Pagosvenator candelariensis, 2018

PAGOSVENATOR CANDELARIENSIS GEN. ET SP. NOV.

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Etymology: ‘ Pagos ’ is a regional gaucho jargon term (sometimes used in the singular, pago, but its plural use is more common) that is derived from the Latin ‘pagus’, meaning ‘countryside’ or ‘rural community’; ‘ venator ’ is Latin for ‘hunter’ owing to it being a relatively large carnivore; and ‘candelariensis’ is with regard to the city of Candelária, where the museum in which the specimen is deposited is located. The name means ‘the hunter from the surroundings of Candelária’.

Holotype: MMACR PV 036 -T; mostly complete and articulated skull and lower jaws, associated with two incomplete vertebrae and five heavily ornamented osteoderms.

D i a g n o s i s: P s e u d o s u c h i a n (E r p e t o s u c h i d a e) archosaur, with the following unique combination o f ch a r a c t e r s s t a t e s: f o u r p r e m a x i l l a r y t e e t h; maxilla with an edentulous posterior half, large and posteriorly deep antorbital fossa and a posteriorly positioned antorbital fenestra relative t o t h e a n t e r o p o s t e r i o r l e n g t h o f t h e r o s t r u m; ascending process of the jugal bifurcates dorsally into a V-shaped structure that composes the ventral margin of the orbit; lacrimals do not contribute to the skull roof; palpebral bones; slightly longer than wide osteoderms with heavily ornamented dorsal surfaces, displaying small pits and short ridges.

Type locality and age: The locality is unknown (see the previous section and the Supporting Information Appendix S1). The type of preservation of the specimen with a supporting REE analysis indicates that it belongs to a site from the Dinodontosaurus Assemblage Zone, Middle-Late Triassic (late Ladinian–earliest Carnian age), whose outcrops are placed south of the city of Candelária.

DESCRIPTION

Skull overview

The skull of P. candelariensis suffered taphonomic alterations, with the majority of the elements that form the infratemporal fenestra being altered, in the case of the left side, or lost, in the case of the right side ( Fig. 2). The anterior part of the rostrum was damaged and rotated 15° clockwise. The right side of the skull displays major distortions, with many elements, specifically the ones that form the ventral margin of the maxilla, the posteroventral border of the orbit and the infratemporal fenestra, being displaced or lost. Some suture patterns are also distorted, which results in some paired elements not displaying mirrored features.

The premaxilla is formed by a subquadrangular main body, a gracile anterodorsal process and a narrow posterodorsal process. Although both premaxillae are morphologically similar, the right one is distorted and dorsoventrally shorter owing to a heightened ventral curvature. In lateral view, the anterior margin of the main body is sub-vertical, with an anteroventral margin that is recurved up to the remains of the first premaxillary tooth ( Fig. 3). This margin displays a small posterodorsal curvature that ends at the base of the anterodorsal process, which was initially interpreted by Lacerda, França & Schultz (2016) as similar to the condition found in Ornithosuchidae . This posteroventral curvature was extended dorsally because of the compression of the anterior portion of the rostrum, which artificially created an ornithosuchid-like ‘downturned’ condition. The dorsal third of the body of the premaxillae is more medially compressed, forming a marked fossa that forms the anteroventral border of the external naris.

The anterodorsal process is narrow and articulates posterodorsally between two anteroventral projections of the nasals in a V-shaped contact ( Fig. 3), similar to the one described in O. woodwardi ( Walker, 1964) and Riojasuchus tenuisceps (PVL 3827; Bonaparte, 1967; von Bazcko & Desojo, 2016). This area is ventrodorsally compressed, which has altered its dimensions and most of the dorsal border of the naris, which is slightly reduced in height but not overall form. The posterodorsal process of the premaxilla has a wide base that tapers posteriorly, with its most posterior end articulating between two ventral processes of the nasal and ending posterior to the nasal opening. This process is greater than the anteroposterior length of the main body of premaxilla, similar to Gracilisuchidae and early branch loricatans and different from the comparatively smaller process in E. granti (NHMUK R3139), Ornithosuchidae (NHMUK PV R3143; PVL 3827) and Aetosauria (e.g. SMNS 5770) ( Nesbitt, 2011; Nesbitt & Butler, 2012). The posterodorsal process is better observed in dorsal view, because in lateral view, owing to the above-mentioned alteration of this region of the skull, it appears as a smaller, acute process. Its distal end fits into a slot in the nasal, similar to Revueltosaurus callenderi ( Hunt, 1989; Parker et al., 2005) and Gracilisuchidae ( Butler et al., 2014) .

Tooth remains are preserved on the anterolateral and ventral portions of the rostrum, but only the two on the left premaxilla are preserved in their sockets, with the most posterior one being the better preserved. The above-mentioned alteration in the ventral curvature damaged most of the area, and its remains were preserved in a large concretion mixed with bone and tooth fragments that obscures most of this area. The number of alveoli was determined only by CT scans, which revealed four in each premaxilla ( Fig. 4). The number of premaxillary teeth is variable in pseudosuchians. Four teeth are in E. granti (NHMUK R3139), Aetosaurus ferratus (SMNS 5770; Schoch, 2007), Gracilisuchus stipanicicorum Romer, 1972 ( Butler et al., 2014) and early branch taxa of Loricata, whereas some taxa, such as Stagonolepis robertsoni Agassiz, 1844 , Revueltosaurus callenderi , Turfanosuchus dabanensis Wu, Lui & Li, 2001 and Yonghesuchus sangbiensis Wu & Russell, 2001 bear five teeth, and O. woodwardi and R. tenuisceps have three teeth in the premaxilla ( Walker, 1961, Nesbitt, 2011; Nesbitt & Butler, 2012).

The maxilla is divided in a subrectangular main body and a dorsoventrally tall and anteroposteriorly wide ascending process. The anterior portion, which articulates with the premaxilla, in dorsal view has a marked transverse expansion, which is mirrored in both maxillae, a condition that is uncommon in archosaurs but is described in P. gracilis (NHMUK R8646; Nesbitt & Butler, 2012). In lateral view, the main body is dorsoventrally expanded, and both anterior and posterior areas display similar dorsoventral depths. The premaxilla–maxilla suture is tightly closed, not displaying any foramina or accessory openings, and not displaying a diastema between the elements, unlike Ornithosuchidae (NHMUK PV R3143; PVL 3827). The anterior margin is rounded, slopping posterodorsally into the anteroposteriorly elongated ascending process. This process articulates posteriorly between the nasal and posteroventrally with the anterodorsal and anterior margins of the lacrimal. The posterior portion forms the majority of the anterior margin of the antorbital fenestra. The anterior portion of the ventral margin is straight, up to the area where the rostrum is damaged. From there, it is slightly concave, and the ventral area with the alveoli is more laterally projected. This projection was probably caused by taphonomic compression. On the posterior end of this margin, there is a small posteroventral process that extends 8 mm beyond the articulation with the jugal. The posterior process of the maxilla has almost the same dorsoventral height on the posterior region, not tapering as in Ornithosuchidae (NHMUK PV R3143; PVL 3827) or expanding as in E. granti (NHMUK R3139) and P. gracilis (NHMUK PV R8646) ( Nesbitt & Butler, 2012). However, the mediolateral length is greater than the dorsoventral height on the level of the main body of the lacrimal, a characteristic shared with E. granti and P. gracilis ( Nesbitt & Butler, 2012) .

The antorbital fossa occupies most of the lateral surface of the maxilla. This fossa gradually deepens posteriorly, reaching its deepest point close to the ventral area of the lacrimal and the anterior margin of the jugal. The antorbital fenestra is half the anteroposterior length of the fossa and is posteriorly located on the rostrum. It is subtriangular but very dorsoventrally compressed, almost to the point of a slit, with a rounded anterior tip, and displays a 25° dorsoventral inclination with regard to the central axis of the maxilla. The nearly pointed anterior margin of the antorbital fenestra is shared with Erpetosuchus and some ornithosuchid taxa ( Venaticosuchus rusconi and R. tenuisceps ), but a gently rounded anterior margin is observed in O. woodwardi ( Nesbitt & Butler, 2012; von Baczko et al., 2014; von Baczko & Desojo, 2016; von Baczko & Ezcurra, 2016).

Owing to the lateral distortion of the ventral margin of the left maxilla, the posterior third of this element is turned laterally, exposing the ventral margin, with five concretion-filled alveoli and an edentulous posterior region after the last alveolus. Computer imaging identified teeth starting immediately posterior to the articulation with the premaxilla, so at least six maxillary teeth would be present. With the exception of archosaurs that have a more specialized maxilla for herbivory (e.g. poposaurids), an edentulous posterior region of the maxilla is described only in Erpetosuchidae ( Nesbitt, 2011; Nesbitt & Butler, 2012). However, this would differ from P. gracilis , which has only five, and E. granti , which has four, but is similar to the possible nine maxillary teeth inferred for a specimen attributed to Erpetosuchus sp. (AMNH 29300; Olsen, Sues & Norell, 2000).

All teeth are badly preserved, being incomplete or covered in a thick layer of concretion. The two largest teeth are on the ventral border of the right maxilla, and three disarticulated teeth are preserved along the underlying lateral face of the left mandible. The teeth are anteroposteriorly recurved and lateromedially compressed, and there is no indication of any serrations ( Fig. 3).

The nasals are anteroposteriorly elongated elements that form the majority of the anterodorsal and dorsolateral surface of the rostrum, with both elements articulating medially. The dorsal surface is smooth and continues the length of the skull roof, with no indication of a convexity or ‘roman nose’-like feature as in Decuriasuchus quartacolonia (MCN PV10.105a; França et al., 2011; França, Langer & Ferigolo, 2013). The anterior portion, in lateral view, is anteroventrally curved and divided into two processes. The anteroventral process forms the majority of the dorsal and posterodorsal border of the external naris and contacts the dorsal tip of the anterodorsal process of the premaxilla, and it extends laterally and anteroventrally up to half its length. The posteroventral process is comparatively short and narrow. It articulates with the posterodorsal process of the premaxilla, forming a depressed area for this contact, with a piece of the process occupying an area between the premaxilla and maxilla. The main body of the nasal forms the anterior portion of the skull roof, with a broad mediolateral length, whereas the posterior process is located on its medial half and posteriorly tapering along the articulation with the frontal. The nasal has a broad contact with the prefrontal, on the posterior margin of the main body and the anterolateral region of the posterior process, unlike in Ornithosuchidae , where these bones do not meet ( Walker, 1964; von Baczko & Ezcurra, 2013; von Bazcko & Desojo, 2016). In addition, Pagosvenator does not share with the Gracilisuchidae and some loricatans (e.g. Rauisuchidae ) the nasal contribution to the antorbital fossa ( Nesbitt, 2011; França et al., 2013; Butler et al., 2014).

The lacrimal is divided into two processes; an anterior L-shaped process that is anteroposteriorly inclined, and a posteroventral process that forms three-quarters of the anterior margin of the orbit ( Fig. 3). This bone is completely covered dorsally, lacking any contribution to the skull roof. The anterior process delimits the posterior half of the dorsal and all the posterodorsal margins of the antorbital fossa, along with the posterodorsal margin of the antorbital fenestra. It forms, with the prefrontal and the jugal, a thick anterolateral expansion or ridge along the extent of the antorbital bar. This ridge forms a deep pocket on the posterodorsal end of the fossa, similar to the one in R. tenuisceps , some theropods and basal saurischians ( Nesbitt, 2011; von Bazcko & Desojo, 2016 but it displays a more lateral expression, although this may have been artificially deepened as a result of the distortion already described.

The prefrontal is a wide element of the skull roof, with a discrete presence on the lateral view ( Figs 2, 3). It articulates anteromedially with the nasals, posteromedially with the frontal and ventromedially with the jugal, forming most of the anterior border of the orbit. Its anterior portion is not in articulation with the rostrum anteriorly, owing to the distortion that this part of the skull suffered, which is indicated by a transverse fracture on the anterior portion of both prefrontals, but would indicate the overall aspect of the anterior margins. In dorsal view, it is subrectangular, with a straight anterior margin, a convex posterior margin and a small lateral process that covers the lacrimal ventrolaterally. The dorsal surface displays a deep fossa that is mirrored on both elements. This fossa is lateral to the anterior processes of the frontal and is near an area that displays a large number of fossae and ridges that appear not to be formed by taphonomic alterations, which would indicate a heavily ornamented region of the skull roof. The lateroventral process, along with the posterodorsal region of the lacrimal, forms a bar that delimits posterodorsally the deepest part of the antorbital fossa.

The frontal is a wide, dorsoventrally compressed element that articulates anteriorly with the nasals by two narrowing anterior processes, anterolaterally with the prefrontal along a sinuous contact, posterolaterally with the postorbital and posteriorly with the parietal along a lateromedially wide U-shaped process ( Fig. 3). In anterior view, the lateral portion near the orbits displays a marked dorsal curvature, and its surface is marked by deep pits and ridges that are mirrored on both sides of the element and continue up to the palpebrals. The frontal makes up the dorsal border of the orbit and articulates lateroposteriorly with a palpebral element, which is better observed on its right side. The presence of a single frontal and the rare pattern of the nasal–frontal suture in archosaurs matches the condition described for E. granti ( Benton & Walker, 2002) , but in P. candelariensis this region of the skull roof is more lateromedially wide, whereas in the former it is more constrained. No longitudinal ridge along the midline or the anterior portion tapering anteriorly is observed in P. candelariensis , differing from Gracilisuchidae and some early branch loricatans in that these features are present ( Nesbitt, 2011; Nesbitt & Butler, 2012).

The right palpebral is mostly preserved, with the left one represented only by its medial portion that is still in articulation with the other elements on the dorsal margin of the orbit along a large fracture. Most of this damaged area corresponds to that which is occupied on the left side by the other palpebral and the dorsal portion of the postorbital. Additionally, the palpebral articulates posteromedially with the postfrontal and posteriorly with the postorbital. In dorsal view ( Fig. 3), its shape is subrectangular, with a thick and rugose lateral margin, whereas the dorsal surface displays a series of pits and the lateral continuation of some ridges that arise on the frontal. The presence of a palpebral element is described in aetosaurs, loricatans, poposaurids, crocodylomorphs and ornithischians, with its overall morphology varying greatly between different groups, within the same taxon and during ontogeny ( Nesbitt, Turner & Weinbaum, 2013b) but the palpebrals of the described specimen appear distinct, because no sub-rectangular element, in dorsal view, with shallow pits has been described.

The postfrontal, in dorsal view, is an irregular bone that articulates anterolaterally with the palpebral, anteriorly and anteromedially with the frontal, posteromedially with the parietal and posterolaterally with the postorbital. As such, it does not participate in the margin of the orbits, but its convex posterior margin forms most of the anterior border of the supratemporal fenestra. Its overall irregular form, in dorsal aspect, differs from that of most of the postfrontals described in basal suchians, but its participation in the skull roof, with its posterior border forming the anterior margin of the supratemporal fenestra region, is similar to the ones in Riojasuchus (PVL 3827; von Baczko & Desojo, 2016).

The left postorbital is mostly preserved and divided into an incomplete dorsal portion and a ventral portion, whereas the right postorbital is represented by only a fragment of the anterior portion. In dorsal view, it is anteroposteriorlly elongated, with its anterior region being mediolaterally expanded with a short mediolateral process. This anterior region articulates with the lateral margin of the postfrontal, and its main body forms the lateral margin of the supratemporal fenestra, which ends in a narrow posterior process that is turned lateromedially up until its broken tip. The anterior contact of the ventral portion articulates along the damaged area of the palpebral, whereas its main body projects anteroventrally and forms the posterodorsal and posterior border of the orbit. The posterior process that contacts the squamosal is mostly restricted dorsally, unlike aetosaurs, Gracilisuchus and Yonghesuchus , where it is ventrally broad. The ventral process of the postorbital in Pagosvenator is similar in length to the jugal in the composition of the postorbital bar.

Only the left squamosal is preserved, and it is divided into two segments ( Figs 2, 3). The first is anteriorly displaced and is ventrally displaced to the dorsal portion of the postorbital. It displays an anteroposteriorly wide dorsal section that has on its anterodorsal surface a shallow fossa for the articulation of the posterior portion of the postorbital and an anteroposteriorly curved ventral process that contacts the postorbital ramus of the ascending process of the jugal, near the articulation of this element with the ventral process of the postorbital. Owing to the damage suffered by the posterior region of the skull, it is twisted 30° anticlockwise and displaced more anteriorly, between the anterior and posterior ramus of the posterior process of the jugal. As a result of this distortion, it occupies an area equivalent to the infratemporal and exposes only two small lateral openings. The second piece is a small fragment of the posteromedial region that is positioned more posteriorly and is in articulation with the paraoccipital process of the braincase. The dorsal surface of the squamosal on the supratemporal fenestrae is smooth, without any ridges or marked edges. The ventral process lacks the lateral ridge or the anteroventral projection found in some loricatans, such as Saurosuchus galilei (PVSJ 32; Alcober, 2000) and Prestosuchus chiniquensis (UFRGS-PV-0156-T; Barberena, 1978; Azevedo, 1991).

The parietal is a single element, with no indication of a parasagittal suture, similar to the condition of the frontal ( Fig. 5). In dorsal view, its main body is subrectangular and dorsoventrally flat, with an anterior portion formed by two anterolateral processes that form, anteriorly, a sub-circular contact with the frontal and articulate anterolaterally with the postfrontals. Two elongated, anterolaterally compressed, posterolateral processes are present, projecting from the posterior half of the main body, and form occipital flanges, similar to O. woodwardi (NHUMK R2409; Walker, 1964). However, this process is nearly vertical, whereas in Ornithosuchidae and aetosaurs this process is> 45° inclined anteriorly. The left one is preserved, but the right has been damaged, preserving only the fragments closer to the contact with the occipital. The presence of a single parietal is uncommon in archosauriforms, being described in Erpetosuchus and in some crocodylomorphs. However, as observed in the modern taxa of the latter group, the parietal can arise as two separate elements and fuse during late ontogeny ( Rieppel, 1993), although it is impossible to infer whether this was the case in the present specimen.

The jugal is a triradiated element, divided into a main body, with anterior, dorsal and posterior processes. The posterior process is broken into two segments owinng to the collapse of the area of the infratemporal fenestra and disarray of the quadratojugal–jugal articulation. The anterior process is anteroposteriorly short and articulates with the main body of the maxilla, forming the posterior rim of the antorbital fossa and the posterior margin of the antorbital fenestra, a condition that is also described in Proterosuchus fergusi , some proterochampsids, phytosaurs, ornithosuchids, sauropodomorphs and ornithischians ( Nesbitt, 2011; von Baczko & Desojo, 2016; Ezcurra, 2016). However, the closest match is the one described in Erpetosuchus ( Benton & Walker, 2002) , which displays a jugal with five processes, but with its two anterior processes forming a posterior limit to a deep antorbital fossa, which is morphologically the closest to the one in Pagosvenator .

The dorsal process is divided into preorbital and postorbital rami, which form the ventral margin of the orbit and have a distinct V-shaped aspect in lateral view, like the one described in Erpetosuchus ( Benton & Walker, 2002) and in ornithosuchids, but is ventrally more rounded like the one in the Riojasuchus , compared with the more acute one in Ornithosuchus ( von Baczko & Desojo, 2016) . The preorbital ramus articulates with the lacrimal along a broad vertical suture, whereas the postorbital ramus contacts the postorbital bone.

A large area of damage is present on the lateral portion of the main body and on most of the posterior process. A longitudinal ridge is present on the lateral surface of main body of the jugal in Pagosvenator , although it does not display a bulbous appearance, such as those in rauisuchids (e.g. Gower, 1999; Lautenschlager & Rauhut, 2014). The posterior process is broken into two segments; its anterior part is wedge shaped in lateral view and positioned more posteroventrally, whereas the posterior portion is preserved in articulation with the quadratojugal on the dorsal margin of the mandible. This articulation is similar to the one in Riojasuchus and Ornithosuchus ( Walker, 1964; von Bazcko & Desojo, 2016), but taphonomic alterations have twisted this area dorsolaterally, displaying the ventral area where the quadratojugal articulates with the jugal along a wide, rounded contact. The posterior process is dorsal to the quadratojugal on this contact, with posterior limits anterior to the posterior margin of lower temporal fenestra, unlike Erpetosuchus , Gracilisuchus and Yonghesuchus in that the process is located posterior to the fenestra.

The elements of the posterolateral regions of the skull have suffered major displacement, whereas most of the elements of the right side have been lost. The quadratojugal is represented by only the posterior portion of the left element, with only its posterior half visible owing to the swivel of the ventral bar of the infratemporal fenestra. In dorsal view, it is an anteroposteriorly wide, subrectangular bone, with a sinuous lateral margin and a mediolaterally broad posterior region, which has a small fracture on its lateral margin. In lateral view, it articulates with the posterior process of the jugal along an anteriorly directing V-shaped suture and medially with the posterior region of the quadrate. Despite the taphonomic bias, the quadratojugal is not dorsally expanded, occupying <80% of the posterior border of the lower temporal fenestra, unlike Erpetosuchus , Gracilisuchidae and aetosaurs.

The quadrate is an anteroposteriorly elongated bone which, owing to the disarticulation of the posterior elements of the skull, is more anteriorly located, where its anterior portion is positioned lateral to the braincase and twisted dorsally ( Fig. 3). It articulates laterally with the quadratojugal, with a small foramen between the two elements in its central portion. Its posterior tip is mediolaterally expanded along a straight margin of the articular condyle.

The right lateral and ventral portion of the occipital region is covered by concretions and osteoderm fragments, also obscuring most elements of this side of the skull and completely covering the foramen magnum ( Fig. 6). The supraoccipital, in posterior view, is a dorsoventrally short but lateromedially wide subtriangular element. It articulates dorsally with the parietal along its posterolateral processes, ventrolaterally with the opisthotic and ventrally with the exoccipitals. The dorsal surface of its main body is smooth, with no indication of a ridge or process. Only the proximal portion of the opisthotic is preserved, with a reduced posterolaterally projecting paraoccipital process that ends on a fragment of a medial portion of the squamosal. Owing to an accumulation of osteoderms on the right side of the ventral portion of the supraoccipital, only the left exoccipital is visible. It is a small, quadrangular element in posterior view, which is tightly fused anteriorly with the supraoccipital and anterolaterally with the opisthotic.

Mandibles

Both mandibles are present but not in articulation with the skull, being positioned under and roughly inside the mouth cavity. This placement made it impossible to visualize the tooth-bearing dorsal margin of the mandibles, and CT scans proved unreliable to provide useful information. The anterior tips of the mandibles were fractured along with the rest of the rostrum and also dislocated, with the right piece being displaced more medially and the left one more laterally, covering the region posterior to where the fracture occurred ( Fig. 4). The left mandible is twisted, with its lateral face placed dorsolaterally, whereas only the ventral portion of the right mandible is visible outside the mouth cavity. Owing to these alterations, all of the medial regions of the mandibles, with the exception of the posteriormost region of the left one, are impossible to observe.

Although mostly covered by the skull and distorted, the presence of a mandibular fenestra is not clear, but this is because the posterior portion of the left mandible is covered by the jugal and associated unidentified bone fragments, although the shape of mandibular bones (posterior end of dentary; anterior end of surangular and angular) indicate its presence, but its exact appearance and dimensions are impossible to establish.

The dorsoventral height of the dentary is unknown owing to the obstruction of the dorsal margin. Its visible surface, ventral to the posterior area of the maxilla, indicates a dorsoventrally expanded and anteroposteriorly elongated element, which is dorsoventrally reduced anteriorly with a smooth, rounded ventral margin of the anterior tip of the mandible. Its posterodorsal margin has a short dorsal process that meets a concretion that is also at the ventral base of the squamosal, posterolaterally with the surangular and posteroventrally with the angular.

The surangular is a mediolaterally compressed element that displays a dorsoventrally short anterior portion that expands posteriorly up to two-thirds of its length. It extends posteriorly, forming the majority of the posterior portion of the mandible, and almost completely excludes the articular in lateral view. This condition where the surangular completely obscures the articular laterally is similar to the one described in the loricatan Batrachotomus kupferzellensis ( Gower, 1999) , the paracrocodylomorph Postosuchus kirkpatricki ( Weinbaum, 2011) and in Erpetosuchus ( Benton & Walker, 2002) , but in the latter taxon this must be considered with reservations because it is inferred based on casts that might not preserve more delicate sutures. It displays a sharp lateral shelf formeds along the anteroposterior length of its dorsal surface, with an underlaying fossa that runs ventral to the shelf.

In dorsal view, the articular is a triangular element that articulates laterally with the surangular, which excludes it almost entirely from the lateral portion of the hemimandible. Its anterior portion presents an anteroposteriorly wide, concave glenoid fossa, which is covered in a thick concretion, but lacks any transverse ridge, aside from a small dorsal projection on the end of its medial portion. The medial process is present and robust, but does not present any foramen as in the Batrachotomus and Decuriasuchus ( Gower, 1999; França et al., 2013). The retroarticular region displays an angled posterior process, with a longitudinal ridge that extends the posterior margin of this element dorsoventrally. Owing to the preservation of the medial portion of the mandible, it is impossible to interpret the form and sutures of the prearticular and coronoid bones.

A number of unidentified fragments are observed on the left side of skull. The most anterior one is elongated, narrow and is positioned on the posterior region of the dentary. The second one covers the lateral side of angular, with a semicircular posterior region and a broken anterior facet. Considering the anatomical position, both bones could be skull fragments, but their poor preservation prevents a clear identification.

Postcranial elements

The remains of two articulated vertebrae lying on their right sides were preserved behind the occipital region of the skull ( Fig. 5). One vertebra is represented only by its neural spine and left postzygapophysis, whereas the second has a complete sub-rectangular vertebral body and ventral portion of the neural arch, with the left prezygapophysis in articulation with the corresponding postzygapophysis of the adjacent preserved vertebra.

Six osteoderms are associated with the specimen ( Figs 5, 6). Two are complete and four incomplete, with the largest and best-preserved one being rectangular (32 mm anteroposterior length and 33 mm lateromedial width). The borders are smooth, lacking an anterior process similar to the ones in aetosaurs ( Nesbitt & Butler, 2012; Desojo et al., 2013) and the doswellidae Archeopelta arborensis (CPEZ-239a; Desojo et al., 2011) ( Fig. 7). All osteoderms are heavily ornamented, with a dorsal surface covered with small pits and short ridges, but lacking a central anteroposteriorly extended ridge like the one in Erpetosuchus and Parringtonia ( Nesbitt & Butler, 2012) . Owing to the disarticulated condition of the postcranial elements, it is unclear how the osteoderms where arranged when in articulation and which section of the cervical sequence they would belong to, even though they were preserved near the skull. However, the lengths of the osteoderms are consistent with two anteroposterior segments per vertebra, probably with a paired sagittal axis.

PHYLOGENETIC ANALYSIS

The new taxon, P. candelariensis , was included in a matrix with 418 characters and 85 terminal taxa. The matrix is based on the original analysis of Nesbitt (2011), with compilations of its modified versions by Butler et al. (2011), Nesbitt & Butler (2012), Butler et al. (2014) and von Baczcko et al. (2014). Additionally, one new character is proposed, and some characters states were altered, using information based on personal study of specimens and on recently articles (full details in the Supporting Information, Appendix S2). The matrix was analysed in TNT ( Goloboff, Farris & Nixon, 2008), using a heuristic search with 10 000 replicates of Wagner trees, tree bisection and reconnection (TBR) branch swapping (holding 10 trees per replicate), with collapsed branch with zero length. Some multistate characters were ordered according to parameters stated in the original analysis and above-mentioned works: 32, 52, 121, 137, 139, 156, 168, 188, 223, 247, 258, 269, 271, 291, 297, 328, 356, 377, 399, 198, 416. Bootstrap and Bremer support were calculated with scripts on TNT. Additional analyses in searching for unstable taxa were conducted in TNT, using the IterPCR script proposed by Pol & Escapa (2009).

The cladistic analysis resulted in 360 most parsimonious trees, with 1358 steps. Pagosvenator candelariensis was found to be a sister group of E. granti plus P. gracilis , composing the earliest diverging branch of Erpetosuchidae ( Fig. 8).

In previous analyses, this group had been considered as an unstable taxa ( Nesbitt & Butler, 2012), with six possible positions: (1) earliest branch from Pseudosuchia; (2) earliest branch from Suchia (including G. stipanicicorum , T. dabanensis, Aetosauria, Paracrocodylomorpha and other related taxa); (3) sister group of T. dabanensis (not found as sister group of G. stipanicicorum in this analysis); (4) earliest branch of the Aetosauria lineage, being a sister group of the clade composed of Revueltosaurus plus Aetosauria; (5) earliest branch of the Paracrocodylomorpha lineage, being a sister group of the clade composed by Ticinosuchus ferox ( Krebs, 1965) plus Paracrocodylomopha; and (6) earliest branch of Avemetatarsalia ( Fig. 1C). Butler et al. (2014) considered Erpetosuchidae as a wild taxon, also revealing this unstable position in the evolution of Archosauria, with the consensus tree from this analysis being poorly resolved and displaying a major polytomy at the base of Archosauria.

In the present analysis, the strict consensus (see Supporting Information, Appendix S1, S2) reveals a similar topology. However, there is a polytomy at the base of the pseudosuchian lineage, formed by Erpetosuchidae , Ornithosuchidae , the clade composed by Revueltosaurus plus Aetosauria, and the clade composed by Gracilisuchidae plus T. ferox and Paracrocodylomorpha.Accordingly,the alternative positions of Erpetosuchidae as a sister group of T. dabanensis or an early branch of Paracrocodylomorpha or an early branch of Avemetatarsalia were not supported with this analysis. Furthermore, the result of unstable taxa analysis ( Pol & Escapa, 2009) excluded the alternative position of Erpetosuchidae as an early branch of Pseudosuchia or an early branch of the Aetosauria lineage (sister group of Revueltosaurus plus Aetosauria). The results of the analysis reveal, before one iteration, only two possible positions of Erpetosuchidae among the most parsimonious trees: as a sister group of Ornithosuchidae , composing an early branch lineage of Pseudosuchia, or a sister group of the clade composed of a polytomy among Gracilisuchidae , T. ferox plus Paracrocodylomorpha. A brief consideration of this latter clade is needed. Nesbitt (2011) considered Ticinosuchus to be a sister group of Pararocodylomorpha, a clade composed by Poposauroidea (including Qianosuchus mixtus , Poposaurus gracilis , Shuvosaurus inexpectus and their related taxa) plus Loricata (including P. chiniquensis , S. galilei , Rauisuchidae, Crocodylomorpha and related taxa). Paracrocodylomorpha is phylogenetically defined as a node-based clade composed of the least inclusive clade containing Poposaurus and Crocodylus niloticus Laurenti, 1768 ( Nesbitt, 2011). In this sense, Paracrocodylomorpha is revealed in the present analysis, although it would not be accurate if Ticinosuchus belongs to this group or if it is the sister group. Likewise, it is important to consider that other phylogenetic analyses support Phytosauria as an early branch on Pseudosuchia (e.g. Brusatte et al. 2010; Ezcurra, 2016), contrasting with the analysis of Nesbitt (2011) and probably influencing the relative topology on Pseudosuchia with polarization/optimization of character states among transformational series.

When constraint among Erpetosuchidae and Ornithosuchidae was forced, it resulted in 180 most parsimonious trees, with zero Bremer support. The only controversial synapomorphy for this clade is the presence of anteroposteriorly longer than wide dorsal presacral osteoderms, shared by P. candelariensis , E. granti (NHMUK R3139R) and O. woodwardia (HHMUK R2410) , whereas the osteoderms of Parringtonia (NHMUK R8646) are squared, those in R. tenuisceps (PVL 3827) are wider than long, and none in V. rusconii ( Bonaparte, 1972; von Baczko et al., 2014) is preserved (character 407).A previous preliminary analysis of P. candelariensis ( Lacerda et al., 2016) , proposed it as an early branch of Ornithosuchidae . However, this analysis did not incorporate E. granti and P. gracilis , and some character states were modified with a more accurate revision of the anatomy, as well as CT scan analysis (e.g. the relative inclination between premaxilla and maxilla is not sustainable; the number of premaxillary teeth and number and position of the maxillary ones was revealed only by means of X-ray images).

The alternative position of Erpetosuchidae , as a sister group of a clade composed by Gracilisuchidae and Paracrocodylomorpha plus Ticinosuchus , also has zero Bremer support. However, the clade composed by Erpetosuchidae plus Paracrocodylomorpha is supported by two synapomophies: presence of ventromedial process on the articular (character 157), being reversed to absence on G. stipanicicorum ( Romer, 1972; Butler et al., 2014) and some Poposauroidea ( Nesbitt, 2011) ( S. inexpectus , Effigia okeeffeae and Lotosaurus adentus ); and the scapula bearing a teardrop-shaped tuber on the posterior edge for attachment of m. triceps (character 219), being reversed on P. kirkpatricki ( Chatterjee, 1985; Weinbaum, 2013), Crocodylomorpha and Loricata ( Nesbitt, 2011), whereas in P. candelariensis this character is placed as missing data because this bone was not preserved.

The Erpetosuchidae clade displays a low support, with a Bremer value of one and Bootstrap at 64. Two synapomorphies support this clade and are found in all three members: maxillary teeth only present on the anterior region of bone (character 17), being present in only O. woodwardi (NHMUK R2409, R3143); and maxillary region ventral to the lacrimal has a mediolateral height greater than its dorsoventral length (character 21), converging with only L. adentus and E. okeeffeae . In addition, two synapomorphies support a closer relationship among E. granti and P. gracilis : absence of tooth serration (character 168); and a longitudinal bend on the dorsal presacral osteoderms (character 404), also converging with Euparkeria capensis (SAM PK5867, 6047, 6049), Gracilisuchidae ( Butler et al., 2014) , B. kupferzellensis (SMNS MHI 1895) ; Fasolasuchus tenax (PVL 3850); Rauisuchidae (BSPG AS XXV 92, 97; Chatterjee, 1985; Weinbaum, 2013) and several crocodylomorphs ( Nesbitt, 2011).