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Theropod Pedal Unguals from the Late Cretaceous (Cenomanian) of Morocco, Africa

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Theropod Pedal Unguals from the Late Cretaceous (Cenomanian) of Morocco, Africa Novas, Dalla Vecchia & Pais: Cretaceous theropods from Africa 167 Rev. Mus. Argentino Cienc. Nat., n.s. 7(2): 167-175, 2005 Buenos Aires, ISSN 1514-5158 Theropod pedal unguals from the Late Cretaceous (Cenomanian) of Morocco, Africa Fernando E. NOVAS1,2, Fabio DALLA VECCHIA3 & Diego F. PAIS1 1CONICET - Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Av. Angel Gallardo 470, Buenos Aires (1405), Argentina. 2 E-mail: [email protected]. 3Museo Paleontologico Cittadino Via Valentinis 134 I-34074 Monfalcone, Gorizia, Italia. Abstract: Two different theropod pedal unguals from the Upper Cretaceous (Cenomanian) of Tafilalt, Morocco are described. One of them belongs to a slender kind of abelisauroid theropod. Comparison with other members of this group reveals that abelisauroid unguals show high morphological diversity in congruence with what is known on other parts of the skeleton. Another large-sized ungual resembles that described as “Spinosaurus B” by Stromer (1934), and is here referred with caution to Theropoda, although ignoring to which theropod lineage it belongs. Comparisons between northern (e.g., Sahara, Africa and Brazil) and southern (e.g., Patagonia) Gondwanan Cretaceous dinosaur faunas reveal some differences leading to the conclusion that Gondwanan faunas were not uniform across this supercontinent. Key words: Unguals, Theropods, Cretaceous, Africa. ____________ Current knowledge of theropod dinosaurs 2004), and several Aptian specimens eventually from the Upper Cretaceous of Africa is decep- corresponding to a new member of Spinosau- tively fragmentary and taxonomically confuse. ridae, Suchomimus tenerensis (Sereno et. al. Specimens described by the German paleon- 1998; however, see Sues et al., 2002, for a differ- tologist Ernest Stromer from Cenomanian beds ent view on the systematic of this theropod). of Egypt, were destroyed during World War II. Among the variety of dinosaur remains found Thus the only source of information available in Cenomanian beds of Northern Africa, theropod from outstanding discoveries such as Spino- ungual phalanges have been frequently recovered saurus, Carcharodontosaurus, and Bahariasau- (e.g., Stromer, 1934; Rauhut, 1995; Russell, 1996). rus relays solely on Stromer´s monographs (e.g., Similarly to isolated teeth, pedal ungual pha- Stromer, 1915, 1925, 1931, 1934) and some works langes may constitute a useful tool for the recog- by French paleontologists (e.g., Deperet & nition of different dinosaur taxa in poorly pre- Savornin, 1927). Later papers devoted to Creta- served faunal assemblages. For example, abeli- ceous theropods from Africa were published by sauroid unguals are quite distinctive and their Lavocat (1954) and Lapparent (1960), but the isolate finding may prove the presence of this described material consists of fragmentary bones dinosaur clade in Cretaceous theropod assem- with poor phylogenetic information. More re- blages (e.g., Novas & Bandyopadhyay, 2001). Al- cently, Rauhut & Werner (1995), Rauhut (1999), though unguals offer valuable anatomical infor- Russell (1996), and Taquet & Russell (1998) re- mation, few comprehensive comparative studies ported isolated remains of theropods of different exist on these elements. Unfortunately, available affiliations (e.g., Deinonychosauria, Spinosau- knowledge on the morphological variations ridae, Abelisauridae), which reveal a wide mor- among different reptile clades with large-size phological disparity of African theropods. members (e.g., crocodiles, ornitischian, and By far, the most significant theropod findings theropod dinosaurs) collected from Aptian to from Late Cretaceous beds are those reported by Turonian beds, complicate the taxonomic assign- Sereno and colleagues from Morocco and Niger, ment of such isolated pedal elements. who described more complete cranial and In the present paper we describe the anatomy postcranial remains of the Cenomanian carcharo- of some theropod pedal unguals collected in the dontosaurid Carcharodontosaurus saharicus Upper Cretaceous beds of Southern Morocco, of- (Sereno et al., 1996) and the abelisauroids Rugops fering anatomical basis for the taxonomic refer- primus and Deltadromeus agilis (Sereno et al., ral of the studied specimens. We also want to call 168 Revista del Museo Argentino de Ciencias Naturales, n. s. 7 (2), 2005 the attention about some topical aspects of Afri- chelonians. Such fossil association is in agree- can theropod taxonomy, mainly concerning with ment with that recovered from the dinosaur-bear- the specimen originally named “Spinosaurus B” ing rocks of both Tafilalt and Kem Kem regions (Stromer, 1934), as well as to speculate about Russell (1996) reported the Cretaceous theropod paleobiogeography of Gondwana. stratigraphy of the Tafilalt escarpment East and South of Erfoud described by Joly (1962). A lower Geographical and geological provenance unit named “Grès rouges infracénomaniens”, the of studied specimens one which yields fossil remains of dinosaurs, The theropod unguals here described were crocodiles and fishes, occurs above Paleozoic purchased from fossil dealers of Erfoud (South- (Carboniferous) rocks. It is composed mainly of ern Morocco) (S. Piccini, pers. comm.) and be- sandstone deposited in a continental to deltaic long to the private collection of Dr. Stefano environment and in some places is more than 200 Piccini, Torreano di Cividale del Friuli, Udine m thick. It is overlain by lagoonal or coastal plain province, Italy. These specimens will be hopefully beds (i.e., the “Marnes versicolores à gypse”; Joly, deposited in a paleontological museum that the 1962) which could reach a thickness of 100-200 Geofin company has planned to create in the fu- m. The sequence is topped by the frankly marine ture near Cividale del Friuli. Nevertheless, casts “Calcaire cénomano-turonien”, a limestone unit of the studied specimens are deposited in the that contains ammonites, as Neolobites vibra- Museo Paleontologico Cittadino of Monfalcone, yanus, and represents the great Late Ceno- Italy. manian marine transgression. A similar sequence Considerable amount of fossils from Tafilalt is found also in the Kem Kem (Sereno et al.,1996). was collected by local inhabitants and fossil deal- Here the sequence comprised between the ers, currently forming part of private collections. Paleozoic and the Late Cenomanian limestone is Some of these specimens, however, became avail- informally named “Kem Kem beds”, and is di- able for scientific study: Russell (1996) described vided in a lower sandy unit, and an upper unit several dinosaur specimens which are deposited where mudstone is common, both deposited in in The Natural History Museum, London, and deltaic environments and preserving dinosaur the Canadian Museum of Nature, Ottawa. Also, remains (Sereno et al.,1996). Kellner & Mader (1996, 1997), Mader & Kellner According to their stratigraphic position the (1999), and Wellnhofer & Buffetaut (1999) de- “Grès rouges infracénomaniens” cannot be scribed pterosaur and dinosaur remains from the younger than Late Cenomanian. They are usu- same localities housed in paleontological insti- ally considered to be Albian, Cenomanian or tutions of Europe and North America. Although Albian-Cenomanian in age (e.g., Taquet, 1976; specimens are biased by inadequacies regarding Jacobs et al., 1996; Sereno et al., 1996; Russell, both the exact geographic and stratigraphic prov- 1996). Sereno et al. (1996) dated the fossiliferous enances, they are still useful for anatomical levels of Kem Kem as Cenomanian based on the analysis. elasmobranch association. The ungual phalanges Specimens here described probably come from here described come from the “Grès rouges the Tafilalt and Kem Kem regions at the north- infracénomaniens”, and are accordingly inter- ern margin of the Sahara desert. Whereas the preted as Cenomanian. Kem Kem region is far south and difficult to reach, Erfoud occurs in the Tafilalt. Many out- Abbreviations. BMNH R, Natural History crops yielding scattered dinosaur remains can be Museum, London, England; MPCA, Museo Pro- reached easily from this town and some are quar- vincial “Carlos Ameghino”, Cipolletti, Río Negro, ried from sand by local people (F.M. Dalla Vecchia, Argentina; MPCM, Museo Paleontologico pers. obs.). Thus it is much more probable that Cittadino di Monfalcone, Gorizia, Italy; MPEF- the dinosaur remains sold in Erfoud come from PV, Museo Paleontológico “Egidio Feruglio”, the close and easy to reach Tafilalt outcrops Trelew, Chubut, Argentina. rather than from the southern Kem Kem ones. Also the fossils described by Russell (1996) were DESCRIPTION OF SPECIMENS collected and purchased by inhabitants of the Tafilalt. Other fossils in the Piccini’s collection Abelisauroid pedal ungual (MPCM 13573; and from the same source are mainly teeth re- Fig. 1). This ungual, presumably belonging to ferred to Carcharodontosaurus, Spinosaurus, digit IV of left foot, is long and slender, and meas- crocodylomorphs, sauropods, pterosaurs, fishes ures nearly 7cm along its dorsal margin. It is (e.g., Lepidotes, Onchopristis, Hybodus), as well arched (presumably medially), with the lateral as some bones belonging to crocodylomorphs, and surface strongly convex and the medial surface Novas, Dalla Vecchia & Pais: Cretaceous theropods from Africa 169 almost flat. As a result of this asymmetry, the It is slightly curved along its dorsal margin, and medial surface of the ungual is also exposed its ventral surface is flat, thus the ungual results dorsally. Both lateral
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