), Tl~eDinosauria, pp. 169-209. Crot6cicico superior, Argentina. RL'v.MUS. Arg. Cienc. University of California Press. Nal. "Bernardino Hiuadauia". Paleontologia IV Norell, M. A. & P d. Makovicky 1999. Important fea- (31: 17-123. tures of the dromaeosaurid skeleton 11: infonna- 66 Revista del Musea Argentina de Cieneias Naturales, n. s. 6 (I), 2004

tian fram newly collected specimens of Velociraptor - 1975. On new specimen of the Lower Cretaceoris mongoliensis. Am. Mus. Nou., 3282:l-45. theropod dinosaur Ileino,~yciiusentirrhopus. Novas, F 1992. La evolucidn de 10s dinosaurios Breuiorn, 439:l-21 carnivoras. In: J. Sanz and R. Buscalioni (eds.): Padian, K., J. Hutchinson &T I?oltz. 1999. Phylogenetir Los dinosaurios y su entorno bi6tieo. Pp. 125- definitions and nuinenclature of the major taxo- 1 R? nomic categories of the carnivorous Dinosauria -' 1997. Anatomy of pwertai (Theropoda). Jour Vert. Paleorit. 19 (1): 69-80. (Theropoda, , Alvarezsauridae), fram thc Perle, A,M. Noroll, & J. Clark. 1999.Anew mmiiraptoran Late Cretaceous of Patagonia. Jour Verl. Paleont. theropod -Achillobator gigur~ticus(Dramaeosau- 17(1): 137-166. ridae), from the Upper Cretaceous of Rurkhunt, - 1998. nomunhuaiquii gen. ex. sp. no"., Mongoiia. Nal. Uniu. Mongolia, Pp. 1.106. n largr-clawed, Lato Crelaceous Tiieropod from l'owell, J. 1979. Sobre una asociacihn de dinosaurios y hgeniina. Jour Vert. Paleoat.18 (1):4-9. otras evidoncias de vertrhrados del Cretbcico su- Kovas, I?, J.I. Canale & MP Lsasi. 2003. Un ter6podo perior de la regi6n de la Candelaria, prov de Salla, manirvptor del Campaniano-Maastrichtiano del Argentina. Anzugi~inianaXVI (1-2): 191-204. norte patagdnico. An~egirir~iai~n,40(4) suppi.: 63R. Salfity, .J..4, & R. Marquillas, 1999. La cuenca cretbcico- Novas, F & P Puerta. 1997. Now evidence concerning terciaria del norte argentine. Instil. Geol. Re& avian origins froin the Late Cretaceous of Min., Geologia Argentina 29(19j: 613-626. Patagonia. Nature 387: 390-392. Serono, PC. 1997. The origin and evolution of dino- Osborn, H.F 1917. Skclotal of 5aur3. Ann. Xeu. Earth Planet. Sci., 25:435-489. , Struti~iornimus,Tyrannosaurus. Wellnhofer, P 1974. Das funfte Skelettexemplar von Liull. Amer Mws. Nat. IIist., 35: 733-771. Arciiaeopter,yz lithographicn Palaeontograpiziea Ostrom, JIi. 1969. Osteology of Deinonychus (A) 147:169-216. antirrhopus, an unusual theropod from the I'ower Xu, X., M. A. Norell, X. Wang, I? Makovicky & X. Wu. Cretaceous of Montana. Bull. Peab0d.y Mus. Nat. 2002. A basal troodontid from tho Early Cret,a- Hisl., 30:l.-165. ceous of China. Nature 415: 780-784.

Recibido: 15-lX-2003 Acevtado: 10-XII-2003