New discoveries of vertebrate remains from the Triassic of Riba de Santiuste, Guadalajara (Spain)

Proceedings of the Geologists’ Association 129 (2018) 526–541

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New discoveries of vertebrate remains from the Triassic of Riba de Santiuste, Guadalajara (Spain) Mélani Berrocal-Caseroa,* , Julia Audije-Gilb,c , Rui Alexandre Castanhinhad,e , Juan Alberto Pérez-Valeraa,f , Vanda Faria dos Santosg , Manuel Segurab a

Grupo de Investigación Procesos Bióticos Mesozoicos, Departamento de Paleontología, Universidad Complutense de Madrid, 28040 Madrid, Spain Grupo de Investigación IberCreta, Departamento de Geología y Geografía, Universidad de Alcalá, 28871 Alcalá de Henares, Spain Departamento de Biología, Laboratorio de Poblaciones del Pasado (LAPP), Universidad Autónoma de Madrid, 28049 Madrid, Spain d Department of Biology and CESAM, University of Aveiro, 3810-193 Aveiro, Portugal e Museu da Lourinhã GEAL, 2530-158 Lourinhã, Portugal f Departamento de Ciencias de la Tierra y Medio Ambiente, Universidad de Alicante, 03690 San Vicente del Raspeig, Spain g Departamento de Geologia, Faculdade de Ciências da Universidade de Lisboa, Edifício C6, Campo Grande, 1749-016 Lisboa, Portugal b c

A R T I C L E I N F O

Article history: Received 20 November 2017 Received in revised form 11 April 2018 Accepted 21 April 2018 Keywords: Nothosaurs Placodonts Rauisuchia Swim traces Ladinian Spain

A B S T R A C T

The palaeontological sites of Riba de Santiuste and Sienes (Riba de Santiuste area) are located in the province of Guadalajara, Spain. They include a stratigraphic interval in Muschelkalk facies belonging to the “Cuesta del Castillo Sandstones” Formation and “Royuela Dolostones, Marls and Mudstones” Formation. These sites include numerous fossil plants, direct vertebrate remains, and vertebrate swim traces. The vertebrate remains correspond to a multitude of anatomical elements of Sauropterygia (Nothosauroidea, Placodontia) and possible Archosauria (Rauisuchia) remains. The fossil material attributed to nothosaurs includes teeth, coracoids, a thoracic vertebra, some isolated vertebral centra, humerus, rib fragments, and some dorsal and caudal vertebrae. The remains attributed to placodonts correspond to fragments of skull, quadrate, teeth and osteoderms. Other undetermined sauropterygian remains, such as ulnas, fragments of long bones, fragments of ribs, and articular facets of ribs have been also recovered. Additionally, a fragment of mandible and an intervertebral disk of indeterminate reptiles whose size could be compatible with archosaurs are also described. These bones are exceptionally wellpreserved because the fossilization processes have preserved the microstructure of the tissues. The sites also show vertebrate traces, with parallel scratch impressions interpreted as swim traces. The relative stratigraphic position and the palaeontological content of these sites suggest a Ladinian age (Middle Triassic). The interpretation of the sedimentary facies here described also suggests that the sites could correspond to detrital-carbonate mixed deposits of coastal intertidal to supratidal environments. © 2018 The Geologists' Association. Published by Elsevier Ltd. All rights reserved.

1. Introduction Middle Triassic faunas in Spain reflect the change from continental depositional environments to a wide diversity of coastal and marine environments. Triassic vertebrate assemblages are mostly represented by marine taxa (Sanz et al., 1993), whereas the non-marine Triassic units have rarely been reported as containing vertebrate skeletal material (Knoll et al., 2004; Witzmann and Gassner, 2008). The Spanish record of Triassic fossil plants, vertebrate remains, and vertebrate traces is far from being well documented, but the studies in Triassic faunas are increasing in

* Corresponding author. E-mail address: [email protected] (M. Berrocal-Casero).

recent years, especially in sauropterygians. The Triassic record of sauropterygians is mainly represented by fragmentary remains attributed to Nothosauridae in the Western Iberian Range (Rieppel, 2000; Ortega et al., 2009; Miguel Chaves et al., 2015a,b, 2016, 2017). The Riba de Santiuste area is an exceptional place due to the excellent preservation of the inorganic and organic structures and by the information that they provide for the reconstruction of the Triassic sedimentary environments (Sánchez-Moya et al., 2015). In this paper, the geological content and the new palaeontological content that includes plants, brachiopods, bivalves, vertebrate bone remains and vertebrate traces, which have been found during different fieldworks undertaken in the last years in the Riba de Santiuste area, are described. This area has provided multiple fossil remains of several Sauropterygia (Nothosauroidea, Placodontia) and some possible archosaur remains (Rauisuchia) with an

https://doi.org/10.1016/j.pgeola.2018.04.009 0016-7878/© 2018 The Geologists' Association. Published by Elsevier Ltd. All rights reserved.

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exceptional mode of preservation. The possible presence of skeletal remains of rauisuchians is particularly interesting because few occurrences are known in the Middle Triassic of the Iberian Peninsula. The present work adds considerably to the fossil diversity and abundance previously cited in this place, focusing the study on the discovery of new vertebrate remains. 2. Geographical and geological setting The palaeontological sites of the Riba de Santiuste area are located in the North-West of the Province of Guadalajara, Central-Eastern Spain (Fig. 1A). This area corresponds to the Riba de Santiuste Anticline and Sienes (Fig. 1B-C). The Riba de Santiuste Anticline comprises a series of sites (Riba 1–6) that are close to Riba de Santiuste, Valdelcubo and Tordelrábano (Fig. 1B–D). This asymmetric anticline follows N-S direction, and its dip gradually decreases on its western flank. The anticline is composed of Triassic materials that include Buntsandstein, Muschelkalk and Keuper facies. As have been exposed by Pérez-López and Pérez-Valera (2007), in the Iberian Peninsula several units have been described based on palaeogeographic differences among its triassic deposits. The main criterion used for this classification is the presence of Muschelkalk facies in the different outcrops, taking into account their thickness or whether the carbonate levels show detritic intercalations. The most recent classification scheme is that described by LópezGómez et al. (1998) who differentiate the following palaeogeographic units: Hesperian Triassic, Iberian Triassic, Mediterranean Triassic and Levantine-Balearic Triassic. This classification was studied and completed by Pérez-López and Pérez-Valera (2007: figs. 3 and 7), who adding also South Iberian Triassic and MesoMediterranean Triassic for correlating the Triassic of the Betic Cordillera with the palaeogeographic units of the Iberian Peninsula. The study area is situated in the conjunction of the Iberian Range and the Central System between the Iberian-type Triassic (characterized by the presence of a carbonate bar corresponding to the upper Muschelkalk facies) and the Hesperian-type Triassic (mainly siliciclastic). In this area, a change of facies to the upper carbonate unit of the Muschelkalk occurs (García-Gil, 1991, 1994). Thus, the Muschelkalk facies of the Iberian Ranges changes laterally into siliciclastic deposits to the NW. The junction between the Iberian Ranges and the Central System was a key region during the Middle Triassic, because this area constituted the western sector of the Tethys basin margin during that time. In the Riba de Santiuste Anticline, the Muschelkalk facies begin with the “Tramacastilla Dolostones” Formation (Pérez-Arlucea and Sopeña, 1985). In this area, this formation is composed of dolostones and dolomitic sandstones of around 10 m thick, which show microbial lamination, and corresponds to mixed tidal flat according to García-Gil (1991). Some fossil remains are located in the overlapping “Sandstones and Siltstones of Cuesta del Castillo Formation” (García-Gil, 1990, 1991). The thickness along the fold is variable, reaching up to 12 m in the eastern flank of Riba de Santiuste Anticline. These sandstones and siltstones show wellpreserved sedimentary organic and inorganic structures, such as bioturbation, cross stratification, lingual ripples marks (Fig. 1E), current ripple marks, oscillation ripple marks (Fig. 1F), interference ripple marks (Fig. 1G), flute cast, and fossil remains (plants, bivalves, brachiopods and fragmented vertebrates). This unit corresponds to fluvio-deltaic facies interpreted as tidal flats facies in the lower part, with channels in the upper part. In the Riba the Santiuste Anticline, the uppermost part of this unit is equivalent to the carbonate ramp facies association unit “Royuela Dolostones, Marls and Limestones Formation” (Pérez-Arlucea and Sopeña, 1985), according to García-Gil (1991). Dolomitic marls, dolostones,

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sandy dolostones, sandstones and shales compose the lithology of this Formation. This unit contains the richest diversity and content of fossils (bivalves, brachiopods and vertebrate remains) (Fig. 1H); and some levels show abundant organic Rhizocorallium structures. The Royuela Formation was deposited in shallow marine environments. In this place, a lateral change of facies is produced between these two formations (Cuesta del Castillo Formation and Royuela Formation; García-Gil, 1991, p. 30). The terrigenous detritic intercalations disappear in the Sienes outcrop. A characteristic level of Tepee structures is identified at the top of Muschelkalk facies in the section (Fig. 1I), according to García-Gil (1990). The palaeoenvironment of the upper part of the section (Fig. 2) corresponds to detrital-carbonate mixed deposits of coastal intertidal to supratidal environments to the top (Sopeña, 1979; García-Gil, 1991). Regarding the age of the materials, in the top of the Royuela Formation, Sopeña (1979) described some pollen assemblages that were common in the Carnian, while the boundary LadinianCarnian could be close to the top of Royuela Fm. according to García-Gil (1991). Pollen assemblages studies carried out in Cuesta del Castillo Fm. attributed this unit to Upper Ladinian (García-Gil et al., 2005). Additionally, in the Riba de Santiuste Anticline, close to Valdelcubo, a few specimens of nautiloids were found in the upper part of the sections (p. 245; Sánchez-Moya et al., 2015: 15, Fig. 12). Goy and Martínez (1996) proposed the new species Picardiceras sopegnai, for the notably mentioned, more evolute and compressed nautiloids with deep umbilicus, flattened venter and larger adult size. The age of this taxon was assigned to the Upper Ladinian by Goy and Martínez (1996). This species has been confirmed as Upper Ladinian in a recent nautiloid revision by Pérez-Valera et al. (2017: 187, Fig. 13). 3. Historical background The geology of the Triassic of Riba de Santiuste area was mainly studied by Sopeña (1979),Sánchez-Moya (1992) and García-Gil (1991) during completion of their PhD Thesis. During their studies in the area, the existence of invertebrate and vertebrate remains was observed by Sopeña (1979), and later by García-Gil (1990, 1991, 1994). Márquez-Aliaga and García-Gil (1991) studied the geological and palaeontological content of the Triassic in the NW Iberian Ranges, and mentioned some remains of marine vertebrates, but their study was focused in invertebrate faunal associations. These authors identified Lyriomyophoria cf. sublaevis, Pseudocorbula gregaria, Lingula sp. and Lingula tenuissima in the Riba de Santiuste area. In this place, Alafont (1999) described some invertebrates and several isolated sauropterygian fossil remains, and Fortuny et al. (2011) mentioned the presence of nothosaurs and placodonts. Most of the marine vertebrate remains documented to date from the Spanish Triassic, consist of isolated elements, attributed to indeterminate nothosaurs, pachypleurosaurs, and placodonts (Almela and Llopis Lladó, 1947; Bauzá, 1955; Kuhn-Schnyder, 1966; Lapparent, 1966; Westphal, 1975; Vía Boada et al., 1977; Sanz, 1980, 1983; Alafont, 1992, 1999; Sanz et al., 1993; Alafont and Sanz, 1996; Rieppel and Hagdorn, 1998; Niemeyer, 2002; Rubio et al., 2003; Quesada and Aguera González, 2005; Reolid et al., 2013; Miguel Chaves et al., 2014a,b, 2015a,b; Berrocal-Casero and Castaninha, 2015). These specimens were collected in several Spanish Triassic sites in Huesca, Jaén, Balearic Islands, Guadalajara, Teruel, Albacete and Tarragona. The most complete specimen corresponds to an articulated and almost complete skeleton of a Lariosaurus balsami notosaur from the Ladinian (Middle Triassic) of Aragón, Huesca (Ferrando, 1912; Sanz, 1976; Miguel Chaves et al., 2015a,b). In 2009, some sauropterygian remains from the Keuper of El Atance (close to Riba de Santiuste, Guadalajara) were preliminarily referred to

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Fig. 1. Geographical context of study area (A-B). Geological context showing the Riba the Santiuste area that include the Riba the Santiuste Anticline (C). The fossil site comprises the two flanks of the anticline in Muschelkalk facies and includes the sites 1–6 and the palaeontological site of Sienes. Eastern flank of Riba de Santiuste Anticline (D). Lingual ripple marks (E). Oscillation ripple marks (F). Interference ripple marks (G). Dolostone with bone remains, Scale bar: 1 cm (H). Tepee structure (I).

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Fig. 2. General synthetic stratigraphic section of Riba de Santiuste area showing the Muschelkalk (Basin border facies) that comprises Tramacastilla Dolostones Formation, the Cuesta del Castillo Sandstones Formation and Royuela Dolostones, Marls and Limestones Formation. In the Upper part of Muschelkalk a lateral change of facies is produced between these two formations (Cuesta del Castillo Fm. and Royuela Fm.).

the genus Simosaurus (Quesada et al., 2009), and were later described as aff. Simosaurus (Miguel Chaves et al., 2014b). In the last years, some vertebrae from the Middle Triassic of Soria were assigned to Nothosaurus cf. giganteus (Miguel Chaves et al., 2016), and the presence of simosaurs were described in the Carnian of the Province of Guadalajara (Miguel Chaves et al., 2017). Other Triassic tetrapod taxa recovered from Spain include: Ichthyosaur remains from Catalonia (Fortuny et al., 2011); a tail fragment of a probable thalattosaur and the holotype specimen of Cosesaurus aviceps, and a skeleton of a protorosaur, both from the Ladinian of Tarragona, Catalonia (Ellenberger and Villalta, 1974;

Ellenberger, 1977, 1978; Rieppel and Hagdorn, 1998); remains of procolophonids archosauromorphs from the Anisian of Barcelona, Catalonia (Gaete et al., 1993, 1996), and ichthyosaur remains from Teruel (Miguel Chaves et al., 2015a,b). Tetrapod tracks have been reported from the Iberian Peninsula. In the studied area, Sopeña (1979) mentioned some vertebrate tracksites in Triassic materials, and he conducted a study in the Iberian Ranges about tracksites of Chirotherium, Batrachopus and Rhynchosauroides. Demathieu et al. (1978) described some archosaur ichnites in the Muschelkalk of the Riba de Santiuste Anticline. Close to Riba-6, Meléndez and Moratalla (2014)

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described different archosaur tracks and trackways, whose trackmaker correspond to Rauisuchia (Archosauria). Nevertheless, these studies in the area were focused in tracks and trackways without swim traces. In spite of Triassic swim traces, fossil tetrapod swim traces have been reported from deposits throughout the world, ranging in age from the Carboniferous to the Neogene (Thomson and Droser, 2015). According to these authors, Triassic strata contain a high number of occurrences in the world, and Triassic swim traces tend to be better preserved, showing exceptional detailed features such as scale striate and crescent-shaped claw margins. 4. Material and methods During a general geological study carried out in the Riba de Santiuste area, some Middle Triassic vertebrate remains, mainly of sauropterygians, have been collected and studied in detail. The preservation of three bones of the sample from three different points of the area has been studied macroscopically and microscopically, in order to enrich fossilization process knowledge. The samples selected for this analysis were a fragment of a sauropterygian unidentified long bone from the east flank the Riba de Santiuste Anticline (Fig. 3A), two placodont connected osteoderms (Fig. 3B) from the western flank of the same Anticline, and a Euryapsida fragment of bone from Sienes (Fig. 3C). Macropreservation of the bones was observed and photographed. Afterwards palaeohistological analyses of three bones were performed. Thin sections were prepared and the microstructure was observed and photographed, using polarized light microscopy. All the specimens described here are housed in the collection of the Department of Palaeontology at Complutense University of Madrid (UCM). 5. Taphonomy Plants are usually preserved as carbonified remains. Some bivalves have been recovered as carbonate shells, while other are

preserved as internal and external moulds. Overall, the bone, teeth and other biomineralized remains from the Middle Triassic of this area seem to be well preserved. Most of the bones can be identified due to the exceptional state of preservation of the site. Macroscopically, the fragment of the sauropterygian unidentified long bone from the Riba de Santiuste Anticline present a fractured periosteum, leaving the surface of the endosteal part of the bone exposed. The Euryapsida fragment of bone from Sienes presents an altered (eroded) periosteal surface too. The placodont connected osteoderms from the Riba de Santiuste anticline shows some differences compare to the other samples, presenting different coloring patterns, surface microfractures and sediment infilling. Microscopically, the histological characteristics of the remains from the two outcrops are exceptionally preserved because the conditions of fossilization process have preserved the microstructure of the bones. Moreover, the osteocytes lacuni can be seen and the general histological microstructure presents birefringence that allows to observe the orientation of the collagen fibers and to identify tissue typologies. In the sauropterygian unidentified long bone (Fig. 3A) two different microstructures are observed in the bone tissue, which correspond to the fractured periosteum and the endosteum of the bone. In the fractured periosteum (external area), the bone matrix consists of lamellar bone, where parallel lamination corresponding to different growth marks can be identified. The endosteum of the bone consists of a fibrocartilaginous bone matrix. This tissue typology has been previously identified in Placodontia and revealed the presence of cartilaginous tissues, which are related to the ossification process, in the postcranial elements of the Middle Triassic sauropterygians. On this sample, the fibro-cartilaginous bone is vascularized with large vascular spaces (that are in a laminar and longitudinal vascular pattern). The longitudinal vascular channels are filled with a microcrystalline texture of carbonate composition identified as micrite. The entire matrix of the two placodont connected osteoderms consist of lamellar bone with different orientation of the laminations (Fig. 3B), little vascularization in both

Fig. 3. Details of tissue typologies and taphonomical observations of the three thin sections of the sample: sauropterygian unidentified long bone UCM-palR3E1013 (A), two placodont connected osteoderms UCM-palA14072 (B), and Euryapsida fragment of bone UCM-palS20031501 (C). Terminology: FCB = fibro-cartilaginous bone, Fe = Iron infilling, LB = Lamellar bone, mcracks = microcracks, PFB = Parallel fibered bone, vasc = vascularization. Scale bars = 0,5 mm.

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osteoderms and lamination corresponding to different growth marks. The suture of both osteoderms are filled with sediments and three phases of infilling can be observed: ferruginous infilling, formation of calcite crystals, and formation of micrite. This sample and the sauropterygian unidentified long bone present microcracks through the lamellar bone in which the sediment has infilled in the direction of growth marks and perpendicular. The Euryapsida fragment of bone presents in the periosteal area a matrix of parallel fibered bone with several longitudinal vascular canals, including secondary osteons among them (Fig. 3C). Most of the vascular canals are filled with ferruginous material. The endosteal area consists of a fibro-cartilaginous bone matrix with large vascular spaces, which are partially filled by sediment. Again, in the phases of infiltration of iron, micrite and calcite. This bone shows transverse random microcracks on the surface. These microcracks are usually produced during the fossildiagenetic phase (Fernández-López, 2000). 6. Fossil content Samples collected from the Riba de Santiuste area have yielded plant, invertebrate and vertebrate remains (Fig. 4A–H), providing new palaeontological information. Numerous isolated vertebrate bones have been found, and include vertebrae, ribs, osteoderms and other remains, most of which can be assigned to Sauropteygian (e.g., Nothosauria and Placodontia). In all these sites of the Riba de Santiuste Anticline, and specially, in Riba-5 (Fig. 1), the abundance of small nothosaur teeth is noteworthy. At Sienes, vertebrate remains are scarcer and invertebrate remains are not wellpreserved, but vertebrate remains maintain their well preservation.

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of medium to small size (around 2 cm) specimens. They are equivalve, oblong and inflated. The umbones within interior half are broadly rounded. These moulds are bad preserved, but their features seem to correspond to Pleuromya sp. (Fig. 5C–E), appearing only in marly levels at the upper part of the section. The remaining bivalve consist in sandy moulds of bivalves. Some of them are small (0,4–1,5 cm) triangular in outline, equivalve and moderately inequilateral. The beak is prosogyrus and situated in a forward position. The ornamentation of the valve consists in unevenly spaced ribs (until nine ribs have been visible in some moulds), which extend from the umbo to the ventral margin. These features correspond to Costatoria killiani (Fig. 5F). They appear in sandy levels in the upper part of the section. Lyriomyophoria cf. sublaevis have also been identified in the same levels. They appear as small size moulds (0,5–1 cm), with ovate to trigonal shape, equivalve, inequilaterally and convex. The ornamentation consists in concentric alight ribbing (Fig. 5G-H). This bivalve assemblage is typical from the Ladinian of the Sephardic Province, and has been recognized and well represented in others outcrops of the Iberian and Betic Ranges from Spain (Márquez-Aliaga et al., 1986; Escudero-Mozo et al., 2015), and Negev (Israel) and Sinai (Egypt) (Lerman, 1960). 6.3. Vertebrates

6.2. Invertebrates

Vertebrate remains consist of isolated fragments of Sauropterygia and other undetermined bones, possibly corresponding to archosaur rauisuchians. These remains do not display a preferential orientation and, in most of the cases, the fragments fit together. The most abundant remains are nothosaur vertebral centra, nothosaur and placodont fragment of ribs, teeth, and placodont osteoderms (Figs. 6–8). These remains are mainly located in carbonatic levels of the upper part of the section (t3) (Fig. 2). The main concentration of bones appears below a characteristic level, which contains a high concentration of milimetric Pseudocorbulagregaria (Fig. 2). The skeletal elements are identified as from nothosaurs, by direct comparison with material of Alafont (1992) and bibliographic descriptions of several authors (e.g., Sanz, 1980; Alafont, 1999; Miguel Chaves et al., 2016) of material from Spain, and bibliographic descriptions from the Germanic Basin (e.g., Rieppel and Wild, 1996).

Fossil invertebrates, in general, are scarce at the Triassic of Riba de Santiuste. There are no findings of ammonoids so far, although it is important to emphasize the presence of some specimens of nautiloids in the area (Goy and Martínez, 1996). During the present research, several inarticulate brachiopods and bivalves have been collected (Fig. 5A–H). Among them, some millimetric inarticulated phosphatic brachiopods have been recovered at the upper part of the section (Fig. 2). These brachiopods are 3,5–6 mm long, and around 2 mm wide, with elongate oval to subrectangular shell. These brachiopods have been classified as Lingula sp. (Fig. 5A). The internal features have not been observed and it is difficult to identify species based on external shape and size, but they could correspond to Lingula tenuissima, previously identified by Márquez-Aliaga and García-Gil (1991) in the Ladinian of this area and other Ladinian outcrops of the Iberian Ranges. Small internal moulds mainly represent the bivalves that appear on these sections, but some taxa also preserve the shell. Some of them consist of millimetric bivalves (around 4 mm), with subtriangular to inequilateral shape. They correspond to Pseudocorbula gregaria (Fig. 5B) and appear as numerous individuals covering the top of some carbonate levels (Fig. 2). This taxon also uses to appear with Lingula sp (Lingula-Pseudocorbula association) in some carbonate levels. Other bivalves consist of internal moulds

6.3.1. Nothosaurs Although the reptile remains from the Middle Triassic of the Riba de Santiuste area studied here are isolated and fragmentary, most of them provide enough information to identify them as Nothosauroidea. Some teeth (Fig. 6A–D), a coracoid (Fig. 6E), a complete first thoracic vertebra (Fig. 6F), a complete neural arch of nothosaur dorsal vertebra (Fig. 6G), some isolated vertebral centra (Figs. 6H–7B), some caudal vertebrae (Fig. 7C and D), some fragments of ribs (Fig. 7E), and one?humerus (Fig. 7F) of nothosaurs have been found in the Riba de Santiuste area. Different nothosaur teeth have been found in different points of the Riba de Santiuste Anticline (Riba 5–6). These teeth are represented by different morphotypes (Fig. 6A–D). One morphotype corresponds to conical and flattened teeth, showing a certain curvature with their concave margin on a linguo-distal position, and well-differentiated stretch marks on its surface (Fig. 6A). One of them is complete, with a maximum length of 2,5 cm (Fig. 6A). Other incomplete tooth shows similar features, but it is more flattened and shows stronger longitudinal ornamentation on the crown with widely spaced thick ridges (Fig. 6B). Other morphotype teeth includes complete conical and less flattened, showing softer striation (Fig. 6C and D). Two teeth are less than 1 cm, showing the striation from the root disappearing occlusally (Fig. 6B–D) and the cusp is covered by shiny, smooth enamel (Fig. 6D). A characteristic

6.1. Plants Plant remains consist mainly of numerous fragments of carbonified wood, among which some macroremains can be identified (Fig. 4A and B). Some of them show slightly auriculate pinnules, that could correspond to Scolopendrites? relatively frequent during the Ladinian (Kustatscher et al., 2005).

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Fig. 4. Carbonified plants remains of Scolopendrites? (A). Undetermined plant remains (B) Nothosaur humerus? in situ (C) (note the mould still visible in the missing part). Sauropterygian vertebra (D). Indeterminate bone remains (E). Undermined vertebrae (F). Placodont teeth from Riba-1 (G, H). Scale bars: 1 cm.

feature in nothosaurs teeth is the folding of the enamel, producing the appearance of grooves and striates on the surface of the crown. Conical, slender, pointed and recurved teeth with this type of ornamentation have been associated with Nothosauridae teeth in the Triassic of Spain (e.g., Sanz, 1980; Alafont, 1992).

An incomplete coracoid has been found (Fig. 6E) in the eastern part of the Riba de Santiuste Anticline. It is a fragmented right coracoides in ventral view. The anterior and dorsal margins are joined giving the coracoid a sub-quadrangular shape. This bone is similar to some parts of nothosaur coracoides described by Alafont

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Fig. 5. Lingula sp. (A). Pseudocorbula gregaria (B). Pleuromya sp. (C-E). Costatoria killiani (F). Lyriomyophoria cf. sublaevis (G-H). Scale bars: 1 cm.

(1992) and Niemeyer (2002) in the Muschelkalk of the Province of Jaén (Spain). Although the nothosaur vertebral centrum and the neural arch usually do not appear in one piece, a complete, well-preserved first thoracic vertebra linked to the neural arch has been recovered in the Riba de Santiuste area (Riba-5). The total height of the vertebra is 5,2 cm, and shows 3,8 cm in width, whereas the maximum diameter of the centrum is 2 cm, and its dorsal arch is 2,9 cm in height (Fig. 6F). The anterior and posterior articular facets of the centrum show sub-circular outline and are wider than higher. In posterior view, the neural arch shows a zygantrum that consist in two ovoid symmetric depressions in the posterior side of the neural arch separated by a thin lamina of bone. The articulation for the ribs can be observed (Fig. 6F.3). The vertebral foramen is

semicircular in shape. These vertebrae seem to correspond to a Nothosauridae first thoracic vertebra. An isolated neural arch (Fig. 6G) has appeared in Riba-6. The arch is wider than high, being 3,5 cm of height by 5 cm of width, and its thickness is of about 0,4 cm. It shows a sub-triangonal to sub-rectangular outline. Dorsally, the neural canal is ovoid, taller than wider and narrower at the lower part, with the convex part up. The zygantrum and postzygaphophysis (only one postzygaphophysis is preserved, while the other is broken) can be observed. The zygantrum consist of two oval and symmetric depressions in the posterior part of the neural arch. The neuroapophysis is broken by its base. This arch is similar to those of other eosauropterygians arches described in the Muschelkalk of Spain (e.g., Alafont, 1999; Niemeyer, 2002; Miguel Chaves et al., 2017).

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Fig. 6. A-D: Nothosauridae teeth, A: UCM-palC20031508 from Riba-2. B: UCM-palC20031509 from Riba-2. C: UCM-palC20031510 from Riba-2. Lingual view (C1), labial view (C2). D: UCM-pal 10101404 from Riba-2. E: Fragment of possible nothosaur coracoides UCM-pal C21031502IS from Riba 2. F: Nothosauridae first thoracic vertebra. UCMpalV18011501 from Riba-3 different views: anterior (F1), posterior (F2), left lateral (F3). G: Complete neural arch of nothosaur dorsal vertebra UCM-pal A10101402 in: anterior (G1) and posterior (G2) views. H-L: Nothosaur isolated vertebrae centra. H: UCM-palV18101402 in: dorsal (H1), anterior (H2), and ventral (H3) view. I-K: Isolated vertebral centrum in dorsal view UCM-palV10101400, UCM-palV18101404, L: Isolated vertebral centrum UCM-palV18101403 in: dorsal (L1), ventral (L2) and lateral (L3) views. Scale bar: 0,5 cm for 1,1 cm for B-D, and 1 cm for E-L.

The nothosaur remains are mainly represented by isolated vertebral centra of different sizes ranging from 0,8 cm to 5 cm (in A/P length) (Figs. 6H–7B). These vertebral centra are platycoelus to slightly anphicoelous in some cases. Some of those centra are ventrally constricted in lateral view. They are non-notocordal. Some of them are strongly constrained dorsoventrally, resulting in relatively flattened elements. One of them does not correspond to a thoracic vertebral centrum, being ventrally keened and presenting an articulation for the ribs (Fig. 6H). Others centra belong to the dorsal region, being characterized by the absence of intercentrum and articular heads for the ribs (Fig. 6I–L). Some centra of the vertebrae present a characteristic cruciform-sutural facet

(“Kreuzform”) in dorsal view (sensu Rieppel, 1994) (e.g., Fig. 6H) formed by a longitudinal groove, which could have passed the neural channel and it is crossed perpendicularly in the middle by another groove, where a basal ridge of the neural arch could have been filled. Nevertheless, some of these centra show the dorsal surface copiously widereded providing a very characteristic “butterfly-shaped” (sensu Rieppel, 1994) for the neural arch (e.g., Fig. 6I). A small Nothosauroidea vertebral centrum (0,7 cm long and 0,5 cm wide) shows a ventral knell and posteriorly bifurcated, conforming the articular facets for the chevrons (Fig. 7B), indicating a caudal position (Rieppel, 1994, 2000). Other different

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Fig. 7. A-B: Nothosaur isolated vertebral centrum UCM-palV18101406 from Riba-3 in dorsal (A1), ventral (A2) and posterior (A3) views. B: UCM-palV18101405 in dorsal (B1), lateral (B2) and posterior (B3) views. C-D: Nothosaur caudal vertebra C: UCM-palA10101402 in anterior (C1), left lateral (C2) and posterior (C3) view, UCM-palA10101403 from Riba-6 in lateral (D1), ventral (D2), and posterior (D3) view. E: Rib fragments UCM-pal 20031506 from Riba-2. F: Fragment of nothosaur? humerus UCM-palC20031501 from Riba-2 in anterior (F1), posterior (F2) and lateral (F3) views. G: Placodont tooth UCM-pal 10101404 from Riba-5. H: Skull fragment of placodont UCM-pal20031501 from Riba2. I-J: Fragments of placodont quadrate UCM-palVD28101401, UCM-palC20031507 from Riba-2. K: articular of the quadrate UCM-palVD28101402 from Riba-3. L-Q: Fragments of placodont osteoderms UCM-palA10101406, UCM-palA10101407, UCM-pal170100 from Riba-5 in dorsal, UCM-palC20031500. R: Fragment of cyamodontoid placodont plastron plate UCM-palV15071701 from Riba-4 in dorsal view. Scale bar: 0,5 cm for G, 1 cm for A-E; 1 cm for H-R.

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Fig. 8. A: Indeterminate bone remain UCM-pal10121401 from Sienes. B: Sauropterygian ulna UCM-palC21031505 from Riba-2. C: Distal Euriapsida ulna? UCM-palC20031507 UCM-palS20031501 from Sienes. D-F: Articular surfaces of ribs UCM-pal C21031503 from Riba-2. G: Rib fragments UCM-pal 20031506 from Riba-2. H: Mandible fragment of reptile UCM-palVG25031528 from Riba-4. I: Isolated intervertebral disk UCM-palA10101401 from Riba-5. Scale bar: 1 cm for A-F, 0,5 cm for G, 2 cm for H and 1 cm for I.

small caudal vertebra (Fig. 7C and D), which possibly corresponds with nothosaurs has appeared in Riba-2. One of them is 1 cm long and 1 cm width, with the articular facets of the caudal centrum amphicoelus and circular to quadrangular contour (Fig. 7C). The middle part of its centrum is constricted in ventral view. Another bad preserved platycoelus small caudal vertebra shows 1 cm long and 1 cm width (Fig. 7D). An incomplete and relatively big fragment of humerus (Fig. 7F) has been also found in Riba-2 and, although it is broken and bad preserved, the change of thickness on the ventral surface can be distinguished, which results in a triangular cross-section of the bone. This humerus fragment shows smooth and oblate ventral side, being its maximum width of 3 cm.

6.3.2. Placodonts In the Riba the Santiuste fossil sites, the remains of placodonts are abundant (but in less proportion than those of nothosaurs) and are mainly represented by both carapace and plastron plates. On these sites, it is possible to identify teeth (Figs. 4 and 7G), skull fragments (Fig. 7H), fragments of quadrates (Fig. 7I–K) and a high quantity of osteoderms and fragments of plastron plate, both of cyamodontoid and non-cyamodontoid placodonts (Fig. 7L–Q). Some of them are mainly isolated fragments with polygonal bony plates (Fig. 7R). Some rounded and flattened teeth of placodonts are still embedded in the rock (Fig. 4) and damaged (Fig. 4G and H). In these teeth, the enamel is almost 1mm-thick and shows numerous long

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and irregular radial wrinkles on its inner surface. Other morphotypes of small size (maximum diameter of 0,8 cm) are rounded and have a central elevation with a pointed end, as it can be inferred from the internal surface (Fig. 7G). These features are characteristic of placodont teeth (Romer, 1966; Rieppel, 2002). Placodont teeth with similar features of the first morphotypes were described in the Hesperian Triassic (Alafont, 1992; Pinna, 1990; Niemeyer, 2002). A skull fragment of 0,6 thick cm has been recovered in Riba-2. This is very bulky and massive, which is characteristic of placodont skull (Mazin, 2001). Some fragments of placodont quadrate have been found together (Fig. 7I and J), and the area where it articulates with the articular can be observed (Fig. 7K). One of the quadrates is 3,3 cm long and 2,8 cm wide (Fig. 7I). The other quadrate is incomplete and is 2,4 cm in width (Fig. 7J). Placodont quadrate is a well-developed bone, vertically placed in placodonts (Romer, 1966). Regarding the osteoderms, the most common osteoderm morphotype from the Riba de Santiuste area corresponds to subcircular (Fig. 7L) or irregular osteoderms (Fig. 7M). Their maximum length is about 3,5 cm. The features of these osteoderms seem to correspond to non-cyamodontoids placodonts. It can also be observed that another incomplete fragments of plates showing interdigitated sutures between osteoderms (Fig. 7N–R). Some fragments of plates (maximum diameter 4,5 cm and thickness of 4 mm) show hexagonal osteoderms (Fig. 7R). The interdigitated sutures between osteoderms can be well distinguished. The presence of interdigital sutures are typical of osteoderms (Rieppel, 2002). The hexagonal osteoderms are the basic morphogenetic unit of the cyamodontoid placodont caparace (Rieppel, 2002). Placodont hexagonal osteoderms have described in different points of the Iberian Peninsula (Alafont, 1992; Sanz et al., 1993; Niemeyer, 2002; Miguel Chaves et al., 2017). 6.3.3. Other vertebrate remains Some vertebrate remains are difficult to assign with more precision. An indeterminated bone (Fig. 8A) of Euriapsida has

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been collected at Sienes. A Sauropterygian ulna have been found in Riba-2. It shows 2,4 cm of maximum width, and it is dorsoventrally flattened, with clearly expanded distal end (Fig. 8B). A fragment of smaller but wider distal sauropterygian ulna have been found in Sienes (Fig. 8C). Some articular surfaces of ribs (Fig. 8D–F) and several rib fragments (Fig. 8G) of undetermined Sauropterygia have also been found. Some large fragmentary remains have not been identified with precision, as some of them are bigger than the sauropterygian remains here collected. These elements include a mandible remains from the Riba de Santiuste Anticline. This part of mandible consists in a fragment of a lower jaw, which does not preserve a single tooth. The fragment is 3,5 cm in height and 2 cm thick and shows subtriangular shape (Fig. 8H). In the studied area, an intervertebral disk (Fig. 8I) has been also discovered. This disk consists of an internal mould that could have formed between two vertebrae. Its diameter is of 5 cm, with discoidal-subcircular shape and plane-convex in lateral view (the anterior surface is flat and the posterior surface is convex). On the anterior facet, successive concentric lines can also be observed (Fig. 8I.1). This intervertebral disk is bigger than other vertebrae found in the area attributed in most of the cases to nothosaurs and placodonts. 6.4. Vertebrate traces In Riba de Santiuste area, blocks of sandstone with ripple marks reveal vertebrate traces preserved as impressions on the substrate and as natural casts (Fig. 9). These traces consist mostly in elongated, striated and parallel scratch marks. Some specimens show up to three parallel grooves and some of them are narrow sinuous scratch marks from less than 1 to 3 mm in width and up to 10 cm in length. There are also small impressions with teardrop morphology that have pointed ends what indicate the presence of tracemakers whose feet had small claws. These traces without heel impression seem to indicate a tracemaker that floated in the water. Indeed, all these traces can be interpreted as if they had been

Fig. 9. Ripple marks with unidentified swim traces from the Characichnos ichnofacies (Riba de Santiuste tracksite, Guadalajara, Spain). Three parallel and narrow sinuous scratch marks (A). Small isolated impressions with teardrop morphology (B). Ripple marks with claw marks (B-C).

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7. Discussion

before and after burial. According to Thomson and Droser (2015), Triassic deltas and their palaeoenvironments were favorable habitats for functionally amphibious reptiles and, simultaneously, in these times, there were few animals living in the sediment mixing it up, and so the muds became firm and cohesive providing ideal conditions for preservation. This is what seems to have happened at the Riba de Santiuste tracksites. These traces occur in firm, but not lithified sediments, such as muds and silts in marine intertidal and shallow subtidal zones. The firm grounds may develop in low energy situations such as salt marshes, mud bars, of high intertidal flats, or in shallow marine environments where erosion has stripped off superficial unconsolidated layers of sediment. The Glossifungites ichnofacies is characterized by domichnia (Glossifungites and Thalassinoides) and sometimes plant root penetration structures.

7.1. Dating the sites

7.3. Vertebrate remarks

Regarding the age of the materials, in the top of the Royuela Formation, Sopeña (1979) described some pollen assemblages that were common in the Carnian, and García-Gil (1990, 1991) between the Ladinian and the Carnian. For this reason, some subsequent works referred to the Middle Triassic vertebrate remains of tetrapod of Riba de Santiuste positioned its fossil sites between the Ladinian and the Carnian (Alafont, 1999). Nevertheless, recent works about these types of triassic pollen assemblages of the Tethyan realm (Hochuli et al., 2015) exposed that some of these palynomorphs classically attributed to Carnian were present in the Ladinian, being their range actualized. The precise stratigraphic position in which the vertebrate remains here studied have been collected with the previously mentioned bivalves, and after the nautiloid revision of Picardiceras sopegnai from Riba de Santiuste made by Pérez-Valera et al. (2017), allows assigning these remains to the Upper Ladinian (Fig. 2).

Since the specific taxonomic assignment of some vertebrate remains is still pending, several general classifications may be given. Nothosaur teeth previously described show characteristic folding of the enamel (Fig. 6A–D). The folding of the enamel is a character shared by most of the Triassic sauropterygians (Sanz, 1980; Alafont, 1992). These teeth resemble to those assigned to Nothosauridae, in which the morphology of the teeth is very variable, even in the same individual (Sanz, 1980). The clade Nothosauroidea (Pachypleosauria + Simosauridae + Nothosauridae) shows this type of ornamentation, which is not present in other reptiles, such as pistosaurs (Diedrich, 2013). Nevertheless, in pachypleosaurs the dentition is homodont, with a straight crown and wide base (Sanz, 1980). The Simosaurus teeth are very distinctive because they show a wide and conic crown, which is well differenced of the base of the tooth (Sanz, 1984; Rieppel, 1994). Therefore, the teeth here studied (Fig. 6A-D) can be attributed to Nothosauridae. The neural arch of the first thoracic nothosaur vertebrae (Fig. 6F), and the isolated nothosaur neural arch (Fig. 6G) previously mentioned do not present infraprezygapophyses and infrapostzygapophyses in the neural arch, and they are not compatible with Simosauridae, although they are compatible with Nothosauridae (Rieppel, 2000). Nevertheless, between the nothosaur remains here studied, some vertebrae centra show a characteristic butterfly-shaped (sensu Rieppel, 1994) (Fig. 10). This feature has been argued to identify vertebral centra of Simosaurus (Sanz, 1980, 1984). In other close Triassic outcrops, cf. Simosaurus appear (Miguel Chaves et al., 2016). In Simosaurus, the dorsal surface of the centra is copiously withered providing a characteristic butterfly-shaped platform for the articulation with the neural arch. This platform, increasing in width along an anteroposterior gradient, is transverse by the longitudinal neural canal forming a longitudinal groove on the centrum, which is somewhat broader and deeper than in Nothosaurus. The neurocentral suture remains open in sauropterygians. The neural arch frecuently dissociates from the centrum in pachypleosaurs, simosaurs and nothosaurs in the cervical and dorsal region of the vertebral column. This dissociation reveals a broadered facet formed by the dorsal surface of the centrum to receive the pedicles of the neural arch. This structure is also present in pachypleosaurs, but the pachypleosaurs vertebrae use to present dimensions of around 4–15 mm, according to Alafont (1992, 1999). Hence, the vertebral centrum UCM-palV18101405 (Fig. 7B) being too small (14 mm) cannot be excluded of pachyplesosaurs. Alafont (1999) mentioned the possible presence of pachypleosaurs in the Riba de Santiuste Anticline based on some small bad preserved vertebral centra. In 2009, some sauropterygian remains from the Keuper of El Atance (Guadalajara) were preliminarily referred to the genus Simosaurus (Quesada et al., 2009). This attribution was revised,

produced by animals swimming in shallow water in such a way that the tip of the toes touches the sediment surface while the body and the tail float (swim traces). These traces can be assigned to the Characichnos ichnofacies (sensu Hunt and Lucas, 2007) that is characterized by parallel scratch marks and fish swimming trails (Undichna) from shallow lacustrine environments. The original orientation of some of the blocks with vertebrate traces is unknown, but the direction of the elongated traces is oriented perpendicularly to the ripple marks. Unfortunately, to date there are no pes or manus prints evidences to allow us to recognize the potential vertebrate tracemakers. To characterize the Middle Triassic ichnocoenose from this area is one of the ongoing research aims.

7.2. Sedimentary palaeoenvironment The Riba de Santiuste area is an exceptional place due to the excellent preservation of sedimentary structures and by the information that these structures provide for the reconstruction of sedimentary environments (García-Gil,1990; Sánchez-Moya et al., 2015). Here, some questions about the palaeoenvironmental implications of some of the studied faunas have been highlighted. The presence of Lingula can be related to the existence of shallow marine environments, with a wide range of variability in the salinity of its waters (Prats et al.,1987). The presence of Pseudocorbula seems also be related to shallow marine palaeoenvirontments (García-Gil, 1991). This is an infaunal bivalve, which behaves as an opportunistic specie and generally is represented by a large number of small individuals. It could be interpreted as a biological response to unstable environments or very low ecological requirements (Márquez-Aliaga et al., 1986; Márquez-Aliaga and García-Gil, 1991). The main part of the bones appear in marly levels that also include presence of the shallow marine to lagoonal Pleuromya sp. and Lingula sp (Fig. 2). In fact, Sauropterygians were animals exclusively marine (Rieppel and Wild, 1996), but they could live in coastal marine restricted environments (Rieppel and Hagdorn, 1998; Calvet and Tucker, 1995). Above the levels rich in bone remains, sandy levels with different types of ripple marks with vertebrate traces appear (Fig. 2). The presence of drag marks is associated with displacement rims, and indicates the high degree of plasticity and water content of the sediment at the time of track production, as well as the swimming behavior of various Triassic tetrapods. The preservation of these scratch marks required a firm and semicohesive substrate in order to maintain track morphology detail

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Fig. 10. Dorsal centrum of Nothosauroidea UCMpalV10101400 from the Middle Triassic of the Riba de Santiuste area.

and the remains from El Atance were attributed to an undetermined taxon that could be close to Simosaurus (Miguel Chaves et al., 2014b). In the same way, Miguel Chaves et al. (2016) identified Simosaurus in the Carnian of Teruel (Spain). Some vertebrae here studied seem to correspond to Simosaurus. Alternatively, these remains correspond to a taxon close to Simosaurus. In any case, the presence of this taxon (or a taxon close to Simosaurus) is here documented in the Upper Ladinian of Riba de Santiuste anticline. The humerus bone previously described here is incomplete (Fig. 7F) (possibly broken by the curvature zone). Curved humerous, straight preaxial angle and postaxial concavity is a diagnostical feature of nothosaurs (Romer, 1966; Storrs, 1991). According to Rieppel (1994), the sauropterygian humerus appears “curved” in adult individuals due to a distinct angulation along its anterior margin and an evenly concave posterior margin. Thus, this fragment of bone could correspond to a nothosaur humerous, but it is not well preserved to could describe more features and to attribute with precision. Most of the placodont remains here recovered are too fragmentary to be identified at specific or even generic level. In the area, hexagonal osteoderms appear. Hexagonal osteoderms (such as Fig. 7R) are the basic morphogenetic unit of the cyamodontoid placodont caparace (Rieppel, 2002). In those cyamodontoids with a plastron (Henodus, Placochelys and Psephosauriscus), osteoderms also fused together along the sides of the body to form a lateral wall linking the plastron and the carapace. These osteoderms on the dorsal surface of the animal were tightly sutured together to form a carapace. Until the present paper, only non-cyamodontoid osteoderms were known in the Riba de Santiuste area (Alafont, 1999, Berrocal-Casero and Castaninha, 2015). Among the remaining fossils collected in this area, an intervertebral disk of a big reptile (UCM-palA10101401) (Fig. 8I) should be highlighted. This disk consists of an internal mould formed between two vertebrae. The same bone is too big (5 cm) compared to other vertebrae found in the area attributed to sauropterygians. The size of this intervertebral disk is compatible to archosaurs, such as Triassic rauisuchians. Close to Riba-6 (Fig. 2) (in the western part of the Riba de Santiuste Anticline) there are some rauisuchian tracks and trackways already described (Meléndez and Moratalla, 2014). Probably some undetermined bone remains here represented correspond to rauisuchian, being the indicated tracks weak evidences. Because Triassic archosaur reptiles like rauisuchians are extinct reptiles, it is only possible to reconstruct the intervertebral space by direct comparison to extant, analogous and phylogenetically related taxa. The procoelous vertebral bodies of extant crocodylians are connected by synovial joints, consisting of an outer articular capsule and an inner cavity (Witzmann et al., 2014). To found new evidences that support these discover is one of the research aim.

8. Conclusions The fossil sites located in the Riba de Santiuste area are described in this paper, adding new data to the palaeontological record from the Middle Triassic of the Province of Guadalajara (Spain). These fossil sites are more diverse and abundant than previously recognized. Different taxa of plants, brachiopods, bivalves and abundant sauropterygian (nothosaurs and placodonts) remains have been identified. The Nothosauroidea vertebrate remains are the most common in the area. The presence of Simosaurus or a taxon close to Simosaurus is documented in the Upper Ladinian of Riba de Santiuste anticline. Placodont osteoderms are also frequent and attest the occurrence of non-cyamodontoid and cyamodontid placodonts. Until now, only non-cyamodontoid osteoderms were known in this area, so the presence of part of a plastron of cyamodontoid placodont plastron plates is remarkable. Nevertheless, the most interesting discovery correspond to those bones that do not seem to correspond to sauropterygians, like the big fragment of mandible and the big mould of intervertebral disk of a reptile, whose size could be compatible to archosaur remains. The vertebrate bones here studied show an exceptional preservation of their microstructure. Consequently, this work contains a preliminary analysis about the exceptional preservation of these fossil vertebrate remains, and future additional studies promise interesting taphonomical and palaeobiological interpretations. The presence in sandy levels of swim traces with displacement rims indicates the high degree of plasticity and water content of the sediment at the time of track production on coastal intertidal to supratidal environments. These unidentified traces from the Characichnos ichnofacies point to the existence of vertebrates with a high capacity of aquatic locomotion during the Middle Triassic. As a whole, the Riba de Santiuste area provides a particular scenario to reconstruct the Upper Ladinian ecosystems. Though the results presented here are still preliminary, a detailed taxonomic study of these new remains, and a deeper exploration of the sites can provide new information about the flora and fauna that lived in this area during the Middle Triassic. Acknowledgements We are very grateful to Dr. Fernando Barroso-Barcenilla from Universidad de Alcalá for all his help and support during the realization of this work. To Felipe Merino from Riosalido. We gratefully acknowledge the comments from the anonymous reviewers and the Editor that have helped to improve the manuscript. This work is developed within Predoctoral Research Training Grant CT45/15-CT46/15 from the UCM, and is a contribution to Research Projects CGL2015-66604 and CGL201568363 from the Spanish Ministerio de Economía y Competitividad (Economy and Competitiveness Ministry).

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Appendix A SYSTEMATIC PALAEONTOLOGY Plants ?Scolopendrites sp. Brachiopods Lingula Brugiére, 1791 Lingula tenuissima Bronn, 1837 Bivalves Pseudocorbula Philippi, 1898 Pseudocorbula gregaria Münster in Goldfuss, 1838 Costatoria Waagen, 1907 Costatoria killiani (Schmidt, 1935) Lyriomyophoria Kobayashi, 1954 Lyriomyophoria cf. sublaevis (Schmidt, 1935) Sauropterygians Nothosaurs Sauropterygia Owen, 1860 Eosauropterygia Rieppel, 1994 Nothosauridae Baur, 1889 Nothosaurus Münster, 1834 Simosauria Rieppel, 2000 Simosauridae, Huene, 1948 Simosaurus Meyer, 1842 Placodonts Sauropterygia Owen, I860 Placodontiformes Neenan, Klein and Scheyer, 2013 Placodontia Cope, 1871 Cyamodontoidea Nopcsa, 1923 Archosaurs Rauisuchia von Huene, 1942 References Alafont, L.S., Sanz, J.L., 1996. Un nuevo Sauropterigio (Reptilia) en el Triásico de la Sierra de Prades (Tarragona). Cuadernos de Geología Ibérica 20, 313–329. Alafont, L.S., 1992. Notosaurios y Placodontos (Reptilia) del Triásico Medio de Bienservida Villarrodrigo. Instituto de Estudios albacetenses de la Excma. Diputación de Albacete, Albacete (129 pp.). Alafont, L.S., 1999. Reptiles del Triásico de Castilla-La Mancha. In: Aguirre, E., Rábano, I. (Eds.), La huella del pasado. Fósiles de Castilla-La Mancha. Serie Patrimonio Histórico Arqueología, Toledo, pp. 143–159. Almela, A., Llopis Lladó, N., 1947. Explicación de la Hoja no 392 DE Sabadell. Mapa Geológico de España 1:50.000. IGME, Madrid (31 pp.). Bauzá, J., 1955. Notas paleontológicas de Mallorca: sobre el hallazgo del Nothosaurus en el Trías. Boletín de la Sociedad de Historia Natural de Baleares 1, 87. Berrocal-Casero, M., Castaninha, R., 2015. Nuevos hallazgos de vertebrados triásicos en el anticlinal de Riba de Santiuste (Guadalajara, España). In: Domingo, L., Domingo, S., Fesharaki, O., García Yelo, B., Gómez Cano, A.R., Hernández-Ballarín, V., Hontecillas, D., Cantalapiedra, J.L., López Guerrero, P., Oliver, A., Pelegrín, J., Pérez de los Ríos, M., Ríos, M., Sanisidro, O., Valenciano, A. (Eds.), Current Trends in Paleontology and Evolution. XII EJIP Conference Procedings, Madrid, pp. 58. Calvet, F., Tucker, M.E., 1995. Mud-mounds with reefal caps in the Upper Muschelkalk (Triassic), eastern Spain. In: Monty, C.L.V., Bosence, D.B., Bridges, P., Pratt, B. (Eds.), Mud Mounds: Origin and evolution. Blackwell Scientific Publications. International Association of Sedimentologists, Special Publication 23, Oxford, pp. 311–333. Demathieu, G., Ramos, A., Sopeña, A., 1978. Fauna icnológica del Triásico de extremo noroccidental de la Cordillera Ibérica (Prov. de Guadalajara). Estudios geológicos 34, 175–186. Diedrich, C.G., 2013. The oldest Subaquatic Flying reptile in the Word-Pistosaurus longaevus Meyer, 1839 (Sauropterugia) from the Middle Triassic of Europe. New Mexico Museum of Natural History and Science. Bulletin 61, 169–215. Ellenberger, P., Villalta, J.F., 1974. Sur la présence d’un ancêtre probable d’oisseau dans le Muschelkalk supérieur de Catalogne (Espagne). Note préliminaire. Acta Geologica Hispanica 9, 162–168.

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