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Dinosauria (Fig. 6: node 1) Definition adopted: The least inclusive clade containing Iguanodon bernissartensis, Megalosaurus bucklandii and Cetiosaurus oxoniensis Phillips, 1871 (Langer et al., 2020). Characters in support (here): Basipterygoid process mediolaterally compressed (Char. 62: 0 → 1); post-glenoid process of the coracoid extending caudal to glenoid (Char. 140: 0 → 1); presence of a strong pillar caudal to the pre-acetabular embayment of the ilium (Char. 180: 0 → 1); pubis length more than 70% or more of femoral length (Char. 188: 0 → 1); more dorsally extensive contact between the medial surface of the ischia (Char. 197: 0 → 1); presence of a dorsolateral sulcus on the ischium (Char. 198: 0 → 1); rounded or elliptical outline of the distal portion of the ischium (Char. 199: 0 → 1); kinked transition from the femoral shaft to the femoral head (Char. 208: 0 → 1); angled ‘greater trochanter’ of the femur (Char. 216: 0 → 1); presence of a transverse groove on the proximal surface of the femur (Char. 217: 0 → 1); concave caudal margin of the distal end of the tibia (Char. 240: 0 → 1); and metatarsal IV subequal or shorter than metatarsal II (Char. 217: 0 → 1)., Published as part of Norman, David B, Baron, Matthew G, Garcia, Mauricio S & Müller, Rodrigo Temp, 2022, Taxonomic, palaeobiological and evolutionary implications of a phylogenetic hypothesis for Ornithischia (Archosauria: Dinosauria), pp. 1273-1309 in Zoological Journal of the Linnean Society 196 (4) on page 1285, DOI: 10.1093/zoolinnean/zlac062, http://zenodo.org/record/7381299, {"references":["Langer MC, Novas FE, Bittencourt JS, Ezcurra MD, Gauthier JA. 2020. Dinosauria R. Owen 1842. In:"]}

Ornithischia (Fig. 6: stem/branch 3) Definition adopted: The most inclusive clade that includes Iguanodon bernissartensis but neither Megalosaurus bucklandii nor Diplodocus carnegii (after Baron et al., 2017a). Characters in support: Horizontal or only gently arched premaxillary palate (Char. 17: 0 → 1); strongly curved and hook-shaped jugal process of the ectopterygoid (Char. 57: 0 → 1; Fig. 5E); ventrally inclined dorsal surface of the rostrum of the dentary (Char. 74: 0 → 1); retroarticular is slightly upturned at its distal end (Char. 82: 0 → 1; Fig. 7F); premaxilla with four teeth (Char. 84: 0 → 1); teeth ankylosed into the alveoli (Char. 100: 0 → 1; Fig. 7G); and medial articular facet of the proximal portion of the femur is straight in caudomedial view (Char. 213: 0 → 1; Fig. 7J).

Saurischia (Fig. 6: stem/branch 2) Definitionadopted: The most inclusive clade containing Allosaurus fragilis (Marsh, 1877) and Camarasaurus supremus Cope, 1877 but not Stegosaurus stenops Marsh, 1887 (after Langer et al., 2020). Characters in support: Subnarial foramen present (Char. 5: 0 → 1); premaxilla with a deep narial fossa at the rostroventral corner of the naris (Char. 19: 0 → 1); maxilla with significantly deeper rostrally than caudally surface ventral to the external antorbital fenestra (Char. 29: 1 → 0); caudal chonos of cranial cervical vertebrae as a shallow fossa (Char. 109: 0 → 1); epipophyses present in cervical vertebrae 6-9 (Char. 111: 0 → 1); neural arch of cervical vertebrae lower than caudal articular facet of the centrum (Char. 113: 0 → 1); articular surface of the rib of the first primordial sacral vertebra is C-shaped in lateral view (Char. 130: 0 → 1); transverse processes of sacral vertebrae roof the space between the ribs (Char. 131: 0 → 1); humerus + radius/femur + tibia length ratio less than 0.55 (Char. 141: 0 → 1); apex of deltopectoral crest between 30% and 43% down the length of the humerus (Char. 142: 0 → 1); expanded deltopectoral crest of the humerus (Char. 143: 0 → 1); humerus shorter than 0.6 of the length of the femur (Char. 145: 0 → 1); humerus sigmoid in lateral view (Char. 147: 0 → 1); average length of digits I–III of the manus more than 0.4 of the total length of humerus plus radius (Char. 153: 0 → 1); trenchant unguals on digits I–III of the manus (Char. 155: 0 → 1); deep extensor pits on distal/dorsal portion of metacarpals II-III (Char. 156: 0 → 1); width of the shaft of metacarpal IV significantly narrower than that of metacarpals I-III (Char. 167: 0 → 1); ventral margin of the acetabular wall of the ilium straight to concave (Char. 175: 0 → 1/2); distal end of the pubis slightly expanded (Char. 190: 0 → 1); kinked transition from the femoral shaft to the femoral head and expanded head (Char. 190: 1 → 2); deep groove between the lateral condyle and crista tibiofibularis on the distal end of the femur (Char. 231: 0 → 1); cnemial crest of the tibia arcs craniolaterally (Char. 234: 1 → 2); tibial articulation caudal to the ascending process of the astragalus with a markedly rimmed and elliptical fossa (Char. 249: 0 → 1); proximal articular facet for fibula of astragalus less than 0.3 of the transverse width of the bone (Char. 250: 0 → 1); cranial ascending process separated from the cranial surface of the astragalar body by a platform (Char. 256: 1 → 2); calcaneum with a concave articular surface for the fibula (Char. 261: 0 → 1); pointed caudal prong of the distal tarsal 4 (Char. 265: 0 → 1); distal tarsal 4 with a medial process (Char. 266: 0 → 1); and metatarsal IV with an expanded proximal portion (Char. 272: 0 → 1).

Thyreophora (Fig. 6: stem/branch 8) Definition adopted: The most inclusive clade that contains Ankylosaurus magniventris Brown, 1908 but not Iguanodon bernissartensis (after Sereno, 1998). Neornithischia (Fig. 6: stem/branch 9) Heterodontosauridae (Fig. 6: stem/branch 10) SYSTEMATIC PALAEONTOLOGY: PARAPREDENTATA (NOVUM) Oldest known occurrence: Lutungutali sitwensis., Published as part of Norman, David B, Baron, Matthew G, Garcia, Mauricio S & Müller, Rodrigo Temp, 2022, Taxonomic, palaeobiological and evolutionary implications of a phylogenetic hypothesis for Ornithischia (Archosauria: Dinosauria), pp. 1273-1309 in Zoological Journal of the Linnean Society 196 (4) on pages 1286-1289, DOI: 10.1093/zoolinnean/zlac062, http://zenodo.org/record/7381299, {"references":["Sereno PC. 1998. A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria. Neues Jahrbuch fur Geologie und Palaontologie Abhandlungen 109: 41 - 83.","Dzik J. 2003. A beaked herbivorous archosaur with dinosaurian affinities from the early Late Triassic of Poland. Journal of Vertebrate Paleontology 23: 556 - 574.","Barrett PM, Butler RJ, Mundil R, Scheyer TM, Irmis RB, Sanchez-Villagra MR. 2014. A palaeoequatorial ornithischian and the new constraints on early dinosaur diversification. Proceedings of the Royal Society B 281: 6.","Butler RJ, Galton PM, Porro LB, Chiappe LM, Erickson GM, Henderson DM. 2010. Lower limits of the ornithischian dinosaur body size inferred from a new Upper Jurassic heterodontosaurid from North America. Proceedings of the Royal Society B 277: 375 - 381.","Martz JW, Small BJ. 2019. Non-dinosaurian dinosauromorphs from the Chinle Formation (Upper Triassic) of the Eagle Basin, northern Colorado: Dromomeron romeri (Lagerpetidae) and a new taxon, Kwanasaurus williamparkeri (Silesauridae). PeerJ 7: e 7551.","Nesbitt SJ, Langer MC, Ezcurra MD. 2019. The anatomy of Asilisaurus kongwe, a dinosauriform from the Lifua Member of the Manda Beds (~ Middle Triassic) of Africa. Anatomical Record 303: 813 - 873.","Cooper MR. 1985. A revision of the ornithischian dinosaur Kangnasaurus coetzeei Haughton, with a classification of the Ornithischia. Annals of the South African Museum 95: 281 - 317.","Crompton AW, Charig AJ. 1962. A new ornithischian from the Upper Triassic of South Africa. Nature 196: 1074 - 1077.","Sereno PC. 2005. Stem Archosauria v. 1.0. In: Sereno PC, McAllister S, Brusatte SL. TaxonSearch: a relational database for suprageneric taxa and phylogenetic definitions. PhyloInformatics 8: 1 - 25.","Owen R. 1842. Report on British fossil reptiles. Part 2. Report of the British Association for the Advancement of Science (Plymouth) XI: 60 - 204.","Seeley HG. 1888. On the classification of the fossil animals commonly named Dinosauria. Proceedings of the Royal Society of London 43: 165 - 171.","Ferigolo J, Langer MC. 2006. A Late Triassic dinosauriform from south Brazil and the origin of the ornithischian predentary bone. Historical Biology 19: 1 - 11.","Romer AS. 1956. Osteology of the reptiles. Chicago: University of Chicago Press.","Nabavizadeh A, Weishampel DB. 2016. The predentary bone and its significance in the evolution of feeding mechanisms in ornithischian dinosaurs. The Anatomical Record 299: 1358 - 1388.","Marsh OC. 1894. The typical Ornithopoda of the American Jurassic. American Journal of Science and Arts 48: 85 - 90.","Nesbitt SJ. 2011. The early evolution of archosaurs: relationships and origin of major clades. Bulletin of the American Museum of Natural History 352: 1 - 292.","Holliday CM, Nesbitt SJ. 2013. Morphology and diversity of the mandibular symphysis of archosauriforms. Geological Society of London. Special Publication 379: 555 - 571.","You H, Dodson P. 2004. Basal Ceratopsia. In: Weishampel DB, Dodson P, Osmolska H, eds. The Dinosauria, 2 nd edn. Berkeley: University of California Press, 478 - 493.","Sereno PC. 2012. Taxonomy, morphology, masticatory function and phylogeny of heterodontosaurid dinosaurs. ZooKeys 226: 1 - 225.","Baron MG, Norman DB, Barrett PM. 2017 a. A new hypothesis of dinosaur relationships and early dinosaur evolution. Nature 543: 501 - 506."]}

Stenoscelida aurantiacus gen. et sp. nov. (Figs 1–5) Holotype. CAPPA/UFSM 0293, a complete and articulated right hind limb. Etymology. The genus combines the Greek words UIƐvόç (¼ narrow) and UĸƐƛ o ç (¼ hind leg), referring to the slender leg of the creature. The specific epithet derives from the Latin word aurantiacus (¼ orange), in allusion to the orange colour of the outcropping sediments of the Varzea do Agudo site (Fig. 1B). Type locality. Varzea do Agudo site (¼ Janner site; 29 ° 39 0 10.89 00 S, 53 ° 17 0 34.20 00 W), Agudo, Rio Grande do Sul, Brazil (Fig. 1). Stratigraphic horizon. Lower portion of the Candelaria Sequence (Horn et al. 2014) of the Santa Maria Supersequence (Zerfass et al. 2003), Parana Basin. The predominance of the cynodont genus Exaeretodon places the site in the upper part (Exaeretodon sub-Assemblage Zone; Muller & Garcia 2020) of the Hyperodapedon Assemblage Zone (Schultz et al. 2020), which is biostratigraphically correlated with the Exaeretodon biozone from the Ischigualasto Formation (Martınez et al. 2013). A Bayesian age-model for the profile of the Ischigualasto Formation at the Hoyada del Cerro Las Lajas locality in Argentina recovered an age of 227.94 + 0.83/ ¯ 1.67 for the top of the Hyperodapedon AZ (Desojo et al. 2020), indicating an age of c. 228 Ma for the Exaeretodon biozone. A similar age (late Carnian/early Norian, Late Triassic) for the Exaeretodon sub-Assemblage Zone is inferred in the Candelaria Sequence. Ontogenetic assessment. The presence of some muscle attachment structures (e.g. anterior trochanter; anterolateral scar) in the femur of CAPPA/UFSM 0293 suggests some degree of development if the ontogenetic pathways of other archosauriforms are considered (Griffin & Nesbitt 2016). However, it is currently not possible to confirm whether the specimen reached its maximum size or not. Diagnosis. Stenoscelida aurantiacus differs from all other known proterochampsids in (* local autapomorphies): possessing a slender femur; presence of an anterior trochanter on the femoral head; presence of a raised anterolateral scar above the anterior trochanter; fourth trochanter restricted to the proximal half of the femur; tibia approximately 84% the total length of the femur; in proximal view, the cnemial crest of the tibia is subequal in size to the proximal condyles; fibula with an iliofibularis tubercle on the proximal portion of the shaft *; proximal third of the fibular shaft is anteroposteriorly expanded, tapering distally *; ratio between the minimum midshaft width of metatarsal II and its total length is 0.12; ratio between femoral length and metatarsal III is 2.5; and digit V with a phalanx *. Description and comparison Overview The preserved right hind limb of the holotype is entirely articulated (Fig. 2). Some portions of the specimen are covered by a thick concretion layer, especially the femoral midshaft and the ankle. The external surface is wellpreserved in several places, revealing some muscle attachment points. However, the specimen was deformed by sedimentary compression. Therefore, the elements are lateromedially compressed, affecting the original shape. As result, the midshaft of the limb bones is collapsed, showing artificial longitudinal grooves or sulci. Part of the fibular midshaft is not preserved. The same is true for the distal portion of metatarsal IV, precluding us from determining its total length. According to the femoral length (147 mm), the specimen is smaller than the Argentinian taxa from the Ischigualasto Formation: Pseudochampsa ischigualastensis (155 mm; Trotteyn & Ezcurra 2014) and Proterochampsa barrionuevoi (179 mm; Trotteyn 2011). Femur The femur (Fig. 3) is sigmoid in lateral and medial views. The extremities are well ossified and expanded. The femoral head is mainly anteriorly directed, whereas in other proterochampsids it is more medially oriented. Diagenetic processes might have exaggerated this condition. The general morphology of the femoral head resembles that of proterochampsids, whereas it differs from the anteromedially expanded femoral head of dinosaurs (Nesbitt 2011) and from the hook-shaped head of lagerpetids and pterosaurs (Ezcurra et al. 2020a). The proximal articular surface bears a shallow straight groove (Fig. 3C), which is usually absent in proterochampsids, except in an unnamed rhadinosuchine (Ezcurra et al. 2019; CRILAR-Pv 491) from the Chanares Formation. There is an anterior tuber (sensu Ezcurra 2016) on the proximal portion of the femur, and although the bone lacks a posteromedial tuber, the posterior tuber is present. The greater trochanter is rounded and tall (Fig. 3B), differing from the typical angled trochanter of dinosaurs, and in the same way, there is no dorsolateral trochanter on the proximal portion of the bone. Conversely, the anterolateral surface bears a raised and rugose area (Fig. 3B) where the anterior (¼ lesser) trochanter is reported for a number of archosauriforms (e.g. ornithosuchids, aetosaurs, dinosauriforms). Whereas the anterior trochanter is absent in several proterochampsids (Trotteyn et al. 2013), the structure occurs in the holotype of Gualosuchus reigi (PULR-V 05; M. D. Ezcurra, pers. comm.). A trochanteric shelf is not associated with the anterior trochanter, and the proximal-most portion of this trochanter is completely connected to the shaft. Slightly above the proximal tip of the anterior trochanter there is an additional scar, which resembles the anterolateral scar (sensu Griffin & Nesbitt 2016) of aphanosaurs and dinosauriforms. There is a similar scar in Gualosuchus reigi (PULR-V 05; M. D. Ezcurra, pers. comm.). The transition from the femoral head to the shaft is smooth. The fourth trochanter rests on the posterior surface of the proximal third of the femur (Fig. 3A). It is crest-like and symmetrical in shape. Its medial surface is ornamented with muscle scars. The distal portion of the fourth trochanter does not extend further down along the femoral shaft. In contrast, the fourth trochanter is strongly proximodistally developed in Gualosuchus reigi and Chanaresuchus bonapartei (Ezcurra et al. 2019). The midshaft is slender. The robustness index (RI, sensu Wilson & Upchurch 2003; i.e. average of the greatest widths of the proximal end, midshaft and distal end of the element divided by the length of the element) is 0.14. For comparison, this is slightly slenderer than that of some early dinosaurs, such as Gnathovorax cabreirai (0.16) and Buriolestes schultzi (0.15; Muller & Garcia 2022). The anterior surface of the distal portion bears an extensor fossa (Fig. 3D), which results in a concave anterior margin in distal view. On the opposite side, the popliteal fossa is well delimited (Fig. 3E). It is proximodistally short, approximately 10% of the total length of the bone. This condition distinguishes the specimen from silesaurids and aphanosaurs, where the fossa is considerably longer (Nesbitt et al. 2010, 2017). The distal condyles are approximately at the same level in anterior or posterior views. In addition, the lateral surface between the lateral condyle and the crista tibiofibularis is smooth, lacking a deep groove. Tibia The tibia (Fig. 4) is 84% the total length of the femur (Table 1). This resembles the condition in Pseudochampsa ischigualastensis, where it is approximately 82% (Trotteyn & Ezcurra 2014), and differs from both Proterochampsa barrionuevoi (74.5%; Trotteyn 2011) and Tropidosuchus romeri (100%; Arcucci 1990). The bone is straight in anterior/posterior or medial/lateral views. The proximal portion is strongly expanded and is triangular in shape in proximal view (Fig. 4C). The anterior half of the proximal margin is proximally projected in medial view. In medial or lateral views, the well-developed cnemial crest extends anteriorly, and in proximal view it is straight and the anterior margin is rounded. The cnemial crest is sub-equal in size regarding the proximal condyles, distinguishing the new species from Proterochampsa barrionuevoi, where the crest is proportionally smaller. The posterior and lateral condyles are sub-equal in size. The lateral condyle is offset regarding the posterior condyle. The posterior condyle does not taper posteriorly. The presence of any crest on the lateral surface of the proximal portion of the bone is uncertain. The midshaft is ovoid in cross-section. The bone wall is thick, distinct from the thin walls of several pan-avians and some crocodylomorphs (Kellner et al. 2022). The distal portion of the bone is moderately expanded. It lacks a posterolateral process. There is a proximodistally oriented groove on the lateral surface of the distal portion (Fig. 4F). It is more pronounced in Proterochampsa barrionuevoi (Trotteyn 2011). The distal outline of the tibia is elliptical. It is anteroposteriorly longer than transversely wide. · Fibula The total length of the fibula (Fig. 4) is uncertain because a portion of the midshaft is not preserved. The bone is straight in anterior or lateral views, and the proximal articular surface is anteroposteriorly expanded and transversely compressed (Fig. 4C). It differs from the rounded to elliptical proximal end of some pseudosuchians (e.g. Dynamosuchus collisensis, Prestosuchus chiniquensis). In proximal view, the lateral margin is convex but the medial margin is concave. In lateral view, the posterior margin projects posteriorly, whereas the anterior margin lacks any anterior expansion. Conversely, in non-proterochampsid proterochampsians (e.g. Vancleavea campi; Litorosuchus somnii; Jaxtasuchus salomoni) the proximal portion is symmetrical to nearly symmetrical in lateral view. The posterior margin of the proximal third of the bone is sharp. The proximal third of the midshaft is anteroposteriorly expanded, being wider than the tibia (Fig. 4F). Conversely, the shaft becomes extremely slender for the next two-thirds, being approximately two times narrower than the tibia. This is an unusual condition and distinguishes the specimen from other proterochampsids. Furthermore, there is an iliofibularis tubercle on the proximal portion of the shaft (Fig. 4E, F), a feature absent in other proterochampsids. The condition in Stenoscelida aurantiacus differs from the more distally located tubercle of several pseudosuchians and rhynchosaurs. The distal portion of the fibula is gently expanded. It is approximately 0.45 times the maximum length of the proximal articular surface (Table 1). There is a faint longitudinal ridge running on the anterolateral margin. The distal articular surface is flat to concave. In distal view (Fig. 4D), it is ovoid to triangular. Proximal tarsals The astragalus and calcaneum are poorly preserved (Figs 2, 5). The astragalus is transversely wider (20.5 mm) than anteroposteriorly long (11 mm). The anterior margin of the astragalus is concave in dorsal view (Figs 2B, 5B). A transverse groove runs on the posterior surface of the bone. The presence or absence of foramina on this posterior groove is uncertain because it is badly preserved. As in other proterochampsids, the tibial facet is wider than the fibular facet. The latter facet is dorsolaterally oriented, resembling the condition of Chanaresuchus bonapartei and Proterochampsa barrionuevoi, whereas in Pseudochampsa ischigualastensis it is dorsally oriented (Trotteyn & Ezcurra 2014). The ventral surface of the bone is transversely convex. The calcaneum is 10 mm in width (approximately half of the astragalar width). There is a posterolaterally oriented calcaneal tuber. This structure is sub-rectangular, with a straight lateral margin. In dorsal view, the posterolateral corner of the calcaneal tuber is rounded (Fig. 5B). Metatarsals As in other proterochampsids, the metatarsals (Fig. 5) overlap each other. Metatarsal I is shorter than metatarsals II–IV (Fig. 5C). It is almost three times shorter than metatarsal III (Table 1). The proximal articular surface is transversely expanded. There is a longitudinal smooth crest on the dorsomedial corner of the proximal half of the bone. The distal end is moderately expanded. The lateral condyle is more pronounced dorsally than the medial one. There is a shallow extensor fossa on the dorsal surface of the distal portion. The presence of collateral ligament pits on the condylar sides is uncertain. The distal articular surface is not strongly ginglymoid. Metatarsal II is the stoutest metatarsal. The proximal articular surface is strongly expanded (Table 1). The ratio between the proximal articular surface and the total length is 0.39. It is 0.36 in Rhadinosuchus gracilis (Ezcurra et al. 2015). Conversely, the shaft is stouter in Rhadinosuchus gracilis, where the ratio between the minimum midshaft width and the total length of metatarsal II is 0.17. In Stenoscelida aurantiacus it is 0.12. On the dorsal surface of the distal portion, there is a triangular extensor fossa. It is not possible to determine if the articular surface is ginglymoid. There is no evidence of a collateral ligament pit on the medial surface of the medial condyle. On the other hand, the lateral surface of the lateral condyle bears a well-delimited collateral ligament pit (Fig. 5B). In dorsal view, the lateral condyle is straight, whereas the medial condyle is slightly medially oriented. Both condyles are equally expanded distally, which is distinct from Rhadinosuchus gracilis, where the lateral condyle is far more extended distally (Ezcurra et al. 2015). Metatarsal III is the longest (Table 1), whereas its midshaft is slenderer than that of metatarsal II. Its proximal articular surface is moderately expanded (maximum proximal width is 14 mm), far less than the proximal articular surface of metatarsal II (19 mm). The distal articular surface resembles that of metatarsal II, with a marked extensor fossa on the dorsal surface and a collateral ligament pit on the lateral surface of the lateral condyle (Fig. 5B). The presence of the collateral ligament pit on the medial condyle is uncertain (it is covered by thick sediment). The lateral condyle is slightly more pronounced laterally than the lateral condyle of metatarsal II. Metatarsal IV is incomplete (Fig. 5B). The element does not preserve the distal portion. Therefore, its total length is uncertain. The preserved part is 30 mm in length. Despite its condition, the element is longer than metatarsals I and V. The proximal articular surface is not transversely expanded. The general morphology of the element is simple. It comprises an elongated and compressed shaft. Distinct from the previous metatarsals, metatarsal IV is plate-like in cross-section. Metatarsal V is the shortest (Fig. 5B), being slightly shorter than phalanx 1 of digit I. In this sense, Stenoscelida aurantiacus differs from Pseudochampsa ischigualastensis, where metatarsal V is slightly longer than the phalanx 1 from digit I (Trotteyn & Ezcurra 2014). The proximal articular surface is moderately expanded and ‘U’-shaped in ventral view. The shaft tapers distally to an unexpanded and featureless distal end, which bears no distal condyles. Phalanges The phalangeal formula is 2-3-4-?-1 (Fig. 5). Other proterochampsids lack phalanges in digit V. The first phalanx of digit I is longer than broad. This is the same pattern observed in the other phalanges of the specimen. This phalanx is shorter than the first phalanx from digits II and III (Table 2). The dorsal intercondylar process is moderately developed and the distal articular surface is ginglymoid. There is an extensor depression on the dorsal surface of the distal portion. This surface receives the extensor tubercle from the ungual phalanx. The ungual (distal-most) phalanx of digit I lacks its distal half. The phalanx is transversely compressed and tapers distally (at least, the preserved portion). The flexor tubercle is poorly developed (Fig. 5A). The first phalanx of digit II is similar in shape to that of digit I. However, the phalanx from digit II is larger (Fig. 5C). Phalanx 2 is slightly smaller. Its anatomy is obscured by a thick layer of concretion. The ungual phalanx of digit II is clearly the largest ungual. It is transversely compressed and tapers to a sharp point. The ungual is not ventrally recurved and lacks a well-developed flexor tubercle. Digit III is the longest (Fig. 5B). The first phalanx from digit III is sub-equal in length to the first phalanx of digit II (Table 2). On the other hand, the shaft of this phalanx is more gracile. The extensor fossa is deep on the dorsal surface of the distal portion. The subsequent phalanges of this digit are smaller. The ungual is remarkably smaller than that of digit II. The number of phalanges in digit IV is unknown and the distal portion of metatarsal IV is not preserved. Therefore, the absence of phalanges is ambiguous. The phalanx of digit V (Fig. 5A) is reduced to an elongated structure with a concave proximal articular surface. No condyles or other structures are present in this vestigial element. Phylogenetic results The phylogenetic analysis recovered 39,200 most parsimonious trees (MPTs) of 6287 steps (consistency index ¼ 0.18375; retention index ¼ 0.63457). Stenoscelida aurantiacus nests within Proterochampsidae in all MPTs (Fig. 6A). The clade is supported by 19 synapomorphies, of which three are coded for Stenoscelida aurantiacus: 1) midshaft diameter of metatarsal II is more than the midshaft diameter of metatarsal I (ch. 572: 0 ! 1); 2) midshaft diameter of metatarsal IV is lower than that of metatarsal III (ch. 573: 0 ! 1); and 3) crest-like fourth trochanter, dorsoventrally/anteroposteriorly taller than or equal to the shaft at its minimum depth (ch. 803: 1 ! 2). Proterochampsidae is the sister group to Doswelliidae, which is composed of Rugarhynchus sixmilensis, Sphodrosaurus pennsylvanicus, Doswellia kaltenbachi and Jaxtasuchus salomoni. The clade supporting Proterochampsidae + Doswelliidae is in a trichotomy with Polymorphodon adorfi and an unnamed clade composed of Vancleavea campi and Litorosuchus somnii. These clades are included within Proterochampsia. Regarding the internal relationships of Proterochampsidae, there is a polytomy composed of Stenoscelida aurantiacus, Tropidosuchus romeri, Cerritosaurus binsfeldi, Gualosuchus reigi, both species of Proterochampsa, and Rhadinosuchinae in the strict consensus tree (Fig. 6A). Given the absence of overlapping elements between the new taxon and several other proterochampsids (e.g. Proterochampsa nodosa, Cerritosaurus binsfeldi), these unresolved affinities are unsurprising. The new taxon, however, does not nest within Rhadinosuchinae in any of the MPTs, thus Stenoscelida aurantiacus is a non-rhadinosuchine proterochampsid. The clade Rhadinosuchinae is composed of a trichotomy including Rhadinosuchus gracilis, Pse, Published as part of Müller, Rodrigo Temp, Garcia, Mauricio Silva & Fonseca, André de Oliveira, 2022, A new proterochampsid (Archosauriformes: Proterochampsia) from the Late Triassic of southern Brazil and the emergence of archosaurian hind limb traits, pp. 1-19 in Journal of Systematic Palaeontology 20 (1) on pages 3-15, DOI: 10.1080/14772019.2022.2128913, http://zenodo.org/record/7331376, {"references":["Horn, B., Melo, T., Schultz, C., Philipp, R., Kloss, H. & Goldberg, K. 2014. A new third-order sequence stratigraphic framework applied to the Triassic of the Parana Basin, Rio Grande do Sul, Brazil, based on structural, stratigraphic and paleontological data. Journal of South American Earth Sciences, 55, 123 - 132.","Zerfass, H., Lavina, E. L., Schultz, C. L., Garcia, A. J. V., Faccini, U. F. & Chemale, F. Jr. 2003. 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Whereas ornithischian dinosaurs are well known from Jurassic and Cretaceous deposits, deciphering the origin and early evolution of the group remains one of the hardest challenges for palaeontologists. So far, there are no unequivocal records of ornithischians from Triassic beds. Here, we present an alternative evolutionary hypothesis that suggests consideration of traditional ‘silesaurids' as a group of low-diversity clades representing a stem group leading to core ornithischians (i.e. unambiguous ornithischians, such as Heterodontosaurus tucki). This is particularly interesting because it fills most of the ghost lineages that emerge from the Triassic. Following the present hypothesis, the lineage that encompasses the Jurassic ornithischians evolved from ‘silesaurids' during the Middle to early Late Triassic, while typical ‘silesaurids' shared the land ecosystems with their relatives until the Late Triassic, when the group completely vanished. Therefore, Ornithischia changes from an obscure to a well-documented clade in the Triassic and is represented by records from Gondwana and Laurasia. Furthermore, according to the present hypothesis, Ornithischia was the first group of dinosaurs to adopt an omnivorous/herbivorous diet. However, this behaviour was achieved as a secondary step instead of an ancestral condition for ornithischians, as the earliest member of the clade is a faunivorous taxon. This pattern was subsequently followed by sauropodomorph dinosaurs. Indeed, the present scenario favours the independent acquisition of an herbivorous diet for ornithischians and sauropodomorphs during the Triassic, whereas the previous hypotheses suggested the independent acquisition for sauropodomorphs, ornithischians, and ‘silesaurids'.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES The origin and early irradiation of sauropodomorph dinosaurs received much attention in response of new discoveries from fossiliferous strata from South America. However, there are still doubts regarding the transitionary period from carnivorous to herbivorous feeding behaviour and the ecological shift in which sauropodomorphs became the most abundant large vertebrates from their faunas. Moreover, there are several disputes regarding the phylogenetic affinities of triassic sauropodomorphs. Thus, in the present thesis, some sauropodomorphs yielded from Triassic strata of Rio Grande do Sul are studied in order to produce new information on these issues. Among the main results, it was noted that the morphological disparity resulting from ontogenetic variation is high in basal forms, affecting the recovered topologies. Similarly, the sedimentary compression impacts character codification, resulting in artificial scores. The excellent preservation degree of one of the studied specimens (CAPPA/UFSM 0035) provides a better understanding of the anatomy of the earliest sauropodomorphs. In addition, the specimen reinforces the hypothesis that sauropodomorphs evolved from a carnivorous ancestor and accumulated traits related to an herbivorous diet during a second evolutionary moment. The morphological transition of the clade could also be tracked through findings from Rio Grande do Sul strata, including the skeletons that compose CAPPA/UFSM 0001 (another specimen studied in the present thesis). Indeed, these specimens allow to track the modifications on the body plan of sauropodomorphs during a time interval of eight million years, revealing a plausible scenario where the clade changes from small and rare to large and abundant animals. CAPPA/UFSM 0001, a new taxon, also brings new data regarding the biology of sauropodomorphs, suggesting the oldest evidence of gregarious behaviour for the clade. Finally, a new phylogenetic analysis employing a new data matrix revealed a rich diversity of non-plateosaurian sauropodomorphs, still poorly studied. This new hypothesis helps to understand how were the first moments of diversification of the group and how was their dispersion during their first phase of irradiation. A origem e a irradiação inicial dos dinossauros sauropodomorfos tem recebido bastante atenção em virtude de novas descobertas realizadas em estratos fossilíferos da América do Sul. Porém, ainda restam muitas dúvidas a respeito de como foi a fase de transição entre o hábito alimentar carnívoro para uma dieta herbívora e também como foi a mudança ecológica que fez com que os sauropodomorfos passassem a ser, durante o Noriano, os animais de grande porte mais abundantes das faunas onde eles ocorrem. Somam-se ainda as disputas filogenéticas envolvendo sauropodomorfos triássicos. Deste modo, com o objetivo de levantar novas informações a respeito desses temas, nesta tese são estudados materiais coletados em unidades triássicas do Rio Grande do Sul. Dentre os principais resultados, observa-se que disparidade morfológica resultante de variação ontogenética é elevada em formas basais do grupo, podendo causar impacto sobre as topologias. Da mesma forma, notou-se que a codificação de caracteres morfológicos pode também ser influenciada por compressão sedimentar, resultando em estados de caracteres artificiais. O excelente grau de preservação de um dos espécimes estudados (CAPPA/UFSM 0035) possibilitou uma melhor compreensão a respeito da anatomia dos primeiros sauropodomorfos. Além disso, o espécime reforça a hipótese de que os sauropodomorfos tiveram origem a partir de um ancestral carnívoro e passaram a acumular traços dentários relacionados a uma dieta mais voltada à herbivoria apenas em um segundo momento da história evolutiva do grupo. A transição morfológica do clado pôde também ser acompanhada a partir das descobertas realizadas em estratos do Rio Grande do Sul, incluindo os esqueletos referentes a CAPPA/UFSM 0001 (outro dos espécimes estudados nesta tese). De fato, esses espécimes permitiram traçar alterações que ocorreram no plano corpóreo dos sauropodomorfos durante um intervalo de oito milhões de anos, revelando um cenário plausível de como o clado passou de formas pequenas e raras a animais grandes e abundantes. Além de corresponder a um novo táxon, CAPPA/UFSM 0001 também trouxe novos dados referentes à biologia dos sauropodomorfos, sugerindo a mais antiga evidencia de gregarismo para o clado. Por fim, uma análise filogenética adotando uma nova matriz de dados revelou uma rica diversidade de formas basais a Plateosauria que são ainda pouco investigadas. Essa nova hipótese ajuda a entender como foram os primeiros momentos de diversificação do grupo e como foi a dispersão dos sauropodomorfos durante sua fase inicial de irradiação.

Trucidocynodon riograndensis Oliveira, Soares & Schultz, 2010 (FIGS. 2–8; TAbLE 1) Holotype: UFRGS PV-1051-T, ALMOST COMPLETE SkELETON (OLIVEIRA et al. 2010). Paratypes: UFRGS PV-1053-T, RIGHT SCAPULAR GIRDLE, AND fORELIMb; UFRGS PV-1069-T, fIVE VERTEbRAE, AND SOME fRAGMENTARY RIbS; UFRGS PV-1070-T, A RIGHT TIbIA; UFRGS PV-1071-T, RIGHT ULNA (OLIVEIRA et al. 2010). Diagnosis: SEE OLIVEIRA et al. 2010. New Referred specimen: CAPPA / UFSM 0 0 29, A COMPLETE SkULL INCLUDING ARTICULATED LOWER jAW. Locality and horizon: CAPPA / UFSM 0 0 29 COMES fROM THE JANNER OUTCROP, MUNICIPALITY Of AGUDO, STATE Of RIO GRANDE DO SUL, BRAzIL, WHICH IS INCLUDED IN THE LOWER PORTION Of THE CANDELáRIA SEqUENCE (HORN et al. 2014), Hyperodapedon AZ, SANTA MARIA SUPERSEqUENCE (ZERfASS et al. 2003). Description and comparison: Premaxilla. CAPPA / UFSM 0 0 29 PRESERVES bOTH PREMAXILLAE (FIGS. 2–5). THE MAIN bODY Of THIS ELEMENT IS PROPORTIONALLY LARGER THAN IN TRAVERSODONTID CYNODONTS (E.G., Exaeretodon riograndensis), WITH PROPORTIONS RESEMbLING THOSE Of OTHER ECTENINIIDS. THE INTERNARIAL PROCESS Of CAPPA/UFSM 0 0 29 IS TALL bUT DOES NOT REACH THE NASALS (FIGS. 2–5). IN LATERAL VIEW, IT IS DORSALLY DIRECTED IN ITS VENTRAL HALf, WHEREAS THE DORSAL PART IS DORSOPOSTERIORLY DIRECTED, SIMILARLY TO Ecteninion lunensis. THIS STRUCTURE IS SIGMOID IN LATERAL VIEW IN Diegocanis elegans (ALTHOUGH THIS COULD bE TAPHONOMIC), AND IN THE HOLOTYPE Of Trucidocynodon riograndensis IT IS MISSING (OLIVEIRA et al. 2010). THE POSTEROLATERAL ASCENDING PROCESS IS LONG AND REACHES THE DORSAL LEVEL Of THE EXTERNAL NARES, bUT DOES NOT CONTACT THE NASAL, SIMILAR TO THE CONDITION Of HOLOTYPE UFRGS PV-1051-T AND Chiniquodon sanjuanensis (PVSJ 411). IN CONTRAST, IT IS SHORT IN E. lunensis AND D. elegans (MARTÍNEz et al. 2013). THE POSTEROVENTRAL bORDER Of THE PREMAXILLA CONTACTS THE ANTEROVENTRAL MARGIN Of THE MAXILLA AT THE LEVEL Of THE fOURTH UPPER INCISOR, AS IN THE HOLOTYPE Of T. riograndensis, E. lunensis, AND D. elegans (MARTÍNEz et al. 1996; 2013; OLIVEIRA et al. 2010). IN DORSAL VIEW, THE POSTEROLATERAL ASCENDING PROCESS Of THE PREMAXILLA Of CAPPA/UFSM 0 0 29 ENDS AT THE ANTERIOR bORDER Of THE PARACANINE fOSSA, WHICH IS OPENED DORSALLY (FIGS. 2–5, 8). Septomaxilla. BOTH SEPTOMAXILLAE ARE ALMOST COMPLETE, AND ONLY THE LEfT PORTION Of THE INTRANARIAL PROCESS (= MEDIAL LAMINA) (SEE HILLENIUS 2000; SIDOR 2003) IS MISSING (FIGS. 2–5). THE RIGHT INTRANARIAL PROCESS COVERS THE DORSAL SURfACE Of THE PREMAXILLA IN CAPPA/UFSM 0 0 29. IT IS VENTRALLY CONVEX, DORSALLY CONCAVE, AND EXTENDS TOWARDS THE MIDLINE, SEPARATED fROM THE NARIAL fLOOR, AS IN D. elegans. THE fACIAL (=ASCENDING) PROCESS APPEARS TO bE PROPORTIONALLY LESS DEVELOPED THAN IN E. lunensis AND D. elegans. THE DORSAL PORTION Of THE fACIAL PROCESS RUNS POSTERODORSALLY, CONTACTS THE POSTEROLATERAL ASCENDING PROCESS Of THE PREMAXILLA, AND DELIMITATES THE POSTEROLATERAL bORDER Of THE EXTERNAL NARES. THE OPENING Of THE SEPTOMAXILLARY fORAMEN IS UNCERTAIN. Maxilla. BOTH ELEMENTS ARE ENTIRELY PRESERVED (FIGS. 2–5). THEY ARE SUbRECTANGULAR IN LATERAL VIEW AND DORSOVENTRALLY DEEP, A CONDITION fOUND IN OTHER ECTENINIIDS. THE MAXILLA OCCUPIES ALMOST ENTIRELY THE LATERAL SURfACE Of THE PREORbITAL REGION Of THE SkULL (OLIVEIRA et al. 2010). AS IN OTHER EUCYNODONTS, SUCH AS Lumkuia fuzzi HOPSON & KITCHING, 2001 AND C. sanjuanensis, THE MAXILLA REACHES ITS GREATEST HEIGHT AT THE LEVEL Of THE CANINE ROOT (MARTÍNEz et al. 2013). ALSO, THE DORSAL MARGIN Of THE MAXILLA IS ANTEROPOSTERIORLY SHORTER IN COMPARISON TO THE VENTRAL MARGIN (FIG. 4), AS IN E. lunensis AND THE HOLOTYPE Of T. riograndensis, WHEREAS IN D. elegans IT IS LESS PRONOUNCED. AS IN OTHER ECTENINIIDS, CAPPA/UFSM 0 0 29 PRESENTS TWO ANTEROPOSTERIORLY ALIGNED INfRAORbITAL fORAMINA IN THE MIDDLE REGION Of THE MAXILLA, HOWEVER, IN E. lunensis AND D. elegans, A THIRD INfRAORbITAL fORAMEN IS OPENED LATERALLY AT THE POINT WHERE LACRIMAL, jUGAL AND MAXILLA CONTACT (MARTÍNEz et al. 1996; 2013). THE POSTERIOR PORTION Of THE MAXILLA CONTACTS THE jUGAL POSTEROVENTRALLY, fORMING THE ANTERIOR ROOT Of THE zYGOMATIC ARCH, THE LACRIMAL POSTERODORSALLY, AND THE NASAL MARGIN DORSALLY (FIGS. 2–5). THE ANTERODORSAL MARGIN Of THE MAXILLA RUNS ALONG THE NASAL AND MEETS THE EXTERNAL DORSAL OPENING Of THE PARACANINE fOSSA AT THE LEVEL Of THE UPPER CANINE ROOT. COMPARISON Of THE TWO SIDES DEMONSTRATES THAT THE DORSAL OPENING Of THE PARACANINE fOSSAE IS SLIGHTLY DEfORMED. THIS STRUCTURE IS bETTER PRESERVED ON THE LEfT SIDE. THE RIGHT EDGES Of THE PARACANINE fOSSA MEASURE 6 MM ANTEROPOSTERIORLY AND 13 MM DORSOVENTRALLY (FIG. 2). CONVERSELY, THE LEfT PARACANINE fOSSA MEASURES 6 MM ANTEROPOSTERIORLY AND 8 MM DORSOVENTRALLY (FIG. 3). IN CONTRAST TO D. elegans, IN CAPPA/UFSM 0 0 29, UFRGS PV- 1051-T, AND E. lunensis THE PARACANINE fOSSAE ARE OPEN DORSALLY (FIGS. 4, 8), WHICH ALLOWS THE TIPS Of THE LOWER CANINES TO PROTRUDE THROUGH THE ROOf Of THE SNOUT (MARTÍNEz et al. 2013). Nasal. CAPPA/UFSM 0 0 29 PRESERVES bOTH NASALS (FIGS. 2–5). THEY COMPRISE APPROXIMATELY 44% Of THE TOTAL SkULL LENGTH. MEDIALLY, THE NASALS CONTACT EACH OTHER IN A STRAIGHT SUTURE. ON ITS ANTERIOR HALf, THERE IS A SMALL ELEVATION (ANTEROPOSTERIOR CONVEXITY) CLOSE TO THE DORSAL PREMAXILLARY bORDER. IN THE HOLOTYPE Of T. riograndensis AND E. lunensis, THIS REGION IS RELATIVELY fLAT IN COMPARISON WITH ITS REMAINING DORSAL SURfACE. IN D. elegans, THE ENTIRE DORSAL PROfILE Of THE NASAL IS fLAT IN LATERAL VIEW. IT IS PLAUSIbLE THAT THIS DORSAL CONVEXITY IN CAPPA/UFSM 0 0 29 IS AN ARTIfACT Of PRESERVATION bECAUSE THIS REGION IS EXPANDED bY DIAGENESIS (FIG. 4). AS IN OTHER EUCYNODONTS (E.G., HOLOTYPE Of T. riograndensis, Probainognathus jenseni, Chiniquodon theotonicus VON HUENE, 1936), IN DORSAL VIEW THE NASAL IS CURVED ON THE LEVEL Of THE POSTCANINE CONSTRICTION, WHEREAS IN D. elegans IT GENTLY TAPERS fROM THE ANTERIOR END TO THE LEVEL Of THE POSTCANINE CONSTRICTION (MARTÍNEz et al. 2013). LATERALLY, THE NASAL CONTACTS THE MAXILLA (FIGS. 2–5). ALSO, IT EXPANDS POSTEROLATERALLY CLOSE TO THE LEVEL Of THE ANTERIOR bORDER Of THE ORbIT, SO THAT ITS POSTEROMEDIAL bORDER CONTACTS THE ANTERIOR MARGIN Of THE fRONTAL. ITS POSTEROLATERAL bORDER CONTACTS THE ANTEROMEDIAL MARGIN Of THE PREfRONTAL AND THE ANTEROMEDIAL MARGIN Of THE LACRIMAL. IN D. elegans THE NASAL SLIGHTLY CONTACTS THE PREfRONTAL, IN CONTRAST TO THE CONDITION IN CAPPA/UFSM 0 0 29, UFRGS PV-1051-T, AND E. lunensis, WHERE THE CONTACT bETWEEN THESE bONES IS EXTENSIVE. Lacrimal. BOTH ELEMENTS ARE ALMOST COMPLETE, LACkING jUST A SMALL fRAGMENT Of THE POSTEROVENTRAL END Of THE RIGHT ELEMENT (FIGS. 2–4). AS IN THE OTHER ECTENINIIDS, THE LACRIMAL IS ANTEROPOSTERIORLY SHORT, IN CONTRAST TO C. theotonicus, IN WHICH THE LACRIMAL IS ANTERIORLY DEVELOPED, WITH A TRIANGULAR SHAPE IN LATERAL VIEW. THE ANTERIOR LACRIMAL MARGIN IS ROUNDED, fORMING THE ANTERIOR AND VENTRAL ORbITAL RIM. POSTERODORSALLY, THE LACRIMAL CONTACTS THE PREfRONTAL AND THE ANTEROVENTRAL PORTION Of THE jUGAL (FIGS. 2–4). THE ANTERODORSAL MARGIN Of THE LACRIMAL CONTACTS THE NASAL, WHEREAS ITS ANTEROVENTRAL PORTION CONTACTS THE MAXILLA. IN CAPPA/UFSM 0 0 29, AS IN THE HOLOTYPE Of T. riograndensis, THE LACRIMAL IS REDUCED, bECAUSE IT DOES NOT PRESENT A POSTERIORLY DIRECTED VENTRAL PROCESS THAT fORMS A PRONOUNCED RIDGE IN THE ORbITAL MARGIN, A CONDITION fOUND IN D. elegans, E. lunensis (MARTÍNEz et al. 2013), AND ICTIDOSAURS (E.G., Riograndia guaibensis BONAPARTE et al. 2001; SOARES et al. 2011). THE LACRIMAL Of D. elegans IS DORSOVENTRALLY MORE EXPANDED THAN THAT IN OTHER ECTENINIIDS. THUS, THIS ELEMENT POSSIbLY POSSESSES A LARGE DORSOLATERAL CONTACT WITH THE NASAL AND SIGNIfICANT PARTICIPATION IN THE ORbITAL MARGIN. Prefrontal. BOTH ELEMENTS ARE ENTIRELY PRESERVED IN CAPPA/UFSM 0029; THEY ARE RECTANGULAR AND POSTEROMEDIALLY EXPANDED, WHERE THEY CONTACT THE fRONTALS (FIGS. 2–4). IN DORSAL VIEW, THE PREfRONTALS ARE SMALLER THAN THOSE Of TRAVERSODONTIDS (FIG. 4) (E.G., Exaeretodon riograndensis), IN WHICH THIS bONE IS WIDE AND qUADRANGULAR bONE (AbDALA et al. 2002). CONVERSELY, IN D. elegans AND E. lunensis THE PREfRONTALS ARE NARROWER THAN CAPPA/UFSM 0 0 29 AND UFRGS PV-1051-T AND LACk A POSTEROMEDIAL EXPANSION. THE PREfRONTAL fORMS MOST Of THE DORSAL bORDER Of THE ORbITAL RIM. ANTEROMEDIALLY, THE PREfRONTAL CONTACTS THE POSTEROLATERAL PORTION Of THE NASAL AND ANTEROLATERALLY THE DORSAL MARGIN Of THE LACRIMAL, AS IN THE HOLOTYPE Of T. riograndensis AND E. lunensis, bUT DIffERENTLY fROM D. elegans IN WHICH THE bONE IS MORE ANTERIORLY EXPANDED fORMING A TINY ANTEROMEDIAL CONTACT WITH THE NASAL AND THE LACRIMAL (MARTÍNEz et al. 2013). MEDIALLY, IT CONTACTS THE LATERAL bORDER Of THE fRONTAL AND, POSTERIORLY, THE ANTERODORSAL MARGIN Of THE POSTORbITAL. Frontal. BOTH ELEMENTS ARE COMPLETE AND PLACED IN THE CENTRAL PORTION Of THE SkULL ROOf (FIG. 4). TOGETHER, THEY HAVE THE SHAPE Of LOzENGE IN DORSAL VIEW, WITH A POSTERIORLY PROjECTED WEDGED PORTION. THE fRONTALS ARTICULATE AGAINST EACH OTHER, fORMING A SMALL MIDLINE CREST THAT TAPERS POSTERIORLY, CONTACTING THE PARIETALS (FIG. 4). IN UFRGS PV-1051-T AND E. lunensis, THE fRONTALS fORM AN AXIAL, fLAT CREST, AND IN D. elegans THE SUTURE bETWEEN fRONTALS IS NOT VISIbLE DUE TO POOR PRESERVATION. THE ANTEROPOSTERIOR LENGTH Of THE fRONTALS IS LARGER THAN THE TRANSVERSE WIDTH. IN CAPPA/UFSM 0 0 29, THE fRONTALS HAVE A LONG POSTEROLATERAL CONTACT WITH THE POSTORbITALS AND A COMPARATIVELY SHORTER ANTEROLATERAL CONTACT WITH THE PREfRONTAL bONES (FIG. 4). THEY ALSO CONTACT THE NASALS ANTERIORLY AND THE PARIETALS POSTEROLATERALLY. IN DORSAL VIEW, THE fRONTAL HAS TWO DEPRESSIONS IN THE ANTEROLATERAL REGION (FIG. 4), WHICH COULD bE AN INDICATION Of A CIRCULAR fORAMEN AS THIS fEATURE IS PRESENT ON THE POSTEROLATERAL PORTION IN E. lunensis (MARTÍNEz et al. 1996). THE fRONTALS Of CAPPA/UFSM 0 0 29 DO NOT CONTACT THE ORbITAL MARGIN, AS IN MOST NON- MAMMALIAfORM CYNODONTS (E.G., ECTENINIIDS, Probainognathus jenseni, Lumkuia fuzzi, AND Exaeretodon riograndensis). THE SUTURES IN THE ORbITAL WALL CANNOT bE ObSERVED bECAUSE THE INTERNAL ORbITAL REGION IS DAMAGED. HOWEVER, INSIDE THE ORbIT, THE fRONTALS Of THE HOLOTYPE Of T. riograndensis, E. lunensis, AND D. elegans EXTEND VENTRALLY TO fORM PART Of THE INNER ORbITAL WALL, CONTACTING THE LACRIMAL ANTERIORLY, THE PREfRONTAL LATERODORSALLY, AND THE PALATINE VENTRALLY (MARTÍNEz et al. 1996; 2013). Parietal. THE PARIETALS Of CAPPA/UFSM 0 0 29 ARE ELONGATE AND fUSED TO EACH OTHER (FIGS. 2–4). THEY COMPRISE APPROXIMATELY 37% Of THE TOTAL SkULL LENGTH IN DORSAL VIEW AND fORM A TALL SAGITTAL CREST THAT ARISES IMMEDIATELY bEHIND Of THE LEVEL Of THE POSTERIOR ORbITAL MARGIN AND EXTENDS POSTERIORLY TO REACH THE ANTERIOR-MOST PORTION Of THE OCCIPITAL (=LAMbDOIDAL) CREST. ANTERIORLY, THE PARIETALS CONTACT THE POSTEROMEDIAL PORTION Of THE fRONTALS AND POSTORbITALS (FIG. 4). POSTERIORLY, THE PARIETAL CONTACTS THE INTERPARIETAL, WHICH CONTRIbUTES TO THE POSTERIOR PORTION Of THE SAGITTAL CREST AND POSTEROVENTRALLY CONTACTS THE SqUAMOSAL, bUT THERE IS NO CLEAR SIGN Of SUTURES bETWEEN THESE bONES (FIG. 4). THUS, IT IS NOT POSSIbLE TO ObSERVE If THE SqUAMOSAL Of CAPPA/UFSM 0 0 29 CONTRIbUTES TO THE fORMATION Of THE SAGITTAL CREST OR PARTICIPATES ONLY IN THE LATERAL PORTION Of THE OCCIPITAL CREST. IN T. riograndensis (UFRGS PV-1051-T) THE SqUAMOSAL CONTRIbUTES ONLY TO THE LATERAL PORTION Of THE OCCIPITAL CREST. IN CONTRAST, IN E. lunensis AND Probainognathus, THE SqUAMOSAL CONTRIbUTES TO THE POSTEROLATERAL PORTION Of THE SAGITTAL CREST AND POSTERIOR PORTION Of THE OCCIPITAL CREST, MORE EXTENSIVELY DEVELOPED IN THE LATTER TAXON (MARTÍNEz et al. 1996). THE PINEAL fORAMEN IS AbSENT, AS IN OTHER PRObAINOGNATHIANS (HOPSON & KITCHING 2001; LIU & OLSEN 2010). Postorbital. CAPPA/UFSM 0 0 29 PRESERVES bOTH POSTORbITALS (FIGS. 2–4). DORSALLY THEY PARTICIPATE IN A SMALL PORTION Of THE SkULL ROOf, AND THEIR SUTURAL CONTACTS ARE CLEAR. THE POSTORbITAL bEARS A POSTERIOR PROCESS WITH A SEMICIRCULAR SHAPE, WHICH EXTENDS POSTERIORLY TOWARDS THE SkULL MIDLINE. THE POSTERIOR PROCESS bROADLY OVERLAPS THE POSTEROLATERAL PORTION Of THE fRONTAL AND THE ANTEROMEDIAL MARGIN Of THE PARIETAL. ANTERIORLY, THE POSTORbITAL ALSO CONTACTS THE POSTERIOR bORDER Of THE PREfRONTAL. THE POSTORbITAL bAR fORMS bOTH POSTERODORSAL AND POSTERIOR ORbITAL MARGIN. IT IS THIN AND SUbCIRCULAR IN CROSS-SECTION, AS IN THE HOLOTYPE Of T. riograndensis, E. lunensis, AND Chiniquodon sanjuanensis (MARTÍNEz & FORSTER 1996; MARTÍNEz et al. 1996; OLIVEIRA et al. 2010). IN D. elegans, THIS CONDITION IS UNkNOWN bECAUSE bOTH THE LEfT POSTORbITAL AND POSTERIOR PORTION Of THE RIGHT ONE ARE NOT PRESERVED. THE POSTORbITAL bAR Of CAPPA/UFSM 0 0 29 CONTRIbUTES A DESCENDING PROCESS, WHICH ANTERIORLY OVERLAPS THE ASCENDING PROCESS Of THE jUGAL (FIG. 3), A CONDITION SHARED WITH THE HOLOTYPE Of T. riograndensis AND E. lunensis (PVSJ 481). ON THE OTHER HAND, THE HOLOTYPE Of E. lunensis (PVSJ 422) DOES NOT PRESERVE THIS REGION. ACCORDING TO OLIVEIRA et al. (2010), T. riograndensis (UFRGS PV-1051-T) PRESENTS A POSSIbLE AUTAPOMORPHIC fEATURE IN THE POSTORbITAL: IT OVERLAPS THE jUGAL IN THE VENTRAL MARGIN Of THE ORbIT. HOWEVER, THIS fEATURE IS NOT AN AUTAPOMORPHY Of HOLOTYPE UFRGS PV-1051-T bUT, INSTEAD, A CONDITION SHARED WITH E. lunensis (PVSJ 481). IN D. elegans THIS fEATURE IS UNkNOWN. Jugal. BOTH SIDES Of THE SPECIMEN PARTIALLY PRESERVE THIS bONE (FIGS. 2–3). A SMALL ANTERIOR PORTION THAT CONTACTS THE LACRIMAL ANTERODORSALLY AND THE MAXILLA ANTERIORLY IS DISPLACED fROM THE RIGHT ELEMENT. IN ADDITION, bOTH POSTERIOR PORTIONS Of THE zYGOMATIC ARCH ARE fRACTURED, AND THE RIGHT ARCH IS bETTER PRESERVED THAN THE LEfT ONE, WHICH IS bROkEN ON ITS POSTERIOR END. THE jUGAL LARGELY CONTRIbUTES TO THE zYGOMATIC ARCH, bUT DUE TO bAD PRESERVATION, THE POSTERIOR CONTACT Of THE jUGAL AND SqUAMOSAL IS UNCERTAIN. COMPARED TO OTHER NON-MAMMALIAfORM CYNODONTS, THE zYGOMATIC ARCH Of CAPPA/UFSM 0 0 29 IS NARROW AND SLENDER, AS IN UFRGS PV-1051-T AND THE PRESERVED ANTERIOR PORTIONS Of THE jUGAL Of D. elegans AND E. lunensis (MARTÍNEz et al. 1996; 2013; OLIVEIRA et al. 2010). ON THE OTHER HAND, THE zYGOMATIC ARCH Of CHINIqUODONTIDS, Probainognathus jenseni, AND OTHER CYNOGNATHIANS (E.G., Exaeretodon riograndensis) IS MORE RObUST. THE jUGAL fORMS APPROXIMATELY 50% Of THE POSTEROVENTRAL ORbITAL RIM (FIG. 2). DORSALLY THE LATERAL PORTION Of THE POSTORbITAL, IN CAPPA/UFSM 0 0 29 AND IN T. riograndensis (UFRGS PV-1051-T) PRESENT A SHORT jUGAL/LACRIMAL CONTACT, IN CONTRAST TO THE CONDITION IN D. elegans AND E. lunensis (SEE MARTÍNEz et al. 1996; 2013). IN THE POSTERIOR PORTION Of THE ORbITAL RIM, THE ASCENDING PROCESS Of THE jUGAL CONTACTS THE DESCENDING PROCESS Of THE POSTORbITAL, WHICH OVERLAPS THE fORMER IN THE ORbITAL MARGIN (FIG. 3), AS IN THE HOLOTYPE Of T. riograndensis (OLIVEIRA et al. 2010) AND E. lunensis (PVSJ 481). Interparietal. THIS bONE IS LIkELY ObSERVAbLE IN DORSAL, LATERAL, AND OCCIPITAL VIEWS, WITH ONLY A SMALL PORTION Of ITS RIGHT DORSAL EDGE MISSING (FIGS. 4, 6). HOWEVER, IT IS NOT POSSIbLE TO ObSERVE ITS SUTURES WITH THE OTHER bONES, AND SO ITS LIMITS MUST REMAIN CONjECTURAL. IN DORSAL VIEW, THE INTERPARIETAL Of CAPPA/UFSM 0 0 29 CONTRIbUTES TO THE POSTERIOR END Of THE SAGITTAL CREST AND PARTICIPATES IN THE POSTERODORSAL PORTION Of THE OCCIPITAL CREST, AS THE HOLOTYPE UFRGS PV-1051-T (SEE OLIVEIRA et al. 2010). AS IN T. riograndensis (UFRGS PV-1051-T) AND E. lunensis, TWO CONCAVITIES ARE VISIbLE IN OCCIPITAL VIEW, IN THE AREA SUPPOSEDLY CLOSE TO THE CONTACT WITH THE TAbULARS. Squamosal. THE SqUAMOSAL Of CAPPA / UFSM 0 0 29 IS POORLY PRESERVED, AND THE SUTURES THAT DELIMIT THIS bONE ARE NOT ObSERVAbLE (FIGS. 2–4, 6–7). THIS ELEMENT IS SIGNIfICANTLY DAMAGED ON bOTH SIDES, AND THE zYGOMATIC ARCHES ARE fRAGMENTED ON THE CONTACT bETWEEN SqUAMOSAL AND jUGAL (FIGS. 2–3). THE LEfT SqUAMOSAL IS bETTER PRESERVED THAN THE RIGHT ONE (FIGS. 2–3). THE AREA Of ARTICULATION Of THE SkULL WITH THE jAW IS DAMAGED. HOWEVER, THERE IS A SMALL ELEMENT THAT MIGHT CORRESPOND TO qUADRATE/qUADRATOjUGAL (FIG. 3). THE SqUAMOSAL ALSO fORMS THE ANTEROVENTRAL PORTION Of THE OCCIPITAL CREST AND A SMALL VENTRAL PART Of THE POSTERIOR REGION Of THE SkULL (FIGS. 4, 7). IN CAPPA / UFSM 0 0 29 AND IN THE HOLOTYPE Of T. riograndensis, THE PTERYGOPAROCCIPITAL fORAMEN OPENS ANTERIORLY INTO THE TEMPORAL fOSSA. IN E. lunensis THIS fORAMEN IS CLOSED bY THE qUADRATE RAMUS Of THE EPIPTERYGOID. DUE TO THE STATE Of PRESERVATION Of CAPPA / UFSM 0 0 29 IN THIS REGION, THE VISUALIzATION Of THE SUTURES IS NOT COMPLETELY POSSIbLE. IN THE LATERAL SURfACE Of THE SqUAMOSAL, THERE IS A DORSOVENTRAL SULCUS (=EXTERNAL AUDITORY MEATUS) (FIGS. 2–3) AND, AT THE POSTERIOR END, THIS bONE PARTICIPATES IN THE OCCIPITAL CREST. THE SqUAMOSAL ALSO fORMS THE POSTERIOR PORTION Of THE LATERAL WALL Of THE OCCIPITAL CREST, IN OCCIPITAL VIEW (FIG. 6). THE SqUAMOSAL EXTENSIVELY CONTACTS THE TAbULAR AND THESE bONES DELIMITATE THE POSTERIOR OPENING Of THE POST-TEMPORAL fORAMEN, AS IN T. riograndensis (UFRGS PV-1051 -T) (OLIVEIRA et al. 2010). CONVERSELY, IN E. lunensis THIS OPENING IS SURROUNDED ENTIRELY bY THE TAbULAR bONE. UNfORTUNATELY, THE VISUALIzATION Of THE SUTURES Of THE SqUAMOSAL WITH THE SURROUNDING bONES IS IMPOSSIbLE IN CAPPA/UFSM 0 0 29, PREVENTING THE ObSERVATION If IT CONTRIbUTES ONLY TO THE POSTERIOR PORTION Of THE LATERAL WALL Of THE OCCIPITAL CREST, AS IN THE HOLOTYPE UFRGS PV-1051-T, OR If IT ALSO CONTRIbUTES TO THE POSTEROLATERAL PORTION Of THE SAGITTAL CREST, AS IN E. lunensis AND Probainognathus (MARTÍNEz et al. 1996). Tabular. CAPPA/UFSM 0 0 29 PRESERVES bOTH TAbULARS (FIG. 6). THEY fORM THE DORSOLATERAL PART Of THE OCCIPUT AND, TOGETHER WITH THE SqUAMOSAL, CONTRIbUTE TO THE DORSOLATERAL AND LATERAL MARGINS Of THE OCCIPITAL CREST, AS IN T. riograndensis (UFRGS PV-1051-T) AND E. lunensis (MARTÍNEz et al. 1996; OLIVEIRA et al. 2010). THE TAbULAR CONTACTS THE INTERPARIETAL DORSOMEDIALLY AND THE SqUAMOSAL LATERALLY, bUT THE EXACT SUTURAL CONTACTS WITH THE SURROUNDING ELEMENTS ARE NOT EVIDENT. Supraoccipital. IN OCCIPITAL VIEW, THE SUPRAOCCIPITAL Of CAPPA / UFSM 0 0 29 DELIMITS ALMOST THE ENTIRE DORSAL MARGIN Of THE fORAMEN MAGNUM. THIS ELEMENT CONTACTS THE INTERPARIETAL DORSALLY, AND THE TAbULARS LATERALLY (FIG. 6). THE CONTACT WITH THE EXOCCIPITAL IS ObSCURED bY INCRUSTATION. THE fORAMEN MAGNUM IS RELATIVELY LARGE AND TRIANGULAR IN OUTLINE (FIG. 6). IN E. lunensis, THE f, Published as part of Stefanello, Micheli, Müller, Rodrigo Temp, Kerber, Leonardo, Martínez, Ricardo N. & Dias-Da-Silva, Sérgio, 2018, Skull anatomy and phylogenetic assessment of a large specimen of Ecteniniidae (Eucynodontia: Probainognathia) from the Upper Triassic of southern Brazil, pp. 351-378 in Zootaxa 4457 (3) on pages 354-366, DOI: 10.11646/zootaxa.4457.3.1, http://zenodo.org/record/1457830

Dromomeron gregorii Nesbitt et al., 2009 (Fig. 1D) Age. early–mid Norian, Late Triassic. Occurrence. Dockum Group, Texas, USA and Chinle Formation, Arizona, USA Holotype. TMM 31100-1306, right femur. Paratypes. TMM 31100-464, right femur; TMM 31100-1308, right femur; TMM 31100-1234, right femur; TMM 31100-764, right femur; TMM 31100-278, right tibia; TMM 31100-1314, left tibia. Referred material. UCMP 25815, distal portion of a left femur; TTU-P11282, left femur; TTU-P18331, proximal end of left femur; TTU-P20046, distal end of left femur; WTAMU-V-8302, proximal end of right femur; WTAMU- V-8303, proximal end of right tibia., Published as part of Müller, Rodrigo Temp, Langer, Max Cardoso & Dias-Da-Silva, Sérgio, 2018, Ingroup relationships of Lagerpetidae (Avemetatarsalia: Dinosauromorpha): a further phylogenetic investigation on the understanding of dinosaur relatives, pp. 149-158 in Zootaxa 4392 (1) on page 151, DOI: 10.11646/zootaxa.4392.1.7, http://zenodo.org/record/1195260, {"references":["Nesbitt, S. J., Irmis, R. B., Parker, W. G., Smith, N. D., Turner, A. H. & Rowe, T. (2009) Hindlimb osteology and distribution of basal dinosauromorphs from the Late Triassic of North America. Journal of Vertebrate paleontology, 29, 498 - 516. https: // doi. org / 10.1671 / 039.029.0218"]}

Dromomeron gigas Martínez et al., 2016 (Fig. 1F) Age. late Norian – Rhaetian, Late Triassic (Martínez et al. 2015). Occurrence. Quebrada Del Barro Formation, Argentina. Holotype. PVSJ 898, a partial left femur represented by its proximal and distal portions., Published as part of Müller, Rodrigo Temp, Langer, Max Cardoso & Dias-Da-Silva, Sérgio, 2018, Ingroup relationships of Lagerpetidae (Avemetatarsalia: Dinosauromorpha): a further phylogenetic investigation on the understanding of dinosaur relatives, pp. 149-158 in Zootaxa 4392 (1) on pages 151-152, DOI: 10.11646/zootaxa.4392.1.7, http://zenodo.org/record/1195260, {"references":["Martinez, R. N., Apaldetti, C., Correa, G. A. & Abelin, D. (2016) A Norian Lagerpetid Dinosauromorph from the Quebrada Del Barro Formation, Northwestern Argentina. Ameghiniana, 53, 1 - 13. https: // doi. org / 10.5710 / AMGH. 21.06.2015.2894","Martinez, R. N., Apaldetti, C., Correa, G., Colombi, C. E., Fernandez, E., Santi Malnis, P., Praderio, A., Abelin, D., Benegas, L., Aguilar Cameo, A. & Alcober, O. A. (2015) A new late Triassic vertebrate assemblage from Northwestern Argentina. Ameghiniana, 52, 379 - 390. https: // doi. org / 10.5710 / AMGH. 27.04.2015.2889"]}

Dromomeron romeri Irmis et al., 2007 (Fig. 1E) Age. Norian, Late Triassic (Irmis et al. 2007). Occurrence. Dockum Group, Texas, USA and Chinle Formation, New Mexico, USA. Holotype. GR 218, left femur. Paratypes. GR 219, right femur; GR 220, left tibia; GR 221, partial left femur; GR 234, right femur; GR 222, left tibia; GR 223, astragalocalcaneum. Referred material. GR 235, partial articulated skeleton; GR 236, partial right tibia; NMMNH P-35379, astragalocalcaneum; AMNH FR 2721, distal portion of a femur; AMNH FR 30648, distal portion of a right tibia; AMNH FR 30649, distal portion of a right tibia; TTU-P12537X, proximal end of right tibia; WTAMU-V-8301, distal end of right femur., Published as part of Müller, Rodrigo Temp, Langer, Max Cardoso & Dias-Da-Silva, Sérgio, 2018, Ingroup relationships of Lagerpetidae (Avemetatarsalia: Dinosauromorpha): a further phylogenetic investigation on the understanding of dinosaur relatives, pp. 149-158 in Zootaxa 4392 (1) on page 151, DOI: 10.11646/zootaxa.4392.1.7, http://zenodo.org/record/1195260, {"references":["Irmis, R. B., Nesbitt, S. J., Padian, K., Smith, N. D., Turner, A. H., Woody, D. & Downs, A. (2007) A Late Triassic dinosauromorph assemblage from New Mexico and the rise of dinosaurs. Science, 317, 358 - 361. https: // doi. org / 10.1126 / science. 1143325"]}

Ixalerpeton polesinensis Cabreira et al., 2016 (Fig. 1B) Age. late Carnian, Late Triassic (Cabreira et al. 2016). Occurrence. Candelária Sequence of the Santa Maria Supersequence, Brazil. Holotype. ULBRA-PVT059, partially articulated skeleton, including skull roof, braincase, 23 pre-sacral, two sacral, and nine tail vertebrae, right scapula, left humerus, paired pelvic girdle, femur, tibia, and fibula. Paratype. ULBRA-PVT058, pair of femora., Published as part of Müller, Rodrigo Temp, Langer, Max Cardoso & Dias-Da-Silva, Sérgio, 2018, Ingroup relationships of Lagerpetidae (Avemetatarsalia: Dinosauromorpha): a further phylogenetic investigation on the understanding of dinosaur relatives, pp. 149-158 in Zootaxa 4392 (1) on page 150, DOI: 10.11646/zootaxa.4392.1.7, http://zenodo.org/record/1195260, {"references":["Cabreira, S. F., Kellner, A. W. A., Dias-da-Silva, S., Roberto-da-Silva, L., Bronzati, M., Marsola, J. C., Muller, R. T., Bittencourt, J. S., Batista, B. J., Raugust, T., Carrilho, R. & Langer, M. C. (2016) A unique Late Triassic dinosauromorph assemblage reveals dinosaur ancestral anatomy and diet. Current Biology, 26, 3090 - 3095. https: // doi. org / 10.1016 / j. cub. 2016.09.040"]}

Dataset taken from Baron et al. (2017) with properly ordered characters.

The rise of sauropodomorphs is still poorly understood due to the scarcity of well-preserved fossils in early Norian rocks. Here, we present an association of complete and exceptionally well-preserved dinosaur skeletons that helps fill that gap. They represent a new species, which is recovered as a member of a clade solely composed of Gondwanan Triassic taxa. The new species allows the definition of a set of anatomical changes that shaped sauropodomorph evolution along a period from 233 to 225 Ma, as recorded in the well dated Late Triassic beds of Brazil. In that time span, apart from achieving a more herbivorous diet, sauropodomorph dinosaurs increased their size in a ratio of 230% and their typical long neck was also established, becoming proportionally twice longer than those of basal taxa. Indeed, the new dinosaur is the oldest-known sauropodomorph with such an elongated neck, suggesting that the ability to feed on high vegetation was a key trait achieved along the early Norian. Finally, the clustered preservation mode of the skeletons represents the oldest evidence of gregarious behaviour among sauropodomorphs.

In the present contribution, we aim to present the osteology of ‘ULBRA-PVT-281’, which comprises the best-preserved skeleton of Prestosuchus chiniquensis ever found. ULBRA-PVT-281 combines the morphology of two classic specimens referred to P. chiniquensis, UFRGS-PV-0156-T and UFRGSPV- 0152-T, reunited in a single operational taxonomic unit (OTU) in previous phylogenetic studies. Therefore, the new specimen reinforces the combination of both specimens. We performed a phylogenetic analysis, combining the information of these three specimens plus braincase data from a fourth specimen, UFRGS-PV-0629-T, into a new P. chiniquensis terminal taxon. Moreover, our analysis also included some new taxa potentially related to P. chiniquensis. As a result, we found a topology slightly distinct from previous studies, where Ticinosuchus ferox is the basalmost member of Loricata, which also includes the new combined P. chiniquensis. Our results place P. chiniquensis, Luperasuchus fractus, and Saurosuchus galilei distributed in a pectinate paraphyletic pattern towards Crocodylomorpha. On the other hand, a constrained analysis forcing the monophyly of these taxa demands just a single extra step. Therefore, both scenarios are plausible and agree with the placement of P. chiniquensis within Loricata, whereas T. ferox nests in Loricata only in the unconstrained analysis.