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Amazonsaurus maranhensis gen. et sp. nov. (Sauropoda, Diplodocoidea) from the Lower Cretaceous (Aptian-Albian) of Brazil
Abstract
A new genus and species of an Aptian–Albian sauropod from the Itapecuru Formation, northern Brazil, Amazonsaurus maranhensis, is described. It is known from an incomplete, but diagnostic postcranial skeleton. The new taxon possesses several autapomorphies, such as the anterior caudal vertebrae with lateral laminae formed by the coalescence of the spinoprezygapophyseal and postzygodiapophyseal laminae and, to a lesser extent, of the postzygodiapophyseal laminae. It exhibits many synapomorphies
supporting its inclusion in the Diplodocoidea. These include high caudal neural arches and anterior caudal neural arches with spinoprezygapophyseal laminae on the lateral aspect of the neural spine. This record is consistent with previous hypotheses on the existence of a community of Afro-South American dinosaurs.
... A record of a rebbachisaurid from Asia has recently been reported (Averianov and Sues 2021), but its taxonomic assignment has been questioned (Lerzo et al. 2021), and the enigmatic North American taxon Maraapunisaurus (formerly Amphicoelias) fragillimus has been referred to Rebbachisauridae, albeit on the basis of missing material (Carpenter 2018). Despite the broad paleogeographic distri-bution of the group, the greatest diversity and abundance of rebbachisaurid sauropods are known from the Cretaceous of South America, especially in Neuquén Basin from Argentina (Calvo and Salgado 1995;Bonaparte 1996Bonaparte , 1997Dalla Vecchia 1998;Sereno et al. 1999;Carvalho et al. 2003; Gallina and Apesteguía 2005;Salgado et al. 2006;Apesteguía 2007;Taylor and Naish 2007;Carballido et al. 2010;Torcida et al. 2011;Salgado et al. 2012;Fanti 2013Fanti , 2015Ibiricu et al. 2013Ibiricu et al. , 2015Canudo et al. 2018;Lindoso et al. 2019;Bellardini et al. 2022). ...
... In lateral view, the neural spine is directed backwards as occurs in most anterior caudal vertebrae of rebbachisaurids (Pereda Suberbiola et al. 2003;Gallina and Apesteguía 2005;Torcida et al. 2011;Ibiricu et al. 2013Ibiricu et al. , 2015. Furthermore, the neural spine of MDPA-Pv 007 is straight rather than curved, as in anterior caudal vertebra of specimens belonging to Amazonsaurus maranhensis (Carvalho et al. 2003), Itapeuasaurus cajap Internal anatomy.-The ventral region of the centrum is thick and solid (Fig. 3). ...
... In anterior view, the apex of the neural spine is convex, as in most of Rebbachisauridae (e.g., Amazonsaurus maranhensis, Demandasaurus darwini, Nigersaurus taqueti, Reb bachi saurus garasbae, Rebbachisauridae indet. MIGW 5384;Sereno et al. 1999;Carvalho et al. 2003;Mannion et al. 2011;Torcida et al. 2011;Wilson and Allain 2015), differing from Zapalasaurus bonapartei and Rebbachisauridae indet. MAU-PV-EO-666 whose the dorsal surface of the spine is slightly transversely concave. ...
... The neural spine of the second anterior caudal vertebra of Agustinia shows an elliptical surface in dorsal view, wider than long due to the wellprominent laterodorsal margins of the ll ( Figure 8B). In lateral view ( Figure 8A), the dorsal surface is slightly convex, as occurs in some rebbachisaurids, such as Amazonsaurus, Demandasaurus, Limaysaurus, and Zapalasaurus (Calvo and Salgado 1995;Carvalho et al. 2003;Salgado et al. 2006;Torcida et al. 2011). On the other hand, the prsl is convex ventrally and almost straight more dorsally, as in Demandasaurus, and is slightly more prominent than the posl in lateral view (Torcida et al. 2011). ...
... This specimen preserves most of the dorsal portion of the neural spine, including the prsl, posl, and ll ( Figure 8). In dorsal view, the apical surface of the spine is rhomboidal ( Figure 8B), slightly longer than wide, whereas it is slightly convex and posterodorsally inclined in lateral view ( Figure 8A), as in Amazonsaurus (Carvalho et al. 2003). The ll is on the posterior half of the neural spine, showing a sinusoidal shape in lateral view, with the ventral portion posteriorly directed and a gently anteriorly bevelling close to the dorsal surface of the spine, as seen in the caudal vertebra of Cathartesaura (Gallina and Apesteguia 2005). ...
... In some diplodocoids and several rebbachisaurids (e.g. Marsh 1877; Calvo and Salgado 1995;Carvalho et al. 2003;Gallina and Apesteguía 2005;Fanti et al. 2013;Ibiricu et al. 2013;Wilson and Allain 2015) the ll is a laminar complex resulting from the merging of different neural laminae ( Figure 4I-R). In Amazonsaurus, Limaysaurus, and Tataouinea the ll is composed for the sprl+spol, whereas in Apatosaurus it is the lat. ...
The Lohan Cura Formation (Albian) at the Cerro de los Leones locality (Neuquén Province, Patagonia, Argentina) yielded several fossil materials, especially sauropod specimens. Among these, Agustinia ligabuei includes postcranial elements of a single individual, with widely debated taxonomy and phylogeny. Here, we provide an extended osteological description and illustrations of the axial and appendicular elements of Agustinia, as well as a revised diagnosis. Moreover, the phylogenetic analysis including a new combination of morphological features recognises Agustinia as a basal Rebbachisauridae, closely related with other South American rebbachisaurids. Our results suggest a more diversified sauropod fauna in the Neuquén Basin, where different members of both neosauropod lineages (i.e. Macronaria and Diplodocoidea) survived in the same region during the Albian age. The reassessment of Agustinia as a basal rebbachisaurid improves our knowledge about the early stages of evolutionary history of Rebbachisauridae, adding new information on the morphological and taxonomic diversification of the clade during the Early Cretaceous of southwestern Gondwana.
... The neural spine is tall, almost two times than the posterior centrum height and petal-shaped in anterior view, as in Nigersaurus, Demandasaurus (Fig. 5.9), Limaysaurus, and MIWG 5384 (Calvo & Salgado, 1995;Sereno et al., 1999;Mannion et al., 2011;Torcida et al., 2011) (Fig. 5.8). In MAU-EO-PV-666, the neural spine is dorsally directed in lateral view ( Fig. 5.3, 5) & Salgado, 1995;Carvalho et al., 2003;Gallina & Apesteguía, 2005;Mannion et al., 2011;Torcida et al., 2011;Ibiricu et al., 2012;Fanti et al., 2013Fanti et al., , 2015Lindoso et al., 2019). The ll, the prsr, and the posr are prominent with a tetraradiate arrangement in cross-section, as in most Rebbachisauridae (e.g., Calvo & Salgado, 1995;Pereda Suberbiola, 2003;Fanti et al., 2013Fanti et al., , 2015Wilson & Allain, 2015). ...
... However, the proximal portion of the neural spine is incomplete, and the origin of the lat. spol is unknown; thus, we prefer to consider the (Carvalho et al., 2003;Mannion et al., 2011;Fanti et al., 2013Fanti et al., , 2015Wilson & Allain, 2015). In anterior view, the dorsal surface of the neural spine is transversely concave ( Fig. 5.1), as in Zapalasaurus (Salgado et al., 2006), and not convex as in most of Rebbachisauridae (Fig. 5.6-9) (e.g., ...
... MIGW 5384; Sereno et al., 1999;Carvalho et al., 2003;Mannion et al., 2011;Torcida et al., 2011;Wilson & Allain, 2015). In posterior view, the spol are poorly preserved and limited to the basal portion of the spine, whereas the posr is prominent, rough, and slightly wider proximally than distally ( Fig. 5.2). ...
In the central Neuquén Basin, the Huincul Formation comprises thick successions of Upper Cretaceous fluvial deposits widely exposed at the south and north-west of Huincul High. The vertebrate fossil record from the Huincul Formation is very abundant, especially
considering the saurischian dinosaurs, including several theropod (Mapusaurus, Taurovenator, Aoniraptor, Skorpiovenator, Ilokelesia, Gualicho, Overoraptor, Tralkasaurus, and Huinculsaurus) and sauropod specimens (Choconsaurus, Argentinosaurus, Cathartesaura, Limaysaurus, and the indeterminate rebbachisaurid MMCH-Pv-49). In this contribution, we describe new rebbachisaurid sauropod findings from the El Orejano locality (Neuquén Province, Argentina), where coarse sandstones outcrop referred to the lower section of the Huincul Formation. The new material includes three axial elements that we refer to Rebbachisauridae: a partial dorsal neural arch (MAU-Pv-EO-633), an incomplete dorsal vertebra (MAU-Pv-EO-634), and an almost complete caudal vertebra (MAU-Pv-EO-666). These new findings share different features with other members of that family, although show some morphological differences with other rebbachisaurid taxa, which suggest a more diversified fauna in the central Neuquén Basin than previously known, at least during the Cenomanian/Turonian interval. This record from the new fossiliferous locality of El Orejano allows us to improve our knowledge about the morphological diversity of the Rebbachisauridae during the early Late Cretaceous. Furthermore, it represents one of the most modern records of the family, adding new information on the last stages of the evolutionary history of rebbachisaurids.
... The third rebbachisaurid described is the rather fragmentary Amazonsaurus maranhensis (Carvalho et al. 2003), the first member of the clade undoubtedly from the Lower Cretaceous, and the first one recorded in Brazil, although it was not originally considered as a rebbachisaurid but as a basal diplodocoid. ...
... Amazonsaurus Carvalho, Avilla and Salgado 2003 Amazonsaurus maranhensis Carvalho, Avilla and Salgado 2003 Holotype Two dorsal neural spines (MN 4558-V; UFRJ-DG 58-R/9); two dorsal centra (MN 4559-V; MN s/n(-V); neural spine of anterior caudal vertebra (UFRJ-DG 58-R/7) (Fig. 2); one mid-caudal vertebra (MN 4555-V); one mid-posterior caudal vertebra (MN 4560-V); one posterior caudal vertebra (MN 4556-V); one posterior caudal vertebra (UFRJ-DG 58-R/10); four chevrons (UFRJ-DG 58-R/2; 58-R/3; 58-R/4; 58-R/5); four chevrons (MN 4564-V); an ilium (UFRJ-DG 58-R/ 1); a partial pubis (MN s/n(-V); and three ribs (MN 4562-V). ...
... Amazonsaurus Carvalho, Avilla and Salgado 2003 Amazonsaurus maranhensis Carvalho, Avilla and Salgado 2003 Holotype Two dorsal neural spines (MN 4558-V; UFRJ-DG 58-R/9); two dorsal centra (MN 4559-V; MN s/n(-V); neural spine of anterior caudal vertebra (UFRJ-DG 58-R/7) (Fig. 2); one mid-caudal vertebra (MN 4555-V); one mid-posterior caudal vertebra (MN 4560-V); one posterior caudal vertebra (MN 4556-V); one posterior caudal vertebra (UFRJ-DG 58-R/10); four chevrons (UFRJ-DG 58-R/2; 58-R/3; 58-R/4; 58-R/5); four chevrons (MN 4564-V); an ilium (UFRJ-DG 58-R/ 1); a partial pubis (MN s/n(-V); and three ribs (MN 4562-V). ...
With 17 species formally identified throughout the world, Rebbachisauridae is, at present, the best-represented group of South American diplodocoids, and it has a temporal record ranging from the Barremian up to the Turonian. Defined as all diplodocoids more closely related to Rebbachisaurus garasbae than to Diplodocus carnegii, these sauropods are characterized by postcranial synapomorphies (e.g., absence of the hyposphenal ridge on anterior caudal vertebrae; presence of spinodiapophyseal lamina in caudal vertebrae). Although relatively complete skulls are known in only a few genera (Limaysaurus, Lavocatisaurus, and Nigersaurus), the whole cranial evidence indicates that they were highly specialized with respect to other diplodocoids (for instance Diplodocidae). South America counts ten genera of Rebbachisauridae, most of them from the Argentine Patagonia. They embrace a rather diverse group of basally branching forms (Amazonsaurus, Zapalasaurus, Comahuesaurus, and Lavocatisaurus), derived forms (as the limaysaurines Limaysaurus and Cathartesaura and the rebbachisaurines Katepensaurus and Itapeuasaurus), together with forms of uncertain phylogenetic filiation (Rayososaurus). Rebbachisaurids were important in South America toward the end of the Early Cretaceous, integrating, at that time, the sauropod faunas together with macronarians (Titanosauriformes) and other diplodocoids (Dicraeosauridae). They persisted up to at least the Turonian, being the last diplodocoids in becoming extinct globally.
... The third rebbachisaurid described is the rather fragmentary Amazonsaurus maranhensis (Carvalho et al. 2003), the first member of the clade undoubtedly from the Lower Cretaceous, and the first one recorded in Brazil, although it was not originally considered as a rebbachisaurid but as a basal diplodocoid. ...
... Amazonsaurus maranhensis Carvalho, Avilla and Salgado 2003 Holotype Two dorsal neural spines (MN 4558-V; UFRJ-DG 58-R/9); two dorsal centra (MN 4559-V; MN s/n(-V); neural spine of anterior caudal vertebra (UFRJ-DG 58-R/7) (Fig. 2); one mid-caudal vertebra (MN 4555-V); one mid-posterior caudal vertebra (MN 4560-V); one posterior caudal vertebra (MN 4556-V); one posterior caudal vertebra (UFRJ-DG 58-R/10); four chevrons (UFRJ-DG 58-R/2; 58-R/3; 58-R/4; 58-R/5); four chevrons (MN 4564-V); an ilium (UFRJ-DG 58-R/ 1); a partial pubis (MN s/n(-V); and three ribs (MN 4562-V). Diagnosis Small sauropod characterized by Carvalho et al. (2003) as having caudal neural spines that are straight and posteriorly inclined, with "lateral" laminae formed by the spinoprezygapophyseal and postzygodiapophyseal laminae which, at least in the most anterior ones, bend anteriorly in such a way that the anterior surface of the lamina is concave while the posterior surface is convex. ...
... Amazonsaurus maranhensis Carvalho, Avilla and Salgado 2003 Holotype Two dorsal neural spines (MN 4558-V; UFRJ-DG 58-R/9); two dorsal centra (MN 4559-V; MN s/n(-V); neural spine of anterior caudal vertebra (UFRJ-DG 58-R/7) (Fig. 2); one mid-caudal vertebra (MN 4555-V); one mid-posterior caudal vertebra (MN 4560-V); one posterior caudal vertebra (MN 4556-V); one posterior caudal vertebra (UFRJ-DG 58-R/10); four chevrons (UFRJ-DG 58-R/2; 58-R/3; 58-R/4; 58-R/5); four chevrons (MN 4564-V); an ilium (UFRJ-DG 58-R/ 1); a partial pubis (MN s/n(-V); and three ribs (MN 4562-V). Diagnosis Small sauropod characterized by Carvalho et al. (2003) as having caudal neural spines that are straight and posteriorly inclined, with "lateral" laminae formed by the spinoprezygapophyseal and postzygodiapophyseal laminae which, at least in the most anterior ones, bend anteriorly in such a way that the anterior surface of the lamina is concave while the posterior surface is convex. ...
After the extinction of rebbachisaurids during the Cenomanian–Turonian interval, titanosaurs were the only group of sauropods to face the K–Pg event. This same global pattern also holds for the end-Cretaceous (Campanian–Maastrichtian) titanosaur record in South America, where their remains can be found from southern Argentina to Ecuador, with more frequent findings in Argentina and Brazil. In this chapter, we review these fossil findings and the main aspects of the taxonomy, systematics, and paleogeographic implications of this record and briefly discuss the importance of these occurrences for the understanding of titanosaur evolution. The diversity and abundance of end-Cretaceous titanosaur taxa in South America represent about 25% of the known Titanosauria species in the world, which makes them the most common group of large terrestrial herbivores of that time. Cretaceous titanosaurs from South America also vary highly in morphology and size, comprising small to large-sized taxa, for example. Their record mainly consists of appendicular and axial remains, including rare skull material, but also comprises eggs, nests, footprints, and coprolites. In South America, by the end of the Late Cretaceous, titanosaurs were generally represented by more derived titanosaurians that are mainly taxonomically assigned to more derived species within Aeolosaurini and Saltasaurinae.
... The world sauropod bone record shows diverse sauropods preserved in different environments (e.g., Sanz et al., 1987Sanz et al., , 1999Smith et al., 2001;Carvalho et al., 2003;González Riga and Astini, 2007;González Riga et al., 2008;Zaher et al., 2011;Le Loeuff et al., 2013;González Riga et al., 2016;Otero et al., 2021;González Riga et al., 2021). Given that both continental and coastal environments have a high preservation potential, the almost exclusive South American record of sauropod bones in continental environments (as well as most of their tracks) not only supports our hypothesis of the existence of an ecological relationship between sauropods and a particular environment but also shows that it does not respond to a preservation bias. ...
... Late Berriasian -Valanginian (Leanza and Hugo, 1997) Bajadasaurus pronuspinax It is composed of fine-grained sandstones with interbedded argillaceous and carbonate levels. The depositional environment is considered to have been marine in the northern portion, changing to lacustrine and floodplain in the southern part of the basin (Gonçalves and Carvalho, 1996;Carvalho et al., 2003). ...
... Amazonsaurus maranhensis Carvalho, Avilla and Salgado, 2003 Diplodocoidea ...
The ichnological Cretaceous sauropod record of South America is analyzed for the first time in relation with skeletal and paleoenvironmental data. The updated database includes 39 tracksites and 71 valid species (53 titanosaurs and 18 non-titanosaurs) from Colombia, Ecuador, Peru, Chile, Brazil and Argentina. The track and bone records analyzed evidence a relationship with continental environments, specifically with fluvial ones. This is observed in all Sauropoda records, indicating an ecological association of the Cretaceous sauropods for these environments. In addition, the paleogeographic reconstruction integrating these records does not evidence any correlation between the distribution of sauropods and the latitudinal range. During the late Campanian–Maastrichtian interval, when the Atlantic transgression event was established, the titanosaur record started to show a singular panorama. The tracksites are preserved not only in continental paleoenvironments but also in marginal-marine ones, being the only last records of titanosaurs associated with that environment in South America. Both the paleoecological aspects based on sauropod Cretaceous record and the paleoenvironmental data collected in this work support the hypothesis that these tracksites were used by titanosaurs as ‘transit areas’ to move among the environments they inhabited.
... In the analysis of Whitlock [54], this character was hypothesized as a synapomorphy of Amargasaurus + more derived dicraeosaurids and Rebbachisaurinae (= "Limaysaurinae") + Nigersaurinae. Among rebbachisaurids, the transverse processes on the anterior caudal vertebrae are directed laterally only in Amazonsaurus [32]. In other taxa, the ventral margin of the transverse process is dorsolaterally directed: Comahuesaurus [33], Demandasaurus [27], Itapeusaurus [41], Katepensaurus [45], Lavocatisaurus [35], Limaysaurus [44], Tataouinea [36], the Bajo Barreal rebbachisaurid [47], the Kem Kem rebbachisaurid [48], and the Wessex rebbachisaurid [49]. ...
... The TPRL is absent but the prezygapophyses contact each other ventrally in Comahuesaurus [33], Demandasaurus [27], Nigersaurus [13], the Kem Kem rebbachisaurid [48], and the Wessex rebbachisaurid [49]. The TPRL is absent, the ventral margins of prezygapophyses are separated, and the PRSL extends to the roof of the neural canal in Dzharatitanis and Amazonsaurus [32]. ...
... The postzygapophyses contact each other ventrally on the anterior caudals in Comahuesaurus [33], Demandasaurus [27], Itapeusaurus [41], Limaysaurus [44], Nigersaurus [13], Tataouinea [36], the Bajo Barreal rebbachisaurid [47], and the Wessex rebbachisaurid [49]. The postzygapophyses are separated ventrally in Dzharatitanis, Amazonsaurus [32], Cathartesaura [46], and Katepensaurus [45]. ...
Dzharatitanis kingi gen. et sp. nov. is based on an isolated anterior caudal vertebra (USNM 538127) from the Upper Cretaceous (Turonian) Bissekty Formation at Dzharakuduk, Uzbekistan. Phylogenetic analysis places the new taxon within the diplodocoid clade Rebbachisauridae. This is the first rebbachisaurid reported from Asia and one of the youngest rebbachisaurids in the known fossil record. The caudal is characterized by a slightly opisthocoelous centrum, ‘wing-like’ transverse processes with large but shallow PRCDF and POCDF, and the absence of a hyposphenal ridge and of TPRL and TPOL. The neural spine has high SPRL, SPDL, SPOL, and POSL and is pneumatized. The apex of neural spine is transversely expanded and bears triangular lateral processes. The new taxon shares with Demandasaurus and the Wessex rebbachisaurid a high SPDL on the lateral side of the neural spine, separated from SPRL and SPOL. This possibly suggests derivation of Dzharatitanis from European rebbachisaurids. This is the second sauropod group identified in the assemblage of non-avian dinosaurs from the Bissekty Formation, in addition to a previously identified indeterminate titanosaurian.
... Fine-grained sandstones with interbedded argillaceous and carbonate levels, the Itapecuru Formation, represents the youngest Cretaceous of the Parnaíba Basin. The depositional environment is considered to have been marine in the northern portion, changing to lacustrine and floodplain environments in the southern part of the basin (Carvalho et al., 2003). ...
... The layers display a lenticular to tabular geometry, with thicknesses varying from 0.5 to 3.0 m, and palaeocurrents trending southwest. In a vertical profile, the muddy facies grade up into sandy deposits in a clear coarsening-upward pattern (Carvalho et al., 2003). This coarsening-upward cycle at Mata is part of a 3 m thick sequence that is interpreted as a fluvial-deltaic progradation in lacustrine conditions during Aptian-Albian times (Gonçalves and Carvalho, 1996). ...
... Lithofacies of Mata locality (Itapecuru-Mirim County, Maranhão State) and the fossiliferous strata where the new taxa was found (Modified fromCarvalho et al., 2003). ...
The new Pleurodira turtle Itapecuruemys amazonensis gen. et sp. nov. from the Itapecuru Formation (Parnaíba
Basin, Brazil) is described. The new species is represented only by its holotype, which consists of an almost
complete carapace and plastron, with an oval-shaped outline. The most peculiar characters of Itapecuruemys
amazonensis are: neural plates six and seven are separated by costal six, and the seventh neural plate contacts the
sixth, seventh and eighth costal plates and a suprapygal. The phylogenetic hypothesis proposed in this paper
suggests that Itapecuruemys amazonensis, together with Cearachelys and Galianemys spp., form a monophyletic
assemblage and also widen the paleoherpetological diversity of the Itapecuru Formation in the Parnaíba Basin
(Brazil).
... In Brazil, the sole occurrence of the group so far is at São Luís Basin (Northeastern Brazil), with two nominal species: Amazonsaurus maranhensis Carvalho et al. (2003) and Itapeuasaurus cajapioensis Lindoso et al. (2019) (Carvalho et al., 2003;Medeiros and Schultz, 2004;Castro et al., 2007;Medeiros et al., 2014;Lindoso et al., 2019). ...
... In Brazil, the sole occurrence of the group so far is at São Luís Basin (Northeastern Brazil), with two nominal species: Amazonsaurus maranhensis Carvalho et al. (2003) and Itapeuasaurus cajapioensis Lindoso et al. (2019) (Carvalho et al., 2003;Medeiros and Schultz, 2004;Castro et al., 2007;Medeiros et al., 2014;Lindoso et al., 2019). ...
... The Potiguar basin specimens have a combination of characteristics shared with some rebbachisaurid taxa (Fig. 4): (i) the articular facets of all specimens are sub-hexagonal to sub-quadrangular as seen in Demandasaurus (Fernández-Baldor et al., 2011); (ii) these facets bear a wide base as seen in Limaysaurus and Amazonsaurus (Gallina and Apesteguía, 2005); (iii) the centra present an amphicoelic condition present is most rebacchisaurids (Carvalho et al., 2003;Canudo et al., 2018); (iv) the centra lack pneumatization, a character shared with most rebbachisaurids, except for the Tunisian Tatouinea (Fanti et al., 2013); (v) an anterior position of the neural arch is implied by the anteriorly located centroneural suture of the centrum (Salgado et al., 1997;Wilson and Sereno, 1998;Canudo et al., 2018). ...
... Historically, this succession has also been regarded as the Alcântara Member of the Itapecuru Formation, which is predominantly formed by continental deposits extending over most of the northern territory of Maranhão State, markedly along the Itapecuru river valley (Fig. 1). These Cretaceous deposits spans from the late Aptian to the early Late Cretaceous (Mesner & Wooldridge 1964;Campbell 1949;Pedrão et al. 1993a, b;Vicalvi & Carvalho 2002;Carvalho et al. 2003). We consider the studied succession as the Alcântara Formation (sensu Cunha 1968), which concordantly overlies the Itapecuru Formation. ...
... They also included the Aptian-Albian strata that crops out along the Itapecuru river valley and the upper succession, including the Cenomanian levels of the Alcântara region in the so called Itapecuru Group , Rossetti 2001, assuming the Cenomanian strata as the Alcântara Formation (sensu Cunha 1968). Nonetheless, traditionally the São Luís Basin has been considered as a small coastal independent basin and the so called Grajaú Basin is assumed as the northern portion of the Parnaíba Basin (see Klein & Ferreira 1979;Vicalvi & Carvalho 2002;Carvalho 1995Carvalho , 2001Carvalho et al. 2003, Pessoa & Borghi 2005, Pedrão et al. 2003. ...
... It seems that the diplodocoids were dominant amongst the sauropods in the beginning of the Cenomanian in northeastern South America. The only two partially preserved skeletons of Cretaceous sauropods found thus far are of Diplodocoid -Amazonsaurus maranhensis, in the Itapecuru river valley (Itapecuru Formation), and the specimen of Itapeua Beach, at Cajapió (Carvalho et al. 2003. In contrast, sauropod teeth (Fig. 3E) are very rare in the same deposits where vertebrae were collected, what is interpreted as a taphonomic bias. ...
The Cretaceous Period is represent- ed in the northern region of Maranhão State by Ap- tian-Albian deposits cropping out inland and by the Cenomanian succession that is seen along the shore- line in the area of Golfão Maranhense (Large Maran- hão Gulf). This region had its sedimentation process- es controlled by tectonism related to the evolution of the continental margin. The Alcântara Formation is a sedimentary succession deposited in the northern coast of Maranhão state territory. It yielded a diverse fossil record, including plants and vertebrates. Based on the geologic and paleontologic evidences, the pa- leoclimate inferred for the studied region was mark- edly seasonal, with a stormy short season followed by a long dry season, eventually resulting in severe droughts. The fossils collected and studied revealed the biota that lived in northeastern South America in the early Cenomanian including conifers, giant ferns and a diverse community of vertebrates represented by fishes, crocodiles, pterosaurs and dinosaurs.
... This diversity has been also complemented by a few cranial remains (Calvo and Salgado, 1995;Carabajal et al., 2016;Canudo et al., 2018). Other records of Rebbachisauridae in South America occur only in northern-northeastern Brazil (Carvalho et al., 2003;Medeiros and Schultz, 2004;Castro et al., 2007;Medeiros et al., 2014). ...
... In the Parnaíba sedimentary Province (which also include the São Luís Basin to the north), Diplodocoidea remains has been found in a better preservation state, with a unique nominal species described so far, Amazonsaurus maranhensis Carvalho et al. (2003). This rebbachisaurid was described based on a partial postcranial skeleton in Lower Cretaceous (Aptian-Albian) strata of the Itapecuru Formation, southern Maranhão State, northern Brazil (Carvalho et al., 2003). ...
... In the Parnaíba sedimentary Province (which also include the São Luís Basin to the north), Diplodocoidea remains has been found in a better preservation state, with a unique nominal species described so far, Amazonsaurus maranhensis Carvalho et al. (2003). This rebbachisaurid was described based on a partial postcranial skeleton in Lower Cretaceous (Aptian-Albian) strata of the Itapecuru Formation, southern Maranhão State, northern Brazil (Carvalho et al., 2003). Many common taxa are recorded in the Alcântara and Itapecuru formations (e.g. ...
A new genus and species of Rebbachisauridae sauropod from the Cenomanian of the São Luís Basin, Alcântara Formation, Itapeuasaurus cajapioensis gen. et sp. nov., is described, the first from this temporal interval in northern Brazil. It is characterized by the presence of large and deep fossae on ventro-lateral aspect of the dorsal neural arch split by laminae obliquely oriented; posterior centrodiapophyseal lamina forked ventrally forming the dorsal edge of the centrodiapophyseal fossa; dorsal and ventral components of anterior caudal transverse process thinner than the usual bony bar. This latter feature is associated with the presence of a prezygodiapophyseal centrodiapophyseal fossa accessory lamina. The phylogenetic analysis performed herein identifies the subclade Nigersaurinae as a South American – African/European clade, suggesting a vicariant event before Cenomanian times. In addition, continental vertebrate taxa recorded in the Alcântara Formation offer support to a minor evolutionary change after major vicariant event in Western Gondwana.
... Two main features are indicative of the position of this remain within the anterior caudal series: first, the lateral laminae are slightly curved anteriorly, as they are in other Rebbachisauridae anterior caudal vertebrae (e.g. Amazonsaurus maranhensis (Carvalho et al., 2003) and Rebbachisaurus garasbae (Wilson & Allain, 2015)); second, the spinodiapophyseal laminae has an anterior crest, as seen in anterior caudal vertebrae of Amazonsaurus maranhensis (Carvalho et al., 2003), Rebbachisaurus garasbae (Wilson & Allain, 2015), and Tataouinea hannibalis (Fanti et al., 2015), which is the result of the fusion of the spinoprezigapophyseal laminae that, from the bottom of the neural spine, develops upward until joining to the spinodiapophyseal lamina at the midportion of the neural spine. At the base of the neural spine the laminae are less slender and get more robust towards the top. ...
... Two main features are indicative of the position of this remain within the anterior caudal series: first, the lateral laminae are slightly curved anteriorly, as they are in other Rebbachisauridae anterior caudal vertebrae (e.g. Amazonsaurus maranhensis (Carvalho et al., 2003) and Rebbachisaurus garasbae (Wilson & Allain, 2015)); second, the spinodiapophyseal laminae has an anterior crest, as seen in anterior caudal vertebrae of Amazonsaurus maranhensis (Carvalho et al., 2003), Rebbachisaurus garasbae (Wilson & Allain, 2015), and Tataouinea hannibalis (Fanti et al., 2015), which is the result of the fusion of the spinoprezigapophyseal laminae that, from the bottom of the neural spine, develops upward until joining to the spinodiapophyseal lamina at the midportion of the neural spine. At the base of the neural spine the laminae are less slender and get more robust towards the top. ...
... The Family Rebbachisauridae currently comprises 13 species formally described (Wilson & Allain, 2015). So far, only one species is known for Brazilian strata, Amazonsaurus maranhensis Carvalho et al. (2003), which is represented by dorsal, sacral, and caudal vertebrae, chevrons, pubis, and ilium. Additionally, Rebbachisauridae isolated and fragmentary axial remains were also reported by Medeiros & Schultz (2004) and Castro et al. (2007). ...
The vertebrate fossil record from the Quiricó Formation, Sanfranciscana Basin (Lower Cretaceous), is scarce, but the remains yet found are of great importance for the understanding of the paleobiogeographic and biogeographic processes that took place during the initial stages that led to the opening of the Atlantic Ocean. In this work, new occurrences of sauropod dinosaur bones and theropod teeth from the Barremian–Aptian Quiricó Formation, collected in Campo Azul and Olhos D'Água, State of Minas Gerais, Brazil, are described. The fossils comprise isolated bones of sauropod dinosaurs, such as fragments of sauropod vertebrae, and isolated theropod teeth, both preserved in lacustrine siltstones and associated sandstones. The anatomical features of the sauropod bones suggest that they can be assigned to Rebbachisauridae and the morphological analysis of the isolated theropod teeth placed them within Abelisauridae and Carcharodontosauridae. This suggests that during the Early Cretaceous, the dinosaurian fauna from the southeastern Brazil was more closely related to African faunas than to other South-American ones.
... The fossil record of South American sauropods from the Lower Cretaceous is relatively reduced, including 10 species (Appendix). In Argentina sauropod species from strata of the Neuqu en and San Jorge Basins; in Brazil these dinosaurs were found in São Luís-Grajaú and Sanfranciscana basins (Carvalho et al., 2003;Zaher et al., 2011). ...
... The nemegtosaurid titanosaur Tapuiasaurus macedoi (Zaher et al., 2011) was recovered from the Aptian Quiric o Formation, Areado Group (Sanfranciscana Basin). The Albian Itapecuru Group (São Luís-Grajaú Basin) is an important dinosaur-bearing unit in northern Brazil from which was found the rebbachisaurid Amazonsaurus maranhensis (Carvalho et al., 2003) and other indeterminate dinosaur remains. ...
... Against this statistical data from Argentinean sedimentary basins, in Brazil the sauropod fossils are preserved in facies association regarded as part of the Lowstand System Tract. It could be observed in the Early Cretaceous the fluvial dominated lacustrine deltaic sandstone facies of Quiric o Formation (Aptian), Areado Group in Sanfranciscana Basin (Campos and Dardenne, 1997;Zaher et al., 2011), and in deltaic mounth bar sandstone facies of Aptian Itapecuru Group (Lima and Rossetti, 1999;Carvalho et al., 2003;Miranda and Rossetti, 2006) and deltaic conglomeratic facies of Albian-Cenomanian Alcântara Formation (Medeiros et al., 2007;Candeiro et al., 2011) in São Luís-Grajaú Basin. In the Late Cretaceous, channel filling conglomerates and sandstones facies and flash floods conglomeratic sandy facies of the Adamantina, Presidente Prudente and Marília formations (SantonianeMaastrichtian), Bauru Group, Paran a Basin (Soares et al., 1980) and in the conglomeratic sandstones of fluvial to distal alluvial fan facies of Utiariti Formation (Campanian-Maastrichtian), Parecis Group, Rio das Mortes Rift (Chapada Graben) in north Paran a Basin (Weska, 2006). ...
Rests of Aeolosaurus colhuehuapensis, a titanosaur from the Colhué Huapi lake, in the southern Chubut Province, Argentina, were analyzed. The materials under study include twenty one caudal vertebrae and seven haemal arches. They were recovered articulated in overbank facies related to deposits of multi-channel fluvial systems of high sinuosity in the informally called "strata of the Colhué Huapi lake" of Campanian-Maastricthian age. These systems displayed important seasonal fluctuations in the paleodischarge and they were encompassed in a semi-arid climate. The taphonomic history was inferred from the analysis of several taphonomic characteristics present in the bones and macro- and microscopic sedimentologic observations. The presence of tenuous longitudinal striation, the absence of bone exfoliation, the articulate condition of the materials and the dorsal bow of the caudal series, support a short period of subaerial exposure with a rapid burial episode. The absence of abrasion marks in the materials indicates that they had scarce or null transport; therefore, they could be considered as autochthonous. The dorsal bow of the tail shows an opisthotonus posture, also exhibited by some theropod and sauropod dinosaurs, but undocumented in the Chubut Group. The recent fluctuant climatic conditions, with variations of extreme humidity and drought, strongly affected the preservation of the materials. The present work is the first detailed taphonomic study of a dinosaur preserved in proximal floodplain facies for the Chubut Group. Finally, the preservation of sauropod bones in those facies is relevant because this type of sub-environment possess a high rate of sediment input as well as scarce or null re-working of the skeletal remains, which favor the conservation of articulated skeletal elements. These findings are very important for the taphonomic and phylogenetic analysis of the titanosaur clade, in which the majority of the taxa are represented by isolated and unarticulated remains.
... The fossil record of South American sauropods from the Lower Cretaceous is relatively reduced, including 10 species (Appendix). In Argentina sauropod species from strata of the Neuqu en and San Jorge Basins; in Brazil these dinosaurs were found in São Luís-Grajaú and Sanfranciscana basins (Carvalho et al., 2003;Zaher et al., 2011). ...
... The nemegtosaurid titanosaur Tapuiasaurus macedoi (Zaher et al., 2011) was recovered from the Aptian Quiric o Formation, Areado Group (Sanfranciscana Basin). The Albian Itapecuru Group (São Luís-Grajaú Basin) is an important dinosaur-bearing unit in northern Brazil from which was found the rebbachisaurid Amazonsaurus maranhensis (Carvalho et al., 2003) and other indeterminate dinosaur remains. ...
... Against this statistical data from Argentinean sedimentary basins, in Brazil the sauropod fossils are preserved in facies association regarded as part of the Lowstand System Tract. It could be observed in the Early Cretaceous the fluvial dominated lacustrine deltaic sandstone facies of Quiric o Formation (Aptian), Areado Group in Sanfranciscana Basin (Campos and Dardenne, 1997;Zaher et al., 2011), and in deltaic mounth bar sandstone facies of Aptian Itapecuru Group (Lima and Rossetti, 1999;Carvalho et al., 2003;Miranda and Rossetti, 2006) and deltaic conglomeratic facies of Albian-Cenomanian Alcântara Formation (Medeiros et al., 2007;Candeiro et al., 2011) in São Luís-Grajaú Basin. In the Late Cretaceous, channel filling conglomerates and sandstones facies and flash floods conglomeratic sandy facies of the Adamantina, Presidente Prudente and Marília formations (SantonianeMaastrichtian), Bauru Group, Paran a Basin (Soares et al., 1980) and in the conglomeratic sandstones of fluvial to distal alluvial fan facies of Utiariti Formation (Campanian-Maastrichtian), Parecis Group, Rio das Mortes Rift (Chapada Graben) in north Paran a Basin (Weska, 2006). ...
... In posterior view, the postzygapophysis are fused one to another to form a single articular surface ( Figure 1F). The posterior median AMNH 594, 614, 694, 5855;CM 84, 94, 307, 2098CM 84, 94, 307, , 2099USNM 2672USNM , 2673 Carvalho et al. (2003) Cathartesaura anaerobica ...
... There is no evidence of cameras separated by horizontal septa such as in Tataouinea (Fanti et al. 2015). However, pneumatic chambers are common in Rebbachisauridae like in Amazonsaurus, Tataouinea and Sidersaura (Carvalho et al. 2003;Fanti et al. 2015;Lerzo et al. 2024). The ischial peduncle is relatively longer than wide and does not project posteriorly beyond the iliac blade. ...
... The dinosaur fossil record from Cretaceous Brazil is especially rich, with about 25 valid genera having been described until recently (Arid and Vizotto 1971;Kellner and Campos 1996;Martill et al. 1996;Kellner 1999, 1999;Kellner and Azevedo 1999;Kellner and Campos 2002;Carvalho et al. 2003;Naish et al. 2004;Kellner et al. 2005Kellner et al. , 2006Salgado and Carvalho 2008;Zaher et al. 2011;Bandeira et al. 2016;Carvalho et al. 2017;Delcourt and Iori 2018;Langer et al. 2019;Lindoso et al. 2019;Sayão et al. 2020;Zaher et al. 2020;Brum et al. 2021;Iori et al. 2021;Souza et al. 2021;Silva-Junior et al. 2022). Up to this date, many studies have aimed at reviewing and cataloguing this known dinosaur diversity in Brazil (Kellner 1996;Bittencourt and Langer 2011;Medeiros et al. 2014;Brusatte et al. 2017;Sales, Martinelli et al. 2017), with most of them focusing mainly on the possible palaeobiogeographic implications Brusatte et al. 2017). ...
... The Itapecuru Formation (Aptian-Albian), despite having a much humbler dinosaur record in comparison to the aforementioned formation (n = 62; Table 1), displays a proportionally high incidence of isolated teeth (n = 31; 50%) (Ferreira et al. 1992;Ribeiro et al. 2003). A few studies have discussed the dinosaur record of the Itapecuru Formation, normally focusing on particular groups such as Spinosauridae and Rebbachisauridae (Carvalho et al. 2003, França et al. 2021 and their specific distributions. While our results show a notably high percentage of dinosaur teeth, further studies on the taphonomy of this region must be done in order to better understand this preservation bias. ...
Dinosaur fossils are commonly found in Brazilian Mesozoic strata, with teeth being frequently found in Cretaceous outcrops. Many studies have been made with the aim of reviewing the known diversity of Brazilian dinosaurs, mostly focusing solely on their palaeobiogeography. However, few tried to typify these body fossils in order to see which kinds were most prevalent in the fossil record. This study aims to count and identify all occurrences of non-avian dinosaur teeth (isolated or in situ) unearthed from Brazilian Cretaceous strata in order to objectively measure their representativity in the national fossil record. Our literature search showed that almost half of the dinosaur fossil record from the Cretaceous of Brazil is composed by teeth, those being particularly abundant in the Alcântara, Adamantina and Marília formations. Theropod teeth are more abundant in comparison to sauropod teeth, with spinosaurids, deinonychosaurs, and abelisaurids being amply found. Despite representing a large share of the Brazilian fossil record, dinosaur teeth have only recently been studied in depth, with many specimens being reassessed through the current identification methods. Other aspects besides primary taxonomic identification can also be further explored using the latest technologies on dinosaur teeth, allowing a deeper understanding of the palaeobiology of these reptiles.
... Deposition of the Itapecuru Formation took place in a plan fluvial meandering system and also comprises lakes and deltaic deposits from the end of Aptian to the middle Albian (Mesner and Wooldridge 1964;Pedrão et al. 1993aPedrão et al. , 1993bCarvalho et al. 2003;Pessoa and Borghi 2005;Miranda and Rossetti 2006;Ferreira et al. 2013Ferreira et al. , 2020Corrêa-Martins 2019). Faunal records have corroborated this environmental interpretation, such as freshwater Semionotiformes (Dutra and Malabarba 2001), Hybodontid sharks (Dutra and Malabarba 2001;Medeiros et al. 2014), and Coelacanthiformes Mawsoniidae, which points to the existence of large freshwater bodies in northern Maranhão State during the middle Cretaceous (Carvalho 2002;Medeiros et al. 2011). ...
... However, abrasion along the surface of CPHNAMA VT-1446-A, a commonly reported aspect of material recovered from the Itapecuru Formation (e.g. Carvalho et al. 2003;Castro et al. 2007), hampers the interpretation of the amount and outline of such marks. Maganuco and Dal Sasso (2018) have also noticed a medial low ridge between these pits in some pedal unguals (FSAC-KK 11888 and MPCM 13574). ...
Despite being poorly known from limited skeletal remains as teeth and a few postcranial material, spino-saurid remains have been reported from two different Lower Cretaceous localities in Brazil, with three officially proposed taxa up to now: Angaturama, Irritator and Oxalaia. Here, we report the first record of a spinosaurid pedal ungual from the Itapecuru Formation, Parnaíba Basin, Lower Cretaceous rocks of Maranhão State. The specimen retains a quite flat ventral surface that is proportionally almost two times broader than its proximal depth, which is a feature also found in Spinosaurus. Moreover, size inferences are made for this immature specimen.
... Recent years have seen major advances in what is known of the anatomy and palaeogeographical distribution of the rebbachisaurids, both in South America (Carvalho et al. 2003;Gallina and Apesteguía 2005;Carballido et al. 2012;Ibiricu et al. 2013) and Africa (Sereno et al. 1999;Fanti et al. 2013), as well as their unexpected presence in Europe (Pereda Suberbiola et al. 2003;Mannion 2009;Torcida-Baldor et al. 2011). These discoveries have allowed the rebbachisaurids to be placed beyond question at the base of the radiation of the diplodocimorph diplodocoids, and in all the phylogenies they are grouped in a clade that is clearly differentiated from the rest of the diplodocimorphs (e.g., Calvo and Salgado 1995;Wilson and Allain 2015;Tschopp et al. 2015). ...
... Rebbachisauridae.-As in most previous analyses, Amazonsaurus was recovered at the base of Rebbachisauridae (e.g., Mannion et al. 2012;Carballido et al. 2012;Torcida-Baldor et al. 2011), a position slightly different from that suggested by some previous works (e.g., Carvalho et al. 2003;Salgado et al. 2006;Carballido et al. 2010). Rebbachisauridae are here supported by the same three synapomorphies recently obtained by Wilson and Allain (2015): character 241, absence of the hyposphenal ridge on anterior caudal vertebrae (reversed in Demandasaurus and Tataouinea); character 244, presence of spinodiapophyseal lamina (convergently present in Lognkosauria; Carballido et al. 2017); character 250, middle caudal vertebrae with a flat ventral surface; and character 413, middle caudal vertebrae with anterodorsally oriented prezygapophyses (reverted in Lavocatisaurus and more derived rebbachisaurids (MDR). ...
Rebbachisaurids are a group of basal diplodocimorph sauropods that diversified in Gondwana at the end of the Early Cretaceous and the beginning of the Late Cretaceous. It is a group of great palaeobiogeographical interest, for it clearly illustrates various processes of dispersal throughout Gondwana and to Laurasia prior to the breakup of Africa and South America. However, the relationships within the group are still under discussion owing to the scarcity of cranial material that would help clarify them. In the present paper we describe the new rebbachisaurid Lavocatisaurus agrioensis gen. et sp. nov. from the Aptian-Albian (Lower Cretaceous) of Neuquén (Argentina). Remains have been recovered belonging to an adult specimen (holotype) and two immature specimens (paratypes). Taken together, almost all the bones of the taxon are represented, including most of the cranium. Lavocatisaurus agrioensis gen. et sp. nov. is the first rebbachisaurid from Argentina with an almost complete cranium, making it possible to recognize differences with respect to other rebbachisaurids, such as the highly derived Nigersaurus. Among its most notable characters are the presences of a large preantorbital fenestra and maxillary teeth that are significantly larger than those of the dentary. Our phylogenetic study places Lavocatisaurus amongst basal rebbachisaurids, as the sister lineage to Khebbashia (the clade formed by Limaysaurinae + Rebbachisaurinae). This position, which is somewhat more derived than that previously suggested for Comahuesaurus and Zapalasaurus (the Argentinean rebbachisaurids closest in geographical and geological terms), reaffirms the presence of different basal rebbachisaurid lineages in the Early Cretaceous of Patagonia.
... axial skeleton of Katepensaurus displays a suite of hypothesized pneumatic features that are, in most respects, comparable to those seen in other rebbachisaurid taxa. For instance, the dorsal vertebral centra of this Patagonian form are excavated by well-defined lateral fossae ("pleurocoels"), a feature that is shared with many other sauropods, including all other rebbachisaurids for which this part of the skeleton has been described (i.e., Amazonsaurus maranhensis, Carvalho et al. 2003, Comahuesaurus windhauseni, Carballido et al. 2012, Demandasaurus darwini, Torcida Ferná ndez-Baldor et al. 2011, Histriasaurus boscarollii, Dalla Vecchia 1999, Limaysaurus tessonei, Calvo and Salgado 1995, Nigersaurus taqueti, Sereno et al. 2007, Nopcsaspondylus alarconensis, Nopcsa 1902 Katepensaurus offers additional, compelling evidence that the dorsal series of at least some rebbachisaurids was pneumatized by diverticula from the pulmonary system. As detailed above, the middle to posterior dorsal neural arches of this Patagonian taxon display features that have not been documented elsewhere within Sauropoda, most notably the laterodiapophyseal fenestrae and their associated intradiapophyseal chambers. ...
... Fanti et al. (2015: 39) also reported ischial pneumaticity in Rebbachisaurus, but this was not mentioned by Wilson and Allain (2015) in their detailed redescription of this taxon, so the condition in this animal remains unclear. Lastly, Carvalho et al. (2003) reported a pneumatic chamber in the region of the ischial peduncle of the ilium of Amazonsaurus. Significantly, most recent phylogenetic analyses that have included this taxon (e.g., Carballido et al. 2012;Mannion et al. 2012;Fanti et al. 2015;Ibiricu et al. 2015;Wilson and Allain 2015) have recovered it as the earliest-diverging rebbachisaurid, suggesting that pelvic pneumaticity may be synapomorphic for, and therefore probably widespread within, this sauropod clade. ...
In dinosaurs and other archosaurs, the presence of foramina connected with internal chambers in axial and appendic-ular bones is regarded as a robust indicator of postcranial skeletal pneumaticity (PSP). Here we analyze PSP and its paleobiological implications in rebbachisaurid diplodocoid sauropod dinosaurs based primarily on the dorsal vertebrae of Katepensaurus goicoecheai, a rebbachisaurid from the Cenomanian–Turonian (Upper Cretaceous) Bajo Barreal Formation of Patagonia, Argentina. We document a complex of interconnected pneumatic foramina and internal chambers within the dorsal vertebral transverse processes of Katepensaurus. Collectively, these structures constitute a form of PSP that has not previously been observed in sauropods, though it is closely comparable to morphologies seen in selected birds and non-avian theropods. Parts of the skeletons of Katepensaurus and other rebbachisaurid taxa such as Amazonsaurus maranhensis and Tataouinea hannibalis exhibit an elevated degree of pneumaticity relative to the conditions in many other sauropods. We interpret this extensive PSP as an adaptation for lowering the density of the skeleton, and tentatively propose that this reduced skeletal density may also have decreased the muscle energy required to move the body and the heat generated in so doing. Given that several rebbachisaurids inhabited tropical to subtropical paleolatitudes during the extreme warmth of the mid-Cretaceous, increased PSP may have better enabled these sauropods to cope with extraordinarily high temperatures. Extensive skeletal pneumaticity may have been an important innovation in Rebbachisauridae, and perhaps also in saltasaurine titanosaurs, which evolved an even greater degree of PSP. This may in turn have contributed to the evolutionary success of rebbachisaurids, which were the only diplodocoids to survive into the Late Cretaceous.
... The Brazilian diplodocoid Amazonsaurus maranhensis (Carvalho et al., 2003) has been resolved by some phylogenetic analyses as a basal rebbachisaurid (Salgado et al., 2006;Sereno et al., 2007;Carballido et al., 2012;Mannion et al., 2012), or the outgroup to dicraeosaurids plus diplodocids (Salgado et al., 2004), or a basal diplodocoid (Whitlock 2011); other analyses excluded it altogether (Gallina and Apestegu ıa, 2005;Torcida Fern andez-Baldor et al., 2011). A single vertebra from the Early Cretaceous (Barremian) of Argentina was described as a "basal diplodocoid," but it could potentially be a rebbachisaurid (Apestegu ıa, 2007:536) based on the presence of an elongate parapophysis, which is shared by Rebbachisaurus (see below). ...
... observ.), Demandasaurus (Torcida Fern andez-Baldor et al., 2011; Torcida Fern andez-Baldor, 2012), Tataouinea (Fanti et al., 2013), and Amazonsaurus (Carvalho et al., 2003). The caudal neural spines of Rebbachisaurus differ in several ways from the posterior dorsal vertebrae available in our sample. ...
The holotype of the sauropod dinosaur Rebbachisaurus garasbae was discovered in infra-upper Cenomanian horizons of the Kem Kem region of southeastern Morocco in the 1940s and 1950s. The original materials included part of a vertebral column, some of which was found in articulation, and a scapula, a humerus, and an ischium. Of these remains, only the scapula and one of the dorsal vertebrae have been described, but in abbreviated form. Following complete preparation of the partial skeleton, careful examination and fitting of scores of fragments collected with these materials, and computed tomography imaging of the most complete vertebra, we present a complete description of the holotype of Rebbachisaurus garasbae. Our description identifies several autapomorphies of the dorsal and caudal vertebrae, both relating to the shape of the vertebrae and the architecture of their laminae. Based on our reassessment of its anatomy, Rebbachisaurus is recovered as a member of an Afro-European clade that includes Nigersaurus and Demandasaurus. Due to the large size of one of its dorsal vertebrae (ca. 1.45 m tall), Rebbachisaurus has been considered to be a large sauropod. The size of the vertebral centra and the length and cross-sectional area of the humerus of Rebbachisaurus, however, indicate this individual weighed 7915–12,015 kg, which is slightly larger than Amargasaurus but comparable in size to some individuals of Dicraeosaurus. The dorsal vertebrae of Rebbachisaurus and other rebbachisaurids have been suggested to be highly mobile, but results suggest that anatomical features of the vertebrae actually limited rotation and increased resistance to dorsoventrally directed forces applied to the transverse processes.
... These features resemble those described in the cervical ribs of the European rebbachisaurid Demandasaurus darwini (Pereda-Suberbiola et al., 2003;Torcida Fernández-Baldor et al., 2011). The slightly opisthocoelous condition of the centrum of UNPSJB-PV 1007/13 is shared with the anterior dorsal vertebrae of Amazonsaurus maranhensis (Carvalho et al., 2003; see also Mannion et al., 2012), Comahuesaurus (Salgado et al., 2004;Carballido et al., 2012), and MMCH-Pv 49 (Apesteguía et al., 2010;Haluza et al., 2012). In contrast, the anterior dorsal centra are strongly opisthocoelous in Limaysaurus (Calvo and Salgado, 1995). ...
... These conditions are shared with Comahuesaurus, Limaysaurus, and Nigersaurus. In the Brazilian taxon Amazonsaurus, by contrast, the dorsal centra are comparatively low and elongate (Carvalho et al., 2003). ...
Cretaceous outcrops in southern South America preserve a rich and evolutionarily important record of sauropod dinosaurs. Among Sauropoda, South American titanosaurs have garnered particular interest due to their abundance and taxonomic diversity. Nevertheless, the fossil record of rebbachisaurids has also improved significantly in recent years, and consequently so has knowledge of the group. However, many aspects of the anatomy and phylogenetic relationships of Rebbachisauridae remain unresolved, due in large part to the fragmentary nature of many members of the clade. Within this context, we describe new fossils of Katepensaurus goicoecheai Ibiricu, Casal, Martínez, Lamanna, Luna, and Salgado, a recently-named rebbachisaurid from the Upper Cretaceous (Cenomanian/Turonian) Bajo Barreal Formation of central Patagonia (Argentina). Based on these additional materials, we propose two new autapomorphies of this taxon: (1) ventral portion of posterior articular surface of anterior dorsal vertebral centrum wider than dorsal portion, conferring a ‘teardrop-shaped’ contour; and (2) ovoid fossa on dorsal aspect of anterior to middle dorsal vertebral transverse processes. These features enhance our understanding of morphological diversity within Rebbachisauridae and augment the diagnosis of Katepensaurus. Furthermore, phylogenetic analysis confirms the assignment of this taxon to the rebbachisaurid subclade Limaysaurinae. Katepensaurus is the southernmost record of a rebbachisaurid that is identifiable to the generic level.
... In the Brazilian context, in rocks of similar age to those of Rio do Peixe Basin, there is evidence of the occurrence of Diplodocoidea and Titanosauriformes sauropods (Carvalho et al. 2003(Carvalho et al. , 2017Salgado et al. 2006;Zaher et al. 2011;Ghilardi et al. 2016), which makes them the possible trackmakers of SJFE-A. In the Rio do Peixe Group, records of body fossils are rare, and those found so far are restricted to Titanosauriformes, described as early titanosaurs (Ghilardi et al. 2016;Carvalho et al. 2017), despite some authors disagree and associate them as possible non-titanosaurian titanosauriforms (Poropat et al. 2017). ...
Sauropods were a successful group of herbivorous dinosaurs that colonised all continents throughout the Mesozoic. At first glance, the organisms in this group present a conservative shape of quadrupedal animals with elongated necks and tails. However, there was great diversification in the morphology of sauropods, which is still poorly understood in detail, especially during the Early Cretaceous. In this study, we describe a new ichnosite dated from the earliest stages of the Cretaceous of Brazil. The site includes a well-preserved trackway of a large sauropod dinosaur, with manus and pes prints, as well as tracks of theropods and indeterminate tetrapods. The sauropod trackway shows a unique set of characteristics that allowed the erection of a new ichnogenus and ichnospecies, Sousatitanosauripus robsoni igen. nov. et isp. nov. The probable trackmaker was a Titanosauriformes with a mosaic of basal and advanced features, bringing new insights into the diversity and evolution of the group.
... Shipman 1981). The specimen NHM-PV R.2981(b) exhibits strongly concave lateral surfaces ( Figure 11A,D), as in the rebbachisaurids Amanzosaurus maranhensis Carvalho et al. 2003, Limaysaurus tessonei Calvo and Salgado 1995, and Itapeuasaurus cajapioensis Lindoso et al. 2019. In the anterior view, the centrum is strongly compressed medially and forms an 8-shaped outline, most by the development of deep blind fossae ( Figure 11E). ...
Supposed dinosaur remains were collected between 1859 and 1906 in the Lower Cretaceous Recôncavo Basin (Northeast Brazil). Since these materials remained undescribed, and most were considered lost. Recently, some of these historical specimens were rediscovered in the Natural History Museum of London, providing an opportunity to revisit them after 160 years. The specimens come from five different sites, corresponding to the Massacará (Berriasian-Barremian) and Ilhas (Valanginian-Barremian) groups. Identified bones comprise mainly isolated vertebral centra from ornithopods, sauropods, and theropods. Appendicular remains include a theropod pedal phalanx, humerus, and distal half of a left femur with elasmarian affinities. Despite their fragmentary nature, these specimens represent the earliest dinosaur bones discovered in South America, enhancing our understanding of the Cretaceous dinosaur faunas in Northeast Brazil. The dinosaur assemblage in the Recôncavo Basin resembles coeval units in Northeast Brazil, such as the Rio do Peixe Basin, where ornithopods coexist with sauropods and theropods. This study confirms the presence of ornithischian dinosaurs in Brazil based on osteological evidence, expanding their biogeographic and temporal range before the continental rifting between South America and Africa. Additionally, these findings reinforce the fossiliferous potential of Cretaceous deposits in Bahia State, which have been underexplored since their initial discoveries.
... Diplodocoid sauropods can be considered as the classic low-level browsers, with diplodocids and dicraeosaurids as an abundant component of large herbivorous fauna during the Late Jurassic across North America, Europe, and Gondwana, and also during the earliest Early Cretaceous in western Gondwana McPhee et al., 2016;Gallina et al., 2019). Nevertheless, the archetype of a groundlevel browser sauropod is represented by the rebbachisaurids, which survived (and partially replaced) the other families of diplodocoids, becoming an important component of the Cretaceous sauropod faunas in South America, Africa, and Europe until CenomanianeTuronian times (Lavocat, 1954;Calvo & Salgado, 1995;Bonaparte, 1996;Sereno et al., 1999;Carvalho et al., 2003;Torcida Fern andez-Baldor, F. et al., 2011;Mannion et al., 2011;Fanti et al., 2013). The highly derived design present in rebbachisaurids that tended towards low or ground-level browsing adaptations is indicative of feeding specialization, and probably, based on snout shape of Nigersaurus, generalist sauropods (Sereno et al., 2007). ...
A new titanosaur sauropod genus including an almost complete skull and axial elements to the hips, reflecting a convergent bauplan with the older rebbachisaurids sauropods.
... Dinosaur teeth, mainly theropods, are commonly collected in the Cretaceous strata of the Itapecuru Formation (which crops out extensively in the central, northern, and northeastern regions of Maranhão) and Alcântara Formation, with fossiliferous outcrops concentrated in the northern part of the state (Corrêa Martins, 1997;Carvalho et al., 2003;Medeiros & Schultz, 2001Lindoso et al., 2012;Medeiros et al., 2014Medeiros et al., , 2019Lindoso et al., 2012;Sousa et al., 2015;Letizio et al., 2022). Records of the Itapecuru Formation occur near Duque Bacelar, immediately west of the Parnaíba River Valley (CPRM, 2012); however, no fossiliferous occurrences have been reported. ...
This article shows the tectonic influence of the Parnaíba River Lineament located in the Parnaíba Basin through a paleontological finding of a Cretaceous age close to a Permian sequence. The studied region is in the northeast of the State of Maranhão, near the town of Duque Bacelar, in the vicinity of the lineament. A normal fault in the NNE-SSW direction was responsible for the lowering of the Itapecuru Formation strata (Cretaceous) and the relative upward movement of the Pedra de Fogo Formation (Permian). The unprecedented finding of a Mesozoic (mid-Cretaceous) theropod tooth located topographically at the same level as a Paleozoic unit represents evidence of tectonic activity affecting the stratigraphic successions of the Parnaíba Basin.
... Transitional Aptian-Albian deposits in both Brazil [164] and Argentina [165][166][167] are dominated by rebbachisaurids, although fragmentary remains belonging to titanosauriforms are also present in the Brazilian deposits [168], and the non-titanosaurian somphospondylan Chubutisaurus is present in Argentina [169][170][171]. Albian-aged deposits in Argentina show some variation. ...
The Upper Cretaceous Winton Formation of Queensland, Australia, has produced several partial sauropod skeletons, but cranial remains—including teeth—remain rare. Herein, we present the first description of sauropod teeth from this formation, based on specimens from three separate sites. An isolated tooth and a dentary fragment from the Diamantinasaurus matildae type locality are considered to be referable to that titanosaurian taxon. A single tooth from the D. matildae referred specimen site is similarly regarded as being part of that individual. Seventeen teeth from a new site that are morphologically uniform, and similar to the teeth from the two Diamantinasaurus sites, are assigned to Diamantinasauria. All sauropod teeth recovered from the Winton Formation to date are compressed-cone-chisel-shaped, have low slenderness index values (2.00–2.88), are lingually curved at their apices, mesiodistally convex on their lingual surfaces, and lack prominent carinae and denticles. They are markedly different from the chisel-like teeth of derived titanosaurs, more closely resembling the teeth of early branching members of the titanosauriform radiation. This provides further support for a ‘basal’ titanosaurian position for Diamantinasauria. Scanning electron microscope microwear analysis of the wear facets of several teeth reveals more scratches than pits, implying that diamantinasaurians were mid-height (1–10 m) feeders. With a view to assessing the spatio-temporal distribution of sauropod tooth morphotypes before and after deposition of the Winton Formation, we provide a comprehensive continent-by-continent review of the early titanosauriform global record (Early to early Late Cretaceous). This indicates that throughout the Early–early Late Cretaceous, sauropod faunas transitioned from being quite diverse at higher phylogenetic levels and encompassing a range of tooth morphologies at the start of the Berriasian, to faunas comprising solely titanosaurs with limited dental variability by the end-Turonian. Furthermore, this review highlights the different ways in which this transition unfolded on each continent, including the earliest records of titanosaurs with narrow-crowned teeth on each continent.
... Salgado et al. 2006, Apesteguía 2007, Carballido et al. 2012, Haluza et al. 2012, Ibiricu et al. 2012, Gallina et al. 2014, 2019, Rauhut et al. 2015. Within this group, Rebbachisauridae is a family of sauropod dinosaurs that lived from the early Cretaceous to the late Cretaceous of South America, Europe and Africa (Bonaparte 1997, Carvalho et al. 2003, Upchurch et al. 2004, Apesteguia et al. 2010, Whitlok 2011, Mannion & Barret 2013, Torcida Fernandez-Baldor et al. 2011. The family includes a dozen genera, from which Rayososaurus agrionensis (Bonaparte 1997, Carballido et al. 2010, Limaysaurus tessonei (= Rebbachisaurus tessonei in Calvo & Salgado 1995, Salgado et al. 2004, Cathartesaura anaerobica (Gallina & Apesteguía 2005), Nopcsaspondylus alarconensis (Apesteguía 2007), Comahuesaurus windhauseni (Carballido et al. 2012), Katepensaurus goicoecheai (Ibiricu et al. 2013(Ibiricu et al. , 2015, Zapalasaurus bonapartei (Salgado et al. 2006) and Lavocatisaurus agrioensis (Canudo et al. 2019) were registered in Argentina. ...
CT scans of the type braincase of Limaysaurus tessonei (MUCPv-205) allowed the first study of the endocranial cavities (brain and inner ear) for this South American taxon. Comparisons of the cranial endocast of L. tessonei with other sauropods indicate that 1) South American rebbachisaurids are more similar to each other than to Nigersaurus, and 2) certain association of traits are present in all known rebbachisaurid cranial endocasts, such as lack of an enlarged dorsal expansion, poorly laterally projected cerebral hemispheres, presence of a small flocculus of the cerebellum, markedly long passage for the facial nerve (CN VII), markedly inclined pituitary, and presence of a passage for the basilar artery communicating the floor of the endocranial cavity and the pituitary fossa. The relatively enlarged olfactory region indicates that smell was an important sense for this group of dinosaurs, suggesting different olfactory capabilities when compared to coeval titanosaurs.
... Later, regional stratigraphic studies interpreted these deposits as an extension of the Periá Formation (Cajú Group) Pedrão et al., 2002;Zalán, 2007). Fossils from the Itapecuru Formation have been identified and inventoried (Santos and Carvalho, 2009) in the Parnaíba Basin, providing the following ages for the surrounding rocks and along the margins of the Itapecuru River: Albian (Campos, 1925;Maury, 1925;Ferreira and Cassab, 1987;Pedrão et al., 1993;Vicalvi et al., 1996;Vicalvi and Carvalho, 2002), middle-lower Albian (Pedrão et al., 1994;Corrêa-Martins and Pedrão, 1998;Pedrão and Corrêa-Martins, 1999;Ferreira et al., 2011), upper Aptian (Ferreira, 2015;Ferreira et al., 2016Ferreira et al., , 2018a and Lower Cretaceous or Aptian-Albian (Ferreira et al., 1991, Ferreira et al., 1992, 1995Carvalho, 1993Carvalho, , 1994Vicalvi et al., 1993;Kischlat and Carvalho, 2000;Carvalho et al., 2003). ...
The thick, predominantly siliciclastic deposits of the Itapecuru Formation cover a large geographical area. Their deposition was controlled by strong tectonism in the rift stage of the Gondwana separation and by the evolution of the Atlantic Ocean, with the Cretaceous section of the Parnaíba Basin being related to the development of the Equatorial Segment. The age assignment for the Itapecuru Formation is based on the chronostratigraphic positioning of its exposed deposits along the Itapecuru River, in the eastern area of the Parnaíba Basin. Due to their high biostratigraphic resolution in both continental and marine sections, palynomorphs were chosen to accurately assess relative age. Palynofloras are mixed and dominated by terrestrial palynomorphs and aquatic plant spores, with rare marine and Paleozoic reworked palynomorphs. Based on species of biostratigraphic value recorded in the palynological assemblages, the Complicatisaccus cearensis Zone was characterized, thus attributing the upper Aptian age to the deposits. The stratigraphic ranges of Elaterosporites protensus, Elaterosporites verrucatus, Elaterosporites klaszi and Elaterosporites spp. small forms, Cavamonocolpites punctatus, Quadricolpites reticulatus and Elaterocolpites castelainii (A and B forms) are here extended, invalidating the definition of the boundary between the Complicatisaccus cearensis and Elateropollenites jardinei zones. These results allowed the correlation of the studied deposits with depositional sequences. The compositional variation and abundance of Afropollis, Araucariacites and elaterate complex in the palynofloras allowed their correlation with three palynofloristic provinces: Afropollis, Lower Cretaceous Dicheiropollis/Afropollis and Albian-Cenomanian Elaterates, suggesting a wet equatorial climate near the paleo equator.
... Da fauna continental terrestre também foram descritos fragmentos de ovos de dinossauros (Vicalvi et al., 1993), dentes de dinossauros carnívoros e ossadas de dinossauro (Ferreira et al., 1991), que ocorrem ao longo das barrancas do rio Itapecuru. O dinossauro foi denominado por Carvalho et al. (2003) como ...
The fossil record of turtles is abundant in Brazilian Cretaceous rocks from the
Araripe (Lower Cretaceous) and Bauru basins (Upper Cretaceous), where the
majority of species described from Brazil were found. In the Parnaíba Basin, the
discovery of chelonian fossils articulated allowed a detailed study on these animals.
We identify two specimens of Araripemys barretoi and the presence of a new
species, which is uncommon in the organization of its neural and costal plates. They
were found in rocks of Albian age. All the studied material are in a well-preserved
conditions. The specimen UFRJ DG 74R is the most complete and contains
articulated bones to the shell. UFRJ DG 37R contains part of the cervical vertebrae,
but it was broken in half during the sampling. UFRJ DG 66R consists of carapace
and plastron. The study enabled the recognition of new specimens belonging to A.
barretoi and the large distribution of this species in the northeast of Brazil. It was also
identified a new chelonian species, the first exclusively from the Parnaíba Basin. The
fossils allow to infer distinct habitats for each species and to associate them with the
local fauna.
... 3-6) and sebecids (Fig. 2), but also by two newcoming lineages at the continent: Crocodyloidea (Charactosuchus and Brasilosuchus) and Gavialoidea (Fig. 7), through five genera of the Gryposuchinae clade (sensu Vélez-Juarbe et al., 2007). There is, however, one record from the Early Cretaceous of Brazil that has been assigned to Crocodyloidea: Maury (1925) assigned, without illustrations, an isolated tooth from the Itapecuru Formation, of the Early Cretaceous (see Carvalho et al., 2003) as "Crocodylus sp.". ...
The fossil crocodylomorph fauna of the Cenozoic of South America is very rich and diverse. Historically, few
publications have been dedicated to providing an overall review of this fauna, with most reviews focusing on
specific areas. However, the fact that many new species, taxonomic reviews and description of new specimens
have been proposed in the last decade makes a comprehensive review of the fossil crocodylomorph fauna of the
South American Cenozoic necessary. The only crocodylomorph lineages to have a fossil record comprising Late
Cretaceous and Cenozoic deposits in South America is the Dyrosauridae. Sebecidae or its predecessors, however,
are very likely to have inhabited the continent during the Cretaceous-Paleogene transition as well; both
Dyrosauridae and Sebecidae are considered here to have survived the Cretaceous-Paleogene extinction while
inhabiting South America. Caimaninae (Alligatoroidea) arrived either in the late Cretaceous or in the early
Paleocene coming from North America. The fossil record of Caimaninae is present, however, only from the
Paleocene. By the Eocene, there are no records of Dyrosauridae in South America; this group was globally extinct
after the Eocene, possibly due to the global cooling that occurred by the end of the epoch. Sebecids and caimanines
solely comprised the crocodylomorph fauna of the continent until the Miocene, where there are the first
records of Gavialoidea (Gryposuchinae) and a possible first dispersion of Crocodyloidea, through the tentative
tomistomines Charactosuchus and Brasilosuchus. Gryposuchinae likely arrived in the continent from Africa or
from Asia during the Oligocene. Charactosuchus and Brasilosuchus may have come from North America where
tomistomines lived from the Oligocene to the Pliocene. Sebecids were extinct after the middle Miocene;
Charactosuchus, Gryposuchinae, Purussaurus, Mourasuchus and durophagous caimanines such as Gnatusuchus
were extinct after the late Miocene. These extinctions are related to changes in the drainage basins caused by
elevation of the Andes mountain range. Only the extant caimanine Caiman, Melanosuchus and Paleosuchus would
survive the Miocene, being enriched by Crocodylus from the Pliocene onwards, which is likely that Crocodylus
arrived in the American continents from Africa. The current fossil record indicates that these four genera
comprise the extant crocodylian fauna of the continent since the Pliocene. Although our knowledge on crocodylomorph
fossil fauna of the South American Cenozoic has increased continuosly, especially in the last decade,
much yet must be done, especially on the taxonomy and phylogeny of Brasilosuchus and Charactosuchus, fieldworks
in Paleogene and Pliocene localities, and the evolution of the specialized Caimaninae morphotypes.
... The depositional environments interpreted for Itapecuru Formation are fluvial, lacustrine, fluvio-deltaic and estuarine (Campbell et al., 1949;Caputo, 1984;Gonçalves and Carvalho, 1996;Rossetti et al., 2001;Carvalho et al., 2003;Rossetti and G oes, 2003;Miranda and Rossetti, 2006;Pessoa, 2007;Ferreira et al., 2016). The studied outcrops show intercalations between paleosols and deposits, with architectural elements external to the river channel, such as floodplain, crevasse splay deposits and paleosols (Menezes, 2018) (Fig. 9). ...
... Up to date, the knowledge of Brazilian dinosaurs is very restricted, with only 10 species reported so far: six theropods, three sauropods and one basal sauropodomorph (Kellner and Campos 2000;Carvalho et al. 2003). Unaysaurus tolentinoi is the eleventh Brazilian dinosaur taxon described, with an almost complete skull. ...
A new early dinosaur, Unaysaurus tolentinoi gen. et sp. nov., from the continental Late Triassic red beds of the Caturrita Formation (Carnian-Norian, c. 225 million years old) of southern Brazil is described. U. tolentinoi is represented by a semi-articulated skeleton comprising an almost complete skull, lower jaw and postcranial elements. It differs from all other dinosaurs by several cranial (e.g. developed laterodorsally oriented process formed by frontal and parietal; deep ventral depression on the basisphenoid) and postcranial (presence of a conspicuous blunt ridge running on the lateral surface of the deltopectoral crest of humerus) characters. Unaysaurus represents the first prosauropod grade dinosaur from Brazil and a preliminary phylogenetic analysis indicates it to be closely related to the European Plateosaurus (Plateosauridae). The relationships of the Prosauropoda , however, are still controversial and more comprehensive studies are needed before a clear picture of the evolution and paleobiogeographic distributions of these dinosaurs can be presented.
... The recognition of the recurrence of these forms and the importance of a clade with a southern signature led Bonaparte (1997) to coin Rebbachisauridae for a family that he already recognised as different from the remaining diplodocoids (Bonaparte 1996). This name was later used by Sereno et al. (1999), Wilson (1999), Pereda Suberbiola et al. (2001Suberbiola et al. ( , 2003, Carvalho et al. (2003) and Harris and Dodson (2004). The formal definition was later given by Upchurch et al. (2004) and subsequently used by Salgado et al. (2004), Gallina and Apesteguía (2005), Wilson (2005) and Apesteguía (2007). ...
Rebbachisauridae are poorly known 'bizarre' sauropods with two nearly complete skeletons collected: Limaysaurus tessonei and Nigersaurus taqueti. Whereas the latter taxon allowed the understanding of their cranial novelties, other species show some peculiarities in the postcranium. L. tessonei, Rebbachisaurus garasbae and a new form (MMCH-Pv-49) from Villa El Chocón, Patagonia, exhibit peculiar pectoral girdles and the loss of the hyposphene-hypantrum accessory articulations in their amphiplathyan dorsal vertebrae. Actually, the postzygapophyses are not only devoid of hyposphenal locks but also additionally show a curved postzygapophyseal eave that allows a sliding over the corresponding structure of the anterior side of the neural arch, a curved concave and elongated platform continuous along both prezygapophyses: the prezygapophyseal shelf. As the 'ball and socket' opisthocoelous centra in macronarians optimised mobility, the 'U-eaves and shelf complex' of rebbachisaurids permitted wider movements between successive vertebrae. While in titanosaurs the increased mobility occurred related to the centrum shape, in rebbachisaurids it is related to a complex system in the neural arch. Furthermore, whereas macronarians show large centra, rebbachisaurids underwent a minimisation of the centrum. These changes in both sauropod lineages probably had an outstanding relevance in the diversity and ecological roles that sauropods experienced in Cretaceous terrestrial ecosystems.
... Despite the considerable number of Lower Cretaceous continental sedimentary deposits in Brazil, body fossil remains of Early Cretaceous dinosaurs have only been formally documented in the AptianeAlbian Araripe and S~ ao Luís-Grajaú basins (Kellner and Campos, 1996; Martill et al., 1996; Kellner, 1999; Medeiros and Schultz, 2002; Sues et al., 2002; Carvalho et al., 2003; Naish et al., 2004; Medeiros, 2006; Castro et al., 2007; Bittencourt and Langer, 2011; Kellner et al, 2011; Lindoso et al., 2012; Faria et al., 2015). Curiously though, dinosaur footprints from the Lower Cretaceous of Brazil are pervasive (e.g. ...
Here we describe a new record of a sauropod dinosaur from the Lower Cretaceous (Hauterivian-Barremian) Rio Piranhas Formation, Sousa Basin, NE Brazil. Dinosaur fossil bones from this deposit were
unknown until now. Thus, the discovery of a sauropod fibula from this locality is highly significant. Our
discovery represents an indeterminate titanosaur and the earliest stratigraphic occurrence of this group
in central Gondwana. When compared to chronocorrelate titanosaur trackmakers of this geological unit,
this fossil specimen appears substantially smaller. Histological analysis of the fibula suggests that this is a
relatively young individual (approximately 40-50% adult body size) that had passed its most rapid phase
of early juvenile growth, but had not yet attained somatic maturity. Thus, the fibula recovered is from a
young individual rather than from a small-bodied adult titanosaur.
... The group includes early splits (e.g., Phuwiangosaurus) and the Lithostrotia lineage, also including early splits and clades like Nemegtosauridae, Saltasaurinae, Opisthocoelicaudinae, and Aeolosaurini (Apesteguia, 2004; Wilson & Upchurch, 2003; Upchurch, Barrett & Dodson, 2004; Santucci & Arruda-Campos, 2011). Sauropods are currently represented in Brazil by ten formally proposed Cretaceous taxa (Fig. 1), all within the Titanosauria clade, except for the diplodocoid Amazonsaurus maranhensis (Carvalho, Avilla & Salgado, 2003). Described by Kellner et al. (2006) from deposits of the Adamantina Formation, in Minas Gerais, Maxakalisaurus topai corresponds to one of those titanosaurs, and seems closely related to the Aelosaurini group (Santucci & Arruda-Campos, 2011). ...
Sauropod dinosaurs compose a diversified, well known, and worldwide distributed clade, with a stereotyped body plan: deep trunk, elongated neck and tail, columnar limbs and very small skull. In Brazil, the group is represented by ten formally described Cretaceous species, mostly titanosaurs. This is the case of
Maxakalisaurus topai
, known based on an incomplete and disarticulated skeleton, unearthed from deposits of the Adamantina Formation in Minas Gerais. Here, we report a partial right dentary, including five isolated teeth, collected from the same site as the type-series of
M. topai
and tentatively referred to that taxon. The bone is gently curved medially, the functional teeth are set on an anterolingual position, and two replacement teeth are seen per alveoli. New morphological data gathered from that specimen was employed to conduct a comprehensive phylogenetic analysis of Titanosauria (with 42 taxa and 253 characters), based on previous studies. The Aeolosaurini clade was recovered, with
Gondwanatitan
and
Aelosaurus
as sister taxa, and
Maxakalisaurus
,
Panamericansaurus
, and
Rinconsaurus
forming a basal polytomy.
... Evidence of air sacs in sauropods is supported by presence of pneumatic fossae, foramina, and laminae in vertebrae, ribs, and some appendicular elements (Janensch, 1947;Britt, 1993;Wilson, 1999;Carvalho et al., 2003;Wedel, 2005;Schwarz et al. 2007;Wilson and Upchurch, 2009;Cerda et al., 2012;Fanti et al., 2013). Sereno et al. (2008) hypothesized that the cervical air sac system pneumatized the entire presacral column in non-avian dinosaurs, as evidenced by the pneumatization pattern found in most theropod dinosaurs. ...
Well-preserved, articulated juvenile sauropod dinosaur material is very rare, hindering attempts to understand ontogenetic changes within the clade. Here, we describe an exceptionally preserved partial skeleton of a Barosaurus from the Morrison Formation of Dinosaur National Monument, Utah, U.S.A., that is only about one-third adult size. This small size and the lack of fusion of neurocentral and costovertebral sutures indicate that the individual is a juvenile. Apomorphy-based taxonomic identification of the specimen combined with the excellent preservation of its vertebral column allows documentation of both serial and ontogenetic morphological changes in Barosaurus. Each vertebra underwent substantial morphological change in the relative height of the neural spine and location of the zygapophyseal and diapophyseal articular facets during ontogeny but not in the degree of bifurcation of the neural spines. Pneumaticity in the dorsal vertebrae varies serially: large pneumatic fossae punctuate the centra of dorsal vertebrae 1–4 and 8–9, whereas these spaces are occupied by shallow depressions in dorsal vertebrae 5–7. This represents the first known caudal dorsal pneumatic hiatus in a sauropod dinosaur, which suggests that separate air sacs pneumatized the anterior and posterior regions of the dorsal vertebral column, congruent with the pattern observed in non-avian and avian theropod dinosaurs and the presence of an avian-style lung in sauropods. Citation for this article: Melstrom, K. M., M. D. D'Emic, D. Chure, and J. A. Wilson. 2016. A juvenile sauropod dinosaur from the Late Jurassic of Utah, U.S.A., presents further evidence of an avian style air sac system. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1111898.
... A large number of macrofossil and microfossil taxa from the Itapecuru Formation has been documented (Carvalho, 1994;Carvalho et al., 2003;Santos and Carvalho, 2004). Among these microfossils, there are palynomorphs, which are organic remains recovered in palynological preparations, such as spores (bryophytes and pteridophytes), pollen grains (gymnosperms and angiosperms), dinoflagellates, scolecodonts, acritarchs, colonies of chlorophytic algae and prasinophycean phycomata. ...
... Iliac internal chambers are reported in Amazonsaurus [73] and Tataouinea, and may represent a synapomorphy of Rebbachisauridae. An internal pneumatisation of the ischium is present in both Rebbachisaurus [40] and Tataouinea, but only the latter shows a pneumatic foramen perforating the lateral surface of the iliac peduncle, a feature absent in both Demandasaurus and Rebbachisaurus [40,74] and thus autapomorphic for the Tunisian taxon [1]. ...
The rebbachisaurid sauropod Tataouinea hannibalis represents the first articulated dinosaur skeleton from Tunisia and one of the best preserved in northern Africa. The type specimen was collected from the lower Albian, fluvio-estuarine deposits of the Ain el Guettar Formation (southern Tunisia). We present detailed analyses on the sedimentology and facies distribution at the main quarry and a revision of the vertebrate fauna associated with the skeleton. Data provide information on a complex ecosystem dominated by crocodilian and other brackish water taxa. Taphonomic interpretations indicate a multi-event, pre-burial history with a combination of rapid segregation in high sediment supply conditions and partial subaerial exposure of the carcass. After the collection in 2011 of the articulated sacrum and proximalmost caudal vertebrae, all showing a complex pattern of pneumatization, newly discovered material of the type specimen allows a detailed osteological description of Tataouinea. The sacrum, the complete and articulated caudal vertebrae 1–17, both ilia and ischia display asymmetrical pneumatization, with the left side of vertebrae and the left ischium showing a more extensive invasion by pneumatic features than their right counterparts. A pneumatic hiatus is present in caudal centra 7 to 13, whereas caudal centra 14–16 are pneumatised by shallow fossae. Bayesian inference analyses integrating morphological, stratigraphic and paleogeographic data support a flagellicaudatan-rebbachisaurid divergence at about 163 Ma and a South American ancestral range for rebbachisaurids. Results presented here suggest an exclusively South American Limaysaurinae and a more widely distributed Rebbachisaurinae lineage, the latter including the South American taxon Katepensaurus and a clade including African and European taxa, with Tataouinea as sister taxon of Rebbachisaurus. This scenario would indicate that South America was not affected by the end-Jurassic extinction of diplodocoids, and was most likely the centre of the rapid radiation of rebbachisaurids to Africa and Europe between 135 and 130 Ma.
Paleosols are an under-utilized tool for paleoenvironmental and paleoclimatic reconstruction in Brazilian intracontinental basins. The Itapecuru Formation, from the Lower Cretaceous of the Parnaíba Basin, consists of a 600-m-thick succession of interbedded very fine-to-fine-grained sandstone, mudstone, and paleosols containing rich fossil assemblages. This paper provides a detailed description of the macro and microscopic pedogenic features of a hydromorphic paleosol profile whithin the Itapecuru Formation. Analyses of clay mineralogy and whole-rock geochemistry in the hydromorphic paleosols at the Prata locality are used to infer pedogenic processes, paleoclimate, paleohumidity and paleovegetation. Estimates of paleoprecipitation and paleotemperature using climofunctions, chemical index of alteration without potassium, and paleosol weathering index proxies (PWIs) show values ranging from 810 to 1042 mm/yr (SE = ±78.1 mm/yr) and 10.9 to 11.8 °C (SE = ±0.23 °C), respectively. Climofunction values (MAP and MAT), paleohumidity, Kӧppen aridity index, and pedogenic clay mineral content suggest a humid paleoclimate during soil-forming and weathering processes. Based on these climate data and previously published paleogeographic and palynological studies, the Cretaceous (Albian) Prata pedotype was formed within the equatorial humid belt with vegetation of wet tropical forests.
The Early Jurassic and Cretaceous deposits of India are known for their diverse sauropod fauna, while little is known from the Middle and Late Jurassic. Here we report the first ever remains of a dicraeosaurid sauropod from India, Tharosaurus indicus gen. et sp. nov., from the Middle Jurassic (early–middle Bathonian) strata of Jaisalmer Basin, western India. Known from elements of the axial skeleton, the new taxon is phylogenetically among the earlier-diverging dicraeosaurids,
and its stratigraphic age makes it the earliest known diplodocoid globally. Palaeobiogeographic considerations of Tharosaurus, seen in conjunction with the other Indian Jurassic sauropods, suggest that the new Indian taxon is a relic of a lineage that originated in India and underwent rapid dispersal across the rest of Pangaea. Here we emphasize the importance of Gondwanan India in tracing the
origin and early evolutionary history of neosauropod dinosaurs.
It is investigated the paleoecology of Araripemys barretoi Price, 1973 a pelomedusoid turtle from the Lower Cretaceous (Aptian) of Araripe and Parnaíba basins, Brazil. The analysis of forelimbs proportions allowed to interpret Araripemys barretoi as a turtle with a specialized morphology to live in large water bodies, as an agile swimmer. Several postcranial anatomical features suggest that Araripemys barretoi was able to live in aquatic environments of distinct magnitudes. This species was abundant throughout the Aptian in the Araripe and Parnaíba basins, where an epicontinental sea once existed, during the first marine ingressions related to the Equatorial Atlantic opening.
Most taphonomy studies of South American sauropodomorphs have addressed extrinsic factors such as sedimentary environments, bone dispersal, and mineralogical processes that occurred during fossil diagenesis. These studies provide important data on the taphonomic modes which are associated with bone accumulations in different paleoenvironmental contexts. However, these analyses have generally not considered intrinsic factors like the shape, size, and structural integrity of the skeletal elements, variables that can produce some taphonomic bias. Sauropodomorphs include dinosaurs of highly varied sizes, ranging from small (less than 8 m long) to remarkably giant forms (around 30 m long). In the largest sauropods, such as the huge titanosaurs, very incomplete skeletons are commonly found and most notably skull and articulated pedes rarely are preserved. We focus here on some intrinsic anatomical factors as they relate to articulation in some key parts of the skeletons. Further, this study suggests that the preservation of fragile portions of sauropodomorph skeletons was possible only under specific combinations of sedimentological and biological processes.
The titanosaurian sauropod dinosaur Diamantinasaurus matildae is represented by two individuals from the Cenomanian-lower Turonian 'upper' Winton Formation of central Queensland, northeastern Australia. The type specimen has been described in detail, whereas the referred specimen, which includes several elements not present in the type series (partial skull, atlas, axis and postaxial cervical vertebrae), has only been described briefly. Herein, we provide a comprehensive description of this referred specimen, including a thorough assessment of the external and internal anatomy of the braincase, and identify several new autapomorphies of D. matildae. Via an expanded data matrix consisting of 125 taxa scored for 552 characters, we recover a close, well-supported relationship between Diamantinasaurus and its contemporary, Savannasaurus elliottorum. Unlike previous iterations of this data matrix, under a parsimony framework we consistently recover Diamantinasaurus and Savannasaurus as early-diverging members of Titanosauria using both equal weighting and extended implied weighting, with the overall topology largely consistent between analyses. We erect a new clade, named Diamantinasauria herein, that also includes the contemporaneous Sarmientosaurus musacchioi from southern Argentina, which shares several cranial features with the referred Diamantinasaurus specimen. Thus, Diamantinasauria is represented in the mid-Cretaceous of both South America and Australia, supporting the hypothesis that some titanosaurians, in addition to megaraptoran theropods and possibly some ornithopods, were able to disperse between these two continents via Antarctica. Conversely, there is no evidence for rebbachisaurids in Australia, which might indicate that they were unable to expand into high latitudes before their extinction in the Cenomanian-Turonian. Likewise, there is no evidence for titanosaurs with procoelous caudal vertebrae in the mid-Cretaceous Australian record, despite scarce but compelling evidence for their presence in both Antarctica and New Zealand during the Campanian-Maastrichtian. These later titanosaurs presumably dispersed into these landmasses from South America before the Campanian (~85 Mya), when seafloor spreading between Zealandia and Australia commenced. Although Australian mid-Cretaceous dinosaur faunas appear to be cosmopolitan at higher taxonomic levels, closer affinities with South America at finer scales are becoming better supported for sauropods, theropods and ornithopods.
The Late Jurassic Tendaguru Formation of Tanzania, southeastern Africa, records a rich sauropod fauna, including the diplodocoids Dicraeosaurus and Tornieria, and the brachiosaurid titanosauriform Giraffatitan. However, the taxonomic affinities of other sympatric sauropod taxa are poorly understood. Here, we critically reassess and redescribe these problematic taxa, and present the largest phylogenetic analysis for sauropods (117 taxa scored for 542 characters) to explore their placement in Eusauropoda. Janenschia robusta has played a prominent role in discussions of titanosaur origins, with various authors referring at least some remains to Titanosauria, a clade otherwise known only from the Cretaceous. Redescription of the holotype of Janenschia, and all referable remains, supports its validity and placement as a nonneosauropod eusauropod. It forms a clade with Haestasaurus from the earliest Cretaceous of the UK, and the Middle/Late Jurassic Chinese sauropod Bellusaurus. Phylogenetic analysis and CT scans of the internal pneumatic tissue structure of Australodocus bohetii tentatively support a non-titanosaurian somphospondylan identification, making it the only known pre-Cretaceous representative of that clade. New information on the internal pneumatic tissue structure of the dorsal vertebrae of the enigmatic Tendaguria tanzaniensis, coupled with a full redescription, results in its novel placement as a turiasaur. Tendaguria is the sister taxon of Moabosaurus, from the Early Cretaceous of North America, and is the first turiasaur recognized from Gondwana. A previously referred caudal sequence cannot be assigned to Janenschia and displays several features that indicate a close relationship with Middle–Late Jurassic East Asian mamenchisaurids. It can be diagnosed by six autapomorphies, so we erect the new taxon Wamweracaudia keranjei gen. et sp. nov. The presence of a mamenchisaurid in the Late Jurassic of southern Gondwana indicates an earlier and more widespread diversification of this clade than previously realized, prior to the geographic isolation of East Asia. Our revised phylogenetic dataset sheds light on the evolutionary history of Eusauropoda, including supporting a basal diplodocoid placement for Haplocanthosaurus, and elucidating the interrelationships of rebbachisaurids. The Tendaguru Formation shares representatives of nearly all sauropod lineages with Middle Jurassic–earliest Cretaceous global faunas, but displays a greater range of diversity than any of those faunas considered individually. Biogeographic analysis indicates that the Tendaguru sauropod fauna was assembled as a result of three main phenomena during the late Early and/or Middle Jurassic: (1) invasions from Euramerica (brachiosaurids, turiasaurs); (2) endemism in west Gondwana (dicraeosaurids, diplodocids); and (3) regional extinctions that restricted the ranges of once widespread groups (mamenchisaurids, the Janenschia lineage). Multiple dispersals across the Central Gondwanan Desert are required to explain the distributions of Jurassic sauropods, suggesting that this geographic feature was at most a filter barrier that became easier to cross during the late Middle Jurassic.
Extensive and well-preserved tracksites in the coastally exposed Lower Cretaceous (Valanginian–Barremian) Broome Sandstone of the Dampier Peninsula provide almost the entire fossil record of dinosaurs from the western half of the Australian continent. Tracks near the town of Broome were described in the late 1960s as Megalosauropus broomensis and attributed to a medium-sized theropod trackmaker. Brief reports in the early 1990s suggested the occurrence of at least another nine types of tracks, referable to theropod, sauropod, ornithopod, and thyreophoran trackmakers, at scattered tracksites spread over more than 80 km of coastline north of Broome, potentially representing one of the world's most diverse dinosaurian ichnofaunas. More recently, it has been proposed that this number could be as high as 16 and that the sites are spread over more than 200 km. However, the only substantial research that has been published on these more recent discoveries is a preliminary study of the sauropod tracks and an account of the ways in which the heavy passage of sauropod trackmakers may have shaped the Dampier Peninsula's Early Cretaceous landscape. With the other types of dinosaurian tracks in the Broome Sandstone remaining undescribed, and the full extent and nature of the Dampier Peninsula's dinosaurian tracksites yet to be adequately addressed, the overall scientific significance of the ichnofauna has remained enigmatic.
At the request of the area's Goolarabooloo Traditional Custodians, 400+ hours of ichnological survey work was undertaken from 2011 to 2016 on the 25 km stretch of coastline in the Yanijarri–Lurujarri section of the Dampier Peninsula, inclusive of the coastline at Walmadany (James Price Point). Forty-eight discrete dinosaurian tracksites were identified in this area, and thousands of tracks were examined and measured in situ and using three-dimensional photogrammetry. Tracksites were concentrated in three main areas along the coast: Yanijarri in the north, Walmadany in the middle, and Kardilakan–Jajal Buru in the south. Lithofacies analysis revealed 16 repeated facies types that occurred in three distinctive lithofacies associations, indicative of an environmental transgression between the distal fluvial to deltaic portions of a large braid plain, with migrating sand bodies and periodic sheet floods. The main dinosaurian track-bearing horizons seem to have been generated between periodic sheet floods that blanketed the preexisting sand bodies within the braid plain portion of a tidally influenced delta, with much of the original, gently undulating topography now preserved over large expanses of the present day intertidal reef system. Of the tracks examined, 150 could be identified and are assignable to a least eleven and possibly as many as 21 different track types: five different types of theropod tracks, at least six types of sauropod tracks, four types of ornithopod tracks, and six types of thyreophoran tracks. Eleven of these track types can formally be assigned or compared to existing or new ichnotaxa, whereas the remaining ten represent morphotypes that, although distinct, are currently too poorly represented to confidently assign to existing or new ichnotaxa. Among the ichnotaxa that we have recognized, only two (Megalosauropus broomensis and Wintonopus latomorum) belong to existing ichnotaxa, and two compare to existing ichnotaxa but display a suite of morphological features suggesting that they may be distinct in their own right and are therefore placed in open nomenclature. Six of the ichnotaxa that we have identified are new: one theropod ichnotaxon, Yangtzepus clarkei, ichnosp. nov.; one sauropod ichnotaxon, Oobardjidama foulkesi, ichnogen. et ichnosp. nov.; two ornithopod ichnotaxa, Wintonopus middletonae, ichnosp. nov., and Walmadanyichnus hunteri, ichnogen. et ichnosp. nov.; and two thyreophoran ichnotaxa, Garbina roeorum, ichnogen. et ichnosp. nov., and Luluichnus mueckei, ichnogen. et ichnosp. nov. The level of diversity of the main track types is comparable across areas where tracksites are concentrated: Kardilakan–Jajal Buru (12), Walmadany (11), and Yanijarri (10).
The overall diversity of the dinosaurian ichnofauna of the Broome Sandstone in the Yanijarri–Lurujarri section of the Dampier Peninsula is unparalleled in Australia, and even globally. In addition to being the primary record of non-avian dinosaurs in the western half of Australia, this ichnofauna provides our only detailed glimpse of Australia's dinosaurian fauna during the first half of the Early Cretaceous. It indicates that the general composition of Australia's mid-Cretaceous dinosaurian fauna was already in place by the Valanginian–Barremian. Both sauropods and ornithopods were diverse and abundant, and thyreophorans were the only type of quadrupedal ornithischians. Important aspects of the fauna that are not seen in the Australian mid-Cretaceous body fossil record are the presence of stegosaurians, an overall higher diversity of thyreophorans and theropods, and the presence of large-bodied hadrosauroid-like ornithopods and very large-bodied sauropods. In many respects, these differences suggest a holdover from the Late Jurassic, when the majority of dinosaurian clades had a more cosmopolitan distribution prior to the fragmentation of Pangea. Although the record for the Lower Cretaceous of Gondwana is sparse, a similar mix of taxa occurs in the Barremian–lower Aptian La Amarga Formation of Argentina and the Berriasian–Hauterivian Kirkwood Formation of South Africa. The persistence of this fauna across the Jurassic-Cretaceous boundary in South America, Africa, and Australia might be characteristic of Gondwanan dinosaurian faunas more broadly. It suggests that the extinction event that affected Laurasian dinosaurian faunas across the Jurassic-Cretaceous boundary may not have been as extreme in Gondwana, and this difference may have foreshadowed the onset of Laurasian-Eurogondwanan provincialism. The disappearance of stegosaurians and the apparent drop in diversity of theropods by the mid-Cretaceous suggests that, similar to South America, Australia passed through a period of faunal turnover between the Valanginian and Aptian. -------- In: Society of Vertebrate Paleontology Memoir (Journal of Vertebrate Paleontology Vol. 36, supplement to 6, November 2016).
Candidodon itapecuruense Carvalho & Campos, 1988 was described from skeletal remains from
Itapecuru Formation, Parnaíba Basin, Brazil, but only cranial and tooth elements were originally
analysed. In this study we describe the appendicular and axial skeleton of C. itapecuruense and its
taphonomy using non-invasive methods. In this research were used stereophotomicrography and
micro-ct scans for description of the skeleton and taphonomic data retrieving. All described materials
are strongly fragmented due to previous mechanical treatment. Micro-ct scans suggests that the
material was buried articulated with no or minor transport under influence of tractive depositional
processes. This, combined with faciological data, indicates an ancient floodplain as its
paleodepositional environment. Among the materials within tomographed sediments there are pelvic
and autopodium elements still articulated and mandible fragments. The axial skeleton remains are
composed of five vertebra, three of them still articulated. Their centra are anficoleous, with pre-
zygapophisis anteriorly and laterally projected, plain, lightly medially oriented articular surfaces. The
neural spines are plain and well developed dorsally while the transverse process is poorly developed
and weakly laterally projected. Among the appendicular remains there are: coracoid, humerus,
radius, ulna, femur, fibula, tibia and some elements from the autopodium. Major muscular attachment
structures are proximally positioned. The bones are thick, however, elongated. The post-cranial
materials of Candidodon suggests that it was a small crocodyliform with upright posture, agile
movements and diversified dietary habits.
The Galve fossil sites (province of Teruel, Spain) have provided many Mesozoic vertebrate remains. Among these are isolated sauropod dinosaur bones, including one taxon reported only from this locality, Aragosaurus ischiaticus. Here, a new species is named from the Tithonian deposits of the Villar del Arzobispo Formation, of Galve (Teruel province, Spain), Galveosaurus herreroi gen. et sp. nov. It is represented by two humeri, one sternal plate, one ischium, one scapula, one cervical vertebra, one caudal dorsal vertebra, five caudal vertebrae, one Y-shaped chevron and some fragments of ribs. This new species is an eusauropod dinosaur that shows primitive features such as a slightly curved ischium with an unexpanded distal end, amphicoelous vertebrae, neural spine not bifid and an unforked chevron. It appears to be closer to cetiosaurid genera such as Barapasaurus or Cetiosaurus. This new basal sauropod lived at the same time as the eusauropod Lourinhasaurus alenquerensis from Portugal. These are both relict genera that survived in the Iberian Peninsula when more derived neosauropods, such as Losillasaurus or Dinheirosaurus, had taken over other parts of Iberia.
A new titanosaur dinosaur, Brasilotitan nemophagus gen. et sp. nov., is described from the Adamantina Formation (Turonian-Santonian, Bauru Basin). The specimen consists of a dentary, cervical and sacral vertebrae, one ungual and remains of the pelvic region, that were collected near Presidente Prudente city, Sdo Paulo State. It shows a mandible with an 'L' shaped morphology, with the symphyseal region of the dentary slightly twisted medially, a feature never recorded before in a titanosaur. Brasilotitan nemophagus can be further separated from other members of this clade by: (1) the dorsal portion of the dentary symphyseal contact is broader anteroposteriorly than the ventral part; (2) the ventral portion of the cervical centrum is arched dorsally; (3) the presence of an anteriorly directed accessory prezygapophyseal articulation surface on the cervical vertebrae; (4) the intraprezygapophyseal laminae of the cervical vertebrae are 'V' shaped in dorsal view; and other features. Although the phylogenetic position of Brasilotitan nemophagus is difficult to establish, the new species is neither a basal nor a derived member of the Titanosauria and, based on the lower jaw morphology, appears to be closely related to Antarctosaurus wichmannianus and Bonitasaura salgadoi. This discovery enriches the titanosaur diversity of Brazil and further provides new anatomical information on the lower jaws of those herbivorous dinosaurs.
In northeastern Brazil the evolution of some early Cretaceous basins is found to have occurred during the transcurrents displacements of the east-west trending Patos-Paraíba and northeast-southeast trending Portalegre fault system, at the beginning of the South America - Africa drifting. In this study the present geological knowledge of some of the basins, namely, those in western Paraíba stale - the Pombal, Sousa, Uiraúna. Brejo das Freiras and Vertentes basins - is discussed. The sediments in these areas are micro and macroclastic material derived from fluvial and lacustrine sources; whereas the paleobiological evidence consists of invertebrates (conchostraccans and ostracods), vertebrates (fish scales and bones), pollens and plant remains. The invertebrate ichnofossils and the dinossaur trackways are also frequent at the sedimentary rocks of this area.
Lower Cretaceous fossils from central Niger document the succession of sauropod dinosaurs on Africa as it drifted into geographic
isolation. A new broad-toothed genus of Neocomian age (∼135 million years ago) shows few of the specializations of other Cretaceous
sauropods. A new small-bodied sauropod of Aptian-Albian age (∼110 million years ago), in contrast, reveals the highly modified
cranial form of rebbachisaurid diplodocoids. Rates of skeletal change in sauropods and other major groups of dinosaurs are
estimated quantitatively and shown to be highly variable.
PALEOGEOGRAPHICAL AND BIOCHRONOLOGICAL DISTRIBUTIONS OF THE BAURU GROUP TITANOSAURIDS (SÁ URISCHÍA, SÁ UROPODA), UPPER CRETACEOUS OF SOUTHEASTERN BRAZIL The Titanosauridae (Saurischia, Sauropoda) is a very common herbivorous dinosaur family in the Upper Cretaceous deposits from South America. In Brazil, titanosaurids occurrences are more usual to the Bauru Group, and they are widely distributed in this unit, comprising especially Álvares Machado, Presidente Prudente, São José do Rio Preto, Monte Alto cities in the State of São Paulo, and Uberaba in Minas Gerais. Morphological analysis of the available specimens revealed two main paleogeographic associations. The first, including occurrences near São José do Rio Preto, Ibirá, Uchôa and Cândido Rodrigues (São Paulo State), and the second Uberaba (Minas Gerais State). The presence of the genus Aeolosaurus in the Adamantina Formation from Álvares Machado and Monte Alto (São Paulo State) and in the Serra da Galga Member of the Marília Formation in Uberaba (Minas Gerais State) indicates a Late Campanian/Early Maastrichtian age for this portion of the Bauru Group. This same clade is found, in the Neuquén Basin (Argentina) suggesting possible associations between Brazilian and Argentine sauropods, at least during the Late Cretaceous. RESUMO A Família Titanosauridae (Saurischia, Sauropoda) constitui um grupo de dinossauros herbívoros muito comum em depósitos do Cretáceo Superior sul-americano. No Brasil são mais abundantes, até o momento, nos sedimentos do Grupo Bauru. Estas ocorrências brasileiras abrangem praticamente todos os domínios desta unidade, como as regiões de Álvares Machado, Presidente Prudente, São José do Rio Preto, Monte Alto, no Estado de São Paulo (SP) e Uberaba (Distrito de Peirópolis), no Estado de Minas Gerais (MG). A análise dos diferentes padrões morfológicos destes materiais revelou que há dois agrupamentos paleogeográficos principais. Um destes se refere às regiões de São José do Rio Preto, Ibirá, Uchôa e Cândido Rodrigues (SP), e o outro à região de Uberaba (MG). O registro do gênero Aeolosaurus no Brasil, presente na Formação Adamantina em Monte Alto e Álvares Machado -SP, e na base do Mem-bro Serra da Galga (Formação Marília) em Uberaba -MG, configura-se em um importante indicador biocronológico, por atestar idade neocampaniana/eomaastrichtiana para as citadas porções destas unidades. Este mesmo gênero ocorre na Bacia de Neuquén (Argentina), indi-cando alguma associação entre saurópodos brasileiros e argentinos, pelo menos durante o final do Cretáceo.
Most recent studies of dinosaur phylogeny have concentrated on theropods and ornithischians. As a result, the evolutionary relationships of sauropod dinosaurs are poorly understood. In this paper previous studies of sauropod phylogeny are reviewed and contrasted with the results of a recent cladistic analysis. This analysis forms the basis for a reconstruction of sauropod phylogeny. Sauropods diverged from other dinosaurs at some time in the Upper Triassic, but a large part of their early history is totally unknown. Vulcanodon is currently the most primitive sauropod. Many, but perhaps not all, of the Jurassic Chinese sauropods form a monophyletic radiation (the Euhelopodidae) which may reflect the geographic isolation of China during the Lower Jurassic. Members of the Euhelopodidae, such as Mamenchisaurus, are not considered to be closely related to the Diplodocidae. `Forked' chevrons, which have played such an important role in previous studies of sauropod phylogeny, are here considered to have evolved twice within the Sauropoda. This convergence may reflect a correlation between chevron shape and the use of the tail as a weapon within these two sauropod families. The `Neosauropoda' (sister group to the Euhelopodidae) contains the Brachiosauridae, Camara-sauridae and the new superfamilies Titanosauroidea and Diplodocoidea. The Cetiosauridae (here defined in a rather restricted sense) is also provisionally included within the Neosauropoda, but may be removed in future studies. The enigmatic Upper Cretaceous sauropod, Opisthocoelicaudia, is thought to be the sister taxon to the Titanosauridae and not a camarasaurid as previously suggested. The Diplodocoidea contains two well established families, the Dicraeosauridae and Diplodocidae, and the new family Nemegtosauridae. Finally, an overview of sauropod phylogeny is compared with recently published palaeogeographic reconstructions. There are many difficulties associated with the analysis of sauropod biogeographic distribution. Nevertheless, some aspects of sauropod phylogeny may be linked to the break-up of Laurasia and Gondwanaland during the Jurassic and Cretaceous.
Resumen Se ha sugerido una conexión entre Laurasia y Gondwana a lo largo del Cretácico inferior para explicar la presencia de taxones comunes en ambos supercontinentes. Sin embargo la asociación conocida de dinosaurios del Neocomiense de la Península Ibérica y de Gondwana se puede explicar bien como resultado del endemismo y extinciones regionales. Los grupos representados en ambos supercontinentes tienen su origen en el Jurásico Superior, y por tanto con anterioridad a la ruptura de la Pangea. La consecuencia es que se carecen de pruebas faunísticas de la supuesta conexión entre los dos supercontinentes durante el Neocomiense. Por otra parte, algunos taxones presentes en el Hauteriviense-Barremiense de Europa se registran en Gondwana a partir del Aptiense. Sin obviar los problemas relacionados con la falta de registro, cabe la posibilidad que se estableciera una conexión entre Gondwana y Laurasia al final del Barremiense o en el Aptiense, de la cual carecemos de pruebas geológicas. Abstract The similarity between taxons from Laurasia and Gondwana suggest that the two supercontinents may have been connected throughout the Lower Cretaceous. However, the known assemblage of dinosaurs in the Iberian Peninsula and Gondwana during the Neocomian can be explained as a result of endemism and regional extinction. The groups from both supercontinents originated in the Upper Jurassic and thus, before the break-up of Pangea. As a result, we lack faunal proof on the connection between the two supercontinents during the Neocomian. On the other hand, some taxons present in the Hauterivian-Barremian in Europe have been found in Gondwana, beginning in the Aptian. Despite the problems related with the lack of a proper record, we also lack geological proof of a connection between Gondwana and Laurasia at the end of the Barremian or during the Aptian.
Studies modern tracks at Lake Manyara, to document the environmental and taphonomic controls on track preservation. This closed basin, saline lake closely resembles the depositional setting of many ancient track-bearing strata. It is shown that preburial track survivorship can be modelled as the interaction between three variables: 1) strain susceptibility of a substrate prior to track formation; 2) track loading stress; and 3) secondary reworking rate. -from Authors
The vertebrae of sauropods are characterized by numerous bony struts that connect the costovertebral and intervertebral articulations, centrum, and neural spine of the presacral, sacral, and anterior caudal vertebrae. A nomenclature for sauropod vertebral laminae is proposed that: 1) utilizes the morphological landmarks connected by the laminae (rather than their spatial orientation); and 2) provides the same name for serial homologues. This landmark-based nomenclature for vertebral laminae, which establishes the first criterion of homology (similarity), is the first step towards interpreting their phylogenetic significance.Nineteen different neural arch laminae are identified in sauropods, although all are never present in a single vertebra. Vertebral laminae can be divided into four regional categories, with each distinct lamina abbreviated with a simple four-letter acronym: diapophyseal laminae; parapophyseal laminae; zygapophyseal laminae; and spinal laminae.The distribution of neural arch laminae in presacral, sacral, and caudal vertebrae is evaluated to assess homology in sauropods and other saurischians. Five diapophyseal laminae and six zygapophyseal laminae characterize saurischian dinosaurs. Parapophyseal laminae and spinodiapophyseal laminae are unique to a subgroup of sauropods that includes Barapasaurus, Omeisaurus, and Neosauropoda. The presence of diapophyseal laminae in caudal vertebrae characterizes diplodocids.Vertebral laminae probably partitioned pneumatic diverticuli on the neural arch and provided structural support for the axial column. Their basic architecture evolved in saurischians prior to the Late Triassic (Carnian), 25 million years before the first known sauropod.
Dinosaur track deposits of the Upper Cretaceous Jindong Formation, Korea, were examined from a sedimentological viewpoint to interpret their palaeoenvironments and conditions of preservation. The general depositional environment of the Jindong Formation was lake-margin to shallow lacustrine. Lake-margin deposits comprise most of it but the stable isotope values of the carbonates suggest an open lake. There are two types of dinosaur track beds. One is a discrete trackway deposit and the other is a dinoturbated deposit. All of the dinosaur trackways in the formation are preserved in interlaminated fine-grained sandstone to siltstone-mudstone deposits, which were deposited on a dry mudflat at the lake margin by sheetfloods and then underwent calcareous pedogenesis. The dinoturbated deposit was originally calcareous silty mud, reflecting deposition in a shallow lake of low energy. It was also modified later by calcareous pedogenesis. The trampling traces of dinosaurs in the Jindong Formation are recognized both on bedding surfaces and in sections. In places dinosaur tracks occur as ‘overtracks’ which are preserved in layers above the true tracks. The Jindong dinosaur track deposits are usually associated with pedogenic calcretes, which indicates that the climate at the time was seasonal and arid. Consequently, it is interpreted that the extensive and frequent preservation of dinosaur tracks in the Jindong Formation is the result of repeated deposition by sheetfloods on a mudflat associated with a perennial lake, which was utilized by dinosaurs as a persistent water source during drought, and subsequent development of calcareous pedogenesis in an arid climate.
Sauropoda is among the most diverse and widespread dinosaur lineages, having attained a near-global distribution by the Middle Jurassic that was built on throughout the Cretaceous. These gigantic herbivores are characterized by numerous skeletal specializations that accrued over a 140 million-year history. This fascinating evolutionary history has fuelled interest for more than a century, yet aspects of sauropod interrelationships remain unresolved. This paper presents a lower-level phylogenetic analysis of Sauropoda in two parts. First, the two most comprehensive analyses of Sauropoda are critiqued to identify points of agreement and difference and to create a core of character data for subsequent analyses. Second, a generic-level phylogenetic analysis of 234 characters in 27 sauropod taxa is presented that identifies well supported nodes as well as areas of poorer resolution. The analysis resolves six sauropod outgroups to Neosauropoda, which comprises the large-nostrilled clade Macronaria and the peg-toothed clade Diplodocoidea. Diplodocoidea includes Rebbachisauridae, Dicraeosauridae, and Diplodocidae, whose monophyly and interrelationships are supported largely by cranial and vertebral synapomorphies. In contrast, the arrangement of macronarians, particularly those of titanosaurs, are based on a preponderance of appendicular synapomorphies. The purported Chinese clade 'Euhelopodidae' is shown to comprise a polyphyletic array of basal sauropods and neosauropods. The synapomorphies supporting this topology allow more specific determination for the more than 50 fragmentary sauropod taxa not included in this analysis. Their distribution and phylogenetic affinities underscore the diversity of Titanosauria and the paucity of Late Triassic and Early Jurassic genera. The diversification of Titanosauria during the Cretaceous and origin of the sauropod body plan during the Late Triassic remain frontiers for future studies.
Charophytes are non-marine green algae living on the bottom of ancient and Recent lakes and in other non-marine environments. The fossil record of Cretaceous Charophyta considered in this paper includes 56 organ-species, and is the best known of the ancient assemblages in South America. The stratigraphic distribution of these species is outlined using world-wide chronostratigraphic units. Three correlated biogeographic patterns are discussed in the framework of the main geological changes. Early Cretaceous records indicate a high rate of endemism. In the Aptian some barriers of isolation seem to have been broken or bypassed. Despite many cases of widely distributed species, two separate Late Cretaceous biogeographic provinces are recognized: the Andean Province and the South Atlantic Province.
The drainage history of South America, since its breakup and separation from Africa about 100 Ma, shows an exceptionally compelling and pervasive tectonic control that should be true of all the continents, disruption by continental ice sheets excluded. Virtually all of South America's present major drainage developed after its separation From Africa. First, broad domes and aulacogens affected rivers such as the lower Amazon, the Sao Francisco, Uruguay, Rio dr la Plata and their tributaries, and the Colorado and Negro in Argentina. Later the Mid-Miocene uplift of the Andes greatly enlarged the Amazon system and also created the present Magdalena and Paraguay Rivers and most of the Orinoco System. Of all these the Amazon is unique in that its "Andean event" can be dated both at its headwaters and offshore, Of all the major South American rivers, the Parana seems to have the most perfect adjustment to structure, and probably developed after outpouring of the Serra Geral basalts in the late Cretaceous. Examination of the offshore record of South America's passive margin contributed significantly to this analysis, although megashears, plate convergence and impinging oceanic currents have destroyed the offshore record of many rivers. In this era of global geology the ages and paleodrainage of entire continents deserve far more attention from the geologic community than they have received.
Sauropoda is among the most diverse and widespread dinosaur lineages, having attained a near-global distribution
by the Middle Jurassic that was built on throughout the Cretaceous. These gigantic herbivores are characterized by
numerous skeletal specializations that accrued over a 140 million-year history. This fascinating evolutionary history
has fuelled interest for more than a century, yet aspects of sauropod interrelationships remain unresolved. This
paper presents a lower-level phylogenetic analysis of Sauropoda in two parts. First, the two most comprehensive
analyses of Sauropoda are critiqued to identify points of agreement and difference and to create a core of character
data for subsequent analyses. Second, a generic-level phylogenetic analysis of 234 characters in 27 sauropod taxa is
presented that identifies well supported nodes as well as areas of poorer resolution. The analysis resolves six sauropod
outgroups to Neosauropoda, which comprises the large-nostrilled clade Macronaria and the peg-toothed clade
Diplodocoidea. Diplodocoidea includes Rebbachisauridae, Dicraeosauridae, and Diplodocidae, whose monophyly and
interrelationships are supported largely by cranial and vertebral synapomorphies. In contrast, the arrangement of
macronarians, particularly those of titanosaurs, are based on a preponderance of appendicular synapomorphies. The
purported Chinese clade ‘Euhelopodidae’ is shown to comprise a polyphyletic array of basal sauropods and neosauropods.
The synapomorphies supporting this topology allow more specific determination for the more than 50 fragmentary
sauropod taxa not included in this analysis. Their distribution and phylogenetic affinities underscore the
diversity of Titanosauria and the paucity of Late Triassic and Early Jurassic genera. The diversification of Titanosauria
during the Cretaceous and origin of the sauropod body plan during the Late Triassic remain frontiers
for future studies.
The intracratonic basins of northeast Brazil are part of a Cretaceous rift system developed along pre-existing structural trends in the basement during the opening of the South Atlantic Ocean. Sedimentary basins such as those of Sousa, Uirauna-Brejo das Freiras, Araripe, Cedro, Iguatu, Malhada Vermelha, Lima Campos and Ico´ contain a wide variety of vertebrate and invertebrate ichnofossils, and invertebrate, vertebrate and plant fossils, including palynomorphs. Among the clastic continental sediments of these basins, dinosaur footprints are the most abundant vertebrate remains. The dinosaurian ichnofaunas all have the same stratigraphic-time-palaeogeographical context, and represent parts of a widespread megatracksite. Similarities in the lithofacies of the deposits where the footprints occur reflect the same tectonic, climatic and sedimentary processes. The environmental setting was influenced by the initial development of the equatorial Atlantic seaway, with an endemic biota living nearby in ephemeral rivers and shallow lakes in a hot climate.
A data-matrix of 205 osteological characters for 26 sauropod taxa is subjected to cladistic analysis. Two most parsimonious trees are produced, differing only in the relationships betweenEuhelopus,OmeisaurusandMamenchisaurus. The monophyly of the Euhelopodidae (includingShunosaurus) is supported by seven synapomorphies. The Cetiosauridae (Patagosaurus,CetiosaurusandHaplocanthosaurus) is paraphyletic with respect to the Neosauropoda. The latter clade divides into two major radiations—the «Brachiosauria» (Camarasaurus, brachiosaurids and titanosauroids), and the Diplodocoidea (nemegtosaurids, dicraeosaurids, diplodocids andRebbachisaurus). Further evidence for the inclusion ofOpisthocoelicaudiain the Titanosauroidea is presented.Phuwiangosaurus, a problematic sauropod from Thailand, may represent one of the most plesiomorphic titanosauroids. ‘Peg’-like teeth have evolved at least twice within the Sauropoda. The postspinal lamina, on the neural spines of middle and caudal dorsal vertebrae, represents a neomorph rather than a fusion of pre-existing structures. Forked chevrons may have evolved convergently in the Euhelopodidae and the diplodocid-dicraeosaurid clade, or they may have been acquired early in sauropod evolution and subsequently lost in the «Brachiosauria». The strengths and weaknesses of the data-matrix and tree topologies are explored using bootstrapping, decay analysis and randomization tests. Several nodes are only poorly supported, but this seems to reflect the large proportion of missing data in the matrix (46%), rather than an abnormally high level of homoplasy. The results of the randomization tests indicate that the data-matrix probably contains a strong phylogenetic ‘signal’. The relationships of some forms, such asHaplocanthosaurus, are influenced by the inclusion or exclusion of certain taxa with unusual combinations of character states. Such a result suggests that there are dangers inherent in the view that ‘higher’ level sauropod phylogeny can be accurately reconstructed using only a small number of well-known taxa.
Applied dinosaur ichnology, is a field with considerable potential for paleobiological and paleoenvironmental interpretation. Paleontologists have realized the potential of tracks in enhancing paleobiological interpretations pertaining to taxonomy, locomotion, social behaviour, biostratigraphic zonation and evolution. Where the study has really lagged behind is in its application to paleoenvironmental analysis. Recent studies have shown that tracks provide important, paleogeographic evidence of shoreline configuration, paleoslope, absolute water depth and sediment saturation. They may tell one as much about the paleoenvironment as they do about the trackmaker. In addition they have to be considered seriously for their contribution to the bio- or 'dinoturbation' process and for their taphonomic effects. The hitherto unrecognized geographic and stratigraphic abundance of dinosaur (and other) tracks in many regions indicates that they are a persistent rather than occasional feature of the geologic record. As such they warrant greater attention in many paleoenvironmental studies. -from Author
Although sauropods played a major role in terrestrial ecosystems during much of the Mesozoic Era, little effort has been directed toward diagnosing Sauropoda and establishing higher-level interrelationships among sauropods. As a consequence, the origin and evolution of major skeletal adaptations in sauropods has remained largely speculative.The cladistic analysis presented here focuses on higher-level relationships among sauropods. Based on 109 characters (32 cranial, 24 axial, 53 appendicular) for 10 sauropod taxa, the most parsimonious arrangement places four genera (Vulcanodon, Shunosaurus, Barapasaurus, and Omeisaurus) as a sequence of sister-taxa to a group of advanced sauropods, defined here as Neosauropoda. Neosauropoda, in turn, is composed of the sister-clades Diplodocoidea and Macronaria; the latter is a new taxon that includes Haplocanthosaurus, Camarasaurus, and Titanosauriformes. Titanosauriformes includes Brachiosauridae and Somphospondyli, a new taxon uniting Euhelopus and Titanosauria. Among macronarians, the position of Haplocanthosaurus is the least stable as a result of the absence of cranial remains.The basic structure of the phylogeny is resilient to various tests and establishes the evolutionary sequence of many functionally significant sauropod adaptations, such as the digitigrade posture of the manus in neosauropods. Other characteristic sauropod adaptations, such as narrow tooth crowns, increases in length and number of cervical vertebrae, and bifid neural spines, are shown to have evolved more than once. As these results underscore, the higher-level phylogeny of sauropods must be based on a broad sampling of character data.The fossil record of sauropods, although relatively limited during the early phase of the radiation (Late Triassic through Early Jurassic), nonetheless indicates that all major clades were established prior to the Late Jurassic, when substantial faunal interchange among major continental regions was still possible. The functional, temporal, and biogeographic implications of the higher-level phylogeny of sauropods are explored.
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Sketch showing the different diapophyseal laminae in the anterior caudals of Amazonsaurus (A) and Barosaurus AMNH 11657 (B)
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Fig. 18. Sketch showing the different diapophyseal laminae in the anterior caudals of Amazonsaurus (A) and Barosaurus AMNH 11657 (B).
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