Piatnitzkysaurus floresi Bonaparte 1979
Creators: name: Pradelli Diego Pol, Luciano A.
name: Ezcurra, Martín D.
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Dinosauria
Piatnitzkysauridae
Piatnitzkysaurus
Piatnitzkysaurus floresi

description: Piatnitzkysaurus floresi Bonaparte, 1979
Holotype: PVL 4073: incomplete left maxilla, left frontal, anterior end of a left dentary with erupting teeth, partial braincase, 14 presacral vertebrae including axis, cervical, and dorsal vertebrae, incomplete sacrum with four vertebrae, two anterior caudal vertebrae, fragments of ribs, almost complete left and right scapulae, right and part of the left coracoids, right humerus, left ulna, fragment of postacetabular process of the right ilium, and left and right pubes, shaft and distal end of ischia, femora, tibiae, and fibulae, and some indeterminate fragments. In this review, new material has been identified that corresponds to part of the left coracoid.
Referred specimen: MACN-Pv-CH 895: incomplete right maxilla with erupting teeth, one dorsal and two caudal vertebral centra, two posterior dorsal vertebrae, complete sacrum with five vertebrae (four of them are fused), fragments of ribs, right humerus, left ilium, ischial peduncle of another left ilium, proximal end of left and right pubes, proximal and distal end of right ischium, iliac peduncle and distal end of left ischium, left femur, left tibia, left metatarsals II, III, and IV, left distal tarsals 3 and 4, and one partial phalanx. In this review, new material has been identified that corresponds to the ischial peduncle of a left ilium, iliac peduncle of left ischium, and a partial phalanx. There is no positive evidence to associate the isolated teeth to Piatnitzkysaurus floresi owing to the difference in size between these and the preserved maxillae (left one from the holotype and right one from the referred specimen) and dentary (from the holotype).
Occurrence: 1 km west of Farias house at Cerro Cóndor village, Chubut Province, Argentina.Upper levels of the Cañadón Asfalto Formation dated between 178.766 ± 0.092 and 178.070 ± 0.21 Mya, Toarcian, Early Jurassic (Pol et al. 2020).
Diagnosis: Piatnitzkysaurus floresi was originally diagnosed by Bonaparte (1986) as an ‘Allosaurid with deep depressions between the basioccipital condyle and the opisthotic process; braincase similar to that of Eustreptospondylus but with more pronounced lateral basisphenoid depressions and alar process of the laterosphenoid. Most postcranial characters comparable to those of Allosaurus, but with a shorter scapula and a coracoid not expanded but subcircular. Pubis with an obturator foramen totally enclosed by a bony lamina and forming a modest neck; ischium less reduced ventrally than that of Allosaurus. Ulna, tibia and femur are more slender than in Allosaurus, but proportionally a little more massive than in Dilophosaurus.’. More recently, Rauhut (2003) amended the diagnosis of the species as follows: ‘Basis of the ascending process of the maxilla strongly inflated’. We plan to redescribe in detail the rest of the anatomy of Piatnitzkysaurus floresi in future contributions. Thus, an updated, complete emended diagnosis will be provided at the end of this series of contributions. Nonetheless, Piatnitzkysaurus differs from other non-coelurosaurian averostrans in the following unique combination of character states of the appendicular skeleton: marked glenoid lip of the coracoid; biceps tubercle of the coracoid developed as a posteroventrally oriented ridge; length of deltopectoral crest relative to total humerus length between 0.43 and 0.49; distal end of the humerus canted relative to the proximal end in anteroposterior view; well-defined fossa on the anterior surface of the ulnar condyle of the humerus; absence of a groove oriented oblique to long axis on the proximal surface of the femoral head; heart-shaped cross-section of paired midshafts of the ischia; pubic peduncle of the ischium extended anteriorly; posterior side of the distal tarsal 4 widens lateromedially.
Furthermore, the appendicular skeleton of Piatnitzkysaurus floresi differs from Condorraptor currumili in: the ischiatic peduncle of the ilium is shorter in Condorraptor; pubic tubercle more expanded laterally in anterior view in Condorraptor; obturator foramen ventrolaterally oriented in the pubis of Piatnitzkysaurus, whereas it is ventrally oriented in Condorraptor; mediodistal crest of the femur more medially expanded in Condorraptor; femoral shaft more recurved in lateral view in Condorraptor; the cnemial crest is subrectangular in shape in lateral view in Piatnitzkysaurus, whereas it is rounded in Condorraptor; proximal condyles of the tibia more rounded and separated by a posterior notch in Piatnitzkysaurus; lateral ridge of the tibial proximal end less laterally developed in Condorraptor; the articular surface of the distal end is less proximally expanded in the metatarsal IV of Piatnitzkysaurus.
Description
Pectoral girdle
Scapula: The holotype (PVL 4073) includes both almost complete scapulae (Fig. 1). The right element lacks part of the distal end, and most of the acromial region is missing in the left one. In contrast to ceratosaurian theropods (e.g. Carnotaurus sastrei Bonaparte, 1985: MACN-Pv-CH 894; Ceratosaurus nasicornis Marsh, 1884: Gilmore 1920, Eoabelisaurus mefi: MPEF-PV 3390; Majungasaurus crenatissimus Depéret, 1896: Carrano 2007), the scapula and coracoid are unfused, as in allosauroids (e.g. Allosaurus fragilis Marsh, 1877: Madsen 1976a, Sinraptor dongi Currie & Zhao, 1993: Currie and Zhao 1993). However, this condition varies in some groups (e.g. in Megalosauroidea: Megalosaurus bucklandii Mantell, 1827 has got them fused: Benson 2010; and Baryonyx walkeri Charig & Milner, 1986 unfused: Sereno et al. 1998) and also during ontogeny (Griffin 2018). The glenoid region is subspherical to reniform in proximal view and has a lateral slightly thickened edge. The surface that articulates with the coracoid is anteriorly flat and narrow and becomes concave and transversely broad posteriorly. The glenoid fossa is in the most posterior region and faces mainly ventrally (Fig. 1B, I), but with a minor lateral component, as in non-averostran theropods (e.g. Dilophosaurus wetherilli Welles, 1954: Marsh and Rowe 2020; Zupaysaurus rougieri Arcucci & Coria, 2003: PULR 076) and megalosauroids (although the lateral inclination is less pronounced; e.g. Megalosaurus bucklandii: Benson 2010). This condition differs from ceratosaurian theropods (e.g. Carnotaurus sastrei: MACN-Pv-CH 894; Ceratosaurus dentisulcatus: Madsen and Welles 2000; Eoabelisaurus mefi: MPEF-PV 3390; Majungasaurus crenatissimus: Carrano 2007) and Allosaurus fragilis (Madsen 1976a), in which the glenoid fossa faces more ventrally. This fossa is crescent shaped in ventral view and has a rough texture. The dorsal lip of the fossa is slightly thickened and is more robust than in abelisaurids (e.g. Carnotaurus sastrei: MACN-Pv-CH 894; Majungasaurus crenatissimus: Carrano 2007). In contrast to some ceratosaurians (e.g. Carnotaurus sastrei: MACN-Pv-CH 894; Ceratosaurus nasicornis: Gilmore 1920; Elaphrosaurus bambergi Janensch, 1920: Rauhut and Carrano 2016; Limusaurus inextricabilis Xu et al., 2009: IVPP V15924; Majungasaurus crenatissimus: Carrano 2007), there is no fossa dorsal to the glenoid. The anterior edge of the posterior region of the proximal end continues gradually to the acromial area. The acromial process is well developed dorsally and has an acute apex, decreasing its thickness proximally from the base of the scapular blade, resembling the condition in allosauroids (e.g. Allosaurus fragilis: Madsen 1976a; Sinraptor dongi: Currie and Zhao 1993), but not ceratosaurians, in which this process is more robust (e.g. Ceratosaurus dentisulcatus: Madsen and Welles 2000; Ceratosaurus nasicornis: Gilmore 1920). This process is more clearly separated from the scapular blade in Herrerasaurus ischigualastensis Reig, 1963 (Sereno 1994), forming an angle of <90°,and is flatter and less pronounced in Chilesaurus diegosuarezi (Novas et al. 2015), Dilophosaurus wetherilli (Marsh and Rowe 2020), and megalosauroids (e.g. Eustreptospondylus oxoniensis Walker, 1964: Sadleir et al. 2008; Megalosaurus bucklandii: Benson 2010). In lateral view, the subacromial depression occurs between the acromial process and the articular surface for the coracoid. This depression is subtriangular, concave, and extends anteroposteriorly along most of the proximal end of the bone. The depth of this depression decreases towards the coracoid suture.
The scapular blade is relatively straight with nearly parallel edges in lateral view. The anterior margin bears a thin longitudinal ridge, which has been interpreted in other theropod species as the correlate of the insertion of the m. levator scapulae and m. trapezius (Jasinoski et al. 2006, Burch 2014). The anteroposteriorly narrowest level of the blade is immediately above the glenoid–acromial region, and it expands slightly anteriorly and posteriorly up to the distal part of the bone, resembling Allosaurus fragilis (Madsen 1976a). This strap-like blade is usual in early averostrans (e.g. Allosaurus fragilis: Madsen 1976a; Carnotaurus sastrei: MACN-Pv-CH 894; Ceratosaurus nasicornis: Gilmore 1920; Chilesaurus diegosuarezi: Novas et al. 2015; Megalosaurus bucklandii: Benson 2010) and differs from coelophysoids (e.g. Coelophysis bauri Cope, 1887: Colbert 1989; Liliensternus liliensterni von Huene, 1934: von Huene 1934) and Dilophosaurus wetherilli (Marsh and Rowe 2020), which have a pronounced expansion at the distal end of the blade. In contrast to non-tetanuran theropods (e.g. Carnotaurus sastrei: MACN-Pv-CH 894; Ceratosaurus nasicornis: Gilmore 1920; Dilophosaurus wetherilli: Marsh and Rowe 2020; Eoabelisaurus mefi: MPEF-PV 3390; Majungasaurus crenatissimus: Carrano 2007), the scapular blade of Piatnitzkysaurus floresi is proportionally anteroposteriorly narrower, as in allosauroids (e.g. Allosaurus fragilis: Madsen 1976a; Sinraptor dongi: Currie and Zhao 1993). Its transverse thickness decreases from proximal to distal. In medial view, the surface of the blade is smooth, with some striations immediately distal to the posterior region of the proximal end. The proximal third of the scapular blade possesses a low and relatively wide medial central ridge, which becomes wider distally and might mark the origin of the m. subscapularis (Jasinoski et al. 2006, Burch 2014). The scapula is flexed medially towards its anterior end, as in allosauroids (e.g. Allosaurus fragilis: Madsen 1976a), megalosauroids (e.g. Eustreptospondylus oxoniensis: Sadleir et al. 2008; Megalosaurus bucklandii: Benson 2010), and Chilesaurus diegosuarezi (Novas et al. 2015). This curvature is much less pronounced in ceratosaurians (e.g. Ceratosaurus nasicornis: Gilmore 1920) and some non-tetanuran saurischians (e.g. Dilophosaurus wetherilli: Marsh and Rowe 2020; Herrerasaurus ischigualastensis: Sereno 1994). Above the posterior region of the proximal end, the thickness of the proximoposterior edge increases. In medial view, there is a thickening of the blade that divides the proximal surface into two medial depressions, one subtriangular dorsally and another elongated ventrally. The latter depression probably marks the origin of the m. scapulohumeralis posterior (Burch 2014).
Coracoid: Both coracoids are preserved in the holotype (PVL 4073). The right element is missing the anterodorsal and anteroventral corners, and the left one is represented only by its posteroproximal region (Fig. 2). The bone is anteroposteriorly longer than dorsoventrally tall, being suboval in lateral view, similar to that in allosauroids (e.g. Allosaurus fragilis: Madsen 1976a; Yangchuanosaurus hepingensis Gao, 1992: Gao 1992) and megalosauroids (e.g. Megalosaurus bucklandii: Benson 2010). It differs from some non-averostran theropods, such as Dilophosaurus wetherilli (Marsh and Rowe 2020), in which the general shape of the bone is subquadrangular or subrectangular, with less curved edges, in lateral/medial views. On the posterodorsal side, the coracoid glenoid region is preserved. The contribution of the coracoid to the glenoid fossa faces dorsolaterally and is bounded by a thick subglenoid lip. This thickened edge continues ventrally on the lateral surface, giving rise to the infraglenoid buttress. Immediately below the subglenoid lip, the posterior margin curves to result in a considerably expanded posterior process. On the lateral surface, this area is surrounded by a broad and thick irregular rim projected from the infraglenoid buttress to the pointed end of the posterior process. A concave notch is also present in some theropods of different groups (e.g. Allosaurus fragilis: Madsen 1976a; Limusaurus inextricabilis: IVPP V 15924; Xuanhanosaurus qilixiaensis: Dong 1984), although the process is more rounded than in Allosaurus fragilis and Limusaurus inextricabilis. In posterior view, the posterior margin of the concavity is slightly thickened, and there is a subspheric concavity that extends anteroposteriorly on the medial surface. The entire medial surface is appreciably concave, although it becomes slightly less concave anteriorly. In contrast, the lateral surface of the bone is moderately convex. Below the infraglenoid buttress, on the lateral surface of the bone and at mid-height of the rim that surrounds the posterior concavity, there is the bicipital tubercle. This tubercle is a subtriangular prominence as in non-tetanuran neotheropods (e.g. Coelophysis bauri: Rinehart et al. 2009; Liliensternus liliensterni: Ezcurra and Cuny 2007; Zupaysaurus rougieri: PULR-V 076) and differs from Ceratosaurus dentisulcatus (Madsen and Welles 2000) and Dilophosaurus wetherilli (Marsh and Rowe 2020), in which it is more rounded. The tubercle becomes sharper dorsally as a short ridge, resembling the condition in allosauroids (e.g. Allosaurus fragilis: Madsen 1976a), although it is less pronounced. This prominence is absent in Baryonyx walkeri (Charig and Milner 1997), Chilesaurus diegosuarezi (Novas et al. 2015), and Megalosaurus bucklandii (Benson 2010). The posteroventral region of the thickened rim between the posterior margin and the bicipital tubercle might have been associated with the insertion of the m. biceps and/or m. coracobrachialis brevis (Jasinoski et al. 2006, Burch 2014).
In dorsal view, the region that articulates with the scapula is thick posteriorly, as in Allosaurus fragilis (Madsen 1976a) and Dilophosaurus wetherilli (Marsh and Rowe 2020), and it has a depression that expands over the medial surface of the bone. The thickness of this region decreases abruptly ventrally and anteriorly. Both coracoids lack their most anterior regions. The ventral margin of the coracoid is regularly rounded, slightly thickened from the broken most anterior region to the posterior process. The coracoid foramen opens from the lateral side, immediately above the centre of the lateral surface, traversing the bone to the medial surface. As in Ceratosaurus dentisulcatus (craniodorsally; Madsen and Welles 2000), Majungasaurus crenatissimus (craniodorsally; Carrano 2007), and Dilophosaurus wetherilli (posterodorsally; Marsh and Rowe 2020), the foramen is inclined dorsally, in contrast to Allosaurus fragilis (Madsen 1976a) and Megalosaurus bucklandii (Benson 2010), in which the foramen is inclined posteromedially. The coracoid foramen is relatively large, being larger on the lateral side than on the medial one, resembling the condition in Allosaurus fragilis (Madsen 1976a). In contrast, the foramen continues as a groove on the medial surface in Ceratosaurus dentisulcatus (Madsen and Welles 2000), Majungasaurus crenatissimus (Carrano 2007), and Dilophosaurus wetherilli (Marsh and Rowe 2020).
Forelimb
Humerus: The right humeri of the holotype (PVL 4073; Fig. 3) and the referred specimen (MACN-Pv-CH 895) are almost complete and well preserved; the edge of the deltopectoral crest is slightly damaged in the holotype, and the anterior surface of the radial condyle is not preserved in the referred specimen. The humerus of Piatnitzkysaurus floresi differs from abelisaurids (e.g. Carnotaurus sastrei: MACN-Pv-CH 894; Majungasaurus crenatissimus: Carrano 2007), in which the humerus is columnar and shorter, and non-averostran saurischians (Dilophosaurus wetherilli: Marsh and Rowe 2020; Herrerasaurus ischigualastensis: MACN-Pv 18060; Liliensternus liliensterni: HMN BM R 2175), in which the bone is more gracile. The overall morphology of the humerus of Piatnitzkysaurus floresi resembles that of allosauroids (e.g. Allosaurus fragilis: Madsen 1976a), Asfaltovenator vialidadi (MPEF-PV 3440), and megalosauroids (e.g. Megalosaurus bucklandii: Benson 2010), but the humeral shaft is considerably less straight in the former species. It has a markedly sigmoid profile in anteroposterior view that is present in only a few theropods (e.g. Allosaurus fragilis: Madsen 1976a). The ratio of length to minimum circumference is ~8.5. As is common in theropods, the humerus is transversely expanded both proximally and, less conspicuously, distally. In abelisaurids, the expansion of the proximal end is less pronounced (e.g. Carnotaurus sastrei: MACN-Pv-CH 894; Majungasaurus crenatissimus: Carrano 2007), whereas it is more developed in spinosauroids (Baryonyx walkeri: Charig and Milner 1997). The long axes of both proximal and distal ends are twisted at ~60° relative to each other, more than in Chilesaurus diegosuarezi (Novas et al. 2015) and ceratosaurians (e.g. Carnotaurus sastrei: MACNPv-CH 894; Ceratosaurus dentisulcatus: Madsen and Welles 2000; Majungasaurus crenatissimus: Carrano 2007; Limusaurus inextricabilis: IVPP V 15924), but similar to allosauroids (e.g. Allosaurus fragilis: Madsen 1976a), Asfaltovenator vialidadi (MPEF-PV 3440), and megalosauroids (e.g. Eustreptospondylus oxoniensis: Sadleir et al. 2008, Megalosaurus bucklandii: Benson 2010). In lateral and medial views, the humeral shaft is particularly sigmoid and is more bowed anteriorly than in ceratosaurians (e.g. Carnotaurus sastrei: MACN-Pv-CH 894; Ceratosaurus dentisulcatus: Madsen and Welles 2000; Majungasaurus crenatissimus: Carrano 2007), allosauroids (e.g. Allosaurus fragilis: Madsen 1976a), Asfaltovenator vialidadi (MPEF-PV 3440), megalosauroids (e.g. Eustreptospondylus oxoniensis: Sadleir et al. 2008, Megalosaurus bucklandii: Benson 2010), and spinosauroids (Baryonyx walkeri: Charig and Milner 1997). This sigmoid profile is also present in Dilophosaurus wetherilli (Marsh and Rowe 2020), although it is less pronounced. The proximal end has three prominent protuberances with rough surfaces. The humeral head is positioned at mid-width on the proximal end and has an oval and bulbous shape, extending slightly anteriorly. The greater tubercle is developed laterally to the humeral head, which has a subrectangular shape in proximal view and a slight posterior orientation in lateral view. The greater tubercle reduces its thickness and increases its orientation laterally, giving rise to the deltopectoral crest. Medially to the humeral head is the internal tuberosity, which, like the greater tubercle, is proportionally smaller than the humeral head. The internal tuberosity is proportionally larger than in Dilophosaurus wetherilli (Marsh and Rowe 2020) and abelisaurids (e.g. Carnotaurus sastrei: MACNPv-CH 894; Majungasaurus crenatissimus: Carrano 2007). It is rounded in proximal view and thicker than the greater tubercle, being subcircular in anteroposterior view. The main axes of the humeral head and the internal tuberosity are offset from each other, resulting in an obtuse angle between both structures on the posterior margin of the proximal end. Distal to the contact between the humeral head and the internal tuberosity there is a shallow depression that might mark the insertion of the m. scapulohumeralis anterior and/or posterior (Jasinoski et al. 2006, Burch 2014).
The deltopectoral crest emerges anteriorly from the lateral edge of the proximal half of the bone and is more developed than in non-tetanuran theropods (e.g. Dilophosaurus wetherilli: Marsh and Rowe 2020) and Chilesaurus diegosuarezi (Novas et al. 2015). On the lateral side, behind the deltopectoral crest, there is a proximodistally expanded shallow depression. This depression might indicate the attachment of the m. deltoideus clavicularis (Jasinoski et al. 2006, Lipkin and Carpenter 2008, Burch 2014). Posterior to this depression there is an extended concave region that could mark the origin of the m. triceps brachii longus, and distal to this region, on the lateral surface of the deltopectoral crest, there is an elongated scar parallel to the margin that probably served as the insertion for m. humeroradialis (Jasinoski et al. 2006, Lipkin and Carpenter 2008, Burch 2014). The deltopectoral crest is subtriangular in lateral view and maintains a relatively constant thickness towards the distal end. The edge of the crest possesses traces probably for the insertion of the m. supracoracoideus (Jasinoski et al. 2006, Lipkin and Carpenter 2008, Burch 2014). On the anterior side and below the proximal protuberances, there is a concave region expanded from the base of the deltopectoral crest, where the insertion of m. coracobrachialis has been interpreted (Jasinoski et al. 2006, Lipkin and Carpenter 2008, Burch 2014). On the medial side of the bone at mid-height of the shaft, there is an oval deep nutrient foramen.
The distal end of the bone has a radial condyle on the lateral side and an ulnar condyle on the medial side. Both condyles are oriented mostly anteriorly, whereas the surface is smoother on the posterior face. These condyles are bulbous and prominent, whereas Ceratosaurus dentisulcatus (Madsen and Welles 2000) and Limusaurus inextricabilis (IVPP V 15924) have flattened condyles, and in abelisaurids the condyles are reduced and flattened (e.g. Carnotaurus sastrei: MACN-Pv-CH 894; Majungasaurus crenatissimus: Carrano 2007). In distal view, the ulnar condyle is transversely broader and subrectangular, while the radial condyle is subcircular. The medial margin of the ulnar condyle is thickened as a lip. On the lateral surface of the radial condyle, a low ridge emerges and extends proximally parallel to the main axis of the bone. A broad subcircular fossa occurs on the mid-width of the anterior surface of the distal end. In posterior view, the distal end is flat to slightly concave transversally.
Ulna: The complete left ulna of the holotype is preserved (PVL 4073: Fig. 4). It is elongated, shorter than the humerus (0.5 ratio including the olecranon process). The ulna:humerus length ratio in Piatnitzkysaurus issimilartothatinsomeearlyaverostrantheropods (e.g. Asfaltovenator vialidadi: MPEF-PV 3440; Eoabelisaurus mefi: MPEF-PV 3390; Torvosaurus tanneri: Galton & Jensen, 1979: Galton and Jensen 1979), but less than in Dilophosaurus wetherilli (Marsh and Rowe 2020). The ulna has a rough surface with many irregular fractures and is more robust than in non-averostran theropods (e.g. Dilophosaurus wetherilli: Marsh and Rowe 2020; Dracoraptor hanigani Martill et al., 2016: Martill et al. 2016) and less than in megalosauroids (e.g. Megalosaurus bucklandii: Benson 2010; Torvosaurus tanneri: Galton and Jensen 1979), being similar to the bone in allosauroids (e.g. Allosaurus fragilis: Madsen 1976a). The ulna of Piatnitzkysaurus floresi is slightly expanded distally and markedly expanded proximally. At the proximal end, the olecranon process is developed as a large, semi-spherical, prominent protuberance on the posterior half. This process is more prominent in Baryonyx walkeri (Charig and Milner 1997) and Eoabelisaurus mefi (MPEF-PV 3390), and is squarer in Dilophosaurus wetherilli (Marsh and Rowe 2020). The anterolateral process is less developed than in ceratosaurians (e.g. Ceratosaurus nasicornis: Carrano and Choniere 2016), and it emerges from the lateral margin of the base of the olecranon process, continuing distally as a subtriangular protuberance on the lateral surface of the bone. Anteriorly to the olecranon process there is the facet for the humeral articulation, which is concave and anteroposteriorly extended. Expanded anteriorly from the facet is the anteromedial process, smaller than the olecranon process. On the lateral surface is the radial articulation, immediately below the humeral articulation of the proximal end, and distally is a large anteroposterior fracture. This articulation is smooth and triangular. In contrast to some early averostran theropods (e.g. Ceratosaurus nasicornis: Carrano and Choniere 2016; Megalosaurus bucklandii: Benson 2010), the ulna of Piatnitzkysaurus floresi lacks any ridge on the anterior, lateral, or distal surfaces of the shaft.
The expansion of the distal end is bulbous and sub-elliptical in distal view. In side view, both anterior and posterior margins are distinctly convex, although the anterior one is more curved. In anteroposterior view, the margins are straight, although they slope medially in the distal region. The radial articulation occurs on the anterolateral side of the distal end and is adjacent to the distal edge. This articular surface is flat and subcircular. In medial view, a process for ligamentous insertion is present at the distal end.
Pelvic girdle
Ilium: Most of the left ilium is preserved in the referred specimen (MACN-Pv-CH 895: Fig. 5). There is also a fragment of another referred left ilium that corresponds to the ischial peduncle and the dorsal rim of the acetabulum. The posterior fragment of the postacetabular process of the right ilium is preserved in the holotype (PVL 4073: Fig. 5). The overall anteroposteriorly elongated morphology of the ilium resembles that in most non-avian theropods (e.g. Allosaurus fragilis: Madsen 1976a; Carnotaurus sastrei: MACN-Pv-CH 894; Ceratosaurus nasicornis: Gilmore 1920; Megapnosaurus rhodesiensis Raath, 1969: Raath 1977; Dilophosaurus wetherilli: Marsh and Rowe 2020; Ichthyovenator laosensis Allain et al., 2012: Allain et al. 2012; Mapusaurus roseae Coria & Currie, 2006: Coria and Currie 2006; Megalosaurus bucklandii: Benson 2010; Tyrannosaurus rex Osborn, 1905: Brochu 2003). In lateral view, the preserved dorsal margin of the iliac blade is slightly convex and has numerous dorsoventrally oriented ridges, especially along the anterodorsal edge. These ridges probably correspond to the attachment of the mm. iliotibiales or homologous muscles (Hutchinson 2001a, Carrano and Hutchinson 2002, Lacerda et al. 2024). The lateral surface of the iliac blade is divided into anteroposteriorly similar halves by a short median vertical ridge, which delimits two shallow but extensive depressions immediately anteriorly and posteriorly to it. The anterior depression is likely to mark the origin for the m. iliofemoralis externus, and the posterior one is the probable correlate of the origin of the m. iliofibularis (Hutchinson 2001a, Carrano and Hutchinson 2002, Lacerda et al. 2024). In the most complete ilium, the blade is broken at the anterior and posterior ends, but it can be determined that the base of the preacetabular process is dorsoventrally higher than the base of the postacetabular one. In dorsal view, the iliac blade slightly arches medially. The preserved anterior end of the iliac blade gradually narrows anteriorly, while the blade increases its thickness at its posteriormost preserved region. The medial surface has a slightly roughened surface with some irregular regions with prominences and depressions at mid-height and dorsal to the peduncles. These surfaces represent the attachment surfaces for the sacral ribs and transverse processes.
The pubic peduncle is larger than the ischial one, as is usual in tetanuran theropods (e.g. Allosaurus fragilis: Madsen 1976a; Baryonyx walkeri: Charig and Milner 1997; Condorraptor currumili: MPEF-PV 1687; Megalosaurus bucklandii: Benson 2010; Sinraptor dongi: Currie and Zhao 1993), in contrast to most non-tetanurans, in which both peduncles are subequal (e.g. Megapnosaurus rhodesiensis: Raath 1977; Dilophosaurus wetherilli: Marsh and Rowe 2020; Rajasaurus narmadensis Wilson et al., 2003: Wilson et al. 2003; Vespersaurus paranaensis Langer et al., 2019: Langer et al. 2019). The ischial peduncle is posteroventrally projected and articulated on a depressed articular surface on the ischium, as is usual in tetanurans (e.g. Allosaurus fragilis: Madsen 1976a; Megalosaurus bucklandii: Benson 2010; Sinraptor dongi: Currie and Zhao 1993) and some ceratosaurian theropods (e.g. Majungasaurus crenatissimus: Carrano 2007; Masiakasaurus knopfleri Sampson et al., 2001: Sampson et al. 2001). In ventral view, the surface of articulation of both pubic and ischial peduncles is rough and subtriangular, although that of the ischial peduncle is smaller. A preacetabular notch separates the pubic peduncle from the base of the preacetabular process. Anteroventrally from the preacetabular process there is a shallow fossa that could mark the origin of the m. iliofemoralis internus (Carrano and Hutchinson 2002, Lacerda et al. 2024). Although the anterior region of the iliac blade is broken, this notch seems to resemble the condition in most tetanuran theropods (e.g. Allosaurus fragilis: Madsen 1976a; Ichthyovenator laosensis: Allain et al. 2012; Mapusaurus roseae: Coria and Currie 2006; Megalosaurus bucklandii: Benson 2010; Sinraptor dongi: Currie and Zhao 1993), in contrast to non-tetanuran theropods (Ceratosaurus nasicornis: Gilmore 1920; Dilophosaurus wetherilli: Marsh and Rowe 2020; Sarcosaurus woodi Andrews, 1921: Ezcurra et al. 2021), in which this notch is narrower in lateral view. In posterior view, the ventral surface of the widened iliac blade possesses a relatively narrow and deep brevis fossa, where the lateral margin (= brevis shelf) is thicker than the medial one. On lateral view, the postacetabular process ends quadrangularly posteriorly. Posterodorsally to the ischial peduncle, the medial margin of the brevis fossa originates and is exposed in lateral view. The supraacetabular crest reaches its maximum lateral development dorsally to the acetabular rim and projects slightly lateroventrally. This crest extends over most of the pubic peduncle and slightly over the base of the ischial peduncle, but it is not connected to the brevis shelf, contrasting with some non-tetanuran theropods (e.g. Ceratosaurus nasicornis: Gilmore 1920; Dilophosaurus wetherilli: Marsh and Rowe 2020; Eoabelisaurus mefi: MPEF-PV 3990). A foramen is present on the anterodorsal region of the lateral surface of the pubic peduncle, as in Allosaurus fragilis (Madsen 1976a), whereas Megalosaurus bucklandii has two foramina in this region (Benson 2010). Another foramen is present on the posteroventral side of the median vertical ridge, as in Condorraptor currumili (MPEF-PV 1687), in contrast to Allosaurus fragilis (Madsen 1976a) and Megalosaurus bucklandii (Benson 2010), which have two foramina. A third foramen is present close to the base of the referred fragmentary ischial peduncle on its lateral surface, as in Condorraptor currumili (MPEF-PV 1687) and Megalosaurus bucklandii (Benson 2010). There are no signs of fusion between the pelvic girdle elements, in contrast to several non-tetanuran theropods (e.g. Megapnosaurus rhodesiensis: Raath 1977; Carnotaurus sastrei: MACN-Pv-CH 894; Ceratosaurus nasicornis: Gilmore 1920; Eoabelisaurus mefi: MPEF-PV 3990).
Pubis: The complete right pubis and the proximal and distal ends of the left pubis are preserved in the holotype (PVL 4073: Fig. 6), while both proximal ends are preserved in the referred specimen (MACN-Pv-CH 895: Fig. 7). The pubis is elongated and expanded at its proximal and distal ends. The general morphology resembles that of most non-coelurosaurian neotheropods (e.g. Carnotaurus sastrei: MACN-Pv-CH 894; Ceratosaurus nasicornis: Gilmore 1920; Condorraptor currumili: MPEF-PV 1696; Eustreptospondylus oxoniensis: Sadleir et al. 2008; Marshosaurus bicentesimus: Madsen 1976b; Monolophosaurus jiangi Zhao & Currie, 1993: Zhao and Currie 1993; Sinraptor dongi: Currie and Zhao 1993). In the proximal end, the articular facet for the ilium is irregular, relatively flat, and ovoid in dorsal view. Posterior to this facet, there is a slightly more inclined and smaller non-articular surface that contributes to the acetabulum. The facet for contact with the ischium is in the posterior region of the proximal end. This facet is less extended than that of the contact with the ilium, being subtriangular and relatively flat. It forms an angle of ~110° with the surface that contributes to the acetabulum. The pubic plate preserves the obturator foramen, which has a maximum diameter of 3.15 cm. The contour and size of this foramen resemble those of some non-tetanuran (e.g. Cryolophosaurus ellioti Hammer & Hickerson, 1994: Smith et al. 2007; Dilophosaurus wetherilli: Marsh and Rowe 2020; Herrerasaurus ischigualastensis: PVL 2566), early tetanuran (e.g. Condorraptor currumili: MPEF-PV 1696), and ceratosaurian theropods (e.g. Carnotaurus sastrei: MACN-Pv-CH 894; Ceratosaurus nasicornis: Gilmore 1920; Eoabelisaurus mefi: MPEF-PV 3990). In contrast, the obturator foramen is ventrally open, forming a notch, in allosauroids (e.g. Allosaurus fragilis: Madsen 1976a; Giganotosaurus carolini Coria & Salgado, 1995: Coria and Salgado 1995; Sinraptor dongi: Currie and Zhao 1993) and spinosaurids (e.g. Ichthyovenator laosensis: Allain et al. 2012) (Hutchinson 2001a). In the case of coelophysoids, another foramen could be present in the pubic plate (i.e. pubic fenestra) (e.g. Megapnosaurus rhodesiensis: Raath 1977; Segisaurus halli Camp, 1936: Carrano et al. 2005; Pendraig milnerae Spiekman et al., 2001: Spiekman et al. 2021).
The pubic apron originates at the posteromedial edge of the proximal end of the bone and shifts gradually towards the medial edge along the proximal region of the shaft, placed at the anterior margin of the medial side as in Condorraptor currumili (MPEF-PV 1696). The apron is more extended medially after reaching the medial edge, then decreases its width towards the distal end. Ventrally to the proximal end, the edge of the apron is slightly inclined posterodorsally in medial view. At the proximal end, the medial and lateral surfaces are rough and striated. The pubic tuberosity is positioned lateroventrally to the iliac facet, on a slightly elevated surface. This tuberosity might mark the attachment of the m. ambiens (Hutchinson 2001a, Carrano and Hutchinson 2002, Lacerda et al. 2024). The pubic shaft (excluding the apron) is anteroposteriorly deeper, as in some Jurassic theropods (e.g. Condorraptor currumili: MPEF-PV 1696; Dilophosaurus wetherilli: Marsh and Rowe 2020; Sinraptor dongi: Currie and Zhao 1993) and is relatively straight in both anterior and lateral views, which differs from the rod-like and posteriorly curved pubic shaft of coelophysoids and Notatesseraeraptor frickensis Zahner & Brinkmann, 2019 (Raath 1977, Rinehart et al. 2009, Zahner and Brinkmann 2019).
The distal end expands anteroposteriorly and is bootlike, as in most averostran theropods. This expansion is less anteroposteriorly developed than in most allosauroids (e.g. Acrocanthosaurus atokensis Stovall & Langston, 1950: Stovall and Langston 1950; Allosaurus fragilis: Madsen 1976a; Giganotosaurus carolini: Coria and Salgado 1995), coelurosaurs (Brochu 2003, Rhodes and Currie 2020), and some ceratosaurians (e.g. Carnotaurus sastrei: MACN-Pv-CH 894; Ceratosaurus nasicornis: Gilmore 1920), although it is more developed than in non-averostran neotheropods (coelophysoids: Raath 1977, Rinehart et al. 2009; Dilophosaurus wetherilli: Marsh and Rowe 2020; Notatesseraeraptor frickensis: Zahner and Brinkmann 2019). The anterior edge of the distal end is relatively straight in lateromedial view, whereas the posterior edge is more curved. A low ridge develops as a continuation of the pubic apron on the anterior surface of the distal expansion.There seems to be an oval opening above the pubic boot, between the pubic apron and the mentioned ridge. In ventral view, the distal end is subrectangular, anteroposteriorly longer than broad, and has a rough surface. The pubes probably contacted each other because of the presence of a flat and striated surface on the medial side of the distal end of the bones and the overall curvature of the shaft, which curves medially towards the distal end.
Ischium: Most of both ischia are preserved in the holotype (PVL 4073: Fig. 8), while the proximal and distal ends of the right ischium, and the iliac peduncle and the distal end of the left one are preserved in the referred specimen (MACNPv-CH 895: Fig. 9). The ischium has the typical Y-shaped outline present in most non-coelurosaurian theropods (e.g. Allosaurus fragilis: Madsen 1976a; Dilophosaurus wetherilli: Marsh and Rowe 2020; Ichthyovenator laosensis: Allain et al. 2012; Mapusaurus roseae: Coria and Currie 2006; Marshosaurus bicentesimus: Madsen 1976b) and is relatively more elongated than in most coelurosaurian theropods (e.g. Archaeopteryx lithographica Meyer, 1861: Ostrom 1976; Tyrannosaurus rex: Brochu 2003; non-avian maniraptorans: Rhodes et al. 2021). The iliac peduncle is more robust and wider than the pubic one, although the latter is more elongated, resembling the condition in tetanuran theropods (e.g. Allosaurus fragilis: Madsen 1976a; Alpkarakush kyrgyzicus Rauhut et al., 2024: Rauhut et al. 2024; Baryonyx walkeri: Charig and Milner 1997, Eustreptospondylus oxoniensis: Sadleir et al. 2008; Monolophosaurus jiangi: Zhao and Currie 1993; ‘ Szechuanosaurus ’ zigongensis Gao, 1993: Gao 1993). Both peduncles are flat to concave on the medial side, and both are transversally convex on their lateral surface. The proximal end is distinctly laterally displaced from the shaft in the referred specimen (MACN-Pv-CH 895). This was probably caused by a welded fracture in life (see discussion below). The articular facet for the pubis is relatively flat, although it has probably been polished during preparation, whereas the facet for the ilium is more irregular. The latter has a depression that extends from the centre of the facet to its posterior edge. The acetabular rim is subcircular in lateral view and convex lateromedially. The contribution to the acetabulum is greater than in the case of the pubis. The posterior surface of the iliac peduncle is sharp. The obturator process is positioned distally to the pubic peduncle. Although it is poorly preserved, the natural margins of the process could indicate a broad proximal notch adjacent to the pubic peduncle, resembling the condition in Allosaurus fragilis (Madsen 1976a) and Sinraptor dongi (Currie and Zhao 1993). This process continuous as a very low ridge distally that rotates to the medial side of the shaft towards the distal end, resembling the condition of many tetanuran theropods (e.g. Allosaurus fragrilis: Madsen 1976a; Mapusaurus roseae: Coria and Currie 2006; Megalosaurus bucklandii: Benson 2010). This ridge is apparently less developed in Piatnitzkysaurus floresi than in Allosaurus fragilis (Madsen 1976a), Mapusaurus roseae (Coria and Currie 2006), and Megalosaurus bucklandii (Benson 2010), although this ridge is severely damaged in the available specimens of Piatnitzkysaurus floresi. In contrast, the obturator process usually does not continue as a ridge in non-tetanuran theropods (e.g. Carnotaurus sastrei: MACN-Pv-CH 894; Cryolophosaurus ellioti: Smith et al. 2007; Eoabelisaurus mefi: MPEF-PV 3990). Ventral to the obturator process there is not a notch separating the ventral end of the process from the ischial shaft, as in non-tetanuran theropods (e.g. Dilophosaurus wetherilli: Marsh and Rowe 2020; Tachiraptor admirabilis Langer et al., 2014: Langer et al. 2014), although there is some uncertainty owing to the preservation of the obturator process.
The ischial shaft is triangular in cross-section. It has a rough flat medial surface with shallow grooves, especially at its distal third, indicating the probable contact with its counterpart. There is a shallow groove on the medial surface of the transition between the shaft and the proximal end. As in most neotheropods, the ischial shaft is mainly straight in lateral view, while it is laterally curved at its proximal third in anteroposterior view. A mound-like expansion on the posteroventral surface of the iliac peduncle is homologous to the ischial tubercle (i.e. ischial tuberosity: Hutchinson 2001a), which is present in most theropods (e.g. Acrocanthosaurus atokensis: Stovall and Langston 1950; Concavenator corcovatus Ortega et al., 2010: Cuesta et al. 2018; Cryolophosaurus ellioti: Smith et al. 2007; Megalosaurus bucklandii: Benson 2010; Sinraptor dongi: Currie and Zhao 1993; Tyrannosaurus rex: Brochu 2003). A proximodistally oriented tubercle is present on the posterolateral surface of the ischial shaft, close to the distal end. The distal end is slightly expanded anteroposteriorly and has a subcircular profile in lateral view, similar to the condition in some allosauroids (Allosaurus fragilis: Madsen 1976a; Giganotosaurus carolini: Coria and Salgado 1995; Mapusaurus roseae: Coria and Currie 2006) and non-tetanuran theropods (Cryolophosaurus ellioti: Smith et al. 2007; Dilophosaurus wetherilli: Marsh and Rowe 2020). In contrast, the distal end is usually more expanded anteroposteriorly in Alpkarakush kyrgyzicus (Rauhut et al. 2024), ‘ Szechuanosaurus ’ zigongensis (Gao 1993), and ceratosaurian theropods (Carnotaurussastrei: MACN-Pv-CH 894; Ceratosaurusnasicornis: Gilmore 1920). The distal end is asymmetrical in lateral and medial views, in which the anterior region is pointed, whereas the posterior one is more rounded and shorter. In ventral view, the distal end is ovoid and has a rough surface.
The referred specimen of Piatnitzkysaurus floresi MACNPv-CH 895 possesses a deformation in the proximal region of the right ischium. The shaft is elevated, being misaligned from its counterpart. This deformation could have been produced by a partial fracture of the bone (given that it is continuous, without a fracture line on part of the surface) in life and it never healed. In this case, the injury would have been related to the death of the specimen. However, this deformation is probably attributable to taphonomic processes that occurred post-mortem of the specimen.
Hindlimb
Femur: Both femora are preserved in the holotype (PVL 4073: Fig. 10), and the left femur is preserved in the referred specimen (MACN-Pv-CH 895: Fig. 11). The orientation and shape of the femur mentioned in this description are based principally on the right femur of the holotype, because it seems less affected by diagenetic processes. The bone is long and relatively robust, similar to Condorraptorcurrumili (MPEF-PV 1690–1691), Eoabelisaurus mefi (MPEF-PV 3990), and Berberosaurus liassicus Allain et al., 2007 (Allain et al. 2007), but being more gracile than in bigger theropods, such as Allosaurus fragilis (MACN-Pv 18453a), Giganotosaurus carolini (MUCPv-CH-1), Tyrannosaurus rex (Osborn 1905), and Tyrannotitan chubutensis Novas et al., 2005 (MPEF-PV 1156). The main axis of the proximal end is twisted ~20° with respect to the transverse axis of the distal end, being anteromedially oriented, similar to the condition in several other early averostrans, such as Megalosaurus bucklandii (Benson 2010), Eoabelisaurus mefi (MPEF-PV 3990), and Ceratosaurus dentisulcatus (Madsen and Welles 2000). The femur is relatively straight in anteroposterior view, although the proximal half is slightly convex laterally, resembling the condition in many non-tetanuran theropods (e.g. Ceratosaurus dentisulcatus: Madsen and Welles 2000; Dilophosaurus wetherilli: Marsh and Rowe 2020; Koleken inakayali Pol et al., 2024: Pol et al. 2024; Liliensternus liliensterni: HMN BM R 2175; Megapnosaurus rhodesiensis: Raath 1977). In contrast, the femur is straighter in most tetanuran theropods (e.g. Allosaurus fragilis: MACNPv18453a; Megalosaurus bucklandii: Benson 2010; Sinraptor dongi: Currie and Zhao 1993; Tyrannosaurus rex: Brochu 2003; Tyrannotitan chubutensis: MPEF-PV 1156). In lateral view, the femur is slightly sigmoid; the proximal half is convex posteriorly, whereas the distal half is slightly convex anteriorly, similar to the condition in some allosauroids (e.g. Allosaurus fragilis: MACN-Pv 18453a; Alpkarakush kyrgyzicus: Rauhut et al. 2024; Sinraptor dongi: Currie and Zhao 1993), whereas it is more curved in some non-tetanuran theropods (e.g. Koleken inakayali: Pol et al. 2024; Liliensternus liliensterni: HMN BM R 2175; Megapnosaurus rhodesiensis: Raath 1977). The femoral head is oval in proximal view, with a rough surface. There are three distinct tubercles on the femoral head. The posterior tubercle extends along most of the posterior border of the proximal end, while the anterior tubercle expands anteromedially. The posteromedial tubercle is low and curves posteriorly at the proximal end, forming a hook-shaped ridge. This ridge delimits a proximodistally oriented groove on the posterior surface of the femoral head, as occurs in most neotheropods (e.g. Allosaurus fragilis: Madsen 1976a; Berberosaurus liassicus: Allain et al. 2007; Eoabelisaurus mefi: MPEF-PV 3990; Sinraptor dongi: Currie and Zhao 1993), but this groove is shallower in Dilophosaurus wetherilli (Marsh and Rowe 2020), Liliensternus liliensterni (HMN BM R 2175), and coelophysoids (e.g. Coelophysis bauri: Rinehart et al. 2009; Megapnosaurus rhodesiensis: Raath 1977). This hook-shaped posteromedial tubercle is slightly more developed than in allosauroids (e.g. Allosaurus fragilis: Madsen 1976a; Giganotosaurus carolini: MUCPv-CH-1; Tyrannotitan chubutensis: MPEF-PV 1156) and contacts the posterior tubercle on the posterior side. The greater trochanter extends along the posterolateral edge of the proximal end as a thick, proximodistally oriented ridge. A proximodistally ovoid, rugose mound-like process is present anteriorly to the greater trochanter and probably represents the insertion of the m. puboischiofemoralis externus (Carrano and Hutchinson 2002, Smith 2021). On the anterior face, close to the proximal end, the anterior trochanter (= lesser trochanter) arises, which is more developed than in non-tetanuran theropods (e.g. Berberosaurus liassicus: Allain et al. 2007; Carnotaurus sastrei: MACN-Pv-CH 894; Ceratosaurus dentisulcatus: Madsen and Welles 2000; Dilophosaurus wetherilli: Marsh and Rowe 2020; Liliensternus liliensterni: HMN BM R 2175; Tawa hallae Nesbitt et al., 2009: Nesbitt et al. 2009), but it is lower than in coelurosaurs (e.g. Archaeopteryx lithographica: Ostrom 1976; Tyrannosaurus rex: Brochu 2003). This process is proximodistally extended, wedge shaped in anterior view, and its lateromedial width is subequal to the width of the femoral shaft. The anterior trochanter would have been the place for insertion of the m. iliotrochantericus caudalis (Hutchinson 2001b, Carrano and Hutchinson 2002, Lacerda et al. 2024). No intermuscular lines are present on the femoral shaft, contrasting with non-neotheropod and some non-tetanuran theropods (e.g. Eodromaeus murphi Martinez et al., 2011: Martinez et al. 2011; Sarcosaurus woodi: NHMUK PV R4840). No trochanteric shelf is present.
In lateromedial view, the fourth trochanter extends proximodistally on the posterior surface of the femur and is crescent shaped. It is proportionally more expanded posteriorly than in non-tetanuran (e.g. Berberosaurus liassicus: Allain et al. 2007; Carnotaurus sastrei: MACN-Pv-CH 894; Eoabelisaurus mefi: MPEF-PV 3990; Megapnosaurus rhodesiensis: Raath 1977; Sarcosaurus woodi: Ezcurra et al. 2021) and coelurosaurian theropods (e.g. Tyrannosaurus rex: Brochu 2003; Unenlagia comahuensis Novas & Puerta, 1997: Novas et al. 2021; Velociraptor mongoliensis Osborn, 1924: Norell and Makovicky 1999), similar to the condition in Allosaurus fragilis (MACN-Pv18453a), Megalosaurus bucklandii (Benson 2010), and Sinraptor dongi (Currie and Zhao 1993). The fourth trochanter is positioned more distally than the anterior trochanter. Its distal margin approaches the centre of the shaft, and its proximal margin is oriented medially. This process was probably the place of insertion of the m. caudofemoralis brevis (Hutchinson 2001b, Carrano and Hutchinson 2002, Lacerda et al. 2024). Proximally to the fourth trochanter, the surface of the bone is raised and has striations that are probably associated with the insertion of m. ischiotrochantericus (Hutchinson 2001b, Carrano and Hutchinson 2002, Lacerda et al. 2024).
In the distal end, both tibial and fibular condyles (= medial and lateral condyles, respectively) extend distally and posteriorly. The tibial condyle is more developed anteroposteriorly and ovoid than the fibular one in distal view. The fibular condyle is less distally projected, has a subcircular profile in distal view, and bears the tibiofibular crest, which extends posteriorly, as is usual in theropods (e.g. Allosaurus fragilis: MACN-Pv18453a; Asfaltovenator vialidadi: MPEF-PV 3440; Carnotaurus sastrei: MACN-Pv-CH 894; Dilophosaurus wetherilli: Marsh and Rowe 2020; Megalosaurus bucklandii: Benson 2010; Unenlagia comahuensis: Novas et al. 2021; Tyrannosaurus rex: Brochu 2003). The popliteal fossa is U-shaped in distal view and separates both condyles as a proximodistally extended depression on the posterior surface of the distal end. This fossa is not disrupted by an infrapopliteal ridge, as in most tetanuran theropods (e.g. Allosaurus fragilis: MACN-Pv18453a; Condorraptor currumili: MPEF-PV 1690–1691; Eustreptospondylus oxoniensis: Sadleir et al. 2008; Megalosaurus bucklandii: Benson 2010), in contrast to many non-tetanurans, in which this ridge is present (e.g. Ceratosaurus dentisulcatus: Madsen and Welles 2000; Megapnosaurus rhodesiensis: Raath 1977; ‘ Syntarsus ’ kayentakatae Rowe, 1989: Rowe 1989). On the anterior surface of the distal end there is an extensor fossa developed as a shallow, proximodistally extended depression, which separates both condyles from each other, as in most early averostran theropods (e.g. Allosaurus fragilis: MACN-Pv18453a; Ceratosaurus dentisulcatus: Madsen and Welles 2000; Condorraptor currumili: MPEF-PV 1690–1691; Megalosaurus bucklandii: Benson 2010; Sinraptor dongi: Currie and Zhao 1993). In contrast, this depression is absent in Cryolophosaurus ellioti (Smith et al. 2007), Herrerasaurus ischigualastensis (PVL 2566), Liliensternus liliensterni (HMN BM R 2175), and Sarcosaurus woodi (Ezcurra et al. 2021), although is present in Dilophosaurus wetherilli (Marsh and Rowe 2020) and Megapnosaurus rhodesiensis (Raath 1977). As in most theropods (e.g. Asfaltovenator vialidadi: MPEF-PV 3440; Carnotaurus sastrei: MACN-Pv-CH 894; Ceratosaurus dentisulcatus: Madsen andWelles 2000; Condorraptorcurrumili: MPEF-PV 1690–1691; Dilophosaurus wetherilli: Marsh and Rowe 2020; Sarcosaurus woodi: Ezcurra et al. 2021; Sinraptor dongi: Currie and Zhao 1993; Tyrannosaurus rex: Brochu 2003), the mediodistal crest extends proximally from the medial surface of the tibial condyle to the anteromedial edge of the distal portion of the femoral shaft.
Tibia: Both tibiae are preserved in the holotype (PVL 4073: Fig. 12), and the left tibia is preserved in the referred specimen (MACN-Pv-CH 895: Fig. 11). The tibia is slightly shorter than the femur in both specimens (0.9 ratio). The main axis of the proximal end is twisted ~50° with respect to the main axis of the distal end. The shaft is slightly curved anteriorly, as in most theropods (e.g. Allosaurus fragilis: Madsen 1976a; Ceratosaurus dentisulcatus: Madsen and Welles 2000; Dilophosaurus wetherilli: Marsh and Rowe 2020; Giganotosaurus carolini: MUCPv-CH-1; Megalosaurus bucklandii: Benson 2010; Tyrannosaurus rex: Brochu 2003). In proximal view, the bone has the typical subtriangular profile present in other early theropods, but this contour is more rounded in non-neotheropod saurischians (e.g. Herrerasaurus ischigualastensis: PVL 2566; Tawa hallae: AMNH 30886). The proximal surface is rugose and relatively flat, but the area between the lateral condyle and the lateral fossa (= incisura tibialis) is concave. The proximal medial and lateral condyles are subequal in size and posteriorly projected. These condyles are separated from each other by a deep notch, resembling the condition in most tetanuran theropods (e.g. Allosaurus fragilis: MACN-Pv18453a; Asfaltovenator vialidadi: MPEF-PV 3440; Megalosaurus bucklandii: Benson 2010; Sinraptor dongi: Currie and Zhao 1993; Tyrannosaurus rex: Brochu 2003) and noasaurids (e.g. Elaphrosaurus bambergi: Rauhut and Carrano 2016; Masiakasaurus knopfleri: Carrano et al. 2002). In contrast, non-averostran saurischians (e.g. Eodromaeus murphi: PVSJ 562; Herrerasaurus ischigualastensis: PVL 2566; Tawa hallae: AMNH 30886) and non-noasaurid ceratosaurians (e.g. Aucasaurus garridoi Coria et al., 2002: MCF-PVPH 236; Carnotaurus sastrei: MACN-Pv-CH 894; Ceratosaurus dentisulcatus: Madsen and Welles 2000; Eoabelisaurus mefi: MPEF-PV 3990) have a shallower notch or it is absent. In posterior view, the medial condyle is subquadrangular, whereas the lateral condyle is more rounded. In the same view, the medial condyle is transversely wider and more proximally projected than the lateral one. The cnemial crest is present on the anterior region of the proximal end, and it is more extended than that in non-neotheropods (e.g. Herrerasaurus ischigualastensis: PVL 2566; Tawa hallae: AMNH 30886), but less than in ceratosaurians (e.g. Ceratosaurus dentisulcatus: Madsen and Welles 2000; Eoabelisaurus mefi: MPEF-PV 3990; Majungasaurus crenatissimus: Carrano 2007; Masiakasaurus knopfleri: Carrano et al. 2002). The medial edge of the proximal end is continuous in proximal view, while the lateral side is interrupted by a lateral fossa between the cnemial crest and the lateral condyle. The cnemial crest is subrectangular in lateral view, and a small shallow, proximodistally oriented groove is present anteriorly on the lateral surface of the crest (= knee/distal extensor groove). This depression is delimited anterodistally by an oval mound-like prominence and posteriorly by the lateral ridge, which is proximodistally oriented and limits anteriorly the lateral fossa. The area of insertion of the m. femorotibialis and m. iliotibialis probably occurred between the anterior mound-like prominence, the lateral ridge, and the top of the cnemial crest (Carrano and Hutchinson 2002, Smith 2021, Lacerda et al. 2024). The lateral ridge is present in most neotheropods (e.g. Allosaurus fragilis: MACN-Pv18453a; Asfaltovenator vialidadi: MPEF-PV 3440; Ceratosaurus dentisulcatus: Madsen and Welles 2000; Cryolophosaurus ellioti: Smith et al. 2007; Eoabelisaurus mefi: MPEF-PV 3990; Giganotosaurus carolini: MUCPv-CH-1; Liliensternus liliensterni: HMN BM R 2175; Megalosaurus bucklandii: Benson 2010; Powellvenator podocitus Ezcurra, 2017: Ezcurra 2017; Tachiraptor admirabilis: Langer et al. 2014), but it is absent in non-neotheropod saurischians (e.g. Herrerasaurus ischigualastensis: PVL 2566; Tawa hallae: AMNH 30886). The lateral fossa is anteroposteriorly broad and extends distally along most of the height of the cnemial crest. The m. tibialis anterior might have originated from the striated anterior region of this fossa (Carrano and Hutchinson 2002, Smith 2021), which is limited posteriorly by a proximodistally extended tubercle positioned anteriorly to the lateral condyle. Distally from this tubercle is the fibular flange, which extends proximodistally as a well-developed crest, as occurs in other neotheropods (e.g. Allosaurus fragilis: Madsen 1976a; Condorraptor currumili: MPEF-PV 1672; Dilophosaurus wetherilli: Marsh and Rowe 2020; Megalosaurus bucklandii: Benson 2010; Megapnosaurus rhodesiensis: Raath 1977; Sinraptor dongi: Currie and Zhao 1993; Tyrannosaurus rex: Brochu 2003). In contrast, the fibular flange, at least with a development as a distinctly raised crest, is absent in non-neotheropod saurischians (e.g. Eodromaeus murphi: PVSJ 562; Herrerasaurus ischigualastensis: PVL 2566; Tawa hallae: AMNH 30886). The fibular flange is bulbous in lateral view and restricted to the proximal third of the bone. The proximalmost end of the fibular flange is anteriorly curved and does not contact the lateral condyle of the proximal end, contrasting with non-tetanuran neotheropods (Rauhut 2003).
Two processes are present in the distal end: the anteromedial process and the posterolateral process. Both have their maximum expansion at the distal margin of the bone. The posterolateral process is narrower and more extended than the anteromedial process. In distal view, the tibia is subtriangular, as is usual in averostrans (e.g. Allosaurus fragilis: Madsen 1976a; Eustreptospondylus oxoniensis: Sadleir et al. 2008; Koleken inakayali: Pol et al. 2024; Megalosaurus bucklandii: Benson 2010; Sinraptor dongi: Currie and Zhao 1993), but differs from the subquadrangular/subrectangular distal end of non-averostran theropods (e.g. Coelophysis bauri, Dilophosaurus wetherilli, and Zupaysaurus rougieri: Ezcurra et al. 2023). The facet for reception of the ascending process of the astragalus extends as a proximolaterally-to-distomedially oriented ridge, as is usual in dinosauromorphs (Novas 1996). This facet is anteroposteriorly reduced and highly angled, indicating the presence of a relatively high and laminar ascending process of the astragalus, as occurs in averostran theropods (Rauhut 2003, Ezcurra 2017). In distal view, a deep ovoid depression is present on the posteromedial corner of the distal end, which should have received a dorsal process on the astragalus. This depression resembles the condition in averostrans (e.g. Allosaurus fragilis: MACN-Pv18453a; Ceratosaurus dentisulcatus: Madsen and Welles 2000; Eustreptospondylus oxoniensis: Sadleir et al. 2008; Megalosaurus bucklandii: Benson 2010; Sinraptor dongi: Currie and Zhao 1993). In contrast, this depression is considerably deeper in some early neotheropods (e.g. Zupaysaurus rougieri: Ezcurra and Novas 2007), but shallower in Eodromaeus murphi (PVSJ 562), Lepidus praecisio Nesbitt & Ezcurra, 2015 (Nesbitt and Ezcurra 2015), Megapnosaurus rhodesiensis (Raath 1977), and Tachiraptor admirabilis (Langer et al. 2014). A longitudinal ridge is absent in the distal end, in contrast to many non-tetanuran theropods (e.g. Camposaurus arizonensis Hunt et al., 1998: Ezcurra and Brusatte 2011; Ceratosaurus dentisulcatus: Madsen and Welles 2000; Dilophosaurus wetherilli: Marsh and Rowe 2020). Despite the fact that it depends on the ontogenetic stage (Tykoski 2005, Griffin 2018), the tibia is not fused to the astragalus, resembling the condition in early tetanurans (e.g. Allosaurus fragilis: Madsen 1976a; Megalosaurus bucklandii: Benson 2010; Sinraptor dongi: Currie and Zhao 1993). They are commonly fused in skeletally mature specimens of non-tetanuran neotheropods (e.g. Camposaurus arizonensis: Ezcurra and Brusatte 2011; Ceratosaurus dentisulcatus: Madsen and Welles 2000; Eoabelisaurus mefi: MPEF-PV 3990; Masiakasaurus knopfleri: Carrano et al. 2002; Megapnosaurus rhodesiensis: Raath 1977) and deeply nested coelurosaurs (Gauthier 1986).
Fibula: Both fibulae are preserved in the holotype (PVL 4073: Fig. 13), and the distal end of a right fibula is preserved in the referred specimen (MACN-Pv-CH 895: Fig. 14). The fibula is long and slender, considerably less robust than the tibia. The proximal end is expanded anteroposteriorly, but more extended posteriorly, and has the typical subtriangular profile of neotheropods in lateral view (e.g. Allosaurus fragilis: Madsen 1976a; Ceratosaurus dentisulcatus: Madsen and Welles 2000; Dilophosaurus wetherilli: Marsh and Rowe 2020; Eoabelisaurus mefi: MPEF-PV 3990; Majungasaurus crenatissimus: Carrano 2007; Megapnosaurus rhodesiensis: Raath 1977; Sinraptor dongi: Currie and Zhao 1993). In contrast, the proximal end is more symmetric in lateral view in herrerasaurids (e.g. Herrerasaurus ischigualastensis: Novas 1993; Staurikosaurus pricei Colbert, 1970: Bittencourt and Kellner 2009) and other non-neotheropod saurischians (e.g. Eodromaeus murphi: PVSJ 562; Tawa hallae: AMNH 30886). In proximal view, the bone is comma shaped, being concave medially, and the anterior region is thicker and more rounded than the posterior one, resembling the condition in most neotheropods (e.g. Allosaurus fragilis: Madsen 1976a; Asfaltovenator vialidadi: MPEF-PV 3440; Ceratosaurus dentisulcatus: Madsen and Welles 2000; Dilophosaurus wetherilli: Marsh and Rowe 2020; Liliensternus liliensterni: HMN BM R 2175; Megapnosaurus rhodesiensis: Raath 1977). The medial fossa originates as an extensive depression close to the proximal margin on the medial face. The fossa of Piatnitzkysaurus floresi is shallower than in several averostrans (e.g. Allosaurus fragilis: MACNPv18453a; Ceratosaurus dentisulcatus: Madsen and Welles 2000; Eoabelisaurusmefi: MPEF-PV3990; Majungasauruscrenatissimus: Carrano 2007), deeper than in Eodromaeus murphi (PVSJ 562), Herrerasaurus ischigualastensis (Novas 1993), and Tawa hallae (AMNH 30886), and similar to the condition in Dilophosaurus wetherilli (Marsh and Rowe 2020) and Liliensternus liliensterni (HMN BM R 2175). The fibular sulcus extends distally from the medial fossa and along most of the bone, becoming shallower distally. On the anterior margin of the medial fossa there is a thickening of the edge as a medially oriented ridge, which probably represents the attachment of the m. popliteus (Carrano and Hutchinson 2002). Proximally to this ridge there is an ovoid depression. A narrow proximodistally oriented ridge is present on the anterior region of the lateral surface in the proximal end. The fibular shaft is mostly straight, but it curves posteriorly around the transition with the proximal end. A proximodistally oriented, low and thick ridge (= anterolateral process) occurs distal to the level of this curvature and probably represents the attachment of the m. iliofibularis (Hutchinson 2001a, Carrano and Hutchinson 2002, Lacerda et al. 2024). This ridge is also low in early saurischians, coelophysoids, and non-ceratosaurian averostran-line neotheropods (e.g. Allosaurus fragilis: Madsen 1976a; Eodromaeus murphi: PVSJ 562; Eustreptospondylus oxoniensis: Sadleir et al. 2008; Herrerasaurus ischigualastensis: Novas 1993; Megapnosaurus rhodesiensis: Raath 1977; Sinraptor dongi: Currie and Zhao 1993; Staurikosaurus pricei: Bittencourt and Kellner 2009; Tawa hallae: AMNH 30886), but it is more developed in ceratosaurians (e.g. Berberosaurus liassicus: Allain et al. 2007; Ceratosaurus dentisulcatus: Madsen and Welles 2000; Eoabelisaurusmefi: MPEF-PV3990; Majungasauruscrenatissimus: Carrano 2007). The fibular shaft tapers distally until the distal end, which expands slightly anteroposteriorly. In distal view, the bone is ovoid and the surface rugose. There is a short anterior ridge on the lateral face of the distal end. The transverse section of the bone is U-shaped as a consequence of the medial sulcus, but it becomes D-shaped closer to the distal end.
Distal tarsals 3 and 4 Distal tarsals 3 and 4 are preserved in the referred specimen (MACN-Pv-CH 895: Fig. 14). The presence of these two distal tarsals is usual in theropods (Madsen 1976a, Currie and Zhao 1993, Rauhut et al. 2018, Marsh and Rowe 2020), and both are subequal in size, as in Dilophosaurus wetherilli (Marsh and Rowe 2020) and Sinraptor dongi (Currie and Zhao 1993). The distal tarsal 3 is narrow anterolateraly and broad posteromedially, although it is thinner proximodistally than the distal tarsal 4, and both have a similar anteroposterior length in proximodistal view. Both bones are not fused to each other, contrasting with skeletally mature specimens of coelophysoids (e.g. Megapnosaurus rhodesiensis: Raath 1977; Panguraptor lufengensis You et al., 2014: You et al. 2014; Powellvenator podocitus: Ezcurra 2017; ‘ Syntarsus ’ kayentakatae: Rowe 1989).
The distal tarsal 3 has a rhomboid profile in proximal view and a convex anteromedial margin, which becomes slightly concave towards the posteromedial corner, resembling the condition in some allosauroids (e.g. Allosaurus fragilis: Madsen 1976a; Sinraptor dongi: Currie and Zhao 1993). In contrast, the anteromedial margin is concave and becomes flatter towards the posteromedial corner in Megapnosaurus rhodesiensis (Raath 1977), the medial margin is convex in Powellvenator podocitus (Ezcurra 2017), and this margin is straight anteriorly and concave posteriorly in the ‘Padian theropod’ (PEFO 21373/UCMP 129618) and Dilophosaurus wetherilli (Marsh and Rowe 2020). Distal tarsal 3 has a posterolateral process, as in the ‘Padian theropod’ (PEFO 21373/UCMP 129618) and Sinraptor dongi (Currie and Zhao 1993), but this process is absent in Pandoravenator fernandezorum Rauhut & Pol, 2017 (Rauhut and Pol 2017). The proximal surface is convex, whereas the distal one is concave anteriorly and posteromedially for articulation with the metatarsal III. The distal tarsal 3 covers two-thirds of the proximal surface of the metatarsal III, as in the coelophysoids Megapnosaurus rhodesiensis (Raath 1977) and Powellvenator podocitus (Ezcurra 2017).
The distal tarsal 4 has a pointed anteromedial corner and a more rounded and slightly proximally raised anterolateral side, similar to the condition in Allosaurus fragilis (Madsen 1976a), Dilophosaurus wetherilli (Marsh and Rowe 2020), Pandoravenator fernandezorum (MPEF-PV 1773-9), and Sinraptor dongi (Currie and Zhao 1993). The anterior margin of the distal tarsal 4 is straight, as in Megapnosaurus rhodesiensis (Raath 1977), whereas it is convex in Dilophosaurus wetherilli (Marsh and Rowe 2020), Dracoraptor hanigani (Martill et al. 2016), and Powellvenator podocitus (Ezcurra 2017). The posterior margin of the distal tarsal 4 is also straight, as in Allosaurus fragilis (Madsen 1976a), Dilophosaurus wetherilli (Marsh and Rowe 2020), and Megapnosaurus rhodesiensis (Raath 1977), although in the last three species this margin is narrower lateromedially. The proximodistal thickness is greater on the anteromedial side than on the anterolateral one, while the posterolateral side is thicker than the posteromedial one. The proximal surface is relatively flat, whereas the distal surface is interrupted by a transverse groove around the anteroposterior mid-depth of the bone for articulation with the metatarsal IV. The distal tarsal 4 articulates on a concave margin on the medial margin of the distal tarsal 3, in contrast to Pandoravenator fernandezorum (MPEF-PV 1773- 9), in which this concave margin is absent and the distal tarsal 4 covers the metatarsal IV almost completely, as in Megapnosaurus rhodesiensis (Raath 1977). The posterolateral region of this bone has a notch in proximal view, resembling the condition in Ceratosaurus dentisulcatus (Madsen and Welles 2000), Dilophosaurus wetherilli (Marsh and Rowe 2020), Megapnosaurus rhodesiensis (Raath 1977), and Powellvenator podocitus (Ezcurra 2017). This notch is usually absent in non-neotheropod saurischians, such as Herrerasaurus ischigualastensis (Novas 1993) and Saturnalia tupinquim Langer et al., 1999 (Langer 2003).
Metatarsus: The left metatarsals II–IV are preserved in the referred specimen (MACN-Pv-CH 895: Fig. 15), while metatarsals I and V are unknown in Piatnitzkysaurus floresi. Metatarsals II and IV are relatively similar in length, and both are shorter than metatarsal III, which is the longest and also that with the narrowest shaft. Metatarsal III as the longest autopodium is a usual condition among theropods. Although metatarsals II and IV are similar, the former is slightly more robust and straighter, whereas metatarsal IV curves laterally in anteroposterior view. The metatarsus is less robust than in the megalosauroids Megalosaurus bucklandii (Benson 2010) and Torvosaurus tanneri (Britt 1991), resembling the condition of the ceratosaurians Ceratosaurus nasicornis (Gilmore 1920) and Majungasaurus crenatissimus (Carrano 2007), the allosauroids Allosaurus fragilis (Madsen 1976a) and Sinraptor dongi (Currie and Zhao 1993), and the non-averostrans Dilophosaurus wetherilli (Marsh and Rowe 2020) and Herrerasaurus ischigualastensis (PVL 2566). In contrast, in coelophysoids (e.g. Megapnosaurus rhodesiensis: Raath 1977; ‘ Syntarsus ’ kayentakatae: Rowe 1989), Sarcosaurus woodi (Ezcurra et al. 2021), some noasaurids (e.g. Elaphrosaurus bambergi: Rauhut and Carrano 2016; Limusaurus inextricabilis: Xu et al. 2009; Masiakasaurus knopfleri: Sampson et al. 2001), and Tawa hallae (Nesbitt et al. 2009) the metatarsus is considerably more gracile. Proximally, metatarsal III articulates with the distal tarsal 3, and metatarsal IV articulates with the distal tarsal 4. In the case of metatarsal III, it articulates via a flat surface that is slightly depressed posteriorly, whereas metatarsal IV has an elevated surface on the centre of the proximal surface that fits in a complementary shallow depression on distal tarsal 4. There is no sign of fusion between metatarsals, in contrast to some coelophysoids (e.g. Megapnosaurus rhodesiensis: Raath 1977; Powellvenator podocitus: PVL 4414-1; ‘ Syntarsus ’ kayentakatae: Rowe 1989), and Ceratosaurus nasicornis (Gilmore 1920).
Deformation in the curvature of the shaft is observed in metatarsals III and IV. The fossil record of bone deformations that occurred during life is scarce among non-avian dinosaurs (e.g. Tanke and Rothschild 2014, Senter and Sullivan 2019, Xing et al. 2024), although in this case, especially the deformation in the metatarsal III seems to be the result of diagenetic processes. This assumption is based on the fact that, when aligning the proximal ends of the three left metatarsals, their shafts are either superimposed or articulated in such a way that the animal would not even have been able to step on it.
Metatarsal II: Metatarsal II is elongated and expanded at both proximal and distal ends, as in metatarsals III and IV, which is the usual condition in theropods (e.g. Allosaurus fragilis: Madsen 1976a; Ceratosaurus nasicornis: Gilmore 1920; Dilophosaurus wetherilli: Marsh and Rowe 2020; Majungasaurus crenatissimus: Carrano 2007; Megalosaurus bucklandii: Benson 2010; Tyrannosaurus rex: Brochu 2003). In proximal view, it has a trapezoidal shape, as in allosauroids (e.g. Allosaurus fragilis: Madsen 1976a; Sinraptor dongi: Currie and Zhao 1993) and some megalosauroids (e.g. Eustreptospondylus oxoniensis: Sadleir et al. 2008; Megalosaurus bucklandii: Benson 2010), but contrasting with herrerasaurids (much more expanded anteroposteriorly; e.g. Herrerasaurus ischigualastensis: PVL 2566; Sanjuansaurus gordilloi Alcober & Martinez, 2010: Alcober and Martinez 2010), abelisauroids (subtriangular or D-shaped; e.g. Elaphrosaurus bambergi: Rauhut and Carrano 2016; Eoabelisaurus mefi: MPEF-PV 3990; Masiakasaurus knopfleri: Sampson et al. 2001; Saltriovenator zanellai Dal Sasso et al., 2018: Dal Sasso et al. 2018), and Pandoravenator fernandezorum (subtriangular: MPEF-PV 1773). It is also trapezoidal, but slightly transversely narrower, in coelophysoids (e.g. Megapnosaurus rhodesiensis: Raath 1977; Powellvenator podocitus: PVL 4414-1) and Dilophosaurus wetherilli (Marsh and Rowe 2020). The postermedial edge of the proximal end is sharper and more extended than the anterior one. There is a shallow depression on the anterior surface of this end, as in Allosaurus fragilis (Madsen 1976a) and Sinraptor dongi (Currie and Zhao 1993). The longer lateral margin of the proximal end contacts metatarsal III, and there is a flat surface with striations on the proximal third of the lateral surface that indicates the contact zone between both metatarsals. The medial surface of the proximal end is rounded along the shaft. In lateromedial view, the bone tapers from the proximal end to the shaft of the bone. The posteromedial margin of the proximal end has a concave notch in proximal view, as in many tetanuran theropods (e.g. Allosaurus fragilis: Madsen 1976a; Eustreptospondylus oxoniensis: Sadleir et al. 2008; Megalosaurus bucklandii: Benson 2010; Sinraptor dongi: Currie and Zhao 1993; Tyrannosaurus rex: Brochu 2003) and some ceratosaurians (e.g. Ceratosaurus nasicornis: Gilmore 1920; Majungasaurus crenatissimus: Carrano 2007), contrasting with most non-averostran theropods, in which this concave margin is absent or shallower (e.g. Dilophosaurus wetherilli: Marsh and Rowe 2020; Liliensternus liliensterni: HMN BM R 2175; Megapnosaurus rhodesiensis: Raath 1977; Powellvenator podocitus: PVL 4414-1). The metatarsal II has a relatively straight shaft, as in coelophysoids (e.g. Megapnosaurus rhodesiensis: Raath 1977), Sarcosaurus woodi (Ezcurra et al. 2021), herrerasaurids (e.g. Herrerasaurus ischigualastensis: PVL 2566; Sanjuansaurus gordilloi: Alcober and Martinez 2010), megalosauroids (e.g. Megalosaurus bucklandii: Benson 2010; Torvosaurus tanneri: Britt 1991), and the abelisauroids Majungasaurus crenatissimus (Carrano 2007) and Masiakasaurus knopfleri (Sampson et al. 2001). In contrast, this condition differs from the curved shaft of Ceratosaurus nasicornis (Gilmore 1920), Dilophosaurus wetherilli (Marsh and Rowe 2020), and the allosauroids Allosaurus fragilis (Madsen 1976a) and Sinraptor dongi (Currie and Zhao 1993). In anteroposterior view, the distal end widens from the shaft and is rounded. On both lateral and medial sides of the distal end, there is a distinct rounded fossa (i.e. ligament pit), which is larger on the lateral side. In distal view, the medial margin is straight, whereas the lateral margin is more developed, obliquely oriented. The lateral condyle is larger, rounded, and tapers posterolaterally, whereas the medial condyle is shorter. An oblique depression occurs at the distal margin, on the posterior region of the distal end, and proximally reaches the shaft. This depression slopes laterally towards proximal and becomes shallower. A low ridge arises on the medial edge of this depression on the shaft.
Metatarsal III: Metatarsal III is an elongated bone, lateromedially compressed in the proximal end. The main axis of this end is twisted ~60° with respect to the transverse axis of the distal end, although this condition is probably as a result of diagenetic processes. In proximal view, the bone is hourglass shaped, as is usual in tetanuran theropods (e.g. Allosaurus fragilis: Madsen 1976a; Eustreptospondylus oxoniensis: Sadleir et al. 2008; Megalosaurus bucklandii: Benson 2010; Sinraptor dongi: Currie and Zhao 1993; Torvosaurus tanneri: Britt 1991), in contrast to the T-shaped or subrectangular profile of non-tetanuran theropods (e.g. Ceratosaurus nasicornis: Gilmore 1920; Dilophosaurus wetherilli: Marsh and Rowe 2020; Elaphrosaurus bambergi: Rauhut and Carrano 2016; Eoabelisaurus mefi: MPEF-PV 3990; Megapnosaurus rhodesiensis: Raath 1977; Saltriovenator zanellai: Del Sasso et al. 2018). The medial margin of the proximal end is relatively straight, and the medial surface below this margin is flat for the articulation with the metatarsal II. The lateral margin is slightly concave, increasing the curvature towards the posteromedial region until a wedge-shaped expansion posteromedially, resembling the condition in allosauroids (e.g. Allosaurus fragilis: Madsen 1976a; Sinraptor dongi: Currie and Zhao 1993) and megalosauroids (e.g. Eustreptospondylus oxoniensis: Sadleir et al. 2008; Torvosaurus tanneri: Britt 1991). This expansion continues on the lateral surface, whereas the posterolateral region has a flat surface, slightly sunken, where it articulates with metatarsal IV. The anterolateral region of the proximal end is more expanded than the posteromedial one and has a sharp anterior vertical margin where the flat surface of the medial surface ends. In contrast, the posteromedial end is wider in coelophysoids and ceratosaurians (e.g. Ceratosaurus nasicornis: Gilmore 1920; Elaphrosaurus bambergi: Rauhut and Carrano 2016; Megapnosaurus rhodesiensis: Raath 1977). The shaft of the bone has a concave curvature medially, resembling the condition in Dilophosaurus wetherilli (Marsh and Rowe 2020) and, less conspicuously, in Allosaurus fragilis (Madsen 1976a) and Sinraptor dongi (Currie and Zhao 1993), although it could be a consequence of diagenetic processes in Piatnitzkysaurus floresi. The transverse section of the shaft is oval proximally, and it becomes subtriangular/trapezoidal distally because of the thickening and elevation of the posterolateral margin as a ridge. On the posterolateral side of the shaft there is an oval, oblique depression close to the proximal end. The distal section of the shaft is broken, and a posterior section is missing. The distal end expands lateromedially and is subrectangular in distal view. Both the lateral and medial surfaces of this end have an oval, relatively deep ligament pit surrounded by thickened margins, which give a semicircular profile to the distal margin of the bone in lateromedial view. The distal articular surface is distinguishable by a slightly thickened edge of bone. This thickening extends on the anterior surface of the distal end up to the height of the centre of the ligament pits, and on the posterior surface up to the height of the distal edge of the ligament pits. In anterior view, the thickened edge of the articular surface is proximally convex. The posterior surface of the distal end has a shallow depression, which is seen as a shallowly concave margin in distal view. On the anterior surface of the distal end there is an extensor fossa proximal to the articular surface.
Metatarsal IV: Metatarsal IV is elongated, relatively slender, and lateromedially expanded at the proximal end. In proximal view, the bone has a rounded lateral half and a tongue-like posteromedial process in the medial side, resembling the condition in allosauroids (e.g. Allosaurus fragilis: Madsen 1976a; Sinraptor dongi: Currie and Zhao 1993) and Condorraptor currumili (MPEF-PV 1692), but this process is absent in megalosauroids (e.g. Megalosaurus bucklandii: Benson 2010; Torvosaurus tanneri: Britt 1991). Anteriorly to this process there is a transverse broad concavity for the reception of metatarsal III, as in tetanuran theropods (e.g. Allosaurus fragilis: Madsen 1976a; Asfaltovenator vialidadi: MPEF-PV 3440; Condorraptor currumili: MPEF-PV 1692; Megalosaurus bucklandii: Benson 2010; Sinraptor dongi: Currie and Zhao 1993). In contrast, this facet is flat, and the profile of the proximal end is oval or subtriangular in most non-tetanuran neotheropods (e.g. Dilophosaurus wetherilli: Marsh and Rowe 2020; Ceratosaurus nasicornis: Gilmore 1920; Elaphrosaurus bambergi: Rauhut and Carrano 2016; Eoabelisaurus mefi: MPEF-PV 3990; Liliensternus liliensterni: HMN BM R 2175; Majungasaurus crenatissimus: Carrano 2007; Megapnosaurus rhodesiensis: Raath 1977) and Chilesaurus diegosuarezi (Novas et al. 2015), whereas it is subrectangular in non-neotheropod saurischians (e.g. Herrerasaurus ischigualastensis: PVL 2566; Tawa hallae: Nesbitt et al. 2009). The posterior surface of the proximal end is flat and has a small, proximodistally oriented ridge close to the posterolateral margin, which is a similar condition to that in Condorraptor currumili (MPEF-PV 1692). The shaft of the bone is laterally concave curved, as in Condorraptor currumili (MPEF-PV 1692), Dilophosaurus wetherilli (Marsh and Rowe 2020), allosauroids (e.g. Allosaurus fragilis: Madsen 1976a; Sinraptor dongi: Currie and Zhao 1993), and some ceratosaurians (e.g. Ceratosaurus nasicornis: Gilmore 1920; Majungasaurus crenatissimus: Carrano 2007; Masiakasaurus knopfleri: Sampson et al. 2001), whereas it is less curved to straight in coelophysoids (e.g. Megapnosaurus rhodesiensis: Raath 1977; ‘ Syntarsus ’ kayentakatae: Rowe 1989) and some megalosauroids (e.g. Megalosaurus bucklandii: Benson 2010; Torvosaurus tanneri: Britt 1991). The transverse section of the shaft is suboval, with a relatively flattened posterior margin, resembling the condition in most theropods (e.g. Ceratosaurus nasicornis: Gilmore 1920; Condorraptor currumili: MPEF-PV 1692; Majungasaurus crenatissimus: Carrano 2007; Megalosaurus bucklandii: Benson 2010; Sinraptor dongi: Currie and Zhao1993). The distal half of the posterior surface of the shaft has a distinct, proximodistally oriented scar for the probable attachment of the m. gastrocnemius (Carrano and Hutchinson 2002). The shaft thickens as a ridge medially, and this ridge is continuous with the edge of the gastrocnemius scar. This scar is more developed than in non-averostran theropods (e.g. Dilophosaurus wetherilli: Marsh and Rowe 2020; Megapnosaurus rhodesiensis: Raath 1977; Sarcosaurus woodi: Ezcurra et al. 2021), resembling the condition in most early averostrans (e.g. Aucasaurus garridoi: MCF-PVPH 236; Condorraptor currumili: MPEF-PV 1692; Majungasaurus crenatissimus: Carrano 2007; Sinraptor dongi: Currie and Zhao 1993; Tyrannosaurus rex: Brochu 2003), but it is also present in several non-theropod dinosaurs, and it is absent in birds (a prominent hypotarsus is present proximally in this group for the attachment of m. gastrocnemius; Dilkes 2000, Carrano and Hutchinson 2002). The distal end of the metatarsal IV is slightly anteroposteriorly expanded and is subtriangular in distal view, which is a similar condition to that in Ceratosaurus nasicornis (Gilmore 1920), Condorraptor currumili (MPEF-PV 1692), and Sinraptor dongi (Currie and Zhao 1993). In contrast, the distal end is sub-quadrangular in Dilophosaurus wetherilli (Marsh and Rowe 2020), Herrerasaurus ischigualastensis (PVL 2566), and Tawa hallae (Nesbitt et al. 2009), being broader lateromedially. The distal surface has some grooves on the medial edge and has two flanges on the posterolateral and posteromedial sides of the end, respectively, which are separated from each other by a shallow depression. The lateral flange is broken but appears to be narrower than the medial flange. The distal surface extends posteriorly up to the flanges and continuous anteriorly up to the middle half of the end. The medial side of the distal end is flat, barely depressed, whereas the lateral side is smooth and slightly convex. A shallow ligament pit is present only on the medial side. An extensor fossa on the anterior surface of the distal end is absent.
Phalanx: The distal end of a phalanx is preserved in the referred specimen (MACN-Pv-CH 895: Fig. 16). It is not possible to determine whether it is left or right, or whether it belongs to the manus or pes, although possibly it is the manual phalanx II-2. This phalanx resembles the general morphology of the phalanx II-2 of Allosaurus fragilis (cast of USNM 4734) and Asfaltovenator vialidadi (MPEF-PV 3440), in contrast to the shorter phalanges of ceratosaurians (e.g. Ceratosaurus nasicornis: Gilmore 1920; Eoabelisaurus mefi: MPEF-PV 3390). It is relatively symmetric, as is usual in central phalanges (i.e. manual digit II of tetanurans), and it finishes distally into two rounded condyles, which are separated by a dorsoventrally oriented groove, as in Allosaurus fragilis (cast of USNM 4734) and Asfaltovenator vialidadi (MPEF-PV 3440). Both condyles extend more ventrally than dorsally, and they are thicker lateromedially than in the manual or pedal phalanges of similar size of most Jurassic theropods (e.g. Allosaurus fragilis: cast of USNM 4734, Madsen 1976a; Dilophosaurus wetherilli: Marsh and Rowe 2020; Eoabelisaurus mefi: MPEF-PV 3390; Eustreptospondylus oxoniensis: Sadleir et al. 2008; Xuanhanosaurus qilixiaensis: IVPP V.6729). The bone is trapezoidal in distal view, and the transverse section of the shaft is ovoid, being dorsoventrally compressed. On both lateral and medial sides of the condyles there is an oval ligament pit. One ligament pit is shallow and positioned dorsally, as occurs in some manual phalanges of other Jurassic tetanurans (e.g. Allosaurus fragilis: cast of USNM 4734; Asfaltovenator vialidadi: MPEF-PV 3440; Xuanhanosaurus qilixiaensis: IVPP V.6729), whereas the other pit is deeper and located at the centre of the condyle. This latter ligament pit is deeper than in the manual phalanges of other Jurassic theropods (e.g. Allosaurus fragilis: cast of USNM 4734; Asfaltovenator vialidadi: MPEF-PV 3440; Dilophosaurus wetherilli: Marsh and Rowe 2020; Xuanhanosaurus qilixiaensis: IVPP V.6729).
description: Published as part of Pradelli Diego Pol, Luciano A. & Ezcurra, Martín D., 2025, The appendicular osteology of the Early Jurassic theropod Piatnitzkysaurus floresi and its implications on the morphological disparity of non-coelurosaurian tetanurans, pp. 1-40 in Zoological Journal of the Linnean Society 203 (1) on pages 4-30, DOI: 10.1093/zoolinnean/zlae176, http://zenodo.org/record/14834787