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Abelisaurid pedal unguals from the Late Cretaceous of India. VIIo International Symposium on Mesozoic Terrestrial Ecosystems. Asociaci??n Paleontol??gica Argentina
... The distal part of this groove approaches a sigmoid (ventrally arching at its proximal part and dorsally arching at the distal part) groove extending along the lateral surface of the ungual. This set of grooves correspond to the "Y-shaped" system of lateral vascular grooves typical of abelisauroid theropods 93 . On the lateral surface, the area ventral to the lower groove is lateroventrally facing and aligned with the ventral surface of the previous phalanx. ...
... It has the "Y-shaped" system of lateral vascular grooves typical of abelisauroid theropods 93 , including noasaurines 2,6 . The surface between those dorsal and ventral branches is convex, but not protruding as in some abelisaurid unguals 93 . The ungual of digit III is the broadest element in the pes lateromedially, but the shallowest dorsoventrally, with a sharper distal tip and the depth of the proximal margin less than half the proximodistal length of the bone. ...
... Unlike the condition in the former ungual, the pair of lateral grooves does not merge distally. Instead, the ventral one extends along the entirety of the ventral margin of the ungual, whereas the dorsal is restricted to the proximal half of the dorsal margin, as also seen in some abelisauroid unguals 93 . Flanking its proximal articulation, the lateral surface of that phalanx bears the proximal groove ("vg" in Fig. 10d) seen in Mas. ...
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.
... Although medial and lateral bifurcate vascular grooves are observed in several non-abelisauroid taxa (e.g. Russell, 1969;Novas, 1997), the abelisauroid condition shows a more distal separation of two grooves that embrace a prominent bulge (Novas and Bandyopadhyay, 2001;Novas et al., 2004Novas et al., , 2005Novas et al., , 2005Carrano, 2007;Maganuco et al., 2007Maganuco et al., , 2008Maganuco et al., , 2008Brissón Egli et al., 2016;Langer et al., 2019). Furthermore, the pedal ungual phalanx of Abelisauridae indet. ...
... MPCN-PV-69 shares with that of other abelisaurids a proximal ventral fossa instead of a flexor tubercle (e.g. Aucasaurus; Ilokelesia; Skorpiovenator; Novas and Bandyopadhyay, 2001;Novas et al., 2005). This feature was recovered as an Abelisauridae synapomorphy (Rauhut and Carrano, 2016), although it is also observed in Velocisaurus ...
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.
... Pedal phalanges are small, weakly curved, and lack the flexor tubercle. They have single lateral and medial grooves, while two grooves on each side of the phalanx are present in some abelisauroids [16,[41][42][43]. ...
The noasaurid ceratosaur Kiyacursor longipes gen. et sp. nov. is described based on a fragmentary skeleton including cervical vertebra, pectoral girdle, humerus and hind limbs from the Lower Cretaceous (Aptian) Ilek Formation at Shestakovo 1 locality in Western Siberia, Russia. This is the first ceratosaur from the Early Cretaceous of Asia, extending the stratigraphic range of Ceratosauria by 40 Myr on that continent. Kiyacursor shares unique hind limb proportions with Elaphrosaurus and Limusaurus, suggesting improved cursorial ability. These taxa show an ostrich-like specialization of the pes, with a large third metatarsal and greatly reduced second metatarsal. By contrast, all other fast running non-avian theropod dinosaurs have an arctometatarsalian pes, with the third metatarsal strongly reduced proximally. The new taxon lived in the Early Cretaceous ecosystem containing a number of other Jurassic relics, such as stem salamanders, protosuchian and shartegosuchid crocodyliforms, tritylodontid synapsids and docodontan mammaliaforms.
... Ungual phalange specimens: The ungual phalange (BIOPS/TK-AR26; Fig. 4A-D) differs from those of rhynchosaurs Hyperodapedon tikiensis and phytosaurs Parasuchus hislopi which do not have lateral grooves (Novas and Bandyopadhyay 2001). It also differs from the ungual phalange of the phytosaur Pseudopalatus in having a proximoventral flexor tubercle (also see, Zeigler et al. 2003). ...
... Ungual phalange specimens: The ungual phalange (BIOPS/TK-AR26; Fig. 4A-D) differs from those of rhynchosaurs Hyperodapedon tikiensis and phytosaurs Parasuchus hislopi which do not have lateral grooves (Novas and Bandyopadhyay 2001). It also differs from the ungual phalange of the phytosaur Pseudopalatus in having a proximoventral flexor tubercle (also see, Zeigler et al. 2003). ...
Tiki Formation is well known for the presence of rich vertebrate fossil assemblages including archosaurians, cynodonts, xenacanthids, hybodonts and actinopterygians in the Gondwana succession of India. Here, we report indeterminate Sphenodontia and indeterminate Lepidosauromorpha from the Late Triassic Tiki Formation. The presently reported early diverging lepidosauromorphs might have fed on small invertebrates and small vertebrates/insects. The presence of early diverging lepidosauromorphs from the Tiki Formation extends their geographic range from Europe, N. America and S. America to the Indian sub-continent during the Late Triassic Period. Further, the reports of archosauromorph assemblages and the aquatic vertebrates from the Tiki Formation have strengthened the idea of affinities of vertebrate assemblages between Laurasia and Gondwana sub-continents of the Pangea.
... The ventral edge of the proximal articular surface is proximoventrally projecting, forming a rounded lip. The lateral surface of the ungual is well-preserved and shows collateral grooves that are bifurcated proximally but faintly marked; whereas in other abelisaurids such as Aucasaurus, Majungasaurus and some indeterminate taxa these grooves are very deep and well-defined (Novas & Bandyopadhyay 2001;Novas et al. 2004;Maganuco et al. 2008). This phalanx lacks the prominent lateral bump present in the abelisaurids named above. ...
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.
... In the Candeleros Formation, the record corresponds to four indeterminate abelisaurids and one basal brachyrostran, distributed in the central and central-north areas of the Neuqu en province (Calvo et al., 2004;Porfiri et al., 2009;Canale et al., 2016;Cerda and Porfiri, 2019). Five records come from the Huincul Formation, two (an indeterminate abelisaurids, and a basal brachyrostran) come from the Campo de Violante locality in the central-west zone of the Río Negro province (Novas and Bandyopadhyay, 2001;de Valais et al., 2002;Cerroni et al., 2020c), and the remaining three come from the centraleast area of Neuqu en (being all basal brachyrostrans) (Coria and Salgado, 1998;Canale et al., 2009Canale et al., , 2020b. The findings in the Cerro Lisandro, Portezuelo and Plottier formations are scarce and correspond to indeterminate abelisaurids or basal brachyrostrans (Calvo and Gonz alez Riga, 1999;Coria et al., 2006;Ju arez-Valieri et al., 2008). ...
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.
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.
Despite being poorly known from limited skeletal remains as teeth and a few postcranial material, spino-saurid remains have been reported from two different Lower Cretaceous localities in Brazil, with three officially proposed taxa up to now: Angaturama, Irritator and Oxalaia. Here, we report the first record of a spinosaurid pedal ungual from the Itapecuru Formation, Parnaíba Basin, Lower Cretaceous rocks of Maranhão State. The specimen retains a quite flat ventral surface that is proportionally almost two times broader than its proximal depth, which is a feature also found in Spinosaurus. Moreover, size inferences are made for this immature specimen.
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