Saturnalia tupiniquim Langer et al. 1999

Saturnalia tupiniquim Langer et al. 1999

Holotype

MCP 3844-PV ( Langer et al. 1999, Langer 2003, 2007b) comprising some skull remains, most presacral vertebrae, two primordial sacral vertebrae, several proximal caudal vertebrae, several cervical and trunk ribs, partial scapular girdle and forelimbs, most of the pelvic girdle and hindlimbs .

Paratypes

MCP 3845-PV ( Langer et al. 1999, Langer 2003, 2007b, Bronzati et al. 2017, 2019a, b) is composed of a semi-articulated skeleton, comprising a partial skull with braincase, natural cast of mandibular ramus with teeth, most presacral vertebrae, two primordial sacral vertebrae plus a dorsosacral vertebra, several cervical and trunk ribs, right scapular girdle and forelimb, most of the pelvic girdle and hindlimbs. MCP 3846-PV ( Langer et al. 1999, Bittencourt et al. 2012, Garcia et al. 2019b) is an incomplete skeleton, comprising some presacral and caudal vertebrae and parts of the pelvic girdle and hindlimbs .

Referred specimen UFSM 11660 (A–N)

An association of at least three individuals with different degrees of articulation. It comprises a partial skull with braincase, lower jaws, vertebrae from distinct portions of the column, ribs, chevrons, pelvic girdle, femora, tibiae, metatarsals, and phalanges. Because of its gracile morphology, the specimen was affectionately nicknamed as ‘Gracinha’, meaning graceful in Portuguese. The specific preserved elements are: UFSM 11660A, skull, right maxilla, braincase elements; UFSM 11660B, dorsal vertebrae; UFSM 11660C, sacrum articulated against the ilium, ischium, pubis; UFSM 11660D, partial sacrum; UFSM 11660E, damaged sacrum; UFSM 11660F, proximal caudal vertebrae; UFSM 11660G, articulated caudal vertebrae; UFSM 11660H, caudalmost caudal vertebrae; UFSM 11660I, complete right femora; UFSM 11660J, proximal right femora; UFSM 11660K, proximal portion of a left tibia; UFSM 11660L, right tibia; UFSM 11660M, metatarsus I, II, III and phalange; UFSM 11660N, metatarsus I and II.

Locality and horizon

UFSM 11660 was excavated from the Cerro da Alemoa (= Waldsanga) site ( Langer 2005, Da-Rosa 2015, Garcia et al. 2019a; 29° 41 ʹ 51.0 ʹʹ S, 53° 46 ʹ 26.5 ʹʹ W), in the municipality of Santa Maria ( Fig. 1 View Figure 1 ), which exposes rocks of the Candelária Sequence ( Horn et al. 2014) of the Santa Maria Supersequence ( Zerfass et al. 2003). The outcrop is composed of reddish mudstones, typical of the Alemoa Member of the Santa Maria Formation ( Andreis et al. 1980). The occurrence of the rhynchosaur Hyperodapedon places the site in the Hyperodapedon Assemblage Zone ( Langer et al. 2007a, Schultz et al. 2020). In addition to rhynchosaurs, it yielded dinosaur, silesaurid, lagerpetid, and cynodont remains ( Langer et al. 1999, Martinelli et al. 2017, Garcia et al. 2019a, Marsola et al. 2019, Mestriner et al. 2023). Radioisotopic dating indicates a maximum depositional age of 233.23 ± 0.73 Mya ( Langer et al. 2018).

Ontogenetic remarks

Bones of UFSM 11660 have some osteological indicators of skeletal maturity, such as a raised scar on the lateral surface of the dorsal portion of the iliac blade ( Garcia et al. 2019b) and a proximal portion of the femur with a craniolateral scar, a well-developed trochanteric shelf, and a rounded dorsolateral trochanter ( Piechowski et al. 2014, Griffin and Nesbitt 2016 a, Müller 2022). In addition, all neurocentral sutures are closed ( Brochu 1996, Henrich et al. 2021, but see Irmis 2007). Although the specimens are not skeletally immature, it is uncertain if they reached their maximum size.

DESCRIPTION AND COMPARISONS

The description followed the veterinarian anatomical terms (i.e. ‘cranial’/‘rostral’ and ‘caudal’ are used rather than ‘anterior’ and ‘posterior’), the complete list of specimens used for comparison is in Table 2 View Table 2 and measurements of UFSM 11660 in Table 3 View Table 3 .

Cranial remains

The association includes one skull with articulated to partially articulated elements ( Fig. 2 View Figure 2 ). Hence, the following description of the rostral region, braincase, and partial lower jaws refers to a single individual. The bone surface of the elements is usually well-preserved, but the extremities of some bones are not entirely preserved.

Premaxilla: Both premaxillae are preserved, although slightly displaced from their original position ( Fig. 3 View Figure 3 ). The bone has a convex rostroventral margin and the narial fossa occupies the dorsal half of its main body. The right premaxilla preserved the caudolateral and medial processes, whereas only the dorsal process is present in the left bone. The anterior premaxillary foramen (sensu Sereno et al. 2013) pierces the lateral surface of the bone and an additional, smaller foramen is seen dorsal to that. The rostral tip of the left premaxilla is not preserved, exposing a tooth root. The dorsal process is short and tapers dorsally. Similarly, the caudolateral process is short, as in Pampadromaeus barberenai and Bu. schultzi ( Cabreira et al. 2011, 2016, Müller et al. 2018b). On the other hand, in E. lunensis the process is well developed and elongated, composing the caudal margin of the external nares ( Sereno et al. 2013). The medial process forms a thin blade and is not completely preserved. The displacement of the premaxillae prevents the defining the presence and shape of the subnarial foramen. Unlike Bu. schultzi ( Müller et al. 2018b) , the caudoventral corner of the bone lacks a notch forming a marked gap at the maxilla premaxilla contact. There are at least three teeth preserved in the right premaxilla and although the tooth number cannot be accessed in the left bone, it is possible to see that the first tooth starts in its rostralmost part.

Maxilla: Both maxillae are preserved, but only the left one in its full length ( Figs 3 View Figure 3 , 4 View Figure 4 ). The rostral process is short and its lateral surface bears some foramina. As in Pam. barberenai , two depressed areas excavate the medial surface of the dorsocaudally oriented dorsal process. The longitudinal ridge delimits the ventral margin of the antorbital fossa, which extends along the entire length of the bone. Dorsal to that, six neurovascular foramina pierce the fossa, forming a row parallel to the alveolar margin. Unlike unaysaurids ( Müller et al. 2018c), the rostralmost portion of the antorbital fossa lacks any evidence of a promaxillary fenestra, or of any other excavation. Both internal and external antorbital fenestrae are rostrocaudally elongated. The rounded rostroventral corner of the internal antorbital fenestra forms a straight to slightly obtuse angle ( Fig. 2C View Figure 2 ). The maxillary caudal process is elongated and tapers at the distalmost portion, which has a longitudinally elongated slot on its dorsolateral margin to receive the jugal. The tooth margin is straight along its entire length and bears 19 tooth positions.

Nasal: The specimen preserves the left nasal, which is not completely preserved ( Fig. 2 View Figure 2 ). It corresponds to a thin blade of bone, with a dorsal recess in its lateral side. In dorsal view, the rostral process tapers medially. In lateral view, it projects ventrally to form the dorsal rim of the external nares. The lateral margin of the bone is poorly preserved. As a consequence, it is uncertain if it forms a well-projected shelf, as in other early sauropodomorphs ( Martínez and Alcober 2009, Sereno et al. 2013, Müller et al. 2018a). There is no evidence of crests or ornaments on the dorsal surface of the nasal.

Lacrimal: Only the left lacrimal is preserved. It has an inverted L-shape and contributes to the dorsal and caudal margins of the antorbital fenestra ( Fig. 2 View Figure 2 ). The bone also contributes to the caudal margin of the antorbital fossa, which invades the ventral and anterior processes. The ventral process is slightly longer than the rostral. The lateral margin of the rostral process folds ventrally, forming a ventral crest that extends longitudinally. The lateral surface of the boundary between the rostral and ventral processes is slightly striated. Yet, this region lacks the flange present in Bu. schultzi (CAPPA /UFSM 0035). The ventralmost portion of the ventral process expands caudally, overlapping dorsally the rostral tip of the jugal when in articulation.

Prefrontal: The left prefrontal is disarticulated and preserves the caudal process ( Fig. 2 View Figure 2 ). The preserved dorsal portion is flat. The corner between the dorsal and lateral surfaces is convex in lateral view. The caudal process tappers caudally and is slightly concave in lateral view. Its general morphology resembles that of coeval sauropodomorphs (e.g. Panphagia protos , S. tupiniquim , and Bu. schultzi ).

Frontal: The left frontal is partially preserved and longer than wide. Its ventral surface is exposed, revealing a deep fossa for the olfactory bulb. A laterally concave crest extends along the bone, separating the orbital margin and the cranial fossa, as in S. tupiniquim (MCP 3845-PV) and Pam. barberenai ( Bronzati et al. 2019b, Langer et al. 2019). The crest differs from that of Pan. protos , which is formed by two parallel ridges ( Martínez et al. 2013).

Jugal: The jugal is not entirely preserved ( Fig. 2 View Figure 2 ), lacking the caudal portion. The rostral portion of the bone is elongated and gracile, unlike the taller main body of the bone in herrerasaurs ( Sereno and Novas 1993, Nesbitt et al. 2009, Pacheco et al. 2019). The rostral tip is particularly thin dorsoventrally ( Fig. 4 View Figure 4 ), where it articulates with the maxilla ventrally and dorsally to the lacrimal. The preserved part of the jugal has a smooth lateral surface, a sharp ventrolateral corner, and almost parallel dorsal and ventral margins. The dorsal surface is gently convex on the region that forms the ventral margin of the orbit. On the preserved caudal portion of the bone, there is a dorsal expansion (= dorsal process), which is not entirely preserved.

Braincase: Of the braincase elements, only the basioccipital, parabasisphenoid and prootic ( Fig. 5 View Figure 5 ) are partially exposed. A future contribution will present additional details with the aid of CT-scan data. Forming the caudal portion of the basioccipital, the occipital condyle is kidney shaped, with a more expanded and concave dorsal portion, tapering ventrally in caudal view.

The main body of the parabasisphenoid is preserved, with the basipterygoid process, projecting cranioventrally as in a paratype of S. tupiniquim (MCP 3845-PV; Bronzati et al. 2019a), but not laterally as in Bu. schultzi (CAPPA /UFSM 0035; Müller et al. 2020). The pituitary fossa excavates the rostral surface of the main body of the bone, in the same craniocaudal level of the basipterygoid process. The fossa is relatively short, resembling the condition of Bu. schultzi (CAPPA /UFSM 0035; Müller et al. 2020) and differing from the enlarged fossa of latter sauropodomorphs ( Carabajal 2012). There are two foramina interpreted as the path of the internal carotid foramina, they are in a position similar to that seen in a paratype of S. tupiniquim (MCP 3845-PV; Bronzati et al. 2019a). Dorsally to the parabasisphenoid, the prootic is preserved. Additionally, it is possible to observe the floccular fossa in cross-section.

Dentary: Both dentaries are partially preserved ( Figs 2–4 View Figure 2 View Figure 3 View Figure 4 ). The bone is relatively slender, unlike the robust dentary of latter sauropodomorphs.Thedorsalmarginofitsrostralendisventrally deflected, such as in other early sauropodomorphs (Matínez and Alcober 2009, Sereno et al. 2013, Cabreira et al. 2016, Müller et al. 2018a, Langer et al. 2019). On the contrary, the ventral margin is straight, differing from the ventrally directed margin of taxa like Unaysaurus tolentinoi ( Leal et al. 2004) . The lateral surface of the dentary is pierced by a series of foramina, which starts at the rostralmost portion of the bone and extends caudally as in Pan. protos , Bu. schultzi , and Bagualosaurus agudoensis . In contrast, there is a gap between the first and the next foramen, as in Pam. barberenai . In medial view, the Meckelian groove excavates the ventral portion of the bone, as in Pan. protos . The first alveolus is inset 2.4 mm from the rostralmost end of the bone. The rostralmost teeth are slightly rostrally inclined relative to the alveolar margin. The mandibular symphysis is short, restricted to the rostral end of the dentary. In medial view, it is possible to identify the interdental plates, which are triangular. The posterior portion of both dentaries is poorly preserved.

Dentition: UFSM 11660A bears typical ziphodont teeth, resembling the condition of other early sauropodomorphs, such as E. lunensis ( Sereno et al. 2013) and Bu. schultzi ( Cabreira et al. 2016, Müller et al. 2018a, Moro et al. 2024). The right premaxilla preserves three teeth caudal to an empty tooth position ( Fig. 3 View Figure 3 ). The apicobasal length of the first preserved crown (second premaxillary tooth) is 7 mm. All teeth lack basal constrictions. The second tooth has serrations (eight per millimetre) only in the mesial margin. These are also seen in the distal margin of the 2 nd (CAPPA /UFSM 0244) ( Müller et al. 2018a, Moro et al. 2024) and 3 rd (CAPPA /UFSM 0035) premaxillary teeth of Bu. schultzi , whereas Pam. barberenai has serrations in both carinae of the 4 th and in the distal carina of the 3 rd premaxillary tooth ( Langer et al. 2019). The premaxillary teeth are longer and thinner than those of the maxilla ( Table 3 View Table 3 ).

In the maxilla, UFSM 11660A has at least 19 tooth positions ( Fig. 4 View Figure 4 ), whereas Bu. schultzi has 24, Pam. barberenai has 21, and Ba. agudoensis 23. In labial/lingual views, the mesial margin of the rostral teeth is slightly convex and the distal is almost straight, resulting in a blade-like shape. In more caudal teeth, both margins are slightly convex. The longer tooth crown is 5.5 mm in apicobasal length and the smaller is 2.7 mm. The wider crown is 3.07 mm in mesiodistal width, whereas the smaller is 1.5 mm. The teeth bear ~8 serrations per millimetre. The number of dentary teeth cannot be defined, as the bone is not complete ( Fig. 4 View Figure 4 ). The apical parts of the rostral teeth are broken. The 5 th tooth has the mesial margin convex and the distal one almost straight in labial/lingual views.

Axial remains

The preserved axial elements of UFSM 11660 include at least three dorsal vertebrae, three sets of sacral vertebrae, and 18 caudal vertebrae, only some of them partially articulated. One of the sets of sacral vertebrae is quite damaged, hampering mechanical preparation and, consequently, reliable observations. Due to the impossibility to assign the vertebrae to specific individuals, they are described below simply according to their position on the axial series.

Dorsal vertebrae: UFSM 11660B includes three dorsal vertebrae, two of which in articulation ( Fig. 6 View Figure 6 ). The centra are longer (2.3 mm) than tall (1.4 mm) and lack a ventral keel. Both articular facets are concave and almost as tall as wide. Their parapophysis are located above the centrum, contacting the diapophysis, so the elements are considered as part of the caudal half of the series ( Sereno et al. 2013, Müller et al. 2018a, Langer et al. 2019). Neurocentral sutures are observed in all vertebrae and a slight depression is seen on the lateral surface of their centra. In the neural arches, the diapophyses are dorsolaterally oriented and subretanctangular in dorsal view. The neural spines are caudally inclined and lack any evidence of spine tables. Preand postzigapophyses are broken.

Sacral vertebrae: The two best-preserved sets are composed of two articulated primordial sacral vertebrae. UFSM 11660C is articulated with the ilium and UFSM 11660D is isolated ( Fig. 7 View Figure 7 ). The centra of UFSM 11660D are slightly wider lateromedially and shallower dorsoventrally than those of UFSM 11660C. In UFSM 11660C, the S1 cranial articular surface is concave. In both sets, the S2 caudal articular surface is concave and almost as wide as deep. The sacral centra are not co-osified in both sets and lack ventral keel.

In UFSM 11660C, sacral ribs and transverse processes form a single structure, which connects to the ilium. In UFSM 11660D, in lateral view, the first sacral rib and transverse process form a C-shape, whereas the S2 rib is S-shaped. The neural spines of UFSM 11660C are dorsocaudally inclined, but this might be affected by taphonomy. The prezygapophysis of UFSM 11660C is rounded and projects craniodorsally. In dorsal view of both sets, the transverse processes of S1 and S2 do not contact one another. The S1 transverse process of UFSM 11660D is wider, exhibiting a fan shape. The S2 transverse process is laterocaudally oriented in both sets.

Caudal series: The caudal series is composed of 18 vertebrae ( Fig. 8 View Figure 8 ), including an articulated set of eight mid-caudal vertebrae with chevrons (UFSM 11660G), and ten disarticulated elements, six located proximal (UFSM 11660F) and four distal (UFSM 11660H) to the articulates segment. The centra become longer in the direction to the distal portion of the tail. None of the caudal centra has a ventral keel and both their articular facets are concave. The six proximalmost vertebrae (UFSM 11660F) are axially shortened, with their transverse processes dorsolaterally oriented. The prezygapophysis projects craniodorsally, whereas the postzigapophysis projects caudoventrally. The eight articulated vertebrae (UFSM 11660G) have centra longer than deep, the ventral surface of which lacks a keel. The transverse process is thin and the neural spine is low. The prezygapophysis is craniodorsally inclined, with a rounded and elongated articular facet. The postzygapophysis are rounded. The distalmost vertebrae (UFSM 11660H) are very elongated. These elements are proportionally smaller and do not preserve neural arches.

Pelvic girdle and hindlimb

Ilium: One partial ilium is preserved with sacral vertebrae in the association UFSM 11660C ( Fig. 9 View Figure 9 ). It is almost complete, lacking the preacetabular ala and part of the iliac blade. A disarticulated caudal vertebra is attached to the acetabular wall.

The postacetabular ala is elongated, unlike that of herrerasaurids. There is a conspicuous rugose area on the lateral surface of this structure, identified as the origin of the flexor tibialis externus ( Langer 2003). The brevis shelf delimits the brevis fossa, but does not connect to the supracetabular crest. The supracetabular crest is lateroventrally oriented, its maximum width is at the centre of the acetabulum, and it does not reach the distal end of the pubic peduncle. The acetabular wall of the ilium is not perforated and its ventral margin is straight to slightly concave. The pubic peduncle is cranioventrally directed and its extremity has a subtriangular distal outline. The ischiadic peduncle is ventrally directed. It has an ovoid distal outline and lacks a heel-like projection on the caudal margin.

Pubis: The pair of partially articulated pubis (UFSM 11660C; Fig. 10 View Figure 10 ) are assigned to a single individual. The most complete left bone is 117.38 mm long, with the main axis caudodorsally to cranioventrally oriented. The proximal outline of the iliac peduncle is rounded and the ambiens process forms a raised protuberance on the lateral surface of the main body of the bone. The shaft encompasses a thin medial lamina and its distal end expands dorsoventrally, but not as much as in herrerasaurids or theropods ( Novas 1994).

Ischium: A single left ischium (UFSM 11660C) was preserved. It is c. 100 mm long and almost complete, lacking only part of the obturator plate. Its main body is subtriangular in lateral/ medial views and the shaft is elongated, expanding dorsoventrally at the distal end ( Fig. 11 View Figure 11 ). The main proximal articulation (for the ilium and femur) has an ovoid outline, and the lateral (antitrochanteric) margin is convex, whereas the medial is straight to convex. The angle formed between the dorsal margin of the ischial body and the ischial shaft is more acute in UFSM 11660C, Bu. schultzi (ULBRA-PVT 280), other specimens of S. tupiniquim , and Mbiresaurus raathi , than in Pan. protos .

The antitrochanter is well-expanded laterally, so that its transition to the main body is concave (proximodistally) and well-marked in the lateral surface of the bone. At the dorsal surface of the ischium, a groove extends from near the proximal articulation until the distal end of the bone. Another longitudinal groove extends along the medial surface of the ischial shaft, as also seen in other specimens of S. tupiniquim ( Langer 2003) . A distinct protuberance is seen on the laterodorsal margin of the distal half of the shaft, which is less developed in the other specimens of S. tupiniquim . The distal end expands dorsoventrally and has a convex margin in lateral view. The distal outline of the bone is semi-circular, resembling the condition in Pan. protos .

Femur: There are two right femora in the association ( Fig. 12 View Figure 12 ): one almost complete (UFSM 11660I), 157 mm long, and one preserving only the proximal part (UFSM 11660J), c. 55 mm long as preserved. UFSM 11660I is sigmoid in cranial/caudal and lateral/medial views. Its proximal portion is poorly preserved. The craniomedial tuber is reduced and the craniolateral is connected to a well-developed craniomedial crest (‘cmc’ in Fig. 12 View Figure 12 ) that extends distally along the proximal portion of the bone.

The far better-preserved femoral head of UFSM 11660J has a transverse groove on its proximal surface. The craniolateral tuber is poorly developed and connects to the craniomedial crest (sensu Bittencourt and Kellner 2009), which extends distally along the cranial surface of the bone. The craniomedial tuber is the largest of the femoral head tubers and is separated from the caudomedial tuber by the sulcus for the capitis femoris ligament. Lateral to the caudomedial tuber, the facies articularis antitrochanterica slopes distally.

In both femora the dorsolateral trochanter forms a protuberance located at the level of the femoral head, with its cranial and lateral surfaces covered by striations. The craniolateral scar, located between the dorsolateral trochanter and the craniomedial crest is faint in UFSM 11660J, but well-marked in UFSM 11660I. In UFSM 11660J, the cranial (= lesser) trochanter forms a proximodistally oriented small prominence, the proximal tip of which is completely connected to the shaft. The distal portion of the cranial trochanter is continuous to the femoral cranial intermuscular line, as seen in craniomedial view ( Langer 2003). The trochanteric shelf is set distal to the dorsolateral trochanter and corresponds to a rugose area connected to the cranial trochanter. This part of the femur is fractured in UFSM 11660I, hampering reliable observations of those elements.

Only the proximal tip of the UFSM 11660J fourth trochanter is preserved. In UFSM 11660I, it is located in the caudomedial surface of the bone and merges gently with the shaft proximally. In Bu. schultzi , Mbiresaurus raathi , Pam. barberenai , and other specimens of S. tupiniquim , the distal portion of the fourth trochanter is acute, forming an asymmetrical structure. Instead, in UFSM 11660I, the distal portion of the fourth trochanter merges smoothly to the shaft, forming a symmetrical structure. However, this area is damaged and we interpret it as a taphonomic feature. A fossa for the m. caudofemoralis longus ( Langer 2003) excavates the medial surface of the femoral shaft right cranial to the fourth trochanter.

In cranial view, the distal end of the femur preserves a rugose area towards its lateral portion. The popliteal fossa marks the caudal surface of the distal portion of the bone. Its distal portion is well-delimited, but the proximal portion merges smoothly with the shaft. The distal articulation is composed of three main structures:thelateralandmedialcondylesandthecristatibiofibularis.A distal groove separates the lateral condyle and crista tibiofibularis. The latter is the smallest of the three structures and projects caudally forming a rounded tip. In distal view, the craniomedial margin of the bone is rounded, whereas that of E. lunensis is more projected and almost rectangular.Compared to Mbiresaurus raathi and some specimens of both S. tupiniquim (MCP 3844-PV) and Bu. schultzi (CAPPA /UFSM 0035), the distal end of the femur is more mediolaterally expanded in UFSM 11660I, as in other specimens of the latter taxon (ULBRA-PVT 280).

A fragmentary shaft was associated with the proximal portion of UFSM 11660J. Although they do not perfectly fit, both elements are equivalent in size. The segment is 31.61 mm long, the minimum shaft circumference is 42.97 mm, and the bone wall is 3.98 mm thick. Both caudolateral and cranial intermuscular lines are present and well developed.

Tibia: UFSM 11660 includes a pair of left/right partial tibiae with their proximal portions preserved, but it is not possible to assume that they belong to the same individual ( Fig. 13 View Figure 13 ). The left bone (UFSM 11660K) is better preserved and 71.94 mm long, whereas the right one (UFSM 11660L) is ‘swollen’ and 36.81 mm in length. Their general anatomy resembles that of early sauropodomorphs tibiae, including Pan. protos , E. lunensis , and other specimens of S. tupiniquim .

In proximal view, UFSM 11660K has a subtriangular shape, comprising the cnemial crest, and medial, and lateral condyles. The cnemial crest arcs craniolaterally and is rugose on its cranial surface. The medial condyle is more expanded than the lateral and a cleft/notch is seen between them as in E. lunensis and other specimens of S. tupiniquim . Unlike Bu. schultzi (ULBRA-PVT 280), the medial condyle lacks a caudal projection in UFSM 11660K. The condyles and the cnemial crest are poorly preserved in UFSM 11660L, but the latter is less arched than in the left tibia.

An excavated area for the articulation with the fibula is observed in the lateral surface of both tibiae. In UFSM 11660K it starts at the level of cnemial crest and extends for 17.35 mm distally. A fibular crest extends caudally to its depression, as seen in E. lunensis , Mbiresaurus raathi , and other specimens of S. tupiniquim . There is a rugose area on the medial surface of the tibiae, as observed in many sauropodomorphs (e.g. S. tupiniquim , E. lunensis ).

Metatarsals and phalanges: The preserved pedal parts include two sets of right metatarsals with similar morphology ( Fig. 14 View Figure 14 ). UFSM 11660M is slightly smaller, comprising metatarsals I, II, and III. UFSM 11660N comprises longer metatarsals II (lacking the diaphysis) and III.

The proximal portion of metatarsal I is lateromedially compressed. The bone expands distally, as the shaft arcs medially. This resembles the general morphology seen in the metatarsal I of other S. tupiniquim specimens. Yet, its proximal portion is not ‘L-shaped’ as in Pam. barberenai ( Langer et al. 2019) .

The metatarsal II of UFSM 11660M lacks the proximal portion, but in UFSM 11660N the bone has a subrectangular proximal outline. At the distal end, the medial condyle projects more distally in both specimens. Unlike in Chromogisaurus novasi ( Martínez et al. 2013) , the distal condyles are symmetrical.

The proximal outline of metatarsal III is subtriangular in both individuals, but it is more lateromedially compressed in UFSM 11660M. The outlines resemble those of other specimens of S. tupiniquim , differing from the parallelogram shape outlines of Pan. protos and E. lunensis ( Martinez and Alcober 2009, Sereno et al. 2013). The distal articulation has the medial condyle slightly displaced medially.

Some phalanges are preserved in the association (UFSM 11660M), but it is not possible to assign their position in the pes. A non-terminal phalanx was preserved articulated with an ungual ( Fig. 14 View Figure 14 ). Their morphology resembles that of other early sauropodomorph phalanges. The non-terminal phalanx is longer than wide and presents a constriction at the mid-length. This condition differs from the stouter phalanx of sauropodiforms. Collateral ligament pits excavate the distal condyles. The ungual phalanx is ventrally curved and presents a conspicuous ridge on the lateral surface. It lacks a well-developed tuber on the ventral surface of the proximal portion.