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A new brachyrostran with hypertrophied axial structures reveals an unexpected radiation of latest Cretaceous abelisaurids
... In particular, the stratigraphic record of abelisaurids encompasses all Patagonian Upper Cretaceous basins in which continental rocks are preserved (e.g., Neuquén Basin, Somuncura-Cañadón Asfalto Basin, Golfo San Jorge Basin, and Austral Basin). The knowledge of this family of theropods concerning their anatomy, evolutionary history, and phylogenetic relationships has increased notably in recent decades, with the Patagonian records providing the most novel information due to the abundance and diversity of the group to date (e.g., Bonaparte, 1985;Bonaparte & Novas, 1985;Bonaparte et al., 1990;Coria & Salgado, 1998;Coria et al., 2002;Calvo et al., 2004;Canale et al., 2009;Novas et al., 2013;Gianechini et al., 2015Gianechini et al., , 2021Filippi et al., 2016Filippi et al., , 2018bMéndez et al., 2018Méndez et al., , 2022Cerroni & Paulina-Carabajal, 2019;Cerroni et al., 2020;Aranciaga-Rolando et al., 2021;Baiano et al., , 2022. ...
... Publicación Electrónica -2022 -Volumen 22(2): 58-70 (Filippi et al., 2016) and Llukalkan aliocranianus , as well as isolated brachyrostran and furileusaurian remains (Méndez et al., 2018 ...
... A phylogenetic analysis was conducted to evaluate the position of this specimen within Abelisauridae. The character matrix of Gianechini et al. (2021) was used for context, which in turn is a modified version of previous datasets GIANECHINI ET AL.: UNUSUAL ABELISAURID VERTEBRA FROM PATAGONIA The strict consensus shows well-resolved abelisauroid relationships (Fig. 4), although there is variation in the positions of some OTUs with respect to previous results (e.g., Filippi et al., 2016;Gianechini et al., 2021). Concerning ...
The Cerro Overo-La Invernada area in north Patagonia has provided a rich record of Cretaceous continental tetrapods in the last two decades, mainly from the Bajo de la Carpa Formation (Upper Cretaceous, Santonian). The dinosaur fauna from this area is diverse, including several new taxa, with abelisaurid theropods particularly abundant. Recently, a new isolated caudal vertebra (MAU-Pv-CO-598) was here
recovered. Although fragmentary, it shows features that differentiate it from other abelisaurid remains previously found in this area. It is considered a mid-caudal vertebra and is mainly characterized by a longitudinal groove on the ventral surface of the centrum; a scarcely elevated transverse process with an anteroposteriorly expanded and laterally concave distal end; a longitudinal dorsal crest anteriorly extended from the anterior border of the neural spine; and small tubercles extended from the ends of the zygapophyses, which are considered as accessory interlocking structures between vertebrae. Some characters, such as the dorsal longitudinal crest and the accessory tubercles of the zygapophyses, are present also in the non-brachyrostran abelisaurid Majungasaurus. However, the transverse process is similar to that of caudal vertebrae of non-furileusaur brachyrostrans, such as Ilokelesia, Ekrixinatosaurus, and Skorpiovenator. A phylogenetic analysis here conducted clusters MAU-Pv-Co-598 with the latter three taxa. MAU-Pv-CO-598 comes from lower levels of the Bajo de la Carpa Formation than the furileusaurs Viavenator and Llukalkan. The presence of a specimen with non-furileusaurian affinities in this formation indicates that a possible replacement from non-furileusaur to furileusaur brachyrostrans occurred during the Santonian, after the proposed Turonian faunal
turnover.
... The centrum is craniocaudally shorter than transversely wide, as in many other abelisaurids (figure 3; table 1) but contrasting strongly with the much more elongate caudal cervical centra of many nonabelisaurid ceratosaurs such as Berthasaura leopoldinae [32], Elaphrosaurus bambergi [33][34][35], Limusaurus inextricabilis [36], Masiakasaurus knopfleri [37,38] and Vespersaurus paranaensis [39]. The centrum lacks a ventral keel, as is also the case in Majungasaurus [27] and Viavenator exxoni [28,30]. In ventral view, a marked constriction is observed in the middle part of the centrum, as in caudal cervical vertebrae of many taxa within Abelisauria (= Noasauridae + Abelisauridae) [3,40,41] such as Carnotaurus, Majungasaurus, Viavenator, the generically indeterminate Patagonian mid-Cretaceous abelisaurid MPM-99 [31] and (less markedly) Ekrixinatosaurus novasi [42], Elaphrosaurus [34,35] and Masiakasaurus [37]. ...
... The diapophyses merge with the centrum via the cranial (= anterior) [21] and caudal (= posterior) centrodiapophyseal laminae and with the neural arch via the pre-and postzygodiapophyseal laminae. The diapophyses are dorsally located, as in Majungasaurus [27], Dahalokely [29] and MPM-99, whereas in Carnotaurus [26] and Viavenator [28,30] the diapophyses largely obscure the parapophyses in lateral view. ...
... (e,f ) Carnotaurus sastrei (MACN-CH 894) after [26]. (g,h) Viavenator exxoni (MAU-Pv-LI-530) after [28,30]. (i,j) Abelisauridae indet. ...
Numerous non-avian theropod dinosaur fossils have been reported from the Upper Cretaceous (Cenomanian) Bahariya Formation, Bahariya Oasis, Western Desert of Egypt, but unambiguous materials of Abelisauridae have yet to be documented. Here we report Mansoura University Vertebrate Paleontology Center (MUVP) specimen 477, an isolated, well-preserved tenth cervical vertebra of a medium-sized abelisaurid from the Bahariya Formation. The new vertebra shows affinities with those of other Upper Cretaceous abelisaurids from Madagascar and South America, such as Majungasaurus crenatissimus , Carnotaurus sastrei , Viavenator exxoni and a generically indeterminate Patagonian specimen (Museo Padre Molina specimen 99). Phylogenetic analysis recovers the Bahariya form within Abelisauridae, either in a polytomy of all included abelisaurids (strict consensus tree) or as an early branching member of the otherwise South American clade Brachyrostra (50% majority rule consensus tree). MUVP 477, therefore, represents the first confirmed abelisaurid fossil from the Bahariya Formation and the oldest definitive record of the clade from Egypt and northeastern Africa more generally. The new vertebra demonstrates the wide geographical distribution of Abelisauridae across North Africa during the middle Cretaceous and augments the already extraordinarily diverse large-bodied theropod assemblage of the Bahariya Formation, a record that also includes representatives of Spinosauridae, Carcharodontosauridae and Bahariasauridae.
... The Bajo de la Carpa Formation (Santonian, Upper Cretaceous) is a continental unit belonging to the Neuqu en Group of the Neuqu en Basin, which presents a wide distribution throughout northwestern Patagonia (Garrido, 2010(Garrido, , 2011. This geological unit has yielded a large diversity of terrestrial tetrapods, mainly dominated by dinosaurs (e.g., Woodward, 1896;Bonaparte, 1991;Caldwell and Albino, 2001;Apesteguía, 2004;Gianechini et al., 2011;Filippi et al., 2016;Porfiri et al., 2018;Cruzado-Caballero et al., 2019;Gianechini et al., 2020). Particularly, the theropod fauna from these deposits has a major role in our understanding of the evolution as a whole of the theropod lineage history in South America (see Novas et al., 2013;Holtz, 2021). ...
... Particularly, the theropod fauna from these deposits has a major role in our understanding of the evolution as a whole of the theropod lineage history in South America (see Novas et al., 2013;Holtz, 2021). The non-avian theropod record includes at least three clades, i.e., Abelisauroidea, Megaraptoridae, and Alvarezsauridae (Bonaparte, 1991;Martinelli and Vera, 2007;Ezcurra and M endez, 2009;Filippi et al., 2016;Porfiri et al., 2018;Gianechini et al., 2020). The first one is represented by the small abelisauroid Velocisaurus unicus (Bonaparte, 1991), an indeterminate form (Ezcurra and M endez, 2009), and two new taxa recently published, Viavenator exxoni and Llukalkan aliocranianus (Filippi et al., 2016;Gianechini et al., 2020). ...
... The non-avian theropod record includes at least three clades, i.e., Abelisauroidea, Megaraptoridae, and Alvarezsauridae (Bonaparte, 1991;Martinelli and Vera, 2007;Ezcurra and M endez, 2009;Filippi et al., 2016;Porfiri et al., 2018;Gianechini et al., 2020). The first one is represented by the small abelisauroid Velocisaurus unicus (Bonaparte, 1991), an indeterminate form (Ezcurra and M endez, 2009), and two new taxa recently published, Viavenator exxoni and Llukalkan aliocranianus (Filippi et al., 2016;Gianechini et al., 2020). Concerning megaraptorids, there are two records from the Neuqu en province to date, one of them is Tratayenia rosalesi, based on an associated but partial postcranial skeleton (Porfiri et al., 2018), and the other consists of fragmentary postcranial remains (M endez et al., 2021). ...
The abundant record of theropods from Bajo de La Carpa Formation (Neuquén Group, Santonian), known from the end of the nineteenth century, come from numerous locations within the Neuquén Basin. During the excavation of the titanosaur Bonitasaura salgadoi at the La Bonita fossiliferous site, northwest of Río Negro province Argentina, were recovered three isolated teeth assignable to non-avian theropod dinosaurs. Previous studies of these dental materials suggested that MPCA-Pv-247 corresponds to an indeterminate tetanure possibly related to Orkoraptor, a taxon of uncertain phylogenetic position at that moment, and MPCA-Pv-249 and 251 as possible abelisauroids. Three methods were carried out, namely, a cladistic analysis performed on a dentition-based data matrix, and a discriminant and cluster analyses performed in a large dataset including measurements of non-avian theropod teeth. The results assign for the first time a confidently phylogenetic position to the described dental material. The analysis shows that MPCA-Pv 247 belongs to Megaraptoridae, whereas MPCA-Pv 249 and 251 were recovered as belonging to Abelisauridae, supporting in a reliable way the previous assignments. The results show the presence of Megaraptoridae at La Bonita and, additionally, they represent an evidence of the first direct association of megaraptorids and abelisaurids at the same locality of the Bajo de La Carpa Formation, according to similar associations from other units of the Neuquén Group.
... The fossil record of theropods in the Cretaceous of Patagonia is relatively rich, being represented by at least 35 nominal taxa (Novas, 2009;Novas et al., 2013;Ezcurra and Novas, 2016; Aranciaga Rolando et al., 2021;Gianechini et al., 2021). Among them, the most diverse are the abelisaurids, which are represented by several taxa such as Abelisaurus (Bonaparte and Novas, 1985), Aucasaurus (Coria et al., 2002), Carnotaurus (Bonaparte, 1985), Ekrixinatosaurus (Calvo et al., 2004), Skorpiovenator , Viavenator (Filippi et al., 2016), and the recently described Niebla (Aranciaga Rolando et al., 2021) and Llukalkan . ...
... In order to assess the phylogenetic position of the new specimen, we included and codified it in a recently published data matrix (Filippi et al., 2016), which was assembled from several previous works of ceratosaurs (Allain et al., 2007;Carrano and Sampson, 2008;Sereno and Brusatte, 2008;Canale et al., 2009;Ezcurra et al., 2010;Pol and Rauhut, 2012;Farke and Sertich, 2013;Tortosa et al., 2013). To this data matrix we added characters 417-420 from Aranciaga Rolando et al. (2021) and 421-423 from Gianechini et al. (2021). ...
... Characters 424-431 were newly added based mostly on Paulina-Carabajal (2009). We also included the recodifications and modifications on the data matrix of Filippi et al. (2016) made by Gianechini et al. (2021). However, in contrast with the latter, we retained character 380 as a valid character because we consider that it is informative. ...
The fossil record of abelisaurid theropods in South America is mostly limited to Brazil and Argentina. In Argentina, abelisaurids are generally known from Patagonia, where their record is relatively abundant and includes well-known and complete specimens. However, for Northwestern Argentina, abelisaurids are represented by incomplete and isolated bones and teeth that remain largely unpublished. The aim of this contribution is to report a nearly complete abelisaurid braincase from the Late Cretaceous Los Blanquitos Formation (Campanian), Amblayo Valley, Salta province, Argentina. The specimen shows plesiomorphic features for abelisaurids, including a thin skull roof, absence of skull projections like horns or bulges, and low and narrow parietal eminence that lie at the same level as the sagittal crest. Furthermore, the specimen possesses some autapomorphies that support its status as a new taxon and its small size allows it to be assigned as one of the smallest abelisaurids recorded up to date. The finding of this specimen constitutes the first unequivocal occurrence of an abelisaurid in Northwestern Argentina and brings new evidence concerning the geographic distribution of the clade during Late Cretaceous times in South America.
... The knowledge of this family of theropods has been increased exponentially over the last fifteen years, regarding the osteology (e.g., Bonaparte et al., 1990;Carrano, 2007;O'Connor, 2007;Sampson and Witmer, 2007;Paulina-Carabajal 2011a,b;Burch and Carrano, 2012;Delcourt, 2017;Filippi et al., 2018;Cerroni et al., 2020a,c;Aranciaga-Rolando et al., 2021;Gianechini et al., 2021), evolutive history in a paleobiogeographic context (e.g., Sampson et al., 1998;Sereno et al., 2004;Pol and Rauhut, 2012;Novas et al., 2013;Tortosa et al., 2014;Filippi et al., 2016;Longrich et al., 2017), phylogeny (e.g., Carrano and Sampson, 2008;Canale et al., 2009;Tortosa et al., 2014;Filippi et al., 2016), and several paleobiological aspects (e.g., Sampson and Witmer, 2007;M endez, 2010;Persons and Currie, 2011;Paulina-Carabajal and Succar, 2015;Burch, 2017;Delcourt, 2018;Paulina-Carabajal and Filippi, 2018;Cerroni and Paulina-Carabajal, 2019;Cerroni et al., 2020b;Aranciaga-Rolando et al., 2021;Gianechini et al., 2021). ...
... The knowledge of this family of theropods has been increased exponentially over the last fifteen years, regarding the osteology (e.g., Bonaparte et al., 1990;Carrano, 2007;O'Connor, 2007;Sampson and Witmer, 2007;Paulina-Carabajal 2011a,b;Burch and Carrano, 2012;Delcourt, 2017;Filippi et al., 2018;Cerroni et al., 2020a,c;Aranciaga-Rolando et al., 2021;Gianechini et al., 2021), evolutive history in a paleobiogeographic context (e.g., Sampson et al., 1998;Sereno et al., 2004;Pol and Rauhut, 2012;Novas et al., 2013;Tortosa et al., 2014;Filippi et al., 2016;Longrich et al., 2017), phylogeny (e.g., Carrano and Sampson, 2008;Canale et al., 2009;Tortosa et al., 2014;Filippi et al., 2016), and several paleobiological aspects (e.g., Sampson and Witmer, 2007;M endez, 2010;Persons and Currie, 2011;Paulina-Carabajal and Succar, 2015;Burch, 2017;Delcourt, 2018;Paulina-Carabajal and Filippi, 2018;Cerroni and Paulina-Carabajal, 2019;Cerroni et al., 2020b;Aranciaga-Rolando et al., 2021;Gianechini et al., 2021). ...
... Specifically in La Invernada, abelisaurids are surprisingly abundant (Fig. 1B). In recent years, two coeval species have been recognized: Viavenator exxoni (Filippi et al., 2016) and Llukalkan aliocranianus (Gianechini et al., 2021), as well as indeterminate isolated brachyrostran remains (M endez et al., 2018). Here we present new abelisaurid remains from the Bajo de la Carpa Formation at La Invernada locality, which, together with the previous records, support this group of theropods as the dominant predator component in this part of Patagonia during Santonian time. ...
Two new specimens of abelisaurid theropods from La Invernada fossil area (Bajo de la Carpa Formation; Santonian) are described. They correspond to an incomplete skull and several postcranial remains. MAU-Pv-LI-582 (skull) shares some morphological traits with other furileusaurs (Viavenator exxoni and Llukalkan aliocranianus) from the same area, as: presence of a rounded knob on the anteromedial border of the supratemporal fossa, large foramina for the caudal middle cerebral veins, and a triangular basisphenoid recess with Llukalkan, and a basituberal web ventrally concave, a large common foramen for the exit of CNs III and IV, and particularly the absence of a caudal tympanic recess with Viavenator. MAU-Pv-LI-665 (vertebrae and ribs) shares some features with Viavenator, such as the presence of a single pneumatic foramen in the mid cervical centrum, and the shape and orientation of the neural spine of the mid dorsal vertebra. These findings, added to the previous ones, not only reveal the abundance of abelisaurids in this geographical area, but also the variety of morphotypes that coexisted during the middle of the Upper Cretaceous, at least in the north of Argentine Patagonia.
... Elaphrosaurus, Limusaurus, and Pycnonemosaurus; Rauhut and Carrano, 2016;Delcourt, 2017;Wang et al., 2017). However, some disagreement on the base of Abelisauridae still persists, reflected, for instance, in the controversial phylogenetic position of Eoabelisaurus, Genyodectes, Genusaurus, and Dahalokely (Pol and Rauhut, 2012;Farke and Sertich, 2013;Filippi et al., 2016;Longrich ...
... Here, we have incorporated two characters from Baiano et al. (2020), and two new characters related to the first phalanx of pedal digit IV (see supplementary information). Moreover, we have added two OTUs to the original databases: Huinculsaurus montesi (Baiano et al., 2020) and Viavenator exxoni (Filippi et al., 2016). Finally, we have realized some corrections to the original scorings (see supplementary information). ...
... The new position of the Brazilian abelisaurid differs from recent phylogenies, which recovered it as a brachyrostran along with the South American abelisaurids (e.g. Filippi et al., 2016;Longrich et al., 2017;Delcourt, 2017Delcourt, , 2018Gianechini et al., 2021). Recovering Arcovenator among the carnotaurins was unexpectedly, since it was always regarded as closer to Malagasy and Indian forms (e.g. ...
Abelisauridae is a theropod clade with a wide distribution in the Late Cretaceous of Gondwana. Some of the best preserved abelisaurid specimens were recovered from Patagonia (Argentina) such as Skorpiovenator, Ilokelesia, Carnotaurus and Aucasaurus. Here we describe a dorsal part of a neural spine; a middle caudal vertebra; a distal part of a left metatarsal IV; a complete right phalanx IV-1; left phalanges IV-1, 2 and 3; and a pedal ungual phalanx. These materials were recovered from the same quarry of a recently published indeterminate abelisaurid specimen (MPCN-PV-69). The most distinctive characters are a triangular shape of the distal end of metatarsal IV (present in other abelisauroids); phalanx IV-1 with the proximal surface dorsoventrally tall and the ventral surface wider than the dorsal one causing a medial tilting of bone (set of features considered autapomorphic in Velocisaurus, although is also present in different abelisaurids); phalanx IV-1 and 2 with a ridge which spans from the proximodorsal projection, splits in two branch and surrounds a laterally displaced and obliquely oriented oval hyperextensor pit; a pedal ungual phalanx with two medial and lateral vascular grooves, and lacking a flexor tubercle (abelisauroids synapomorphies). The mentioned feature of phalanges IV-1 and 2 is only found among abelisaurids and is here considered as a possible new synapomorphy of Abelisauridae. Thus, besides they constitute new abelisaurid remains from Patagonia, the new materials provide valuable morphological data that could expand the diagnosis of Abelisauridae.
... Among them, abelisaurids are undoubtedly the bestknown theropods. This group of mid-sized, meat-eating dinosaurs is represented by almost 20 nominate species, half of them from Patagonia (Bonaparte, 1985;Bonaparte and Novas, 1985;Martínez et al., 1986;Coria and Salgado, 1998;Calvo et al., 2004;Canale et al., 2009;Filippi et al., 2016;Cerroni et al., 2020). The increase of osteological knowledge of these theropods has been exponential since the recognition of the family, more than 30 years ago. ...
... The increase of osteological knowledge of these theropods has been exponential since the recognition of the family, more than 30 years ago. However, within the last 15 years, aspects such as evolution in a paleobiogeographic context (e.g., Novas et al., 2013;Tortosa et al., 2014;Filippi et al., 2016;Longrich et al., 2017), phylogenetic relationships (e.g., Carrano and Sampson, 2008;Canale et al., 2009;Tortosa et al., 2014;Filippi et al., 2016), and paleobiology (e.g., Sampson and Witmer, 2007;Persons and Currie, 2011;Méndez 2012aMéndez ,b, 2013Delcourt, 2018;Paulina-Carabajal and Filippi, 2018), have been explored for abelisaurids. ...
... The increase of osteological knowledge of these theropods has been exponential since the recognition of the family, more than 30 years ago. However, within the last 15 years, aspects such as evolution in a paleobiogeographic context (e.g., Novas et al., 2013;Tortosa et al., 2014;Filippi et al., 2016;Longrich et al., 2017), phylogenetic relationships (e.g., Carrano and Sampson, 2008;Canale et al., 2009;Tortosa et al., 2014;Filippi et al., 2016), and paleobiology (e.g., Sampson and Witmer, 2007;Persons and Currie, 2011;Méndez 2012aMéndez ,b, 2013Delcourt, 2018;Paulina-Carabajal and Filippi, 2018), have been explored for abelisaurids. ...
Abelisaurids are among the most abundant and diverse Patagonian Late Cretaceous theropods. Here, we present a new furileusaurian abelisaurid, Llukalkan aliocranianus gen. et sp. nov., represented by cranial remains from the Bajo de la Carpa Formation (Santonian) at La Invernada fossil area, northwestern Patagonia. Features characterizing this taxon include a possible caudal tympanic recess posterior to the columellar recess, a T-shaped lacrimal with jugal ramus lacking a suborbital process, and large foramina for caudal middle cerebral veins widely separated from the median supraoccipital crest. In addition to this, a bulge on the anteromedial border of the supratemporal fossa, tall and posteriorly projected paroccipital processes, basal tubera interconnected distally, a triangular basisphenoid recess, and a single foramen for the sphenoidal artery on the basisphenoid, differentiate Llukalkan from Viavenator exxoni. The latter is the other furileusaurian taxon from the same area and stratigraphic unit. Although the holotype of Llukalkan probably corresponds to a sub-adult—as the lacrimal morphology suggests— the possibility that it represents a juvenile of V. exxoni is discarded based mainly on the presence of a caudal tympanic recess (which is absent in V. exxoni). The probable coexistence of two abelisaurid taxa demonstrates that the abelisaurids were one of the most important—and likely the main—predator component of the ecosystems, not only in this area, but also in all of Patagonia, during the Late Cretaceous.
... Carrano and Sampson (2008) supported the relationship of Xenotarsosaurus to other abelisaurids; however, this taxon was not included in these authors' extensive phylogenetic analysis of Ceratosauria. Indeed, relatively few quantitative phylogenetic analyses have included Xenotarsosaurus (e.g., Tortosa et al., 2014;Filippi et al., 2016;Delcourt, 2017;Delcourt and Iori, 2018); the taxon has been excluded from most others (e.g., Canale et al., 2009Canale et al., , 2016Ezcurra et al., 2010;Pol and Rauhut, 2012;Farke and Sertich, 2013;Gianechini et al., 2015;Briss on Egli et al., 2016;Longrich et al., 2017;Wang et al., 2017;Dal Sasso et al., 2018;Delcourt, 2018;Langer et al., 2019). Consequently, the systematic position of this theropod has remained in doubt. ...
... Moreover, we modified the existing character 202, adding a new state and rearranging states 0 and 1 (see Supplementary Material). We further altered the data matrix by adding Afromimus tenerensis, Huinculsaurus montesi, Viavenator exxoni, and Xenotarsosaurus bonapartei (Martínez et al., 1986;Filippi et al., 2016;Sereno, 2017;Baiano et al., 2020) as new terminal OTUs. ...
... Abelisauridae also shows low internal resolution, with the exception of Eoabelisaurus being recovered as the basalmost abelisaurid, the outgroup to the polytomy generated prior to any a posteriori deletion of taxa. Genusaurus (Accarie et al., 1995) is a fragmentary abelisauroid from the Albian (Early Cretaceous) of France, variously regarded as a noasaurid (Farke and Sertich, 2013;Gianechini et al., 2015;Longrich et al., 2017;Wang et al., 2017;Delcourt, 2018) or within Abelisauridae, as either a basal member of this clade (Tortosa et al., 2014) or close to majungasaurins (Filippi et al., 2016;Delcourt, 2017). In the present analysis, this French abelisauroid is alternatively recovered as the sister taxon of Rugops primus, Kryptops, Abelisaurus, and each member of Brachyrostra (Supplementary Material, Fig. 3C). ...
Xenotarsosaurus bonapartei was the third abelisaurid theropod dinosaur to be named from Argentina. The holotype comprises two partial anterior dorsal vertebrae and a complete right hind limb from the Upper Cretaceous (lower Cenomanian–upper Turonian) Bajo Barreal Formation, central Patagonia, Argentina. The materials display morphological features that undoubtedly position Xenotarsosaurus within Abelisauroidea. Moreover, detailed comparisons with members of that theropod group confirm the close relationship of this taxon to abelisaurids. Here we provide an emended diagnosis of Xenotarsosaurus bonapartei that includes five newly recognized autapomorphies: (1) anterior dorsal vertebrae with large, strongly dorsoventrally developed parapophyses; (2) anterior dorsal vertebrae with well-developed centroprezygapophyseal fossae that are taller dorsoventrally than wide mediolaterally; (3) fibular condyle of femur triangular in shape and projecting posteriorly; (4) well-marked groove on the anterolateral corner of the proximal fibula; and (5) iliofibularis tubercle of fibula distally interrupted by a hook-like shaped concavity. To determine its systematic position within Abelisauroidea, we incorporated Xenotarsosaurus into a phylogenetic analysis, recovering this theropod as a non-carnotaurine abelisaurid more derived than Eoabelisaurus mefi. Xenotarsosaurus displays several plesiomorphic traits when compared with penecontemporaneous abelisaurids from the Neuquén Group. Similarly, other non-avian dinosaur taxa from the Bajo Barreal Formation are frequently postulated as more phylogenetically basal than coeval forms from northern Patagonia. This scenario suggests the potential existence of provincialism in early Late Cretaceous continental vertebrate faunas of southern South America. The present study increases knowledge of abelisaurid systematics, evolution, and paleobiogeography and augments our understanding of the Late Cretaceous dinosaur assemblage of central Patagonia.
... The marks and the punctures on the vertebral centrum can be referred to a theropod dinosaur due to their pattern and distribution. Viavenator exxoni (Filippi et al., 2016) represents the most likely trace-maker candidate among the several theropod and crocodile taxa present in the Bajo de la Carpa Formation fossil record. The fossil feeding traces reported here improve our knowledge about the feeding behaviour of large scavengers in the north of the Neuqu en Basin, at least during the Santonian. ...
... Among predators, possible generators of bite marks include like: megaraptorid theropods, such as Tratayenia rosalesi (Porfiri et al., 2018), and several crocodile taxa, such as Notosuchus terrestris (Smith-Woodward, 1896), Cynodontosuchus rothi (Smith-Woodward, 1896), Comahuesuchus brachybuccalis (Bonaparte, 1991), Peirosaurus tormini (Gasparini et al., 1991), Pehuenchesuchus enderi (Turnes and Calvo, 2005), Neuquensuchus universitas (Fiorelli and Calvo, 2007), and Wargosuchus australis (Martinelli and Pais, 2008). Taking into account the localities of Cerro Overo and La Invernada, additional possible generators of bite marks referred to the Bajo de la Carpa Formation are the abelisaurid Viavenator exxoni (Filippi et al., 2016(Filippi et al., y 2018, the peirosaurid crocodile Kinesuchus overoi (Filippi et al., 2018), and a recently recovered megaraptorid indeterminate specimen MAU-PveCOe659 (L.S.F., personal communication). ...
... Even though the teeth recovered from Viavenator are incomplete, it is estimated that the dimensions of one of these (25e30 mm in height and 10 mm in diameter) are consistent with the punctures found on MAU-PveCOe651. According to Filippi et al. (2016), Viavenator was probably 5 m long and, together with the indeterminate Megaraptoridae specimen MAU-PveCOe659, represented one of the largest carnivores of the Bajo de la Carpa Formation at the time, at least in the northern Neuqu en Basin area. Furthermore, the perforations in Set C are deep and rough punctures in the bone with evidences of marginal fractures around them, also seen in several marks in Set A, a condition more consistent with a large consumer than with a smaller scavenger with a less powerful bite. ...
Bite marks in non-avian dinosaur fossil records can constitute the best evidence of predator-prey interactions even if they are uncommon, ambiguous, or of uncertain origin. In this contribution, we present new evidence of feeding traces on an isolated sauropod element from Bajo de la Carpa Formation outcrops (Upper Cretaceous, Santonian), northern Neuquén province, Patagonia, Argentina. The specimen is composed of a partial dorsal vertebral centrum (MAU-Pv-CO-651; deposited at the Museo Municipal Argentino Urquiza, Rincón de los Sauces, Neuquén, Argentina).We tentatively refer it to an indeterminate titanosaur sauropod due to the presence of an opisthocoelic articulation and an internal pneumatic camellate condition. Three kinds of marks are preserved on the lateroventral face of the centrum: large and deep parallel marks, small and shallow longitudinal marks, and deep oval holes that we tentatively consider as punctures. These fossil marks can be considered to be feeding traces produced by a large-bodied carnivore to deflesh the bone and/or to obtain bone nutrients, probably during a single scavenging event. The marks and the punctures on the vertebral centrum can be referred to a theropod dinosaur due to their pattern and distribution. Viavenator exxoni (Filippi et al., 2016) represents the most likely trace-maker candidate among the several theropod and crocodile taxa present in the Bajo de la Carpa Formation fossil record. The fossil feeding traces reported here improve our knowledge about the feeding behaviour of large scavengers in the north of the Neuquén Basin, at least during the Santonian.
... THE Cretaceous record of abelisaurid theropods in Patagonia is by far the richest of the Southern Hemisphere when compared with other Gondwana landmasses (Novas et al., 2013;Delcourt 2018). Patagonia badlands have yielded a high number of informative abelisaurid specimens, including Abelisaurus (Bonaparte and Novas, 1985), Carnotaurus (Bonaparte 1985), Aucasaurus , Ekrixinatosaurus (Calvo et al., 2004), Skorpiovenator (Canale et al., 2009), and Viavenator (Filippi et al., 2016). Despite the fact that most of these records come from Neuquén province, abelisaurids have also been reported for from Chubut, Santa Cruz, and Río Negro provinces. ...
... Phylogenetic analysis. We scored Niebla in the data matrix of Filippi et al. (2016). To the original data matrix, we add four scapulocoracoid characters (see SI): orientation of the glenoid (Ch. ...
... In such analysis, 176 more parsimonious trees (MPTs) of 865 steps were recovered, with a consistency index (CI) of 0,610 and a retention index (RI) of 0,723. The topology obtained is consistent with those of some previous works (Tortosa et al., 2013;Filippi et al., 2016;Cerroni et al., 2020), in which Ligabueino (Bonaparte 1996) is obtained as the sister taxa of Abelisauroidea, and Eoabelisaurus as the sister taxa of the clade comprising Ligabueino + Abelisauroidea. The enigmatic Austrocheirus (Ezcurra et al., 2010) nests within Noasauridae (Fig. 11), a phylogenetic relationship that is supported by a single character: presence of a flat surface in the anterior face of the tibia (Ch. ...
Abelisaurid theropods are well known in Cretaceous beds along South America, particularly Patagonia. However, the record of latest Cretaceous abelisauroids is still far from satisfactory. Until recently, few taxa were described from Maastrichtian beds: Carnotaurus sastrei and Quilmesaurus curriei, but also perhaps Abelisaurus comahuensis. In this contribution, we describe a new genus and species (Niebla antiqua gen. et sp. nov.), of medium-sized abelisaurid coming from Late Cretaceous (Maastrichtian) beds from Río Negro province, northern Patagonia, Argentina. The paleohistological analysis shows that this individual has reached the somatical maturity and that it represents an adult of a mid-sized abelisaurid. The specimen is represented by a nearly complete braincase, fragmentary jaw and teeth, relatively complete scapulocoracoid, dorsal ribs and incomplete vertebrae. The new taxon is relatively small, much smaller than other coeval abelisaurids such as Carnotaurus and Abelisaurus. The braincase shows autapomorphic features such a dorsoventrally tall basal tuber and postemporal foramen enclosed by parietal and exoccipitals. The scapulocoracoid is notably similar to that of Carnotaurus in having a posterodorsally oriented glenoid, a dorsoventrally expanded and wide coraco-scapular plate, and a very narrow and straight scapular blade. These features are very different from those of other abelisaurids, which may indicate a unique conformation of the pectoral girdle among these South American theropods.
... In dorsal view (Fig. 3C), numerous grooves extend mediolaterally on the dorsal surface of the transverse processes, which have the same D-shape of the previous vertebra. These scar-like ridges are also preserved in Majungasaurus (O' Connor, 2007) and Viavenator (Filippi et al., 2016), which are probably the attachment area for the musculus tendinoarticularis (for crocodiles) or the musculus ascendens thoracicus (for birds) (Organ, 2006). ...
... A similar morphology is observed in several basal neotheropods, including Dilophosaurus (Welles, 1984) and Elaphrosaurus (Rauhut and Carrano, 2016). Huinculsaurus shows a poorly developed dorsocaudal process of the neural spine (dcpns), as in Dilophosaurus, Dahalokely (Welles, 1984;Farke and Sertich, 2013) and Skorpiovenator (MMCH-PV 48), but unlike the well-developed condition of Viavenator (Filippi et al., 2016). ...
... Huinculsaurus lacks the dorsocranial process of the neural spines present in the dorsal vertebrae of Dahalokely and Viavenator (Farke and Sertich, 2013;Filippi et al., 2016Filippi et al., , 2017. The peculiar Dshape of the dorsal view of the transverse processes of Huinculsaurus is also present in the posterior dorsals of most abelisauroids like Dahalokely, Carnotaurus, Majungasaurus, Masiakasaurus, Eoabelisaurus (MEF-PV-3990), Skorpiovenator (MMCH-PV 48) and Ilokelesia (Bonaparte et al., 1990;Coria and Salgado, 1998;O'Connor, 2007;Carrano et al., 2011;Farke and Sertich, 2013), which differs from the triangular shape observed in Elaphrosaurus (Rauhut and Carrano, 2016) and various basal neotheropods (e.g, Raath, 1977;You et al., 2014) or the rectangular shape seen in tetanurans (e.g. ...
A new ceratosaurian theropod dinosaur, Huinculsaurus montesi gen. et sp. nov., is described here. This taxon is based on the last three dorsal vertebrae and the first and second sacral vertebrae found in association at Aguada Grande, Neuquén Province, Argentina. Although fragmentary, Huinculsaurus shows a unique mix of features which differentiates it from all other theropods, including the sympatric abelisaurid Ilokelesia, and is diagnosed by prezygapophyseal articular facets twice longer than wide, anterior centroparapophyseal lamina strongly developed as an extensive lateral lamina in the posterior dorsal vertebrae, pneumatic foramina located ventrally to the postzygodiapophyseal lamina in the posterior dorsal vertebrae, posteriorly tapering postzygapophysis pointed posteriorly, and an accessory lamina bisecting the parapophyseal centrodiapophyseal fossa in the posterior dorsal neural arches. Phylogenetic analyses recovered Huinculsaurus as most closely related to the Late Jurassic Elaphrosaurus than to other Cretaceous abelisauroids, suggesting the persistence of the elaphrosaurine lineage in South America up to the early Late Cretaceous.
... In order to assess the phylogenetic position of Tralkasaurus, we included and codified it in a recently published data matrix (Filippi et al., 2016; see Appendix 1), which was assembled by several previous works of ceratosaurs (Allain et al. ...
... Viavenator (Filippi et al., 2016), in which the parapophyses are dorsoventrally tall and relatively stout. Majungasaurus (O'Connor, 2007) and an innominate abelisaurid (MCF-PVPH-237, have parapophyses relatively narrow compared with the aforementioned abelisaurids; however Tralkasaurus differs from Majungasaurus and the innominate abelisaurid in being notably narrow and markedly rod-like. ...
... We included Tralkasaurus in the data matrix published recently by Filippi et al. (2016). Because the original dataset has several Operational Taxonomic Units (OTUs) which are highly fragmentary and uninformative (e.g., Camarillasaurus, Sanchez-Hernández and Benton, 2014; Cerro Bayo taxon, Genusaurus, Accarie et al., 1995, Pol andRauhut, 2012; La Bouchard taxon, Allain and Pereda-Suberbiola, 2003;Kryptops maxilla, Farke and Sertich, 2013;Laevisuchus, Rauhut and Carrano, 2016;Tarascosaurus, Le Loeuff and Buffetaut, 1991), or having doubtful ceratosaur affinities (Porcieux specimen, Buffetaut et al., 1988;postcranium of Kryptops, Novas et al., 2013) were pruned with the aim to obtain a higher resolution within Abelisauridae. ...
... However, the dorsal view is not visible to assess the presence of an interlocking between the neural spines, similar to the handle caudal vertebrae in ankylosaurs (Coombs, 1995;Arbour, 2009). Viavenator also has a system of accessory interspinous articulation (Filippi et al., 2016(Filippi et al., , 2018. Although, such structures in Viavenator are subparallel and dorsoventrally narrow bony projections and are not comparable with those observed in Concavenator, which are dorsoventrally broader. ...
... It is slightly wider in the dorsal part. The anterior surface has a hook-like process, similar to those in Compsognathus (Peyer, 2006), Dilophosaurus (Welles, 1984) or Viavenator (Filippi et al., 2016), but more ventrally placed. This process is interpreted as a ligament attachment structure. ...
... This feature is also present in the anterior-most caudal vertebrae as well; (2) imbrication between dorsal neurapophyses. Although, as abovementioned, this imbrication is also observed in Viavenator (Filippi et al., 2016(Filippi et al., , 2018, the morphology of the accessory interspinous structure is different; ...
Concavenator corcovatus is represented by a single and almost complete and articulated skeleton, MCCM-LH 6666, from the Las Hoyas fossil site (Lower Cretaceous, Spain). The axial skeleton only lacks some caudal vertebrae whereas presacral and sacral regions are totally articulated. Concavenator shows several unusual features associated to the axial skeleton such as some hypertrophied neurapophyses in both dorsal and caudal regions, a development of accessory processes in the neural spines, and a variable morphology of the dorsal neurapophyses. The results show several allosauroid synapomorphies in the axial region such as (1) constriction in all dorsal vertebral centra (2) expanded prezygocentrodiapophyseal fossa in dorsal vertebrae; (3) chevrons with broad and transversally flattened distal ends; and (4) strongly curved, L-shaped middle chevrons. Concavenator shows several autapomorphic features that include: (1) two hypertrophied dorsal and caudal neurapophyses; (2) imbricated dorsal neurapophyses with anterior processes and a morphology that changes from acute and anteroposteriorly short to rectangular and anteroposteriorly wide backwardly; (3) anterior and posterior accessory processes in the anterior caudal neurapophyses; and (4) deeply excavated lateral groove in the posterior caudal vertebrae.
... This feature is commonly observed in noasaurids (Carrano et al., 2002;Carrano et al., 2011;Farke and Sertich, 2013), as well as in some abelisaurids (e.g. O'Connor, 2007;M endez, 2014;Filippi et al., 2016). The cprf is distinct from the MACN-622, in which the cprf is smaller and located lateroventrally to the neural channel (Frankfurt and Chiappe, 1999). ...
... Those features differ from Dahalokely (Farke and Sertich, 2013), in which the eprl is convex (as in abelisaurids), and Laevisuchus (Carrano et al., 2002, figure 7), in which this lamina is concave. Recently, Dahalokely was moved from basal noasaurids (Farke and Sertich, 2013;Tortosa et al., 2014;Gianechinni et al., 2015;Canale et al., 2016) and grouped with Rahiolisaurus as a basal brachyrostran abelisaurid (Filippi et al., 2016;Rauhut and Carrano, 2016). Although the phylogenetic analysis recovered Dahalokely as a basal noasaurid, the assignment of Dahalokely as abelisaurid is consistent with some morphological features on the cervical vertebra, such as the posterior position of the neural spine (anteriorly located in noasaurids), and the development of the cprf, which is restrict in abelisaurids (e.g., O'Connor, 2007;M endez, 2014;Filippi et al., 2016). ...
... Recently, Dahalokely was moved from basal noasaurids (Farke and Sertich, 2013;Tortosa et al., 2014;Gianechinni et al., 2015;Canale et al., 2016) and grouped with Rahiolisaurus as a basal brachyrostran abelisaurid (Filippi et al., 2016;Rauhut and Carrano, 2016). Although the phylogenetic analysis recovered Dahalokely as a basal noasaurid, the assignment of Dahalokely as abelisaurid is consistent with some morphological features on the cervical vertebra, such as the posterior position of the neural spine (anteriorly located in noasaurids), and the development of the cprf, which is restrict in abelisaurids (e.g., O'Connor, 2007;M endez, 2014;Filippi et al., 2016). When compared with noasaurids, these fossae occupy most of the anterior region of the neural arch (e.g., Carrano et al., 2011). ...
The study of pneumatization along axial series of theropods is mostly based on isolated and fragmented specimens. Among abelisauroids, so far the pneumatization of vertebrae was only recognized by external aspects and the morphology of internal pneumatic structures is restricted to the observation of broken regions. Here we describe and provide μCT-scan of one vertebra recovered from the Adamantina Formation (Campanian-lower Maastrichtian) of the Bauru Group, from Brazil. The specimen (DGM 929-R) comprises a cervical vertebra, which is assigned to Noasauridae based on the anteriorly-placed neural spine, and the developed centroprezygapophyseal fossae. The internal structures show regular branching pattern of septae, wide chambers with at least 3 ramifications, and pneumatic pedicles connecting wide, deep fossae of the neural arch, which are indicative of a polycamerate centrum and a procamerate neural arch. Comparisons with other internal structures revealed by tomographic studies and broken regions of cervical series of other theropod specimens show a more diverse arrangement of pneumatic chambers. In addition, a discussion of the internal camerate pneumatic morphology of previously studied theropod cervical vertebrae in the light of the new information revealed by the new material is presented.
... The vertebrate fossil record of the Bajo de la Carpa Formation, where outcrops appear scattered throughout different areas of northern Patagonia, consists of crocodyliforms (Woodward, 1896;Gasparini, 1982;Bonaparte, 1991;Fiorelli and Calvo, 2007;Martinelli et al., 2012), snakes (Woodward, 1901;Caldwell and Albino, 2002), turtles (Lapparent de Broin and De la Fuente, 2001), non avian dinosaurs (Bonaparte, 1996;Apesteguía, 2004;Porfiri and Calvo, 2006;Martinelli and Vera, 2007;Porfiri et al., 2008;Ezcurra and M endez, 2009;Filippi et al., 2014Filippi et al., , 2016M endez et al., 2015), and birds (Alvarenga and Bonaparte, 1992;Chiappe and Calvo, 1994). ...
... Among the theropod fauna, four different small-sized theropod taxa were described, the basal abelisauroid Velocisaurus unicus (Bonaparte, 1996), the alvarezsaurid Alvarezsaurus calvoi (Bonaparte, 1996), the enantiornithine Neuquenornis volans (Bonaparte, 1996) and the basal bird Patagopteryx deferrariisi (Alvarenga and Bonaparte, 1992). In this regard, medium-large sized theropod remains correspond to abelisaurids (Porfiri and Calvo, 2006;Ezcurra and M endez, 2009;Filippi et al., 2014Filippi et al., , 2016M endez et al., 2015), and tetanurans (Porfiri et al., 2008;M endez et al., 2015). In this manner, the specimen described here constitutes the second record of abelisaurid theropod recovered from the Bajo de la Carpa Formation in the La Invernada area (Fig. 1). ...
... Abelisaurid theropods are the best known carnivorous dinosaurs of Gondwana with more than a dozen species nominated (Bonaparte, 1985;Bonaparte and Novas, 1985;Martínez et al., 1986;Coria and Salgado, 1998;Sampson et al., 1998;Coria et al., 2002;Kellner and Campos, 2002;Wilson et al., 2003;Calvo et al., 2004;Coria, 2001;Sereno and Brusatte, 2008;Canale et al., 2009;Novas et al., 2010;Tortosa et al., 2013;Filippi et al., 2016). However, the sacrum is only well known in Carnotaurus (Bonaparte et al., 1990;M endez, 2010) and partially in Majungasaurus (O'Connor, 2007), Rajasaurus (Wilson et al., 2003) and MCF-PVPH-237 (Coria et al., 2006), and the furcula is only known in Majungasaurus (Burch and Carrano, 2012). ...
Several remains of an abelisaurid theropod including a nearly complete sacral complex articulated with both ilia, the distal boot of the pubes, the furcula, teeth, and fragments of transverse processes of caudal vertebrae was discovered in the La Invernada fossil site, northern Patagonia from the Bajo de la Carpa Formation (Santonian). The sacrum exhibit features typical of abelisauroids as narrowing of the middle sacral centra, fused neural spines forming a continuous sheet and ventral bow of the sacrum, in lateral view. The furcula represents de first mention of this bone for a South American abelisaurid. The morphology observed in the transverse processes with distal end projected forward and sagittal ridge on the ventral surface allows its taxonomic assignment to the clade Brachyrostra.
... Because the poor preservation of this sector, no sutures are distinguished between elements, so it is not possible to determine the participation of the supraoccipital in the dorsal edge of the foramen magnum. In Majungasaurus the contribution of the supraoccipital in the foramen magnum has been confirmed through CT scans (Sampson and Wtimer, 2007), although in most abelisaurids this feature is unclear due the sutures are indistinguishable (Wilson et al., 2003;Paulina Carabajal, 2011a, b;Filippi et al., 2016). The supraoccipital crest is well-developed and originates in a zone located about 20 mm above the dorsal edge of the foramen magnum, extending vertically in dorsal direction until contacting the parietal eminence. ...
... In the preliminary description of Viavenator (Filippi et al., 2016) were discussed the implications of the phylogenetic position of this taxon. The phylogenetic analysis performed in that work found Viavenator in an intermediate placement between Cenomanian-Turonian brachyrostran abelisaurids (e.g., Skorpiovenator and Ekrixinatosaurus) and Campanian-Maastrichtian brachyrostran abelisaurids (e.g. ...
... Carnotaurus and Aucasaurus). Related to this was commented that Viavenator presents highly-derived postcranial characters, which are shared with Carnotaurus and Aucasaurus, and a relatively plesiomorphic skull in comparison with these two taxa (Filippi et al., 2016). This interesting combination of features can be characterized in detail, based on the exhaustive osteological description made here. ...
The complete osteology of the abelisaurid Viavenator exxoni, from the Bajo de la Carpa Formation (Santonian, Upper Cretaceous) is described. Viavenator is characterized by a series of autapomorphies, including: transversely compressed parietal depressions on both sides of the supraoccipital crest; ventral edges of the paraoccipital processes located above the level of the dorsal edge of the occipital condyle; basioccipital-opisthotic complex about two and a half times the width and almost twice the height of the occipital condyle, in posterior view; well-developed crest below the occipital condyle, diverging ventrally and defining the subcondylar recess; deeply excavated and sub-circular basisphenoidal recess, with its major axis transversely oriented; basipterygoid processes horizontally placed with respect to the cranial roof and located slightly dorsally to the basal tubera; mid and posterior cervical centra with slightly convex lateral and ventral surfaces; hyposphene-hypanthrum articular complex present from dorsal 2 onward; presence of an interspinous accessory articular system in middle and posterior dorsal vertebrae; presence of a pair of pneumatic foramina within the prespinal fossa in anterior caudal vertebrae; distal end of the scapular blade posteriorly curved. Particularly, Viavenator shows plesiomorphic cranial characters, i.e. flat frontals lacking domes or horns, combined with derived postcranial characters, e.g. the interspinous accessory joint system of dorsal vertebrae. This combination between plesiomorphic and derived traits suggests that Viavenator is a transitional form, which is an idea supported by its intermediate stratigraphic and phylogenetic placement between the basal and older (e.g. Skorpiovenator, Ilokelesia) and derived and younger members of the clade (e.g. Aucasaurus, Carnotaurus).
... The authors made a few comparisons between Pycnonemosaurus and other abelisaurids to describe this South American giant. However, the relationship of Pycnonemosaurus with other abelisaurids remained uncertain until 2014 (Tortosa et al., 2014), when a phylogenetic analysis nested this taxon among carnotaurine abelisaurids () this was recently revised as Furileusaura (Filippi et al., 2016). Herein I present a new description of the type specimen of Pycnonemosaurus nevesi with previously undescribed materials that include three transverse processes and provide comparisons with other theropod taxa, beyond the ones used byKellner & Campos (2002). ...
... Herein I present a new description of the type specimen of Pycnonemosaurus nevesi with previously undescribed materials that include three transverse processes and provide comparisons with other theropod taxa, beyond the ones used byKellner & Campos (2002). Additionally, I discuss the phylogenetic position of Pycnonemosaurus in the context of the recently published analysis of ceratosaurian dinosaurs (Filippi et al., 2016).Theropoda Marsh, 1881Ceratosauria Marsh, 1884Abelisauridae Bonaparte & Novas, 1985Furileusaura Filippi et al., 2016Pycnonemosaurus nevesiKellner & Campos, 2002Holotype. The holotype consists of an incomplete post-cranial skeleton (DGM 859-R) housed in the Museu de Ciências da Terra (Earth Sciences Museum), Rio de Janeiro, Brazil. ...
... The centra are amphicoelous as in other abelisaurids (Méndez, 2014), Masiakasaurus and Ceratosaurus (Madsen & Welles, 2000, plate 17) with the anterior surfaces slightly more concave than the posterior ones. The chevron facets are ventrally prominent and the ventral surfaces have a shallow longitudinal sulcus, as seen in Masiakasaurus, Eoabelisaurus, Aucasaurus, Carnotaurus, Ilokelesia, Viavenator (Filippi et al., 2016) and Majungasaurus (O'Connor, 2007) whereas Ekrixinatosaurus and Rajasaurus have a low ventral keel. The neural arches generally resemble those of other South-American abelisaurids with a dorsally inclined transverse process and an anterior distal projection. ...
Abelisaurid theropods were most abundant in the Gondwana during the Cretaceous Period. Pycnonemosaurus nevesi was the first abelisaurid dinosaur described from the Bauru Group (Brazil, Upper Cretaceous). Nevertheless, its initial description was based on the comparison of a restricted number of remains with other abelisaurids. In this paper, I present a new description of the morphology of Pycnonemosaurus nevesi, including three new caudal transverse processes and a discussion of several new characteristics based on perspectives derived from recently described abelisauroids. Pycnonemosaurus nevesi differs from other abelisaurids based on the following features: a pubis with a small rounded foot and a ventrally-bowed anterior distal end; posterior caudal vertebrae with a hook-shaped transverse process that has an anterodistal expansion that is short and bowed; a strong and massive tibia with a well-developed lateral malleolus that is ventrally expanded. The unfused sutures represent signs of skeletal immaturity, but the specific ontogenetic stage is still uncertain. The current phylogenetic analysis suggests strongly relationship within Pycnonemosaurus and the most-derived abelisaurids (e.g Carnotaurus and Aucasaurus).
... Abelisaurus is recovered as the basal-most taxon of a clade that includes the classic majungasaurines, such as Indosaurus, Majungasaurus and Rajasaurus. Also, in the case of Arcovenator we retrieved it in a position different from recent phylogenetic analyses, since it is placed at the base of the clade Brachyrostra instead of within Majungasaurinae (Tortosa et al. 2014;Filippi et al. 2016;Longrich et al. 2017;Delcourt 2017;Wang et al. 2017;Baiano et al. 2020;Gianechini et al. 2021). In particular, Skorpiovenator was recovered as a nonfurileusaurian brachyrostran more derived than Ilokelesia and Ekrixinatosaurus, differing from several previous phylogenetic analyses that retrieved it along with one or both of the latter taxa ( Absolute and GC frequencies of the bootstrap are below 50, except for Neotheropoda and all abelisaurids more deeply nested than Eoabelisaurus. ...
... Canale et al. 2009;Pol & Rauhut 2012;Farke & Sertich 2013;Rauhut & Carrano 2016;Delcourt 2017Delcourt , 2018Longrich et al. 2017; Zaher et al. 2020;Gianechini et al. 2021;Ibiricu et al. 2021). Finally, Furileusauria consists of Santonian-Maastrichtian Patagonian taxa(Filippi et al. 2016), with Aucasaurus and Niebla as sister taxa and the latest-branching abelisaurids.All nodal supports are low and the majority of nodes have a Bremer support of 1. Only the nodes Averostra and Ceratosauria have values of 3. Within Abelisauridae, several internal nodes have Bremer values of 2 (see Supplemental materialFig. ...
Skorpiovenator bustingorryi is a derived abelisaurid theropod represented by a fairly complete skeleton from the Late Cretaceous sedimentary beds of north-western Patagonia. Although some features were described in the original paper, mainly related to the skull, the appendicular anatomy remains undescribed. The aim of the present contribution is to provide a detailed description and analysis of the available appendicular bones, including comparisons with other ceratosaurian theropods close to Skorpiovenator. In this way, new autapomorphies emerged to further distinguish Skorpiovenator from its relatives. Furthermore, a comprehensive phylogenetic analysis was performed and several characteristics of the hind limb, in particular some of the autopodium, resulted in the identification of new apomorphic traits for Ceratosauria and Abelisauridae. These features might prove to be useful for future phylogenetic analyses and may help to resolve the still confusing and debated internal relationships of abelisaurid theropods.
... Both vertebral centra are similar to that of other abelisaurids (e.g., Bonaparte et al., 1990;Kellner and Campos, 2002;O'Connor, 2007;Méndez, 2014;Filippi et al., 2016); they are spool-shaped, amphicoelous, medially compressed and without pneumatic foramina over the lateral surfaces. The articular facets are rounded; however, the posterior facet of C7 is slight oval-shaped (probably by its more posterior position in the series), as can be seen in the most complete caudal series of Pycnonemosaurus and Aucasaurus but very distinct from those of Arcovenator, Majungasaurus and Rajasaurus, which have an elliptical outline, well-defined in anterior and posterior surfaces (Wilson et al., 2003;O'Connor, 2007;Méndez, 2014;Tortosa et al., 2014;Delcourt, 2017). ...
... The major angle (transverse process/horizontal plane) among abelisaurids occur in Carnotaurus, Aucasaurus and Ekrixinatosaurus, with angle reaching more than 40 • (Méndez, 2014). In Pycnonemosaurus, Skorpiovenator, Viavenator, and also in Kurupi, the inclination ranges between 30 • and 40 • (Méndez, 2014;Filippi et al., 2016;Delcourt, 2017). The transverse process of the (Coria and Salgado, 1998;O'Connor, 2007;Novas et al., 2010). ...
The Late Cretaceous Marília Formation (Bauru Group, Bauru Basin) is a geological unit that occurs on São Paulo, Minas Gerais, Goiás, and Mato Grosso do Sul states, Brazil. This formation consists predominantly of paleosols developed in a semiarid/arid environment and recent reappraisal of its formerly known members reduced its lithological composition and geographical distribution. Hence, the Marília Formation has a very sparse vertebrate fossil record without named species so far. In this contribution we describe a new abelisaurid theropod (Dinosauria) from this unit, namely Kurupi itaata gen. et sp. nov., discovery in the Municipality of Monte Alto, western São Paulo State. The holotype MPMA 27-0001/02 consists of three caudal vertebrae and the partial pelvic girdle. Kurupi itaata gen. et sp. nov. shares with other South American abelisaurids fused ischia and caudal vertebrae with long and laterodorsally oriented transverse processes, with fan-shaped distal ends. Autapomorphies of the new theropod include the variation of ∼15º of the inclination of the transverse process between the first (C1) and seventh (C7) caudal vertebra; C1 with anterolaterally projected triangular process placed below the proximodistal mid-portion of the transverse process, and a notch at the anterodistal portion of the transverse process, between a shelf-like process and the anterodistal corner of the transverse process; and anterior caudal vertebrae (present in C1 and C7, inferred in the others) with a cuneiform process, anterodorsally projected, located on the dorsal surface of the transverse process. Phylogenetic analysis recovered Kurupi itaata gen. et sp. nov. among abelisaurid theropods, but was nested in an unresolved massive polytomy of the entire clade. Taphonomic traits on the studied specimens corroborate previous proposals for the paleoenvironmental context of the Marília Formation. Kurupi itaata gen. et sp. nov. was about 5 meters long, with a rigid tail, and cursorial locomotion as indicated by its a muscles attachment and bones anatomy. This new taxon contributes to the knowledge of the Maastrichtian continental fauna of Brazil and increases the diversity of medium-sized abelisaurids in western Gondwana.
... Dentro desse contexto, esses autores revisaram os caracteres de matrizes já publicadas (e.g. Carrano & Sampson, 2008, Filippi et al., 2016, sugerindo que alguns caracteres deveriam ser mudados ou mesmo excluídos (e.g. caracteres sem verificação do desenvolvimento alométrico do plano corporal). ...
... Em outras palavras, a compreensão da relação de parentesco entre os abelissaurídeos tornou-se mais sólida em pesquisas que utilizaram diferentes bases de dados evidenciando uma maior coerência nas topologias ( Fig. 1) (e.g. Canale et al., 2009, Carrano & Sampson, 2008, Delcourt, 2017, Filippi et al., 2016, Longrich et al., 2017, Pol & Rauhut, 2012Rauhut & Carrano, 2016, Tortosa et al., 2014. ...
Abelisauridae is a broad dinosaur family of Theropoda that includes large extinct carnivores as
well as extant birds. The distribution is mostly in the southern hemisphere, although some specimens are
found in Europe. The phylogenetic relationships of the abelisaurids have been improved, but there is still
some disagreement regarding the inclusion of some groups in the family, which deserve attention. The
body plan of the abelisaurids is conservative among the group, but they have a large cranial disparity.
They also tend to develop cranial structures such as horns, thick skull bones, and cornified covering.
The variety of cranial soft tissues associated with skeletal features suggests that abelisaurids may have
had low-stress headbutting behavior. The Brazilian record is still scarce, and there are only two known
species from different geological units. Even so, it is possible to observe that the abelisaurid diversity
in Brazil was large.
... However, since the time of its original description, several new abelisaurid discoveries have been made, and a revision of the specimen and comparisons with those discoveries is needed. Nevertheless, it is possibleperhaps even likelythat Xenotarsosaurus will still be resolved within Abelisauridae, as originally proposed (Martínez et al., 1986) and latterly supported in other studies (see Filippi et al., 2016). The most significant feature of this theropod is, perhaps, the full co-ossification of the tibia with the proximal tarsals, a character also observed in Aucasaurus garridoi . ...
... The cervical vertebra is almost complete. Based on the position of the parapophyses, the projection of the diapophysis, the inclination of the articular surfaces and comparison with well-preserved abelisauroid cervical sequences [e.g., Carnotaurus and Viavenator (Méndez, 2014;Filippi et al., 2016Filippi et al., , 2018], this specimen is considered to be a middle-posterior cervical vertebra. The anterior articular surface is dorsoventrally depressed, whereas the posterior surface is more rounded in profile, similar to that seen in Dahalokely tokana (Farke and Sertich, 2013) and Viavenator, and unlike the more circular anterior and posterior articular surfaces of Carnotaurus, Ekrixinatosaurus novasi (Calvo et al., 2004b), Ilokelesia aguadagrandensis (Coria and Salgado, 2000) and ...
In this paper, we present an updated revision of fossil vertebrates from the Chubut Group, Golfo San Jorge Basin, while also describing some new remains. Extensive exposures of both Lower and Upper Cretaceous sedimentary sequences are present in central Patagonia. These outcrops have, over the past several decades, yielded a varied vertebrate fauna, including fishes, turtles, crocodyliforms, pterosaurs, and dinosaurs, currently herein characterized and described. Although vertebrate diversity in the Chubut Group in central Patagonia is remarkable, the most abundant vertebrates recovered are dinosaurs. The Matasiete Formation (Hauterivian?–Albian) is markedly less prolific in terms of fossils discoveries than either the Bajo Barreal Formation (Cenomanian–early Turonian) or the recently recognized Lago Colhué Huapi Formation (Coniacian–Maastrichtian). The Bajo Barreal fauna is, at a high level, typical of coeval Gondwanan faunas. However, interestingly, several taxa occupy a basal position within their respective groups. The Lago Colhué Huapi Formation has produced a more derived vertebrate fauna, again similar to those from other Gondwanan regions. Finally, in a broad context, the new materials described augment our understanding of Cretaceous terrestrial vertebrate assemblage of central Patagonia and add to the generally meager record of vertebrate in the Cretaceous of the Southern Hemisphere.
... The skull of Carnotaurus is exaggeratedly short and deep compared with those other taxa of the same clade. The skull of Abelisaurus was largely reconstructed in the snout as well as in the posterior area 1,3,38 , and taphonomic 15 . The phylogenetic position of Chenanisaurus is from Longrich et al. 24 distortion has modified the proportions and several contacts between elements are missing such as the jugal articulations 3,38 . ...
... Both majungasaurini Majungasaurus and Rajasaurus normandensis have a single medial horn formed by the frontal and frontal/nasal, respectively 28,48 , whereas the brachyrostran Carnotaurus has two frontal horns laterally oriented 17 , Aucasaurus has the lateral margins of frontal elevated in the orbital region, and Viavenator exxoni has almost flattened frontals 51 . The flattened frontals of Ekrixinatosaurus novasi 52 and probably of Skorpiovenator suggest the basal position of these two taxa in relation to Furileusaura as proposed by Filippi et al. 15 . ...
Ceratosaur theropods ruled the Southern Hemisphere until the end of the Late Cretaceous. However, their origin was earlier, during the Early Jurassic, a fact which allowed the group to reach great morphological diversity. The body plans of the two main branches (Noasauridae and new name Etrigansauria: Ceratosauridae + Abelisauridae) are quite different; nevertheless, they are sister taxa. Abelisaurids have lost the ability to grasp in the most derived taxa, but the reduced forelimb might have had some display function. The ontogenetic changes are well known in Limusaurus which lost all their teeth and probably changed the dietary preference at maturity. The results presented here suggest that abelisaurids had different soft tissues on the skull. These tissues might have been associated with evolution of a strong cervicocephalic complex and should have allowed derived taxa (e.g.
Majungasaurus and Carnotaurus) to have low-displacement headbutting matches. The ability to live in different semi-arid environment plus high morphological disparity allowed the ceratosaurs to become an evolutionary success.
... The cultriform process, formed probably only by the parasphenoid, is a delicate and short, rod-shaped structure, unlike the blade-shaped and elongate cultriform processes observed in other non-coelurosaur theropods such as Allosaurus (UUVP 5961), Piveteausaurus (MNHN 1920-7), Sinraptor (Currie and Zhao, 1993a;Paulina-Carabajal and Currie, 2012), or abelisaurids (e.g., Sampson and Witmer, 2007;Paulina-Carabajal, 2011b;Filippi et al., 2016). In Murusraptor, the base of the process is laterally compressed and solid, and it is excavated dorsally by a longitudinal AMEGHINIANA -2017 -Volume 54 (5): 617 -640 groove, although its base is smooth. ...
... Similar cavities are known in abelisauroids, such as Aucasaurus (MCF-PVPH 236), Ilokelesia (MCF-PVPH 35), Ekrixinatosaurus (MUCPV 294) (Paulina-Carabajal, 2011a: fig. 4),and Viavenator (MAU-Pv-LI-530;Filippi et al., 2016), and in the carcharodontosaurids Carcharodontosaurus(Coria and Currie, 2002a) and Giganotosaurus (MUCPV-CH-1). ...
A detailed description of the neuroanatomy of Murusraptor barrosaensis –a mid-sized non-maniraptoran theropod from the Late Cretaceous of north Patagonia – is based on the exceptionally preserved type braincase. CT scans provide new information on the braincase, brain, cranial nerves, encephalic vasculature, and inner ear of this taxon. Worldwide, relatively few non-maniraptoran theropod braincases have been described in detail and the new information reported here is important to better understand the variability of braincase characters within the clade. This study suggests that megaraptorids have a particular brain pattern that is different from those of other non-coelurosaur theropods, such as allosauroids and ceratosaurs, and different from that of some coelurosaurs, such as tyrannosaurids, although sharing more similarities with the latter. The Reptile Encephalization Quotient (REQ) of Murusraptor is within a range between those of Allosaurus and Tyrannosaurus; the Olfactory Ratio (OR) is, however, smaller than the observed in tyrannosaurids and allosauroids. The paleobiological implications on gaze stabilization, hearing, and olfaction in the Argentinean taxon are still poorly understand.
... These included the new species Rugops, Kryptops, Chenanisaurus, and Afromimus (Sereno et al., 2004;Longrich et al., 2017: Sereno, 2017. Although the currently recognized diversity of African abelisaurid species is not as high as it is in South America (Bonaparte & Powell, 1980;Bonaparte & Novas, 1985;Bonaparte, 1985;Bonaparte, 1991;Coria & Salgado, 1998;Coria et al., 2002;Kellner & Campos, 2002;Calvo et al., 2004;Canale et al., 2009;Gianechini et al., 2015Gianechini et al., , 2021Filippi et al., 2016;Langer et al., 2019;Cerroni et al., 2020;Aranciaga-Rolando et al., 2021;Méndez et al., 2021;Ortiz David et al., 2021), Africa can now join South America as an area of particular importance for understanding abelisaur diversity and evolution, and thus for understanding what these theropods reveal about dinosaur evolution, distribution, and extinction more broadly. ...
The Continental African abelisauroid theropod dinosaur fossil record from the Jurassic-Cretaceous periods is becoming increasingly better understood, and offers great insight into the evolution and biogeography of this long-lived group of carnivores. Abelisauroidea is among the most familiar groups of theropod dinosaurs from Gondwana, with fossil records in South America, Australia, India and Africa, along with Europe. The objective of the present study is to review the fossil record of abelisauroids in continental Africa. Based on the literature and records from the online databases “The Paleobiology Database” and “The Theropod Database”, we review the distribution of these theropods in Africa and comment on their evolution. The African continent is a major region of importance when it comes to 26 Abelisauroidea fossil findings, including records of both major subdivisions of the clade: the Abelisauridae and Noasauridae families. The oldest Abelisauroidea fossil record found in Africa dates from the Late Jurassic, while the final records date from the end of the Cretaceous. This indicates that clade was the longest surviving lineage of the large theropods of Africa, and they filled a variety of ecological roles, including apex predators, at the end of the Cretaceous, when tyrannosaurids occupied similar niches in the northern continents.
... Los estratos de esta unidad han aportado números ejemplares fósiles, la mayoría provenientes de la zona de las bardas de la ciudad de Neuquén. Entre los dinosaurios terópodos se encuentran representados los alvarezsáuridos, abelisáuridos y megaraptores, como Achillesaurus manazzonei , Alvarezsaurus calvoi , Velocisaurus unicus Brisson Egli et al., 2016), Viavenator exxonei (Filippi et al., 2016) y Tratayenia rosalesi (Porfiri et al., 2018). En cuanto a los dinosaurios saurópodos, sólo se encuentran representados por los ejemplares holotípicos de Bonitasaura salgadoi (Apesteguía, 2004) y Traukutitan eocaudata (Juárez Valieri y Calvo, 2011). ...
This Doctoral Thesis presents an exhaustive review of the Patagonian alvarezsaurids (Dinosauria, Theropoda). It includes a detailed osteological description of specimens of Patagonykus puertai (Holotype, MCF-PVPH-37), cf. Patagonykus puertai (MCF-PVPH-38), Patagonykinae indet. (MCF-PVPH-102), Alvarezsaurus calvoi (Holotype, MUCPv-54), Achillesaurus manazzonei (Holotype, MACN-PV-RN 1116), Bonapartenykus ultimus (Holotype, MPCA 1290), and cf. Bonapartenykus ultimus (MPCN-PV 738). A phylogenetic analysis and a discussion about the taxonomic validity of the recognized species and the taxonomic assignment of the materials MCF-PVPH-38, MCF-PVPH-102 and MPCN-PV 738 are presented. Different evolutionary and paleobiological studies were carried out in order to elucidate functional and behavioral aspects.
Alvarezsaurus calvoi (MUCPv-54), Achillesaurus manazzonei (MACN-PV-RN 1116), Patagonykus puertai (MCF-PVPH-37) and Bonapartenykus ultimus (MPCA 1290) are valid species due to the presence of many autapomorphies. In this sense, the hypothesis proposed by P. Makovicky and collaborators that Achillesaurus manazzonei is a junior synonym of Alvarezsaurus calvoi is rejected. Likewise, certain morphological evidence allows hypothesizing that Alvarezsaurus calvoi represents a growth stage earlier than skeletal maturity. Specimen MCF-PVPH-38 is referable as cf. Patagonykus puertai, while MCF-PVPH-102 is considered an indeterminate Patagonykinae. In turn, MPCN-PV 738 is assigned as cf. Bonapartenykus ultimus based on the little overlapping material with the Bonapartenykus ultimus holotype.
The results obtained from the mineralogical characterization through the X-ray diffraction method of specimens MPCN-PV 738 and the holotype of Bonapartenykus ultimus (MPCA 1290), allow to suggest that both specimens come from the same geographical area and stratigraphic level.
The phylogenetic analysis, which is based upon the matrix of Gianechini and collaborators of 2018 with the inclusion of proper characters, and the database of Xu and collaborators of 2018, recovered the South American members of Alvarezsauria, such as Alnashetri cerropoliciensis (Candeleros Formation; Cenomanian), Patagonykus puertai (Portezuelo Formation, Turonian-Coniacian), Alvarezsaurus calvoi and Achillesaurus manazzonei (Bajo de La Carpa Formation, Coniacian-Santonian), and Bonapartenykus ultimus (Allen Formation, Campanian-Maastrichtian), nesting within the family Alvarezsauridae. In this sense, the forms that come from the Bajo de La Carpa Formation (Coniacian-Santonian) are recovered at the base of the Alvarezsauridae clade, while Alnashetri cerropoliciensis nests as a non-Patagonykinae alvarezsaurid. Regarding the type specimens of Patagonykus puertai and Bonapartenykus ultimus, they are recovered as members of the Patagonykinae subclade, a group that is recovered as a sister taxon of Parvicursorinae, both nested within the Alvarezsauridae. In addition, the topology obtained allows discerning the pattern, rhythm and time of evolution of the highly strange and derived alvarezsaurian skeleton, concluding in a gradual evolution. The Bremer and Bootstrap supports of the nodes (Haplocheirus + Aorun), [Bannykus + (Tugulusaurus + Xiyunykus)], and Patagonykinae, show indices that represent very robust values for these nodes. Likewise, these values suggest that two endemic clades originated early in Asia, while one endemic clade is observed in Patagonia, i.e., Patagonykinae.
The analysis of the directional trends of the Alvarezsauria clade, tested by means of a own database on body masses based on the Christiansen and Fariña method, subsequently calibrated with the group's phylogeny using the R software, shows two independent miniaturization events in the alvarezsaurid evolution, namely the former originating from the base of the Alvarezsauridae (sustained by Alvarezsaurus), and the latter within the Parvicursorinae. Analysis of the Alvarezsauria dentition reveals possible dental synapomorphies for the Alvarezsauria clade that should be tested in an integrative phylogenetic analysis. The general characterization of the forelimb and a partial reconstruction of the myology of alvarezsaurs demonstrate different configurations for Patagonykinae and Parvicursorinae. The multivariate analyzes carried out from the databases of Elissamburu and Vizcaíno, plus that of Cau and collaborators, show that the Patagonykinae would have had ranges of movements greater than those observed in Parvicursorinae, although the latter would have had a greater capacity to carry out more strenuous jobs. The morphometric analysis of the hindlimb and the use of the Snively and collaborators equations, show that the configuration of this element in Alvarezsauria is indicative of a highly cursorial lifestyle, as well as possible particular strategies for more efficient locomotion. The topology obtained in the phylogenetic analysis that was carried out in this Doctoral Thesis, allowed clarifying the ontogenetic changes observed in the ontogenetic series of the manual ungueal element II-2 within the clade Alvarezsauridae. In addition, the multivariate analysis carried out from the manual phalanx II-2 allows us to infer that alvarezsaurs could have performed functions such as hook-and-pull and piercing, where the arm would function as a single unit. The anatomy and myology of the alvarezsaurian tail show that the caudal vertebrae of alvarezsaurians exhibit a combination of derived osteological features that suggests functions unique among theropods, such as considerable dorsal and lateral movements, as well as exceptional abilities to support distal loading of their long tail without compromising stability and/or mobility.
... Por lo tanto, aunque una redescripción del material está en preparación, la asignación de Xenotarsosaurus dentro de Abelisauridae pare-ce estar bien sustentada. Asimismo, este terópodo es también considerado en distintos análisis filogenéticos como un Abelisauridae, ocupando una posición basal en el grupo (Filippi et al. 2016). ...
En la cuenca del Golfo San Jorge se encuentran unidades de origen continental reunidas en el Grupo Chubut (Barreamiano-Maastrichtiano) que son portadoras de un alto contenido fosilífero. Este registro paleontológico de vertebrados continentales cretácicos de la cuenca es una de los más diversos de América del Sur. Es relativamente escaso al momento en la Formación Matasiete (Aptiano), pero mucho más abundante en las formaciones Bajo Barreal (Cenomaniano temprano-Turoniano tardío) y Lago Colhué Huapi (Conianciano-Maastrichtiano). Incluye una importante cantidad de grupos de vertebrados, destacándose los dinosaurios saurópodos, terópodos y ornitópodos. También están bien documentados otros taxones como cocodrilos y tortugas, pero son escasos hasta el momento los restos de reptiles voladores, anuros y peces. Muchos de los hallazgos son de gran importancia y han contribuido al conocimiento de diferentes grupos y de sus relaciones filogenéticas y paleobiogeográficas. Se describe en este trabajo, solo el registro paleontológico más relevante y especies válidas conocidas hasta el momento.
... Finally, the Bajo de la Carpa Formation in Argentina (e.g. [118][119][120][121][122][123][124][125][126]) preserves an excellent record of Santonian dinosaurs, but these include groups like abelisaurids and elasmarians which are entirely unknown in North America and Asia. ...
During the Cretaceous, diversifications and turnovers affected terrestrial vertebrates experiencing the effects of global geographical change. However, the poor fossil record from the early Late Cretaceous has concealed how dinosaurs and other terrestrial vertebrates responded to these events. I describe two dinosaurs from the Santonian to Early Campanian of the obscure North American paleolandmass Appalachia. A revised look at a large, potentially novel theropod shows that it likely belongs to a new clade of tyrannosauroids solely from Appalachia. Another partial skeleton belongs to an early member of the Hadrosauridae, a highly successful clade of herbivorous dinosaurs. This skeleton is associated with the first small juvenile dinosaur specimens from the Atlantic Coastal Plain. The tyrannosauroid and hadrosaurid substantiate one of the only Late Santonian dinosaur faunas and help pinpoint the timing of important anatomical innovations in two widespread dinosaur lineages. The phylogenetic positions of the tyrannosauroid and hadrosaurid show Santonian Appalachian dinosaur faunas are comparable to coeval Eurasian ones, and the presence of clades formed only by Appalachian dinosaur taxa establishes a degree of endemism in Appalachian dinosaur assemblages attributable to episodes of vicariance.
... Despite widespread agreement that elaphrosaurines are ceratosaurians (Carrano and Sampson, 2008;Delcourt, 2018), the position of Elaphrosaurinae within Ceratosauria remains unclear. Elaphrosaurinae has been placed basal to Neoceratosauria (Wilson et al., 2003;Carrano and Sampson, 2008;Pol and Rauhut, 2012;Tortosa et al., 2014;Gianechini et al., 2015;Brum et al., 2018;Smyth et al., 2020) or in a polytomy with Ceratosauridae + Abelisauroidea (Xu et al., 2009;Farke and Sertich, 2013;Brissón Egli et al., 2016;Canale et al., 2016;Filippi et al., 2016;Delcourt, 2017;Delcourt and Iori, 2018). However, several recent analyses have resolved Elaphrosaurinae as the sister taxon to Noasaurinae within Noasauridae (Rauhut and Carrano, 2016;Wang et al., 2017a;Langer et al., 2019), and we follow this interpretation herein. ...
Elaphrosaurinae is an enigmatic clade of gracile ceratosaurian theropod dinosaurs known from the Late Jurassic of Africa (Elaphrosaurus bambergi) and Asia (e.g., Limusaurus inextricabilis), and the early Late Cretaceous of Argentina (Huinculsaurus montesi). Elaphrosaurinae is often placed within Noasauridae as the sister taxon to Noasaurinae, a clade of small-bodied theropods that lived in South America, Africa, Madagascar and India throughout much of the Cretaceous. Herein, we report the first evidence of Elaphrosaurinae from Australia: a nearly complete middle cervical vertebra from the upper Lower Cretaceous (lower Albian) Eumeralla Formation of Cape Otway, Victoria, Australia. The fact that this site would have been situated at ~76°S towards the end of the Early Cretaceous (~110–107 Ma) implies that elaphrosaurines were capable of tolerating near-polar palaeoenvironments, whereas its age indicates that elaphrosaurines persisted in Australia until at least the late Early Cretaceous. The new Australian elaphrosaurine, in tandem with the recently described Huinculsaurus montesi from the Cenomanian–Turonian of Argentina, implies that the spatiotemporal distribution of Elaphrosaurinae has heretofore been greatly underestimated. Historic confusion of elaphrosaurines with coelurosaurs, especially ornithomimosaurs, coupled with our generally poor understanding of noasaurid evolution, might explain the apparent dearth of fossils of this theropod clade worldwide.
... Conflict between alternative topologies [78, 99,100] means that Berberosaurus was placed in a polytomy with Noasauridae and Abelisauroidea, whereas Eoabelisaurus occupied a polytomy with Ceratosauridae and Abelisauridae. Abelisaurid relationships then followed [101]. ...
The importance of adaptation [1-4] versus organizational constraints [5-7] in shaping common macroevolutionary trends remains unclear [8]. The fossil record is key to this problem, as it provides data on repetitive trait evolution between lineages [4, 8]. However, quantitative analyses investigating these dynamics with fossil data are rare [8]. Herbivory evolved multiple times within Mesozoic dinosaurs [9, 10], allowing analysis of common phenotypic responses to dietary evolution. Whereas repeated patterns of character acquisition [9] and functional changes [11-13] are observed between some herbivorous dinosaur clades, biomechanical studies resolve significant differences between morphologically similar taxa [12-14]. However, previous biomechanical analyses have not accounted for phylogenetic non-independence (e.g., [13-16]) or been restricted to individual clades (e.g., [11, 12, 16]). Here, we use multivariate analysis of biomechanical characters, within a robust phylogenetic context, to investigate functional pathways to herbivory in a large sample of non-avian dinosaurs. Results demonstrate multiple solutions to herbivory. Notably, two fundamentally different modes are observed to evolve independently multiple times, with morphofunctional changes in the skull co-varying with digestive strategy. These modes distinguish between gut-processing sauropodomorphs and theropods tending toward gracile crania and low bite forces and ornithischian taxa exhibiting character complexes associated with extensive oral processing. Although convergence within these subsets of taxa is common, it is not observed between them due to functional constraints imposed during the early evolution of each group. This highlights the hierarchical nature of evolution, with adaptation driving convergence within regions of morphospace delimited by phylogenetic contingency.
... In fact, such taxon names are abundant in dinosaur systematics. To name a just few: Allosauria and Carcharodontosauria are sub-clades of Allosauroidea (e.g., Benson et al., 2010;Carrano et al., 2012), while Brachyrostra and Furileusauria are sub-clades of Abelisauridae (Canale et al., 2008;Filippi et al., 2016), and Eucentrosaura and Pachyrostra are sub-clades of Centrosaurinae (Fiorillo and Tykoski, 2012). Others include Pantyrannosauria and Eutyrannosauria as sub-clades of Tyrannosauroidea (Delcourt and Grillo, 2018), Megalosauria as a sub-clade of Megalosauroidea (Carrano et al., 2012), Eudromaeosauria as a sub-clade of Dromaeosauridae (Longrich and Currie, 2009) and Hadrosauromorpha as a sub-clade of Hadrosauroidea (Norman, 2014). ...
Ornithopod dinosaurs were abundant inhabitants of European islands during the Late Cretaceous. The long history of dinosaur research in Europe has led to the establishment of new taxa for numerous ornithopod specimens that received considerable attention in the literature; however, many of these remain essentially unstudied. This explains why little is known of their potential phylogenetic, ecological and biogeographical importance. Here we provide a reassessment of Orthomerus dolloi, an enigmatic ornithopod taxon that was established on the basis of isolated appendicular elements, including a left tibia, a right femur, a left femur and a metatarsal. The material originates from the uppermost Maastrichtian of southern Limburg (the Netherlands) or adjacent Belgian territory. Despite the fact that they have been known for almost 140 years, none of these elements has been evaluated in detail since their original description. Here we redescribe and illustrate the syntypes of O. dolloi, and compare them to corresponding elements in other latest Cretaceous ornithopods from Europe. The character distribution in O. dolloi is further explored by means of phylogenetic analyses, using a revised ornithopod-wide dataset. The material belongs to at least two, probably conspecific, individuals that show clear hadrosauroid affinities, although the exact placement of the taxon within the clade remains contentious, because it is likely that its elements are osteologically immature. Therefore, the common assignment of O. dolloi to hadrosaurid ornithopods is questionable. Nevertheless, our revision of the material has not identified any autapomorphies, nor a combination of characters that would be indisputably unique among Hadrosauroidea.
... Abelisauridae is one of the most prominent families of mid-sized theropod dinosaurs that inhabited Gondwana and southern Europe in the Late Cretaceous (see Novas et al., 2013 and references therein). Remains including complete braincases are known for several taxa, such as Abelisaurus comahuensis, Carnotaurus sastrei, Skorpiovenator bustingorryi, Viavenator exxoni and Aucasaurus garridoi from Argentina (Bonaparte and Novas, 1985;Bonaparte et al., 1990;Canale et al., 2008;Coria et al., 2002;Filippi et al., 2016), Majungasaurus crenatissimus from Madagascar (Sampson and Witmer, 2007;Sues, 1980), Arcovenator escotae from France (Tortosa et al., 2013), and Indosaurus matleyi, Indosuchus raptorius and Rajasaurus narmadensis from India (Huene et Matley, 1933;Novas et al., 2004;Wilson et al., 2003). However, detailed descriptions of the abelisaurid braincase are available only for a few taxa (i.e. ...
The endocranial morphology of the abelisaurid Carnotaurus sastrei, from the Upper Cretaceous of Patagonia, is studied using X-ray Computed Tomography (CT). The CT scans provided information that allowed the first reconstruction of the brain, inner ear and braincase pneumaticity for this South American taxon. The endocranial morphology confirms that abelisaurids share an overall conformation of the brain and inner ear. However, some traits, such as the height of the dorsal sinuses and the length of the flocculus in the cranial endocast, and a large subsellar recess in the basicranium, appear to characterize the South-American abelisaurids only. Moreover, the olfactory acuity of Carnotaurus resembles that reported for other abelisaurids (e.g., Majungasaurus, Viavenator), suggesting that the sense of smell had an important role. However, some attributes of the endocranial features of Carnotaurus (i.e. development and orientation of the olfactory bulbs and tracts) may imply particular olfactory capacities when compared with other abelisaurids.
... Abelisauridae is one of the most prominent families of mid-sized theropod dinosaurs that inhabited Gondwana and southern Europe in the Late Cretaceous (see Novas et al., 2013 and references therein). Remains including complete braincases are known for several taxa, such as Abelisaurus comahuensis, Carnotaurus sastrei, Skorpiovenator bustingorryi, Viavenator exxoni and Aucasaurus garridoi from Argentina (Bonaparte and Novas, 1985;Bonaparte et al., 1990;Canale et al., 2008;Coria et al., 2002;Filippi et al., 2016), Majungasaurus crenatissimus from Madagascar (Sampson and Witmer, 2007;Sues, 1980), Arcovenator escotae from France (Tortosa et al., 2013), and Indosaurus matleyi, Indosuchus raptorius and Rajasaurus narmadensis from India (Huene et Matley, 1933;Novas et al., 2004;Wilson et al., 2003). However, detailed descriptions of the abelisaurid braincase are available only for a few taxa (i.e. ...
The endocranial morphology of the abelisaurid Carnotaurus sastrei, from the Upper Cretaceous of Patagonia, is studied using X-ray Computed Tomography (CT). The CT scans provided information that allowed the first reconstruction of the brain, inner ear and braincase pneumaticity for this South American taxon. The endocranial morphology confirms that abelisaurids share an overall conformation of the brain and inner ear. However, some traits, such as the height of the dorsal sinuses and the length of the flocculus in the cranial endocast, and a large subsellar recess in the basicranium, appear to characterize the South-American abelisaurids only. Moreover, the olfactory acuity of Carnotaurus resembles that reported for other abelisaurids (e.g., Majungasaurus, Viavenator), suggesting that the sense of smell had an important role. However, some attributes of the endocranial features of Carnotaurus (i.e. development and orientation of the olfactory bulbs and tracts) may imply particular olfactory capacities when compared with other abelisaurids.
... By contrast, in non-dinosaurian dinosauriforms (e.g., Lewisuchus admixtus: PULR 01) and basal saurischians (e.g., Herrerasaurus ischigualastensis: PVSJ 407; Tawa hallae: Nesbitt et al., 2009), the parabasisphenoid is horizontal, with the basal tubera and the base of the basipterygoid processes aligned in the horizontal plane. The ethmoidal elements (sphenethmoids + mesethmoid; see Ali et al., 2008) of Zupaysaurus rougieri are not ossified, as is common in most theropods except Ceratosaurus magnicornis (e.g., Sanders and Smith, 2005), abelisaurids (e.g., Sampson and Witmer, 2007;Paulina-Carabajal, 2011a, 2011bFilippi et al., 2016), some allosauroids (Coria and Currie, 2002;Paulina-Carabajal and Currie, 2012), and tyrannosaurids (e.g., Ali et al., 2008, and references therein). ...
Zupaysaurus rougieri is an early neotheropod from the middle Norian Los Colorados Formation of northwestern Argentina represented by an almost complete skull and several postcranial bones. Most of its braincase morphology has remained obscured by other skull bones and sediment. Additional mechanical preparation and X-ray computed tomography on the single known specimen of Zupaysaurus has allowed a detailed description of the braincase, the cranial endocast, and the inner ear of this Triassic dinosaur. Basal theropod braincases are poorly sampled and there is little information on this region, and even poorer knowledge on the brain and inner ear anatomy of Triassic forms. The virtual reconstruction of the braincase of Zupaysaurus shows anteroventrally oriented, finger-like basipterygoid processes, an elongate and horizontally projected cultriform process, and well-developed preotic pendant, basisphenoid recess, and subsellar recess. The endocranial morphology is partially reconstructed, showing an anteroposteriorly short but dorsoventrally tall cranial endocast, with well-marked demarcations between the forebrain, midbrain, and hindbrain. The inner ear preserves the three semicircular canals, but not the lagena. The posterior semicircular canal is proportionally large when compared with that of other theropods. The new information presented here on Zupaysaurus rougieri contributes to the knowledge of the neuroanatomy of basal theropods and sheds light on the evolutionary patterns of the
braincase morphology in nonavian Theropoda.
... the scarce remains attributable to some of them, the relationships among these taxa and core-noasaurines are controversial and, at least for G. sisteronis and Da. tokana, there is more recent and substantial evidence 4,[17][18][19] suggesting that they do not belong to the Noasaurinae lineage, whereas De. agilis may instead represent a tetanuran theropod 20 . ...
Noasaurines form an enigmatic group of small-bodied predatory theropod dinosaurs known from the Late Cretaceous of Gondwana. They are relatively rare, with notable records in Argentina and Madagascar, and possible remains reported for Brazil, India, and continental Africa. In south-central Brazil, the deposits of the Bauru Basin have yielded a rich tetrapod fauna, which is concentrated in the Bauru Group. The mainly aeolian deposits of the Caiuá Group, on the contrary, bear a scarce fossil record composed only of lizards, turtles, and pterosaurs. Here, we describe the first dinosaur of the Caiuá Group, which also represents the best-preserved theropod of the entire Bauru Basin known to date. The recovered skeletal parts (vertebrae, girdles, limbs, and scarce cranial elements) show that the new taxon was just over 1 m long, with a unique anatomy among theropods. The shafts of its metatarsals II and IV are very lateromedially compressed, as are the blade-like ungual phalanges of the respective digits. This implies that the new taxon could have been functionally monodactyl, with a main central weight-bearing digit, flanked by neighbouring elements positioned very close to digit III or even held free of the ground. Such anatomical adaptation is formerly unrecorded among archosaurs, but has been previously inferred from footprints of the same stratigraphic unit that yielded the new dinosaur. A phylogenetic analysis nests the new taxon within the Noasaurinae clade, which is unresolved because of the multiple alternative positions that Noasaurus leali can acquire in the optimal trees. The exclusion of the latter form results in positioning the new dinosaur as the sister-taxon of the Argentinean Velocisaurus unicus.
... However, in spite of the rich faunal association recovered from the Bajo de la Carpa Formation in the decades from 1890 to 2000, remains of medium to large-sized dinosaurs were not known for this unit, with the exception of the titanosaur Bonitasaura and the later relocation of Rinconsaurus and Overosaurus within the fluvial deposits of the unit (Filippi, 2015). Since the discovery in 2013 of a new fossiliferous site belonging to the Bajo de la Carpa Formation in the northwestern area of Neuqu en Province, located approximately 40 km southwest of the town of Rinc on de los Sauces, the number of known species has increased substantially, including a new faunal association composed of sauropod, theropod and ornithopod dinosaurs, as well as a wide variety of turtles and fishes (Filippi et al., , 2016Cruzado-Caballero et al., 2016b. ...
... The holotype of Viavenator exxoni was found in the outcrops of the Bajo de la Carpa Formation (Santonian, Upper Cretaceous), northwestern Patagonia, and it is hosted at the "Argentino Urquiza" Museum, Rinc on de los Sauces city, Argentina (Filippi et al., 2016). The complete osteology of this species, including general aspects of the braincase morphology, is being described elsewhere (Filippi et al., present issue). ...
The type braincase of Viavenator exxoni (MAU-Pv-LI-530) was recovered complete and isolated from most of the other skull bones. Although the braincase is crossed by numerous fractures, using CT scans allowed the generation of 3D renderings of the endocranial cavity enclosing the brain, cranial nerves, and blood vessels, as well as the labyrinth of the inner ear. Within the abelisaurids, the only taxon with a complete braincase and known endocranial morphology is Majungasaurus crenatissimus, from Africa. In turn, in Argentina, partial endocranial morphology is known for another two Cretaceous forms: Abelisaurus comahuensis and Aucasaurus garridoi. Here, we present the most complete reconstruction of the neuroanatomy for a representative of the clade in South America. These findings add knowledge to the field of theropod paleoneuroanatomy in general, and abelisaurid diversity in particular. Comparisons of Viavenator with other abelisaurids indicate greater similarity with Aucasaurus than with Majungasaurus, suggesting that South American forms shared the same neurosensorial capabilities, which include larger flocculus of the cerebellum and larger olfactory ratios than the form from Madagascar.
Les fossiles des dipneustes sont principalement représentés par des plaques dentaires et des os de la mâchoire, alors que les crânes complets, ou presque complets, sont rares. Ici, nous décrivons un nouveau dipneuste du Santonien (Crétacé supérieur) de la Patagonie Argentine à l’aide de rendus tridimensionnels générés par des tomodensitogrammes. Il s’agit d’un crâne quasi-complet et de matériel postcrânien. Rinconodus salvadori n. gen., n. sp. est diagnostiqué par une combinaison de caractéristiques, telles que : série médiale composée de deux os non appariés, série médio-latérale composée de deux os appariés, série latérale avec au moins un os, bord médial des plaques dentaires plus long que le bord lingual et de même courbure, plaques dentaires supérieures contiguës ou proches les unes des autres avec cinq denticulations, plaques dentaires inférieures largement séparées avec quatre denticulations, première denticulation des plaques dentaires supérieures plus longue et plus mince que les autres denticulations, et courbée postérieurement, première denticulation des plaques dentaires inférieures relativement droite et plus longue que les autres, entre autres. La nouvelle espèce est basée sur les deux premiers crânes de dipneustes Santoniens presque complets d’Amérique du Sud. De plus, les matériaux présentés ici sont les enregistrements les plus récents d’un crâne de dipneuste presque complet et de matériel postcrânien du Crétacé du Gondwana.
Rinconsaurus caudamirus, from the Bajo de la Carpa Formation (Santonian), Río Negro, Argentina, is represented by several axial and appendicular elements from, at least, four specimens. The axial skeleton of this taxon was described in detail in a recent contribution, pending a complete analysis and description of its appendicular skeleton. This contribution focuses on the description of the appendicular skeleton of Rinconsaurus and its phylogenetic relationships, considering the new information provided here. Rinconsaurus clearly differs from other titanosaurs for the presence of several autapomorphic characters and for a unique association of characters, some of which are also present in lognkosaurians, aeolosaurines and saltasaurines titanosaurs, and by having a scapula with a scapular blade angled 65° with respect to the coracoid articulation, similar to that of Bellusaurus, Dreadnoughtus and Muyelensaurus. Equations for estimating body mass in sauropods based on long bone circumference suggest a body mass of at least 3-5 tonnes for the largest individuals of Rinconsaurus, being lighter than saltasaurines, but heavier than aeolosaurines. Rinconsaurus was incorporated into an expanded version of a phylogenetic data matrix along with several ontemporary South American titanosaurs. The resulting data matrix comprises 102 taxa scored for 431 characters, and our phylogenetic analysis retrieves Rinconsaurus as a member of the clade Rinconsauria. For its part, the clade Rinconsauria, in which Aeolosaurini is nested, is recovered within a diverse Lognkosauria. When the resulting trees are time calibrated and taking into account the position of Ninjatitan within Rinconsauria, there results that the possible origin of the clades Lognkosauria and Rinconsauria (among other titanosaur clades) could have occurred towards the beginning of the Early Cretaceous.
Abelisaurids are medium–large-sized theropod dinosaurs that were predominant in the carnivorous fauna during the Late Cretaceous of Gondwana. These predators are abundant in the Cretaceous fossil strata of Patagonia, which yield the best record for this group. In the Late Cretaceous, abelisaurids appear in almost all regions of Gondwana and in all stages, except for the Coniacian, in which they are globally unknown. Here we describe a new abelisaurid, Elemgasem nubilus gen. et sp. nov., from the Portezuelo Formation (Turonian–Coniacian), Patagonia, Argentina. The palaeohistology of the appendicular bones of Elemgasem shows that the holotype was a subadult individual, but had achieved sexual maturity. This taxon is based on several axial and appendicular elements, and is diagnosed by the presence of a marked pattern of rugosity on the lateral surface of the fibula and a dorsoventrally deep lateral wall of the calcaneum. Moreover, the posterior caudal vertebrae have a morphology slightly different from any other abelisaurid. Elemgasem nubilus is recovered as an unstable taxon within Brachyrostra, given that it was recovered as sister taxon of Furileusauria or in several positions within this clade. Despite the problematic phylogenetic relationships of Elemgasem nubilus, it is important because it is the first abelisaurid from the Turonian–Coniacian interval and it increases the diversity of this theropod family at a time of marked turnover in the tetrapod fauna of South America, global climate change, and mass extinction events recorded worldwide in the marine realm.
The recognition of ontogenetic edentulism in the Jurassic noasaurid Limusaurus inextricabilis shed new light on the dietary diversity within Ceratosauria, a stem lineage of non-avian theropod dinosaurs known for peculiar craniomandibular adaptations. Until now, edentulism in Ceratosauria was exclusive to adult individuals of Limusaurus . Here, an exceptionally complete skeleton of a new toothless ceratosaur, Berthasaura leopoldinae gen. et sp. nov., is described from the Cretaceous aeolian sandstones of the Bauru Basin, Southern Brazil. The specimen resembles adult individuals of Limusaurus by the absence of teeth but based on the unfused condition of several elements (e.g., skull, vertebral column) it clearly represents an ontogenetically immature individual, indicating that it might never have had teeth. The phylogenetic analysis performed here has nested Berthasaura leopoldinae as an early-divergent Noasauridae, not closely related to Limusaurus . It represents the most complete non-avian theropod from the Brazilian Cretaceous and preserves the most complete noasaurid axial series known so far. Moreover, the new taxon exhibits many novel osteological features, uncommon in non-avian theropods, and unprecedented even among South American ceratosaurs. These include not only toothless jaws but also a premaxilla with cutting occlusal edge, and a slightly downturned rostral tip. This indicate that B. leopoldinae unlikely had the same diet as other ceratosaurs, most being regarded as carnivorous. As the ontogenetically more mature specimens of Limusaurus , Berthasaura might have been herbivorous or at least omnivorous, corroborating with an early evolutionary divergence of noasaurids from the ceratosaurian bauplan by disparate feeding modes.
Se estudiaron 13 dientes aislados de dinosaurios terópodos provenientes de dos yacimientos cercanos ubicados en la localidad de Paso Córdoba (General Roca, Rio Negro); en ambos casos, los dientes se encontraban en asociación con restos esqueletarios de saurópodos titanosaurios. Estos yacimientos fosilíferos corresponden a la Formación Allen (Campaniano-Maastrichtiano), concretamente a facies de interdunas secas. Mediante caracteres cualitativos y cuantitativos, se han identificado cuatro Morfotipos dentales, el primero asignado al clado Abelisauridae, el segundo a Tetanurae indeterminado, el tercero a Megaraptora, y el último a Theropoda indeterminado. Se efectuó un análisis de componentes principales y un análisis discriminante de los dientes con el objetivo de buscar una organización de los datos a través de las medidas efectuadas, y reducir las dimensiones o número de variables. Los resultados obtenidos fueron consistentes con las asignaciones sistemáticas realizadas a partir de parámetros tradicionales, y coherentes con los análisis filogenéticos vigentes. El Morfotipo 1 presenta los siguientes caracteres compartidos con Abelisauridae: A, margen distal recto en vista lateral; B, dentículos mesiales en forma de gancho; C, dentículos centrales de la carena distal tan altos como anchos en vista lateral; D, dentículos apicales de la carena mesial orientados apicalmente; E, carena mesial extendida hasta el cuello dentario; F, dentículos mesiales centrales tan altos como anchos en vista lateral; y G, dentículos centrales de la carena distal orientados apicalmente. El Morfotipo 2, no permite una asignación clara, pero podemos establecer que estos materiales carecen completamente de caracteres que permitan asignarlos al clado Ceratosauria. Los caracteres que unen al Morfotipo 3 con el clado Megaraptora son: A, contorno basal de la sección transversal de la corona en forma de D o de J; B, superficie cóncava en la cara lingual y adyacente a la carena mesial; y C, carena mesial esplazada mesio-labialmente o labialmente.
Archosaur osteological remains are abundant in Brazil, particularly from the Triassic and Cretaceous strata, but in Jurassic, the record is predominantly represented by ichnofossils. The Upper Jurassic archosaur records comprise the Paralligatoridae Batrachomimus pastosbonensis, from the Pastos Bons Formation (Parnaíba Basin),
remains of Mesoeucrocodylia from the Aliança Formation (Jatobá Basin), and fragments of Dinosauria from the Brejo Santo Formation (Araripe Basin) with a dubious assignment. Here, we present the fi rst undoubted Dinosauria record for the Jurassic of Brazil, MCT 2670-LE, a middle to distal caudal vertebra belonging to a theropod. MCT 2670-LE was excavated in the 60s by prof. Ignacio Machado Brito, being primarily attributed to strata of the Aliança Formation but the rock matrix involving the specimen allows us to correlate MCT 2670-LE to Sergi Formation, marking this specimen as the fi rst archosaur record of this unit. The caudal vertebra is assigned to Carcharodontosauria based on the hourglass shaped centrum and the deep and narrow ventral groove. The specimen provides new data to the paleogeographic distribution of carcharodontosaurians before
the South America-Africa break-up, as well as understanding the theropod faunal turnover of paleoenvironments during the Jurassic-Cretaceous transition in Brazil.
The deposits corresponding to the Upper Cretaceous Neuquén and San Jorge Gulf basins from northern and central Patagonia have provided two of the most complete sequences of terrestrial vertebrate faunas of all Gondwanan landmasses. Among the carnivorous components, the carcharodontosaurid theropods appeared as common elements during the Early Cretaceous and the earliest Late Cretaceous in northern and central Patagonia. Although recorded mostly in the lower Turonian, isolated teeth suggest their presence in younger strata in northern and central Patagonia, reaching the clade in the region as late as the early Maastrichtian. Here, we verify the assignment of such isolated teeth previously identified as belonging to Carcharodontosauridae from the Upper Cretaceous strata of northern and central Patagonia. Using three different methods, namely a cladistic analysis performed on a dentition-based data matrix, and discriminant and cluster analyses conducted on a large dataset of theropod crown measurements, we assign a tooth from Candeleros Formation to carcharodontosaurid theropods and teeth from Cerro Lisandro, Bajo Barreal, Portezuelo, Plottier and Allen formations to abelisaurid theropods. These new reappraisals provide additional evidence about the extinction of Carcharodontosauridae in South America at about the late Turonian–earliest Coniacian as part of a general faunistic turnover event, with the last clear evidence of this lineage in Patagonia coming from the early–middle Turonian.
Carnotaurus sastrei
is perhaps the most iconic representative of the Abelisauridae family. It is known by a fairly complete specimen, recovered from Upper Cretaceous beds of southern Argentina. Here we present a re-study of the skull of Carnotaurus including detailed osteological descriptions, CT scans analyses and comparisons with abelisaurid taxa. Novel information concerning bones that remained undescribed (i.e., palate) is also offered. The present study allowed the recognition of several features, including some new potential autapomorphies diagnostic of Carnotaurus, such as nasolacrimal conduct with an accessory canal, ventral excavation on the quadrate and lateral fossa of the pterygoid. We identify some additional features of Carnotaurus shared with other abelisauroids, including: dorsal row of nasal foramina, lateral fossa on the squamosal, lanceolate vomeropterygoid process of palatine, apneumatic ectopterygoid and narrow and pointed angular process of surangular. CT scans revealed pneumatic recesses in the lacrimal which are similar to those present in other theropods. Furthermore, a striking feature is the presence of a small pneumatic recess on each frontal horn. Carnotaurus provides one of the most complete skulls within Abelisauridae, which allows recognising several traits of potential phylogenetic value and raises new questions regarding variability of cranial pneumaticity among ceratosaurs.
The diversity of Australia’s theropod fauna from the ‘mid’-Cretaceous (Albian–Cenomanian) is distinctly biased towards the medium-sized megaraptorids, despite the preponderance of abelisauroids in the younger but latitudinally equivalent Patagonian theropod fauna. Here, we present new evidence for the presence of ceratosaurian, and specifically abelisauroid, theropods from the Cenomanian Griman Creek Formation of Lightning Ridge, New South Wales. A partial cervical vertebra is described that bears a mediolaterally concave ventral surface of the centrum delimited by sharp ventrolateral ridges that contact the parapophyses. Among theropods, this feature has been reported only in a cervical vertebra attributed to the noasaurid Noasaurus. We also reappraise evidence recently cited against the ceratosaurian interpretation of a recently described astragalocalcaneum from the upper Barremian–lower Aptian San Remo Member of the upper Strzelecki Group in Victoria. Inclusion of the Lightning Ridge cervical vertebra and Victorian astragalocalcaneum into a revised phylogenetic analysis focused on elucidating ceratosaurian affinities reveals support for placement of both specimens within Noasauridae, which among other characters is diagnosed by the presence of a medial eminence on the ascending process of the astragalus. The Lightning Ridge and Victorian specimens simultaneously represent the first noasaurids reported from Australia and the astragalocalcaneum is considered the earliest known example of a noasaurid in the world to date. The recognition of Australian noasaurids further indicates a more widespread Gondwanan distribution of the clade outside of South America, Madagascar and India consistent with the timing of the fragmentation of the supercontinent.
Isolated cervical vertebrae from the mid Cretaceous Kem Kem beds of south east Morocco are referred to the theropod dinosaur clade Abelisauroidea, and represent the first axial remains from this deposit referred to this group. An isolated axis is referred to Abelisauroidea on account of the invaginated spinopostzygapophyseal lamina; the extremely large, projecting and pointed epipophyses; and the anteroposteriorly long, transversely compressed neural spine with a gently convex and unexpanded dorsal margin. In addition, postzygapophyseal facets which completely overhang the centrum posteriorly and lack lateral orientation indicate abelisaurid affinities. An anterior cervical (C4?) is referred to Noasauridae based on an anteriorly-positioned, reduced neural spine and extremely well developed centroprezygapophyseal fossae. This specimen represents both the smallest dinosaur and the first definitive small-bodied dinosaur from the Kem Kem beds. The affinities of the new material are discussed in the context of other abelisauroid remains reported from the Kem Kem assemblage and elsewhere in Africa.
Abelisaurid theropods are well-know from the Cretaceous of several parts of the Southern
Hemisphere, including South America, Madagascar, and Africa, but also in India and Europe. Abelisaurids are high-diverse among other theropods with several cervicocephalic specializations reaching medium/large sizes. In the present contribution, we describe a new abelisaurid (Thanos simonattoi, gen. et sp. nov.) from the São José do Rio Preto Formation, Bauru Group, Brazil (Upper Cretaceous). Thanos differs from other theropods by having a well-developed keel becoming wider and deeper posteriorly on the ventral surface; two lateral small foramina separated by a relative wide wall on each lateral surface of the centrum, and well-developed and deep prezygapophyseal pinodiapophyseal fossae. The closed sutures between the axis and odontoid suggest that Thanos had reached a subadult/adult stage before death. Thanos is phylogenetically related to Brachyrostra abelisaurid. The keel on the ventral axial centrum in abelisauroids is here interpreted as a homoplastic condition that became more pronounced towards the phylogeny. The presence of well-developed keel in Thanos suggests that this taxon could be more derived than other abelisaurids. Finally, even though abelisaurids could reach large sizes, Thanos shared the environment with a larger theropod that was probably close to Megaraptora.
We describe Tratayenia rosalesi gen. et sp. nov., a new megaraptoran theropod dinosaur from the Upper Cretaceous of Patagonia, Argentina. The holotype consists of a well-preserved, mostly articulated series of dorsal and sacral vertebrae, two partial dorsal ribs, much of the right ilium, and pubis and ischium fragments. It was found in a horizon of the Upper Cretaceous (Santonian) Bajo de la Carpa Formation of the Neuquén Group in the Neuquén Basin exposed near the town of Añelo in Neuquén Province of northwestern Patagonia. Phylogenetic analysis recovers Tratayenia within the Gondwanan megaraptoran subclade Megaraptoridae. The new taxon exhibits similarities to other megaraptorids such as Aerosteon riocoloradensis, Megaraptor namunhuaiquii, and Murusraptor barrosaensis, but also presents differences in the architecture of the dorsal and sacral vertebrae and the morphology of the ilium. Tratayenia is the first megaraptoran that unequivocally preserves the complete sequence of sacral vertebrae, thereby increasing knowledge of the osteology of the clade. Moreover, depending on the chronostratigraphic ages of the stratigraphically controversial megaraptorids Aerosteon and Orkoraptor burkei, as well as the phylogenetic affinities of several fragmentary specimens, the new theropod may be the geologically youngest megaraptorid or megaraptoran yet discovered. Tratayenia is also the largest-bodied carnivorous tetrapod named from the Bajo de la Carpa Formation, reinforcing the hypothesis that megaraptorids were apex predators in southern South America from the Turonian through the Santonian or early Campanian, following the extinction of carcharodontosaurids.
In the last decades, the Argentinian ornithopod record has been increased with new and diverse bone remains found along all the Upper Cretaceous. Most of them are very incomplete and represent taxa of different size. As result, the studies about the palaeobiodiversity of the Ornithopoda clade in South America are complex. In this paper, new postcranial remains of an indeterminate medium-sized ornithopod from the Santonian Bajo de la Carpa Formation (Rincón de los Sauces, Neuquén province) are presented. They present diagnostic features of the Ornithopoda clade, and several characters that relate them with other Argentinian ornithopods, especially with the medium-sized members of the Elasmaria clade sensu Calvo et al. (2007) (Macrogryphosaurus and Talenkauen). The postcranial material allows to identificate at least three different ontogenetic stages: adult, subadult more immature and subadult. These bones are the first record of Ornithopoda for the Bajo de la Carpa Formation and one of the very scarce Santonian records of this clade in South America. The diversity of the Late Cretaceous South American ornithopods presents two clear distributions: the Cenomanian-Santonian was characterized by small and medium euiguanodonts and elasmarian; and the Campanian-Maastrichtian by the medium sized elasmarian and large sized hadrosaurids.
Resumen
The Late Cretaceous (Maastrichtian) Lameta Formation of central India has yielded dissociated elements of a variety of predatory dinosaurs, most of them coming from a quarry named the "Carnosaur bed." The materials were described by Huene and Matley nearly 70 years ago. They recognized nine theropod species, which they sorted out into the theropod subgroups "Carnosauria" and "Coelurosauria". Huene and Matley also described a considerable amount of theropod hindlimb bones (e.g., femora, tibiae, metatarsals, and pedal phalanges) that they could not refer to any of these species, but vaguely interpreted as corresponding to "allosaurid" or "coelurosaurid" theropods. We reviewed the available collection of Cretaceous theropods from Bara Simla housed at the Geological Survey of India, Calcutta, arriving to the following conclusions: 1) Indosuchus and Indosaurus are abelisaurids, as recognized by previous authors, but available information is not enough to judge whether they are synonyms; 2) Laevisuchus indicus is a small abelisauroid, related to Noasaurus and Masiakasaurus on the basis of their peculiar cervical vertebrae; 3) the controversial taxa " Compsosuchus", " Dryptosauroides", " Ornithomimoides", and " Jubbulpuria" are represented by isolated vertebrae corresponding to different portions of the neck and tail, and also exhibit abelisauroid features; 4) hindlimb bones originally referred to as "allosaurid" and "coelurosaurian" also exhibit abelisauroid characters, and bones of large size are tentatively referred to as corresponding to Indosuchus or Indosaurus, whereas some pedal bones of smaller size may belong to Laevisuchus; 5) two kinds of abelisaurid feet are apparent: one in which the phalanges of digit III and IV are robust, and another type in which the phalanges of digit IV are transversely narrow and dorsoventrally deep. This review demonstrates that all of the theropod elements discovered at the "Carnosaur bed" belong to a single theropod clade, the Abelisauroidea
We describe the new basal abelisauroid dinosaur Austrocheirus isasii gen. et sp. nov. from the Late Cretaceous Pari Aike Formation of southwestern Patagonia, Argentina. The preserved remains include manual bones, a distal tibia, and some pedal and axial elements. Austrocheirus is differentiated from other basal theropods by the presence of metacarpal III with a dorsoventrally compressed shaft and posteriorly displaced collateral tendon fossae located at the same level of the proximal end of distal condyles, and pedal phalanges with a conspicuous longitudinal crest delimitating the dorsal margin of the distal collateral tendon fossae. A cladistic analysis recovered the new species as more derived than Ceratosaurus and Berberosaurus, but within a polytomy at the base of Abelisauroidea, an assignment supported by two abelisauroid synapomorphies: distal end of tibia with a planar vertical scar for the reception of the ascending process of the astragalus that occupies most of its anterior surface and is medially bounded by the longitudinally oriented facet; and scar for the reception of the ascending process with a median vertical ridge, which imbeds into a crescentic vertical groove on the posterior surface of the ascending process of the astragalus forming an interlocking tibiotarsal articulation. Furthermore, Austrocheirus represents the first known medium-sized Late Cretaceous abelisauroid bearing non-atrophied hands. The evidence provided here suggests that the strong reduction of the forelimb recorded in derived abelisaurids is not directly correlated with their increased body-size, but it seems to be an evolutionary event exclusive to this lineage within Ceratosauria.
In traditional Linnaean taxonomy, classifications are constructed and maintained principally as dichotomous hierarchies. In phylogenetic taxonomy, such hierarchies are restricted to monophyletic groups defined explicitly on the basis of common ancestry. A definitional configuration termed a node-stem triplet is described that stabilizes the relationship between a given taxon and its subordinate taxa. I outline a rationale within phylogenetic taxonomy for construction of a stable taxonomic framework, as demonstrated by application to the higher-level taxonomy of Dinosauria.
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.
Diverse crocodyliforms have been discovered in recent years in Cretaceous rocks on southern landmasses formerly composing Gondwana. We report here on six species from the Sahara with an array of trophic adaptations that significantly deepen our current understanding of African crocodyliform diversity during the Cretaceous period. We describe two of these species (Anatosuchus minor, Araripesuchus wegeneri) from nearly complete skulls and partial articulated skeletons from the Lower Cretaceous Elrhaz Formation (Aptian-Albian) of Niger. The remaining four species (Araripesuchus rattoides sp. n., Kaprosuchus saharicus gen. n. sp. n., Laganosuchus thaumastos gen. n. sp. n., Laganosuchus maghrebensis gen. n. sp. n.) come from contemporaneous Upper Cretaceous formations (Cenomanian) in Niger and Morocco.
Abelisaurids are a clade of large, bizarre predatory dinosaurs, most notable for their high, short skulls and extremely reduced forelimbs. They were common in Gondwana during the Cretaceous, but exceedingly rare in the Northern Hemisphere. The oldest definitive abelisaurids so far come from the late Early Cretaceous of South America and Africa, and the early evolutionary history of the clade is still poorly known. Here, we report a new abelisaurid from the Middle Jurassic of Patagonia, Eoabelisaurus mefi gen. et sp. nov., which predates the so far oldest known secure member of this lineage by more than 40 Myr. The almost complete skeleton reveals the earliest evolutionary stages of the distinctive features of abelisaurids, such as the modification of the forelimb, which started with a reduction of the distal elements. The find underlines the explosive radiation of theropod dinosaurs in the Middle Jurassic and indicates an unexpected diversity of ceratosaurs at that time. The apparent endemism of abelisauroids to southern Gondwana during Pangean times might be due to the presence of a large, central Gondwanan desert. This indicates that, apart from continent-scale geography, aspects such as regional geography and climate are important to reconstruct the biogeographical history of Mesozoic vertebrates.
We report the discovery of basal abelisaurid and carcharodontosaurid theropods from the mid Cretaceous (Aptian-Albian, ca. 112 Ma) Elrhaz Formation of the Niger Republic. The abelisaurid, Kryptops palaios gen. et sp; nov., is represented by a single individual preserving the maxilla, pelvic girdle, vertebrae and ribs. Several features, including a maxilla textured externally by impressed vascular grooves and a narrow antorbital fossa, clearly place Kryptops palaios within Abelisauridae as its oldest known member. The carcharodontosaurid, Eocarcharia dinops gen. et sp. nov., is represented by several cranial bones and isolated teeth. Phylogenetic analysis places it as a basal carcharodontosaurid, similar to Acrocanthosaurus and less derived than Carcharodontosaurus and Giganotosaurus. The discovery of these taxa suggests that large body size and many of the derived cranial features of abelisaurids and carcharodontosaurids had already evolved by the mid Cretaceous. The presence of a close relative of the North American genus Acrocanthosaurus on Africa suggests that carcharodontosaurids had already achieved a trans-Tethyan distribution by the mid Cretaceous.
Sinraptor dongi is a large theropod from the upper Shishugou Formation (Jurassic) of Xinjiang in northwestern China. The holotype includes a well-preserved braincase that recently benefited from additional preparation. The ossified ethmoidal elements are U-shaped in cross-section. When placed in anatomical position in the braincase, an unossified space remains between the sphenethmoid and the orbitosphenoid, suggesting there was a cartilaginous septosphenoid when the animal was alive. The morphology of the endocranial cavity and pneumatic recesses was studied using a latex endocast and CT scans. This led to the recognition of some traits that have not been previously described. The presence of a well developed caudal tympanic recess (generally considered as characteristic of coelurosaurs) is particularly interesting, as is the internal morphology of the basisphenoidal recess and its associated pneumatic cavities. There is a longitudinal passage connecting the lateral tympanic recess with the basisphenoidal recess that probably had both pneumatic and vascular functions. Endocranially, there is no medullar eminence, and the opening for the floccular recess is hourglass-shaped. The volume of the endocranial cavity, excluding the olfactory tract and bulbs, is 95 ml, and the encephalization quotient falls within the range calculated for other basal tetanurans. The angles formed between forebrain, midbrain and hindbrain are similar to those in carcharodontosaurids (Carcharodontosaurus and Giganotosaurus), although the relative positions of cranial nerves II-IV varies amongst these taxa. Cranial nerves IX, X and XI pass through a single half-moon-shaped opening. Within Allosauroidea, the cranial endocast of Sinraptor is morphologically more similar to those of Allosaurus, Carcharodontosaurus and Giganotosaurus than to that of Acrocanthosaurus.
Quilmesaurus curriei Coria, 2001 (Dinosauria, Theropoda). Its taxonomic validity and phylogenetic relationships. A comparative analysis of the Cretaceous theropod Quilmesaurus curriei from the Río Negro province, Patagonia, Argentina was performed in order to elucidate its phylogenetic relationships. Quilmesaurus was considered as basal Tetanurae by Coria (2001), however, Kellner & Campos (2002) suggested that this theropod could be a possible Abelisauria. In our analysis, we observed that the lack of fusion of the tibia with the astragalus-calcaneum is not an exclusive character for Ceratosauria; moreover, the mediodistal crest of femur is commonly well developed in Abelisauroidea. The great development of the distally expanded cnemial crest and the asymmetrical distal end of the tibia are characteristics of Abelisauridae. Finally, other characters like a distally directed process at the end of the cnemial crest and the asymmetry in the origin of the expansion of the malleolii in distal tibia are regarded as synapomorphies of Carnotaurinae. Therefore, Quilmesaurus curriei is considered to belong to Abelisauridae, and it is possibly a member of Carnotaurinae. On the basis of the available evidence, it is not possible to identify autapomorphic characters that allow validating Quilmesaurus curriei, and for this reason we consider it as a nomen vanum.
The Abelisauridae are a family of mainly Cretaceous theropod dinosaurs with a wide distribution across the Gondwanan land masses. Although their presence in Europe was reported twenty-five years ago, it has often been considered as controversial largely because of the incompleteness of the available speci-mens. We report here the discovery of well-preserved abelisaurid material, including a highly diagnostic braincase, at a Late Cretaceous (late Campanian) locality in the Aix-en-Provence Basin, near the eponym city in south-eastern France. A new abelisaurid taxon is erected, Arcovenator escotae gen. nov., sp. nov., on the basis of cranial and postcranial material. A phylogenetic analysis reveals that the new Abelisauridae from Provence is more closely related to taxa from India and Madagascar than to South American forms. Moreover, Genusaurus, Tarascosaurus and the previous Late Cretaceous discoveries are identified as basal abelisaurids. Contrary to previously proposed palaeobiogeographical models of abelisaurid evolution, the presence of the new taxon in Europe suggests that Europe and Africa may have played a major role in abelisaurid dispersal, which apparently involved crossing marine barriers.
Patagonia has yielded the most comprehensive fossil record of Cretaceous theropods from Gondwana, consisting of 31 nominal species belonging to singleton taxa and six families: Abelisauridae, Noasauridae, Carcharodontosauridae, Megaraptoridae nov. fam., Alvarezsauridae, and Unenlagiidae. They provide anatomical information that allows improved interpretation of theropods discovered in other regions of Gondwana. Abelisauroids are the best represented theropods in Patagonia. They underwent an evolutionary radiation documented from the Early Cretaceous through to the latest Cretaceous, and are represented by the clades Abelisauridae and Noasauridae. Patagonian carcharodontosaurids are known from three taxa (Tyrannotitan, Giganotosaurus and Mapusaurus), as well as from isolated teeth, collected from Aptian to Cenomanian beds. These allosauroids constituted the top predators during the mid-Cretaceous, during which gigantic titanosaur sauropods were the largest herbivores. Megaraptorans have become better documented in recent years with the discovery of more complete remains. Megaraptor, Aerosteon and Orkoraptor have been described from Cretaceous beds from Argentina, and these taxa exhibit close relationships with the Aptian genera Australovenator, from Australia, and Fukuiraptor, from Japan. The Gondwanan megaraptorans are gathered into the new family Megaraptoridae, and the Asiatic Fukuiraptor is recovered as the immediate sister taxon of this clade. Although megaraptorans have been recently interpreted as members of Allosauroidea, we present evidence that they are deeply nested within Coelurosauria. Moreover, anatomical information supports Megaraptora as more closely related to the Asiamerican Tyrannosauridae than thought. Megaraptorans improve our knowledge about the scarcely documented basal radiation of Gondwanan coelurosaurs and tyrannosauroids as a whole. Information at hand indicates that South America was a cradle for the evolutionary radiation for different coelurosaurian lineages, including some basal forms (e.g., Bicentenaria, Aniksosaurus), megaraptorans, alvarezsaurids less derived than those of Laurasia, and unenlagiids, revealing that Gondwanan coelurosaurs played sharply differing ecological roles, and that they were taxonomically as diverse as in the northern continents. The unenlagiids represent an endemic South American clade that has been recently found to be more closely related to birds than to dromaeosaurid theropods. Analysis of the theropod fossil record from Gondwana shows the highest peak of origination index occurred during the Aptian–Albian and a less intense one in the Campanian time spans. Additionally, peaks of extinction index are recognized for the Cenomanian and Turonian–Coniacian time spans. In comparison, the Laurasian pattern differs from that of Gondwana in the presence of an older extinction event during the Aptian–Albian time-span and a high origination rate during the Cenomanian time-bin. Both Laurasian and Gondwanan theropod records show a peak of origination rates during the Campanian.
The Cretaceous terrestrial strata of the Neuquén Basin (northern Patagonia, Argentina) are described together with their tetrapod records. Six local tetrapod assemblages are identified: Amargan (Barremian–Early Aptian), Lohancuran (Late Aptian–Albian), Limayan (Cenomanian–Early Turonian), Neuquenian (Late Turonian–Coniacian), Coloradoan (Santonian–Early Campanian) and Allenian [Late Campanian–Early Maastrichtian (= Alamitense = Alamitian SALMA)]. The last of these includes records from north-eastern Patagonia.
The ornithopod dinosaur Gasparinisaura cincosaltensis gen. et sp. nov. is described. This new taxon from the Upper Cretaceous of northwest Patagonia (Argentina) represents the first report of basal iguanodontian ornithopods from South America. Gasparinisaura shares with the Dryomorpha the out-turned jugal-postorbital articulation, prominent lateral primary ridge in maxillary teeth, well-developed brevis shelf and metatarsal I reduced or absent. It retains a well-developed quadratojugal, low maxillary crowns, and a laterally compressed ischial shaft. The new taxon Euiguanodontia is erected to include Gasparinisaura cincosaltensis and the Dryomorpha (=Dryosauridae + Ankylopollexia).
A nearly complete, well-preserved maxilla of an abelisaurid theropod from the early Late Cretaceous (middle Cenomanian-Turonian) Lower Member of the Bajo Barreal Formation of Chubut, Argentina represents the first definitive member of the abelisaurid clade from pre-Senonian (Coniacian–Maastrichtian) deposits. The new maxilla shares derived characters with the maxillae of Carnotaurus and Majungatholus, and with AMNH 1955, a maxilla previously referred to Indosuchus, suggesting that it pertains to the abelisaurid subclade Carnotaurinae. Abelisaurus shares apomorphic characters with Carnotaurinae, but many of these characters are also found in the carcharodontosaurid allosauroid Giganotosaurus. As it is known only from cranial material lacking carnotaurine synapomorphies, Abelisaurus may represent a late-surviving carcharodontosaurid derivative.
The presence of the Bajo Barreal predator in the early Late Cretaceous indicates that the origin of Abelisauridae had occurred by then. The occurrence of the new maxilla is nearly concurrent with the accepted interval of tectonic divergence between South America and Africa. Its discovery thus weakens support for the recent hypothesis that the abelisaurid clade could not have penetrated Africa. The known occurrence of Abehsauridae may reflect a former pan-Gondwanan distribution, and is thus of limited utility in the support of Late Cretaceous paleogeographic hypotheses.
Geophysical evidence strongly supports the complete isolation of India and Madagascar (Indo-Madagascar) by ∼100 million years ago, though sparse terrestrial fossil records from these regions prior to ∼70 million years ago have limited insights into their biogeographic history during the Cretaceous. A new theropod dinosaur, Dahalokely tokana, from Turonian-aged (∼90 million years old) strata of northernmost Madagascar is represented by a partial axial column. Autapomorphies include a prominently convex prezygoepipophyseal lamina on cervical vertebrae and a divided infraprezygapophyseal fossa through the mid-dorsal region, among others. Phylogenetic analysis definitively recovers the species as an abelisauroid theropod and weakly as a noasaurid. Dahalokely is the only known dinosaur from the interval during which Indo-Madagascar likely existed as a distinct landmass, but more complete material is needed to evaluate whether or not it is more closely related to later abelisauroids of Indo-Madagascar or those known elsewhere in Gondwana.
Some fragmentary dinosaur remains from the uppermost Hauterivian–Barremian La Paloma Member of the Cerro Barcino Formation of northern Chubut, Argentina are described. Together with the fauna from the La Amarga Formation of Neuquén, Argentina, this material represent the oldest known Cretaceous dinosaur fauna from South America. It includes remains of a probable titanosaurian sauropod and an abelisaurian, probable abelisaurid, theropod. This is the oldest record of titanosaurs from South America and the oldest record of abelisaurids globally. The presence of both small-bodied noasaurids in the La Amarga Formation and medium-sized–large abelisaurids in the Cerro Barcino Formation, in the middle Lower Cretaceous of Argentina, indicates that abelisaurian diversification began well before the final fragmentation of Gondwana. Whereas this explains the wide distribution of abelisaurs in the Late Cretaceous, reasons other than vicariance must be invoked for their apparent absence in the 'middle' Cretaceous of Africa.