Dinosaur remains from the Arabian subcontinent are exceedingly rare, and those that have been documented manifest indeterminate affinities. Consequently the discovery of a small, but diagnostic, accumulation of elements from Campanian-Maastrichtian (~75 Ma) deposits in northwestern Saudi Arabia is significant because it constitutes the first taxonomically identifiable dinosaur material described from the Arabian Peninsula. The fossils include a series of possible lithostrotian titanosaur caudal vertebrae, and some isolated theropod marginal teeth that share unique character states and metric parameters (analyzed using multivariate statistical methods) with derived abelisaurids – this is the first justifiable example of a non-avian carnivorous dinosaur clade from Arabia. The recognition of titanosaurians and abelisaurids from Saudi Arabia extends the palaeogeographical range of these groups along the entire northern Gondwanan margin during the latest Cretaceous. Moreover, given the extreme paucity of coeval occurrences elsewhere, the Saudi Arabian fossils provide a tantalizing glimpse into dinosaurian assemblage diversity within the region.
Citation: Kear BP, Rich TH, Vickers-Rich P, Ali MA, Al-Mufarreh YA, Matari AH, et al. (2013) First Dinosaurs from Saudi Arabia. PLoS ONE 8(12): e84041. doi:10.1371/journal.pone.0084041
Editor: Ulrich Joger, State Natural History Museum, Germany
Received: March 11, 2013; Accepted: November 20, 2013; Published: December 26, 2013
Copyright: © 2013 Kear et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: Funding for this work was provided by the Saudi Geological Survey. As a standard requirement of their duties, staff from the Saudi Geological Survey participated in data collection, preparation of the manuscript, and the decision to publish.
Competing interests: The authors have declared that no competing interests exist.
Dinosaur fossils are extremely scarce in the Arabian Peninsula and Levant region of the Middle East. Published occurrences include isolated teeth and bones of Cretaceous brachiosaurid (Neocomian) and titanosaurian (Maastrichtian) sauropods from Lebanon  and Jordan  respectively, indeterminate sauropod limb material from Oman (Maastrichtian ), large theropod postcranial elements from Oman (Maastrichtian ) and Syria (Cenomanian or Turonian/Senonian ), and fragmentary ornithopod (Maastrichtian) remains from Oman  and Jordan . The partial skeleton of an enantiornithine bird has also been documented from the Late Cretaceous of Lebanon (Cenomanian ), together with feather inclusions in amber from the Early Cretaceous (Neocomian) of Lebanon  and Jordan . Jacobs et al.  and Schulp et al.  provided accounts of both undefined sauropod body fossils, and sauropod and ornithopod footprints from Jurassic-Cretaceous (Bathonian-Berriasian) strata in Yemen. Avnimelech  additionally described Late Cretaceous (Cenomanian) theropod tracks near Jerusalem.
Virtually nothing has been reported on dinosaurs from Saudi Arabia. Hughes and Johnson ( p. 59, Fig. 11 and in text on p. 60) briefly mentioned a confidential Saudi Aramco report (“Milner, A., N. Morris and P. Jeffery. 1993. Report on Macrofossils from the Kingdom of Saudi Arabia. Natural History Museum, London, Confidential report for Saudi Aramco”) that identified bone fragments of a “sauropod dinosaur, possibly a titanosaurid” from the Adaffa Formation, an Upper Cretaceous unit that crops out in the Midyan Peninsula region along the northeastern coast of the Red Sea (Fig. 1). Grainger ( p. 153) also noted some additional “tentatively confirmed” dinosaur bones, together with other vertebrate remains, collected from the Adaffa Formation in 2004–2008 by a joint team from the Saudi Geological Survey (SGS) and Egyptian Geological Museum. Subsequent appraisal of this material by Kear et al. ,  documented a primarily marine fauna incorporating: indeterminate anacoracid? sharks; actinopterygians − lepisosteids, pycnodontiforms, pachycormids (cf. Protosphyraena) and teleosts (cf. Enchodus sp.); ceratodont lungfish (Ceratodus sp.); bothremydid turtles; dyrosaurid crocodilians; an elasmosaurid plesiosaur; plioplatecarpine mosasaurs and the widespread mosasaurine Prognathodon; as well as a small aquatic varanoid (cf. Pachyvaranus). A few dinosaur bones and teeth were also recovered from the deposit and are presented in this paper. These fossils are important because they represent the first definitive dinosaurian remains described from the Kingdom of Saudi Arabia.
Simplified regional map (top left) with enlargement (bottom) showing distribution of Adaffa Formation outcrops and geographical positioning of the Arabian Peninsula during the Campanian-Maastrichtian (top right). Geological map simplified from  with stratigraphic terminology following .
No permits were required for the described study, which complied with all relevant regulations.
The Adaffa Formation is a thick sequence of cross-bedded, quartz arenite sandstones with basal conglomerates, and upper-most thin marl, siltstone, and fine-grained sandstone layers. It forms the lower-most unit of the Late Cretaceous to Paleogene Suqah Group, a series of pre-Red Sea rift strata that unconformably overly Paleozoic basement rocks in the Usfan region (Jeddah Basin) near Jeddah, and northwards into the Midyan region (Ifal Basin) of far northwestern Saudi Arabia . Detailed stratigraphic assessments ,  and palynological studies indicate an early Campanian−early Maastrichtian age .
The Adaffa Formation vertebrate macrofossils occur in two restricted graben structures, the Aynunah and Sharmah troughs. The individual elements are disarticulated and randomly distributed through thin limonitic beds near the top of the main sandstone sequence. The bone surfaces exhibit extensive surface abrasion (e.g. edge rounding and decortication) consistent with damage by wave action and/or currents prior to burial. This accords with the inferred supratidal marine to fluviatile depositional settings, with coarse clastic input from braided river outlets fed by periodic flash floods .
Results and Discussion
Seven caudal vertebrae from a sauropod (SGS 0188, SGS 0213, SGS 0342, SGS 0366, SGS 0422, plus two additional unregistered fragments), and two theropod marginal teeth (SGS 0061, SGS 0090), were recovered during an exhaustive excavation of a small limonitic sandstone exposure (~10 m2) within the Aynunah Trough, about 11 km northeast of Al Khuraybah ([Fig. 1]; see Hughes and Johnson ( p. 60, Fig. 12 for a photograph of the site). These elements were found intermixed with other vertebrate remnants and numerous wood fragments, presumably sorted by turbulent water action. There was no obvious association between individual skeletal components; although, compatible anatomical positioning, size, ontogentic stage, and taxonomic affinities of at least the dinosaur material suggests derivation from single animals. All of the specimens were accessioned into the Paleontological Collection of the Saudi Geological Survey, Jeddah, Kingdom of Saudi Arabia.
The sauropod vertebrae appear to form a continuous series from the posterior-distal caudal region. Unfortunately, most of the bones are badly weathered and comprise only broken parts of the centra. However, one specimen (SGS 0366 [Fig. 2A−C]) is relatively complete and retains a neural arch. Dimensions of SGS 0366 are: centrum length = 105 mm; centrum width across the anterior articular surface = 66 mm; lateral height of the anterior articular surface = 56.5 mm; maximum vertebral height including neural arch = 133 mm. The recovered centra are all cylindrical in outline and clearly procoelous, a classic feature of titanosaurians . Where discernible, the ventral surface is flat and exhibits raised areas on both the anterior and posterior ends for accommodation of the chevron facets. The neural arch is anteriorly positioned (compatible with titanosauriforms , ) and the prezygapophyses, although broken and heavily weathered, would have projected anterodorsally. The spinoprezygapophyseal laminae are not fused and the prespinal lamina is present as a low, near horizontal ridge. The neural spine is elongate and posteriorly inclined reminiscent of titanosaurian taxa such as Isisaurus and Neuquensaurus . The postzygaphophyses are weakly delineated.
Titanosaurian distal caudal vertebra (SGS 0366) in: A, anterior; B, lateral; and C posterior views. Abelisaurid teeth including: D, crown fragment (SGS 0061) with enlargement of the distal denticles; and maxillary-dentary tooth (SGS 0090) shown in distal (E) and lateral (F) views with enlargements of the distal carina and baso-apical enamel ridges.
Both of the Adaffa Formation theropod teeth are incomplete: SGS 0061 consists of only a sheared sliver, preserving parts of the lateral and distal surfaces, the latter bearing a denticle row [Fig. 2D]; SGS 0090 is a relatively complete crown with worn apex and broken base [Fig. 2E, F]. The tooth outline is narrow compared to its length and height (SGS 0090 crown base width [CBW] = 4.7 mm; crown base length [CBL] = 11.6; crown height [CH] = 17.1 mm; CBW/CBL [CBR] = 0.41). It is also low in profile (CH/CBL [CHR] = 1.47), and nearly triangular in lateral view with the apex positioned close to the centre of the crown base (crown angle [CA] = 82°). The gently convex mesial face is rounded and lacks a carina. Conversely, the distal profile is clearly linear, consistent with the distinctive maxillary-dentary teeth of abelisaurid ceratosaurians . The distal carina is straight and comprises labio-lingually broad denticles (average density [DAVG] = 10.9/5 mm) with basally angled interdental sulci (resembling derived carnotaurines , ). Both the labial and lingual tooth surfaces bear apically converging longitudinal ridges, which are more pronounced distally and occasionally branch towards the base [Fig. 2F]. Similar vertical enamel ridging or fluting has been reported in dromaeosaurids , spinosaurids , and ceratosaurians  including the abelisauroid Masiakasaurus .
The Adaffa Formation dinosaur remains are fragmentary but can be unambiguously referred to typical Late Cretaceous Gondwanan lineages based on discrete phylogenetic character states: Titanosauria  and Lithostrotia , diagnosed by the presence of procoelous caudal centra; and Abelisauridae, characterized by a centrally positioned tooth apex with strongly curved mesial, and straight distal profiles . Baso-apically trending ridges and interdental sulci can also be variably developed in derived forms . However, because some qualitative theropod tooth characters are known to be phylogenetically ambiguous , we conducted a series of morphometric analyses to corroborate our hypothesized affinity for the Adaffa Formation specimens, and to test their proportional similarities relative to other non-avian theropods. Measurements of SGS 0090 and SGS 0061 [Table 1] were added to the most taxon-rich matrix of theropod dental metrics obtainable from the literature  with taxonomic modifications introduced by Smith and Lamanna . Unfortunately, a compatible metric data set was not available for sauropod postcranial elements, preventing quantitative evaluation of affinities; primary compilation of such information from original fossils and/or the literature was also beyond the scope of this paper.
We log10-transformed (see rationalization in Samman et al.  and references therein) the theropod tooth measurements and subjected them to a series of multivariate statistical analyses designed to best accommodate our small sample size and its missing information: (1) a Principal components analysis (PCA), bivariate plots, and a Discriminant analysis (DA) focusing on size correlated variables (CBL, CBW, CH, AL); (2) a parametric Multivariate analysis of variance (MANOVA) and Canonical variates analysis (CVA) utilizing the total specimen data set organized into 10 phylogenetically defined , , , ,  family-level clades [groupings listed in Fig. 3]; (3) Euclidean and Neighbor-joining cluster analyses of all parameters averaged over these same families; and (4), a non-parametric one-way MANOVA (NPMANOVA), coupled with (5) a non-parametric one-way Analysis of similarities (ANOSIM), both manipulating the total data set divided into 14 stratigraphic source unit categories (collated from ). All calculations were conducted in PAST .
Result derived by adding SGS 0090 (green x) to the dental morphometric matrix of Smith et al. . Samples were organized into 10 categories representing theropod family-level clades (see legend). Component axes 1 and 2 depict maximum discrimination in the data set; minimum scatter areas for each group indicated by polygons coded by taxon/sample colour.
(1) PCA, Bivariate Plots, and DA
We used a PCA, bivariate plots, and a DA to visualize the proposed linear relationship  between tooth base dimensions (CBL/CBW) and total crown height (CH), and to ascertain how this might affect our a priori shape-based classification of the most complete Adaffa Formation dinosaur tooth (SGS 0090). The PCA methodology followed Smith et al.  by incorporating CBL, CBW, CBR, CH, CHR, AL, CA, and DAVG (using a standard deviation normalized “correlation” setting for different units of measurement) to yield 67.869% of variance explained by the first principal component, and 13.666% by the second [scatter diagram in Fig. 3]. The first principal component is often thought to reify the size-determined shape vector , and in our analyses derived >0.96 of its correlated variable loading each from CBL, CBW, CH, and AL. Subsequent PCAs alternatively utilizing CBL, CBW, CH, and AL versus CBL, CBW, and CH, returned either 97.858% or 97.972% variance within the first principal component, and placed SGS 0090 exclusively amongst abelisaurids (Majungasaurus + “Indosuchus”) [Fig. 4, 5]. This implies close compatibility in their tooth base-height size parameters as depicted in bivariate plots of CBL/CH [Fig. 6A] and CBW/CH [Fig. 6B]; these also exhibited significant (RMA slope a = 0.91227/a = 1.0176) allometry as reported in other theropods . Discriminant analyses of the same variables with an initial Box’s M test for homoscedasticity (raw data p<1.0223E-14; p<4.1647E-12), likewise classified SGS 0090 with abelisaurids. However, only 66.25%, or 65.63% respectively (a >90% hit ratio is normally considered distinct ), of teeth in the sample could be correctly identified, and there was no significant difference (p<0.001) in multivariate mean (Hotelling’s T2: p<0.3386; p<0.2171). Better compliance was achieved when all variables were examined collectively (as in previous studies , , ), with 80.94% correct classification. Nonetheless, there was still no significant difference between the multivariate means (Hotelling’s T2: p<6.725E-09), inferring that the variances were small in proportion to the distance between these two groups.
SGS 0090 (green x) is placed exclusively within the minimal scatter area (green polygon) of the sampled abelisaurid taxa, Majungasaurus and “Indosuchus”. Axis/symbol equivalencies shown in Fig. 3.
SGS 0090 (green x) is placed exclusively within the minimal scatter area (green polygon) of the sampled abelisaurid taxa, Majungasaurus and “Indosuchus”. Axis/symbol equivalencies shown in Fig. 3.
Both A, CBL/CH; and B, CBW/CH tooth parameters indicate placement of SGS 0090 (green x) exclusively within the minimal scatter area (green polygon) of the sampled abelisaurid taxa, Majungasaurus and “Indosuchus”. Symbol equivalencies shown in Fig. 3.
(2) MANOVA and CVA
To further assess the equality of multivariate means (centroids) across multiple independent samples, and the impact of incorporating variables from both SGS 0090 and SGS 0061, we undertook a MANOVA with enforced Euclidean distance measure and depiction via a CVA [Fig. 7]. The MANOVA proceeded with pairwise comparisons between SGS 0090 + SGS 0061 and abelisaurids (Majungasaurus + “Indosuchus”), Ceratosaurus, Masiakasaurus, Allosaurus, carcharodontosaurids (Acrocathosaurus + Carcharodontosaurus), spinosaurids (Baryonyx + Suchomimus), tyrannosaurids (Gorgosaurus + Daspletosaurus + Tyrannosaurus), troodontids (Troodon + Saurornithoides), and dromaeosaurids (Bambiraptor + Deinonychus + Dromaeosaurus + Velociraptor). None of these taxa were found to be significantly different (p<0.05) from SGS 0090 + SGS 0061 in their tooth metrics. However, the minimum ( = closest equality) squared Mahanalobis distance (D2) of 161.626 units was still returned between SGS 0090 + SGS 0061 and the Majungasaurus + “Indosuchus” centroid (Hotelling’s T2: p<6.53207E-11).
SGS 0061 + SGS 0090 represented by (green x); other symbol equivalencies shown in Fig. 3. Axes 1 and 2 depict maximum discrimination in the data set.
(3) Cluster Analyses
We also employed a series of bootstrapped (1000 replicates) linear Euclidean cluster analyses to visualize the placement of SGS 0090 + SGS 0061 against a distance matrix of values averaged (so as to minimize sensitivity inherent in uneven sample sizes) over non-avian theropod family-level clades [see legend in Fig. 3]. Calculations used an unweighted paired-group average (UPGMA) [Fig. 8A] and Ward’s method, which joins clusters using minimal ingroup variance [Fig. 8B]. These approaches all derived unreliable support (< 50% bootstrap values); however, Larson and Currie  recently reported that metrically compatible Late Cretaceous theropod teeth display marked source unit specificity. We therefore chronostratigraphically constrained our UPGMA to follow stage-level time bins (with temporal ranges for family-level taxa defined using recognized phylogenetic boundaries , , , , ), and subsequently derived a much more robust SGS 0090 + SGS 0061 + abelisaurid grouping (99% bootstrap value [Fig. 8C]). Nevertheless, cross-correlation with Neighbour-joining again failed to generate comparable agglomerations when using stratigraphically unconstrained data [see Fig. 8D].
A, UPGMA; B, Ward’s method; C, chronostratigraphically constrained UPGMA clustering; D, phylogram generated by Neighbour-joining clustering. Node numbering represents bootstrap percentages from 1000 replicates.
To alternatively examine SGS 0090 + SGS 0061 as a locality sample, rather that simply assume taxonomic homogeneity, we differentiated multivariate data points over the entire distance matrix with taxa grouped by their stratigraphic source units. This employed a NPMANOVA with default Bray-Curtis, as well as user specified Euclidean distance measures. Significant difference (p<0.05) was found between SGS 0090 + SGS 0061 and Liliensternus, Ceratosaurus, Masiakasaurus, Allosaurus, Acrocathosaurus, Carcharodontosaurus, Baryonyx, Gorgosaurus, Daspletosaurus, Tyrannosaurus, Troodon, Saurornithoides, Bambiraptor, Deinonychus, and Dromaeosaurus. A minimum F statistic value ( = closest distance) of 0.4586 (Bray-Curtis)/0.5882 (Euclidean) was found for SGS 0090 + SGS 0061 and the derived carnotaurine Majungasaurus, with a strong probability of equality from 10000 permutations (p<0.6106; p<0.559).
As a cross-correlation for the NPMANOVA results, we also calculated an ANOSIM (using Bray-Curtis and Euclidean distance measures) to compare distances both within and between our designated stratigraphic groupings. This derived significant distance (p<0.05) between SGS 0090 + SGS 0061 and Liliensternus, Ceratosaurus, Masiakasaurus, Allosaurus, Acrocathosaurus, Carcharodontosaurus, Baryonyx, Gorgosaurus, Daspletosaurus, Tyrannosaurus, Troodon, Saurornithoides, Bambiraptor, Deinonychus, and Dromaeosaurus. Closest approximation occurred between SGS 0090 + SGS 0061 and abelisaurids, with the minimum positive R value ( = least distance) of 0.02938 (Bray-Curtis)/0.0853 (Euclidean) again indicating nearest placement to Majungasaurus (probability of equality from 10000 permutations: p<0.3756; p<0.2829).
Despite being fragmentary, the Adaffa Formation dinosaur remains are justifiably referable to well-known Late Cretaceous taxa: Titanosauria, the globally dominant group of Campanian-Maastrichtian sauropods , robustly diagnosed by the presence of procoelous caudal centra  (alternatively this has been considered a synapomorphy for the constituent clade Lithostrotia ); and Abelisauridae, whose latest Cretaceous African distribution is substantiated by rare teeth  uniquely possessing a centrally positioned apex with strongly curved mesial, and straight distal profiles . Closely compatible dental morphometry derived using an established data set , ,  and methodologies , , ,  contributes further support for this theropod classification.
The combined evidence of testable phylogentic character states and metric similarities, we believe, provides a rigorous basis for our taxonomic assignments, even when reliant upon a few incomplete specimens. This is important because dinosaur material from the Arabian Peninsula and Levant is otherwise limited to isolated traces, or rare assemblages recognized only from non-diagnostic body fossils ,  and track ways . Given this dearth of co-occurring remains, nothing has yet been gleaned of Arabian dinosaur diversity other than the sympatric presence of indeterminate ornithopods, sauropods, and theropods during the Maastrichtian , . The recovery of demonstrably coeval titanosaurian (possibly lithostrotian) and derived abelisaurid remains in the Adaffa Formation of Saudi Arabia therefore provides the first taxonomic verification of faunal composition within the region. Moreover, it brings to light the only definitively identifiable example of a non-avian theropod dinosaur clade from the Arabian subcontinent, and one that shows closest compatibility with penecontemporaneous faunas in Africa  and Madagascar .
The Arabian Peninsula was contiguous with the main North African landmass during the Late Cretaceous [see Fig. 1], and would have experienced uniform equatorial climates and vegetational regimes . Phylogenetic coherence of the Adaffa Formation dinosaur remains with quintessential northern Gondwanan faunal elements is therefore not surprising. However, the Afro-Arabian record of titanosaurians and abelisaurids is not only extremely poor, but also mainly restricted to the pre-Cenomanian Cretaceous , . Thus the Saudi Arabian fossils, together other finds from the latest Cretaceous (Maastrichtian) of Morocco , , Jordan , and Egypt , provide important evidence of the palaeogeographical ubiquity of these taxa along the northern Gondwanan margin towards the end of the Mesozoic.
This paper is dedicated to the late Dr Yousry Attia (1952–2008), who coordinated recovery and curation of the Adaffa Formation vertebrate remains. Dr Zohair A. Nawab and Dr. Abdullah Attas (Saudi Geological Survey) facilitated financial and logistical assistance, with continuing support for joint research programmes. Maxim Leonov (Palaeontological Institute, Russian Academy of Sciences), Timothy Holland (Melbourne Museum), and Emma Årvestal (Uppsala University) contributed photography and transcription of the morphometric matrix. Ulrich Joger (Academic Editor) and two anonymous reviewers provided constructive comments on the manuscript.
Conceived and designed the experiments: BPK. Performed the experiments: BPK. Analyzed the data: BPK. Contributed reagents/materials/analysis tools: MAA YAAM MAH. Wrote the paper: BPK THR PVR MAA. Participated in research and coordinated field logistics: MAA YAAM AHM AMAM AHN YA MAH.
- 1. Buffetaut E, Azar D, Nel A, Ziadé K, Acra A (2006) First nonavian dinosaur from Lebanon: a brachiosaurid sauropod from the Lower Cretaceous of the Jezzine District. Naturwissenschaften 93: 440–443. doi: 10.1007/s00114-006-0124-z
- 2. Wilson J, Mustafa H, Zalmout I (2006) Latest Cretaceous reptiles from the Hashemite Kingdom of Jordan. Journal of Vertebrate Paleontology Supplement 26: 140A.
- 3. Schulp AS, O’Connor PM, Weishampel DB, Al-Sayigh AR, Al-Harthy A, et al. (2008) Ornithopod and sauropod dinosaur remains from the Maastrichtian A-Khod Conglomerate, Sultanate of Oman. Sultan Qaboos University Journal of Science 13: 27–32.
- 4. Schulp AS, Hanna SS, Hartman AF, Jagt JWM (2000) A Late Cretaceous theropod caudal vertebra from the Sultanate of Oman. Cretaceous Research 21: 851–856. doi: 10.1006/cres.2000.0235
- 5. Hooijer DA (1968) A Cretaceous dinosaur from the Syrian Arab Republic. Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen, Series B 71: 150–152.
- 6. Martill DM, Frey E, Sadaqah RM (1996) The first dinosaur from the Hashemite Kingdom of Jordan. Neues Jahrbuch für Geologie und Paläontologie, Monatshefte 1996: 147–154.
- 7. Dalla Veccia F, Chiappe LM (2002) First avian skeleton from the Mesozoic of northern Gondwana. Journal of Vertebrate Paleontology 22: 856–860. doi: 10.1671/0272-4634(2002)022[0856:fasftm]2.0.co;2
- 8. Schlee D (1973) Harzkonservierte fossile Vogelfedern aus der Untersten Kreide. Journal of Ornithology 114: 207–219. doi: 10.1007/bf01641171
- 9. Kaddumi H (2005) Amber of Jordan: the oldest prehistoric insects in fossilized resin. Amman: Eternal River Museum of Natural History. 168 p.
- 10. Jacobs LL, Murry PA, Downs WR, El-Nakhal HA (1999) A dinosaur from the Republic of Yemen. In: Whybrow PJ, Hill A, editors. Fossil Vertebrates of Arabia. New Haven: Yale University Press. pp. 454–459.
- 11. Schulp AS, Al-Wosabi M, Stevens NJ (2008) First Dinosaur Tracks from the Arabian Peninsula. PLoS ONE 3(5): e2243 doi:10.1371/journal.pone.0002243.
- 12. Avnimelech MA (1962) Dinosaur tracks in the Lower Cenomanian of Jerusalem. Nature 196: 264. doi: 10.1038/196264a0
- 13. Hughes GW, Johnson RS (2005) Lithostratigraphy of the Red Sea region. GeoArabia 10: 49–126.
- 14. Grainger D (2007) The Geologic Evolution of Saudi Arabia. A Voyage Through Space and Time. Jeddah: Saudi Geological Survey 264 p.
- 15. Kear BP, Rich TH, Ali MA, Al-Mufarrih YA, Matiri AH, et al. (2008) Late Cretaceous (Campanian-Maastrichtian) marine reptiles from the Adaffa Formation, NW Saudi Arabia. Geological Magazine 145: 648–654. doi: 10.1017/s0016756808005062
- 16. Kear BP, Rich TH, Ali MA, Al-Mufarrih YA, Matiri AH, et al. (2009) An Upper Cretaceous (Campanian-Maastrichtian) actinopterygian fish assemblage from the marginal marine Adaffa Formation of Saudi Arabia. Cretaceous Research 30: 1164–1168. doi: 10.1016/j.cretres.2009.05.002
- 17. Clark MD (1987) Explanatory Notes to the Geologic Map of the Al Bad Quadrangle, Sheet 28A, Kingdom of Saudi Arabia. Saudi Arabian Deputy Ministry for Mineral Resources Geoscience Map Series GM-81ACscale 1:250,000. 46 p.
- 18. Filatoff J, Hughes GW (1996) Late Cretaceous to Recent Palaeoenvironments of the Saudi Arabian Red Sea. Journal of African Earth Sciences 22: 535–548. doi: 10.1016/0899-5362(96)00035-8
- 19. Curry Rogers K (2005) Titanosauria: a phylogenetic overview. In: Rogers K C, Wilson JA, editors. Sauropods: Evolution and Paleobiology. Berkley: University of California Press. pp. 50–103.
- 20. Salgado L, Coria RA, Calvo J (1997) Evolution of titanosaurid sauropods. I: phylogenetic analysis based on the postcranial evidence. Ameghiniana 34: 3–32.
- 21. D'Emic MD (2012) The early evolution of titanosauriform sauropod dinosaurs. Zoological Journal of the Linnean Society 166: 624–671. doi: 10.1111/j.1096-3642.2012.00853.x
- 22. Curry Rogers K (2009) The postcranial osteology of Rapetosaurus krausei (Sauropoda: Titanosauria) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology 29: 1046–1086. doi: 10.1671/039.029.0432
- 23. Smith JB (2007) Dental morphology and variation in Majungasaurus crenatissimus (Therapoda: Abelisauridae) from the Late Cretaceous of Madagascar. Society of Vertebrate Paleontology Memoir 8: 103–126. doi: 10.1671/0272-4634(2007)27[103:dmavim]2.0.co;2
- 24. Smith JB, Lamanna MC (2006) An abelisaurid from the Late Cretaceous of Egypt: implications for theropod biogeography. Naturwissenschaften 93: 242–245. doi: 10.1007/s00114-006-0092-3
- 25. Currie PJ, Rigby JK Jr, Sloan RE (1990) Theropod teeth from the Judith River Formation of southern Alberta, Canada. In: Carpenter K, Currie PJ, editors. Dinosaur Systematics: Perspectives and Approaches. Cambridge: Cambridge University Press. pp. 107–125.
- 26. Sues HD, Frey E, Martill DM, Scott DM (2002) Irritator challengeri, a spinosaurid (Dinosauria: Theropoda) from the Lower Cretaceous of Brazil. Journal of Vertebrate Paleontology 22: 535–547. doi: 10.1671/0272-4634(2002)022[0535:icasdt]2.0.co;2
- 27. Soto M, Perea D (2008) A ceratosaurid (Dinosauria, Theropoda) from the Late Jurassic-Early Cretaceous of Uraguay. Journal of Vertebrate Paleontology 28: 439–444. doi: 10.1671/0272-4634(2008)28[439:acdtft]2.0.co;2
- 28. Carrano MT, Sampson SD, Forster CA (2002) The osteology of Masiakasaurus knopfleri, a small abelisouroid (Dinosauria: Theropoda) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology 22: 510–534. doi: 10.1671/0272-4634(2002)022[0510:toomka]2.0.co;2
- 29. Wilson J (2002) Sauropod dinosaur phylogeny: critique and cladistic analysis. Zoological Journal of the Linnean Society 136: 215–275. doi: 10.1046/j.1096-3642.2002.00029.x
- 30. Canale JI, Scanferla CA, Agnolin FL, Novas FE (2009) New carnivorous dinosaur from the Late Cretaceous of NW Patagonia and the evolution of abelisaurid theropods. Naturwissenschaften 96: 409–414. doi: 10.1007/s00114-008-0487-4
- 31. Brusatte SL, Benson RBJ, Carr TD, Williamson TE, Sereno PC (2007) The systematic utility of theropod enamel wrinkles. Journal of Vertebrate Paleontology 27: 1052–1056. doi: 10.1671/0272-4634(2007)27[1052:tsuote]2.0.co;2
- 32. Smith JB, Vann DR, Dodson P (2005) Dental morphology and variation in theropod dinosaurs: implications for the taxonomic identification of isolated teeth. Anatomical Record A 285: 699–736. doi: 10.1002/ar.a.20206
- 33. Samman T, Powell GL, Currie PJ, Hills LV (2005) Morphometry of the teeth of western North American tyrannosaurids and its applicability to quantitative classification. Acta Palaeontologica polonica 50: 757–776.
- 34. Holtz TR Jr (2000) A new phylogeny of the carnivorous dinosaurs. Gaia 15: 5–61.
- 35. Carrano MT, Sampson SD (2008) The phylogeny of Ceratosauria (Dinosauria: Theropoda). Journal of Systematic Palaeontology 6: 183–236. doi: 10.1017/s1477201907002246
- 36. Brusatte SL, Sereno PC (2008) Phylogeny of Allosauroidea (Dinosauria: Theropoda): comparative analysis and resolution. Journal of Systematic Palaeontology 6: 155–182. doi: 10.1017/s1477201907002404
- 37. Senter P (2007) A new look at the phylogeny of Coelurosauria (Dinosauria: Theropoda). Journal of Systematic Palaeontology 5: 429–463. doi: 10.1017/s1477201907002143
- 38. Turner AH, Makovicky PJ, Norell MA (2012) A review of dromaeosaurid systematics and paravian phylogeny. Bulletin of the American Museum of Natural History 371: 1–206. doi: 10.1206/748.1
- 39. Weishampel DB, Dodson P, Osmólska H (2004) The Dinosauria. Second Edition. Berkeley: University of California Press 880 p.
- 40. Hammer Ø, Harper DAT, Ryan PD (2001) PAST: Paleontological Statistics Software Package for Education and Data Analysis. Palaeontolgica Electronica 4(1): 1–9.
- 41. Fanti F, Therrien F (2007) Theropod tooth assemblages from the Late Cretaceous Maevarano Formation and the possible presence of dromaeosaurids in Madagascar. Acta Palaeontologica Polonica 52: 155–166.
- 42. McKinney ML (1990) Trends in body−size evolution. In: McNamara KJ, editor. Evolutionary Trends. Tucson: The University of Arizona Press. pp 75–118.
- 43. Buckley LG, Larson DW, Reichel M, Samman T (2010) Quantifying tooth variation within a single population of Albertosaurus sarcophagus (Theropoda: Tyrannosauridae) and implications for identifying isolated teeth of tyrannosaurids. Canadian Journal of Earth Sciences 47: 1227–1251. doi: 10.1139/e10-029
- 44. Hammer Ø, Harper DAT (2006) Paleontological Data Analysis. Oxford: Blackwell Publishing Ltd. 351 p.
- 45. Smith JB, Dalla Vecchia FM (2006) An abelisaurid (Dinosauria: Theropoda) tooth from the Lower Cretaceous Chicla Formation of Libya. Journal of African Earth Sciences 46: 240–244. doi: 10.1016/j.jafrearsci.2006.05.007
- 46. Larson AS, Currie PJ (2013) Multivariate analyses of small theropod dinosaur teeth and implications for paleoecological turnover through time. PLoS ONE 8(1): e54329 doi:10.1371/journal.pone.0054329.
- 47. Mannion PB, Upchurch P (2011) A re-evaluation of the ‘mid-Cretaceous sauropod hiatus’ and the impact of uneven sampling of the fossil record on patterns of regional dinosaur extinction. Palaeogeography, Palaeoclimatology, Palaeoecology 299: 529–540. doi: 10.1016/j.palaeo.2010.12.003
- 48. Mateus O, Jacobs LL, Schulp AS, Polcyn MJ, Tavares TS, et al. (2011) Angolatitian adamastor, a new sauropod dinosaur and the first record from Angola. Anais da Academia Brasileria de Ciéncias 83: 221–233. doi: 10.1590/s0001-37652011000100012
- 49. Pereda Suberbiola X, Bardet N, Larochène M, Bouya B, Amaghzaz M (2004) The first record of a sauropod dinosaur from the Late Cretaceous phosphates of Morocco. Journal of African Earth Sciences 40: 81–88. doi: 10.1016/j.jafrearsci.2004.07.002
- 50. Buffetaut E, Escuillié F, Pohl B (2005) First theropod dinosaur from the Maastrichtian phosphates of Morocco. Kaupia 14: 3–8.