Indeterminate cranial fragment (A–B); right splenial in lateral (C), rostral (D) and ventral (E) views; right prearticular in lateral (F) and rostral views (G); sketch of the right prearticular of MOR 693 () with virtual cross-section (H) diagnostic for G, also confirmed by CT slicing of the left side element of MOR 693 (I); splenial and prearticular in medial view, positioned in a reconstructed right lower jawof(J). Maxillary or dentary tooth in labial (K) and apical (L) views; close-up of the distal carina and denticles in lingual (M) and distal (N) views. Left cervical rib (O) in craniolateral view; fragmentary right (P) and left (Q) dorsal ribs in craniolateral view. Abbreviations as in text, ribs labeled as in Fig. 2 maps and caption. Scale bars equal two cm in (A)–(I), five cm in (J), one cm in (K), five mm in (L), one mm in (M)–(N), five cm in (O)–(Q). Photos by G. Bindellini, C. Dal Sasso, and M. Zilioli; drawing by C. Dal Sasso.

From a cranial element possibly comes a fragmentary bone with a very peculiar texture and high degree of vascularization ( Figs. 5A and 5B ). This bone is broken at any end, showing a T-shaped cross-section that at first glance recalls a vertebral transverse process with a deep and robust centrodiapophyseal lamina. However, the top of the T is perfectly flat and the two other bone surfaces are textured with fine ridges and pits, suggesting tight soft tissue attachments. This texture clearly differs from the parallel striations (i.e., muscle and ligament scars) seen on the vertebral processes (C. Dal Sasso & S. Maganuco, 2017, personal observation on Allosaurus fragilis MSNM V435). The internal structure also differs in being highly spongy rather than fibrolamellar, indicating a delicate, not robust structure. In addition, the purported centrodiapophyseal lamina widens toward its broken edge, suggesting a V-shaped branching or prosecution toward a wider portion of bone. One can hypothesize that this fragment was part of a cranial fenestra, but to relocate its anatomical position remains impossible.

Yates (2005 : fig. 5C, D) illustrates and describes a fragment “from near the posterior end” of the right prearticular of Dracovenator regenti that further confirms our interpretation: “the lateral surface bears two tall sharp-edged ridges, which extend across the length of the fragment, although their height decreases toward the posterior end. At the anterior end these ridges are closely spaced creating a deep, V-shaped sulcus between them. Toward the posterior end they diverge creating a broad, triangular fossa,” just like the dorsolateral groove in the Saltriovenator fragment ( Fig. 5F ). Moreover, “a thin, ventrally directed crest arises from the ventromedial margin. This creates a ventrolaterally facing, elongate fossa for the reception of the angular”: this is the ventrolateral groove seen in Fig. 5G .

Prearticular. The third jaw fragment ( Figs. 5F – 5G ) is here interpreted as a piece of the right prearticular, thanks to its very peculiar cross-section. The medial side is slightly convex and the lateral side is slightly concave, with the same curvature; the narrow ventrolateral and dorsal margins house a shallow groove each, whereas dorsolaterally a deep narrow groove enters the bone until the middle, giving its dorsal section a Y-shaped aspect. Such complex profile was used as a fingerprint to relocate the anatomical position of this bone fragment on complete theropod skulls and lower jaws. The best match occurred with the lower jaw of Allosaurus MOR 693 (C. Dal Sasso, 2004, personal observation). Carefully examining its disarticulated bones, we found an almost identical arrangement of grooves and processes at mid-caudal length of the right prearticular ( Fig. 5H ). That diagnostic cross-section, inferred by manual drawing, was later confirmed by unpublished CT data of the same specimen (E. Rayfield, 2016, personal communication; Fig. 5I ). The prearticular of Ceratosaurus , “in so far as one may judge from the parts preserved it is very similar to that of Antrodemus ” ( Gilmore, 1920 ). In facts, the Saltrio fragment matches the prearticular of MOR 693 even in size (both are 35 mm tall), thus it is consistent with a lower jaw about 80 cm long ( Fig. 5J ), and a body length of a subadult Allosaurus fragilis (see below).

The second jaw fragment is much narrower dorsoventrally but preserves a sharp ?ventral margin with an angle of 90°, just like the previous fragment, which suggests it might be the rostral continuation of the same bone. In facts, the splenial of coelophysoid-grade theropods (including Dilophosaurus ) is more elongate and rostrally tapering than that of tetanurans like Allosaurus . Interestingly, the splenial of Ceratosaurus nasicornis (C. Dal Sasso, 2017, personal observation on AMNH FR 27631- cast of the right lower jaw of USNM 4735) at mid-length displays a labioventral margin which is sharp-squared, highly similar to the margin of our fragments.

Splenial. The largest bone piece ( Figs. 5C and 5E ) preserves two other small fragments in tight sutural contact, respectively, with its dorsal and ventral margin; both sutures run restrocaudally, paralleling the finely ridged texture. The main fragment has a possibly medial surface missing the cortex and exposing the internal bone structure, a ventral sharp margin, oriented at 90°, and a flat ?lateral side that houses a longitudinal groove near its dorsal end. We think that this laminar element may be part of the middle portion of a right splenial, just caudal to the Meckelian foramen (absent in our fragment), where the splenial is clasped dorsally and ventrally by the caudal ends of the bifurcating dentary.

Three fragments that can be referred to the lower jaw have been recovered closely associated from block B. Besides their thin bony wall and finely parallel ridged texture, oriented rostrocaudally, the three fragments share complex grooved surfaces, reminiscent of the vascular grooves that usually run along the medial and internal sides of the lower jaw bones.

Affinities with the Ceratosauridae cannot be excluded, as the eroded lingual side in our specimen does not allow to verify the presence of the “diagnostic longitudinal grooves” described by Madsen & Welles (2000) ; however, in Saltriovenator it is absent “a wide concave area centrally positioned on the labial side of the crown,” mentioned as typical of this clade by Hendrickx, Mateus & Araujo (2015b) . Similarity to allosaurid and metriacanthosaurid crowns is in the crown proportions, as well as denticle count (12 per mm—C. Dal Sasso, 2004, personal observation on Allosaurus MOR 693), but they differ in having apparent transverse undulations.

The moderately compressed D-shaped cross-section and the lingually-sided carinae suggest a mesiolateral position for this tooth. In other words, it might be one of the first maxillary teeth from the upper right arcade, or one of the transitional dentary teeth from the lower left arcade. Comparison with the dentition of Early-Middle Jurassic theropod taxa allows to exclude affinity of the Saltrio tooth to known coelophysoids, which so far possess much smaller crowns (CH <15 mm) with minute denticles on the distal carina (>30 denticles per five mm; Buckley, 2009 ; Hendrickx & Mateus, 2014 ). Dilophosaurus is definitely more similar in denticle density (13 per 5 mm—C. Dal Sasso, 2004, personal observation on UCMP 37303), which in its turn is reported to be similar in Sinosaurus and Cryolophosaurus ( Xing, 2012 ). On the other hand, the teeth of abelisaurids are usually low and weakly recurved, have a slightly concave, straight or convex distal profile, and irregular non-oriented enamel texture, and megalosaurid teeth are characterized by centrally-positioned carinae on both mesial and lateral crowns ( Hendrickx, Mateus & Araujo, 2015b ).

The denticles are completely lost along the mesial carina, which is deformed, crushed, and eroded; small denticles (12 per 5 mm, i.e., 2.5 per mm) are preserved in a short medio-apical tract (7.3 mm long) along the less damaged distal carina ( Figs. 5K , 5M and 5N ). Following the morphological terms standardized by Hendrickx, Mateus & Araújo (2015a) , the preserved denticles are chisel-shaped, apicobasally subrectangular, perpendicular to the carina, and symmetrically convex in the outline of the external margin; the interdenticular space is deep and narrow, the interdenticular slit—when not altered by erosion—seems shallow and triangular, without a lamina joining two neighboring denticles, and there are no interdenticular sulci (blood grooves).

As in most basal theropods, the enamel surface texture is smooth without any wrinkles, also adjacent to the carinae, even at higher magnification ( Figs. 5M – 5N ), and any ornamentation—such as flutes, longitudinal grooves or ridges, transverse, or marginal undulations—is absent.

The transverse cross-section of the crown is intermediate between lenticular and D-shaped types ( sensu Hendrickx, Mateus & Araújo, 2015a ), being moderately compressed but asymmetrical: both mesial and distal carinae face linguomesially and linguodistally, respectively, but the distal edge is sharper than the mesial one, and the labial side of the crown is more convex that the lingual one. Approaching the carinae, the crown edges remain convex either on the labial or on the lingual side, different from the condition seen in salinon-shaped and parlinon-shaped teeth ( sensu Hendrickx, Mateus & Araújo, 2015a ): the concave areas seen in Fig. 5L near the carinae are due to diagenetic crushing.

Following Hendrickx, Mateus & Araújo (2015a) , with a crown height ratio of 2.39 and a crown base ratio of 0.48 ( Table 1 ), the tooth referred to Saltriovenator can be considered moderately elongated (category range 1.5–2.5) and moderately narrow (category range 0.5–0.6). At closer examination, the apicobasal curvature of the distal margin of the crown in labial/lingual view can be defined as marked, because the apex of the tooth is placed distally to the distal margin of the crown base, the mesial margin is clearly convex and the distal margin is concave.

A single tooth (MSNM V3659) was found isolated within a small limestone block near block A. Considering the uniqueness of the find, we confidently refer this tooth to the same taxon represented by the assemblage of bones. The specimen, missing the root and the apex, is 43 mm long and 18 mm wide (thus the tooth crown height is 2.4 times the base length). The crown is typically ziphodont: elongate, pointed, distally recurved and laterally compressed, without basal constriction, and with denticulate carinae ( Figs. 5L – 5N ).

These fragments range from 28 to 18 mm in maximum diameter, and from 15 to 8 in minimum diameter, which is consistent with mid-distal shaft rib size in a theropod about 25% larger than the 6-m-long Allosaurus fragilis MSNM V435. The bulkiest rib fragment (30 mm in diameter) has a subtriangular cross-section, a concavo-convex caudal side, a cranial ridge and a robust tapering keel projected medially. By comparison with the cross-section of a Ceratosaurus rib figured by Madsen & Welles (2000 : plate 19) and by direct comparison with MSNM V435 we refer this fragment to the proximal portion of a left dorsal rib.

Ribs. Based on the literature ( Allain, 2005 ; Madsen, 1976 ; Madsen & Welles, 2000 ) and on mounted skeletons of Allosaurus fragilis (MSNM V435) and Tyrannosaurus rex (MSNM V3902), we tentatively refer four fragments to left dorsal ribs, and five fragments to right dorsal ribs ( Figs. 5O – 5Q ). Our interpretation is based on the curvature of the preserved fragments, taking the keeled margin and the (usually laterodorsal) most flattened face as reference sides to orient the rib pieces, and assuming that the thicker cross-sections are proximal and the thinner-flatter ones are distal.

Scapular girdle and forelimbs

This is the most represented portion of the appendicular skeleton of Saltriovenator zanellai, including the best preserved and most complete elements (right humerus, right manus). The bones of the scapular girdle and the two humeri come all from block A; the bones of the right manus and part of the left humerus have been extracted from block B.

Scapula. A total of 15 fragments of the left scapula have been recovered from block A (Fig. 2), and patiently reconnected into three main portions (Figs. 6A–6D). Although the broken edges of the three portions are not complementary, they can be referred to adjacent parts of the same bone thanks to similar size and craniocaudal diameter, flattened structure with continuous longitudinal ridged texture and continuous mediolateral curvature, lenticular cross-section with same cortical bone lamination and thickness, and macro-vacuolar aspect of the inner spongy bone. In addition, the presence of a longitudinal keel along a tapering thinner cranial edge, and of a thicker crest along a robust caudal edge, in all the three portions, allowed to orient them correctly (e.g., see the elongate drop-like cross-section in Madsen & Welles, 2000: p. 20). Reconstructed this way, the scapula of Saltriovenator results approximately two times longer than the humerus.

Figure 6: Pectoral girdle of Saltriovenator zanellai. Left scapula in lateral (A), caudal (B), medial (C), and cranial (D) views; right scapular glenoid and coracoid in medial (E), caudal (F), lateral (G), and cranial (H) views; right coracoid in ventral (I) and dorsal (J) views; furcula in cranial (K), caudal (L), right lateral (M), ventral (N, with selected craniocaudal cross-sections), and dorsal (O) views; caudolateral portion of the right sternal plate in dorsal (P), lateral (Q), and ventral (R) views. Each bone fragment is labeled on the side cropping out in Fig. 2 . Abbreviations as in text. The position of co4 and co6 is hypothetical. Scale bars equal 10 cm in (A)–(J), five cm in (K)–(R). Photos by G. Bindellini and C. Dal Sasso; drawings by M. Auditore.

The distalmost portion of the left scapular blade is distinguished by its thinner cross-section, dorsally tapering in cranial and caudal view (Figs. 6B and 6D), dorsally diverging margins (Figs. 6A and 6C), and equally diverging surface texture. Possibly, five other small fragments showing similar flattening and texture (Fig. 2, sc label) are part of the same bone, or of the counterlateral element.

The costal (medial) surface of the scapular blade of Saltriovenator is flat. Only vascular pits and tracks, running on the medial surface of the acromion, are present. Below the neck, the scapula becomes much thicker (50 mm) and stouter along the caudal margin, whereas in cranial direction it tapers into the acromion. Only part of it is preserved in our specimen, with an axe-shaped fragment, that is, concave medially and convex laterally. Due to breakage, it is impossible to know how much was the acromion prominent, and if the scapulocoracoid was notched between acromion and coracoid (e.g., as it is in Dilophosaurus, unlike Ceratosaurus). On the lateral side of the scapula, a wide fossa proximal to the acromion and opposite to its medial concavity marks a powerful muscle attachment site, likely for the M. supracoracoideus (Burch, 2017). The maximum mediolateral diameter of the scapula (70 mm) is reached in the fragment that bears the glenoid face. The latter is intact, with an elongate D-shaped profile and a perfect line of contact (scapulocoracoid suture) with the glenoid of the right coracoid (Figs. 6E–6H), which fossilized close to it and to the right humerus (Fig. 2C). Given this, we refer the preserved scapular glenoid to the right scapula, albeit the fragments of the left scapula are by far most abundant. The well-preserved scapulocoracoid suture allows to restore the glenoid cavity, which appears directed mainly caudoventrally, without lateral exposition, as in basal neotheropods (Rauhut & Pol, 2017). The resulting glenoid angle, seen in lateral view, is a broad arc that measures about 110° (Fig. 6G). The scapular glenoid is wider (mediolaterally) than long (dorsoventrally), measuring 68 × 58 mm; its participation to the glenoid cavity is approximately equal to that of the coracoid. In medial and lateral view, the scapular glenoid shows a distinct outer lip that points caudally.

In the type specimen of Dilophosaurus wetherilli (C. Dal Sasso, 2004, personal observation on UCMP 37302) the scapular glenoid is squared rather than D-shaped, the angle formed by the glenoid with the articular surface for the coracoid is identical (140°), the glenoid angle is more open (125°), and the supraglenoid lip in lateral view is slightly more pronounced, almost hook-like, as in Ceratosaurus (Madsen & Welles, 2000) and Majungaurus (Carrano, 2007). In a subadult specimen of Allosaurus fragilis (C. Dal Sasso, 2004, personal observation on MOR 693) the scapular glenoid is subrectangular and much smaller than in Saltriovenator (49 mm long × 38 mm wide), as it is the coracoid glenoid (39 mm long × 40 mm wide), and they form a glenoid angle of 105°. In A. fragilis the scapula is dramatically narrower and more slender than in Saltriovenator, bladelike, with a dramatic proportional reduction of the coracoid. On the other hand, the scapula of Dilophosaurus wetherilli (Welles, 1984: fig. 25) has a subrectangular distal expansion, and a shaft with concave cranial and caudal edges.

Using the best preserved holotypic right scapula of Dilophosaurus to track a scaled reference silhouette in a tentative recomposition of the scapula of Saltriovenator, the latter fits a narrower, feebly cranially curved profile, without remarkable distal expansion: three important differences that make the scapula of Saltriovenator definitely more similar to those of Ceratosaurus dentisulcatus (Madsen & Welles, 2000: p. 20) and, secondarily, Eoabelisaurus (Pol & Rauhut, 2012).

Coracoid. A large thick, concavo-convex bone fragment (Figs. 6E–6J) is identified as the caudodorsal portion of the right coracoid, thanks to the preservation of the supracoracoid nerve foramen, the bicipital (also named lateral or coracoid) tubercle, the infraglenoid buttress, and the characteristic fossa than runs between these two prominent processes. As in several theropods, the bicipital tubercle is developed as a boss-like prominence: in some tetanurans, including Allosaurus (Madsen, 1976), this tubercle is extended along the lateral surface of the bone, forming a distinct ridge, but in Saltriovenator it is more prominent and forms a very elongate triangle, which is remiscent of the condition seen in several basal neotheropods, such as Coelophysis rhodesiensis (Raath, 1977), Zupaysaurus (Ezcurra & Cuny, 2007), and Dilophosaurus (see below), and different from the low rigde seen in Ceratosaurus (Madsen & Welles, 2000). The infraglenoid buttress seems taller and more pointed than the bicipital tubercle, but the latter is eroded, and the similar basal transverse diameter suggests that they were subequal in size, like in Dilophosaurus wetherilli (C. Dal Sasso, 2004, personal observation on UCMP 37302). In addition, in Saltriovenator the fossa is asymmetrical in the same way, with the bicipital side, which is subvertical, and the infraglenoid side oblique. In Allosaurus the infraglenoid-bicipital complex is much less pronounced, either in juvenile or adult specimens (C. Dal Sasso, 2004, personal observation on a growth series on loan to MOR from UUVP).

The coracoid of Saltriovenator lacks a lipped margin of the glenoid: the infraglenoid buttress forms a lip but it is directed laterally, not invading the glenoid margin. The supracoracoid nerve foramen continues in a groove, which is directed craniodorsally (dorsally in Sinosaurus—Hu, 1993; Ceratosaurus dentisulcatus—Madsen & Welles, 2000; Majungasaurus—Carrano, 2007), and still wide open at the broken end of the fragment. On the other hand, in Dilophosaurus wetherilli the supracoracoid nerve foramen widens in cranial direction, and with a more open angle, and does not show any groove or fossa (C. Dal Sasso, 2004, personal observation on UCMP 37302).

On the caudodorsal side of the bone, the coracoid glenoid is preserved as a smooth concave area, about 65 mm long (dorsoventrally) and 62 mm wide (mediolaterally). Laterally the glenoid is bordered by a rim, which extends in cranial direction from the infraglenoid buttress, and medially it becomes unclear because the bone cortex is missing. In facts, the nutrient foramen of the glenoid is widened by this lack of bone. The scapular face is deep and robust, remarkably similar to the “extremely thick contact with the scapula” described in Sinosaurus (Hu, 1993), also present in D. wetherilli (C. Dal Sasso, 2004, personal observation on UCMP 37302) and Segisaurus halli (Carrano, Hutchinson & Sampson, 2005: fig. 5).

The main coracoid fragment of Saltriovenator represents about one-third of the whole bone and preserves a good portion of the caudoventral margin, as shown by the ridge that borders the medial concavity. A second ridge marks the dorsomedial edge of the scapulocoracoid suture.

Four smaller bone pieces are referred to the flattened, fan-like portion of the coracoid as they show similar texture (fine parallel ridges), cross-section (concavo-convex bone, with one rounded margin), thickness (10–15 mm), and structure (thin-walled and finely spongy bone). Two of these fragments (rco2 and rco3 in Figs. 5E–5G) are likely the ventral continuation of the largest portion the right coracoid, as they were found overlapped onto it (Fig. 2B) and almost match each other along their fracture lines; the other ones, being thinner, are tentatively positioned more cranially (and might also belong to the left coracoid).

Based on preserved parts, the reconstructed coracoid appears proportionally smaller than expected from the size of the scapula, if compared to Dilophosaurus; the disproportion is minor in Ceratosaurus and Eoabelisaurus, and is the opposite in Allosaurus, due to its quite elongated scapula. Moreover, the coracoid of Saltriovenator is much longer parallel to the scapular suture than perpendicularly to it, and deep dorsoventrally (see depth of scapular facet in Table S1).

The caudoventral margin of the coracoid in Saltriovenator is gently rounded and lacks either a long pointed (e.g., Allosaurus) or distinctly hooked (e.g., Limusaurus) process, usually bound proximally by the infraglenoid buttress, which is present in Elaphrosaurus (Rauhut & Carrano, 2016), abelisaurids, and many averostrans, but not in Ceratosaurus (Rauhut, 2003). In facts, in Ceratosaurus the caudoventral margin is similarly curved, “short and bluntly rounded” (Tykoski & Rowe, 2004). In this aspect, the highest affinity is with the type specimens of Dilophosaurus wetherilli (C. Dal Sasso, 2004, personal observation on UCMP 37302) and Cryolophosaurus ellioti (Smith, Hammer & Makovicky, 2017; P. Makovicky, 2017, personal communication on FMNH PR 1821), both having the caudal margin of the coracoid regularly rounded with the same arch span. This suggests that also Saltriovenator had subelliptical rather than suboval coracoids, that is, it retained a rather plesiomorphic morphology, shared among basal saurischians.

Furcula. The furcula (Figs. 6K–6O) was extracted during acid treatment of block A, in close association to all other elements of the pectoral girdle (Fig. 2A). This bone cannot be misinterpreted as a gastral basket element because the two rami are stout, lack any longitudinal groove, and are medioventrally united in a clearly defined hypocleideum; furthermore, the complete right ramus terminates with a flat epicleideal facet (or epicleideum), which is typically spatulate and sulcated by ligamental scars, for articulation with the scapular acromion (Chure & Madsen, 1996; Carrano, Hutchinson & Sampson, 2005).

In the last two decades, furculae have been documented in nearly all but the most basal theropods (such as Herrerasaurus). The discovery of furculae in coelophysoids (Tykoski et al., 2002) has ruled out previous hypotheses on the phylogenetic position of Saltriovenator (Dal Sasso, 2001b), which were based on the idea that the fusion of the two clavicles occurred only in the Tetanurae. At present, the oldest known furculae belong to Coelophysis bauri and date back to the Late Triassic (Rinehart, Lucas & Hunt, 2007).

The furcula of Saltriovenator is V-shaped in ventral view (Fig. 6N) and U-shaped in cranial view (Fig. 6K) because, toward the symphysis, the dorsal margins of the two rami are concave, rather than straight. The preserved epicleideum is definitely twisted craniolaterally and expanded dorsoventrally at midlength of the facet, then it tapers to a pointed end. In cross-section (Fig. 6N), the two rami of the furcula are D-shaped in proximity to the symphysis, with the flat side facing dorsally; distally, the convex side develops a longitudinal ridge that eventually becomes the ventral edge of the epicleideum. The cross-section of the epicleideum is like a compressed D, with the flat side facing cranially. The hypocleideum of Saltriovenator projects caudoventrally seven to eight mm from the base of the clavicular rami, pointing to the left with a slight asymmetry. Interestingly, basal neotheropods such as Segisaurus and Dracoraptor lack (Carrano, Hutchinson & Sampson, 2005; Martill et al., 2016) or do not show (Chure & Madsen, 1996; Makovicky & Currie, 1998; Tykoski et al., 2002) prominent hypocleidea.

As commonly observed (Carrano, Hutchinson & Sampson, 2005), there is no trace of interclavicular suture between the two rami, which indicates a complete fusion. This was confirmed by CT analysis, which also excluded the presence of pneumatic openings and internal pneumatisation (Sereno et al., 2008), not to be confused with the wide medullary cavities visible especially inside the two rami.

With the method of measurement used by Nesbitt et al. (2009) we estimate an interclavicular angle of 140° for Saltriovenator zanellai. In coelophysoids, the furcula is variably U- or V-shaped and has an angle of 115–140°; the furcula is V-shaped also in allosauroids and ranges from 120° to 135° (Nesbitt et al., 2009). A “widely arched” furcula is present in Limusaurus (Xu et al., 2009).

Sternum. Remains of sternal plates were present in block A, partially mixed with other flat bone fragments of scapula and coracoid (Fig. 2B). In particular, we reconnected two fragments into a platelike, weakly curved bone margin (Figs. 5P–5R), which at first sight we hypothesized to be the distal end of the scapular blade, but eventually could not fit that position. This element shows a carinate (keeled) margin which is thinner than the thinnest preserved margin of the scapular blade, a similar spongy interior, but a different surface texture, which in facts is randomly oriented and finely pitted, well-vascularized, and it lacks the fine parallel striae that run all along the scapula. A couple of smaller fragments were recovered piled up on the former (Fig. 2A, st label) and share very similar shape and ornamentation. These features are also visible in the sternal plates MPG-KPC1 and 2, described by Sánchez-Hernández & Benton (2014: fig. 10) in Camarillasaurus cirugedae, a Cretaceous ceratosaurian from Spain. By comparison with the latter specimens, which are by far more complete, we suggest that our fragment may represent the caudolateral corner of the right sternal plate, and approximately one-eighth of the whole bone (Fig. 10B).

This would be the fourth time that sternal plates have been described in a ceratosaurian theropod, after Carnotaurus (Bonaparte, Novas & Coria, 1990), Limusaurus (Xu et al., 2009), and Camarillasaurus (Sánchez-Hernández & Benton, 2014).

Humerus. The humeri are the largest bones and the only paired elements known from both sides of Saltriovenator zanellai (excluding the clavicles that are fused into a furcula). The right humerus (Figs. 7A–7F) is by far more complete as it lacks only part of its head, and the adductor crest (=internal tuberosity of Madsen, 1976); the left humerus (Figs. 7G–7L) lacks not only the adductor crest, the extensor crest and part of the proximal diaphysis, but also the whole distal half. In both humeri, mainly on the fossae for the M. coracobrachialis, apparent subcircular marks are present; as written above (taphonomical section), these marks represent post-mortem damage (macroborings produced by marine invertebrates). The midshaft cut of the left humerus shows a wide open internal hollow, which occupies more than half of the diameter of the bone; CT analyses of the right humerus and right metatarsal II show that this relationship between cortex and medulla is present in the whole bone, even more marked towards and inside the epiphyses, as expected in the long bones of a theropod dinosaur.

Figure 7: Humeri of Saltriovenator zanellai. Right humerus in (A) lateral, (B) cranial, (C) medial, (D) caudal, (E) proximal, and (F) distal views; left humerus in (G) proximal, (H) distal, (I) lateral, (J) cranial, (K) medial, and (L) caudal views. Abbreviations as in text. Scale bar equals 10 cm. Photos by G. Bindellini.

The shaft torsion of the humerus of Saltriovenator, measured as the angle between the trasverse axes of proximal and distal ends when viewed proximally/distally, is about 74°. The main axis of the head is oriented transversally and collinear with the plane of the proximal expansion of the humerus, thus differing from some tetanurans (Benson & Xu, 2008) in which it forms a distinct acute angle with the main transversal plane of the proximal end. In proximal view, the head of the left humerus is more complete than the right one and appears ellipsoidal, expanded more lateromedially than proximodistally, that is, not inflated or dome-shaped, far from the globular shape seen in noasaurids and abelisaurids: thus remarkably plesiomorphic, as in Eoabelisaurus (Pol & Rauhut, 2012), and contrary to Limusaurus (Xu et al., 2009). The lateral tuberosity of the humerus is placed laterodistally to the head, at the level of the proximal end of the deltopectoral crest. It is well-developed, giving the lateral margin a straight profile in cranial and caudal view; in late-diverging ceratosaurians it is reduced, giving the humerus a broadly convex margin. The right humerus of Saltriovenator appears almost straight also in lateral and medial view, being just slightly bent in its distal third. Likely, the missing adductor crest was as slightly curved as the distal epiphysis, giving the whole bone a only moderately sigmoid shape, as in most Neoceratosauria (Tykoski & Rowe, 2004), and in some large-sized basal tetanuran taxa, such as Poekilopleuron (Allain & Chure, 2002; C. Dal Sasso & S. Maganuco, 2004, personal observation on plastotype MNHN 1897-2), Acrocanthosaurus, Szechuanosaurus (Gao, 1993), and Xuanhanosaurus (Novas, Aranciaga Rolando & Agnolín, 2016). It is also similar to Dilophosaurus (Welles, 1984), although in the latter the diaphysis is more slender and a little more bowed, with an arch which is continuous from the dorsal lamina to the entepicondylar crest (C. Dal Sasso, 2004, personal observation on UCMP 37302). In coelophysoids, the humerus shows a clearly sigmoid curvature, as well as torsion (Tykoski & Rowe, 2004). In Allosaurus (Madsen, 1976; C. Dal Sasso, 2004, personal observation on MOR 693) the humerus is markedly sigmoid, the diaphysis in craniocaudal view is narrow and bowed medially, and there is an increased torsion of the epiphyses, which are proportionally more enlarged.

The deltopectoral crest is the largest process of the humerus of Saltriovenator: proximally, it is not confluent with the humeral head, being separated from it by a shallow concavity that houses a thin extensor crest, like in Allosaurus (Madsen, 1976) and unlike Dilophosaurus (Welles, 1984). Distally, the deltopectoral crest becomes transversely inflated, and—remarkably and uniquely—it protrudes craniomedially for more than twice the midshaft diameter size, finally meeting the distal lamina abruptly, with an angle of 90°. The deltopectoral crest of Saltriovenator forms an angle of 50° with the plane of the distal condyles and it extends for more than 2/5 the humeral length, as in Dilophosaurus wetherilli (C. Dal Sasso, 2004, personal observation on UCMP 37303) and contrary to most tetanuran theropods, in which it extends in cranial direction. On the left humerus, the protruding end of the deltopectoral crest is much more pointed than in the right humerus, nearly hooked, being grown over the distal lamina—in this feature, it recalls Acrocanthosaurus (Currie & Carpenter, 2000). This condition, as well as the right-angled distal end, differs from the more gentle transition between the crest and the shaft seen in most theropods, including Ceratosaurus (Madsen & Welles, 2000) and Dilophosaurus (C. Dal Sasso, 2004, personal observation on UCMP 37303), and other taxa that possess a similarly protruding deltopectoral crest, such as Poekilopleuron (Allain & Chure, 2002), Szechuanosaurus (Gao, 1993), Torvosaurus (Galton & Jensen, 1979), and Australovenator (Novas, Aranciaga Rolando & Agnolín, 2016). A nearly perpendicular distal lamina of the deltopectoral crest can be seen only in Segisaurus (Carrano, Hutchinson & Sampson, 2005).

The proximodistal length of the remaining humeral shaft, between the deltopectoral crest and the distal condyles, is about five times the minimal shaft diameter. In this portion, the shaft does not bear any distinct tuber along the craniolateral surface, whereas on the caudolateral margin, at level of the distal lamina, an elongate scar for the M. latissimus dorsi is present, like in Majungasaurus (Carrano, 2007: fig. 3).

In cranial view, the humerus of Saltriovenator appears non-sigmoid, almost straight, similar to the holotype of Ceratosaurus dentisulcatus (Madsen & Welles, 2000: fig. B, D) but a little less bulky, with less pronounced, gently enlarged epiphyses; therefore it markedly differs from the midshaft-constricted holotype of C. magnicornis (Madsen & Welles, 2000: fig. A, C). In facts, in Saltriovenator the distally placed distal condyles are slightly less than twice larger than the diaphysis at its minimum transverse diameter.

In distal view, the partially eroded (or not completely ossified) condyles are only weakly convex (nor hemispherical, neither totally flattened) and subequal in size, the ectocondyle being slightly shorter in mediolateral direction, but deeper craniocaudally. The same condition is observed in Dilophosaurus wetherilli (C. Dal Sasso, 2004, personal observation on UCMP 37303) and Cryolophosaurus ellioti (Smith et al., 2007: fig. 14 C-D). The intercondylar sulcus is preserved only at its ends, it is shallower than in Dilophosaurus, mediolaterally narrow and slit-like in shape. The distal fossa is moderately developed. Although not hypertrophied, the ectepicondylar crest seems more developed than in Dilophosaurus and than the entepicondylar crest, but this may be an artifact of preservation, because the medial wall of the entocondyle is missing. In Allosaurus (Madsen, 1976; C. Dal Sasso, 2004, personal observation on MOR 693) the disproportions between the ecto- and the entocondyle increase, the latter becoming almost twice than the former in mediolateral length and much more compressed craniocaudally; the intercondylar groove markedly divides the two condyles and the ectepicondylar crest appears as robust as in Saltriovenator.