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Ligabueino andesi (holotype MACN PV-N 42). Digit ?III phalanx in: a lateral view; b dorsal view; c lateroventral view; d proximal view. CLP, collateral ligamental pit; HP, hyperextensor pit; MK, median keel; PDP, proximodorsal process; PVP, proximoventral process. Scale bar 2 mm
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In this note we reassess the position of putative pedal phalanges of some South American noasaurid theropods (Abelisauroidea). Noasaurids were considered as to be distinctive abelisauroids with a peculiar "sickle claw" on the second toe of the foot, convergently developed with that of deinonychosaurians. Among noasaurids, the Argentinean species No...
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Citations
... Carnotaurus' forelimbs, when compared to body size, are even smaller than Tyrannosaurus' (Ruiz et al., 2001(Ruiz et al., , p. 1276. The hand itself is a mess, lacking carpalia (Ruiz et al., 2011), with its four fingers (Bonaparte et al., 1990) not capable of motion (Agnolin & Chiarelli, 2010). Further, Senter (2010) found nerve fiber size so greatly reduced that there was almost no transmission ability. ...
Tyrannosaurus rex is infamous for its large body size and seemingly mismatched forelimbs, which are extremely small relative to body size. Since its first description by Osborn in 1905, the diminutive size of this attribute has fueled an arms race of sorts wherein specialists have advanced numerous theories seeking to prove a seemingly single-track use or non-use for the arms. While the overall debate on the evolutionary processes behind the small limb size are not addressed here, previous functional theories are reviewed within a functionalist perspective. This paper contends that Tyrannosaurus rex would have used its limbs for whatever purposes possible and that selecting one function to the exclusion of others is not a realistic approach to understanding the lifeways of the Tyrant King. Rather, a functionality assessment is suggested and tested using existing theories with the aim of providing a tool to assess future use case theories.
... Essas estruturas associadas com as características dos membros posteriores e vértebras permitem inferir os comportamentos descritos a seguir. Os membros anteriores dos abelissaurídeos foram extremamente reduzidos a partir das regiões distais, perdendo a possibilidade de agarrar (Agnolin & Chiarelli, 2010). Espécies basais, como Eoabelisaurus, apresentam as ungueais das mãos reduzidas (Pol & Rauhut, 2012), enquanto que em outros táxons mais derivados, como Carnotaurus, Majungasaurus e Aucasaurus garridoi, essas estruturas estão ausentes nos dedos I e IV das mãos (Agnolin & Chiarelli, 2010, Burch & Carrano, 2012, Coria et al., 2002. ...
... Os membros anteriores dos abelissaurídeos foram extremamente reduzidos a partir das regiões distais, perdendo a possibilidade de agarrar (Agnolin & Chiarelli, 2010). Espécies basais, como Eoabelisaurus, apresentam as ungueais das mãos reduzidas (Pol & Rauhut, 2012), enquanto que em outros táxons mais derivados, como Carnotaurus, Majungasaurus e Aucasaurus garridoi, essas estruturas estão ausentes nos dedos I e IV das mãos (Agnolin & Chiarelli, 2010, Burch & Carrano, 2012, Coria et al., 2002. Apesar dessa redução dos membros anteriores, a cabeça do úmero em abelissaurídeos era arredondada, sugerindo grande mobilidade na região proximal do braço (Burch, 2017, Gianechini et al., 2015. ...
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.
... The pedal phalanx MPM 21547 resembles Noasauridae in being transversely narrow and dorsoventrally deep, a condition shared with Velocisaurus and Vespersaurus Langer et al., 2019). Further, a well-developed, transversely thick, and posteriorly extended posterodorsal process is also shared with noasaurids, including Noasaurus, Ligabueino, Velocisaurus and Vespersaurus , constituting a synapomorphic feature of Noasauridae (Agnolin & Chiarelli, 2010). However, in the case for the phalanx here described the ventral projection proximally surpasses the level of the dorsal lip, contrasting with known noasaurids in which the projections are sub-equal in proximal extension (e.g., Laevisuchus, Noasaurus; Novas & Bandyopadhyay, 2001, Sampson et al., 2001Agnolin & Chiarelli, 2010;Brissón Egli et al., 2016). ...
... Further, a well-developed, transversely thick, and posteriorly extended posterodorsal process is also shared with noasaurids, including Noasaurus, Ligabueino, Velocisaurus and Vespersaurus , constituting a synapomorphic feature of Noasauridae (Agnolin & Chiarelli, 2010). However, in the case for the phalanx here described the ventral projection proximally surpasses the level of the dorsal lip, contrasting with known noasaurids in which the projections are sub-equal in proximal extension (e.g., Laevisuchus, Noasaurus; Novas & Bandyopadhyay, 2001, Sampson et al., 2001Agnolin & Chiarelli, 2010;Brissón Egli et al., 2016). Noasaurids have been recorded in different Late Cretaceous localities of Gondwana, including India (Novas & Bandyopadhyay, 2001;, Africa (Sampson et al., 2001) and South America (Bonaparte & Powell, 1980;Bonaparte, 1991;Brissón Egli et al., 2016;Langer et al., 2019;Martinelli et al., 2019). ...
The first fossil remains of vertebrates, invertebrates, plants and palynomorphs of the Chorrillo Formation (Austral Basin), about 30km to the SW of the town of El Calafate (Province of Santa Cruz), are described. Fossils include the elasmarian (basal Iguanodontia) Isasicursor santacrucensis gen. et sp. nov., the large titanosaur Nullotitan glaciaris gen. et sp. nov., both large and small Megaraptoridae indet., and fragments of sauropod and theropod eggshells. The list of vertebrates is also composed by the Neognathae Kookne yeutensis gen. et sp. nov., two isolated caudal vertebrae of Mammalia indet., and isolated teeth of a large mosasaur. Remains of fishes, anurans, turtles, and snakes are represented by fragmentary material of low taxonomical value, with the exception of remains belonging to Calyptocephalellidae. On the other hand, a remarkable diversity of terrestrial and freshwater gastropods has been documented, as well as fossil woods and palinological assemblages. The Chorrillo Formation continues south, in the Las Chinas River valley, southern Chile, where it is called Dorotea Formation. Both units share in their lower two thirds abundant materials of titanosaurs, whose remains cease to appear in the upper third, registering only elasmarians (Chorrillo Formation) and hadrosaurs (Dorotea Formation). Above both units there are levels with remains of invertebrates and marine reptiles. It is striking that the dinosaurs of the lower two thirds of the Chorrillo and Dorotea formations are represented by large basal titanosaurs and Megaraptoridae coelurosaurs, being the Saltasaurinae and Aeolosaurinae sauropods and Abelisauridae theropods totally absent. In contrast, these taxa are dominant components in sedimentary units of central and northern Patagonia (e.g., Allen, Los Alamitos, La Colonia formations). Such differences could reflect, in part, a greater antiquity (i.e., late Campanian-early Maastrichtian) for the Chorrillo fossils, or, more probably, different environmental conditions. Thus, knowledge of the biota of the southern tip of Patagonia is expanded, particularly those temporarily close to the K-Pg boundary.
... Noasauridae is a clade of small-sized ceratosaurian abelisauroids, originally proposed by Bonaparte and Powell (1980) based on the Late Cretaceous Argentinean Noasaurus leali (see also Bonaparte, 1991a). Later on, several taxa and records considerably improved the composition of this clade (e.g., Bonaparte, 1991bBonaparte, , 1996Accarie et al., 1995;Sampson et al., 2001;Carrano et al., 2002Carrano et al., , 2011Novas et al., 2004;Sereno et al., 2004;Carrano and Sampson, 2008;Xu et al., 2009;Agnolin and Chiarelli, 2010;Brisson Egli et al., 2016;Rauhut and Carrano, 2016), positioned as the sister-group of Abelisauridae, both comprising the clade Abelisauroidea (e.g., Bonaparte, 1991a;Carrano and Sampson, 2008;Rauhut and Carrano, 2016). Best-documented noasaurids are Masiakasaurus knopfleri from the Upper Cretaceous of Madagascar (Sampson et al., 2001;Carrano et al., 2002Carrano et al., , 2011 and Elaphrosaurus bambergi from the Upper Jurassic of Tanzania (Rauhut et al., 2016), two representative morphotypes of the subclades Noasauridae and Elaphrosaurinae, as recognized in some recent phylogenies (e.g., Rauhut and Carrano, 2016). ...
... Its proximal articulation is much more expanded, both lateromedially and on the extensor-flexor axis, than the distal articulation, and bears a subtle extensor tuber. This expansion is more marked towards the flexor side, as seen in isolated noasaurid manual phalanges 3,84 . The bone is also only about 1.5 times longer than broad at its proximal end, departing from the plesiomorphically more elongated first phalanx of digit I seen in non-abelisauroid taxa, such as Di. ...
... Its biconcave proximal articulation is broader lateromedially than dorsoventrally deep. The bone is less recurved than that of the first digit, not nearly approaching the curvature of the possible second or third manual ungual of N. leali 84 . It bears a clear, low extensor tuber and a single (ventral) "blood" groove, related to the sheath cover, extending along the ventral margin of its lateral surface. ...
... Di. wetherilli 70 . This is also the case for C. nasicornis 79 and the isolated manual phalanges referred to N. leali 84 and Mas. knopfleri 3 . ...
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.
... Abelisaurids has strongly reduced forearms without grasping ability 40 (Fig. 3B). According to Agnolin and Chiarelli 40 , abelisaurs probably also lacked forearm mobility. ...
... However, recent analyses on Majungasaurus musculature suggest that, although much reduced, abelisaurids did not lose full mobility of the forelimb, and may have used it for intraspecific display 41 . Some taxa such as Aucasaurus, Majungasaurus and Carnotaurus may have lost the ungual of the digits I and IV 31,40,42 whereas the ceratosaurid Eoabelisaurus has strongly reduced the manual unguals 12 . The digit IV is fused to the metacarpal in Majungasaurus and Aucasaurus precluding mobility. ...
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 anatomical nomenclature of theropod unguals follows Charig and Milner (1997) and Agnolin and Chiarelli (2010). The phylogenetic framework for Tetanurae followed in this work is based on the results obtained by Rauhut et al. (2016) who performed a phylogenetic analysis on a revised version of the datamatrix of Carrano et al. (2012). ...
... The identification of the claw CSC1-4 as a theropod manual ungual rather than a pedal ungual is based on several features, such as a proximal articular surface that is dorsoventrally tall and shows a marked median keel, an oval transverse cross-section, and a strong curvature (Agnolin and Chiarelli, 2010). The asymmetry in the proximal articular surface (i.e., a dorsoventral ridge slightly offset medially) is used to identify CSC1-4 as a left ungual. ...
... The known manual unguals of non-tetanuran theropods such as those of the ceratosaurians Limusaurus, Masiakasaurus and Noasaurus clearly differ from CSC1-4. Noasaurus differs in that its bizarre claw bears a median ventral ridge (Agnolin and Chiarelli, 2010: fig. 1A), whereas those of Masiakasaurus differ in their lower curvature and the reduction of the flexor tubercle (Carrano et al., 2002: fig. ...
An enlarged theropod manual ungual (CSC1-4) from the Weald facies of Spain is described. The claw was found in the fossil locality of Caña Seca 1, Teruel province, within the El Castellar Formation of early Barremian (Early Cretaceous) in age.
CSC1-4 is morphologically closer to megalosauroids than to any other theropod clade bearing enlarged manual claws and shows the greatest similarity to the manual ungual of digit I of Baryonyx walkeri. Both CS1-4 and this taxon share a particularly enlarged, elongated and transversely wide manual claw. CSC1-4, however, differs from Baryonyx´s ungual in having less curvature, a straight dorsal edge in the proximal part, slightly more width above the grooves than below, and a certain asymmetry, with the lateral face more flattened. Taking into account the paleogeographic and temporal context, these considerations suggest that they are closely related but distinct spinosaurid taxa.
The presence of an enlarged manual claw in spinosaurids has been invoked as an anatomical feature typically associated with scavenging and hunting habits, as well as digging behaviour. The spinosaurid record from the Barremian of the Iberian Peninsula shows that members of this clade favored freshwater environments with some marine influence in this part of Europe.
... These mudrocks were bulk sampled, and wet and dry-sieved to extract the residues, which were then observed under a stereozoom microscope for the collection of the vertebrate microfossils. The terminology used to describe the ungual phalanges follows Novas and Bandyopadhyay (2001), Novas et al. (2005), Agnolin and Chiarelli (2009) and whereas the parameters measured for the current study are shown in Fig. 2A and B. As the unguals are isolated, the lateral side is determined based on higher convexity and prominence of the lateral groove in side views as suggested by Novas and Bandyopadhyay (2001). Diapsida Osborn, 1903(sensu Laurin, 1991 Archosauria Cope, 1869 (sensu Gauthier andPadian, 1985) Dinosauria Owen, 1842 (sensu Padian andMay, 1993) Theropoda Marsh, 1881 Gen. et sp. ...
... indet. Diagnosis: Slender, asymmetric lateromedially compressed unguals are characterized by ventral curvature of the distal end; deep collateral grooves parallel to the ventral margin; large, proximoventrally placed flexor tubercle; dorsoventrally elongated elliptical or oval proximal articular surface; a low but distinct median keel (Agnolin and Chiarelli, 2009;Novas, 2009). ...
... indet. Diagnosis: Robust, nearly symmetric ungual phalanx characterized by gently, ventrally recurved distal part; deep collateral grooves parallel to the ventral margin; small, proximoventrally placed flexor tubercle; lateromedially extended proximal articular surface; prominent median keel with distinct lateral and medial facets (Agnolin and Chiarelli, 2009;Novas, 2009). ...
The Late Triassic Tiki Formation has yielded five isolated nearly complete claws or ungual phalanges from a fossil locality, which are described in detail and compared with other Late Triassic tetrapods. Of these, four ungual phalanges are slender, asymmetric, ventrally recurved, transversely compressed, and contain deep collateral grooves on either side, a low median keel on the proximal articular surface and a prominent proximoventral flexor tubercle showing their high similarity to the theropod dinosaurs. The remaining claw is unlike that of any theropods in terms of high robusticity and near symmetry. However, as in dinosaurs it is ventrally recurved and contains deep lateral grooves, a small flexor tubercle, lateromedially extended proximal articular surface with a distinct median keel and is considered as belonging to an indeterminate dinosaur. Although it is not possible to ascertain whether the unguals belong to a single taxon or multiple taxa, this new find points towards the presence of small dinosaurs in the Late Triassic Tiki fauna.
... Together with the noasaurid synapomorphies listed above, these characters indicate potentially higher support for Noasauridae (excluding Deltadromeus) than currently indicated by Bremer and bootstrap values. The monophyly of Noasaurinae is currently also rather poorly supported, mainly because of the very fragmentary representation of two of the three constituent taxa: the nominal genus of the family, Noasaurus , is only known from a left maxilla, a right quadrate, a right squamosal, a cervical neural arch, a dorsal vertebral body, a cervical rib, the right metatarsal II, and two phalanges, including an ungual (Bonaparte & Powell, 1980; Bonaparte, 1996; Novas, 2009; Agnol ın & Chiarelli, 2010), whereas Velocisaurus is known only from a right lower hindlimb (Bonaparte, 1991b; Novas, 2009 ). Thus, few unambiguous synapomorphies of this clade can currently be established, as most characters are missing in at least one of the taxa. ...
Theropod dinosaurs from the Late Jurassic of Gondwana are still poorly known, with Elaphrosaurus bambergi Janensch, 1920, from the late Kimmeridgian of Tendaguru, Tanzania, being the only taxon represented by more than isolated remains from Africa. Having long been considered a coelurosaurian, more specifically an ornithomimosaur, Elaphrosaurus is currently regarded as a basal ceratosaur. Here, we revise the osteology and phylogenetic position of this important taxon. Elaphrosaurus shows many unusual osteological characters, including extremely elongated and constricted cervical vertebrae, an expansive shoulder girdle with strongly modified forelimbs, a relatively small ilium, and elongate hindlimbs with a very small ascending process of the astragalus that is fused to the tibia. We found this taxon to share many derived characters with noasaurids, such as: strongly elongate cervical and dorsal vertebrae; low, rectangular neural spines in the mid-caudal vertebrae; presence of only an anterior centrodiapophyseal lamina in anterior caudal vertebrae; presence of a wide, U-shaped notch between the glenoid and the anteroventral hook in the coracoid; a laterally flared postacetabular blade of the ilium; a flat anterior side of the distal tibia; and a reduced shaft of metatarsal II. Our analysis placed Elaphrosaurus within a dichotomous Noasauridae as part of a Jurassic subclade, here termed Elaphrosaurinae, that otherwise includes taxa from eastern Asia. These results underscore the long and complex evolutionary history of abelisauroids, which is still only beginning to be understood.
... He also suggested that Velocisaurus was a strongly cursorial form and had non-predatory habits and consequently may be distinguished from Noasauridae by lacking raptorial pedal claws. At that time the available unguals of Noasaurus were erroneously interpreted as belonging to the pes (Agnolin and Chiarelli, 2010). However, Carrano and Sampson (2008) considered that Velocisaurus has no clear autapomorphies and concluded that it was probably a valid taxon based only on its geological and geographical provenance. ...
Abelisauroids are the most abundant theropods in the Cretaceous beds of Patagonia. They are traditionally subdivided into large-sized Abelisauridae and smaller Noasauridae. Here, we describe a new specimen of the small enigmatic abelisauroid Velocisaurus unicus Bonaparte, 1991, which was previously known from a single incomplete specimen from Neuquén City, Neuquén Province, Patagonia. The new material comes from the Santonian Bajo de la Carpa Formation (Late Cretaceous) at the Paso Córdova locality, Río Negro Province. It comprises an almost complete left hind limb and offers novel information about the anatomy of this poorly known abelisauroid. The new material shows that Velocisaurus is remarkable in having a very short, stout, and anteriorly bowed femur, which has a notably subtriangular cross-section at its proximal end. The tibia is long and slender, and the anterior surface of the distal end is anteroposteriorly flat and transversely expanded, with an enlarged surface for the ascending process of the astragalus. The pes has a stout third metatarsal, rod-like metatarsals II and IV, and highly modified phalanges of digit IV. The unique combination of characters of Velocisaurus indicates that this taxon belongs to a still poorly understood radiation of gracile-limbed abelisauroids. The inclusion of Velocisaurus in a comprehensive phylogenetic analysis recovers a monophyletic Noasauridae, but with only very weak support. Detailed analysis of features supporting the inclusion of Velocisaurus within Noasauridae is discussed, and their implications for abelisauroid phylogeny are revisited. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Brissón Egli, F., F. L. Agnolín, and Fernando Novas. 2016. A new specimen of Velocisaurus unicus (Theropoda, Abelisauroidea) from the Paso Córdoba locality (Santonian), Río Negro, Argentina. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1119156.
