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1 Historical Biology An International Journal of Paleobiology ISSN: (Print) (Online) Journal homepage: A capitosauroid from the Lower Triassic of South America (Sanga do Cabral Supersequence: Paraná Basin), its phylogenetic relationships and biostratigraphic implications Estevan Eltink, Átila A. Stock Da-Rosa & Sérgio Dias-da-Silva To cite this article: Estevan Eltink, Átila A. Stock Da-Rosa & Sérgio Dias-da-Silva (2016): A capitosauroid from the Lower Triassic of South America (Sanga do Cabral Supersequence: Paraná Basin), its phylogenetic relationships and biostratigraphic implications, Historical Biology, DOI: / To link to this article: Published online: 15 Nov Submit your article to this journal View related articles View Crossmark data Full Terms & Conditions of access and use can be found at Download by: [ ] Date: 16 November 2016, At: 14:24

2 Historical Biology, A capitosauroid from the Lower Triassic of South America (Sanga do Cabral Supersequence: Paraná Basin), its phylogenetic relationships and biostratigraphic implications Estevan Eltink a, Átila A. Stock Da-Rosa b and Sérgio Dias-da-Silva c a Colegiado de Ecologia, Universidade Federal do Vale do São Francisco, Senhor do Bonfim, Brazil; b Laboratório de Estratigrafia e Paleobiologia, Departamento de Geociências, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, Brazil; c Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Universidade Federal de Santa Maria, São João do Polesine, Brazil ABSTRACT Surviving through the end-permian mass extinction, stereospondyls reemerged reaching a widespread distribution during the Early Triassic. A well representative lineage of this clade, Capitosauroidea, became worldwide abundant from Early to Late Triassic, in which their first undoubtful representatives were recovered from Lower Triassic deposits. Here, we describe a new capitosauroid, Tomeia witecki gen. et sp. nov., from the Sanga do Cabral Supersequence (Paraná Basin). Although relatively incomplete, the material presents a particular combination of early and late-diverging capitosauroid characters. Supporting Tomeia witecki as a new capitosauroid, our phylogenetic analysis placed the taxon as part of a clade that comprises only Early Triassic capitosauroids, specifically as the sister-taxon of the madagascarian Edingerella madagascariensis and close to Watsonisuchus spp., from Australia, South Africa and Madagascar. The status of Tomeia witecki as a new capitosauroid from western Gondwana supports a continuous record of the Stereospondyl lineage, since their first appearance during the Middle Permian in this supercontinent. Additionally, the temporal range of the Sanga do Cabral Supersequence during the Early Triassic was specifically reinforced as Olenekian, mainly based on the overall faunal content previously reported to this unit, associated with the known temporal distribution from those taxa phylogenetically closer to Tomeia witecki. ARTICLE HISTORY Received 11 May 2016 Accepted 28 October 2016 KEYWORDS Temnospondyli; Capitosauria; Early Triassic; Sanga do Cabral Supersequence; South America; Gondwana Introduction In South America, the knowledge about Permian temnospondyls comes from two units, the Paraná and Parnaíba Basins. The former bears the Rio do Rasto Formation, which already yielded the archegosauroid Bageherpeton longignathus (Dias & Barberena 2001), the konzhukoviid Konzhukovia sangabrielensis (Pacheco et al. 2016), the rhinesuchid Australerpeton cosgriffi (Barberena 1998; Dias & Richter 2002; Dias & Schultz 2003; Eltink & Langer 2014; Eltink et al. 2016) and a still unnamed short-snouted rhinesuchid (Barberena & Dias 1998). The Parnaiba basin bears the firstly discovered temnospondyl from South America, Prionosuchus plummeri (Price 1948; Cox & Hutchinson 1991), and also Procuhy nazariensis and Timonya anneae, both from the Early Permian Pedra do Fogo Formation (Cisneros et al. 2015). South American Lower Triassic strata include the rhytidosteid Sangaia lavinai (Dias-Da-Silva & Marsicano 2006; Dias-Da-Silva et al. 2006) and a plagiosternine plagiosaurid (Dias-Da-Silva & Milner 2010), from the Sanga do Cabral Supersequence (Paraná Basin), and the Uruguayan Uruyiella liminea and Arachana nigra, and mandibular elements tentatively ascribed to capitosauroids from the Buena Vista Formation (Paraná Basin) (Piñeiro, Marsicano & Damiani 2007, Piñeiro, Marsicano & Lorenzo 2007; Piñeiro et al. 2012). From the Upper Triassic, the chigutisaurid Compsocerops sp. and Stereospondyli indet. (Dias-da-Silva et al. 2011, 2012) were collected at the base of the Candelária Sequence (Carnian, Santa Maria Supersequence, Paraná Basin, sensu Horn et al. 2014). Also, a single interclavicle of putative mastodonsauroid was yielded from the top (Norian) of the same sequence (Dias-da-Silva et al. 2009). Upper Triassic strata from Argentina had yielded Promastodonsaurus bellmanni from the Ischigualasto Formation (Ischigualasto Villa Unión Basin) of Argentina (Bonaparte 1963) and the chigutisaurids Pelorocephalus mendonzensis, P. cacheutensis, and P. tenax (Marsicano 1999, 2005) recovered from the Cacheuta and Rio Blanco formations (Cuyana Basin). Despite this diversity, the record of South American capitosaurs in the Early Triassic is still scarce. Capitosauroids are derived stereospondyls that reached global distribution during Triassic. So far, their diversity comprises about 24 and 44 valid genera and species respectively, from which the best known taxon is Mastodonsaurus giganteus (see CONTACT Estevan Eltink estevan.eltink@univasf.edu.br 2016 Informa UK Limited, trading as Taylor & Francis Group

3 2 E. ELTINK ET AL. Figure 1. Geological context. (A) Paraná Basin in the context of South America; (B) Geological map of the central region of Rio Grande do Sul state, southern Brazil, and location of the Bica São Tomé outcrop (star); (C) Satellite view of the Bica São Tomé site, showing the fossiliferous outcrops (1 5) and the outcrop 5 (star), in which Tomeia witecki was collected; (D) Photograph of the outcrop 5 in the Bica São Tomé site and the place (star) where the remains of Tomeia witecki were found. Schoch 1999; Schoch & Milner 2000; and others). During capitosauroid evolution, a singular feature emerged: a completely closed otic fenestra in the cheek (e.g. Cyclotosaurus) which renders to the group a key role as biostratigraphic marker of capitosaur-bearing beds (Schoch 2008; Lucas & Schoch 2002). The phylogenetic relationships of capitosaurs is controversial, despite many phylogenies that attempted to shed light into their evolutionary history (Säve-Söderbergh 1935; Romer 1947; Watson 1962; Ochev 1966; Shishkin 1980; Schoch 2000, 2013; Schoch & Milner 2000; Damiani 2001; Steyer 2003; Maganuco et al. 2009; Fortuny et al. 2011). Among a number of controversial points, we highlight both taxonomic discrepancies and phylogenetic definitions as well. For instance, the alternating use of two different superfamily names, Capitosauroidea or Mastodonsauroidea (for discussion, see Damiani 2001 and Schoch 2008). Besides nomenclatural issues, its phylogenetic definition also has different propositions, such as those by Yates and Warren (2000), Damiani (2001), Damiani and Yates (2003), and Schoch (2008, 2013). Despite the fact of being one of the most abundant groups of Triassic temnospondyls, known from Early Triassic deposits of most Gondwanic areas, as Australia, India, Madagascar, South Africa and Antarctica (Lehman 1961; Tripathi 1969; Colbert & Cosgriff 1974; Warren 1991; Damiani et al. 2001; Sidor et al. 2007, 2014; Maganuco et al. 2009), the record of capitosauroids in South America is still relatively scarce. Damiani (2001) and Piñeiro, Marsicano and Damiani (2007) argued that the relative absence of capitosauroids in South America is due to the insufficiency of extensive investigation. In Argentina, their record so far only comprises Promastodonsaurus bellmanni (Carnian of the Ischigualasto Formation) (Bonaparte 1963). The Brazilian record so far, includes only an interclavicle tentatively ascribed to Mastodontosauroidea (?) (Dias-da-Silva et al. 2009) recovered from the top of the Candelária Sequence, corresponding to the Caturrita Formation. Finally, Piñeiro, Marsicano and Damiani (2007) described mandibular elements tentatively ascribed to capitosauroids from the Buena Vista Formation (Uruguayan part of the Sanga do Cabral Supersequence, Paraná Basin). However, no specimens were formally described at specific level. Hence, Tomeia witecki fills an important gap, adding valuable information regarding capitosaurian data in South America. Preliminarily reported by Da-Rosa et al. (2009), Tomeia witecki comprises skull and mandibular remains. The material was recovered from the Sanga do Cabral Supersequence, Lower Triassic of Paraná Basin (locality of Bica São Tomé, São Francisco de Assis municipality, Brazil, Figure 1). Here, we provide a comparative description based upon related taxa (anatomical information regarding all taxa discussed the present study was taken from both first-hand examination and literature Table 1). In order to test the inner relationships of Tomeia witecki we performed a phylogenetic analysis including it in the data matrix by Fortuny et al. (2011).

4 HISTORICAL BIOLOGY 3 Table 1. List of taxa used for comparisons in the text. Taxon Geological setting Sources Lydekkerina huxleyi NHMUK R504; NHMUK R506; NHMUK R507; NHMUK R508; NHMUK R5482; CAMZM T.238; CAMZM T.110; Jeannot et al. (2006); Pawley and Warren (2005); Hewison (2007) Rhineceps nyasaensis CAMZM T.259; Watson (1962) Benthosuchus sushkini PIN 2-I9/2252; PIN 2424/10; PIN 3200/1; Bystrow and Efremov (1940) Melosaurus uralensis MB.Am 334 a-c; Meyer (1860) Konzhukovia vetusta PIN 520/1; PIN 520/8; PIN 520/10; PIN 520/11; PIN 4273/1; Gubin (1991) Watsonisuchus magnus Watson (1919, 1962) Kestrosaurus dreyeri SAM-PK-3452; Haughton (1925) Uranocentrodon senekalensis TM 75; TM 77; TM 185; Hoepen (1915); Broom (1930); Watson (1962) Broomistega putterili TM 184; Shishkin and Rubidge (2000) Laccosaurus watsoni SAM-PK-4010 (holotype); BP-1-213; Haughton (1925); Damiani and Rubidge (2003). Lapilopsis nana Warren and Hutchinson (1990); Yates (1999); Yates and Sengupta (2002). Peltobatrachus pustulatus CAMZM T.267; Panchen (1959) Arachana nigra Piñeiro et al. (2012) Watsonisuchus magnus Watson (1962) Warrenisuchus aliciae Warren and Hutchinson (1988); Warren and Schroeder (1995); Maganuco et al. (2009) Xenotosuchus africanus SAM-PK-2360; Morales and Shishkin (2002) Parotosuchus haughtoni Damiani (2002) Edingerella madagascariensis Steyer (2003); Maganuco et al. (2009) Thoosuchus jakovlevi PIN 3200/473 Mastodonsaurus giganteus SMNS 54675; Schoch (1999) Note: Source indicates the literature and the specimens first-hand analyzed from which the comparative data was gathered. Institutional abbreviation: CAMZM, University Museum of Zoology, Cambridge, UK; MB, Museum für Naturkunde, Humboldt Universitat, Berlin, Germany; NHMUK, Natural History Museum, London, UK; PIN, Paleontological Institute, Academy of Science, Moscow, Russia; SAM, Iziko South African Museum, Cape Town, South Africa; SMNS, Staatliches Museum für Naturkunde, Stuttgart, Germany; TM, Ditsong National Museum of Natural History (Transvaal Museum), Pretoria, South Africa. The Paraná Basin constitutes a large intracratonic depocenter, filled with marine, continental and volcanic rocks, from Ordovician to Cretaceous (Zalán et al. 1991). This basin extends over Brazil, Uruguay, Argentina, and Paraguay, in an area greater than 1.4 million km² (Milani et al. 1998). Its Triassic interval was designated as the 2nd order Gondwana II Supersequence (Milani et al. 1998), but later Zerfass et al. (2003) settled that the Early Triassic Sanga do Cabral Formation (Andreis et al. 1980) represents a separate second-order Supersequence, which also includes the Uruguayan Buena Vista Formation. The Brazilian portion of the Sanga do Cabral Supersequence overlies Aeolian sandstones attributed to the Pirambóia Formation and underlies the Santa Maria Supersequence, which comprises the Santa Maria and Caturrita formations (Middle/Late Triassic). Due to an overall discontinuity of the outcrops over a highly vegetated area, it is difficult to determine the total thickness of this geologic unit. Yet, Zerfass et al. (2003) estimates it is about 50 m (exceptionally 100 m). This unit is composed of massive to trough cross-bedded intraformational conglomerates and horizontally bedded fine orange sandstones that were interpreted as being deposited by braided river systems with poorly confined channels developed on a lowgradient alluvial plain (Holz & Souto-Ribeiro 2000). Towards the top, interbedded laminated mudstone lenses are present and have been related to deposition in small ponds and lakes (Scherer et al. 2000; Zerfass et al. 2003; Dias-Da-Silva et al. 2006). Systematic palaeontology Temnospondyli Zittel, Stereospondyli sensu Yates & Warren 2000 Capitosauria Yates & Warren 2000 sensu Damiani and Yates (2003) Tomeia witecki gen. et sp. nov. Etymology Tomeia, latin derivation of the name from the type locality, Bica São Tomé, formally described by Da-Rosa et al. (2009). The specific epithet honors MSc. Leopoldo Witeck Neto, a Brazilian forest engineer, landscaper, botanist, taxonomist, teacher, and an enthusiastic amateur paleontologist, who firstly spotted the fossiliferous site. Type material UFSM 11408: the right posterior corner of the skull, including otic notch, occipital region, parasphenoid, and pterygoid; a right fragment of the orbital region; an almost complete left postparietal; part of the left squamosal; a fragment of a right mandibular ramus. Also, some undetermined small fragments were found in association with the type material. Type locality and horizon The holotype of Tomeia witecki was recovered from the level 5 of the locality Bica São Tomé (Da-Rosa et al. 2009: Figure 1), municipality of São Francisco de Assis, Rio Grande do Sul, Brazil; Sanga do Cabral Supersequence (Paraná Basin), Lower Triassic. Diagnosis Tomeia witecki is distinguished from all other capitosaurs due to the following combination of characters: (1) intervening margin of parasphenoid preventing the ventral contact between exoccipital and pterygoid; (2) short suture between the parasphenoid and pterygoid when compared to those of derived forms from Middle and Late Triassic; (3) presence of extensive ornamentation on the ventral surface of the parasphenoid, a feature usually observed in Middle-Late Triassic capitosaurs; (4) oblique ridge more dorsally placed in comparison to other early-diverging capitosaurs like Watsonisuchus magnus and Edingerella madagascariensis; (5) a slit-like posttemporal fenestra (different from the more triangular and wide one observed in Watsonisuchus magnus); (6) extremely large paraquadrate foramen relative to the accessory paraquadrate foramen. Tomeia witecki also possesses a single autapomorphy: the descending postparietal lamina extending further ventrolaterally, occupying part of the ventral border of posttemporal fenestra, excluding the exoccipital from the border of the posttemporal fenestra.

5 4 E. ELTINK ET AL. Figure 2. Tomeia witecki (UFSM 11408). Notes: Photograph (A) and interpretative drawing (B) of the skull in dorsal view. Areas filled with parallel lines area are broken areas. Abbreviations: fcr, falciform crest; obc, oblique crest; pa, parietal; po, postorbital; ppa, postparietal; pt, pterygoid; qbo, quadrate boss; qj, quadratejugal; qd, quadrate; sq, squamosal; st, supratemporal; tab, tabular. Scale bars equal 5 cm. Figure 3. Tomeia witecki (UFSM 11408). Notes: Photograph (A) and interpretative drawing (B) of the skull in ventral view. Areas filled with parallel lines area are broken areas. Light grey represents sediment-infilled areas. Abbreviations: cm, crista muscularis; ex, exoccipital; ps, parasphenoid; pt, pterygoid. Scale bars equal 5 cm. Description The material comprises a fragmented skull and mandible. The skull roof is moderately thick with clearly distinguishable sinuous and interdigitated sutures. Its ornamented surface shows a uniform pattern of distribution (Figure 2), which mostly resembles that from early-diverging stereospondyls, such as Lydekkerina huxleyi and Rhineceps nyasaensis. In palatal view, the ornamentation is longitudinally disposed, remarkably visible on the palatine ramus of pterygoid (Figure 3). The dentition is only preserved in the mandibular fragment. Most of the teeth are broken, but in cross section they show a typical labirinthodont unfolding and, on their external surface, longitudinal grooves. The teeth are antero-posterioly compressed, a character observed in most stereospondyls (Schoch 2013). Preserved sensory channels comprise only a single shallow groove in the lateral border of jugal. The occipital sulcus is absent in the posterior margin of the skull roof (Figure 3, 4), differing from trematosauroids (Damiani & Yates 2003). In dorsal view, the orbit is placed close to the skull midline (Figure 5). The borders are slightly raised above the plane of the surrounding roofing bones, as in Lydekkerina huxleyi and Benthosuchus sushkini. Medially, the orbit is bordered by a small fragment of the postfrontal, which contacts the frontal, slightly entering the orbital margin. According to Damiani (2001), the inclusion of the frontal in the orbital margin is diagnostic for capitosauroids (excepting in basalmost taxa such as Wetlugasarus angustifrons and Odenwaldia heidelbergensis). However, the occurrence of this character seems to be more complex as frontal participation also appears in Melosaurus uralensis and Konzhukovia (Pacheco et al. 2016). Posteriorly, in the posterior border of the skull roof the postparietal forms a gentle concave margin. The tabular contacts the squamosal, isolating the supratemporal from the otic notch, a character present in Mesozoic stereospondyls (Schoch & Milner 2000; Damiani 2001). The tabular is posterolateraly projected and, ventrally,

6 HISTORICAL BIOLOGY 5 Figure 4. Tomeia witecki (UFSM 11408). Notes: Photograph (A) and interpretative drawing (B) of the skull in occipital view. Light gray represents broken areas. Dark grey represents openings or sediment-infilled fenestra. The white arrow indicates the autapomorphy. Abbreviations: exo, exoccipital; fc, falciform crest; memb, groove for insertion of medial tympanic membrane; obc, pblique crest; occ, occipital condyle; pob, paraoccipital bar; ppa, postparietal; pqf, paraquadrate foramen; ptf, posttemporal fenestra; qd, quadrate; qdb, quadrate boss; qj, quadratejugal; sq, squamosal; stg, stapedial groove; tab, tabular. Scale bars equal 5 cm. buttressed by the paraoccipital bar. The tabular horn is distally broken, but the preserved portion bears a moderately slight projection of the horn, as in other early-diverging capitosaurs, such as Watsonisuchus magnus and Kestrosaurus dreyeri. The result is a posteriorly wide opening of the otic border, differentiating Tomeia witecki from those advanced capitosauroids that present different degrees of closure in the otic notch, e.g. Cyclotosaurus and Eocyclotosaurus (Welles & Cosgriff 1965; Schoch & Milner 2000; Damiani 2001; Fortuny et al. 2012). Ventroanteriorly, the tabular bears the terminal crest and also the external tabular crest, as observed in many Mesozoic stereospondyls, such as Benthosuchus sushkini, Edingerella madagascariensis and Lyddekerina huxleyi (Yates & Warren 2000). The presence of these crests in Permian stereospondyls is putatively inferred for rhinesuchids, such as Uranocentrodon senekalensis and Rhineceps nyasaensis (Eltink et al. 2016). The anterolateral margin of the otic notch is bordered by the squamosal, which laterally contacts the quadradojugal and, medially, the supratemporal and the postorbital, forming most of the preserved cheek region. The falciform crest sensu Damiani (2001, 2002) runs along the posterior rim of the squamosal and part of the quadratojugal as well. This crest is gently convex and moderately pronounced (Figure 4). The relatively weak development of the falciform crest differentiates Tomeia witecki from advanced capitosauroids, in which a well-pronounced and curved flange is ventrally formed, as, for instance, in Mastodonsaurus giganteus. In Tomeia witecki, other isolated fragments are associated with both orbital region (Figure 5(A) and (B)) and skull roof, such as the posterior portion of squamosal and postparietal (Figure 5(D) and (E)). Another fragment bears a sigmoid and shallow groove, interpreted as the lacrimal flexure of the infraorbital sulcus (Figure 5(C)). Rather resembling the condition observed in early-diverging Triassic stereospondyls, as Lyddekerina huxleyi and Edingerella madagascariensis, this flexure is different from than that of advanced capitosaurs, in which it is a Z shaped lacrimal flexure, as in Mastodonsaurus giganteus. In ventral view, the preserved palate of Tomeia witecki comprises a nearly complete pterygoid, a fragment of the parasphenoid corpus and the quadrate (Figure 3). The pterygoid surface presents a conspicuous and longitudinally disposed ornamentation in the palatine ramus, which differs from that present in the skull roof where more uniformly distributed pits and excavations are present. The ventral ornamentation of the pterygoid is well represented in trematosaurs, but also present in some capitosaurs (Fortuny et al. 2011). Among early-diverging forms, like Wetlugasaurus angustifrons and Edingerella madagascariensis, it is possible to observe the same ornamentation. In early-diverging stereospondyls the ornamentation is variable, present in some rhinesuchids such as Laccosaurus watsoni, Uranocentrodon senekalensis, and Broomistega puttereli, as well as in Lapillopsis nana, Peltobatrachus pustulatus, and Arachana nigra. There are no observable denticles on the pterygoid surface of Tomeia witecki, which is quite different from the condition found in Benthosuchus sushkini (area aspera, sensu Bystrow & Efremov 1940). The suture between pterygoid and parasphenoid is shorter compared to the advanced capitosauroids, as Mastodonsaurs giganteus. As a result, the parasphenoid corpus is laterally wider than anteroposteriorly elongated, as seen in Watsonisuchus magnus. The parasphenoid corpus also bears some ornamentation on the ventral surface, but it is gentle in comparison to the pterygoid. The occurrence of an ornamented parasphenoid in Tomeia witecki suggests that it arose earlier than previously assumed in Capitosauroidea. It was previously observed in Xenotosuchus africanus, a South African capitosauroid from the Middle Triassic (Morales & Shishkin 2002; Damiani 2008). A transversally disposed, straight, and apparently continuous muscular crest is observed on the ventral surface of the parasphenoid corpus, well close to its posterior border. Posterolaterally, the crest bears a shallow excavation formed by the parasphenoid and the exoccipital (Figure 3). It differs from the pattern of excavation observed in early-diverging stereospondyls, as Rhinesuchidae and Lydekkerinidae, which have the muscular crest accompanied posteriorly by a deep recess, forming the so-called pockets (sensu Watson 1962) that are entirely placed on the ventral surface of the parasphenoid (Shishkin et al. 1996). The ventral contact between the exoccipital and the pterygoid is absent. Derived capitosauroids possess the suturing between these bones (Ingavat & Janvier 1981; Warren & Hutchinson 1988), differing from the condition observed in early-diverging forms, as Edingerella madagascarensis and Warrenisuchus aliciae. However, the lateral notch of the parasphenoid body (sensu Pawley & Warren 2005)

7 6 E. ELTINK ET AL. Figure 5. Tomeia witecki (UFSM 11408). Notes: Photographs (A, C and D) and interpretative drawing (B) of the skull fragments in dorsal view. A and B represent a right fragment of the orbital region; C, right lacrimal (?); D, left squamosal; E, left postparietal. Abbreviations: fr, frontal; j, jugal; lafl (?), lacrimal flexure; or, orbit; pa, parietal; pof, postfrontal; ppa, postparieral; prf, prefrontal; sq, squamosal; st, supratemporal. Scale bars equal 3 cm. found in early-diverging stereospondyls, such as Rhinesuchidae and Lydekkerinidae, is absent in Tomeia witecki. In occipital view, the quadrate boss (hyoid tubercle, sensu Morales & Shishkin 2002) is placed close to the quadrate/ pterygoid suture, as in Watsonisuchus magnus, Xenotosuchus africanus, Kestrosaurus dreyeri, and Benthosuchus sushkini. It is well prominent as in primitive capitosaurs, differing from the smooth derived condition (Schoch & Milner 2000; Schoch 2008). Medially, the quadrate underlies the posterior region of the quadrate ramus of the pterygoid. This quadrate ramus is posterolaterally oriented, resembling the condition observed in most capitosauroids, but different from Mastodonsaurus giganteus, in which it is laterally oriented. Apparently, the quadrate alone forms the upper jaw condyle. This condition does not match that asserted by Damiani (2001) for derived capitosauroids, in which the quadratojugal also takes part of the condyle. In ventral view, the quadrate condyles are posteriorly placed relative to the occipital ones, a condition shared with early-diverging capitosauroids, such as Edingerella madagascariensis, Watsonisuchus magnus, and Kestrosaurus dreyeri. The derived condition, in which the occipital and quadrate condyles are leveled to each other, occurs in some late-diverging capitosauroid genera, such as Mastodonsaurus and Cyclotosaurus (Schoch & Milner 2000; Damiani 2001; Schoch 2008). Laterally, the quadratojugal bears a well-developed paraquadratum foramen, forming a large aperture close to the suture with the squamosal. In comparison, the paraquadratum accessorium foramen is much smaller and dorsomedially placed relative to the paraquadratum one (Figure 4). The descending flange of the squamosal is well developed. Ventrally, it contacts the ascending ramus of the pterygoid. There is no palatoquadrate fissure, as occurs in Thoosuchus jakovlevi. The surface of the pterygoid ascending lamina is smoothly convex, bearing a remarkable oblique crest sensu Bystrow and Efremov (1940) (or otic flange sensu Watson 1962), as usual in many capitosaurs (Schoch & Milner 2000). The oblique crest is dorsally curved, placed close to the contact between the ascending lamina of the pterygoid and descending lamina of the squamosal (Figure 4). The crest is thicker than in Benthosuchus sushkini and more dorsally placed when compared to other early-diverging capitosaurs, such as Watsonisuchus magnus, Kestrosaurus dreyeri, and Edingerella madagascarensis. Laterodorsally, the oblique crest is accompanied by a quite remarkable stapedial groove sensu Watson (1962) (Figure 4). Ventrally, the ascending lamina of the pterygoid bears a shallow and straight groove that corresponds to the medial attachment for a membrane which separates the tympanic cavity (see Watson 1962; : memb. for Rhineceps nyasaensis). The tympanic crest sensu Shishkin et al. (1996) is absent in Tomeia witecki, differing from early-diverging stereospondyls such as lyddekerinids (Shishkin et al. 1996) and some rhinesuchids (Eltink et al. 2016). The posttemporal fenestra is narrow, drop-like, and horizontally orientated. This condition was described for Parotosuchus haughtoni, and it was considered unusual in capitosauroids (Damiani 2002). Ventrally, the descending process of the postparietal is well developed. It contacts the exoccipital, occupying the entire ventromedial border of the posttemporal fenestra, excluding the exoccipital from the posttemporal border here considered an autapomorphy of Tomeia witecki (Figure 4). The

8 HISTORICAL BIOLOGY 7 Figure 6. Tomeia witecki (UFSM 11408). Notes: Photographs (left) and interpretative drawings (right) of the mandible in lingual (A and B) and labial (C and D) views. Dark grey represents sediment-infilled fenestra. Abbreviations: a, angular; ac, anterior coronoid; de, dentary; mc, middle coronoid; pc, posterior coronoid; pmf, posterior meckelian fenestra; pra, prearticular; sa, surangular. Scale bars equal 3 cm. paraoccipital process forms a rodlike structure. The proximal half is constituted by the lateral expansion of the exoccipital and the distal half by the tabular descending expansion. The paroccipital process runs dorsolaterally rather than laterally, as seen in Parotosuchus haughtoni. In its anterodorsal surface it is possible to observe the terminal crest and, ventroposteriorly, the external tabular crest. Dorsolaterally to the the exoccipital condyle, at the basis of the external tabular crest, there is a large exoccipital foramen for the 10th cranial nerve sensu Bystrow and Efremov (1940). The lower jaw is represented by the middle portion of a right hemimandibular fragment (Figure 6). The dentary preserves at least 13, but mostly broken, teeth. In lingual view, the ventral portion is composed of the postsplenial and angular. The prearticular is not extended anteriorly, as observed in Mesozoic stereospondyls (Jupp & Warren 1986; Yates & Warren 2000). The posterior meckelian fossa is small and bordered by the postsplenial, angular and prearticular. Dorsally, the posterior coronoid bears six small, conical, and rounded teeth. This condition is also observed in those capitosauroid mandibles described by Piñeiro, Marsicano and Damiani (2007). The middle coronoid is anteroposteriorly short, reaching the dorsal border of the mandible. Labioposteriorly, the dentary is placed above the surangular. Phylogenetic analysis In order to assess the phylogenetic relationships of Tomeia witecki, we used the data-set by Fortuny et al. (2011), which is an updated version of Damiani (2001). It comprises 27 taxa plus 53 characters (Appendix includes the data added to the original analysis). The analysis was performed using TNT version 1.1 (Goloboff et al. 2008) under implicit enumeration ( traditional search ) with 10,000 replicates, randomly addition of taxa (random seed = 0), hold = 10, and TBR (tree bisection and reconnection) algorithm for branch swapping. The phylogenetic analysis recovered two most parsimonious tree with 141 steps each (CI = 0.41; RI = 0.70). Bootstrap (Holmes 2003) and Bremer support (Bremer 1994) values were calculated using 10,000 replicates. The topology of the consensus tree mostly matches that obtained by Fortuny et al. (2011). The position of Tomeia witecki was recovered as the sister taxon of Edingerella madagascariensis within Capitosauroidea (Figure 7). Discussion Systematic position and the capitosauroid features of Tomeia witecki The material attributed to Tomeia witecki was preliminarily assigned to Temnospondyli by Da-Rosa et al. (2009) based on the typical ornamentation of the skull fragments that herein comprise the holotype. Our results go further, supporting the phylogenetic assignment of Tomeia witecki to Capitosauria sensu Damiani and Yates (2003). Among the synapomorphies mapped to the capitosaurian clade (Figure 7), the following are present in Tomeia witecki: the excavations ( pockets ) entirely placed on the ventral surface of the parasphenoid, and a tall and well developed oblique ridge on the pterygoid. Damiani (2001) and Schoch (2008) also considered that these features are synapomorphies for Capitosauria. Tomeia witecki is nested in a less inclusive clade within Capitosauroidea sensu Schoch (2008), occupying a basal position among gondwanic capitosauroids, plus heylerosaurids and stenosaurids, a clade that is in agreement with the analysis of Fortuny et al. (2011). Among the synapomorphies mapped for Capitosauroidea, Tomeia witecki presents the frontal entering the orbit margin (Figure 5), a condition well established in the capitosaurian phylogeny (Damiani 2001; Schoch 2008). Tomeia witecki is the sister-taxon of Edingerella madagascariensis, forming a derived clade regarding the position of Watsonisuchus magnus. The close resemblance between Tomeia witecki and Edingerella madagascariensis is observed mainly in the occipital region of skull. The narrowed and slit-like posttemporal fenestra, a character considered plesiomorphic among stereospondyls, such as rhinesuchids (Shishkin et al. 1996; Eltink et al. 2016), is uncommon in the capitosaurian lineage, observed in Tomeia witecki and Edingerella madagascariensis, but absent in

9 8 E. ELTINK ET AL. Figure 7. The strict consensus tree of two most parsimonious tree depicting the phylogenetic position of Tomeia witecki. Note: Values of Bremer support and bootstrap percentages (in parentheses) are indicated for each node in the cladogram. Watsonisuchus magnus. The position of oblique crest, the opening of the foramen paraquadratum and the exoccipital excluded from the posttemporal fenestra differ Tomeia witecki from its close capitosauroid relatives, such as Edingerella madagascariensis and Watsonisuchus magnus (Figure 8). Schoch and Milner (2000) considered some Triassic stereospondyls, such as Edingerella madagascariensis and Watsonisuchus magnus, a paraphyletic grade termed as stem-capitosauroids. The Capitosauria sensu Damiani and Yates (2003) includes these stem forms, notably Wetlugasaurus angustifrons and Watsonisuchus magnus (Schoch 2008), but in the analysis of Fortuny et al. (2011), stem-capitosauroids as Edingerella madagascariensis and Watsonisuchus magnus were recovered in a basal node within the Capitosauroidea, more derived than Odenwaldia heidelbergensis and Wetlugasaurus agustifrons. Applying the node-based definition of Schoch (2013) for Capitosauroidea, which includes a clade containing Parotosuchus nasutus and Cyclotosaurus rubustus and all of their descendants, results in the exclusion of many well-known capitosauroids from the group, e.g. Stanocephalosaurus and Eocyclotosaurus, due to the relationship between Parotosuchus nasutus and Cyclotosaurus rubustus closer than to other capitosauroids. Future analysis focusing on stem-capitosauroids, as Edingerella madagascarensis, in the context of a broader phylogenetic analysis, configures a necessary step to provide more operational and stable definition to the capitosaurian lineage. Regarding the problem of the phylogenetic position of Wetlugasaurus angustifrons and Odenwaldia heidelbergensis (Ochev 1966; Maryańska & Shishkin 1996; Schoch & Milner 2000; Damiani & Yates 2003; Schoch 2008; Maganuco et al. 2009; Fortuny et al. 2011), we would rather adopt a conservative approach, discarding the inclusion of these taxa of Capitosauroidea (Figure 7). In Wetlugasaurus angustifrons, the frontal is excluded from the medial border of the orbit, an abovementioned capitosauroid synapomorphy. The anatomy of Tomeia witecki fully corroborates its inclusion in the capitosaurian lineage but, interestingly, the taxon possess an interesting combination of plesiomorphic features: the absence of contact between the pterygoid and the exoccipital, the posterolateral orientation of the tabular horn, the prominent quadrate boss, as seen in the most Early Triassic capitosaurs (Schoch & Milner 2000; Damiani 2001; Schoch 2008). Tomeia witecki also presents a smooth ornament on the ventral surface of the parasphenoid, which seems to be rather precocious for Early Triassic capitosauroids (M. Shishkin, personal communication). Therefore, these unique combination of features, some shared with early-diverging capitosauroids, and others shared with more derived taxa, plus the clear autapomorphy in the composition of the post-temporal fenestra border, support Tomeia witecki as a new capitosauroid taxon from the Lower Triassic of Western Gondwana, so far, the only undoubtful representative in the Sanga do Cabral Supersequence. Biostratigraphic implications So far, the faunal content of the Sanga do Cabral Supersequence is exclusively represented by fossil vertebrates, such as procolophonids (Cisneros & Schultz 2002; Cisneros 2008a), temnospondyls (Dias-Da-Silva et al. 2006; Dias-da-Silva & Schultz 2008; Da-Rosa et al. 2009; Dias-Da-Silva & Ilha 2009; Dias-Da-Silva & Milner 2010; Dias-da-Silva & Da-Rosa 2011; Dias-da-Silva &

10 HISTORICAL BIOLOGY 9 Figure 8. Skulls of early-diverging capitosauroids in occipital view. Interpretative drawing of Tomeia witecki (A) Edingerella madagascariensis (B) and Watsonisuchus magnus (C). Notes: The figures of Edingerella madagascariensis and Watsonisuchus magnus were based on the reconstruction of Maganuco et al. (2009: Fig. 14) and Watson (1962: Fig. 11(A)), respectively. The white arrows indicate the posttemporal fenestrae, the black arrows indicate the oblique crest and the grey arrows indicate the opening of the paraquadratum foramen Scale bar equals 10 cm. Dias 2013), synapsids (Abdala et al. 2002; Da-Rosa et al. 2009; Dias-da-Silva et al. 2011) and archosauromorphs (Da-Rosa et al. 2009; Dias-da-Silva & Da-Rosa 2011; Pinheiro et al. 2016). The temporal distribution of Procolophon trigoniceps, supports the early Olenekian age for the Sanga do Cabral Supersequence (Cisneros 2008b), and the other abovementioned specimens also point to an Early Triassic age for this unit. Alternatively, Piñeiro et al. (2015) suggest a Late Permian age for Sanga do Cabral Formation, based on isolated vertebrae found in the deposits. The results presented here reinforce the Early Triassic age for the Sanga do Cabral Supersequence (e. g. Sanga do Cabral plus Buena Vista formations, contra Piñeiro et al. 2015). A comprehensive geological, taxonomic and biostratigraphical reevaluation for the entire Sanga do Cabral Supersequence is detailed by Dias-da- Silva et al. (in progress). According to Schoch and Milner (2000) and Schoch (2008) stem-capitosauroid lineages are recurrently present in the Early Triassic. Indeed, the temporal distribution of early-diverging capitosauroids is supported by the presence of Watsonisuchus magnus and Kestrosaurus genus in the late Olenekian (Damiani & Rubidge 2003; Shishkin et al. 2004), Parotosuchus nasutus and P. orenburgensis in the middle Olenekian (Schoch 2008) and Edingerella madagascarensis spanning through the entire Olenekian (Yanbin et al. 2002; Maganuco et al. 2009). In this case, all these taxa are correlated to the Cynognathus Assemblage Zone (subzone A) of Karoo deposits, according to the division by Hancox et al. (1995), Shishkin et al. (1995) and Hancox and Rubidge (1997). The early-diverging capitosauroids Xenotosuchus africanus and Parotosuchus dirus are also correlated to the Cynognathus Assemblage Zone, but more recently distributed (subzone B early Anisian) (Damiani & Rubidge 2003). The results here presented, indicating a sister-group relationship of Tomeia witecki with Edingerella madagascariensis and Watsonisuchus magnus (Olenekian temporal distribution), suggest that the Sanga do Cabral Supersequence is Olenekian in age. Apart from Promastodonsaurus bellmanni described from Carnian Ischigualasto Formation of Argentina (Bonaparte 1963) and an interclavicle referred to capitosauroid described from the Upper Portion of the Candelária Sequence, Norian of Brazil (Dias-da-Silva et al. 2009), the earliest record of the group in South America come from capitosauroid mandibles described from the Lower Triassic Buena Vista Formation of Uruguai (Piñeiro & Ubilla 2003; Piñeiro, Marsicano & Damiani 2007). Furthermore, Tomeia witecki represents the first undoubted new capitosauroid species from the Early Triassic deposit of South America, which corroborates the Gondwanic distribution of the

11 10 E. ELTINK ET AL. group in the beginning of Mesozoic, later reaching a cosmopolitan distribution in the Middle and Late Triassic (Damiani 2001; Schoch 2008). Acknowledgements The authors thank the curators Rainer Schoch (SMNS), Florian Witzmann (MB), Mathew Lowe (CAMZM), Lorna Steel and Andrew Milner (UKNHM), Yuri Gubin and Mikhail Shishkin (PIN), Sheena Kaal (IZIKO), Heidi Fourie (TM), who allowed the access to the examined specimens. We also thank Fabiano F. Feltrin, Graciela Piñeiro and Juan C. Cisneros for their initial efforts in the study of the material. Disclosure statement No potential conflict of interest was reported by the authors. Funding This work was supported by the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) for the scholarship to EE [grant number 2009/ ]. References Abdala F, Dias-da-Silva S, Cisneros JC First record of nonmammalian cynodonts (Therapsida) in the Sanga do Cabral Formation (Early Triassic) of Southern Brazil. 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