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Vertebrate fossils from the Adamantina Formation (Late Cretaceous), Prata paleontological district, Minas Gerais State, Brazil
Geobios 39 (2006) 319–327 http://france.elsevier.com/direct/GEOBIO/
Original article
Vertebrate fossils from the Adamantina Formation (Late Cretaceous), Prata paleontological district, Minas Gerais State, Brazil Vertébrés fossiles du Crétacé supérieur de la Formation Adamantina, district paléontologique de Prata, État de Minas Gerais, Brésil Vertebrados fósseis da Formação Adamantina (Neocretáceo) do Distrito Paleontológico do Prata, Estado de Minas Gerais, Brasil Carlos Roberto A. Candeiro a,b,*, Adriano R. Santos a, Thomas H. Rich c,d, Thiago S. Marinho a,b, Emerson C. Oliveira a a
Museu de minerais e rochas, Universidade federal de uberlândia (UFU), Avenida João Naves de Ávila 2160, 38408-100 Uberlândia, MG, Brazil b Laboratório de macrofósseis, departamento de geologia, Universidade federal do Rio de Janeiro (UFRJ), avenida Brigadeiro Trompowski, s/n, Ilha do Fundão, 21949-900 Rio de Janeiro, RJ, Brazil c Museum of Victoria, PO Box 666E, Melbourne, Victoria, Australia d School of geosciences, PO Box 28E, monash University, Victoria 3800, Australia Received 11 May 2004; accepted 21 October 2004 Available online 22 May 2006
Abstract In this contribution is given a preliminary up-to-date annotated list of all fossil vertebrates from the Turonian–Santonian Adamantina Formation, Bauru Group where it occurs in the Prata paleontological district which is located 45 km to the west of Prata in Minas Gerais State, Brazil. The Adamantina Formation is a reddish sandstone in the Triângulo Mineiro region. These fluviolacustrine sediments were deposited in a semiarid environment. Three fossil vertebrate sites occur in the Prata paleontological district. The diversity of vertebrates in the Adamantina Formation is modest, and its components comprise a mixture of typical austral Gondwana taxa (such as abelisaurids, Aeolosaurus) and boreal Gondwana taxa (such as Carcharodontosauridae). The absence of Laurasian taxa in the upper part of the Bauru Group is noteworthy. Excepting some turtles, crocodylians, and one titanosaurid, most of the specimens discovered in this Group are based on fragmentary and isolated remains, which make it difficult to correctly identify the fossils. For this reason, many of the taxa have only been identified in a preliminary manner. Despite this drawback, the dinosaurs are typical Gondwana forms with no evidence of Laurasian affinities. This is concordant with the idea that the Laurasian dinosaurs entered South America at the end of the Late Cretaceous; i.e. after the Turonian–Santonian, the age of the Adamantina Formation. © 2006 Elsevier SAS. All rights reserved. Résumé La liste des vertébrés fossiles est mise à jour dans la Formation Adamantina datée du Turonien-Santonien affleurant dans le district paléontologique de Prata à 45 km à l’est de Prata (Minas Gerais, Brésil). La Formation Adamantina est composée de grès rougeâtres dans la région du Triangle Minier. Les sédiments fluviolacustres se sont déposés dans un environnement semi-aride. Trois sites à vertébrés fossiles sont connus dans le district paléontologique de Prata. La diversité des vertébrés de la Formation Adamantina est réduite et comprend un mélange de taxons typiques du Gondwana austral (comme des Abelisauridés, Aeolosaurus) et des taxons du Gondwana boréal (comme des Carcharodontosauridae).
* Corresponding
author. E-mail address: [email protected] (C.R.A. Candeiro).
0016-6995/$ - see front matter © 2006 Elsevier SAS. All rights reserved. doi:10.1016/j.geobios.2005.10.003
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L’absence de taxons laurasiatiques dans la partie supérieure du Groupe Bauru est remarquable. Excepté quelques tortues, des crocodiliens et un titanosauridé, la plupart des spécimens découverts dans ce Groupe Bauru sont représentés par des restes fragmentaires et isolés. Pour cette raison, seules des identifications préliminaires sont proposées. Toutefois, les dinosaures sont typiques du Gondwana sans évidence d’affinité Laurasienne. Ceci est en accord avec l’hypothèse que les dinosaures laurasiens ne seraient arrivés en Amérique du Sud qu’à la fin de Crétacé supérieur, c’est-à-dire après le Turonien-Santonien, âge de la Formation Adamantina. © 2006 Elsevier SAS. All rights reserved. Resumo Na presente contribuição é apresentada uma listagem preliminar de todos os fósseis de vertebrados do Distrito Paleontológico do Prata (Formação Adamantina, Turoniano-Santoniano, Grupo Bauru). As rochas da Formação Adamantina são compostas por arenitos avermelhados que afloram na região do Triângulo Mineiro. Esses sedimetnos de origem fluvio-lacustre foram depositados em um ambiente semi-árido. São conhecidos três sítios de vertebrados fósseis que ocorrem no Distrito Paleontológico do Prata. A diversidade de vertebrados na Formação Adamantina é modesta sendo representados por uma mistura típica de taxa austrais do Gondwana (abelisaurídeos e Aeolosaurus) e boreais (carcarodotontosaurídeos). A ausência de taxa laurasianos na parte superior do Grupo Bauru é notável. Exceto pela presença de tartarugas, crocodilianos e um titanossaurídeo a maioria dos espécimes descobertos nessa unidade geológica é baseada em restos fragmentários e isolados os quais são de difícil identificação. Por essa razão, a maioria desses taxa têm sido somente identificados de forma preliminar. Considerando essa desvantagem, se pode afirmar que os dinossauros do Prata são tipicamente de formas gondwânicas com nenhuma evidência de formas laurasianas. Isso é concordante com a idéia de que os dinossauros laurasianos entraram na América do Sul somente no final do Neocretáceo, ex. depois do Turoniano-Santoniano, que é a idade da Formação Adamantina. © 2006 Elsevier SAS. All rights reserved. Keywords: Late Cretaceous; Brazil; Crocodiles; Dinosaurs; Turtles Mots clés : Crétacé supérieur ; Brésil ; Crocodiliens ; Dinosaures ; Tortues Palabras-chaves: Neocretáceo; Brasil; Crocodilos; Dinossauros; Tartarugas
1. Introduction Since the beginning of the last century, numerous specimens of fossil vertebrates have been collected from continental Cretaceous rocks of the Adamantina Formation, Bauru Group, in the Bauru Basin, Triângulo Mineiro region, Minas Gerais State. In the same area of Minas Gerais State, the Marília Formation (Ponte Alta and Serra da Galga Members) also has yielded fossil vertebrates. Both formations have produced faunas consisting primarily of fishes, turtles, crocodylians, and dinosaurs. All of these fossils occur in sandstones deposited in braided river channels. A large quantity of fossil bones has been found in the continental Cretaceous rocks exposed in the Prata paleontological district of the Triângulo Mineiro region of Minas Gerais State, Brazil (Fig. 1; Goldberg et al., 1995a, 1995b; Silva et al., 2001; Marinho, 2003; Candeiro et al., 2003; Marinho et al., 2003). For this reason, the Prata paleontological district, located 45 km west of the town of Prata, is known as one of the most important fossil locations, as it contains abundant remains of sauropod and theropod dinosaurs as well crocodylians and turtles. Many authors (Soares et al., 1980; Suguio and Barcelos, 1983; Barcelos, 1984; Candeiro, 2002) assign the sediments of Prata paleontological district to the Adamantina Formation (Bauru Group), which was dated as Turonian–Santonian in age (Dias-Brito et al., 2001). This unit is exposed at the Serra da Boa Vista Hill, in the vicinity of Prata. Some of the richest Cretaceous fossil vertebrate localities in Central Brazil occur in the Adamantina Formation. Many of the Adamantina Formation sites in the Prata paleontological
district have been known since the 1920s (Price, 1961). Owing to a lack of reliable lithological and paleontological data, the geological ages of these sites are not well established. The Adamantina Formation was formally proposed by Soares et al. (1980). The unit, 2–20 m thick, consists of rose to brown fine grained, cross-bedded sandstone. The type section of this formation was in the town of Adamantina, São Paulo State. In Triângulo Mineiro, the Adamantina Formation is the basal lithostratigrafic unit of the Bauru Group and is widely exposed in the area. In the Prata paleontological district, Triângulo Mineiro (Fig. 1), three fossil vertebrate sites occur in the Adamantina Formation. These three fossil sites represent the best record of Late Cretaceous vertebrates in the Minas Gerais State (Brazil). This makes those sites some of the most important when discussing the fossil record of Late Cretaceous in Minas Gerais State. The vertebrates reported here are from the Adamantina Formation near Prata, and belong to the following groups: abelisaurs, carcharodontosaurs, Aeolosaurus, and titanosaur dinosaurs, turtles, and crocodylians. More is known about the dinosaurs than any other group from the Prata paleontological district. The paleontologist Llewellyn Ivor Price first reported to the Departamento Nacional de Produção Mineral fragmentary dinosaur bones in 1940. The fossils were transferred to Rio de Janeiro (Price, 1961). Since then, there have been numerous fossil collecting trips to the Prata paleontological district that have yielded new dinosaurs and other vertebrate fossils (Silva et al., 2001). However, detailed stratigraphic studies based on dinosaur remains were not attempted.
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Fig. 1. Location of the Prata paleontological district, and geographic distribution of the Cretaceous fossiliferous location.
2. Geological setting The Adamantina Formation was defined by Soares et al. (1980) and is known in the following states of Southeast Brazil: Goiás, Mato Grosso do Sul, Minas Gerais and São Paulo. These authors regarded it as part of the Bauru Group, which occurs in the Paraná Basin. Based on variation in the regional lithology, Barcelos (1984) divided the Adamantina Formation into two units: the Araçatuba and São José do Rio Preto Members. The Prata paleontological district is currently regarded as formed by rocks of the Bauru Group (Late Cretaceous) (Fig. 2). In the Triângulo Mineiro region, the Adamantina,
Marília and Uberaba formations sensu Fernandes and Coimbra (1996) form part of Bauru Group. These rocks overlay the basalt layers of the Serra Geral Formation. Goldberg and Garcia (2000) described the Adamantina Formation (Fig. 3) in the Prata paleontological district as very fine to fine grained, well-sorted, cross-bedded red sandstones. Furthermore, these authors recognized intraformational conglomerates and subordinate red shales, which are massive or laminar. The top of this unit is characterized by the interbedding of (1) conglomerates, (2) fine- to medium-grained crossbedded sandstones and (3) abundant nodular and horizontal carbonate concretions, which coarsen and thicken upward.
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Fig. 2. Geological map of the Bauru Group (Upper Cretaceous) in the Triângulo Mineiro region, Minas Gerais State, Brazil (modified de Fernandes and Coimbra, 1996).
Von Huene (1927, 1939) regarded the Adamantina Fm as Senomanian based on a correlation made between the turtle Najadochelys and the sauropod “Titanosaurs australis” with similar taxa recorded in northern Patagonia, Argentina. Based on ostracods and caryophytes, Dias-Brito et al. (2001) considers the age of this Formation to be Turonian–Santonian (92–83 my). 3. Vertebrate paleontology
Fig. 3. Bauru Group lithostratigraphic chart in Prata area (modified from Suguio and Barcelos, 1983).
The Late Cretaceous sequence of the Prata paleontological district contains fossil remains of crocodylians, dinosaurs and turtles (Table 1; Silva et al., 2001; Marinho, 2003; Albuquerque et al., 2003; Marinho et al., 2003; Moraes et al., 2003). The fossil occurrences are in hilly areas located west of Prata (Fig. 1). Because of the fragmentary nature of the fossils collected thus far, they have not been identified to a refined taxonomic level except the genus Aeolosaurus.
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Table 1 Vertebrate fauna of the Adamantina Formation from Prata paleontological district. See footnotes for source references included. 1 Goldberg et al. (1995a, 1995b), 2 Silva et al. (2001), 3 Marinho (2003), 4 Albuquerque et al. (2003), 5 Candeiro et al. (2003), 6 Marinho et al. (2003), 7 Moraes et al. (2003), 8 Henriques et al. (2002), 9 Almeida et al., 2003 (in press) Taxa
Vertebrata Vertebrata indet 1–7 Reptilia Chelonia indet. 2 Crocodylomorpha indet. 2 Dinosauria Sauropoda Titanosauria 2–8 Aeolosaurus 9 Theropoda Theropoda indet. 3-7 Abelisauridae 3, 7 Carcharodontosauridae 3
Location 1 Boa vista hill GPS. 19°27′26.0″S and 49°14′42.6″W.
Location 2 Outskirt GPS. 19°26′21.0″S and 49°15′41.3″W.
Location 2 “Idelmo Bramh farm” GPS. 19°26′31.8″S and 49°14′27.8″W.
x
x
x
x x
x x x x x
Fig. 4. Dinosaur remains from Prata paleontological district. A, labial view, B, lingual view Abelisauridae tooth (MMR/UFU-PV 0006); C, labial view, D, lingual view, Carcharodontosauridae tooth (MMR/UFU-PV 005); E, labial view, F, lingual view, Theropoda tooth (MMR/UFU-PV 007). Bar scale represent 30 mm. G, lateral view, Titanosauria caudal vertebrae (MMR/UFU-PV 0001); H, I, lateral view, Titanosauria ribs. Bar scale A, B, C, D, E, F bar scale = 30 mm; G = 10 mm; H, I = 50 mm.
3.1. Remarks about the dinosaurs of the Prata district Dinosaurs are the best-known and most diverse taxa from Prata Site. This material is housed mainly at MMR and UFRJ-DG and briefly commented here.
Abbreviations: MACN, Museo Argentino de Ciencias Naturales, Buenos Aires, Argentina; MUCPV-CH, Museo de la Universidad Nacional de Comahue, El Chocon collection; MMR/UFU-PV, Museu de Minerais e Rochas, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil;
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RTMP, Royal Tyrrell Museum of Palaeontology, Drumheller, Canada; UFRJ-DG-R, Departamento de Geologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil, fossil reptilian collection. 3.1.1. Systematic paleontology Suborder THEROPODA Marsh, 1881 ABELISAURIA Novas, 1992 Family ABELISAURIDAE Bonaparte and Novas, 1985 Material: (MMR/UFU-PV 0006) (Fig. 4A, B). Locality: 2. Remarks: the Abelisauridae are represented by a single tooth (MMR/UFU-PV 0006) from locality 2 on the western side of the Prata paleontological district. This tooth was described recently by Marinho (2003). It lacked a root but the preservation of the crown is good. It is small (32 mm), with serrated anterior and posterior carinae, the denticles on the proximal part of the anterior carina are smaller than those on the distal part, and denticles on the middle are largest. All the denticles on the distal part are pointed toward the crown apex. The denticles on the proximal and middle part of the anterior carina are perpendicular to the crown apex. The denticles on both carinae are higher than wide. The denticles of the proximal and distal parts of the posterior carinae are the same size; those in the middle are larger. The cross-section of the tooth has the anterior face compressed and posterior face convex (MMR/UFU-PV 0006) has the labial and lingual faces more convex in cross-section nears the anterior edge and flatter posteriorly; the lingual face is also slightly concave proximodistally. The characters exhibited by the low crown tooth from MMR/UFU-PV 0006 clearly indicate that it represents an abelisaurid. Bonaparte (1996), Lamanna et al. (2002), Wilson and Upchurch (2003), and Candeiro et al. (2004) noted the presence of a low crown in the Abelisauridae (e.g. Aucasaurus garridoi, Carnotaurus sastrei, Rajasarus narmadensis) teeth and regarded it as a diagnostic character of the family. Candeiro et al. (2004) pointed that abelisaurid teeth are characterized by labial and lingual faces more convex in cross-section near the anterior edge and flatter posteriorly; the lingual face is also slightly concave proximodistally. The cross-section of the specimen (MMR/UFU-PV 0006) is exactly as in the Abelisauridae. Family CARCHARODONTOSAURIDAE Stromer, 1931 Material: (MMR/UFU-PV 005) (Fig. 4C, D). Tooth. Locality: 2. Remarks: Marinho (2003) recently described MMR/UFUPV 005, which has a labial side of the tooth that is convex on its more anterior portion and posteriorly flattened. As on the labial side, the anterior part of the lingual side is slightly convex, becoming posteriorly flattened. The posterior region of the lingual side bears acute wrinkles on the enamel, which are very well developed, on the proximal and medial region, but these vanish toward the crown tip. Each wrinkle is obliquely oriented with respect to the tooth margin, but bends along its length
away from tooth margin until its orientation is transverse with respect to the tooth’s long axis. The wrinkle then continues across the tooth surface as a horizontal band. The posterior denticles on the proximal and distal ends are equal, while the middle denticles are larger. The anterior denticles are smaller than the posterior ones. All the denticles of both carinae are perpendicular to the crown apex, and are rather higher than wide. The cross-section is chestnut-shaped. The outline of the tooth in lateral view is in the form of a rough isosceles triangle. The presence of wrinkles on a theropod teeth tooth crown has been considered as a diagnostic feature for Carcharodontosauridae (Carcharodontosaurus saharicus and Giganotosaurus carolinii) by many authors (Larsson, 1996; Sereno et al., 1996; Vickers Rich et al., 1999; Candeiro et al., 2004). In Giganotosaurus carolinii different forms of wrinkles occur (Candeiro pers. obsers.) which can be strong or subdued. These wrinkles may or may not be close to the crown border (e.g. Carcharodontosaurus and Giganotosaurus). The wrinkles on the crown of MMR/UFU-PV 005 are strong and similar to the wrinkles found in carcharodontosaurids. This specimen is mediolaterally compressed and thus quite similar to Carcharodontosaurus saharicus (Stromer, 1931) and the Giganotosaurus (MUCPV-CH-1 and casts of MACN S/N and RTMP 94.43.1, 94.43.2, 94.43.3, 94.43.4). The presence of carcharodontosaurids in the PPD is especially noteworthy as it represents the youngest record of this clade found to date (Turonian–Santonian). Previously, the youngest known records of carcharodontosaurids are from Cenomanian beds in Africa, Argentina and Maranhão State in Brazil. Carcharodontosaurid teeth from the MMR/UFU-PV 005 of Late Cretaceous age contrast with the osteological record of Carcharodontosauridae, which is mainly restricted to older parts of the Cretaceous (e.g. Albian–Turonian) of Africa and South America. Order THEROPODA indet. Material: (MMR/UFU-PV 0007) (Fig. 4E, F). Tooth. Locality: 2. Remarks: no family assignment could be made for MMR/ UFU-PV 0007, but there is no doubt that this specimen belongs to a theropod dinosaur as it is strongly labio-lingually compressed and shows denticles with great variation in size and shape throughout the carina. Their cross-sections are different from any of the known Gondwanan Theropoda, but it is important to note that the teeth of some Gondwanan dinosaurs are still unknown (Novas, 1997). TITANOSAURIA Bonaparte and Coria, 1993 Genus Aeolosaurus Powell, 1986 Aeolosaurus indet. Material: (UFRJ-DG 270-R). Caudal vertebra. Locality: 2. Remarks: the sauropods are the most common and abundant fossil vertebrate remains found in the region (Fig. 4G–I). Numerous postcranial bones represent them. Almeida et al. (2003, 2004) (UFRJ-DG 270-R caudal vertebra) (Fig. 5A–C)
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tion of this caudal vertebrate is a synapomorphic feature that allies it with the “Titanosauridae” (Bonaparte and Coria, 1993; Wilson and Upchurch, 2003). The heart-shaped posterior articular facet and wide prezygapophyses allow us to relate this vertebra to the taxa Gondwanatitan/Aeolosaurus. Recently, a titanosaurid (MN 5013-V) was recognized at the same locality (the Boa Vista Hill) (Table 1). However, Almeida et al. (2004) pointed out that the specimen lacked features of the Gondwanatitan/Aeolosaurus complex. Henriques et al. (2002) suggested that this fossil was a new taxon closely related to these genera. TITANOSAURIA indet Material: (MMR-UFU-PV 001). Caudal vertebrae. Locality: 2. Remarks: there are several fragments of disarticulated bones found in Adamantina Formation sediments in the Prata paleontological district that have not previously been attributed to the Titanosauridae (sensu Powell, 1986, 2003; McIntosh, 1990). These specimens are caudal vertebrae (MMR-UFU-PV 001; Fig. 4G) that are strongly procoelous, having “ball socket” posterior articular faces. According Powell (1986, 2003) and McIntosh (1990) among Titanosauria, titanosaurids developed anterior caudals with a deeply excavated anterior face much like a “socket” and a posterior articulation like a prominent “ball”.
Fig. 5. Aeolosaurus caudal vertebra UFRJ-DG 270-R. Lateral view (A), posterior (B) and anterior (C). Abbreviations: CN, neural canal; PRZ, postzigapophysis; PT, transverse process; PZ, postzygapophysy; SN, neural spine. Scale bar 50 mm.
and Henriques et al. (2002) reported the presence of titanosaurid sauropods. Almeida et al. (2003, 2004) recognized the titanosaurid genus Aeolosaurus, which was first described from the Late Cretaceous of Patagonia (Argentina) (Powell, 1986, 2003; Salgado and Coria, 1993; Salgado, 2000). Although this vertebra is almost complete, it did suffer some damage. This damage made it possible to observe the internal spongy composition (Fig. 5B) of the bone. The vertebral centrum is deep and relatively low, procoelous, and bears a heart-shaped anterior articular facet (Fig. 5C). The transverse process is well developed and positioned at the centro-neural suture. The base of the neural arch is positioned anteriorly in relation to the vertebral centrum. The neural canal is oval—the lateral diameter is the longer one. The neural spine is large and posteriorly oriented, showing a well-developed prespinal laminae (PRSL) (Fig. 5A). The spinoprezygapophyseal laminae are also well developed and both are joined to the base of the PRSL. The postzygapophysis is well marked. The haemal arch is straight and laterally compressed. Although its proximal region is fragmented, its Y-shaped nature is readily seen. The open haemal canal indicates that this caudal vertebra belongs to the Camarasauromorpha. Within that group, the procoelous condi-
3.1.2. Adamantina Formation fossil localities in the Prata paleontogical district Price studied the first fossil site in the Prata paleontological district in the 1950’s. However, it was only in 2002 that fossil localities in the Adamantina Formation were discovered in that area by researchers from the Universidade Federal de Uberlândia (Museu de Minerais e Rochas). Three fossil vertebrate sites in the Adamantina Formation are mentioned in the literature (e.g. Albuquerque et al., 2003). The best-known vertebrate fossils of Adamantina Formation occur in the Prata paleontological district and are listed in Table 1. 4. Concluding remarks The fossils from the Prata paleontological district are all vertebrates mainly collected at the Boa Vista Hill fossil site, Locality 2. The best-known taxa from the Adamantina Formation are referred to the Abelisauridae, Carcharodontosauridae and Titanosauria (Aeolosaurus and Titanosauria indet.). Although the vertebrate fossil record of Prata District is currently poorly known, with few well-preserved specimens, many fragmentary remains have been found. Fossil localities are centered in the western parts of Prata municipality, and resemble the fauna from southern South America (Patagonia). The dinosaurs of the Prata District comprise two families of Gondwanan theropods (Abelisauridae and Carchadorodontosauridae), one genus of titanosaurs (Aeolosaurus). Single crocodilian and turtle records are reported in the literature from the Prata District. Their presence supports the earlier conclu-
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sions of Von Huene (1927, 1939) that correlated the fauna of Adamantina Formation with those found in the Late Cretaceous of Argentina or even those of Africa, India and Madagascar. Although only a few of the named Prata taxa have been fully reported, a picture is emerging which suggests a Gondwanan origin for the assemblage (Bonaparte, 1986). Carcharodontosaurs are common in the early Late Cretaceous in South America (Coria and Salgado, 1995; Leanza et al., 2004), but in the Prata District of Minas Gerais State a record of this group indicates that it possibly survived into the Late Cretaceous. Titanosaurs and abelisaurs dominate the Late Cretaceous in the Gondwana landmasses. They are found also in Late Cretaceous of the Prata District. Aeolosaurus is found not only in the Prata paleontological district but also in the Late Cretaceous of Argentina. Typical Laurasian taxa such as ornithischians have been widely documented in several Late Cretaceous units of Southern South America (e.g. Bonaparte et al., 1984; Salgado and Coria, 1996; De Valais et al., 2003; Novas et al., 2004). Because they are absent from earlier Turonian–Santonian deposits including the Adamantina Formation, this suggests that the physical connection between North and South America was not established until the end of the Cretaceous. Acknowledgments We thank Agustin G. Martinelli (Museo Argentino de Ciencias Naturales, Buenos Aires) for thorough and helpful comments that greatly improved this manuscript. For references, we thank Jeffrey A. Wilson (University of Michigan), P. Upchurch (University of Cambridge) and F. Novas (Museo Argentino de Ciencias Naturales). The authors also thank Alberto Garrido (Museo Carmen Funes, Cipoletti) and an anonymous reviewer for critically reading the manuscript and providing valuable suggestions. We specially thank Lílian Paglarelli Bergqvist, Leonardo S. Avilla and Erika Abranches (Laboratório de Macrofósseis, Departamento de Geologia, Universidade Federal do Rio de Janeiro) for allowing us free access to laboratories and specimens in their charge. Adelino Carvalho, Cláudia Regina A. Candeiro, Edeilson P. Silva, Edivane Cardoso, Flávio Oliveira, Jorge Augusto Albuquerque, Patricia Tavares (Uberlândia), and Sérgio Moraes (Prata) deserve many thanks for assistance during 2002–2003 field seasons. Cláudia Regina A. Candeiro (Uberlândia) and Éric Buffetaut (Research at Centre National de la Recherche Scientifique, Paris) made résumé observations and correction of the grammar. References Albuquerque, J.A.C., Oliveira, E.C., Marinho, T.S., Candeiro, C.R.A., 2003. Jazigos fossilíferos cretácicos do Triângulo Mineiro, indentificação e mapeamento. Boletim de Resumos do 18e Congresso Brasileiro de Paleontologia. Brasília-DF, Brazil (2003, pp. 322). Almeida, E.B., Avilla, L.S., Candeiro, C.R.A., 2003. Restos caudais associados a Titanosauridae do Cretáceo Superior da Formação Adamantina, Bacia Bauru, Município do Prata – MG. Boletim de Resumos do 18e Congresso Brasileiro de Paleontologia. Brasília-DF, Brazil (2003, pp. 36).
Almeida, E.B., Avilla, L.S., Candeiro, C.R.A. 2004, Restos associados a Titanosauridae do Cretáceo Superior da Formação Adamantina, Bacia Bauru, Município do Prata – MG. Revista Brasileira de Paleontologia 7 (2), 239– 244. Barcelos, J.H., 1984. Reconstrução paleogeográfica da sedimentação do Grupo Bauru baseada na sua redefinição estratigráfica parcial em território paulista e no estudo preliminar fora do estado de São Paulo. Unpublished Ph.D. thesis, Universidade Estadual Paulista, Rio Claro, Brasil. Bonaparte, J.F., 1986. History of the terrestrial Cretaceous vertebrales of Gondwana. IVo Congreso Argentino de Paleontología y Bioestratigrafía (Mendonza), Actas 4, 63–95. Bonaparte, J.F., 1996. Cretaceous tetrapods of Argentina. Münchner Geowissenchaftlichen Abhandlungen 30, 73–130. Bonaparte, J.F., Coria, R.A., 1993. Un Nuevo y gigantesco saurópodo titanosaurio de la Formación Río Limay (Albiano-Cenomaniano) de la Provincia del Neuquén, Argentina. Ameghiniana 30, 271–282. Bonaparte, J.F., Franchi, M.R., Powell, J.E., Sepúlveda, E.G., 1984. La Formación Los Alamitos (Campaniano-Maastrichtiano) del sudeste de Río Negro, con descripción de Kritosaurus australia n. sp. (Hadrosauridae). Significado paleogeográfico de los vertebrados. Revista de la Asociación Geológica Argentina 39, 284–299. Candeiro, C.R.A., 2002. Dentes de Theropoda da Formação Marília (Santoniano–Maastrichtiano), Bacia Bauru, Região de Peirópolis, Uberaba, Minas Gerais, Brazil. Unpublished Ms. thesis, Universidade Federal do Rio de Janeiro, Brasil. Candeiro, C.R.A., Abranches, C.T., Abrantes, E.A., Avilla, L.S., Martins, V. C., Moreira, A.L., Torres, S.R., Bergqvist, L.P., 2004. Dinosaur remains from Western São Paulo State, Brazil (Bauru Basin, Adamantina Formation, Upper Cretaceous). Journal of South American Earth Science 18, 1– 10. Candeiro, C.R.A., Marinho, T.S., Novais, G.T., Franco, A.C., Albuquerque, J. A.C., Oliveira, E.C., 2003. Previously unreported result from the Upper Cretaceous of the Paleontological Site of Prata, Minas Gerais State, Brazil. Boletim de Resumos do 3e Simpósio Brasileiro de Paleontologia de Vertebrados. Rio de Janeiro-RJ, Brazil (2003, pp. 20). Coria, R.A., Salgado, L., 1995. A new giant carnivorous dinosaur from the Cretaceous of Patagonia. Nature 377, 224–226. De Valais, S., Apesteguía, S., Sauthier, D.U., 2003. Nuevas evidencias de dinosaurios de la Formación Puerto Yeruá (Cretácico), Provincia de Entre Ríos, Argentina. Ameghiniana 40, 631–635. Dias-Brito, D.E.A., Musacchio, J.C., Castro, M.S.A., Maranhão, J.M., Suárez, J.M., Rodrigues, R., 2001. Grupo Bauru: uma unidade continental do Cretáceo do Brasil – concepções baseadas em dados micropaleontológicos, isotópicos e estratigráficos. Revue de Paléobiologie 2, 245–304. Fernandes, L.A., Coimbra, A.M., 1996. A Bacia Bauru (Cretáceo Superior, Brasil). Anais da Academia Brasileira de Ciências 68, 195–205. Goldberg, K., Azevedo, S.A.K., Garcia, A.J., 1995a. A ocorrência de fósseis de dinossauros no Município de Prata, MG. Boletim de Resumos do 14e Congresso Brasileiro de Paleontologia. Uberaba-MG, Brazil (1995, pp. 53). Goldberg, K., Garcia, A.J., Azevedo, S.A.K., 1995b. Geologia e paleoambiente dos sedimentos associados aos depósitos fossíliferos do Município de Prata, MG. Boletim de Resumos do 14e Congresso Brasileiro de Paleontologia. Uberaba-MG, Brazil (1995, pp. 54). Goldberg, K., Garcia, A.J.V., 2000. Palaeogeography of the Bauru Group, a dinosaur-bearing Cretaceous unit, northeastern Paraná Basin, Brazil. Cretaceous Research 21, 241–254. Henriques, D.R., Kellner, A.W.A., Azevedo, S.A.K., Santos, D.D., Craik, M. M.T., 2002. On a sauropod dinosaur (Titanosauridae) from the Adamantina Formation (Late Cretaceous). Journal of Vertebrate Paleontology, Abstracts 22, 64A. Von Huene, F., 1927. Contribución a la paleogeografía de Sud-América – II. Las relaciones paleogeograficas de Sud América durante el Cretáceo Superior. Academina Nacional de Ciencias de Córdoba 30, 256–294. Von Huene, F., 1939. Carta de F. von Huene ao Dr. Euzébio de Oliveira. Mineração e Metalurgia 4, 1–190.
C.R.A. Candeiro et al. / Geobios 39 (2006) 319–327 Lamanna, M.C., Martínez, R.D., Smith, J., 2002. A definitive abelisaurid theropod dinosaur from the early Late Cretaceous of Patagonia. Journal of Vertebrate Paleontology 22, 58–69. Larsson, H.C.E., 1996. Cranial morphology of the African theropod Carcharodontosaurus saharicus (Allosauroidea). Journal of Vertebrate Paleontology 16, 47a. Leanza, H.A., Apesteguía, S., Novas, F., de la Fuente, M., 2004. Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages. Cretaceous Research 25, 61–87. Marinho, T.S., 2003. As ocorrências fossilíferas do Cretáceo Superior nos Municípios do Prata e Monte Alegre de Minas, no Triângulo Mineiro. Unpublished Undergraduate Monograph, Universidade Federal de Uberlândia, Uberlândia, Brazil. Marinho, T.S., Oliveira, E.C., Albuquerque, J.A.C., Ribeiro, L.C.B., Candeiro, C.R.A., 2003. Dinosaurs from the Bauru Basin (Upper Cretaceous). Boletim de Resumos do 18e Congresso Brasileiro de Paleontologia. BrasíliaDF, Brazil (2003, pp. 322). McIntosh, J.S., 1990. Sauropoda. In: Weishampel, D.B., Dodson, P., Osmólka, H. (Eds.), The Dinosauria. University of California Press, Berkeley, pp. 345–401. Moraes, S.F., Oliveira, E.C., Albuquerque, J.A.C., Novais, G.T., Marinho, T. S., Candeiro, C.R.A., 2003. New discoveries of vertebrates fossils and the occurrence of a new fossil location in the Prata Site (Upper Cretaceous), Minas Gerais State, Brazil. Boletim de Resumos do 21e Semana Científica de estudos Biológicos, Universidade Federal de Uberlândia. Uberlândia– MG, Brazil (2003, pp. 36). Novas, F.E., 1997. South American dinosaurs. In: Currie, P.J., Padian, K. (Eds.), Encyclopedia of Dinosaurs. Academic Press, San Diego, pp. 678– 689. Novas, F.E., Cambiaso, A.V., Ambrosio, A., 2004. A new basal iguanodontian (Dinosauria, Ornithischia) from the Upper Cretaceous of Patagônia. Ameghiniana 41, 75–82. Powell, J.E., 1986. Revisión de los titanosáuridos de América del Sur. Unpublished Ph.D. thesis, Universidad Nacional de Tucumán, Argentina. Powell, J.E., 2003. Revision of South American Titanosaurid dinosaurs: Paleobiological, Paleobiogeographical and Phylogenetic aspects. Records of the Queen Victoria, Melbourne 111, 1–173.
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Price, L.I., 1961. Sobre os dinossáurios do Brasil. Academia Brasileira de Ciências, Anais 33, 3–4. Salgado, L., 2000. Evolución y Paleobiología de los Saurópodos Titanosauridae. Unpublished Ph.D. thesis, Universidad Nacional de La Plata, Argentina. Salgado, L., Coria, R.A., 1993. El gênero Aeolosaurus (Sauropoda, Titanosauridae) em la Formacion Allen (Campaniano-Maastrichtiano) de la Província de Rio Negro, Argentina. Ameghiniana 30, 119–128. Salgado, L., Coria, R., 1996. First evidence of an armoured ornithischian dinosaur in the late Cretaceous of North Patagonia, Argentina. Ameghiniana 33, 367–371. Sereno, P.C., Dutheil, D.B., Iarochene, M., Larsson, H.C.E., Lyon, G.H., Magwenw, P., Sidor, C.A., Varrichio, D.J., Wilson, J.A., 1996. Predatory dinosaurs from the Sahara and Late Cretaceous faunal differentiation. Science 272, 986–991. Silva, E.P., Brito, I.M., Santos, A.R., Candeiro, C.R.A., Ribeiro, L.C., 2001. Sítio Paleontológico do Prata, Triângulo Mineiro. Boletim de Resumos do 17e Congresso Brasileiro de Paleontologia Rio Branco–AC, Brazil, (2001, pp. 195). Soares, P.C., Landim, P.M.B., Fulfaro, V.J., Neto, A.F.S., 1980. Ensaio de caracterização estratigráfica do Cretáceo no Estado de São Paulo: Grupo Bauru. Revista Brasileira de Geociências 10, 177–185. Stromer, E., 1931. Wirbeltierreste der Baharíje-Stufe (untertes Cenoman). 10. Ein Skellett-Rest von Carcharodotnosaurus nov. gen. Abhandlungen der Bayerischen Akademie der Wissenschaften Mathematich-naturwissenschaftliche Abteilung Neue Folge 9, 1–23. Suguio, K., Barcelos, J.H., 1983. Paleoclimatic evidence from the Bauru Group, Cretaceous of Paraná Basin, Brazil. Revista Brasileira de Geociências 13, 232–236. Vickers Rich, P., Rich, T.H., Lanus, D.R., Rich, L.S., Vacca, R., 1999. “Big tooth” from the Early Cretaceous of Chubut province, Patagonia: a possible Carcharodontosaurid. National Science Museum Monographs 15, 85– 88. Wilson, J.A., Upchurch, P., 2003. A revision of Titanosaurus Ludekker (Dinosauria-Sauropoda), the first dinosaur genus with a “Gondwanan” distribution. Journal of Systematic Paleontology 1, 125–160.
Original article
Vertebrate fossils from the Adamantina Formation (Late Cretaceous), Prata paleontological district, Minas Gerais State, Brazil Vertébrés fossiles du Crétacé supérieur de la Formation Adamantina, district paléontologique de Prata, État de Minas Gerais, Brésil Vertebrados fósseis da Formação Adamantina (Neocretáceo) do Distrito Paleontológico do Prata, Estado de Minas Gerais, Brasil Carlos Roberto A. Candeiro a,b,*, Adriano R. Santos a, Thomas H. Rich c,d, Thiago S. Marinho a,b, Emerson C. Oliveira a a
Museu de minerais e rochas, Universidade federal de uberlândia (UFU), Avenida João Naves de Ávila 2160, 38408-100 Uberlândia, MG, Brazil b Laboratório de macrofósseis, departamento de geologia, Universidade federal do Rio de Janeiro (UFRJ), avenida Brigadeiro Trompowski, s/n, Ilha do Fundão, 21949-900 Rio de Janeiro, RJ, Brazil c Museum of Victoria, PO Box 666E, Melbourne, Victoria, Australia d School of geosciences, PO Box 28E, monash University, Victoria 3800, Australia Received 11 May 2004; accepted 21 October 2004 Available online 22 May 2006
Abstract In this contribution is given a preliminary up-to-date annotated list of all fossil vertebrates from the Turonian–Santonian Adamantina Formation, Bauru Group where it occurs in the Prata paleontological district which is located 45 km to the west of Prata in Minas Gerais State, Brazil. The Adamantina Formation is a reddish sandstone in the Triângulo Mineiro region. These fluviolacustrine sediments were deposited in a semiarid environment. Three fossil vertebrate sites occur in the Prata paleontological district. The diversity of vertebrates in the Adamantina Formation is modest, and its components comprise a mixture of typical austral Gondwana taxa (such as abelisaurids, Aeolosaurus) and boreal Gondwana taxa (such as Carcharodontosauridae). The absence of Laurasian taxa in the upper part of the Bauru Group is noteworthy. Excepting some turtles, crocodylians, and one titanosaurid, most of the specimens discovered in this Group are based on fragmentary and isolated remains, which make it difficult to correctly identify the fossils. For this reason, many of the taxa have only been identified in a preliminary manner. Despite this drawback, the dinosaurs are typical Gondwana forms with no evidence of Laurasian affinities. This is concordant with the idea that the Laurasian dinosaurs entered South America at the end of the Late Cretaceous; i.e. after the Turonian–Santonian, the age of the Adamantina Formation. © 2006 Elsevier SAS. All rights reserved. Résumé La liste des vertébrés fossiles est mise à jour dans la Formation Adamantina datée du Turonien-Santonien affleurant dans le district paléontologique de Prata à 45 km à l’est de Prata (Minas Gerais, Brésil). La Formation Adamantina est composée de grès rougeâtres dans la région du Triangle Minier. Les sédiments fluviolacustres se sont déposés dans un environnement semi-aride. Trois sites à vertébrés fossiles sont connus dans le district paléontologique de Prata. La diversité des vertébrés de la Formation Adamantina est réduite et comprend un mélange de taxons typiques du Gondwana austral (comme des Abelisauridés, Aeolosaurus) et des taxons du Gondwana boréal (comme des Carcharodontosauridae).
* Corresponding
author. E-mail address: [email protected] (C.R.A. Candeiro).
0016-6995/$ - see front matter © 2006 Elsevier SAS. All rights reserved. doi:10.1016/j.geobios.2005.10.003
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L’absence de taxons laurasiatiques dans la partie supérieure du Groupe Bauru est remarquable. Excepté quelques tortues, des crocodiliens et un titanosauridé, la plupart des spécimens découverts dans ce Groupe Bauru sont représentés par des restes fragmentaires et isolés. Pour cette raison, seules des identifications préliminaires sont proposées. Toutefois, les dinosaures sont typiques du Gondwana sans évidence d’affinité Laurasienne. Ceci est en accord avec l’hypothèse que les dinosaures laurasiens ne seraient arrivés en Amérique du Sud qu’à la fin de Crétacé supérieur, c’est-à-dire après le Turonien-Santonien, âge de la Formation Adamantina. © 2006 Elsevier SAS. All rights reserved. Resumo Na presente contribuição é apresentada uma listagem preliminar de todos os fósseis de vertebrados do Distrito Paleontológico do Prata (Formação Adamantina, Turoniano-Santoniano, Grupo Bauru). As rochas da Formação Adamantina são compostas por arenitos avermelhados que afloram na região do Triângulo Mineiro. Esses sedimetnos de origem fluvio-lacustre foram depositados em um ambiente semi-árido. São conhecidos três sítios de vertebrados fósseis que ocorrem no Distrito Paleontológico do Prata. A diversidade de vertebrados na Formação Adamantina é modesta sendo representados por uma mistura típica de taxa austrais do Gondwana (abelisaurídeos e Aeolosaurus) e boreais (carcarodotontosaurídeos). A ausência de taxa laurasianos na parte superior do Grupo Bauru é notável. Exceto pela presença de tartarugas, crocodilianos e um titanossaurídeo a maioria dos espécimes descobertos nessa unidade geológica é baseada em restos fragmentários e isolados os quais são de difícil identificação. Por essa razão, a maioria desses taxa têm sido somente identificados de forma preliminar. Considerando essa desvantagem, se pode afirmar que os dinossauros do Prata são tipicamente de formas gondwânicas com nenhuma evidência de formas laurasianas. Isso é concordante com a idéia de que os dinossauros laurasianos entraram na América do Sul somente no final do Neocretáceo, ex. depois do Turoniano-Santoniano, que é a idade da Formação Adamantina. © 2006 Elsevier SAS. All rights reserved. Keywords: Late Cretaceous; Brazil; Crocodiles; Dinosaurs; Turtles Mots clés : Crétacé supérieur ; Brésil ; Crocodiliens ; Dinosaures ; Tortues Palabras-chaves: Neocretáceo; Brasil; Crocodilos; Dinossauros; Tartarugas
1. Introduction Since the beginning of the last century, numerous specimens of fossil vertebrates have been collected from continental Cretaceous rocks of the Adamantina Formation, Bauru Group, in the Bauru Basin, Triângulo Mineiro region, Minas Gerais State. In the same area of Minas Gerais State, the Marília Formation (Ponte Alta and Serra da Galga Members) also has yielded fossil vertebrates. Both formations have produced faunas consisting primarily of fishes, turtles, crocodylians, and dinosaurs. All of these fossils occur in sandstones deposited in braided river channels. A large quantity of fossil bones has been found in the continental Cretaceous rocks exposed in the Prata paleontological district of the Triângulo Mineiro region of Minas Gerais State, Brazil (Fig. 1; Goldberg et al., 1995a, 1995b; Silva et al., 2001; Marinho, 2003; Candeiro et al., 2003; Marinho et al., 2003). For this reason, the Prata paleontological district, located 45 km west of the town of Prata, is known as one of the most important fossil locations, as it contains abundant remains of sauropod and theropod dinosaurs as well crocodylians and turtles. Many authors (Soares et al., 1980; Suguio and Barcelos, 1983; Barcelos, 1984; Candeiro, 2002) assign the sediments of Prata paleontological district to the Adamantina Formation (Bauru Group), which was dated as Turonian–Santonian in age (Dias-Brito et al., 2001). This unit is exposed at the Serra da Boa Vista Hill, in the vicinity of Prata. Some of the richest Cretaceous fossil vertebrate localities in Central Brazil occur in the Adamantina Formation. Many of the Adamantina Formation sites in the Prata paleontological
district have been known since the 1920s (Price, 1961). Owing to a lack of reliable lithological and paleontological data, the geological ages of these sites are not well established. The Adamantina Formation was formally proposed by Soares et al. (1980). The unit, 2–20 m thick, consists of rose to brown fine grained, cross-bedded sandstone. The type section of this formation was in the town of Adamantina, São Paulo State. In Triângulo Mineiro, the Adamantina Formation is the basal lithostratigrafic unit of the Bauru Group and is widely exposed in the area. In the Prata paleontological district, Triângulo Mineiro (Fig. 1), three fossil vertebrate sites occur in the Adamantina Formation. These three fossil sites represent the best record of Late Cretaceous vertebrates in the Minas Gerais State (Brazil). This makes those sites some of the most important when discussing the fossil record of Late Cretaceous in Minas Gerais State. The vertebrates reported here are from the Adamantina Formation near Prata, and belong to the following groups: abelisaurs, carcharodontosaurs, Aeolosaurus, and titanosaur dinosaurs, turtles, and crocodylians. More is known about the dinosaurs than any other group from the Prata paleontological district. The paleontologist Llewellyn Ivor Price first reported to the Departamento Nacional de Produção Mineral fragmentary dinosaur bones in 1940. The fossils were transferred to Rio de Janeiro (Price, 1961). Since then, there have been numerous fossil collecting trips to the Prata paleontological district that have yielded new dinosaurs and other vertebrate fossils (Silva et al., 2001). However, detailed stratigraphic studies based on dinosaur remains were not attempted.
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Fig. 1. Location of the Prata paleontological district, and geographic distribution of the Cretaceous fossiliferous location.
2. Geological setting The Adamantina Formation was defined by Soares et al. (1980) and is known in the following states of Southeast Brazil: Goiás, Mato Grosso do Sul, Minas Gerais and São Paulo. These authors regarded it as part of the Bauru Group, which occurs in the Paraná Basin. Based on variation in the regional lithology, Barcelos (1984) divided the Adamantina Formation into two units: the Araçatuba and São José do Rio Preto Members. The Prata paleontological district is currently regarded as formed by rocks of the Bauru Group (Late Cretaceous) (Fig. 2). In the Triângulo Mineiro region, the Adamantina,
Marília and Uberaba formations sensu Fernandes and Coimbra (1996) form part of Bauru Group. These rocks overlay the basalt layers of the Serra Geral Formation. Goldberg and Garcia (2000) described the Adamantina Formation (Fig. 3) in the Prata paleontological district as very fine to fine grained, well-sorted, cross-bedded red sandstones. Furthermore, these authors recognized intraformational conglomerates and subordinate red shales, which are massive or laminar. The top of this unit is characterized by the interbedding of (1) conglomerates, (2) fine- to medium-grained crossbedded sandstones and (3) abundant nodular and horizontal carbonate concretions, which coarsen and thicken upward.
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Fig. 2. Geological map of the Bauru Group (Upper Cretaceous) in the Triângulo Mineiro region, Minas Gerais State, Brazil (modified de Fernandes and Coimbra, 1996).
Von Huene (1927, 1939) regarded the Adamantina Fm as Senomanian based on a correlation made between the turtle Najadochelys and the sauropod “Titanosaurs australis” with similar taxa recorded in northern Patagonia, Argentina. Based on ostracods and caryophytes, Dias-Brito et al. (2001) considers the age of this Formation to be Turonian–Santonian (92–83 my). 3. Vertebrate paleontology
Fig. 3. Bauru Group lithostratigraphic chart in Prata area (modified from Suguio and Barcelos, 1983).
The Late Cretaceous sequence of the Prata paleontological district contains fossil remains of crocodylians, dinosaurs and turtles (Table 1; Silva et al., 2001; Marinho, 2003; Albuquerque et al., 2003; Marinho et al., 2003; Moraes et al., 2003). The fossil occurrences are in hilly areas located west of Prata (Fig. 1). Because of the fragmentary nature of the fossils collected thus far, they have not been identified to a refined taxonomic level except the genus Aeolosaurus.
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Table 1 Vertebrate fauna of the Adamantina Formation from Prata paleontological district. See footnotes for source references included. 1 Goldberg et al. (1995a, 1995b), 2 Silva et al. (2001), 3 Marinho (2003), 4 Albuquerque et al. (2003), 5 Candeiro et al. (2003), 6 Marinho et al. (2003), 7 Moraes et al. (2003), 8 Henriques et al. (2002), 9 Almeida et al., 2003 (in press) Taxa
Vertebrata Vertebrata indet 1–7 Reptilia Chelonia indet. 2 Crocodylomorpha indet. 2 Dinosauria Sauropoda Titanosauria 2–8 Aeolosaurus 9 Theropoda Theropoda indet. 3-7 Abelisauridae 3, 7 Carcharodontosauridae 3
Location 1 Boa vista hill GPS. 19°27′26.0″S and 49°14′42.6″W.
Location 2 Outskirt GPS. 19°26′21.0″S and 49°15′41.3″W.
Location 2 “Idelmo Bramh farm” GPS. 19°26′31.8″S and 49°14′27.8″W.
x
x
x
x x
x x x x x
Fig. 4. Dinosaur remains from Prata paleontological district. A, labial view, B, lingual view Abelisauridae tooth (MMR/UFU-PV 0006); C, labial view, D, lingual view, Carcharodontosauridae tooth (MMR/UFU-PV 005); E, labial view, F, lingual view, Theropoda tooth (MMR/UFU-PV 007). Bar scale represent 30 mm. G, lateral view, Titanosauria caudal vertebrae (MMR/UFU-PV 0001); H, I, lateral view, Titanosauria ribs. Bar scale A, B, C, D, E, F bar scale = 30 mm; G = 10 mm; H, I = 50 mm.
3.1. Remarks about the dinosaurs of the Prata district Dinosaurs are the best-known and most diverse taxa from Prata Site. This material is housed mainly at MMR and UFRJ-DG and briefly commented here.
Abbreviations: MACN, Museo Argentino de Ciencias Naturales, Buenos Aires, Argentina; MUCPV-CH, Museo de la Universidad Nacional de Comahue, El Chocon collection; MMR/UFU-PV, Museu de Minerais e Rochas, Universidade Federal de Uberlândia, Uberlândia, Minas Gerais, Brazil;
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RTMP, Royal Tyrrell Museum of Palaeontology, Drumheller, Canada; UFRJ-DG-R, Departamento de Geologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil, fossil reptilian collection. 3.1.1. Systematic paleontology Suborder THEROPODA Marsh, 1881 ABELISAURIA Novas, 1992 Family ABELISAURIDAE Bonaparte and Novas, 1985 Material: (MMR/UFU-PV 0006) (Fig. 4A, B). Locality: 2. Remarks: the Abelisauridae are represented by a single tooth (MMR/UFU-PV 0006) from locality 2 on the western side of the Prata paleontological district. This tooth was described recently by Marinho (2003). It lacked a root but the preservation of the crown is good. It is small (32 mm), with serrated anterior and posterior carinae, the denticles on the proximal part of the anterior carina are smaller than those on the distal part, and denticles on the middle are largest. All the denticles on the distal part are pointed toward the crown apex. The denticles on the proximal and middle part of the anterior carina are perpendicular to the crown apex. The denticles on both carinae are higher than wide. The denticles of the proximal and distal parts of the posterior carinae are the same size; those in the middle are larger. The cross-section of the tooth has the anterior face compressed and posterior face convex (MMR/UFU-PV 0006) has the labial and lingual faces more convex in cross-section nears the anterior edge and flatter posteriorly; the lingual face is also slightly concave proximodistally. The characters exhibited by the low crown tooth from MMR/UFU-PV 0006 clearly indicate that it represents an abelisaurid. Bonaparte (1996), Lamanna et al. (2002), Wilson and Upchurch (2003), and Candeiro et al. (2004) noted the presence of a low crown in the Abelisauridae (e.g. Aucasaurus garridoi, Carnotaurus sastrei, Rajasarus narmadensis) teeth and regarded it as a diagnostic character of the family. Candeiro et al. (2004) pointed that abelisaurid teeth are characterized by labial and lingual faces more convex in cross-section near the anterior edge and flatter posteriorly; the lingual face is also slightly concave proximodistally. The cross-section of the specimen (MMR/UFU-PV 0006) is exactly as in the Abelisauridae. Family CARCHARODONTOSAURIDAE Stromer, 1931 Material: (MMR/UFU-PV 005) (Fig. 4C, D). Tooth. Locality: 2. Remarks: Marinho (2003) recently described MMR/UFUPV 005, which has a labial side of the tooth that is convex on its more anterior portion and posteriorly flattened. As on the labial side, the anterior part of the lingual side is slightly convex, becoming posteriorly flattened. The posterior region of the lingual side bears acute wrinkles on the enamel, which are very well developed, on the proximal and medial region, but these vanish toward the crown tip. Each wrinkle is obliquely oriented with respect to the tooth margin, but bends along its length
away from tooth margin until its orientation is transverse with respect to the tooth’s long axis. The wrinkle then continues across the tooth surface as a horizontal band. The posterior denticles on the proximal and distal ends are equal, while the middle denticles are larger. The anterior denticles are smaller than the posterior ones. All the denticles of both carinae are perpendicular to the crown apex, and are rather higher than wide. The cross-section is chestnut-shaped. The outline of the tooth in lateral view is in the form of a rough isosceles triangle. The presence of wrinkles on a theropod teeth tooth crown has been considered as a diagnostic feature for Carcharodontosauridae (Carcharodontosaurus saharicus and Giganotosaurus carolinii) by many authors (Larsson, 1996; Sereno et al., 1996; Vickers Rich et al., 1999; Candeiro et al., 2004). In Giganotosaurus carolinii different forms of wrinkles occur (Candeiro pers. obsers.) which can be strong or subdued. These wrinkles may or may not be close to the crown border (e.g. Carcharodontosaurus and Giganotosaurus). The wrinkles on the crown of MMR/UFU-PV 005 are strong and similar to the wrinkles found in carcharodontosaurids. This specimen is mediolaterally compressed and thus quite similar to Carcharodontosaurus saharicus (Stromer, 1931) and the Giganotosaurus (MUCPV-CH-1 and casts of MACN S/N and RTMP 94.43.1, 94.43.2, 94.43.3, 94.43.4). The presence of carcharodontosaurids in the PPD is especially noteworthy as it represents the youngest record of this clade found to date (Turonian–Santonian). Previously, the youngest known records of carcharodontosaurids are from Cenomanian beds in Africa, Argentina and Maranhão State in Brazil. Carcharodontosaurid teeth from the MMR/UFU-PV 005 of Late Cretaceous age contrast with the osteological record of Carcharodontosauridae, which is mainly restricted to older parts of the Cretaceous (e.g. Albian–Turonian) of Africa and South America. Order THEROPODA indet. Material: (MMR/UFU-PV 0007) (Fig. 4E, F). Tooth. Locality: 2. Remarks: no family assignment could be made for MMR/ UFU-PV 0007, but there is no doubt that this specimen belongs to a theropod dinosaur as it is strongly labio-lingually compressed and shows denticles with great variation in size and shape throughout the carina. Their cross-sections are different from any of the known Gondwanan Theropoda, but it is important to note that the teeth of some Gondwanan dinosaurs are still unknown (Novas, 1997). TITANOSAURIA Bonaparte and Coria, 1993 Genus Aeolosaurus Powell, 1986 Aeolosaurus indet. Material: (UFRJ-DG 270-R). Caudal vertebra. Locality: 2. Remarks: the sauropods are the most common and abundant fossil vertebrate remains found in the region (Fig. 4G–I). Numerous postcranial bones represent them. Almeida et al. (2003, 2004) (UFRJ-DG 270-R caudal vertebra) (Fig. 5A–C)
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tion of this caudal vertebrate is a synapomorphic feature that allies it with the “Titanosauridae” (Bonaparte and Coria, 1993; Wilson and Upchurch, 2003). The heart-shaped posterior articular facet and wide prezygapophyses allow us to relate this vertebra to the taxa Gondwanatitan/Aeolosaurus. Recently, a titanosaurid (MN 5013-V) was recognized at the same locality (the Boa Vista Hill) (Table 1). However, Almeida et al. (2004) pointed out that the specimen lacked features of the Gondwanatitan/Aeolosaurus complex. Henriques et al. (2002) suggested that this fossil was a new taxon closely related to these genera. TITANOSAURIA indet Material: (MMR-UFU-PV 001). Caudal vertebrae. Locality: 2. Remarks: there are several fragments of disarticulated bones found in Adamantina Formation sediments in the Prata paleontological district that have not previously been attributed to the Titanosauridae (sensu Powell, 1986, 2003; McIntosh, 1990). These specimens are caudal vertebrae (MMR-UFU-PV 001; Fig. 4G) that are strongly procoelous, having “ball socket” posterior articular faces. According Powell (1986, 2003) and McIntosh (1990) among Titanosauria, titanosaurids developed anterior caudals with a deeply excavated anterior face much like a “socket” and a posterior articulation like a prominent “ball”.
Fig. 5. Aeolosaurus caudal vertebra UFRJ-DG 270-R. Lateral view (A), posterior (B) and anterior (C). Abbreviations: CN, neural canal; PRZ, postzigapophysis; PT, transverse process; PZ, postzygapophysy; SN, neural spine. Scale bar 50 mm.
and Henriques et al. (2002) reported the presence of titanosaurid sauropods. Almeida et al. (2003, 2004) recognized the titanosaurid genus Aeolosaurus, which was first described from the Late Cretaceous of Patagonia (Argentina) (Powell, 1986, 2003; Salgado and Coria, 1993; Salgado, 2000). Although this vertebra is almost complete, it did suffer some damage. This damage made it possible to observe the internal spongy composition (Fig. 5B) of the bone. The vertebral centrum is deep and relatively low, procoelous, and bears a heart-shaped anterior articular facet (Fig. 5C). The transverse process is well developed and positioned at the centro-neural suture. The base of the neural arch is positioned anteriorly in relation to the vertebral centrum. The neural canal is oval—the lateral diameter is the longer one. The neural spine is large and posteriorly oriented, showing a well-developed prespinal laminae (PRSL) (Fig. 5A). The spinoprezygapophyseal laminae are also well developed and both are joined to the base of the PRSL. The postzygapophysis is well marked. The haemal arch is straight and laterally compressed. Although its proximal region is fragmented, its Y-shaped nature is readily seen. The open haemal canal indicates that this caudal vertebra belongs to the Camarasauromorpha. Within that group, the procoelous condi-
3.1.2. Adamantina Formation fossil localities in the Prata paleontogical district Price studied the first fossil site in the Prata paleontological district in the 1950’s. However, it was only in 2002 that fossil localities in the Adamantina Formation were discovered in that area by researchers from the Universidade Federal de Uberlândia (Museu de Minerais e Rochas). Three fossil vertebrate sites in the Adamantina Formation are mentioned in the literature (e.g. Albuquerque et al., 2003). The best-known vertebrate fossils of Adamantina Formation occur in the Prata paleontological district and are listed in Table 1. 4. Concluding remarks The fossils from the Prata paleontological district are all vertebrates mainly collected at the Boa Vista Hill fossil site, Locality 2. The best-known taxa from the Adamantina Formation are referred to the Abelisauridae, Carcharodontosauridae and Titanosauria (Aeolosaurus and Titanosauria indet.). Although the vertebrate fossil record of Prata District is currently poorly known, with few well-preserved specimens, many fragmentary remains have been found. Fossil localities are centered in the western parts of Prata municipality, and resemble the fauna from southern South America (Patagonia). The dinosaurs of the Prata District comprise two families of Gondwanan theropods (Abelisauridae and Carchadorodontosauridae), one genus of titanosaurs (Aeolosaurus). Single crocodilian and turtle records are reported in the literature from the Prata District. Their presence supports the earlier conclu-
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sions of Von Huene (1927, 1939) that correlated the fauna of Adamantina Formation with those found in the Late Cretaceous of Argentina or even those of Africa, India and Madagascar. Although only a few of the named Prata taxa have been fully reported, a picture is emerging which suggests a Gondwanan origin for the assemblage (Bonaparte, 1986). Carcharodontosaurs are common in the early Late Cretaceous in South America (Coria and Salgado, 1995; Leanza et al., 2004), but in the Prata District of Minas Gerais State a record of this group indicates that it possibly survived into the Late Cretaceous. Titanosaurs and abelisaurs dominate the Late Cretaceous in the Gondwana landmasses. They are found also in Late Cretaceous of the Prata District. Aeolosaurus is found not only in the Prata paleontological district but also in the Late Cretaceous of Argentina. Typical Laurasian taxa such as ornithischians have been widely documented in several Late Cretaceous units of Southern South America (e.g. Bonaparte et al., 1984; Salgado and Coria, 1996; De Valais et al., 2003; Novas et al., 2004). Because they are absent from earlier Turonian–Santonian deposits including the Adamantina Formation, this suggests that the physical connection between North and South America was not established until the end of the Cretaceous. Acknowledgments We thank Agustin G. Martinelli (Museo Argentino de Ciencias Naturales, Buenos Aires) for thorough and helpful comments that greatly improved this manuscript. For references, we thank Jeffrey A. Wilson (University of Michigan), P. Upchurch (University of Cambridge) and F. Novas (Museo Argentino de Ciencias Naturales). The authors also thank Alberto Garrido (Museo Carmen Funes, Cipoletti) and an anonymous reviewer for critically reading the manuscript and providing valuable suggestions. We specially thank Lílian Paglarelli Bergqvist, Leonardo S. Avilla and Erika Abranches (Laboratório de Macrofósseis, Departamento de Geologia, Universidade Federal do Rio de Janeiro) for allowing us free access to laboratories and specimens in their charge. Adelino Carvalho, Cláudia Regina A. Candeiro, Edeilson P. Silva, Edivane Cardoso, Flávio Oliveira, Jorge Augusto Albuquerque, Patricia Tavares (Uberlândia), and Sérgio Moraes (Prata) deserve many thanks for assistance during 2002–2003 field seasons. Cláudia Regina A. Candeiro (Uberlândia) and Éric Buffetaut (Research at Centre National de la Recherche Scientifique, Paris) made résumé observations and correction of the grammar. References Albuquerque, J.A.C., Oliveira, E.C., Marinho, T.S., Candeiro, C.R.A., 2003. Jazigos fossilíferos cretácicos do Triângulo Mineiro, indentificação e mapeamento. Boletim de Resumos do 18e Congresso Brasileiro de Paleontologia. Brasília-DF, Brazil (2003, pp. 322). Almeida, E.B., Avilla, L.S., Candeiro, C.R.A., 2003. Restos caudais associados a Titanosauridae do Cretáceo Superior da Formação Adamantina, Bacia Bauru, Município do Prata – MG. Boletim de Resumos do 18e Congresso Brasileiro de Paleontologia. Brasília-DF, Brazil (2003, pp. 36).
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