anteriorly beyond the anterior margin of the neural canal. The postzygapophyses are long and bear very prominent epipophyses that overhang the postzygapophysis posteriorly, with thin epipophyseal laminae that connect with the posterior aspect of the spinal process. In "Wirbel a" these laminae connect to a roof-like structure of a posterior (spinopostzygapophyseal) fossa which "makes the neural arch appear to have been furnished with cavities" *Stromer, 1915:* 13; translated from German). The neural spine itself is differently developed in "Wirbel a" and "Wirbel b," respectively. In "Wirbel a," the neural spine rises from the entire length of the roof of the neural canal and extends beyond the spinopostzygapophyseal fossa. It emerges vertically for 3.5 cm, and then inclines posterodorsally; its dorsal part is broken off. In "Wirbel b," the anterior edge of the spinal process seems to have been connected to the prezygapophyses by low, dorsally concave spinoprezygapophyseal laminae, above which this edge becomes vertically oriented. The posterior edge is vertically oriented from its base. The neural spine covers the posterior 8 cm of the neural arch length.

Stromer tentatively suggested "Wirbel a" to be an axis, and "Wirbel b" to be a mid-cervical. However, the identification of "Wirbel a" as axis is most probably wrong, as this vertebra has a large, dorsomedially facing and anteriorly projecting prezygapophysis, whereas axial prezygapophyses in theropods are usually developed as small, laterodorsally facing facets on the dorsal surface of the anterior end of the neural arch (e.g., *Madsen, 1976*). Furthermore, according to the measurements and figures given by *Stromer (1915)*, this vertebra was approximately as large as the supposed mid-cervical "Wirbel b," which would also be highly unusual. In comparison with *Baryonyx* (*Charig & Milner, 1997*) and *Ichthyovenator*, this neural arch might represent the third cervical vertebra. Characters in favour of this interpretation include the anteroposteriorly rather short neural arch and the posteriorly inclined neural spine with laterally flaring spinopostzygapophyseal laminae, which resembles the axial neural spine. In *Baryonyx* especially the neural spine of the third cervical closely resembles that of the axis (*Charig & Milner, 1997*). The photograph of the original *Spinosaurus* material shows that the vertebral centrum was strongly damaged, which, together with the extensive spinopostzygapophyseal laminae of the neural spine (as they are often found in the axis of basal theropods; e.g., *Welles, 1984*: Fig. 8) might have led Stromer to assume that this vertebra represented the axis. As for Stromer's "Wirbel b," we agree that this element represents a mid-cervical, based on the structure of the neural arch, mainly the high and vertical neural spine. The vertebral centrum is only slightly longer than high, resembling the condition in C5, but unlike the relatively much longer C6 and C7 of *Ichthyovenator*. Thus, this element most probably represents C5, although an identification as C4 cannot be completely excluded.

From the descriptions summarized above, the drawings provided by *Stromer (1915)*, and the photograph of the material, several important differences with *Sigilmassasaurus* can be noticed. First, Stromer specifically noticed that the vertebrae did not have ventral keels, whereas such structures are present already in the mid-cervicals of *Sigilmassasaurus* and are especially well-developed in posterior cervicals. Likewise, a posteriorly positioned, triangular ventral platform, which is prominently developed in the mid-cervicals of
*Sigilmassasaurus* (including the centrum of the possible C5 BSPG 2011 I 117) and clearly visible in lateral view (see above) is not mentioned by Stromer, nor are there any indications for such a structure in his figure of “Wirbel b” (*Stromer, 1915*: Table 1, Fig. 2) or the photograph. There is furthermore no indication of additional deep depressions or foramina on the posterior part of the lateral side of the centrum, as described by *Stromer* (1915) for “Wirbel b” and clearly visible in his illustration (*Stromer, 1915*: pl. 2, Fig. 2) and the only existing photograph of this element (*Smith et al., 2006*: Fig. 3) in any of the vertebrae referred to *Sigilmassasaurus*. Importantly, the epipophyses of both “Wirbel a” and “Wirbel b” are strongly developed and considerably overhang the postzygapophyses posteriorly (although the tip is broken in “Wirbel b”), which is not the case even in the most anterior positioned cervical vertebrae known of *Sigilmassasaurus* (the probable C4 NHMUK PV R 16427). As it is very unlikely that strongly pronounced epipophyses are present in C3 and C5, but not in C4 and from C6 onwards, this is a significant difference. Furthermore, the probable C5 of *Spinosaurus aegyptiacus* has a vertical, anteroposteriorly rather extensive and high neural spine, similar to the condition in the non-*Sigilmassasaurus* spinosaurid vertebra BSPG 2006 I 57. As the neural spine of the probable C4 of *Sigilmassasaurus* (NHMUK PV R 16427) is rather short and posteriorly inclined, and posterior cervical neural spines in this taxon are low and spike-like, such a marked variation in spine morphology within a single taxon also seems rather unlikely. Therefore, as far as comparisons are possible, the type and referred material of *Sigilmassasaurus* differs considerably from cervical material of the original specimen of *Spinosaurus aegyptiacus*. As the material also does not show any uniquely shared synapomorphies, we prefer to keep *Sigilmassasaurus* and *Spinosaurus* as distinct taxa.

## The ‘neotype’ of *Spinosaurus aegyptiacus*

In a recent paper, *Ibrahim et al. (2014a)* designated a neotype for *Spinosaurus aegyptiacus* (the holotype of which was destroyed in WWII) and argued that “*Spinosaurus* B,” *Sigilmassasaurus brevicollis*, and *Spinosaurus maroccanus* are referable to the former taxon. As this nomenclatorial act is relevant to the question of the taxonomic and systematic affinities of *Sigilmassasurus*, we offer here some comments on the designation of this neotype. Unfortunately, the specimen has so far been briefly described and poorly documented, so that the following comments should be regarded as tentative, pending a more comprehensive description of the material. Two of us (SWE, OWMR) have seen casts of the ‘neotype’ at the University of Chicago. As detailed above, we do not accept the synonymy of *Spinosaurus aegyptiacus* and *Sigilmassasaurus* (including *Sigilmassasaurus brevicollis* and *Spinosaurus maroccanus*), but there are further considerations that lead us to reject the specimen described by *Ibrahim et al. (2014a)* as neotype for *Spinosaurus aegyptiacus*.

## Association of remains of the ‘neotype’

As acknowledged by (*Ibrahim et al., 2014a*, suppl. information), the allegedly associated skeleton designated as neotype was largely not excavated by the authors, but acquired from a local collector. More specifically, *Cau (2014*; http://theropoda.blogspot.co.uk/
2014/09/spinosaurus-revolution-episodio-ii-ode.html) noted that parts of the specimen (though it was not specified which parts) were purchased in 2008 by the University of Casablanca, whereas others were acquired in 2009 by the Museo di Storia Naturale in Milan. According to *Ibrahim et al. (2014a)*: SI, p. 6) the authors only subsequently located the collector, who showed them to the supposed locality where “complete excavation of the site by NI, PCS, CDS, DMM, SZ and colleagues resulted in the recovery of many additional pieces belonging to the neotype“ (again, these remains were not specified). Thus, unfortunately, there is no information on the original association of the remains, nor is there additional information on the locality. As most vertebrates in the ‘Kem Kem beds’ are found in multitaxonomic bone beds (*Cavin et al., 2010*), such information is crucial to evaluate if these remains may really pertain to a single individual. Even if it can be shown beyond a doubt that all of this material came from a single locality, it would still remain to be demonstrated that it represents a single individual. Potential evidence for association of the remains comes from the fact that the vertebrae included in this specimen are of matching size and, in the case of comparable elements (different dorsal vertebrae) matching morphology, and this is also true for the left and right femora and tibiae (S Evers & O Rauhut, pers. obs., 2015). However, it must be noted that local collectors in Morocco and fossil dealers often sort remains acquired from different sources according to fitting size and morphology (U Leonhardt, pers. comm., 2015), and an important question is, of course, if the vertebrae and the pelvic and limb elements represent the same individual.

The proportions of the new remains, specifically the disproportionally small pelvic and hindlimb remains, were used by *Ibrahim et al. (2014a)* to suggest very unusual leg proportions in *Spinosaurus*, noting that these unusual proportions are also found in the material of “*Spinosaurus* B,” thus allegedly supporting the association. As outlined below, however, there are significant anatomical differences between the appendicular remains of the ‘neotype’ of *Spinosaurus aegyptiacus* and the remains described as “*Spinosaurus* B,” so unless one assumes that these specimens represent closely related taxa with very similar proportions, but differences in limbbone morphology (for which there is no independent evidence), this coincidence in proportions is of doubtful value to prove association. As noted above, *Stromer (1934)* did not provide any evidence for original association of the remains described as “*Spinosaurus* B,” other than that they were found at the same spot (which would also be the case for non-associated materials resulting from a bone bed). However, it is striking that in both cases there is a set of matching vertebrae on the one hand, and a set of matching limb elements on the other hand.

## Anatomical considerations

*Ibrahim et al. (2014a: Fig. S2)* provided a figure showing the supposed close similarity of the material of the proposed neotype to the remains described as *“Spinosaurus B”* by *Stromer (1934)*. However, no specific characters linking the two specimens were noted, and despite some superficial similarities, there are a number of significant differences, which make a referral of these remains to a single taxon questionable. It should be noted that although the figure claims to be a comparison between the ‘neotype’ and *“Spinosaurus B,”* not all the material figured seems to pertain to the ‘neotype’ material (FSAC-KK 11888); no
cervicodorsal vertebra is indicated in Fig. S3 of *Ibrahim et al. (2014a)*, nor is such a vertebra listed in the list of materials for this specimen (Table S2), yet Fig. S2C clearly shows such an element. A cervicodorsal vertebra is also not among the casts of the ‘neotype’ kept at the University of Chicago (S Evers & O Rauhut, pers. obs., 2015). The figure caption suggests that the vertebra shown in Fig. S2C might instead be material used for the skeletal reconstruction for Fig. S3 (*Ibrahim et al., 2014a*). As no specimen numbers are given for the vertebrae shown in Fig. S2, their identity is unclear, but this cervicodorsal vertebra at least does not seem to belong to the ‘neotype’ material. Cervical vertebrae reported to belong to FSAC-KK 11888 are an axis and C7 (*Ibrahim et al., 2014a*, Table S2), so comparisons to “*Spinosaurus B*” are impossible, as the latter did not preserve these vertebral positions. Comparisons of dorsal vertebrae of “*Spinosaurus B*” and the ‘neotype,’ on the other hand, must be based on measurements given. Even the supposedly similar proportions of the limb bones of “*Spinosaurus B*” and FSAC-KK 11888 in comparison with dorsal vertebral elements are not too close: the allegedly 8th dorsal vertebra of the latter taxon is 26.9% of the length of the tibia, wheras the ratio of a posterior mid-dorsal to tibia length in “*Spinosaurus B*” is 23.3%. Though both ratios would indeed indicate extremely short hindlimbs, this difference of almost 4% is comparable to that found in theropod taxa with greatly different proportions, such as *Allosaurus* (12.3%; Gilmore, 1920) and *Elaphrosaurs* (15.6%; Janensch, 1925), and much greater than that in some phylogenetically disparate taxa, such as *Elaphrosaurus* and *Sinraptor* (15.2–15.3%; Currie & Zhao, 1993).

For non-vertebral material that does belong to the ‘neotype’ (FSAC-KK 11888), the
limited comparisons that can be based on the figures provided by *Ibrahim et al. (2014a)*
with the descriptions and figures provided by *Stromer (1934)* show numerous differences.
Apart from differences that might be attributable to different positions within the skeleton
(e.g., lack of collateral ligament grooves in pedal phalanges, less strongly curved pedal
ungual, etc.), there are important differences in the limb bones.

In the distal femur of “*Spinosaurus B*,” the posteriorly projecting crista tibiofibularis is broken off, but the proximodistal length of its base is less than 75% of the distal width of the femur, as opposed to more than 100% in FSAC-KK 11888. Likewise, the proximodistal expansion of the medial condyle is much greater in the latter specimen than in 1922 X 45. An unusual feature of the femur of “*Spinosaurus B*” is a small, posterodistally pointing tubercle in the intercondylar groove, which has not been described explicitly by Stromer, but is clearly visible in both the posterior and distal views of the specimen (*Stromer, 1934*: pl. 1, Figs. 13B and 13D). Such a tubercle is absent in the femur figured by *Ibrahim et al. (2014a)*: Fig. S2A). Furthermore, the lateral expansion of the lateral condyle beyond the crista tibiofibularis is much more pronounced in 1922 X 45 than in FSAC-KK 11888, and its medial side has a marked longitudinal depression (visible in Stromer’s Figs. 13A and 13D on his plate 1), resulting in the posterolateral edge of the bone forming a sharp ridge. Such a morphology is not present in FSAC-KK 11888, but the medial side is convex anteroposteriorly (*Ibrahim et al., 2014a*: Fig. S2A). It is also conspicuous that *Stromer (1934)* did not mention anything unusual about the femoral shaft of “*Spinosaurus B*,” although only the distal end of the bone is preserved, exposing a cross-section of the shaft.
Given that he was aware that theropods usually have hollow limb bones (he comments on this e.g., in his description of *Carcharodontosaurus*; Stromer, 1931), but in FSAC-KK 11888, the medullary cavity is almost completely closed (Ibrahim et al., 2014a), this seems at least odd (one might argue that Stromer's plate 1, Fig. 13B shows a thin femoral cortex at the proximal break, although this might be over-interpreting the images). Although there is certainly some possible individual variation in the morphology of the distal femur, these comparisons show that there are substantial differences between the two specimens, and no shared derived characters or a unique character combination supporting the referral to a single taxon are obvious. Given the unusually proximodistally elongate posterior crests (crista tibiofibularis and medial condyle) that are present in both femora of FSAC-KK 11888, but not in "*Spinosaurus* B," this might be taxonomically significant.

The same is true for the tibia. According to the measurements given by Stromer (1934: 16), the width-depth ratio of the tibia at mid-shaft is 1.13 for both the right and left tibia of 1922 X 45, whereas it is 1.56 in FSAC-KK 11888 (Ibrahim et al., 2014a: Table S2). This difference in shaft proportion is quite remarkable, as it is larger than that between "*Spinosaurus* B" and most other theropods. For example, this ratio is 1.07 in *Ceratosaurus* (Madsen & Welles, 2000), 1.06 in a tibia referred to *Megalosaurus* (Stromer, 1934), 1.10 in *Piatnitzkysaurus* (PVL 4073), 1.45 in *Sinraptor* (Currie & Zhao, 1993), 1.22 in *Neovenator* (Brusatte, Benson & Hutt, 2008) and *Elaphrosaurus* (Janensch, 1925), and 1.29 in *Acrocanthosaurus* (Stovall & Langston, 1950), and only coelurosaurs have ratios similar to or larger than that of FSAC-KK 11888 (e.g., 1.51 in *Gorgosaurus* Lambe, 1917 (Lambe, 1917) and *Albertosaurus* Osborn, 1905 (Carr, Williamson & Schwimmer, 2005); approximately 2 in *Nothronychus* Kirkland & Wolfe, 2001 (Zanno et al., 2009)). On the other hand, the distal end is considerably more expanded in the Egyptian specimens than in the 'neotype,' with the ratio between length and distal transverse width being 4.61 and 4.65 in the former, but 5.57 in the latter. As the mid-shaft is thus more anteroposteriorly compressed in FSAC-KK 11888, but the distal end is relatively narrower transversely, these proportional differences cannot be explained by compression. Likewise, all other comparable proportions between the Egyptian and Moroccan specimens are also different, and these differences are as large or larger than between the tibiae of "*Spinosaurus* B" and other theropod taxa, so it is unlikely that they represent intraspecific variation.

Apart from these differences in proportion, the distal end of the tibiae of "*Spinosaurus*
B" and FSAC-KK 11888 also show anatomical discrepancies. The most conspicuous of
these are found in the distal ends of the bones. In 1922 X 45, the lateral side gradually
and significantly expands distally, forming a large lateral malleolus that is triangular in
outline in anterior view (Stromer, 1934: pl. 1, Fig. 14A). In contrast, FSAC-KK 11888
has an only moderately expanded lateral malleolus with a slightly convex lateral outline
Ibrahim et al., 2014a: Fig. S2F). Furthermore, Stromer (1934: 17) noted that the medial
malleolus was "almost rectangular" (this malleolus seems to be damaged in the element
figured by Stromer), whereas it forms a tapering, medially rounded structure in FSAC-KK
11888. Although several other differences are obvious from the figures (e.g., in the shape
and extent of the facet for the ascending process of the astragalus and the straight versus
curved tibial shaft), these comparisons show that there are significant differences and no
diagnostic shared characters.

Thus, there is reason to assume that at least the limb elements of "*Spinosaurus* B" and the
specimen from Morocco do not represent the same taxon.

Taxonomic and formal considerations

Even if one accepts the association of the proposed neotype of *Spinosaurus aegyptiacus*,
and the extremely short proportions and similarities with “*Spinosaurus* B” as evidence
that both specimens represent the same taxon, the question remains, which taxon is
represented by these specimens. As demonstrated above, there are several differences
between the vertebrae of *Spinosaurus aegyptiacus* (as described by *Stromer, 1915*) and
*Sigilmassasaurus maroccanus*, indicating that these remains represent different taxa, and
there is also evidence that more than one spinosaur taxon is present in the ‘Kem Kem
beds’ (see also *Richter, Mudroch & Buckley, 2013*). As noted above, the anterior dorsal
vertebra figured by *Stromer* (1934: pl. 1, Fig. 2) is very similar to that described for
*Sigilmassasaurus*, indicating that these remains represent the latter taxon. On the other
hand, the proposed neotype includes neural spines that have a basal expansion (*Ibrahim
et al., 2014a*: Fig. 2E), as it is the case in the holotype of *Spinosaurus aegyptiacus* (*Stromer,
1915*), but not in the dorsal vertebrae known for “*Spinosaurus* B,” as specifically pointed
out by *Stromer* (1934: 22). Thus, if one accepts the association of the material of FSAC-KK
11888 and its identity with “*Spinosaurus* B,” the question remains whether these specimens
represent *Spinosaurus aegyptiacus*, *Sigilmassasaurus brevicollis*, or a further, unnamed taxon
of spinosaur. Examination of a cast of the C7 of the ‘neotype’ at the University of Chicago
by two of us (SWE & OWMR) showed that this vertebra has features incompatible with
*Sigilmassasaurus*. The vertebra of FSAC-KK 11888 shows centroprezygapophyseal fossae
with relatively sharp lateral and dorsal borders, well-developed interpostzygapophyseal
laminae, and lacks a ventral triangular plateau or keel.

This leads to the final objection to the neotype designation by *Ibrahim et al. (2014a)*. As
outlined by these authors *Ibrahim et al., 2014a*: supplements p. 6–7), the ICZN requires
several conditions to be met for a neotype designation. We note that several of these
conditions are not met with the designation of FSAC-KK 11888: the secure identification
of the proposed neotype as the same taxon as the holotype, an exceptional need for the
designation of a neotype, and the geographical proximity of the locality of the neotype
to the original type locality. The first objection is clear from the different considerations
on association, anatomy, and taxonomy of the specimen presented above. As for an
exceptional need for a neotype, it is clear that the holotype of *Spinosaurus aegyptiacus* was
destroyed in WW II, but the material was relatively well-described and figured by *Stromer*
(1915). Both the descriptions and the figures provided by Stromer indicate a number of
potentially autapomorphic characters, such as a change from very large anterior teeth to
minute middle teeth to again large posterior teeth in the dentary (*Stromer, 1915*: pl. 1, Fig.
12B), an extremely enlarged, anteroventrally open anterior myliohyoid foramen in the
splenial (*Stromer, 1915*: pl. 1, Fig. 6), and the strong, rounded expansion at the base of the
neural spines (*Stromer, 1915*: pl. 1, Figs. 17–19, pl. 2, Figs. 3–5). Even if there might be some
doubt about the uniqueness of some of these characters, such as the basal expansion of the neural spines (see above), the identity of *Spinosaurus aegyptiacus* can clearly be established from the combination of numerous unusual characters, based on Stromer's description and figures. Thus, we do not see an exceptional need for a neotype designation.

Concerning the proximity of the locality of the proposed neotype to the original type locality, the distance of the Kem Kem area in Morocco from the Baharyia Oasis in Egypt is roughly 3,200 km in a straight line. Apart from the geographic distance, it is somewhat unclear in how far the fauna from the Baharyia Oasis is directly comparable to that of the Kem Kem compound assemblage. Although great similarity exists on higher systematic levels (see Cavin et al., 2010), only few shared species are actually present, especially in tetrapods (contra Le Loeuff et al., 2012). In crocodiles, for example, many forms are similar and might represent sister taxa, but no shared species are present (see Larsson & Sues, 2007; Sereno & Larsson, 2009; Holliday & Gardner, 2012). In dinosaurs, the only other taxon said to be present in both the Baharyia Oasis and the 'Kem Kem beds' is *Carcharodontosaurus saharicus* (Sereno et al., 1996). The syntypes of this taxon are two isolated teeth from the (?)Albian of the area around Timimoun, western Algeria (*Depéret & Savornin, 1927*), which are now seemingly lost (see *Brusatte & Sereno, 2007*), so *Brusatte & Sereno* (2007) proposed an almost complete skull from the 'Kem Kem beds' area as neotype. *Stromer* (1931) described a fragmentary skeleton from Baharyia also as *Carcharodontosaurus saharicus*, due to the similarity of the teeth to those described by *Depéret & Savornin* (1927). However, teeth with the characteristics described by *Depéret & Savornin* (1927) are also found in other carcharodontosaurid taxa (see *Brusatte & Sereno, 2007*), and no detailed comparison of the skull from the 'Kem Kem beds' with the few skull elements recovered by *Stromer* (1931) from Baharyia (which are also lost) has ever been presented. Thus, it remains to be shown that the latter remains are really conspecific with the specimen from the 'Kem Kem beds,' or if they might represent closely related, but separate species. Apart from *Carcharodontosaurus* and *Spinosaurus*, three additional nominal species of dinosaurs are known from Baharyia, the theropod *Bahariasaurus ingens*, and the sauropods *Aegyptosaurus aegyptiacus* *Stromer, 1932* and *Paralatitan stromeri* Smith et al., 2001 (*Stromer, 1932*; *Stromer, 1934*; Smith et al., 2001); none of these taxa have been identified from the 'Kem Kem beds.' Likewise, none of the other nominal dinosaur species in the 'Kem Kem beds,' including the theropod *Deltadromeus agilis*, the probable carcharodontosaurid *Sauroniops pachytholus* Cau, *Dalla Vecchia & Fabbri, 2013*, and the sauropod *Rebbachisaurus garasbae* Lavocat, 1954 (*Lavocat, 1954*; *Sereno et al., 1996*; Cau, *Dalla Vecchia & Fabbri, 2013*), has been reported from Baharyia. Thus, although similar in general taxonomic composition, there is actually little overlap on specific level between the two localities, making a neotype designation from such a geographically distant locality dubious.

**Synonymy of *Sigilmassasaurus* with *Carcharodontosaurus saharicus***

Soon after it was proposed as a new taxon, *Sigilmassasaurus* was suggested to be a subjective junior synonym of *Carcharodontosaurus* (Sereno et al., 1998; *Brusatte & Sereno, 2007*). This taxonomic opinion was partly based on a proposed overlap between associated material of
Carcharodontosaurus described by Stomer in 1931 as 1922 X 46, and the material *Stromer* (1934) described as "*Spinosaurus B*" (see *Sereno et al., 1996*), which has commonly been interpreted to be material of *Sigilmassasaurus*. The specimen of *Carcharodontosaurus* (1922 X 46) described by *Stromer* (1931) included three cervical vertebrae, of which "Halswirbel b" is the only detailed described and figured postaxial vertebra, allowing comparison to *Sigilmassasaurus* vertebrae. However, the vertebra in question shows significant differences to vertebrae of *Sigilmassasaurus*. Measuring 88 mm across the anterior articular surface of the centrum and 100 mm in length, the centrum of the vertebra is slightly longer than wide. Also, the width–height ratio of "Halswirbel b" equals 1.3, which is much lower than the ratios of >1.5 used to identify *Sigilmassasaurus* (*Russell, 1996; McFeeters et al., 2013*). These observations do not match the morphology seen in the posterior cervicals and anterior dorsals of *Sigilmassasaurus*, to which this material was compared by *Sereno et al.* (1996). Furthermore, "Halswirbel b" was originally identified as an anterior cervical by *Stromer* (1931), and some features like the relative offset between anterior and posterior interarticular facets suppot this identification. Accordingly, comparisons between the "Halswirbel b" of *Carcharodontosaurus* and posterior vertebrae of *Sigilmassasaurus* are inadequate. In comparison with more anterior cervical vertebrae of *Sigilmassasaurus*, such as CMN 50791 or BSPG 2011 I 117, the most striking difference is the extreme shortness of the vertebra of *Carcharodontosaurus*: in the latter, the ratio of centrum length to anterior centrum width is 1.13, whereas it is approximately 2 in BSPG 2011 I 117.

Furthermore, as pointed out by Novas et al. (2005), Novas et al. (2013) and Canale, Novas & Haluza (2008), known cervical vertebrae of South American carcharodontosaurids differ considerably from vertebrae of *Sigilmassasaurus*. A well-preserved cervicodorsal vertebra of *Mapusaurus* (MCF-PVPH-108.82; probably one of the first three dorsal vertebrae, based on the position of the parapophyses; Coria & Currie, 2006) is markedly different from *Sigilmassasaurus* vertebrae thought to occupy similar axial positions. Among the differences are a rounded outline of the anterior condyle of the centrum, the lack of a ventrally expanded hypapophysis, presence of two separated pneumatic formanina on the lateral side of the centrum, well-developed laminae on the lateral side of the neural arch, relatively short transverse processes, presence of interzygapophyseal laminae, presence of a hyposphene, and large, laterally extensive spinopostzygapophyseal laminae (*Coria & Currie, 2006*). Additionally, *Mapusaurus* has a high and anteroposteriorly very short neural spine, deep centroprezygapophyseal fossae (anterior infraprezygapophyseal fossae of *Coria & Currie, 2006*) on the anterior side of the prezygapophyseal pedicles, and a relatively small, rounded neural canal. Similarly, *Sigilmassasaurus* can be easily distinguished from *Tyrannotitan*, which preserved on postaxial cervical, interpreted as a seventh cervical (MPEF-PV 1157; Novas et al., 2005; Canale et al., 2014). Since *Sigilmassasaurus* displays many differences to well-known carcharodontosaurids, the proposed overlap between "*Spinosaurus B*" and *Carcharodontosaurus* is not supported by the available evidence, and there is good evidence for spinosaurid affinities for the former taxon, a synonymy of *Sigilmassasaurus* with *Carcharodontosaurus* can be rejected. Furthermore, there is no conclusive evidence for carcharodontosaurid affinities from comparisons with other
<figure><img src="image_26.png" /><figcaption>**Figure 24** CMN 50792, posterior cervical vertebra of an indeterminate carcharodontosaurid. (A) right lateral view; (B) anterior view; (C) left lateral view. Abbreviations: cal, camellate pneumatic structure; cpf, central pneumatic foramen; cprf, centroprezygapophyseal fossa; pp, parapophysis; prz, prezygapophysis. Scale bar equals 10 cm.</figcaption></figure>

members of this clade. Within the Kem Kem compound assemblage, vertebrae of a more
'typical' carcharodontosaurid morphology have been found (e.g., CMN 50792, Fig. 24),
offering alternatives for cervical vertebral material of *Carcharodontosaurus*.

The best evidence is probably the close overlap and the synapomorphic features shared by “*Spinosaurus* B” and *Ichthyovenator*, the latter being a Spinosauridae.

**Systematic affinities of *Sigilmassasaurus***

Since its original description (Russell, 1996), *Sigilmassasaurus* has generally been regarded as a tetanuran theropod (e.g., Sereno et al., 1996; Sereno et al., 1998; McFeeters et al., 2013). Only Canale, Novas & Haluza (2008), in a published abstract, suggested that this taxon might actually be a large ornithopod, based on similarities of the vertebrae with those of *Iguanodon* Mantell, 1825, which also has very broad cervical centra, a well-developed ventral keel and poor lateral lamination. However, these characters have a wider distribution in dinosaurs and are also found in several theropod lineages. *Sigilmassasaurus* can be identified as a member of Tetanurae based on several synapomorphic features, including presacral vertebrae with a convex anterior condyle, a single pneumatic opening on the lateral side of the centrum, and widely spaced prezygapophyses (see also McFeeters et al., 2013).

Establishing the systematic position of this taxon within Tetanurae is more difficult,
given that only cervical and anterior dorsal vertebrae can be referred to *Sigilmassasaurus*.
Theropod material from the Kem Kem compound assemblage, including common oc-
curences of shed teeth, has been assigned to Carcharodontosauria (e.g., *Sereno et al.*, 1996;
*Cau, Dalla Vecchia & Fabbri*, 2013), Spinosauridae (e.g., *Dal Sasso et al.*, 2005; *Ibrahim et
al.*, 2014a), Ceratosauria (*Russell*, 1996; *Sereno et al.*, 1996; *Mahler*, 2005; *Carrano & Samp-
son*, 2008; *Porchetti et al.*, 2011; *Richter, Mudroch & Buckley*, 2013; *Evans et al.*, 2015), and
Dromeosauridae (*Amiot et al.*, 2004; *Richter, Mudroch & Buckley*, 2013). Ceratosaurian and
abelisaurid affinities of *Sigilmassasaurus* are unlikely given the tetanuran synapomorphies
present in the vertebrae of this taxon and numerous differences with the vertebrae of other
known ceratosaurs and abelisaurids (e.g., Gilmore, 1920; Madsen & Welles, 2000; O'Connor, 2007; Méndez, 2012). As noted above, carcharodontosaurid affinities, as suggested by Sereno et al. (1996), Sereno et al. (1998) and Brusatte & Sereno (2007) are also unlikely. *Sigilmassasaurus* material does not pertain to Dromeosauridae, as it lacks synapomorphies of Coelurosauria (such as amphiplatyan cervical vertebrae, Turner, Makovicky & Norell, 2012). As further outlined above, differences between the vertebrae of the holotype of *Spinosaurus aegyptiacus* and the vertebrae of *Sigilmassasaurus* preclude a referral of the latter to the former, but *Sigilmassasaurus* might represent a distinct taxon of spinosaurid.

Within spinosaurids, *Sigilmassasaurus* can best be compared with *Baryonyx* and *Ichthyovenator*, because large parts of the presacral vertebral column are known and detailed descriptions and images have been published for *Baryonyx* (*Charig & Milner, 1997*), and one of us (RA) has access to recently discovered cervical and dorsal material pertaining to the holotype specimen of *Ichthyovenator* (Allain, 2014). *Baryonyx* and *Suchomimus* have been recovered as sister taxa in latest phylogenetic analyses, and form the monophyletic Baryonynchinae within the Spinosauridae (e.g., *Carrano, Benson & Sampson, 2012*), in which the Asian *Ichthyovenator* was included (Allain et al., 2012). For *Suchomimus*, only a short initial report has been published (Sereno et al., 1998), and a detailed description of vertebral material is lacking. However, some comparative notes can be included here based on observations of the holotype material (by SWE & OWMR).

The other spinosaurid clade *Spinosaurinae* includes the genera *Spinosaurus*, *Irritator*, and *Angaturama*. *Kellner & Campos, 1996* (*Carrano, Benson & Sampson, 2012*), of which only *Spinosaurus* has vertebral material than could be compared to *Sigilmassasaurus* (see above).

The holotype material of *Baronyx* (NHMUK PV R 9951) includes remains of 17 presacral vertebrae. While only five cervical vertebrae were originally recognized within the holotype material, we argue that the vertebrae initially identified as D1 and D2 also represent cervical elements. Although *Charig & Milner* (1997: 30) argued that the typical number of cervical vertebrae in theropods was 9, we consider non-avian theropod dinosaurs to generally have ten cervical vertebrae. This is based on observations on well represented or articulated specimens, in which the first vertebra bearing a dorsal rib is the 11th presacral vertebra, such as *Eodromaeus Martínez et al., 2011* (*Martínez et al., 2011*), *Coelophysis* Cope, 1889 (BSPG cast of AMNH 7224), *Sciurumimus Rauhut et al., 2012*, BMMS BK 1, *Sinraptor* (*Currie & Zhao, 1993*), *Allosaurus* (SMA 0005; contra *Gilmore* (1920) and *Madsen* (1976)), and *Sinosauropteryx* Ji & Ji, 1996 (*Currie & Chen, 2001*). As noted above, the change from cervical to dorsal vertebrae is marked with a notable dorsal displacement of the parapophysis in theropods. In most theropods, the parapophysis still lies on the anteroventral end of the centrum in C10, but on or above the mid-height of the anterior rim of the centrum in D1, often straddeling the neurocentral suture. However, in some taxa, the displacement is less marked, and the anterior dorsals have the parapophysis on the ventral part of the anterior end of the centrum, but slightly above the ventral margin. Furthermore, the transverse process is usually strongly ventrolaterally directed
in mid-cervical vertebrae and becomes more lateral in posterior cervicals, until it achieves a more or less horizontal position in the first dorsal vertebrae.

In *Baryonyx*, *Charig & Milner* (1997) identified the axis and four further cervical vertebrae as C3, 5, 6 and 8. They also identified a continuous series of anterior dorsal vertebrae, ranging from D1 to D8. However, based on their overall morphology and in comparison with other theropods, we argue that the five cervicals identified by *Charig & Milner* (1997) probably represent C2 (axis) to C6, with the differences in the dimensions of the centra being largely due to deformation of the elements.

Based on this count, we think the originally assigned positions C2, C3, C5, C6, C8, D1, and D2 represent cervical vertebrae C2, C3, C4, C5, C6, C9, and C10, respectively. Consequentially, we disagree with some of the dorsal placements propsed by *Charig & Milner* (1997). However, as in *Charig & Milner* (1997), we recognize continuous morphological trends in the anterior dorsal vertebrae, so that we agree that they represent a successive series. Hence, the originally assigned positions D3 through D8 represent D1 through D6. Originally assigned D10 through D14 represent D9 through D13, as we agree that the posterior most preserved dorsal vertebra is the last presacral vertebra. Figure 25 shows a reconstruction of the neck and anterior parts of the dorsal vertebral series of *Sigilmassasaurus* and *Baryonyx*, and follows our new vertebral assignment for *Baryonyx*.

The new identifications are based on the following observations: the first vertebra with slightly elevated parapophyses is Charig & Milner's D3, here identified as D1; the first vertebra with horizontally oriented transverse processes in Charig & Milner's D3, here identified as D1; increased central length toward mid-cervical vertebrae and following length reduction together with increased centrum width, as well as transition from blade-like, transverse thin neural spine to vertically oriented, rod-like neural spine is in agreement with cervical morphology transitions in articulated or associated specimens of other theropod taxa, including *Allosaurus* (DINO 11541, SMA 0005), *Acrocanthosaurus* (OMNH 10146, formerly MUO 8-0-S9, Stovall & Langston, 1950), *Majungasaurus* (UA 8678, O'Connor, 2007), or *Sinraptor* (IVPP 10600, Currie & Zhao, 1993). The assignment of following dorsal vertebrae of *Baryonyx* is in agreement with observations on SMA 0005, which is an *Allosaurus* specimen preserving the entire presacral series. In *Baryonyx*, D4 ("D6") is the first vertebra with the parapophyses being located entirely on the neural arch, as in SMA 0005. Also as in *Baryonyx*, the degree of opisthocoely levels off in the anterior dorsal series of *Allosaurus*, with D1 being the first dorsal with a n oticeable decrease in the convexity of the anterior articular condyle. In SMA 0005, the third dorsal vertebra is the first one in which the anterior articular facet is truly flat. The appearance of a flat surface is delayed in *Baryonyx* to the D4 ("D6"). In general, the continuous dorsal assignment for the anterior and posterior dorsals proposed by *Charig & Milner* (1997) is followed here. In the following, referral to *Baryonyx* vertebrae will follow our new identification sheme.

When the cervical vertebrae of *Baryonyx* are aligned according to our new positional designations, the neck does assume a sigmoidal shape, *contra* the original description in which *Baryonyx* is described as having an uncurved neck (*Charig & Milner, 1986; Charig & Milner, 1997*). The curvature is less intense than in some theropods, such as *Sinrap-
<figure><img src="image_27.png" /><figcaption>**Figure 25** Neck reconstructions of *Sigilmassasaurus* and *Baryonyx*. (A) *Sigilmassasaurus*; (B) *Baryonyx*. Scale bar equals 10 cm. Scale bar only applies to *Baryonyx*, for which associated material is preserved. Reconstructions are based on the holotype material for *Baryonyx*, and material discussed in this paper for *Sigilmassasaurus*. Note that the first vertebra depicted is the C2 (axis), and that reconstruction includes anterior dorsal vertebrae.</figcaption></figure>

tor (Currie & Zhao, 1993), and instead of anterior and posterior intercentral articulations that are offset to one another, the curvature is achieved by the inclination of those facets. This condition is similar to *Sigilmassasaurus*, in which the mid-cervicals (e.g., CMN 50791, BSPG 2011 I 117) have anteroventrally inclined anterior facets like C6 of *Baryonyx*, and also *Ichthyovenator*, and posterior cervicals and anterior dorsals (e.g., BSPG 2006 I 54) have strictly anteriorly facing facets like in anterior dorsals of *Baryonyx* and *Ichthyovenator*. *Suchomimus* is slightly different in this respect, as the intercentral articulations show a clear offset to one another in both the posterior cervical and anterior dorsal vertebrae of the holotype (MNN GDF500).

The general proportions of the cervical centra of *Baryonyx*, *Ichthyovenator*, *Suchomimus* and *Sigilmassasaurus* are comparable. In all taxa, the centrum is elongate and slightly broader than high in mid-cervicals, and gets progressively shorter in posterior cervicals (see Fig. 26). The width–height ratios of *Baryonyx* do not quite approach those of *Sigilmassasaurus*, and there is no consistent width–height-ratio for *Baryonyx*, because
<figure><img src="image_28.png" /><figcaption>**Figure 26** Morphological changes along the cervical vertebral column of *Sigilmassasaurus* and *Baryonyx*. (A) CMN 50791, holotype mid-cervical vertebra (C6) of *Sigilmassasaurus brevicollis* in left lateral view; (B) BSPG 2005 I 56, posterior cervical vertebra (C8) of *Sigilmassasaurus brevicollis* in left lateral view; (C) NHMUK PV R 9951, C6 of *Baryonyx walkeri* in left lateral view; (D) NHMUK PV R 9951, C9 of *Baryonyx walkeri* in left lateral view. Note the extreme morphological changes in centrum length, orientation of prezygapophzses, and shape of the neural spine in both taxa. For discussion of axial placement of *Baryonyx* vertebrae see main text. Scale bars equal 10 cm.</figcaption></figure>

the articular facets become progressively wider posteriorly, but retain the same height (Charig & Milner, 1997). Similarly, *Suchomimus* has width–height ratios below those of *Sigilmassasaurus* (1.2 in the vertebra of MNN GDF500 that we consider to represent the D1), but is similar in respect to the reniform posterior facet. In *Ichthyovenator*, anterior dorsals like D1 have width–height ratios as in *Sigilmassasaurus*.

The mid-cervicals of *Baryonyx*, *Ichthyovenator* and *Sigilmassasaurus* are strikingly similar. The proposed similarities are exemplified by C6 of *Baryonyx* and *Ichthyovenator*,
and CMN 50791, the holotype of *Sp. maroccanus*. Besides the inclination of the condyles of their centra, C6 of *Baryonyx* and *Ichthyovenator*, and CMN 50791 share a distinct rim around the anterior articular facet, intercentral articulations which are transversely broader than high, gently reniform outline of the posterior articular facets, and elongate central pneumatic foramina posterodorsal to the parapophyses. Elongate central pneumatic foramina in mid-cervical vertebrae have been interpreted as an allosauroid character (Carrano, Benson & Sampson, 2012), although they are also present in some megalosauroid taxa, including *Baryonyx* (e.g., C4-6; Charig & Milner, 1997: Fig. 20, p. 33), spinosaurid vertebrae from the Kem Kem compound assemblage (BSPG 2006 I 57), and *Eustreptospondylus* (Sadleir, Barrett & Powell, 2008). Camerate pneumatic organization can be neither confirmed nor rejected for *Baryonyx* or *Ichthyovenator*, as the central pneumatic foramina are closed with matrix, and no CT-data is available for those taxa. However, a mid-cervical vertebra of an indeterminate spinosaurid that is not referable to *Sigilmassasaurus* (BSPG 2006 I 57, see above) has large single foramina on either side of the centrum. BSPG 2006 I 57 lacks some parts of its left anterolateral centrum. Because of this breakage, it is apparent, that this particular spinosaurid is another member of the group that bears large pneumatic cavities of the camerate type in cervical centra, although these camerae are more subdivided than the single large camera of *Sigilmassasaurus*. *Suchomimus* also displays the camerate type of pneumatization: the large foramen dorsal to each parapophysis leads into a single, undivided, large cavity in its cervical vertebrae (posterior cervical, MNN GDF500). Although there is no information about the internal tissue for all currently recognized spinosaurid taxa, the available evidence suggests that the entire Spinosauridae had camerate pneumatization.

Although *Baryonyx* cervical vertebrae have been described as lacking a ventral keel (Charig & Milner, 1997), the underside of C6 of *Baryonyx* does show a weak ridge. Importantly, the ridge merges posteriorly into a progressively broadening structure, which is slightly elevated and ends in the margin of the ventral part of the posterior cotyle of the centrum. This corresponds to the elevated triangular complex described herein for *Sigilmassasaurus*, although the structure is much less pronounced in *Baryonyx*. In *Ichthyovenator*, the ventral keel is absent, and although a stepped outline of the ventral central margin is seen in the C7 in lateral view, no solid ventral plateau as in *Sigilmassasaurus* is found (see above). This is similar in some vertebrae from the Kem Kem compound assemblage, which also have an albeit smaller stepped outline in lateral view, but lack a convex triangular plateau. Instead, the stepped outline is formed by two stout ventrolateral tubercula, which border a median ventral depression (see above, also see Fig. 20). The mid-cervicals of *Baryonyx* and *Sigilmassasaurus* furthermore share the blade-like, but relatively low neural spines, and the absence of laminae connecting the epipophyses with the prezygapophyses (Fig. 27), which are also absent in *Suchomimus*. The neural spines are higher in *Ichthyovenator*, but also blade-like in mid-cervicals (Fig. 27). Other differences between the taxa include the length of the epipophyses, which are larger in *Baryonyx* and *Ichthyovenator* than in *Sigilmassasaurus*, well-developed centroprezygapophyseal fossae in *Ichthyovenator* and *Baryonyx* (Fig. 27), a relatively
<figure><img src="image_29.png" /><figcaption>**Figure 27** Comparison between mid-cervical vertebrae of *Baryonyx* and *Sigilmassasaurus*. (A) Ce4 of *Baryonyx* in anterior view; (B) CMN 50791, *Sigilmassasaurus* mid-cervical vertebra (Ce6-7); (C) NHMUK PV 16427 *Sigilmassasaurus* mid-cervical (?Ce4) in anterior view; (D) Ce4 of *Baryonyx* in left lateral view; (E) NHMUK PV 17427 *Sigilmassasaurus* in left lateral view. Abbreviations: cprl, centroprezygapophyseal lamina; ifpl, infraprezygapophyseal lamina; prdl, prezygodiapophyseal lamina; sns, stepped neural spine. Scale bars equal 5 cm.</figcaption></figure>

prominent transverse ridge between the parapophyses in *Baryonyx*. However, all of these differences are related to diagnostic or at least characteristic features for *Sigilmassasaurus*, which for instance lacks centroprezygapophyseal fossae altogether and differs from most other theropods in having only weakly expressed epipophyses and a rudimentary and stout neural arch lamination. The weak development of epipophyses, although not evident in *Baryonyx* and *Ichthyovenator*, can also be found in *Suchomimus*.

Vertebrae of *Baryonyx* and *Ichthyovenator* with a more posterior axial position are also similar to *Sigilmassasaurus*. BSPG 2006 I 56, which is an important specimen in linking the vertebrae of the *Sp. maroccanus* morphology with the 'typical' *Sigilmassasaurus* morphology, shares aspects with posterior cervicals of *Ichthyovenator* and *Baryonyx*, like C9. These vertebrae share a rim around the anterior articular facet, prominent parapophyses in a low-central position and with deeply concave capitular facets (which is not so prominent in *Ichthyovenator*), gently reniform posterior articular facets, strongly curved postzygapophyses, stout transverse processes, and thick ridges running from the neural spine
onto the dorsal surface of the postzygapophyses in *Baryonyx* and *Sigilmassasaurus*, whereas *Ichthyovenator* retains epipophyses. Many of those features (e.g., rimmed articular facet; reniform shape of posterior facet; prominent, yet slightly higher positioned parapophyses) are also found in a posterior cervical of *Suchomimus* (MNN GDF500), but incomplete preservation of the specimen prevents comparison of many aspects of the neural arch. The probable D1 of the holotype does, however, show that transverse processes in the cervicodorsal region of *Suchomimus* were also robust, although the lamination is better developed than in *Sigilmassasaurus*. On the ventral side of the centrum, similarities to *Sigilmassasaurus* can be found in spite of the distortion of C9 of *Baryonyx*. Centrally behind the weak transverse ridge of the C9 starts a gently projecting keel. In the center of the underside of the centrum, the keel is abruptly sheared, and its posterior part is right-laterally displaced. From there on, the keel broadens to a posterior triangle, which merges with the posterior articular facet. Like in the mid-cervicals, this triangular structure is less plateau-like in *Baryonyx*. In *Suchomimus* (MNN GDF500), a ventral keel is well developed in a posterior cervical; it has a straight edge, broadens slightly anteriorly, but without developing into a hypapophysis, and it does not broaden posteriorly in any way. The neural spine of BSPG 2006 I 56 is partly broken, but appears to have been spike- or rod-like, and vertically oriented. The spine of the C9 of *Baryonyx* is vertically oriented and rod-like (see Fig. 26). Its anteroposterior length is enlarged by bony extensions with a rugose structure, which seem to be parts of ossified interspinal ligaments. In other, slightly more posterior positioned *Sigilmassasaurus* vertebrae, like CMN 41774 or CMN 41790, the neural spine is developed as a vertical, rod-like projection with a pointed end. The same can be seen in *Ichthyovenator* and *Suchomimus*. Although the described change in neural spine morphology can be observed in many theropods, and is likely to be functionally constrained as the anteroposterior length reduction of the spines allows for dorsoflexion at the beginning of the neck, the spines are more pointed in *Sigilmassasaurus*, *Ichthyovenator*, *Suchomimus* and *Baryonyx* than in other theropods, such as *Allosaurus* (DINO 11541, SMA 0005).

The centra of anterior dorsal vertebrae of *Baryonyx*, *Suchomimus* and *Ichthyovenator* share with *Sigilmassasaurus* strongly developed ventral keels. However, in *Baryonyx*, the ventral keel is straight along its course, while it is ventrally convex in NHMUK PV R 16345 and D1 of *Suchomimus* (MNN GDF500). In the latter taxon, keel morphology changes in following vertebrae, as the probable D2 has a straight keel, and D3/4 has three low and subparallel keels on the ventral side of the centrum. The hypapophyses of posterior cervicals and anterior dorsals show a distinct step anteriorly in *Sigilmassasaurus* and *Baryonyx*, whereas hypopophyses are absent in *Suchomimus*, despite a slight transverse thickening of the keel anteriorly. Rims around the anterior articular facet are strongly developed in *Sigilmassasaurus*, *Suchomimus* and *Baryonyx*, as well as in *Ichthyovenator*. The anteriormost dorsal vertebrae of *Baryonyx* (D1 and D2) show a reduced convexity of the anterior condyle, and in *Suchomimus*, the reduction of opisthocoely starts with the probably second dorsal vertebra. This is not the case in CMN 41858 and NHMUK PV R 16345, which are anterior dorsal vertebrae of *Sigilmassasaurus*, or in *Ichthyovenator*, which retains a hemispherical anterior condyle just like *Sigilmassasaurus*. The reduction seen in *Baryonyx*
is only apparent in tentative more posterior element of *Sigilmassasaurus*, like BSPG 2013 I 95 and CMN 41850. This suggests, that the opisthocoely of presacral vertebrae levels off later in the axial series in *Sigilmassasaurus* than in most theropods, including *Baryonyx*. However, the complete loss of opisthocoely seems to happen relatively far posterior in the vertebral column in all examined spinosaurids. The central pneumatic foramina show a plastic morphology in both *Sigilmassasaurus* and *Baryonyx*; the foramina are large on one side, and much smaller on the other in NHMUK PV R 16345 and D2 of *Baryonyx*.

One of the important similarities between *Sigilmassasaurus*, *Ichthyovenator*, *Suchomimus*, and *Baryonyx* is the development of their transverse processes. The transverse processes of dorsal vertebrae taper distally in most theropods, including *Majungasaurus* (O’Connor, 2007), *Allosaurus* (Madsen, 1976, SMA 0005), or *Neovenator* (Brusatte, Benson & Hutt, 2008), so that the transverse processes are anteroposteriorly more elongate at their medial bases than at the diapophyses. *Baryonyx*, *Suchomimus*, *Ichthyovenator* and *Sigilmassasaurus*, in contrast, have distal ends of their transverse processes that are as long anteroposteriorly as the medial base of the processes. Instead of tapering distally, the processes slightly reduce their anteroposterior dimension in the mid-length of the processes, and become broader again toward the diapophyses. This is exemplified by D1 of *Baryonyx* and NHMUK PV R 16345, and best seen in dorsal view. Both specimens have exceptionally stout and elongate transverse processes, but the lamination is more delicate in *Baryonyx*, *Suchomimus* and *Ichthyovenator*, in which anterior and posterior centrodiapophyseal laminae are well developed, as it is also the case in *Allosaurus* (DINO 11541, SMA 0005; Madsen, 1976). The length of the transverse processes, although extreme in the dorsal vertebrae NHMUK PV R 16345, is also conspicuous for posterior cervical and anterior dorsal vertebrae of *Sigilmassasaurus*, *Ichthyovenator*, *Suchomimus*, and *Baryonyx* (e.g., BSPG 2006 I 55; NHMUK PV R 16434; C9 and C10 of *Baryonyx*; D1 of *Ichthyovenator*; D1 of *Suchomimus*). In these vertebrae, the transverse processes are about as long as the width of their respective vertebral centra. In the well-known *Allosaurus*, posterior cervical vertebrae have transverse processes of shorter length (about 65% of the respective centrum width), and they are less thick and stout (e.g., *Allosaurus* vertebrae UMNH VP 8365, 10192; BYU 725/5266; 725/13051; 725/16628).

In anterior dorsal vertebrae, *Baryonyx* and *Suchomimus* retain the rod-like neural spine of posterior cervicals. In more posteriorly positioned dorsals (D10 of *Baryonyx*; unknown positioned vertebra of MNN GDF500; MNN GDF508 (referred to *Suchomimus*; *Sereno et al.*, 1998), the neural spine becomes blade-like, stretches over most of the anteroposterior length of the neural arch, is relatively tall and vertically oriented. In its central part, the neural spine is anteroposteriorly shorter than at its base and at its apex in D10 of *Baryonyx*, while the spine expands continuously in *Suchomimus* (MNN GDF500). Posterior to this position, like in D13 of *Baryonyx*, the spine becomes posteriorly inclined, and the anteroposterior constriction of the central part of the spine is lost. Although the neural spines of the posteriormost *Sigilmassasaurus* vertebrae known to date are only partly preserved, no posterior inclination is evident from the preserved base in CMN 41850, and a weak posterior tilt is evident in BSPG 2013 I 95. Also, the base of the spines of BSPG
2013 I 95 and CMN 41850 are broader than the dorsalmost parts preserved. Therefore, the transition of dorsal neural spine morphology observed in the isolated *Sigilmassasaurus* specimens seems to fit the patterns seen in *Baryonyx*.

In order to further test the phylogenetic affinities of *Sigilmassasaurus*, we performed a cladistics analysis based on a modified version of the Carrano, Benson & Sampson (2012) data matrix (see 'Materials & Methods,' as well as Data S1 for details) to evaluate the phylogenetic position of *Sigilmassasaurus*. Our analysis recovers 3.070 most parsimonious trees with a tree length of 1.041 steps from 10.000 replicates (for strict consensus tree, see Fig. S5), using TNT (Goloboff, Farris & Nixon, 2008). The topology of our phylogenetic analysis generally agrees with that of Carrano, Benson & Sampson (2012) with, for instance, a monophyletic Allosauria with the same ingroup relationships as in the tree presented by these authors, or a monophyletic Megalosauria with the same ingroup relationships except for Spinosauridae. In contrast to Carrano, Benson & Sampson (2012), we recover a large polytomy of spinosaurids, which include *Sigilmassasaurus*, *Spinosaurus aegyptiacus* (sensu Stromer, 1915), MSNM V4047, and *Ichthyovenator* in addition to those taxa found in the clade in the earlier analysis. However, the relationships within tetanurans more derived than *Chuandongocoelurus* He, 1984 and *Monolophosaurus* are not resolved in our strict consensus tree, so that we calculated a reduced consensus by pruning *Xuanhanosaurus* Dong, 1984 from the analysis, which was identified as a wildcard taxon. Figure 28 shows a reduced consensus tree of our analysis (see Fig. S6 for ingroup relationships of taxa capitalized in Fig. 28). Features of the topology and differences to the results of Carrano, Benson & Sampson (2012) are briefly discussed in Data S1, and additional trees such as the strict consensus and the ingroup relationships of larger groups generalized in Fig. 28 are also shown there. In both the strict and reduced consensus trees, *Sigilmassasaurus* and *Ichthyovenator* are found as members of a monophyletic Spinosauridae within Megalosauroidea. The Spinosauridae is supported by four unambiguous synapomorphies. Those are (i) the presence of crown striations (character 142:1; present in all spinosaurids preserving teeth, i.e., all but *Sigilmassasaurus*); (ii) anterior carina situated at the base of the crown on maxillary and dentary teeth (character 147:0; present in *Suchomimus*, *Baryonyx*, and *Ichthyovenator*. In Angaturama, Irritator Martill et al., 1996, *Spinosaurus*, and MSNM V4047, the character definition is not applicable to the morphology of the teeth, see discussion in Data S1); (iii) the presence of a ventral keel in posterior-most cervical and anterior dorsal vertebrae, which forms a straight to slightly convex ventral margin, and has an anterior end that protrudes ventrally from the anterior articular surface, so that it is separated from it by a distinct step (character 181:1; present in all spinosaurids preserving respective axial material); and (iv) the presence of pneumaticity/webbing at base of neural spines in middle to posterior dorsals (character 182:1; present in all spinosaurids preserving respective dorsal vertebrae). As only cervical and anterior dorsal vertebrae are known for *Sigilmassasaurus*, only one unambiguous spinosaur synapomorphy can currently be confirmed for this taxon. The ambiguous synapomorphies that support the Spinosauridae (those synapomorphies that have been recovered in some, but not all MPTs) are: fused premaxillary suture in adults (character 1:1); presence of a mediolateral
<figure><img src="image_30.png" /><figcaption>**Figure 28** Reduced consensus tree from our phylogenetic analysis after pruning *Xuanhanosaurus* using 3,070 most parsimonious trees. Capitalised terminal clades have been summarised, but are fully shown in a version of this tree in Fig. S6. Note that *Sigilmassasaurus* is found in a monophyletic *Spinosauridae*, highlighted by a turquoise box.</figcaption></figure>

constriction of the posterior portion of the premaxilla (character 8:1); subnarial formamen developed as an expanded channel (character 10:1); interlocking premaxillary–maxillary articulation (character 11:1); anteroposteriorly long anterior ramus of the maxilla (character 12:2); long an plate-shaped palatal process of the maxilla (character 15:1); absence of a maxillary fenestra (character 26:0); continuous dorsal and ventral portions of the antorbital fossa (character 44:1); lacrimal with angle <75° between anterior and ventral rami (character 49:1); subrectangular shape of the quadrate head in dorsal view (character 83:1); basipterygoid process of basisphenoid located anteroventrally of basal
tubera, with a basisphenoid recess opening posteroventrally (character 95:1); splenial
foramen developed as a large opening (character 129:1); paradental plates of mandible
obscured by medial wall of the dentary, only triangular apices may be visible from medial
view (character 139:1); reduced or absent curvature of teeth (character 141:1); circular
mid-crown cross-sections of teeth (character 144:1); tapered root-shape of teeth (character
145:1); absence of serrations in maxillary and dentary teeth (character 146:1); absence of
serration in premaxillary teeth (character 149:1); six or seven premaxillary teeth (character
150:3); Length-posterior height ratio of mid-cervical centra is 1.75–2.75 (character 179:1);
presence of accessory centrodiapophyseal lamina in middle to posterior dorsal vertebrae
(character 183:1); pronounced ventral keel in anterior dorsal vertebrae (character 185:1);
tall neural spines in dorsal vertebrae, extending twice the height of the centrum (character
194:2). All spinosaurid taxa are found in a polytomy in our analysis, so that the distinction
between Baryonychinae and Spinosaurinae is neither supported nor rejected by our
analysis. Excluding *Ichthyovenator* from the analysis, however, allows retrieval of the
dichotomy between Baryonychinae and Spinosaurinae, with *Sigilmassasaurus* being
recovered as a member of Baryonychinae. This group is supported by five unambiguous
synapomorphies (3:1; 5:0; 155:1; 177:0, 183:1), of which *Sigilmassasaurus* possesses only
one, i.e., neural spines in mid-cervicals anteroposteriorly longer than dorsoventrally high.
If *Sigilmassasaurus* is excluded from the analysis, *Suchomimus* and *Baryonyx* are recovered
among Baryonychinae, whereas *Ichthyovenator*, *Irritator*, *Angaturama* and *Spinosaurus*,
and MSNM V4047 form a polytomy with this clade. Given the morphological similarities
between cervical and dorsal material in *Ichthyovenator*, *Sigilmassasaurus* and *Baryonyx*
on one hand, but spinosaurine characters displayed by *Ichthyovenator* on the other hand,
this indicates that *Ichthyovenator* increases the character conflict within the group. At this
point, it is speculative to comment on the ingroup relationships of Spinosauridae, yet the
new morphological information gained from the examination of *Ichthyovenator* suggests
that the previously found distinction between Baryoninchinae and Spinosaurinae might
not be as strongly supported as previously thought. In any case, our phylogenetic analysis
strongly supports the hypothesis derived from the comparative anatomical analysis of our
study that *Sigilmassasaurus* is a valid taxon of the Spinosauridae.

Spinosaur diversity and ecology

Spinosauridae is a group of bizarre megalosauroid theropod dinosaurs, which have
received much interest due to their extremely large body size (Dal Sasso et al., 2005;
Therrien & Henderson, 2007), superficial similarities to crocodilians in terms of the
elongated rostrum, conical tooth shape, and suggested semiaquatic lifestyle (e.g., Taquet,
1984; Buffetaut, 1989; Charig & Milner, 1986; Charig & Milner, 1997; Sereno et al., 1998;
Taquet & Russell, 1998; Sues et al., 2002; Milner, 2003; Dal Sasso et al., 2005; Rayfield, 2007;
Allain et al., 2012; Ibrahim et al., 2014a), as well as their tendency to develop elongated
neural spines in at least part of their axial series (Stromer, 1915; Allain et al., 2012).

Currently, five spinosaurid taxa are considered valid, including *Baryonyx*,
*Ichthyovenator*, *Suchomimus*, *Irritator*, and *Spinosaurus* (Carrano, Benson & Sampson,
2012; Allain et al., 2012), although the validity of *Suchomimus* has been doubted by some authors (Sues et al., 2002). Other taxa have been proposed, including *Siamosaurus Buffetaut & Ingavat*, 1986, *Ostafrikasaurus Buffetaut* 2013, *Suchosaurus Owen*, 1842, *Cristatusaurus (Taquet & Russell, 1998)*, *Angaturama* and *Oxalaia Kellner et al.*, 2011, but are based on very fragmentary remains (*Owen*, 1840-; *Sauvage*, 1897-; *Buffetaut & Ingavat*, 1986; *Kellner & Campos*, 1996; *Taquet & Russell*, 1998; *Kellner et al.*, 2011; *Buffetaut*, 2012), the diagnostic validity of which is questionable (see e.g., *Sues et al.*, 2002; *Mateus et al.*, 2011; *Rauhut*, 2011). The most common spinosaurid occurences are by far isolated teeth (e.g., *Buffetaut*, 2008; *Canudo et al.*, 2008; *Hone, Xu & Wang*, 2010). Despite the fact that spinosaurid teeth are highly diagnostic (*Hendrickx & Mateus*, 2014), the identifications of many isolated teeth have been questioned due to the danger of confusion with crocodilian teeth (*Holtz*, 1998) or ceratosaurid theropods (*Fowler*, 2007). Of the five diagnostic spinosaurid taxa mentioned above, *Baryonyx* was recovered from the oldest strata, the Barremian Wessex Formation of England (*Charig & Milner*, 1997), and *Spinosaurus* from the youngest strata, the Cenomanian deposits of Egypt (*Stromer*, 1915). The temporal range, as well as the spatial range of spinosaurs is significantly increased when more ambiguous identifications are included. Oldest possible spinosaurid occurences include the isolated tooth described as *Ostafrikasaurus* from the Late Jurassic of Tendaguru (*Buffetaut*, 2008; *Buffetaut*, 2012 though see *Rauhut*, 2011) and isolated teeth showing spinosaurid characteristics from the late Middle Jurassic of Niger (*Serrano-Martínez et al.*, 2015), and youngest have been reported from the Santonian of China (*Hone, Xu & Wang*, 2010). Another possible spinosaur is *Chilantaisaurus* Hu, 1964, the systematic position of which has been a matter of debate (*Rauhut*, 2003; *Benson & Xu*, 2008; *Allain et al.*, 2012). Spinosaur remains have been confirmed from northern and western Africa, Europe, Asia, and South America (e.g., *Stromer*, 1915; *Taquet*, 1984; *Kellner & Campos*, 1996; *Martill et al.*, 1996; *Russell*, 1996; *Charig & Milner*, 1997; *Sereno et al.*, 1998; *Taquet & Russell*, 1998; *Dal Sasso et al.*, 2005; *Mateus et al.*, 2011; *Allain et al.*, 2012). Tentative spinosaur material is known from Australia (*Barrett et al.*, 2011; *Benson et al.*, 2012b, though see *Novas et al.*, 2013, for a different opinion). *Allain et al.* (2012) consider an isolated enlarged manual ungual phalanx of the first digit, originally referred to *Torvosaurus* (*Galton & Jensen*, 1979), as evidence for the presence of spinosaurs in North America, but this should be seen as tentative, pending more complete material from this continent.

Spinosaur diversity is highest during the late Early and the early Late Cretaceous, when several spinosaur taxa lived contemporaneously, although usually spatially separated from one another. However, if *Sigilmassasaurus brevicollis* is indeed different from *Spinosaurus*, at least two spinosaurid taxa are known from the Baharyia–Oasis (*Spinosaurus aegyptiacus* and *Sigilmassasaurus* sp.) and also from the Kem Kem compound assemblage. Recent studies suggest the presence of at least two spinosaurid taxa from these strata based on tooth morphology (*Richter, Mudroch & Buckley*, 2013) and the presence of two distinct spinosaurid quadrates (*Hendrickx*, 2006; C Hendrickx, pers. comm. to SWE, OWMR, and RA, 2013). Here, we have presented evidence from vertebral anatomy that also corroborates this hypothesis. Although the stratigraphic position of many fossils from
the Kem Kem compound assemblage is not precisely known and the temporal range covered by the respective deposits does not ultimatively necessitate co-occurrence of individual specimens (Cavin et al., 2010), the abundance and diversity of large bodied theropod dinosaurs from the Cenomanian of Northern Africa is conspicuous, yet not unique (compare with theropod faunas of the Campanian of eastern Asia, or the Late Jurassic Morrison fauna in northern America (Hone et al., 2011)). *Spinosaurus aegyptiacus*, *Sigilmassasaurus brevicollis*, *Bahariyasaurus ingens*, *Sauroniops pachytholus*, and *Carcharodontosaurus saharicus* all represent very large theropods, and remains of large abelisaurs and other theropods like *Deltadromeus agilis* (Sereno et al., 1996) suggest a high number of top predators. Direct competition could perhaps have been avoided by niche partitioning, for instance by different dietary and/or environmental preferences (see Fanti et al., 2014). Thus, the hypothesis of a predator-dominated ecosystem, derived from field occurrence data by Läng et al. (2013) is also supported by the taxonomic diversity of theropod dinosaurs from the ‘Kem Kem beds’ and the Baharyia Oasis.

Evidence for at least a partial picscivorous diet for spinosaurs comes from comparative tooth morphology (see review of Bertin, 2010), gut contents (Charig & Milner, 1997), isotope studies on spinosaur teeth (Amiot et al., 2010), and biomechanical analyses (Rayfield, 2007; Cuff & Rayfield, 2013). In *Sigilmassasaurus*, intense rugose bone surface structures can be found on the underside of the vertebrae, primarily on the anteroventral part of the centrum between the parapophyses and on the ventral side of the periphery of the posterior articular facet. These structures tend to be stronger in mid-cervicals, but also appear in more posterior positioned elements. The rugose pattern of ventral aspects of cervical centra can also be observed in other theropod dinosaurs, like *Allosaurus* (SMA 0005), but the intensity of the pattern is extreme in *Sigilmassasaurus*. Although such rugosities have not been observed in *Baryonyx*, they were present on the original *Spinosaurus aegyptiacus* material (Stromer, 1915).

Intense rugosities are usually osteological correlates for the origin or insertion of relatively strong musculature (Snively & Russell, 2007). Muscles on the ventral aspect of cervical centra in extant crocodylians and birds are associated with ventroflexion (Snively & Russell, 2007; Tsuihiji, 2007). Although this needs further testing from a biomechanical study, intense ventroflexor musculature might be advantageous for quickly snapping at fish and might thus be indicative of a piscivorous lifestyle of *Sigilmassasaurus*, as suggested for other spinosaurids.

## CONCLUSIONS

Vertebrae of *Spinosaurus maroccanus* and *Sigilmassasaurus brevicollis* represent elements from different axial positions of the same taxon, and the two taxa can therefore be synonymized under *Sigilmassasaurus brevicollis*. Although the mid-cervical and anterior dorsal vertebrae of this taxon seem to differ substantially in their morphology, observed changes along the axial series are shown to be similar to those of other tetanuran dinosaurs, including the spinosaurids *Baryonyx* and *Ichthyovenator*. Newly described vertebral material shows intermediate features between *Spinosaurus maroccanus* and
*Sigilmassasaurus* and thus further supports this hypothesis. *Sigilmassasaurus brevicollis* shows several autapomorphies and a suite of unusual features otherwise known only in *Ichthyovenator*. It is retained herein as a valid taxon, and a synonymy with *Spinosaurus aegyptiacus* is rejected. A phylogenetic analysis recovers *Sigilmassasaurus* as a spinosaur. This further increases the known diversity of spinosaurs, and suggests that the Kem Kem assemblage of Morocco yields at least two taxa of spinosaurs.

Institutional Abbreviations

**AMNH** American Museum of Natural History, New York, NY, USA

**BMMS** Bürgermeister Müller Museum Solnhofen, Solnhofen, Germany

**BSPG** Bayerische Staatssammlung für Paläontologie und Geologie, Munich, Germany

**BYU** Brigham Young University, Provo, UT, USA

**CMN** Canadian Museum of Nature, Ottawa, Canada

**DINO** Dinosaur National Monument, CO-UT, USA

**FASC** Faculté des Sciences Aïn Chock (University of Casablanca), Casablanca, Morocco

**IVPP** Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, China

**MCF** Museo Carmen Funes, Paleontología de Vertebrados, Plaza Huincul, Neuquén, Argentina

**MCNA** Museo de Ciencias Naturales y Antropológicas (JC Moyano) de Mendoza, Mendoza, Argentina

**MDS** Dinosaur Museum, Savannakhet, Laos

**MIWG** Museum of Isle of Wight Geology (now Dinosaur Isle, Isle of Wight Museum Service), UK

**MNN** Musée National du Niger, Niamey, Niger

**MOR** Museum of the Rockies, Bozeman, MT, USA

**MPEF-PV** Museo Paleontológico ‘Egidio Feruglio’, colección Paleontología Vertebrados, Trelew, Provincia de Chubut, Argentina

**NHMUK** Natural History Museum, London, UK

**MSNM** Museo di Storia Naturale di Milano, Milan, Italy

**P.P.** Museo di Storia delle Scienze Biomediche dell'Università degli Studi "G. d'Annunzio," Chieti, Italy

**PVL** Paleontología Vertebrados, Fundación Miguel Lillo, Tucumán, Argentina

**OMNH** Oklahoma Museum of Natural History (formerly MUO, Museum of the University of Oklahoma), Norman, OK, USA

**SGM** Ministerie de l'Energie et des Mines, Rabat, Morocco

**SMA** Sauriermuseum Aathal, Aathal, Switzerland

**ROM** Royal Ontario Museum, Toronto, Canada

**UA** Université d'Antananarivo, Antananarivo, Madagascar

**UMNH** Natural History Museum of Utah (formerly Utah Museum of Natural History), Salt Lake City, UT, USA

**USNM** United States National Museum, Smithsonian Institution, Washington, D.C., USA
## ACKNOWLEDGEMENTS

We are thankful to many people for discussions of this project, especially Richard Butler, Christian Foth, Adriana López-Arbarello, Mario Bronzati, Femke Holwerda, Randy Irmis, Roland Sookias, Markus Moser, David Legg, Christophe Hendrickx, and Nizar Ibrahim. Thanks to Rudyard Sadleir, Roger Benson, Patrick O'Connor, and Juan Canale for sharing photographs and giving helpful comments. Andrea Cau, Fernando Novas, Christophe Hendrickx, and an anonymous reviewer are thanked for critical comments on the manuscript. Sandra Chapman and Paul Barrett gave us access to *Sigilmassasaurus* and *Baryonyx* material at the NHM in London, and Paul Sereno generously allowed access to material of *Suchomimus* and a cast of FSAC-KK 11888 in Chicago, for which we are grateful. We also thank Martin Dobritz and Anne-Marie Kiunke-Seidenthal for taking the CT images.

## ADDITIONAL INFORMATION AND DECLARATIONS

### Funding

The authors have not received funding for this study.

### Competing Interests

The authors declare there are no competing interests.

### Author Contributions

* Serjoscha W. Evers and Oliver W.M. Rauhut conceived and designed the experiments, performed the experiments, analyzed the data, wrote the paper, prepared figures and/or tables, reviewed drafts of the paper.

* Angela C. Milner, Bradley McFeeters and Ronan Allain performed the experiments, analyzed the data, reviewed drafts of the paper.

### Data Availability

The following information was supplied regarding data availability:
The DICOM data of the scans is deposited at Figshare: BSPG 2006 I 54, 10.6084/m9.f figshare.1471654; BSPG 2011 I 115, 10.6084/m9.f figshare.1471659.

### Supplemental Information

Supplemental information for this article can be found online at http://dx.doi.org/10.7717/peerj.1323#supplemental-information.

## REFERENCES

* **Allain R. 2014.** New material of the theropod *Ichthyovenator* from Ban Kalum type locality (Laos): implications for the synonymy of *Spinosaurus* and *Sigilmassasaurus* and the phylogeny of Spinosauridae [Abstract 112]. *Journal of Vertebrate Paleontology, Program and Abstracts* 78.

* **Allain R, Xaisanavong T, Richir P, Khentavong B. 2012.** The first definitive Asian spinosaurid (Dinosauria: Theropoda) from the Early Cretaceous of Laos. *Naturwissenschaften* **99**:369–377 DOI 10.1007/s00114-012-0911-7.
**Amiot R, Buffetaut E, Lecuyer C, Wang X, Boudad L, Ding Z, Fourel F, Hutt S, Martineau F, Medeiros MA, Mo J, Simon L, Suteethorn V, Sweetman S, Tong H, Zhang F, Zhou Z. 2010.** Oxygen isotope evidence for semi-aquatic habits among spinosaurid theropods. *Geology* **38**:139–142 DOI 10.1130/G30402.1.

**Amiot R, Buffetaut E, Tong H, Boudad L, Kabiri L. 2004.** Isolated theropod teeth from the Cenomanian of Morocco and their palaeobiogeographical significance [Abstract]. *Revue de Paléobiologie, Genève* **9**:143–149.

**Barrett PM, Benson RBJ, Rich TH, Vickers-Rich P. 2011.** First spinosaurid dinosaur from Australia and the cosmopolitanism of Cretaceous dinosaur faunas. *Biology Letters* **7**:933–936 DOI 10.1098/rsbl.2011.0466.

**Belvedere M, Jalil N-E, Breda A, Gattolin G, Bourget H, Khaldoune F, Dyke GJ. 2013.** Vertebrate footprints from the Kem Kem beds (Morocco): a novel ichnological approach to faunal reconstruction. *Paleogeography, Paleoclimatology, Paleocology* **383–384**:52–58 DOI 10.1016/j.palaeo.2013.04.026.

**Benson RBJ, Butler RJ, Carrano MT, O’Connor PM. 2012a.** Air-filled postcranial bones in theropod dinosaurs: physiological implications and the ‘reptile’—bird transition. *Biological Reviews of the Cambridge Philosophical Society* **87**:168–193 DOI 10.1111/j.1469-185X.2011.00190.x.

**Benson RBJ, Rich TH, Vickers-Rich P, Hall M. 2012b.** Theropod fauna from southern Australia indicates high polar diversity and climate-driven dinosaur provinciality. *PLoS ONE* **7**:e37122 DOI 10.1371/journal.pone.0037122.

**Benson RBJ, Xu X. 2008.** The anatomy and systematic position of the theropod dinosaur *Chilantaisaurus tashuikouensis* Hu, 1964 from the Early Cretaceous of Alanshan, People’s Republic of China. *Geological Magazine* **145**:778–789 DOI 10.1017/S0016756808005475.

**Benyoucef M, Läng E, Cavin L, Mebarki K, Adaci M, Bensalah M. 2015.** Overabundance of piscivorous dinosaurs (Theropoda: Spinosauridae) in the mid-Cretaceous of North Africa: the Algerian dilemma. *Cretaceous Research* **55**:44–55 DOI 10.1016/j.cretres.2015.02.002.

**Bertin T. 2010.** A catalogue of material and review of the Spinosauridae. *PalArch’s Journal of Vertebrate Palaeontology* **7**:1–39.

**Bonaparte J. 1986.** Les dinosaures (Carnosaures, Allosauridés, Sauropodes, Cétiosaurides) du Jurassique moyen de Cerro Condor (Chubut, Argentine). *Annales de Paléontologie (Vertbrés-Invertbrés)* **72**:247–289.

**Britt BB. 1991.** Theropods of Dry Mesa Quarry (Morrison Formation, Late Jurassic), Colorado, with emphasis on the osteology of *Torvosaurus tanneri*. *BYU Geology Studies* **37**:1–72.

**Britt BB. 1993.** Pneumatic postcranial bones in dinosaurs and other archosaurs. PhD thesis, Canada: University of Calgary, Calgary. 383 pp.

**Brusatte SL, Benson RBJ, Hutt S. 2008.** The osteology of *Neovenator salerii* (Dinosauria: Theropoda) from the Wealden Group (Barremian) of the Isle of Wight. *Monograph of the Palaeontological Society* **162**:1–75 DOI 10.1080/02724630903416092.

**Brusatte SL, Sereno PC. 2007.** (Dinosauria: Theropoda) from the Cenomanian of Niger and a revision of the genus. *Journal of Vertebrate Paleontology* **27**:902–916 DOI 10.1671/0272-4634(2007)27[902:ANSOCD]2.0.CO;2.

**Buffetaut E. 1989.** New remains of the enigmatic dinosaur *Spinosaurus* from the Cretaceous of Morocco and the affinities between *Spinosaurus* and *Baryonyx*. *Neues Jahrbuch für Geologie und Paläontologie* **2**:79–87.

**Buffetaut E. 2008.** Spinosaurid teeth from the Late Jurassic of Tengaduru, Tanzania, with remarks on the evolutionary and biogeographical history of the Spinosauridae. In: Mazin J-M, Pouch
J, Hantzpergue P, Lacombe V, eds. *Mid-Mesozoic life and environments*. Lyon: Documents des Laboratoires de Géologie Lyon, 26-28.

**Buffetaut E. 2012.** An early spinosaurid dinosaur from the Late Jurassic of Tendaguru (Tanzania) and the evolution of the spinosaurid dentition. *Oryctos* 10:1-8.

**Buffetaut E, Ingavat R. 1986.** Unusual theropod dinosaur teeth from the Upper Jurassic of Phu Wiang, northeastern Thailand. *Revue de Paléobiologie* 5:217-220.

**Canale J, Novas F, Haluza H. 2008.** Comments about the cervical vertebrae referred to the African theropods *Carcharodontosaurus* and *Sigilmassasaurus*. In: *Libro de Resumenes III Congreso Latinoamericano de Paleontologia de Vertebrados*. Neuquén: III Congreso Latinoamericano de Paleontología de Vertebrados.

**Canale IC, Novas FE, Salgado L, Coria RA. 2014.** Cranial ontogenetic variation in *Mapusaurus roseae* (Dinosauria: Theropoda) and the probable role of heterochrony in carcharodontosaurid evolution. *Paläontolologische Zeitschrift* 1-11 Epub ahead of print Oct 11 2014
DOI 10.1007/s12542-014-0251-3.

**Canudo JI, Gasulla JM, Gómez-Fernández D, Ortega F, Sanz JL, Yagüe P. 2008.** Primera evidencia de dientes aislados atribuidos a Spinosauridae (Theropoda) en el Aptiano inferior (Cretácico Inferior de Europa: Formación Arcillas de Morella (España)). *Ameghiniana* 45:649-662.

**Carr TD, Williamson TE, Schwimmer DR. 2005.** A new genus and species of tyrannosauroid from the Late Cretaceous (Middle Campanian) Demopolis formation of Alabama. *Journal of Vertebrate Paleontology* 25(1):119-143 DOI 10.1671/0272-4634(2005)025[0119:ANGASO]2.0.CO;2.

**Carrano MT, Benson RBJ, Sampson SD. 2012.** The phylogeny of Tetanurae (Dinosauria: Theropoda). *Journal of Systematic Palaeontology* 10:211-300
DOI 10.1080/14772019.2011.630927.

**Carrano MT, Sampson SD. 2008.** The phylogeny of Ceratosauria (Dinosauria: Theropoda). *Journal of Systematic Palaeontology* 6:183-236 DOI 10.1017/S1477201907002246.

**Catuneanu O, Khalifa MA, Wanas HA. 2006.** Sequence stratigraphy of the Lower Cenomanian Bahariya Formation, Bahariya Oasis, Western Desert, Egypt. *Sedimentary Geology* 190:121-137
DOI 10.1016/j.sedgeo.2006.05.010.

**Cau A. 2014.** Spinosaurus revolution, Episodio II: Ode a "*Spinosaurus* C," e sulla gioia di completare il puzzle. Available at http://theropoda.blogspot.co.uk/2014/09/spinosaurus-revolution-episodio-ii-ode.html (assessed 10 October 2014).

**Cau A, Dalla Vecchia FM, Fabbri M. 2012.** Evidence of a New Carcharodontosaurid from the Upper Cretaceous of Morocco. *Acta Palaeontologica Polonica* 57:661-665
DOI 10.4202/app.2011.0043.

**Cau A, Dalla Vecchia FM, Fabbri M. 2013.** A thick-skulled theropod (Dinosauria, Saurischia) from the Upper Cretaceous of Morocco with implications for carcharodontosaurid cranial evolution. *Cretaceous Research* 40:251-260 DOI 10.1016/j.cretres.2012.09.002.

**Cavin L, Tong H, Boudad L, Meister C, Piuz A, Tabouelle J, Aarab M, Amiot R, Buffetaut E, Dyke G, Hua S, Le Loeuff J. 2010.** Vertebrate assemblages from the early Late Cretaceous of southeastern Morocco: an overview. *Journal of African Earth Sciences* 57:391-412
DOI 10.1016/j.jafrearsci.2009.12.007.

**Charig AJ, Milner AC. 1986.** *Baryonyx*, a remarkable new theropod dinosaur. *Nature* 324:359-361
DOI 10.1038/324359a0.

**Charig AJ, Milner AC. 1997.** *Baryonyx walkeri*, a fish-eating dinosaur from the Wealden of Surrey. *Bulletin of the Natural History Museum Geology* 53:11-70.
**Choubert G. 1948.** Essai sur la paléogéographie du Mésocrétacé marocain. *Volume Jubilaire de la Société des Sciences Naturelles du Maroc 1920210* **1945**:307–329.

**Coria RA, Currie PJ. 2006.** A new carcharodontosaurid (Dinosauria, Theropoda) from the Upper Cretaceous of Argentina. *Geodiversitas* **28**:71–118.

**Cuff AR, Rayfield EJ. 2013.** Feeding mechanics in spinosaurid theropods and extant crocodilians. *PLoS ONE* **8**:e65295 DOI 10.1371/journal.pone.0065295.

**Currie PJ, Chen P. 2001.** Anatomy of *Sinosauropteryx prima* from Liaoning, northeastern China. *Canadian Journal of Earth Sciences* **38**:1705–1727 DOI 10.1139/cjes-38-12-1705.

**Currie PJ, Zhao X. 1993.** A new carnosaur (Dinosauria, Theropoda) from the Jurassic of Xinjiang, People's Republic of China. *Canadian Journal of Earth Sciences* **30**:2037–2081 DOI 10.1139/e93-179.

**Dal Sasso C, Maganuco S, Buffetaut E, Mendez M. 2005.** New information on the skull of the enigmatic theropod *Spinosaurus*, with remarks on its size and affinities. *Journal of Vertebrate Paleontology* **25**:888–896 DOI 10.1671/0272-4634(2005)025[0888:NIOTSO]2.0.CO-2.

**De Broin F, Grenot C, Vernet R. 1971.** Sur la découverte d'un nouveau gisement de Vertébrés dans le Continental Intercalaire saharien: la Gara Samani (Algérie). *Comptes Rendus de l'Académie des Sciences de Paris* **272(D)**:1219–1221.

**Depéret C, Savornin J. 1927.** La faune de reptiles et de Poissons albiens de Timimoun (Sahara algérien). *Bulletin de la Société géologique de France* **27**:257–265.

**Dubar G. 1949.** *Carte géologique provisoire du Haut Atlas de Midelt, échelle au 1/200 000e.* Rabat: Notice Explicative, Notes et Mémoires du Service Géologique du Maroc 59bis, 60.

**Dyke GL. 2010.** Palaeoecology: different dinosaur ecologies in deep time? *Current Biology* **20**(22):R983–R985 DOI 10.1016/j.cub.2010.10.001.

**Ettachfini EM. 2008.** La transgression au passage Cénomanien–Turonien sur le domaine atlasique marocain. *Strata Série* 2:1–225.

**Ettachfini EM, Andreu B. 2004.** Le Cénomanien et le Turonien de la Plate-forme Pré africaine du Maroc. *Cretaceous Research* **25**:277–302 DOI 10.1016/j.cretres.2004.01.001.

**Evans DC, Barrett PM, Brink KS, Carrano MT. 2015.** Osteology and bone microstructure of new, small theropod dinosaur material from the early Late Creatceous of Morocco. *Gondwana Research* **27**:1034–1041 DOI 10.1016/j.gr.2014.03.016.

**Evers SW. 2012.** Description and interpretation of new vertebral material of the dinosaur *Sigilmassasaurus brevicollis* from the Cretaceous of Morocco and implications for the genus. B. Sc. thesis, Munich, Germany: Ludwig-Maximilians-Universität München. 80 pp.

**Evers SW, Rauhut OWM. 2012.** Evidence for spinosaurid affinities of *Sigilmassasaurus brevicollis* (Theropoda, Tetanurae) [Abstract S25]. *Terra Nostra* **2012**(3):50–51.

**Evers S, Rauhut OWM, Milner AC. 2012.** Was Stromer right? The affinities of *Sigilmassasaurus brevicollis* (Theropoda, Tetanurae) [Abstract 62]. *Journal of Vertebrate Paleontology, Program and Abstracts* 91.

**Fanti F, Cau A, Martinelli A, Contessi M. 2014.** Integrating palaeoecology and morphology in theropod diversity estimation: a case from the Aptian–Albian of Tunisia. *Palaeogeography, Palaeoclimatology, Palaeoecology* **410**:39–57 DOI 10.1016/j.palaeo.2014.05.033.

**Fitzinger L. 1843.** *Sytema reptilium. Fasciculus primus: Amblyglossae.* Vienna: Apud Braumüller and Seidel Bibliopolas.

**Fowler DW. 2007.** Recently rediscovered baryonynchine teeth (Dinosauria: Theropoda): new morphological data, range extension & similarity to *Ceratosaurus* [Abstract 55]. *Journal of Vertebrate Paleontology, Program and Abstracts* **27**(3):76.
**Galton PM, Jensen JA. 1979.** A new large theropod dinosaur from the Upper Jurassic of Colorado.
*BYU Geology Studies* **26**:1–12.

**Gauthier JA. 1986.** Saurischian monophyly and the origin of birds. *Memoirs of the California Academy of Science* **8**:1–55.

**Gilmore GW. 1920.** Osteology of the carnivorous dinosauria in the United States National Museum, with special reference to the genera *Antrodemus* (*Allosaurus*) and *Ceratosaurus*. *Bulletin of the United States National Museum* **110**:1–159.

**Goloboff PA, Farris JS, Nixon KC. 2008.** TNT, a free program for phylogenetic analysis. *Cladistics* **24**:774–786 DOI 10.1111/j.1096-0031.2008.00217.x.

**Harris J. 1998.** A reanalysis of *Acrocanthosaurus atokensis*, its phylogenetic status, and paleobiogeographic implications, based on a new specimen from Texas. *New Mexico Museum of Natural History and Science Bulletin* **13**:1–75.

**Hendrickx C. 2006.** Analyse morphofonctionnelle des carrés de Spinosauridae. M. Sc. thesis, Liége, Belgium: Université de Liége. 194 pp.

**Hendrickx C, Buffetaut E. 2008.** Functional interpretation of spinosaurid quadrates (Dinosauria: Theropoda) from the Mid-Cretaceous of Morocco [Abstract]. In: *56th annual symposium of vertebrate palaeontology and comparative anatomy*. Dublin, 25–26.

**Hendrickx C, Mateus O. 2014.** Abelisauridae (Dinosauria: Theropoda) from the Late Jurassic of Portugal and dentition-based phylogeny as a contribution for the identification of isolated theropod teeth. *Zootaxa* **3759**:1–74 DOI 10.11646/zootaxa.3759.1.1.

**Holliday CM, Gardner NM. 2012.** A new eusuchian crocodyliform with novel cranial integument and its significance for the origin and evolution of Crocodylia. *PLoS ONE* **7**:e30471 DOI 10.1371/journal.pone.0030471.

**Holtz TRJ. 1998.** Spinosaurs as crocodile mimics. *Science* **282**:1276–1277 DOI 10.1126/science.282.5392.1276.

**Holtz TRJ, Molnar RE, Currie PJ. 2004.** Basal Tetanurae. In: Weishampel DB, Dodson P, Osmólska H, eds. *The Dinosauria*. Berkeley: University of California Press, 71–110.

**Hone DWE, Wang K, Sullivan C, Zhao X, Chen S, Li D, Ji S, Ji Q, Xu X. 2011.** A new, large tyrannosaurine theropod from the Upper Cretaceous of China. *Cretaceous Research* **32**:495–503 DOI 10.1016/j.cretres.2011.03.005.

**Hone DWE, Xu X, Wang D-Y. 2010.** A probable baryonychine (Theropoda: Spinosauroidea) tooth from the Upper Cretaceous of Henan Province, China. *Vertebrata Palasiatica* **48**:19–26.

**Ibrahim N, Sereno PC, Dal Sasso C, Maganuco S, Fabbri M, Martill DM, Zouhri S, Myhrvold N, Iurino DA. 2014a.** Semiaquatic adaptations in a giant predatory dinosaur. *Science* **345**:1613–1616 DOI 10.1126/science.1258750.

**Ibrahim N, Varrichio DJ, Sereno PC, Wilson JA, Dutheil DB, Martill DM, Baidder L, Zouhri S. 2014b.** Dinosaur Footprints and other Ichnofauna from the Cretaceous Kem Kem beds of Morocco. *PLoS ONE* **9**(3):e90751 DOI 10.1371/journal.pone.0090751.

**Janensch W. 1925.** Die Coelurosaurier und Theropoden der Tendaguru–Schichten Deutsch–Ostafrikas. *Palaeontographica, Supplement* **7**:1–99.

**Kellner AW, Azevedo SAK, Machado EB, Carvalho LB de, Henriques DDR. 2011.** A new dinosaur (Theropoda, Spinosauridae) from the Cretaceous (Cenomanian) Alcântara Formation, Cajual Island, Brazil. *Anais da Academia Brasileira de Ciências* **83**:99–108 DOI 10.1590/S0001-37652011000100006.
**Kellner AWA, Campos D de A. 1996.** First Early Cretaceous theropod dinosaur from Brazil with comments on Spinosauridae. *Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen* **199**:151–166.

**Lambe LM. 1917.** The Cretaceous theropodus dinosaur *Gorgosaurus*. *Memoirs of the Geological Survey of Canada* **100**:1–79.

**Läng E, Boudad L, Maio L, Samankassou E, Tabouelle J, Tong H, Cavin L. 2013.** Unbalanced food web in a Late Cretaceous dinosaur assemblage. *Palaeogeography, Palaeoclimatology, Palaeoecology* **381–382**:26–32 DOI 10.1016/j.palaeo.2013.04.011.

**Larsson HCE, Sues H-D. 2007.** Cranial osteology and phylogenetic relationships of *Hamadasuchus rebouli* (Crocodyliformes: Mesoeucrocodylia) from the Cretaceous of Morocco. *Zoological Journal of the Linnean Society* **149**:533–567 DOI 10.1111/j.1096-3642.2007.00271.x.

**Lavocat R. 1954.** Sur les dinosauriens du Continental Intercalaire des Kem-Kem de la Daoura. *Comptes Rendus de la Dix-Neuvième Session, Congres Géologique International, Alger* **21**:65–68.

**Le Loeuff J, Läng É, Cavin L, Buffetaut E. 2012.** Between Tendaguru and Bahariya: on the age of the Early Cretaceous dinosaur sites from the Continental Intercalaire and other African formations. *Journal of Stratigraphy* **36**:486–502.

**Madsen JHJ. 1976.** *Allosaurus fragilis*: a revised osteology. *Utah Geological and Mineralogical Survey Bulletin* **109**:3–163.

**Madsen JHJ, Welles SP. 2000.** *Ceratosaurus* (Dinosauria, Theropoda), a revised osteology. *Utah Geology Survey Miscellaneous Publication* **00-2**:1–80.

**Mahler L. 2005.** Record of Abelisauridae (Dinosauria: Theropoda) from the Cenomanian of Morocco. *Journal of Vertebrate Paleontology* **25**:236–239 DOI 10.1671/0272-4634(2005)025[0236:ROADTF]2.0.CO;2.

**Mannion PD, Barrett PM. 2013.** Additions to the sauropod dinosaur fauna of the Cenomanian (early Late Cretaceous) Kem Kem beds of Morocco: palaeobiogeographical implications of the mid-Cretaceous African sauropod fossil record. *Cretaceous Research* **45**:49–59 DOI 10.1016/j.cretres.2013.07.007.

**Marsh OC. 1881.** Classification of the dinosauria. *American Journal of Science Series* **3**:241–244.

**Martill DM, Cruickshank ARI, Frey E, Small PG, Clarke M. 1996.** A new crested maniraptoran dinosaur from the Santana Formation (Lower Cretaceous) of Brazil. *Journal of the Geological Society* **153**:5–8 DOI 10.1144/gsjgs.153.1.0005.

**Martínez RN, Sereno PC, Alcober OA, Colombi CE, Renne PR, Montañez IP, Currie BS. 2011.** A basal dinosaur from the dawn of the dinosaur era in southwestern Pangaea. *Science* **331**:206–210 DOI 10.1126/science.1198467.

**Mateus O, Araújo R, Natário C, Castanhinha R. 2011.** A new specimen of the theropod dinosaur *Baryonyx* from the early Cretaceous of Portugal and taxonomic validity of Suchosaurus. *Zootaxa* **2827**:54–68.

**McGowan AJ, Dyke GJ. 2009.** A surfeit of theropods in the Moroccan Late Cretaceous? Comparing diversity estimates from field data and fossil shops. *Geology* **37**(9):843–846 DOI 10.1130/G30188A.1.

**McFeeters B. 2011.** A reevaluation of *Sigilmassasaurus brevicollis* (Dinosauria) from the Cretaceous of Morocco. B. Sc. thesis, Ottawa, Ontario, Canada: Carleton University. 65 pp.

**McFeeters B, Ryan MJ, Hinic-Frlog S, Schröder-Adams C, Sues H. 2013.** A reevaluation of *Sigilmassasaurus brevicollis* (Dinosauria) from the Cretaceous of Morocco. *Canadian Journal of Earth Sciences* **50**:636–649 DOI 10.1139/cjes-2012-0129.
**Méndez A. 2012.** The cervical vertebrae of the Late Cretaceous abelisaurid dinosaur *Carnotaurus sastrei*. *Acta Palaeontologica Polonica* **59**:569–579 DOI 10.4202/app.2011.0129.

**Milner AC. 2003.** Fish-eating theropods: a short review of the systematics, biology and palaeobiology of spinosaurs. *Journadas Internacionales sobre paleontologic de Dinosaurios y su Entoro* **2**:129–138.

**Novas FE, Agnolín FL, Ezcurra MD, Porfiri J, Canale JI. 2013.** Evolution of the carnivorous dinosaurs during the Cretaceous: the evidence from Patagonia. *Cretaceous Research* **45**:174–215 DOI 10.1016/j.cretres.2013.04.001.

**Novas FE, Dalla Vecchia FM, Pais DF. 2005.** Theropod pedal unguals from the Late Cretaceous (Cenomanian) of Morocco, Africa. *Revista del Museo Argentino de Ciencias Naturales Nueva Serie* **7**(2):167–175.

**Novas FE, De Valais S, Vickers-Rich P, Rich T. 2005.** A large Cretaceous theropod from Patagonia, Argentina, and the evolution of carcharodontosaurids. *Naturwissenschaften* **92**:226–230 DOI 10.1007/s00114-005-0623-3.

**O'Connor PM. 2007.** The postcranial axial skeleton of *Majungasaurus crenatissimus* (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar. *Journal of Vertebrate Paleontology* **27**:127–163 DOI 10.1671/0272-4634(2007)27[127:TPASOM]2.0.CO;2.

**Owen R. 1840–45.** *Odontography, or a Treatise on the Comparative Anatomy of the Teeth*. LXXIV. London: Hippolyte Bailliere.

**Owen R. 1842.** Report on British fossil reptiles. Part II. *Report of the British Association for the Advancement of Science* **11**:60–204.

**Pieper S, Halle M, Kikinis R. 2004.** 3D SLICER. In: *Proc IEEE international symposium biomedical imaging*. IEEE international symposium on biomedical imaging ISBI 2004. Piscataway: IEEE, 632–635.

**Pieper S, Lorensen W, Schroeder W, Kikinis R. 2006.** The NA–MIC Kit: ITK, VTK, pipelines, grids and 3D slicer as an Open Platform for the Medical Image Computing Community. In: *Proc IEEE international symposium on biomedical imaging*. Proc IEEE intl symp on biomedical imaging ISBI 2006. Piscataway: IEEE, 698–701.

**Porchetti SD'O, Nicosia U, Biava A, Maganuco S. 2011.** New Abelisaurid material from the Upper Cretaceous (Cenomanian) of Morocco. *Rivista Italiana di Paleontologica e Stratigrafia* **117**(3):463–472.

**Rauhut OWM. 2003.** The interrelationships and evolution of basal theropod dinosaurs. *Special Papers in Palaeontology* **69**:1–216.

**Rauhut OWM. 2005.** Osteology and relationships of a new theropod dinosaur from the Middle Jurassic of Patagonia. *Palaeontology* **48**:87–110 DOI 10.1111/j.1475-4983.2004.00436.x.

**Rauhut OWM. 2007.** Halswirbel riesiger Raubsaurier aus der Kreide Afrikas. *Freunde der Bayerischen Staatssammlung für Paläontologie und Historische Geologie e.V.*, Jahresbericht und Mitteilungen **35**:42–45.

**Rauhut OWM. 2008.** Cretaceous theropod faunas of Africa. In: Calvo JO, Juarez Valieri R, Porfiri JD, dos Santos D, eds. *III Congreso Latinamericano de Paleontología de Vertebrados, Libro de Resúmenes*. Neuquén: Honorable Legislatura de la Provincia de Neuquén, 211.

**Rauhut OWM. 2011.** Theropod dinosaurs from the Late Jurassic of Tendaguru (Tanzania). *Special Papers in Palaeontology* **86**:195–239.

**Rauhut OWM, Foth C, Tischlinger H, Norell MA. 2012.** Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic
of Germany. *Proceedings of the National Academy of Sciences of the United States of America* **109**:11746–11751 DOI 10.1073/pnas.1203238109.

**Rayfield EJ. 2007.** Finite Element Analysis and understanding the biomechanics and evolution of living and fossil organisms. *Annual Review of Earth and Planetary Sciences* **35**:541–576 DOI 10.1146/annurev.earth.35.031306.140104.

**Richter U, Mudroch A, Buckley LG. 2013.** Isolated theropod teeth from the Kem Kem Beds (Early Cenomanian) near Taouz, Morocco. *Paläontologische Zeitschrift* **87**:291–309 DOI 10.1007/s12542-012-0153-1.

**Rosset A, Spadola L, Ratib O. 2004.** OsiriX: an open-source software for navigating in multidimensional DICOM images. *Journal of Digital Imaging* **17**:205–216 DOI 10.1007/s10278-004-1014-6.

**Russell DA. 1996.** Isolated Dinosaur bones from the Middle Cretaceous of the Tafilalt, Morocco. *Bulletin du Muséum National d'histoire Naturelle. Section C, Sciences de la terre, Paléontologie, Géologie, Minéralogie* **18**:349–402.

**Sadleir RW, Barrett PM, Powell HP. 2008.** The anatomy and systematics of *Eustreptospondylus oxoniensis*, a theropod dinosaur from the Middle Jurassic of Oxfordshire, England. *Monograph of the Palaeontological Society* **627**:1–82.

**Sauvage H-E. 1897/1898.** Vertébrés Fossiles du Portugal. In: *Contributions à L'Études Poissons et des Reptiles du Jurassique et Crétacique*. Lisbon: Direction des Travaux Géologiques du Portugal. 46 pp.

**Schachner ER, Farmer CG, McDonald AT, Dodson P. 2011.** Evolution of the dinosauriform respiratory apparatus: new evidence from the postcranial axial skeleton. *Anatomical Record* **294**:1532–1547 DOI 10.1002/ar.21439.

**Seeley HG. 1887.** On the classification of the fossil animals commonly called Dinosauria. *Proceedings of the Royal Society of London* **43**:165–171 DOI 10.1098/rspl.1887.0117.

**Sereno PC. 1991.** Basal archosaurs: phylogenetic relationships and functional implications. *Journal of Vertebrate Paleontology* **11**:1–53 DOI 10.1080/02724634.1991.10011426.

**Sereno PC, Beck AL, Dutheil DB, Gado B, Larsson HCE, Lyon GH, Marcot JD, Rauhut OWM, Sadleir RW, Sidor CA, Varricchio DD, Wilson GP, Wilson JA. 1998.** A long-snouted predatory dinosaur from Africa and the evolution of Spinosaurids. *Science* **282**:1298–1302 DOI 10.1126/science.282.5392.1298.

**Sereno PC, Dutheil DB, Iarochene M, Larsson HCE, Lyon GH, Magwene PM, Sidor CA, Varricchio DJ, Wilson JA. 1996.** Predatory dinosaurs from the Sahara and Late Cretaceous faunal differentiation. *Science* **272**:986–991 DOI 10.1126/science.272.5264.986.

**Sereno PC, Larsson HCE. 2009.** Cretaceous crocodyliforms from the Sahara. *ZooKeys* **28**:1–143 DOI 10.3897/zookeys.28.325.

**Sereno PC, Martinez RN, Wilson JA, Varricchio DJ, Alcober OA, Larsson HCE. 2008.** Evidence for avian intrathoracic air sacs in a new predatory dinosaur from Argentina. *PLoS ONE* **3**(9):e3303 DOI 10.1371/journal.pone.0003303.

**Sereno PC, Wilson JA, Larsson HCE, Dutheil DB, Sues H-D. 1994.** Early Cretaceous dinosaurs from the Sahara. *Science* **266**:267–271 DOI 10.1126/science.266.5183.267.

**Serrano-Martínez A, Ortega F, Sciscio L, Tent-Manclús JE, Fierro Bandera I, Knoll F. 2015.** New theropod remains from the Tiourarén Formation (?Middle Jurassic, Niger) and their bearing on the dental evolution in basal tetanurans. *Proceedings of the Geologists' Association* **126**:107–118 DOI 10.1016/j.pgeola.2014.10.005.
**Smith JB, Lamanna MC, Lacovara KJ, Dodson P, Smith JR, Poole KJ, Giegengack R, Attia Y.**
2001. A giant sauropod dinosaur from an Upper Cretaceous Mangrove deposit in Egypt. *Science* **292**:1704–1706 DOI 10.1126/science.1060561.

**Smith JB, Lamanna MC, Mayr H, Lacovara KJ. 2006.** New information regarding the holotype of *Spinosaurus aegyptiacus* Stromer, 1915. *Journal of Paleontology* **80**:400–406 DOI 10.1666/0022-3360(2006)080[0400:NIRTHO]2.0.CO;2.

**Smith ND, Makovicky PJ, Hammer WR, Currie PJ. 2007.** Osteology of *Cryolophosaurus ellioti* (Dinosauria: Theropoda) from the early Jurassic of Antarctica and implications for early theropod evolution. *Zoological Journal of the Linnean Society* **151**:377–421 DOI 10.1111/j.1096-3642.2007.00325.x.

**Snively E, Russell AP. 2007.** Functional variation of neck muscles and their relation to feeding style in Tyrannosauridae and other large theropod dinosaurs. *The Anatomical Record* **290**:934–957 DOI 10.1002/ar.20563.

**Stovall JW, Langston Jr W. 1950.** *Acrocanthosaurus atokensis*, a new genus and species of Lower Cretaceous Theropoda from Oklahoma. *American Midland Naturalist* **43**:696–728 DOI 10.2307/2421859.

**Stromer E. 1915.** Ergebnisse der Forschungsreisen Prof. Stromers in den Wüsten Ägyptens. II Wirbeltier-Reste der Baharije-Stufe (unterstes Cenoman). 3. Das Original des Theropoden *Spinosaurus aegyptiacus* nov. gen., nov. spec. *Abhandlungen der Königlich Bayerischen Akademie der Wissenschaften. Mathematisch-physikalische Klasse* **28**:1–32.

**Stromer E. 1931.** Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens. II. Wirbeltierreste der Baharije-Stufe (unterstes Cenoman). 10. Ein Skelett–Rest von *Carcharodontosaurus* nov. gen. *Abhandlungen der Bayerischen Akademie der Wissenschaften, Mathematisch-naturwissenschaftliche Abteilung, Neue Folge* **9**:1–23.

**Stromer E. 1932.** Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens. II. Wirbeltierreste der Baharije-Stufe (unterstes Cenoman). 11. Sauropoda. *Abhandlungen der Bayerischen Akademie der Wissenschaften, Mathematisch-naturwissenschaftliche Abteilung, Neue Folge* **10**:1–21.

**Stromer E. 1934.** Ergebnisse der Forschungsreisen Prof. E. Stromers in den Wüsten Ägyptens. II. Wirbeltierreste der Baharije-Stufe (unterstes Cenoman). 13. Dinosauria. *Abhandlungen der Bayerischen Akademie der Wissenschaften, Mathematisch-naturwissenschaftliche Abteilung, Neue Folge* **22**:1–79.

**Sues H–D, 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.

**Taquet P. 1984.** Une curieuse spécialisation du crâne de certains Dinosaures carnivores du Crétacé: le muséum long et étroit des Spinosauridés. *Comptes Rendus de l'Académie des Sciences, Série II* **299**:217–222.

**Taquet P, Russell DA. 1998.** New data on spinosaurid dinosaur from the Early Cretaceous of the Sahara. *Comptes Rendus de l'Académie des Sciences de Paris* **327**:347–353 DOI 10.1016/S1251-8050(98)80054-2.

**Therrien F, Henderson DM. 2007.** My theropod is bigger than yours ... or not: estimating body size from skull length in theropods. *Journal of Vertebrate Paleontology* **27**:108–115 DOI 10.1671/0272-4634(2007)27[108:MTIBTY]2.0.CO;2.

**Tsuihiji T. 2007.** Homologies of the longíssimus, iliocostalis, and hypaxial muscles in the anterior presacral region of extant Diapsida. *Journal of Morphology* **268**:986–1020 DOI 10.1002/jmor.10565.
**Turner AH, Makovicky PJ, Norell MA. 2012.** A review of dromeosaurid systematics and paravian phylogeny. *Bulletin of the American Museum of Natural History* **371**:1–206 DOI 10.1206/748.1.

**Welles SP. 1984.** *Dilophosaurus wetherilli* (Dinosauria, Theropoda). Osteology and comparisons. *Palaeontographica A* **185**:85–180.

**Wilson JA. 1999.** A nomenclature for vertebral laminae in sauropods and other saurischian dinosaurs. *Journal of Vertebrate Paleontology* **19**:639–653 DOI 10.1080/02724634.1999.10011178.

**Wilson JA, Allain R. 2015.** Osteology of *Rebbachisaurus garasbae* Lavocat, 1954, a diplodocoid (Dinosauris, Sauropoda) from the early Late Creataceous-aged Kem Kem beds of southeastern Morocco. *Journal of Vertebrate Paleontology* Epub ahead of print e1000701 DOI 10.1080/02724634.2014.1000701.

**Wilson JA, D'Emic MD, Ikejiri T, Moacdieh EM, Whitlock JA. 2011.** A nomenclature for vertebral fossae in sauropods and other saurischian dinosaurs. *PLoS ONE* **6**(1) DOI 10.1371/annotation/53a56437-a810-4373-baee-16685ec20b2f.

**Zhao X-J, Benson RBJ, Brusatte SL, Currie PJ. 2010.** The postcranial skeleton of *Monolophosaurus jiangi* (Dinosauria: Theropoda) from the Middle Jurassic of Xinjiang, China, and a review of Middle Jurassic Chinese theropods. *Geological Magazine* **147**:13–27 DOI 10.1017/S0016756809990240.

**Zhao X, Currie PJ. 1993.** A large crested theropod from the Jurassic of Xinjiang, People's Republic of China. *Canadian Journal of Earth Sciences* **30**:2027–2036 DOI 10.1139/e93-178.

**Zanno LE, Gillette DD, Albright LB, Titus AL. 2009.** A new North American therizinosaurid and the role of herbivory in 'predatory' dinosaur evolution. *Proceedings of the Royal Society B, Biological Sciences* **276**(1672):3505–3511 DOI 10.1098/rspb.2009.1029.