No full-text available
To read the full-text of this research,
you can request a copy directly from the author.
A reanalysis of Acrocanthosaurus atokensis, its phylogenetic status, and paleobiogeographic implications, based on a new specimen from Texas
... Carcharodontosaurids are characterized by large, ornamented skulls armed with long, fang-like teeth, large body sizes, and reduced forelimbs (Sereno et al. 1996;Sereno and Brusatte 2008;Canale et al. 2022). They include diverse species from Africa (Stromer 1931;Sereno et al. 1996;Sereno and Brusatte 2008), South America (Coria and Salgado 1995;Novas et al. 2005;Coria and Currie 2006;Motta et al. 2016;Coria et al. 2020;Canale et al. 2022), Europe Ortega et al. 2010;Malafaia et al. 2019), North America (Stovall and Langston 1950;Harris 1998;Eddy and Clarke 2011), and presumably Asia (Brusatte et al. 2010;Chokchaloemwong et al. 2019), with a biochron spanning from Valanginian (or Upper Jurassic if we count Veterupristisaurus from Tanzania; Rauhut, 2011) through early Turonian times. South America yielded remains of six carcharodontosaurid species: Lajasvenator ascheriae (Valanginian; Coria et al. 2020), Tyrannotitan chubutensis (Albian; Novas et al. 2005), the Cenomanian (Garrido, 2010), Giganotosaurus carolinii Communicated by: Rodrigo Temp Müller (Coria and Salgado 1995), Mapusaurus roseae (Coria and Currie 2006), Taurovenator violantei (Motta et al. 2016), and Meraxes gigas (Canale et al. 2022). ...
... The atlas lacks pleurocoels and bears a very wide and deeply concave anterior articular surface for the occipital condyle. Postaxial cervical centra ( Fig. 2C (a-e)) are strongly opisthocoelous, with prominent anterior articular balls which exceed the length of the corresponding vertebral centrum, as usual among carcharodontosaurids (e.g., Acrocanthosaurus, Giganotosaurus; Stovall andLangston 1950, Coria andSalgado 1995;Harris 1998;Coria and Currie 2006;Cuesta et al. 2019). A single large pleurocoel is present and subdivided by an anterodorsally inclined bony strut. ...
... Furthermore, an anterior projection of the neural spine of the subsequent posterior vertebra forms a large, anteriorly extending bony flange which articulates into the above-mentioned concavity. This morphology produces serially imbricated neural spines when the cervicals 3 through 6 are in articulation ( Fig. 2A-D), constituting a bizarre condition also documented in the vertebrae 3 through 5 of Acrocanthosaurus (Harris 1998) and, to a lesser extent, in Allosaurus and Concavenator (Madsen 1976;Cuesta et al. 2019). Related to this, the interspinous ligament scars are present along the basal half of the anterior margin of the spine, which is shared with Acrocanthosaurus (Harris 1998). ...
Carcharodontosaurids were gigantic terrestrial dinosaurs and top predators of dinosaur faunas in Gondwanan landmasses during the “Mid”-Cretaceous Period. Despite their wide geographical and stratigraphical distribution, essential parts of their anatomy are still poorly known. The present contribution aims to describe a new partial skeleton of the carcharodontosaurid Taurovenator violantei, which was previously known only by an isolated postorbital bone coming from Cenomanian–Turonian beds of northern Patagonia, Argentina. The neck of Taurovenator is composed of notably high anterior cervicals, bearing neural spines with expanded, flange-like dorsal tips which are successively imbricated. This condition has been reported previously in the carcharodontosaurid Acrocanthosaurus, but its occurrence in Taurovenator and other members of the clade suggests it may represent a synapomorphy of this theropod family. This unique neck morphology was probably related to strong modifications in musculature and restriction in the range of movements within the neck, but not with the head. The new specimen also affords valuable anatomical information on the forelimb of Patagonian carcharodontosaurids. As in other giganotosaurines, Taurovenator shows strongly reduced forelimbs, particularly the forearm, showing hand elements with elongated non-ungual phalanges, and well-marked articular surfaces and muscular insertions, suggesting highly movable digits. This new specimen of Taurovenator allows us to expand anatomical and morpho-functional discussions about the carcharodontosaurid clade.
... 3A,B, and 4A; Gig), whereas it did not vary across early archosauriforms (Pintore et al. 2022b). An upturned femoral head was discussed as an unambiguous synapomorphy of Carcharodontosauridae, which includes many giants (Harris 1998;Brusatte and Sereno 2008;D'Emic et al. 2012;Canale et al. 2015Canale et al. , 2022 but also some smaller, earlier relatives such as Concavenator and Neovenator (the earliest carcharodontosaurids; Hocknull et al. 2009;Cuesta et al. 2018). This feature was also present in Australovenator (the sister taxa of all carcharodontosaurids) but not in smaller, earlier relatives from other tetanuran clades. ...
... This feature was also present in Australovenator (the sister taxa of all carcharodontosaurids) but not in smaller, earlier relatives from other tetanuran clades. Harris (1998) noted that early nonaverostran theropods and ceratosaurids had a downturned femoral head, whereas abelisaurids and non-carcharodontosaurid tetanurans had a rather horizontal femoral head. However, we observed that the femoral head of all early non-averostran neotheropods and ceratosaurians appeared relatively similar to the rather horizontal femoral head orientation of small-bodied taxa in non-carcharodontosaurid tetanurans (e.g., ornithomimids, therizinosaurids, and dromaeosaurids) instead of downturned (Figs. ...
... 3A,B, 4A, 5, and 6). We explain these observations contrasting with those of Harris (1998) by the inclusion of "miniaturized" theropods (i.e., less than 20 kg) in our dataset. Some of these taxa had even more downturned femoral heads than those of early non-averostran neotheropods and ceratosaurians (Table 1; Figs. ...
Theropods are obligate bipedal dinosaurs that appeared 230 Ma and are still extant as birds. Their history is characterized by extreme variations in body mass, with gigantism evolving convergently between many lineages. However, no quantification of hindlimb functional morphology has shown whether these body mass increases led to similar specializations between distinct lineages. Here we studied femoral shape variation across 41 species of theropods (n = 68 specimens) using a high-density 3D geometric morphometric approach. We demonstrated that the heaviest theropods evolved wider epiphyses and a more distally located fourth trochanter, as previously demonstrated in early archosaurs, along with an upturned femoral head and a mediodistal crest that extended proximally along the shaft. Phylogenetically informed analyses highlighted that these traits evolved convergently within six major theropod lineages, regardless of their maximum body mass. Conversely, the most gracile femora were distinct from the rest of the dataset, which we interpret as a femoral specialization to “miniaturization” evolving close to Avialae (bird lineage). Our results support a gradual evolution of known “avian” features, such as the fusion between lesser and greater trochanters and a reduction of the epiphyseal offset, independent from body mass variations, which may relate to a more “avian” type of locomotion (more knee than hip driven). The distinction between body mass variations and a more “avian” locomotion is represented by a decoupling in the mediodistal crest morphology, whose biomechanical nature should be studied to better understand the importance of its functional role in gigantism, miniaturization, and higher parasagittal abilities.
... Although initially recognized as having affinities to Allosaurus (Stovall and Langston, 1950), subsequent work suggested relationships to tyrannosaurids (Langston, 1974), megalosaurids (Romer, 1956;Tatarinov, 1964), and spinosaurids (Walker, 1964;Romer, 1966;Carroll, 1988). Thanks to important new materials (Harris, 1998;Currie and Carpenter, 2000;Eddy and Clarke, 2011), A. atokensis is now one of the most completely known theropods from Early Cretaceous time, and current consensus is that it represents a basal carcharodontosaurid (e.g., Sereno et al., 1996;Harris, 1998;Rauhut, 2003;Carrano et al., 2012) within the larger clade Allosauroidea. ...
... Although initially recognized as having affinities to Allosaurus (Stovall and Langston, 1950), subsequent work suggested relationships to tyrannosaurids (Langston, 1974), megalosaurids (Romer, 1956;Tatarinov, 1964), and spinosaurids (Walker, 1964;Romer, 1966;Carroll, 1988). Thanks to important new materials (Harris, 1998;Currie and Carpenter, 2000;Eddy and Clarke, 2011), A. atokensis is now one of the most completely known theropods from Early Cretaceous time, and current consensus is that it represents a basal carcharodontosaurid (e.g., Sereno et al., 1996;Harris, 1998;Rauhut, 2003;Carrano et al., 2012) within the larger clade Allosauroidea. ...
... The anteroposterior narrowness of these neural arches corresponds well to those of large-bodied theropods such as Allosaurus (Gilmore, 1920;Madsen, 1976), Acrocanthosaurus (Harris, 1998), Mapusaurus (Coria and Currie, 2006) and Tyrannosaurus (Brochu, 2003). This is unlike the condition in ornithomimosaurs, in which the dorsals exhibit dorsoventrally shorter neural arches with more elongate anteroposterior proportions, as in Archaeornithomimus, Deinocheirus, Dromiceiomimus, Gallimimus, Garudimimus, Pelecanimimus, Struthiomimus, and others (Parks, 1928;Osm olska et al., 1972;Smith and Galton, 1990;Kobayashi and Barsbold, 2005;Lee et al., 2014;Sues and Averianov, 2016;Macdonald and Currie, 2019;Cuesta et al., 2022). ...
... The neural spine of the axis of Maip lacks a transversely wide spine table as observed in tyrannosaurids 44,54 . Nevertheless, the neural spine of Maip is notably low, being slightly lower than those of Allosaurus or Tyrannosaurus but much lower when compared with carcharodontosaurids (such as Acrocanthosaurus or Concavenator 55,56 ). In Maip the postzygapophyses are rounded, being slightly transversely wider than anteroposteriorly long, which seems the condition for Tyrannosaurus 44 . ...
... In Maip the postzygapophyses are rounded, being slightly transversely wider than anteroposteriorly long, which seems the condition for Tyrannosaurus 44 . In contrast, allosauroids such as Allosaurus and carcharodontosaurids (e.g., Acrocanthosaurus, Giganotosaurus) show large postzygapophyses that are notably transversely wider than long 33,43,55 . Furthermore, the orientation of the articular surface of the postzygapophyses is sub-horizontal or slightly upturned in Maip and other theropods such as Allosaurus or Tyrannosaurus 43,44 . ...
... By contrast, in carcharodontosaurids the articular surface of the postzygapophyses are strongly dorsally oriented. The epipophyses of Maip are moderately developed as occurs in many tetanurans 57 ; however, in carcharodontosaurids, the epipophyses are notably developed and strongly dorsolaterally projected; 55,56 . In sum, the axis of Maip shows a unique morphology which could be autapomorphic of this species or common to its group; until new megaraptorid skeletons come to light this cannot be confirmed. ...
Megaraptora is a theropod clade known from former Gondwana landmasses and Asia. Most members of the clade are known from the Early to Late Cretaceous (Barremian–Santonian), with Maastrichtian megaraptorans known only from isolated and poorly informative remains. The aim of the present contribution is to describe a partial skeleton of a megaraptorid from Maastrichtian beds in Santa Cruz Province, Argentina. This new specimen is the most informative megaraptoran known from Maastrichtian age, and is herein described as a new taxon. Phylogenetic analysis nested the new taxon together with other South American megaraptorans in a monophyletic clade, whereas Australian and Asian members constitute successive stem groups. South American forms differ from more basal megaraptorans in several anatomical features and in being much larger and more robustly built.
... Comparisons: These isolated specimens, found in multiple localities, are all identifiable as carcharodontosaurs based on numerous apomorphies. The teeth possess many characters found in the Carcharodontosauria, including transverse enamel undulations, basally inclined interdenticular sulci, and S-shaped mesiodistal profile (Benson, Carrano & Brusatte, 2010;Coria & Currie, 2006;Currie & Azuma, 2006;Currie & Carpenter, 2000;Harris, 1998;Naish, 2011;Novas et al., 2013;Sereno et al., 1996). While tall and moderately recurved, this tooth morphotype lacks the extensive anterior carina, extreme labiolingual compression, and large size observed in carcharodontosaurids such as Mapusaurus, Giganotosaurus, and Carcharodontosaurus (Coria & Currie, 2006;Novas et al., 2013). ...
... While tall and moderately recurved, this tooth morphotype lacks the extensive anterior carina, extreme labiolingual compression, and large size observed in carcharodontosaurids such as Mapusaurus, Giganotosaurus, and Carcharodontosaurus (Coria & Currie, 2006;Novas et al., 2013). It shares a rectilinear, moderately recurved shape and non-angled, rectangular ('cartouche') distal denticles with Acrocanthosaurus, but differs in its smaller size, narrower base, and presence of interdenticular sulci, transverse enamel banding, and apically-restricted mesial carina (Currie & Carpenter, 2000;Harris, 1998). This morphotype shares numerous characters with Neovenator including labiolingually narrow, highly elongate and mildly recurved crowns, low, rectangular denticles, and mesial denticles half the height of the distal denticles (Brusatte, Benson & Hutt, 2008). ...
... Chevron DMNH 2013-07-1990 is assigned to Theropoda due to the presence of paired anterior processes on the base, while a tetanuran affinity is supported by the posterior curvature of the shaft (Rauhut, 2003). Paired anterior and posterior processes are observed across a range of tetanurans including Torvosaurus, Allosaurus, Acrocanthosaurus, Neovenator, Tyrannosaurus, Alioramus, and Daspletosaurus (Brochu, 2003;Brusatte, Benson & Hutt, 2008;Currie & Carpenter, 2000;Harris, 1998). It differs from tyrannosauroids, which possess an enlarged haemal canal, widely spaced and diminutive anterior processes, and straight shaft with a posteriorly expanded and spatulate distal end (Brochu, 2003). ...
While the terrestrial fossil record of the mid-Cretaceous interval (Aptian to Cenomanian) in North America has been poorly studied, the recent focus on fossil localities from the western United States has offered a more detailed picture of vertebrate diversity, ecosystem dynamics and faunal turnover that took place on the western landmass of Laramidia. This is in stark contrast to the terrestrial record from the eastern landmass of Appalachia, where vertebrate fossils are rare and consist mostly of isolated and fragmentary remains. However, a detailed understanding of these fossil communities during this interval is necessary for comparison of the faunal patterns that developed during the opening of the Western Interior Seaway (WIS). The Woodbine Group of Texas is a Cenomanian age (95–100 mya) deposit consisting of shallow marine, deltaic, and terrestrial communities, which were only recently separated from their western counterparts. These deposits have yielded a wealth of vertebrate remains, yet non-avian theropods are still largely unknown. Recently, multiple localities in the Lewisville Formation of the Woodbine Group have yielded new non-avian theropod material, including numerous isolated teeth and postcranial remains. While largely fragmentary, this material is sufficiently diagnostic to identify the following taxa: a large-bodied carcharodontosaur, a mid-sized tyrannosauroid, a large ornithomimosaur, a large dromaeosaurine, a small dromaeosaurid, a small troodontid, and a small coelurosaur. Some of these groups represent the first occurrence for Appalachia and provide a broader understanding of a newly expanded faunal diversity for the Eastern landmass. The Lewisville Formation theropod fauna is similar in taxonomic composition to contemporaneous deposits in Laramidia, confirming that these groups were widespread across the continent prior to extension of the WIS. The Lewisville Formation documents the transitional nature of Cenomanian coastal ecosystems in Texas while providing additional details on the evolution of Appalachian communities shortly after WIS extension.
... 2A-E; Table 1). Based on comparisons with the postcranial axial series of other megaraptorids (Aerosteon riocoloradensis [Sereno et al. 2008], Megaraptor namunhuaiquii [MUCPv 595;Porfiri et al. 2014], Murusraptor barrosaensis [Coria and Currie 2016], Tratayenia rosalesi ) and non-megaraptoran, non-maniraptoriform avetheropod taxa including Allosaurus fragilis (Gilmore 1920;Madsen 1976), Asfaltovenator vialidadi (Rauhut and Pol 2019), Carcharodontosauridae (Acrocanthosaurus atokensis [Stovall and Langston 1950;Harris 1998], Concavenator corcovatus [Cuesta et al. 2019], Lajasvenator ascheriae [Coria et al. 2020], Tyrannotitan chubutensis [Canale et al. 2015]), Metriacanthosauridae (Sinraptor dongi [Currie and Zhao 1993], Sinraptor hepingensis [Gao 1999]), Neovenator salerii (Brusatte et al. 2008), and Tyrannosauroidea (Alioramus altai [Brusatte et al. 2012], Tyrannosaurus rex [Brochu 2003], Xiongguanlong baimoensis [Li et al. 2010]), we identify this vertebra as the 13 th or 14 th presacral (of a presumed total of 23). Therefore, assuming that, as is indicated by the nearly complete presacral series of the juvenile Megaraptor individual MUCPv 595 (Porfiri et al. 2014, megaraptorids possessed ten cervical vertebrae, then UNPSJB-PV 944-3 would correspond to the third or fourth dorsal vertebra. ...
... The neural spine is dorsally incomplete but appears to have been considerably lower than in anterior dorsal vertebrae of metriacanthosaurids (Dong et al. 1983;Currie and Zhao 1993;Gao 1999), Acrocanthosaurus (Stovall and Langston 1950;Harris 1998), Tyrannosaurus rex (Brochu 2003), and Aerosteon (Sereno et al. 2008), more closely resembling the condition in anterior dorsals of Megaraptor (Porfiri et al. 2014). The neural spine of UNPSJB-PV 944-3 is slightly anterodorsally inclined, as in Siats (Zanno and Makovicky 2013) and dorsal vertebra 1 (but not dorsal 4) of Aerosteon, contrasting its posterodorsal orientation in most metriacanthosaurids (Dong et al. 1983;Currie and Zhao 1993), at least some tyrannosauroids (e.g., Brochu 2003; Li et al. 2010), and dorsal 2 of Murusraptor (MCL pers. ...
... Sagittally, a dorsally incomplete prominence arises from the dorsal surface of the vertebra, anterior to the broken base of the neural spine. It may represent the remains of an 'anterior process' or 'accessory neural spine' similar to that observed in mid-caudals of many non-maniraptoriform avetheropods, such as Acrocanthosaurus (Stovall and Langston 1950;Harris 1998;Currie and Carpenter 2000), Allosaurus fragilis (Madsen 1976), Bicentenaria argentina (Novas et al. 2012: fig. 3d, "ls"), Concavenator (Cuesta et al. 2019), Lajasvenator (Coria et al. 2020: fig. ...
We describe two partial postcranial skeletons belonging to the enigmatic theropod dinosaur clade Megaraptoridae from the Upper Cretaceous (lower Cenomanian-upper Turonian) Bajo Barreal Formation of southern Chubut Province, central Patagonia, Argentina. The specimens are assigned to Megaraptoridae due to their possession of multiple anatomical features that are considered synapomorphies of that predatory dinosaur group, such as a greatly enlarged, laterally compressed ungual of manual digit I that possesses asymmetrical lateral and medial vascular grooves. Overlapping elements of the two skeletons are nearly identical in morphology, suggesting that they probably represent the same taxon, a large-bodied theropod that was previously unknown from the early Late Cretaceous of southern South America. The Bajo Barreal specimens constitute the most ancient unquestionable records of Megaraptoridae from that continent, and exhibit particularly strong osteological resemblances to penecontemporaneous megaraptorids from the Winton Formation of Australia. Phylogenetic analysis recovers the unnamed Bajo Barreal taxon as the earliest-diverging South American megaraptorid and the oldest-known representative of this clade that likely attained a body length of at least seven meters and a mass of at least one metric ton. Overall, the balance of the evidence suggests that megaraptorids originated in eastern Gondwana (Australia) during the Early Cretaceous, then subsequently dispersed to western Gondwana (South America) during the mid-Cretaceous, where they attained substantially larger body sizes, ultimately coming to occupy the apex predator niches in their respective habitats.
... Where only the illustrations and descriptions of published works were used, only the references are cited. Theropods we compared Allosaurus material with include the basal theropods: Tawa hallae (GR 241,155,242,243,244) MNHN 1998-13 (Allain, 2002Allain, 2005)), Piatnitzkysaurus floresi (PVL 4073; MACN Pv CH895 (Bonaparte, 1986;Rauhut, 2004)), Eustreptospondylus oxoniensis (OUMNH J.3311 (Sadlier, et al., 2008)), Monolophosaurus jiangi (IVPP 84019 (Zhao & Currie, 1993;Brusatte, Benson & Xu, 2010;Zhao et al., 2010)), and the allosauroids Sinraptor dongi (IVPP 10600 (Currie & Zhao, 1993a)), Sinraptor hepingensis (Gao, 1992), Acrocanthosaurus atokensis (NCSM 14345 (Eddy & Clarke, 2011) and OMNH 10146 (Stovall & Langston, 1950;Harris, 1998;Currie & Carpenter, 2000)); and Carcharodontosaurus saharicus (SGM-Din 1). Additionally we have compared Allosaurus materials to the basal coelurosaurs Tanycolagreus topwilsoni (TPII 2000-09-29), Coelurus fragilis (YPM 1991-1995, 9162 (Carpenter et al., 2005 (Paul & Carpenter, 2010;Carrano, Loewen & Evers, 2018) and material from the CLDQ quarry including: UMNH VP 1251, 3113, 5316, 5326-5328, 5470, 5480, 6317, 6340, 6365, 6400, 6408, 6473, 6475, 6499, 6502, 7190, 7408, 7411, 7794, 7880, 7882, 7884-7885, 7889-7891, 7895, 7898, 7908, 7922, 7926-7930, 7932, 7934, 7937-7938, 7957, 7966, 8102, 8123, 8142, 8151, 8229, 8240-8241, 8355, 8397, 8484, 9103, 9147, 9149, 9162, 9168, 9180, 9191, 9201, 9212, 9323, 9327, 9366, 9376, 9401, 9470, 9473, 9480, 9500, 9502, 9505, 9514, 9709, 10360, 10386, 10779, 11031, 11463, 12231, Terminology We employ traditional, or "Romerian" anatomical and directional terms over veterinary alternatives (Romer, 1956;Wilson, 2006). ...
... The ectopterygoid is well known in Allosaurus fragilis but poorly known in most other basal tetanurans. In Sinraptor dongi (Currie & Zhao, 1993a;Witmer, 1997a) and Acrocanthosaurus (Eddy & Clarke, 2011;Harris, 1998) the pneumatic ectopterygoid recess is larger and more extensively developed than Allosaurus, extending onto the jugal process. In Sinraptor dongi the recess exits through a large foramen medially to contact the jugal anteriorly (Currie & Zhao, 1993a). ...
... The palatine is unknown or undescribed in nearly all allosauroids. In medial view the palatine of Allosaurus jimmadseni does not differ significantly from that of Allosaurus fragilis (Madsen, 1976), Sinraptor dongi (Currie & Zhao, 1993a), and Acrocanthosaurus atokensis (Eddy & Clarke, 2011;Harris, 1998). Laterally, Allosaurus jimmadseni lack the pneumatic palatine recesses (Witmer, 1997a(Witmer, , 1997b on the lateral surface which are present in Sinraptor dongi and Acrocanthosaurus atokensis. ...
Allosaurus is one of the best known theropod dinosaurs from the Jurassic and a crucial taxon in phylogenetic analyses. On the basis of an in-depth, firsthand study of the bulk of Allosaurus specimens housed in North American institutions, we describe here a new theropod dinosaur from the Upper Jurassic Morrison Formation of Western North America, Allosaurus jimmadseni sp. nov., based upon a remarkably complete articulated skeleton and skull and a second specimen with an articulated skull and associated skeleton. The present study also assigns several other specimens to this new species, Allosaurus jimmadseni , which is characterized by a number of autapomorphies present on the dermal skull roof and additional characters present in the postcrania. In particular, whereas the ventral margin of the jugal of Allosaurus fragilis has pronounced sigmoidal convexity, the ventral margin is virtually straight in Allosaurus jimmadseni . The paired nasals of Allosaurus jimmadseni possess bilateral, blade-like crests along the lateral margin, forming a pronounced nasolacrimal crest that is absent in Allosaurus fragilis .
... In dorsal view, the articular is as wide as long, with a depressed and strongly wide glenoid region. The glenoid region is not separated in the lateral and medial glenoid fossae by a sharp ridge, like Allosaurus [58] or Sinraptor [44]. However, this interglenoid ridge is also greatly reduced in Mapusaurus and low in Acorcanthosaurus [41]. ...
... Moreover, the camerate condition is visible in Siamraptor due to the presence of cavities consisting of several large chambers that are not further subdivided [62]. This type of internal pneumatic cavities is present in most tetanurans but is distinct from those camellate-type vertebrae of derived carcharodontosaurids and other carcharodontosaurians [45,58]. Moreover, derived carcharodontosaurids like Tyrannotitan (MPEF-PV 1157) and Giganotosaurus (MUCP-Ch 1) have a strong opisthocoelic condition in the cervical vertebrae. ...
... Therefore, Siamraptor shows a primitive condition due to the short epipophyses in its cervical vertebrae, a symplesiomorphy also observed in Allosaurus. Although not complete, Siamraptor also shows a primitive condition in the dorsal neural spine of the dorsal vertebra due to its vertical orientation, unlike the anteriorly-inclined neural spine in some allosauroids [58]. ...
The isolated fossil remains of an allosauroid theropod from the Lower Cretaceous Khok Kruat Formation of Khorat, Thailand, are described in this study. Detailed observations support the establishment of a new allosauroid, Siamraptor suwati gen. et sp. nov. This new taxon is based on a composite cranial and postcranial skeleton comprising premaxilla, maxilla, jugal, surangular, prearticular, articular, vertebrae, manual ungual, ischium, tibia, and pedal phalanx. It is distinguished from other allosauroids by characters such as a jugal with straight ventral margin and dorsoventrally deep anterior process below the orbit, a surangular with a deep oval concavity at the posterior end of the lateral shelf and four posterior surangular foramina, a long and narrow groove along the suture between the surangular and the prearticular, an articular with a foramen at the notch of the suture with the prearticular, an anterior cervical vertebra with a pneumatic foramen (so-called ‘pleurocoel’) excavating parapophysis, and cervical and posterior dorsal vertebrae penetrated by a pair of small foramina bilaterally at the base of the neural spine. The presence of a huge number of camerae and pneumatopores in cranial and axial elements reveals a remarkable skeletal pneumatic system in this new taxon. Moreover, the phylogenetic analyses revealed that Siamraptor is a basal taxon of Carcharodontosauria, involving a new sight of the paleobiogeographical context of this group. Siamraptor is the best preserved carcharodontosaurian theropod in Southeast Asia, and it sheds new light on the early evolutionary history of Carcharodontosauria.
... 55-0; SI) ( Fig. 2). Murusraptor differs from basal tetanurans (Allosaurus, Sinraptor, Acrocanthosaurus; Madsen, 1976;Currie and Zhao, 1993;Harris 1998) in that the latter bear prominent lacrimal protuberances. The absence of hornlets is a feature regarded by Holtz (1998) as possibly diagnostic for Coelurosauria, as observed in Compsognathus, Juravenator, and Ornitholestes, among others. ...
... This morphology is shared with tyrannosauroids (e.g., Alioramus, Albertosaurus, Daspletosaurus, Dilong, Gorgosaurus, Guanlong, Tarbosaurus, Tyrannosaurus [in both juvenile and adult specimens of the two later genera]; Carr, 1999;Currie, 2003;Brochu, 2003;Xu et al., 2004Xu et al., , 2006Tsuihiji et al., 2011;Bever et al., 2013). On the contrary, basal tetanurans (e.g., Acrocanthosaurus, Allosaurus, Carcharodontosaurus, Giganotosaurus, Sauroniops, Sinraptor, Shaochilong; Madsen, 1976;Coria and Salgado, 1995;Harris, 1998;Azuma and Currie, 2000;Cau et al., 2012) and basal coelurosaurs (e.g., Compsognathus, Ornitholestes, Zuolong; Carpenter et al., 2005;Peyer, 2006;Choiniere et al., 2010) lack this conformation and show a simple supratemporal fossae. Also notable is the presence of a transversely narrow median parietal crest. ...
... Contrary to this statement, Murusraptor shows a well-defined sagittal crest, resulting from the encounter of both parietals along skull mid-line, forming a sharp longitudinal crest contiguous with the mid-line crest present on paired frontals. This condition clearly distinguishes megaraptorids (Murusraptor, Megaraptor; Porfiri et al., 2014) from basal tetanurans (e.g., Allosaurus, Sinraptor, Acrocanthosaurus, Carcharodontosaurus, Giganotosaurus; Madsen, 1976;Coria and Salgado, 1995;Sereno and Brusatte, 2008;Harris, 1998;Zhao and Currie, 2000) in which the dorsal surface of the parietals is transversely wide and flattened, lacking a sagittal crest. Parietals without a sharp longitudinal crest is plesiomorphycally retained among Coelurosauria as it is seen in compsognathids, Guanlong and Dilong in which the dorsal surface of parietals is flattened. ...
Phylogenetic relationships of megaraptorid theropods are under intense debate. Some authors interpret them as archaic allosauroids that survived up to Late Cretaceous, whereas others consider megaraptorids as basal tyrannosauroids. The recently described Patagonian taxon Murusraptor barrosaensis offers novel information on skull, axial and hind limb anatomy, all of which may help in elucidating the phylogenetic affinities of megaraptorids as a whole. Murusraptor is particularly similar to juvenile specimens of tyrannosaurids; both share: 1) lacrimal with a long anterior process; 2) corneal process and; 3) lateral pneumatic fenestra; 4) square and dorsoventrally low frontals; 5) parietals with well-developed sagittal and nuchal crests, among other features. The current study lends further support to the hypothesis that megaraptorans are basal members of Coelurosauria (supported by 20 synapomophies), with strongest affiliation with Tyrannosauroidea (supported by >20 synapomorphies).
... The ventrolateral body expands into rostral and caudal portions, the straight lateral margin of which serves for the articulation with the maxilla and, probably, the jugal. The short rostral prong (= maxillary process [67]) is completely preserved, but the caudal part of the ventrolateral body is partially covered by matrix and difficult to interpret. As preserved, it is composed of a short and slightly laterally expanding jugal process [67]. ...
... The short rostral prong (= maxillary process [67]) is completely preserved, but the caudal part of the ventrolateral body is partially covered by matrix and difficult to interpret. As preserved, it is composed of a short and slightly laterally expanding jugal process [67]. The entire length of the jugal process, as well that of a second medial prong ("peg" of Prieto-Márquez & Norell [65]) cannot be confirmed. ...
... The entire length of the jugal process, as well that of a second medial prong ("peg" of Prieto-Márquez & Norell [65]) cannot be confirmed. On the lateral surface, the jugal process is continuous with a ridge that extends rostrally forming the lateroventral margin of the caudal portion of the vomeropterygoid process [67]. This crest rises laterally relative to the depressed muscular fossa, caudodorsally [68], and the maxillary process, rostroventraly. ...
Sauropodomorphs are the most abundant and diverse clade of Triassic dinosaurs, but the taxonomy of their earliest (Carnian) representatives is still poorly understood. One such taxon is Pampadromaeus barberenai, represented by a nearly complete disarticulated skeleton recovered from the upper part of the Santa Maria Formation of Rio Grande do Sul, Brazil. Here, the osteology of Pam. barberenai is fully described for the first time. Detailed comparisons with other Carnian sauropodomorphs reveal a unique anatomy, corroborating its status as a valid species. Potential autapomorphies of Pam. barberenai can be seen in the articulation of the sacral zygapophyses, the length of the pectoral epipodium, the shape of the distal articulation of the femur and the proximal articulation of metatarsal 1. A novel phylogenetic study shows that relationships among the Carnian sauropodomorphs are poorly constrained, possibly because they belong to a “zone of variability”, where homoplasy abounds. Yet, there is some evidence that Pam. barberenai may nest within Saturnaliidae, along with Saturnalia tupiniquim and Chromogisaurus novasi, which represents the sister group to the larger sauropodomorphs, i.e. Bagualosauria.
... Anterior caudal neural spines that are mediolaterally narrow and anteroposteriorly short, restricted to the posterior part of the neural arch and extend to or partially overhang the posterior articular surface, are present in many tetanuran theropods, including megalosauroids [70,74], allosauroids [66,75] and coelurosaurs [72,76]. This differs from the spinosaurid condition in which the anteriormost caudals support the distal part of the sail and have robust neural spines that approach the anteroposterior length of their respective centra [77]. ...
... As a consequence of the posterior position of the neural spine, many of the aforementioned taxa also have postzygapophyses that are situated at the base of the neural spine and overhang the posterior articular surface [72]. In most theropods, the anteriormost caudals have postzygapophyseal facets that are angled at greater than 408 from the horizontal [56,78,79]; however, a few taxa-including LRF 3310-3312-have postzygapophyseal facets that are angled more shallowly, or lie essentially horizontally [72,75,80,81]. ...
... An internal structure of the vertebrae consisting of a large number of irregularly shaped chambers delimited by thin septa is termed camellate [86] and is present in some ceratosaurs [87], carcharodontosaurids [75], megaraptorids [51,62], Neovenator [66] and coelurosaurs [88]. However, some [megaraptorid] theropods may also present vertebrae with the plesiomorphic condition of a smaller number of larger chambers with thicker septa, defined as a camerate structure and present predominantly in basal tetanurans [86,89]. ...
The limited fossil record of Australian Cretaceous theropods is dominated by megaraptorids, reported from associated and isolated material from the Early Cretaceous of Victoria and the ‘Mid’-Cretaceous of central-north New South Wales and central Queensland. Here, we report on new postcranial theropod material from the early Late Cretaceous Griman Creek Formation at Lightning Ridge. Among this new material is an associated set consisting of two anterior caudal vertebrae and a pubic peduncle of the ilium, to which a morphologically similar partial vertebral centra from a separate locality is tentatively referred. These elements display a combination of characteristics that are present in megaraptorid and carcharodontosaurid theropods, including camellate internal organization of the vertebral centra, ventrally keeled anterior caudal centra and a pubic peduncle of the ilium with a ventral surface approximately twice as long anteroposteriorly as mediolaterally wide. Unfortunately, a lack of unambiguous synapomorphies precludes accurate taxonomic placement; however, avetheropodan affinities are inferred. This new material represents the second instance of a medium-sized theropod from this interval, and only the third known example of associated preservation in an Australian theropod. Additional isolated theropod material is also described, including an avetheropodan femoral head that shows similarities to Allosaurus and Australovenator, and a mid-caudal vertebral centrum bearing pneumatic foraminae and extensive camellae that is referrable to Megaraptora and represents the first axial skeletal element of a megaraptorid described from Lightning Ridge.
... The clade is well-represented by a considerable diversity of taxa and the cranial region is known from several specimens. Among Carcharodontosauridae, Acrocanthosaurus atokensis Stovall and Langston, 1950 has the most complete and well-described skull (Harris, 1998;Currie and Carpenter, 2000;Eddy and Clarke, 2011). Other taxa of this group, such as Giganotosaurus carolinii Coria and Salgado, 1995, Mapusaurus roseae Coria and Currie, 2006and Carcharodontosaurus saharicus (Deperet and Savornin, 1925 have preserved informative cranial remains, although they have not been as thoroughly described at present. ...
... (1) the vomeropterygoid ramus of the palatine, in articulation with the posterior part of the vomer, and (2) the vomeropalatine ramus of the pterygoid. The palatine preserves a pneumatic recess in the ventral part of the vomeropterygoid ramus on the dorsal surface of the palatine, as in Acrocanthosaurus (Harris, 1998), Sinraptor , Allosaurus and Neovenator , that is a feature of allosauroids. This ramus is anteroposteriorly broad in the dorsal region and shows a wide flange in its anteroventral edge, bordering the internal naris dorsally. ...
... The attachment surface is posteriorly oriented, as in allosauroids and some coelurosaurians. Anterior to the retroarticular process, a welldeveloped spine is present in carcharodontosaurids (Harris, 1998;Eddy and Clarke, 2011), but in Concavenator it is broken. ...
Concavenator corcovatus is a carcharodontosaurid dinosaur represented by an almost complete and articulated skeleton from the ‘Las Hoyas’ fossil site (Lower Cretaceous, Spain). The skull of Concavenator is almost complete, missing only the anteriormost and posteriormost regions. Here, a review of the cranial anatomy of Concavenator has been carried out to test its phylogenetic relationships. This description provides a detailed revision of the cranial anatomy of carcharodontosaurids, which is relevant to their general phylogenetic relationships. The results show that the skull of Concavenator has several carcharodontosaurid synapomorphies such as: (1) a lacrimal-postorbital contact, (2) a well-developed postorbital boss, (3) anteroventrally oriented postorbital ventral process, (4) an intraorbital process in the postorbital, (5) rostrally projected roughness in the dorsal surface of the postorbital, (6) a notch in the ascending ramus of the maxilla, (7) a sulcus on the anterior margin of the lacrimal ventral ramus, (8) curved dorsal surface of the lacrimal, and (9) fused frontal-parietal contact. Finally, Concavenator has three cranial autapomorphies: (1) connection between the different recesses on the lateral surface of the nasal, (2) elongated and acuminate posterior narial fossa, and (3) a rounded morphology of the ventral surface of the postorbital boss. In addition, anatomical comparison has enabled to create a complete 3D reconstruction of the skull of Concavenator.
... Their ventral surfaces are anteroposteriorly concave but smoothly transversely convex, with no midline ridges or fossae (Figs. 3, 4A and 5A). The proportionally short, tall posterior dorsal centra of Tratayenia resemble those of other megaraptorids (e.g., Aerosteon, Megaraptor, Murusraptor) and many other large-bodied non-avian tetanuran theropods [e.g., Acrocanthosaurus atokensis (Harris, 1998), Allosaurus fragilis (Gilmore, 1920;Madsen, 1976), Baryonyx walkeri (Charig and Milner, 1997), Concavenator corcovatus (Ortega et al., 2010), Neovenator salerii (Brusatte et al., 2008), Siats meekerorum (Zanno and Makovicky, 2013), Sinraptor dongi (Currie and Zhao, 1993), Tyrannosaurus rex (Brochu, 2003), Tyrannotitan chubutensis (Canale et al., 2015), Xiongguanlong baimoensis (Li et al., 2010)] but differ markedly from the anteroposteriorly elongate centra of Gualicho shinyae (Apesteguía et al., 2016:fig. 2) and Spinosaurus aegyptiacus (Stromer, 1915;Ibrahim et al., 2014). ...
... Among nonmaniraptoriform Tetanurae, pleurocoels divided by septa are also present in dorsal vertebrae of Siats (Zanno and Makovicky, 2013:fig. 2c) and the carcharodontosaurids Acrocanthosaurus (Harris, 1998), Giganotosaurus carolinii and Mapusaurus roseae (Coria and Currie, 2006), and Tyrannotitan Canale et al., 2015). Nevertheless, there is no septum within the pleurocoel of dorsal 14 of Tratayenia, although this could potentially be attributable to taphonomic damage. ...
... 8b, 16c). The posteriormost dorsal neural spines are also inclined anteriorly in the allosauroids Acrocanthosaurus (Harris, 1998), Allosaurus (Madsen, 1976), Sinraptor (Currie and Zhao, 1993), and Tyrannotitan (Canale et al., 2015), and in the tyrannosaurid Tyrannosaurus (Brochu, 2003), but are strongly posteriorly inclined in the spinosaurid Baryonyx (Charig and Milner, 1997). As in many theropods, the anterior and posterior faces of the neural spines exhibit rugosities that mark the attachment of interspinous ligaments, and spinopostzygapophyseal laminae are prominent on the posterolateral margins of the neural spine of dorsal 11. ...
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.
... The anterior caudal centrum IPS137683 is characteristic for its apparent simplicity, especially because of the absence of pleurocoels and almost flat ventral surface. The overall morphology of IPS137683, this is an amphy-platycoelus, hourglass-shaped centrum with slightly offset sub-circular articular facets, resemble the anterior caudal elements of several medium to large size theropods, like abelisaurids (Méndez 2014), allosaurids like Allosaurus (Madsen 1976;Britt 1991;Rauhut 1999;Chure 2000), and carcharodontosaurids like Acrocanthosaurus (Harris 1998). ...
... As a final observation, it is worth noting that Acrocanthosaurus atokensis was described as having an 'accessory transversal process' that can be traced along the middle caudal series (Harris 1998). Despite the nature of such feature is not explained in the original study, the location of this feature in the 29 th caudal vertebra (SMU 74646K2; see Harris 1998: fig. ...
... The three well-preserved caudals have conspicuous, wide transverse processes and must be from the middle of the tail. Transverse processes can go far back in caudals of carcharodontosauridsat least 30 in Acrocanthosaurus (Harris, 1998) e but the sizes of the transverse processes and the dimensions of the central suggest that the caudals of MLL-Pv-005 are probably from the region of the 15th to 20th caudals. Presumably the caudals between the sacrum and this section were present when the animal was buried because their alignment follows a natural curve from the hips that would be appropriate for a typical death pose with the tail curved forwards dorsal to the hips. ...
... The neural spine inclines dorsoposteriorly so that the distal (dorsal) end is positioned above the front of the succeeding vertebra. The midline ridge of the neural spine extends forward until it rises into a small but distinct spinous process (accessory neural spine) as in Acrocanthosaurus (Stovall and Langston, 1950;Harris, 1998;Currie and Carpenter, 2000), Allosaurus (Gilmore, 1920), Dubreuillosaurus (Allain, 2005;Apesteguía et al., 2016;Britt, 1991;Broom, 1904;Brusatte et al., 2008Brusatte et al., , 2009Brusatte and Sereno, 2007;Buffetaut et al., 2009), Mapusaurus (Coria andCurrie, 2006), Sinosauropteryx (Currie and Chen, 2001) and a few other theropods. However, accessory neural spines have been reported in rauisuchians (Franca et al., 2011) and probably have little taxonomic utility. ...
A new carcharodontosaurid taxon, Lajasvenator ascheriae gen. et sp. nov. is described. The new taxon is based on two specimens: MLL-PV-Pv-005 is a partial skeleton represented by a portion of the snout, partially articulated presacral vertebral series, four articulated caudal vertebra and fragments of the pelvic girdle; MLL-PV-Pv-007 includes the anterior ends of both dentaries, a quadratojugal, and fragments of cervical vertebrae, ribs and a possible tarsal bone. Lajasvenator is unique in having anterior projections on cervical prezygapophyses, lip-like crests on the lateral surfaces of cervical postzygapophyses, and bilobed anterior processes on cervical ribs. Lajasvenator material was collected from the terrestrial sandstones of the Valanginian Mulichinco Formation. It is the oldest carcharodontosaurid record from South America. This medium sized theropod was found associated with remains of the dicraeosaurid sauropod Pilmatueia, indeterminate diplodocid remains, and a yet unidentified iguanodontian-like ornithopod.
... 18), are quite rounded, in stark contrast to the rather pointed process of NMV P252700 ( Fig. 2A-D). Cervical ribs from the carcharodontosaurid Acrocanthosaurus atokensis are preserved in at least two exemplars (Harris, 1998;Currie and Carpenter, 2000). The posterior cervical rib described by Currie and Carpenter (2000: fig. ...
... 5A) is similar overall to NMV P252700, although the anterolateral process in this rib does not project beyond the margins of the bases of the tuberculum and capitulum. By contrast, all of the cervical ribs described and illustrated by Harris (1998) can be distinguished from NMV P252700 (Fig. 2E, F) by the more acute angle between the tuberculum and the capitulum, and the resultant position of the anterolateral process ventral to both, rather than between them, in the dorsoventral plane. The cervical ribs of Concavenator corcovatus, in lateral view at least, appear superficially similar to NMV P252700 despite the fact that most of them have substantially longer anterolateral processes (Ortega et al., 2010;Cuesta et al., 2019). ...
Megaraptorid theropods thrived in South America and Australia during the mid-Cretaceous. Their Australian record is currently limited to the upper Barremian–lower Aptian upper Strzelecki Group and the upper Aptian–lower Albian Eumeralla Formation of Victoria, the Cenomanian Griman Creek Formation of New South Wales, and the Cenomanian–lowermost Turonian Winton Formation of Queensland. The latter has produced Australovenator wintonensis, the stratigraphically youngest and most complete Australian megaraptorid. The Eric the Red West (ETRW) site on Cape Otway, Victoria (Eumeralla Formation; lower Albian), has yielded two teeth, two manual unguals, and a right astragalus that are almost identical to the corresponding elements in Australovenator. Herein, we classify these as Megaraptoridae cf. Australovenator wintonensis. We also reappraise the ‘spinosaurid’ cervical vertebra from ETRW and suggest that it pertains to Megaraptoridae. Three other theropod elements from ETRW—a cervical rib (preserving a bite mark), a caudal vertebra, and a non-ungual manual phalanx—are also described, although it is not possible to determine their phylogenetic position more precisely than Tetanurae (non-Maniraptoriformes). All elements were found in a fluvial deposit, associated with isolated bones of other theropods, ornithopods, and turtles, amongst others; consequently, no two can be unequivocally assigned to the same theropod individual. The new specimens from ETRW demonstrate that a megaraptorid theropod morphologically similar to Australovenator lived during the late Early Cretaceous in Victoria, at a higher paleolatitude than its northern counterpart. Moreover, they attest to the success of megaraptorids in late Barremian–early Turonian faunas throughout eastern Australia.
... (3) the ventral margin of the proximal articular surface of the manual phalanx I-1 is concave ); (4) manual ungual I-2 is strongly transversely compressed, being oval with a distinct dorsoventral axis in proximal view* (Megaraptora synapomorphy) (Novas 1998); (5) tibia lateral condyle position in the proximal end at its posterior margin is placed well posteriorly to the level of the posterior edge of the medial condyle* (Novas et al. 2013); (6) tibia lateral condyle of the proximal end curves ventrally as a pointed process* ); (7) tibial median prominence in the anterior surface of the distal end is present* (Novas et al. 2013); (8) tibia length is more than 12 times its anteroposterior width at mid-length* (Coelurosauria synapomorphy) (Novas et al. 2013); (9) tibia flattened anteriorly at mid-length, usually with vertical ridges anterolaterally and anteromedially; (10) tibia facet for the reception of the ascending process of the astragalus at the distal end is more or less flat* (Coelurosauria synapomorphy) (Rauhut 2003;Benson et al. 2010;Novas et al. 2013); (11) the height of the ascending process of the astragalus is more than 0.5 times the width of the astragalar body* (Harris, 1998;Novas et al., 2013); (12) transverse width of ascending process of astragalus is occupying total width of anterior surface of distal tibia* (Rauhut 2003); (13) distinct anterior development of the lateral condyle of the astragalar body is present, strong inflexion of the anterior margin of the astragalar body in distal view* (Coelurosauria synapomorphy) (Novas et al. 2013); (14) astragalus with an anteroproximal extension is present* (Megaraptora synapomorphy) ); (15) atragalus ascending process is offset from distal condyles by a pronounced groove* (Coelurosauria synapomorphy) (Holtz et al. 2004); (16) calcaneum, shape in lateral or medial view is strongly asymmetric, with a right angle at the posterior border* (Coelurosauria synapomorphy) (Novas et al. 2013); and (17) the pedal ungual is flattened ventrally (shared with Australovenator). ...
... Vayuraptor nongbualamphuensis is identified as Coeluro sauria by the following characters: (1) tibia lateral condyle position in the proximal end at its posterior margin is placed well posteriorly to the level of the posterior edge of the medial condyle* (Novas et al. 2013); (2) tibial median prominence in the anterior surface of the distal end is present* (Novas et al. 2013); (3) tibia length is more than 12 times its anteroposterior width at mid-length* (Novas et al. 2013); (4) tibia is flattened anteriorly at mid-length, usually with vertical ridges anterolaterally and anteromedially; (5) tibia facet for the reception of the ascending process of the astragalus at the distal end is more or less flat* (Rauhut 2003;Benson et al. 2010;Novas et al. 2013); (6) astragalus with a prominent anteroproximal extension is present* ); (7) astragalus distinct anterior development of the lateral condyle of the astragalar body is present and there is a strong inflexion in the anterior margin of the astragalar body in distal view* (Novas et al. 2013); (8) astragalus ascending process is offset from distal condyles by a pronounced groove* (Holtz et al. 2004); (9) transverse width of the ascending process of the astragalus is occupying total width of anterior surface of distal tibia* (Rauhut 2003); (10) the height of the ascending process of the astragalus is more than 0.5 times the width of the astragalar body* (Harris 1998;Novas et al. 2013); (11) fibular facet of the ascending process of the astragalus reduced and laterally oriented (Novas et al. 2013); (12) calcaneum, shape in lateral or medial view is strongly asymmetric, with a right angle on the posterior border* (Novas et al. 2013). ...
Megaraptora is a clade of mid to large-sized theropods that are long-snouted, large-clawed, highly pneumatized, and have long and gracile metatarsals. The basal member was reported from the Barremian of Japan. A more derived clade, the Megaraptoridae, is known from the Cenomanian to Santonian of Gondwana. Here two new basal coelurosaurs from the Lower Cretaceous Sao Khua Formation of Thailand are described and named as Phuwiangvenator yaemniyomi gen. et sp. nov. and Vayuraptor nongbualamphuensis gen. et sp. nov. Phuwiangvenator is a megaraptoran coelurosaur and diagnosed by the ventrally flat sacral vertebrae with sulci in the anterior and posterior region of the centra and the anterior rim of metatarsal IV sloping proximolaterally to distomedially and being much lower than that of metatarsal III anteriorly. Vayuraptor is a basal coelurosaur and diagnosed by its astragalus which has two horizontal grooves, two fossae at the base of the ascending process, the ascending process being straight laterally and straight and parallel medially with the medial rim sloping to the tip laterally, and a long and slender astragalar ascending process. Although the position of the basal coelurosaur Vayuraptor remains unclear and must await further discovery, megaraptoran affinities are likely. The Early Cretaceous megaraptoran fossil record has been recovered from the Barremian to Aptian of Asia. All Asian megaraptorans might be a monophyletic clade or a paraphyletic series relative to the Megaraptoridae. Several specimens have been reported from the Aptian to mid-Cretaceous of Australia, and one report from the Albian of South America. These fossils show a high diversity of the Early Cretaceous megaraptorans and a wide distribution during that time. The clade then became more provincial in the Late Cretaceous.
... These posterior vertebrae have elongated neurapophyses, five times the height of the centrum (Ortega et al., 2010) and twice the height of the 10th spine. Hypertrophied neurapophyses are relatively common within carcharodontosaurids. Acrocanthosaurus (Harris, 1998), Tyrannotitan, Mapusaurus and Giganotosaurus have spines taller than twice the vertebral centrum height in their whole dorsal series. In Concavenator, in contrast, only the last two dorsal vertebrae bear neural spines five times longer than the centrum height. ...
... Concavenator has pleurocoels only present until the middle dorsal vertebral series and not in all the dorsal series, like in basal allosauroids and unlike other members of Carcharodontosauria (Harris, 1998). ...
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.
... Allosaurus fragilis Marsh, 1877, presents a complete pelvic girdle and hind limbs from several individuals (Madsen, 1976). Several individuals of Acrocanthosaurus atokensis preserve ischia, pubes, femora, incomplete tibia, and an almost complete pes (Harris, 1998;Currie and Carpenter, 2000). Mapusaurus roseae is represented by a complete ilium and ischium, a partial pubis, and an almost complete hind limb, including the pes (Coria and Currie, 2006). ...
... Within Allosauroidea, metriacanthosaurids, except Sinraptor (Curie and Zhao, 1993), present an expanded anterior process on the ischial end. An anterior process is also present in Neovenator , Acrocanthosaurus (Harris, 1998), and Concavenator, but it is absent in Allosaurus (Madsen, 1976), Giganotosaurus, and Mapusaurus, which have a spatula-shaped anterior end. However, the ischial distal end in these taxa has a boot shape that differs from those of metriacanthosaurids. ...
The holotype of Concavenator corcovatus (MCCM-LH 6666) is a carcharodontosaurid skeleton from the Lower Cretaceous Las Hoyas fossil site in Spain. The appendicular skeleton of Concavenator is the most complete for any Carcharodontosauridae, with only a few regions absent. We describe the limb osteology of Concavenator and carry out an anatomical comparison with other theropods. The results show that Concavenator presents several allosauroid and carcharodontosaurid synapomorphies. Concavenator shares with other allosauroids symmetric glenoid rims of the scapulacoracoid, a canted orientation of the proximal and distal humeral ends, an anterior position of the humeral condyle on the distal end, a long manus relative to the forearm, curved ungual phalanges, a posteriorly broad brevis fossa in the ilium, a reduced ischial tuberosity, a posterior flange on the iliac peduncle of the ischium, and a reduced distal tubercle in the ischium. A concavity on the middle of the proximomedial surface of the humeral head is postulated as a new synapomorphy of carcharodontosaurids. We propose some autapomorphies of Concavenator regarding the length of the phalanges of digit III, the height of the olecranon process relative to ulna length, the proportions of the deltopectoral crest, and the projection of the preacetabular hook in the ilium. The osteological description of the complete appendicular skeleton of Concavenator provides some novelties in the limbs of carcharodontosaurids and is relevant to understanding its general phylogenetic relationships.
SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP
Citation for this article: E. Cuesta, E., F. Ortega, and J. L. Sanz. 2018. Appendicular osteology of Concavenator corcovatus (Theropoda: Carcharodontosauridae) from the Lower Cretaceous of Spain. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2018.1485153.
... The broader structure is more analogous to that of the American bison, serving as attachments for large muscles and ligaments, suggesting a hump-like structure rather than a sail [Bailey, 1997]. Additionally, the expansive area for inter-and supraspinous ligament attachment on the neural spines of Acrocanthosaurus indicates that this taxon did not possess a sail like Dimetrodon, but instead developed musclature on its back, resembling the structure of bison [Harris, 1998]. In contrast, while Bailey (1997) speculated that Spinosaurus may have had a bison-like hump, Ibrahim et al. (2014) argued that its neural spines lacked the well-developed ligament attachment sites seen in Acrocanthosaurus, suggesting that the elongated neural spines of Spinosaurus were less likely to support a muscle-covered hump, despite their broader shape. ...
Deinocheirus is a bizarre and unique theropod dinosaur. The holotype of Deinocheirus was discovered in 1976, but its characteristics and phylogenetic position remained largely enigmatic due to the scarcity of fossil material. This changed in 2014 when Lee et al. described two additional specimens, providing a deeper insight into this mysterious creature. Notably, the smaller specimen MPC-D 100/128 preserved a relatively complete dorsal vertebra with hyperelongated neural spines, reaching up to 8.5 times the height of the corresponding centra. This suggests that Deinocheirus possessed a raised dorsal sail or hump-like structure. Elongated neural spines have evolved multiple times in dinosaurs, including in ornithopods of ornithischians as well as theropods and sauropods of saurischians, with various hypothesized functions such as thermoregulation, fat storage, or sexual display. However, previous research on the neural spines of Deinocheirus has been limited to brief description, lacking detailed analysis and leaving the morphology and function of these dorsal structures poorly understood. To better understand the possible dorsal structure of Deinocheirus and its ecological role, this study examines the dorsal neural spines of Deinocheirus and 26 other dinosaurs. Through measurement and comparative analyses, we categorize the height and width of neural spines into different categories. Our comparison reveal that the neural spines of Deinocheirus are most similar to those of Spinosaurus and Ouranosaurus, with a height ratios exceeding 7 and overall morphology closer to the latter. Additionally, the anteroposterior width of neural spines of Deinocheirus is slightly narrower than that of Spinosaurus and Ouranosaurus. Based on these data and previous studies, we infer that the hyperelongated neural spines of Deinocheirus may serve dual functions: supporting a sail related to aquatic habits and a hump associated with an intricate interspinous ligament system, potentially for fat storage to aid in surviving dry seasons. Finally, we discuss avenues for future research, such as bone histology and finite element analysis, which could provide further insights into the morphology and function of the neural spines of Deinocheirus.
... The centrum seems to be unfused to other sacral vertebrae, which may also support the identification as a dorsosacral element or may indicate that it corresponds to an immature individual (Rauhut 2005;Brusatte et al. 2008). The sacral vertebrae are fused in Neovenator and Concavenator, but are unfused in Acrocanthosaurus and Sinraptor, while fusion is variable in Allosaurus (Madsen 1976a;Currie and Zhao 1993;Harris 1998;Brusatte et al. 2008;Cuesta et al. 2019). The centrum has a well-developed pleurocentral depression with no pleurocoels, as in the sacral vertebrae of several allosauroid theropods, such as Allosaurus, Neovenator, Sinraptor, and Tyrannotitan (Gilmore 1920;Madsen 1976a;Currie and Zhao 1993;Novas et al. 2005;Brusatte et al. 2008). ...
Malafaia, E., Mocho, P., Escaso, F., Narvaéz, I., and Ortega, F. 2024. Taxonomic and stratigraphic update of the material
historically attributed to Megalosaurus from Portugal. Acta Palaeontologica Polonica 69 (2): 127–171. https://doi.org/10.4202/app.01113.2023
... Poekilopleuron and possibly Juravenator have a distal process (Allain & Chure, 2002;Chiappe & Göhlich, 2010), which is less developed than Aucasaurus. A chevron-shaped morphology with an acute angle is typical of the posteriormost gastralia in several theropods, such as in Acrocanthosaurus, Poekilopleuron, Tyrannosaurus, or Troodon (Harris, 1998;Chure, 2000;Allain & Chure, 2002;Claessens, 2004). However, these taxa lack the triangular distal process observed in Aucasaurus. ...
Aucasaurus garridoi is an abelisaurid theropod from the Anacleto Formation (lower Campanian, Upper Cretaceous) of Patagonia, Argentina. The holotype of Aucasaurus garridoi includes cranial material, axial elements, and almost complete fore- and hind limbs. Here we present a detailed description of the axial skeleton of this taxon, along with some paleobiological and phylogenetic inferences. The presacral elements are somewhat fragmentary, although these show features shared with other abelisaurids. The caudal series, to date the most complete among brachyrostran abelisaurids, shows several autapomorphic features including the
presence of pneumatic recesses on the dorsal surface of the anterior caudal neural arches, a tubercle lateral to the prezygapophysis of mid caudal vertebrae, a marked protuberance on the lateral rim of the transverse process of the caudal vertebrae, and the presence of a small ligamentous scar near the anterior edge of the dorsal surface in the anteriormost caudal transverse process. The detailed study of the axial skeleton of Aucasaurus garridoi has also allowed us to identify characters that could be useful for future studies attempting to resolve the internal phylogenetic relationships of Abelisauridae. Computed tomography scans of some caudal vertebrae show pneumatic traits in neural arches and centra, and thus the first reported case for an abelisaurid taxon. Moreover, some osteological correlates of soft tissues present in Aucasaurus and other abelisaurids, especially derived brachyrostrans, underscore a previously proposed increase in axial rigidity within Abelisauridae.
... Acrocanthosaurus (Harris, 1998;Currie & Carpenter, 2000;Rauhut, 2003;, spinosaurids such as ...
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.
... Five sacral vertebrae are co-ossified, not only through their centra but also between the neural spines. In other carcharodontosaurids like Acrocanthosaurus 16 and Giganotosaurus, some neural spines show partial co-ossification of their distal parts, but never to the degree seen in Meraxes. The sacral spine-table has a sigmoid profile with the anterior-most and posterior-most spines projecting above the iliac margin in lateral view. ...
Giant carnivorous dinosaurs such as Tyrannosaurus rex and abelisaurids are characterized by highly reduced forelimbs that stand in contrast to their huge dimensions, massive skulls, and obligate bipedalism.¹,² Another group that follows this pattern, yet is still poorly known, is the Carcharodontosauridae: dominant predators that inhabited most continents during the Early Cretaceous3, 4, 5 and reached their largest sizes in Aptian-Cenomanian times.6, 7, 8, 9, 10 Despite many discoveries over the last three decades, aspects of their anatomy, especially with regard to the skull, forearm, and feet, remain poorly known. Here we report a new carcharodontosaurid, Meraxes gigas, gen. et sp. nov., based on a specimen recovered from the Upper Cretaceous Huincul Formation of northern Patagonia, Argentina. Phylogenetic analysis places Meraxes among derived Carcharodontosauridae, in a clade with other massive South American species. Meraxes preserves novel anatomical information for derived carcharodontosaurids, including an almost complete forelimb that provides evidence for convergent allometric trends in forelimb reduction among three lineages of large-bodied, megapredatory non-avian theropods, including a remarkable degree of parallelism between the latest-diverging tyrannosaurids and carcharodontosaurids. This trend, coupled with a likely lower bound on forelimb reduction, hypothesized to be about 0.4 forelimb/femur length, combined to produce this short-armed pattern in theropods. The almost complete cranium of Meraxes permits new estimates of skull length in Giganotosaurus, which is among the longest for theropods. Meraxes also provides further evidence that carchardontosaurids reached peak diversity shortly before their extinction with high rates of trait evolution in facial ornamentation possibly linked to a social signaling role.
... There is no trace of a ventral keel, unlike in tyrannosaurids and most other tetanurans (Rauhut, 2003b). One articular surface extends further ventrally than the other: in the dorsal vertebrae of tyrannosauroids and other tetanurans, it may be either the anterior or the posterior articular surface that extends furthest ventrally (Harris, 1998;Brochu, 2003;Brusatte, Carr & Norell, 2012), rendering it impossible to decide with certainty which end the ventrally descending one represents. The preserved height of the more extensive articular surface is 32 mm at most, but when complete it was probably c. 50 mm tall. ...
Eotyrannus lengi Hutt et al., 2001 from the Lower Cretaceous Wessex Formation (part of the Wealden Supergroup) of the Isle of Wight, southern England, is described in detail, compared with other theropods, and evaluated in a new phylogenetic analysis. Eotyrannus is represented by a single individual that would have been c. 4.5 m long; it preserves the anterior part of the skull, a partial forelimb and pectoral girdle, various cervical, dorsal and caudal vertebrae, rib fragments, part of the ilium, and hindlimb elements excluding the femur. Lack of fusion with regard to both neurocentral and sacral sutures indicates subadult status. Eotyrannus possesses thickened, fused, pneumatic nasals with deep lateral recesses, elongate, tridactyl forelimbs and a tyrannosaurid-like scapulocoracoid. The short preantorbital ramus of the maxilla and nasals that are approximately seven times longer than they are wide show that Eotyrannus was not longirostrine. A posterodorsally inclined ridge on the ilium's lateral surface fails to reach the dorsal margin: a configuration seen elsewhere in Juratyrant. Eotyrannus is not arctometatarsalian. Autapomorphies include the presence of curving furrows on the dentary, a block-like humeral entepicondyle, and a distoproximally aligned channel close to the distolateral border of the tibia. Within Tyrannosauroidea, E. lengi is phylogenetically intermediate between Proceratosauridae and Yutyrannus and the clade that includes Xiongguanlong, Megaraptora, Dryptosaurus and Tyrannosauridae. We do not find support for a close affinity between Eotyrannus and Juratyrant. Our analysis supports the inclusion of Megaraptora within Tyrannosauroidea and thus increases Cretaceous tyrannosauroid diversity and disparity. A proposal that Eotyrannus might belong within Megaraptora, however, is based on character states not present in the taxon. Several theropods from the Wessex Formation are based on material that overlaps with the E. lengi holotype but none can be shown to be synonymous with it. Subjects Paleontology, Zoology
... The neural spine of the axis of Maip lacks a transversally wide spine table as the observed in tyrannosaurids 43,50 . Nevertheless, the neural spine of Maip is notably low, being slightly lower than those of Allosaurus or Tyrannosaurus but much lower when compared with carcharodontosaurids (such as Acrocanthosaurus or Concavenator; 51,52 ). In Maip the postzygapophyses are round being slightly transversally wider than anteroposteriorly long, which seems the condition for Tyrannosaurus 43 . ...
Megaraptorans are a theropod clade distributed in former Gondwana landmasses and Asia. Most members of the clade are known from early Cretaceous to Turonian times whereas Maastrichtian megaraptorans are known just from isolated and poorly informative remains. The aim of present contribution is to describe a partial skeleton of a megaraptorid coming from Maastrichtian beds at Santa Cruz province, Argentina. This new taxon constitutes the most informative megaraptoran from post-Turonian beds. Phylogenetic analysis nested the new taxon together with South American megaraptorans in a monophyletic clade, whereas Australian and Asian members constitute successive stem groups. South American forms differ from more basal megaraptorans in several anatomical features and in being much larger and more robustly built. It is possible that the Cenomanian-Turonian extinction of carcharodontosaurids was allowed to megaraptorans to occupy the niche of top predators in South America.
... The Laurasian records consist of fragmentary materials from Upper Jurassic strata of China (Brusatte et al. 2009), Portugal (Malafaia et al. 2019, Lower Cretaceous of England and Spain (Ortega et al. 2010, Cuesta et al. 2018. The analysis of a tooth from Romania also indicates the presence of carcharodontosaurids in the Valanginian of Laurasia, but such assignment is still dubious due From the Jurassic to the Lower Cretaceous, the sole occurrence is the allosauroid Acrocanthosaurus which could be a putative carcharodontosaurian from North America (Harris 1998, Currie & Carpenter 2000. Among the Gondwanan carcharodontosaurian record, is remarkable the diversification of the clade especially from South America (Patagonia, Argentina;Novas et al. 2013). ...
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.
... obs.), Lourinhanosaurus (Mateus 1998;ML370, P.M.S. pers. obs.), Concavenator (Cuesta et al. 2019), and Acrocanthosaurus (Harris 1998), as well as in several coelurosaurs (e.g., Zanno 2010;Choiniere et al. 2010;Novas et al. 2012). However, the morphology of ventral groove is different in each theropod as stated above. ...
We report theropod caudal vertebrae found at Phu Wiang Mountain, Thailand. They resemble the Portuguese Baryonyx and pertain to the Spinosauridae based on the presence of striations on the surface of the transverse process of the caudals, well developed double keels and a deep ventral groove on the centra, two laminae, delimiting three fossae below the transverse process, and posterior caudals having curved, rod-like neural spines with small process at the base. This supports the presence of spinosaurids in the Sao Khua Formation of Thailand. Furthermore, the putative basal ceratosaur Camarillasaurus Sánchez- Hernández and Benton, 2014 from Spain is found here to be a spinosaurid based on the resemblance of the type materials to the Thai spinosaurid described in the present work, as well as the phylogenetic analysis and the similarity to other spinosaurids. In Europe, spinosaurids have been reported from England, Portugal, and Spain. The reassessment of Camarillasaurus adds to the number of this group in this region. The presence of more than one spinosaurid taxon in the same region is common and can be found in the Kem Kem Beds of Morocco, the Araripe Basin of Brazil, the Iberian Peninsula, and the Khorat Plateau of Southeast Asia.
... Tyrannosauroids, compsognathids, and dromaeosaurids were strictly carnivorous, whereas ornithomimosaurs, alvarezsauroids, therizinosaurs, and oviraptorosaurs were omnivorous and/or herbivorous. Carnivorous and herbivorous theropods are found among troodontids and birds Typical carnivorous theropods, such as Acrocanthosaurus from the Early Cretaceous of North America, bear relatively large-sized and posteriorly recurved teeth with serrated * edges made of tiny denticles (Harris 1998). These bladeshaped teeth, known as ziphodont teeth (Hendrickx et al. 2015b), were perfectly adapted to inflict fatal injuries and cut through flesh (D'Amore 2009). ...
If we imagine walking through Mesozoic lands, we would be able to observe vertebrates with peculiar combinations of morphological traits, some of which would seem to be intermediary to animals seen today. We would witness a terrestrial vertebrate fauna dominated by dinosaurs of various sizes and diversity, accompanied by many other animal groups that often are overlooked. Current research suggests that many of the main vertebrate clades existing today originated or diversified sometime in the Triassic or Early to Middle Jurassic. Herein, we profile some of the major transformations in both terrestrial and aquatic vertebrate evolution during the Mesozoic. We highlight: the appearance of features that allowed sauropod dinosaurs to become the largest animals to ever walk on Earth’s continents, the appearance of herbivory among the usually carnivorous theropod dinosaurs, and we follow the specific changes that led to the evolution of avian flight. Our Mesozoic tour across the globe will allow us to see how different evolutionary forces led to convergent shifts to quadrupedality in ornithischian dinosaurs and to an aquatic lifestyle in turtles, crocodiles, and plesiosaurs. Last, but not least, we examine changes in the Mesozoic fauna linked to the rise of mammals, and the diversification patterns in several clades of fishes after the End-Permian Mass Extinction.
... Despite the similarity of Late Jurassic faunas from the Morrison Formation and the Lusitanian Basin, carcharodontosaurian allosauroids are absent in the former area. The development of a terrestrial dispersal route between Europe and North America after the late Tithonian could explain the absence of this clade in the Morrison Formation and, additionally, their presence during the Early and Late Cretaceous of North America (e.g., Harris, 1998;Zanno and Makovicky, 2013). A land reconnection between Europe and North America due to a drop in sea level during the mid-Valanginian (ca. ...
Carcharodontosaurian allosauroids were temporally restricted to the Cretaceous, being known from all land masses with the exception of Antarctica. In addition to Veterupristisaurus from Tanzania, exceptions to this distribution have been reported recently, consisting on fragmentary materials from Upper Jurassic strata of China, Germany, and Portugal. Here, we propose a new Late Jurassic carcharodontosaurian taxon, Lusovenator santosi, gen. et sp. nov. based on the reevaluation of previously described specimens from the Lusitanian Basin, Portugal. The performed phylogenetic analysis recovered Lusovenator santosi as an early branching carcharodontosaurian allosauroid diagnosed by an exclusive combination of characters, including three autapomorphic features: (1) large recesses in neural arch of anterior dorsal vertebrae; (2) well-developed and continuous longitudinal laminae extending from the tip of the prezygapophyses to the distal end of the postzygapophyses in mid-caudal vertebrae; and (3) supraacetabular crest of ilium forming a prominent ventrolaterally projecting shelf. Lusovenator santosi is the oldest carcharodontosaurian allosauroid yet discovered from Laurasia and supports unequivocally the hypothesis of a pre-Cretaceous scenario for the radiation of the clade. The identification of this taxon highlights the high diversity of medium- to large-bodied theropods in the later part of the Late Jurassic of the Iberian Peninsula. Carcharodontosauria is not yet known in correlative levels of the North American Morrison Formation, and the existence of contacts after the late Tithonian between these landmasses could explain the distribution of this clade and other dinosaur groups present in the Iberian Jurassic and in the North American Lower Cretaceous.
... This condition is different from that in Carcharodontosaurus, which has pleurocoels in its anterior caudal vertebrae (Stromer, 1931). Furthermore, the strongly waisted centrum morphology, a double keel cut by a longitudinal groove and offset articular facets (although it is a plesiomorphic feature found in Allosaurus Gilmore, 1920;Madsen, 1976) are also found in specimens such as the carcharodontosaurid material from Sudan (Rauhut, 1999) and in Tyrannotitan, Mapusaurus and Acrocanthosaurus (Harris, 1998;Currie and Carpenter, 2000;Coria and Currie, 2006;Canale et al., 2015). Referred material: UFRJ-DG 558-R e 634-R. ...
The theropod record from the Cretaceous of northeastern Brazil are rare and consist mostly of isolated and incomplete remains, with only four species described. Here we describe, identify and evaluate the diversity of theropod materials from the Albian-Cenomanian Açu Formation, Potiguar Basin. The material consists of seven isolated theropod vertebrae and a tooth. We identify the material as belonging to four theropod groups: Spinosauroidea, Carcharodontosauria, Megaraptora, and Maniraptora. One of the significant results is the occurrence of Megaraptora in the Potiguar Basin; based on the general morphology, some of the bones we describe are very similar to those of Aerosteon and Megaraptor. Another unexpected result is the identification and presence of a maniraptoran caudal vertebrae; these dinosaurs are very rare in Brazil, with few fossils previously described. Furthermore, we identify other groups that have already been found in isochronous basins of the Northeast region of Brazil and Africa, including Carcharodontosauria and Spinosauroidea. The presence of these theropod groups in the Açu Formation reveals a dinosaur richness in in the Potiguar Basin similar to isochronous basins in Northern Africa and increases knowledge about the diversity of South American dinosaurs.
... No es posible verificar la presencia de hipósfeno-hipantro en ninguno de los dos ejemplares. La longitud relativa y la ausencia de pleurocelos centrales está compartida por Allosaurus y difiere de la que presentan otros alosauroideos, como Acrocanthosaurus (Britt 1993, Harris 1998, Stovall & Langston 1950. ...
Malafaia E, Dantas P, Ortega F, Escaso F. 2007. Nuevos restos de Allosaurus fragilis (Theropoda: Carnosauria) del yacimiento de Andrés (Jurásico Superior; Centro-Oeste de Portugal). Libro de resúmenes V Encuentro de Jóvenes Investigadores en Paleontología: 255-271.
... The ventral surface of the axial intercentrum is horizontal, as in some non-tetanuran theropods, Piatnitzkysaurus 9 and the possible megalosaurid Leshansaurus 16 . In contrast, the ventral surface of the intercentrum is inclined anterodorsally relative to the ventral surface of the axis, such that the two form an oblique angle as in Monolophosaurus 19 and some allosauroids such as Acrocanthosaurus 21 , Giganotosaurus (IVPP V 7265) and Sinraptor 13 . The axial centrum is platycoelous, with a flat anterior surface. ...
Tetanurae is a special group of theropod dinosaurs that originated by the late Early Jurassic. It includes several early-diverging groups of generally large-bodied predators (megalosauroids, allosauroids, tyrannosauroid coelurosaurs) as well as morphologically disparate small-bodied coelurosaurs, including birds. Aspects of the evolutionary history of tetanurans remain contested, including the topology of their deep phylogenetic divergences (among Megalosauroidea, Allosauroidea and Coelurosauria). We report a new theropod, Yunyangosaurus puanensis gen. et sp. nov., based on a fragmentary specimen recovered from the Middle Jurassic Xintiangou Formation of Chongqing, southwestern China. It shares several features uniquely with some megalosauroids (the clade of megalosaurids + spinosaurids + piatnitzkysaurids), such as prominent rims around the anterior articular surfaces of cervical centra and bifurcated anterior dorsal neural spines (present in piatnitzkysaurids). Nevertheless, it also shows several features that are rare or absent among megalosauroids and more crownward tetanurans, including prominent spinopostyzgopophyseal laminae (also present in non-tetanurans and metriacanthosaurid allosauroids), flat anterior articular surfaces of the cervical centra (also present in piatnitzkysaurids and some earlier-diverging tetanurans), and the presence of a posterior pneumatic foramen or fossa (absent in most tetanurans, but sporadically present in some cervical vertebrae of piatnitzkysaurids). Yunyangosaurus therefore presents a combination of derived and apparently primitive character states that are not seen in other theropods. This suggests that patterns of morphological evolution associated with deep tetanuran divergences were more complex than currently recognized, with implications for understanding the character evolution in theropods.
... Other archosaur taxa recovered with the Proctor Lake ornithopod include a crocodyliform, Wannchampsus kirpachi [8], and a single tooth of a dromaeosaur. The upper portion of the Twin Mountains contains a variety of fauna, including the crocodyliform Paluxysuchus newmani [9], sauropod remains at the Jones Ranch site [10; 11], the theropod Acrocanthosaurus atokensis [12], and the ornithopod Tenontosaurus dossi [13]. Fig 1. Map of study area. ...
Material from a minimum of twenty-nine individuals of a new ornithopod, represented by nearly every skeletal element, was recovered from the Proctor Lake locality in the Twin Mountains Formation (Aptian) of north-central Texas. This material includes various ontogenetic stages, providing insight into the growth patterns of this species. The new ornithopod, Convolosaurus marri gen. et sp. nov., is recovered outside of Iguanodontia, but forms a clade with Iguanodontia exclusive of Hypsilophodon foxii. The presence and morphology of four premaxillary teeth along with a combination of both basal and derived characters distinguish this taxon from all other ornithopods. Basal characters present in C. marri including the presence of premaxillary teeth, the shape of the dentary teeth, and position of the pterygoid wing on the quadrate, whereas the presence of opisthocoelous cervical vertebrae, large proximal caudal neural spines, and curved maxillary tooth roots suggest C. marri is more derived than 80% of the basal neornithischians included in this analysis.
... We checked our mass estimation method against that of Bates et al. (2009a) by digitizing their illustrations of Acrocanthosaurus atokensis, including the body and the animal's dorsal fin separately. The dorsal fin was restored with half a centimeter of tissue on either side the neural spines, with a bony width of approximately four cm that Harris (1998) reported for the twelfth dorsal vertebra. We assumed a rectangular cross-section for the fin. ...
Synopsis
Tyrannosaurid dinosaurs had large preserved leg muscle attachments and low rotational inertia relative to their body mass, indicating that they could turn more quickly than other large theropods.
Methods
To compare turning capability in theropods, we regressed agility estimates against body mass, incorporating superellipse-based modeled mass, centers of mass, and rotational inertia (mass moment of inertia). Muscle force relative to body mass is a direct correlate of agility in humans, and torque gives potential angular acceleration. Agility scores therefore include rotational inertia values divided by proxies for (1) muscle force (ilium area and estimates of m. caudofemoralis longus cross-section), and (2) musculoskeletal torque. Phylogenetic ANCOVA (phylANCOVA) allow assessment of differences in agility between tyrannosaurids and non-tyrannosaurid theropods (accounting for both ontogeny and phylogeny). We applied conditional error probabilities a ( p ) to stringently test the null hypothesis of equal agility.
Results
Tyrannosaurids consistently have agility index magnitudes twice those of allosauroids and some other theropods of equivalent mass, turning the body with both legs planted or pivoting over a stance leg. PhylANCOVA demonstrates definitively greater agilities in tyrannosaurids, and phylogeny explains nearly all covariance. Mass property results are consistent with those of other studies based on skeletal mounts, and between different figure-based methods (our main mathematical slicing procedures, lofted 3D computer models, and simplified graphical double integration).
Implications
The capacity for relatively rapid turns in tyrannosaurids is ecologically intriguing in light of their monopolization of large (>400 kg), toothed dinosaurian predator niches in their habitats.
... We checked our mass estimation method against that of Bates et al. (2009a) by digitizing their illustrations of Acrocanthosaurus atokensis, including the body and the animal's dorsal fin separately. The dorsal fin was restored with half a centimeter of tissue on either side the neural spines, with a bony width of approximately four cm that Harris (1998) reported for the twelfth dorsal vertebra. We assumed a rectangular cross-section for the fin. ...
Synopsis: Tyrannosaurid dinosaurs had larger than predicted preserved leg muscle attachments and low rotational inertia relative to their body mass, indicating that they could turn more quickly than other large theropods. Methods: To compare turning capability in theropods, we regressed agility estimates against body mass, incorporating superellipse-based modeled mass, centers of mass, and rotational inertia (mass moment of inertia). Muscle force relative to body mass is a direct correlate of agility in humans, and torque gives potential angular acceleration. Agility scores therefore include rotational inertia values divided by proxies for (1) muscle force (ilium area and estimates of m. caudofemoralis longus cross-section), and (2) musculoskeletal torque. Phylogenetic ANCOVA (phylANCOVA) allow assessment of differences in agility between tyrannosaurids and non-tyrannosaurid theropods (accounting for both ontogeny and phylogeny). We applied conditional error probabilities a(p) to stringently test the null hypothesis of equal agility. Results: Tyrannosaurids consistently have agility index magnitudes twice those of allosauroids and some other theropods of equivalent mass, turning the body with both legs planted or pivoting over a stance leg. PhylANCOVA demonstrates definitively greater agilities in tyrannosaurids, and phylogeny explains nearly all covariance. Mass property results are consistent with those of other studies based on skeletal mounts, and between different figure-based methods (our main mathematical slicing procedures, lofted 3D computer models, and simplified graphical double integration). Implications: The capacity for relatively rapid turns in tyrannosaurids is ecologically intriguing in light of their monopolization of large (>400 kg), toothed dinosaurian predator niches in their habitats.
... Recently, a single carcharodontosaurid theropod tooth from the Valanginian of Romania (Csiki-Sava et al. 2016) has been proposed as the earliest evidence of Carcharodontosauridae in Europe. Carcharodontosaurid carcharodontosaurians are also found in Gondwanan deposits from the Early Cretaceous (Novas et al. 2005;Fanti et al. 2014), and in North America they are represented by the Albian genus Acrocanthosaurus (Sereno et al. 1996;Harris 1998;Brusatte and Sereno 2008;Csiki-Sava et al. 2016), becoming abundant and diverse in the course of the "Middle" and Late Cretaceous (Csiki-Sava et al. 2016). Non-carcharodontosaurid carcharodontosaurians are represented by Neovenator (Hutt et al. 1996) from the Barremian Wealden of England, which shares the features seen in this morphotype. ...
Introduction: Barranco del Hocino-1 is a new fossil site located near Estercuel, Teruel province, Spain. The fossil site is located geologically within the Oliete sub-basin, in the Blesa Formation (Barremian in age). Barranco del Hocino-1 shows a diverse assemblage of tetrapod vertebrates similar to other sites in the Blesa Formation. Materials and methods: Six isolated teeth belonging to Theropoda have been found. A study of their qualitative and quantitative characters, along with statistical (DFA) and cladistic analyses, enable us to identify four different dental morphotypes. Results: These morphotypes belong to separate tetanuran theropod taxa. One is related to Spinosauridae. The other morphotypes show affinities with non-spinosaurid tetanurans, probably related to Carcharodontosauria. Conclusions: The results are congruent with the known theropod record of the Iberian Peninsula and western Europe. This work is a new contribution to what is known of the palaeobiodiversity and distribution of large-bodied theropods from the Barremian of the Iberian Peninsula. © 2018, Springer International Publishing AG, part of Springer Nature.
... The low genus-level similarity between the faunas is likely augmented because of the lack of specimens from the Arundel assignable to specific genera, as half the genera known from the Arundel (Deinonychus, Acrocanthosaurus, Tenontosaurus) are known from the Cloverly and Ruby Ranch faunas (Table 1 of Appendix 1). Acrocanthosaurus and Deinonychus specimens have also been collected from the Twin Mountain and Antlers formations of Texas and Oklahoma (Stovall and Langston, 1950;Cifelli, 1997;Harris, 1998;Currie and Carpenter, 2000;, and in addition to the common occurrence of Tenontosaurus remains (e.g., Ostrom, 1970;Forster, 1984;Forster, 1990;Winkler et al., 1997;Weishampel et al., 2004), the ankylopollexian iguanodontians Hippodraco and Theiophytalia are present during the Aptian in the American west (Brill and Carpenter, 2006;. The lack of reported ornithomimosaur material from the Ruby Ranch member of the Cedar Mountain Formation is not regarded as significant, as the possible ornithomimosaur Nedcolbertia justinhofmanni is known from the slightly older Yellow Cat Member of the Cedar Mountain Formation (Brownstein, 2017a;Kirkland and Hunt-Foster, 2017). ...
The Cenomanian to Maastrichtian of the Late Cretaceous saw the flooding of the interior of North America by the Western Interior Seaway, which created the eastern landmass of Appalachia and the western landmass of Laramidia. Though Appalachian dinosaur faunas are poorly known, they are nevertheless important for understanding Cretaceous dinosaur paleobiogeography and ecology. In order to better track the vicariance of eastern and western North American dinosaur faunas over the duration of the Cretaceous, the former were compared with the latter from the Aptian to Maastrichtian Stages of the Late Cretaceous using several similarity indices. The data gathered from biogeographic similarity indices suggest that an almost completely homogenous North American dinosaur fauna found in the Early Cretaceous experienced significant vicariance, splitting into a Laramidian fauna differentiated by the presence of ceratopsids, pachycephalosaurids, saurolophids, lambeosaurines, ankylosaurids, therizinosaurids, and troodontids and an Appalachian fauna characterized by the lack of the aforementioned groups and the presence of non-hadrosaurid hadrosauroids, massive hadrosauroids, basal hadrosaurids, leptoceratopsians, “intermediate”-grade tyrannosauroids, and nodosaurids between the Cenomanian and Campanian, with these two faunas later experiencing limited dispersal after the disappearance of the Western Interior Seaway from the American Interior during the Maastrichtian. Dinosaur provincialism and ecology on Appalachia are also investigated and discussed. Though the fossil record of dinosaurs for parts of the Cretaceous is poor throughout North America and in the eastern portion of the continent especially, the analyses herein nevertheless allow for a greater glimpse at dinosaur biogeography and ecology in Appalachia and in North America generally during the time.
... The size of the pleurocoel reduces gradually and the opening becomes more dorsoventrally lower towards the caudal series. The presence of sacral pleurocoels has been reported in several theropod clades, such as carcharodontosaurids, oviraptorosaurs, ornithomimosaurs, tyrannosaurids, and megaraptorans (Harris, 1998;Brochu, 2003;Rauhut, 2003 (Frey and Martill, 1995). These pneumatic foramina are subdivided by thin laminae in the two most posterior sacral vertebrae. ...
A specimen composed of a partial sacrum articulated to two anterior caudal vertebrae and an ilium (SMNS 58023) from the Lower Cretaceous (Albian) Santana Formation of Brazil was originally described as an oviraptorosaur, but it is here re-interpreted as the oldest megaraptoran of South America. The phylogenetic relationships of SMNS 58023 were tested quantitatively for the first time including it in the two most comprehensive phylogenetic data sets focused on non-maniraptoran theropods –including megaraptorans. The Brazilian specimen was consistently found as a megaraptoran in both analyses because of the presence of sacral centra longer than tall, absence of a median transverse constriction of sacral centra, and the morphology and position of sacral pleurocoels. SMNS 58023 sheds light on a region of the body that is poorly known in megaraptorans and pulls back the temporal range of the clade in South America. This re-interpretation reinforces the absence of oviraptorosaurs in Gondwana.
... The most distinctive feature of this morphotype is the large size of some crowns, which is comparable with Torvosaurus (Britt 1991;Hendrickx et al. 2015), Tyrannosaurus (Smith 2005;Brochu 2003) and some carcharodontosaurids such as Acrocanthosaurus (Harris 1998;Currie and Carpenter 2000). These teeth are comparable to other specimens previously described in the Upper Jurassic of the Lusitanian Basin and assigned to Torvosaurus Mateus 2014a, 2014b;Hendrickx et al. 2015). ...
Purpose
Isolated theropod teeth are abundant in the Upper Jurassic of the Lusitanian Basin and are an important source to reconstruct the diversity of this group as well as its geographic and stratigraphic distribution. However, reliably identification of isolated teeth is complex, especially for those morphotypes related to poorly represented groups. Herein a set of isolated theropod teeth collected in different sites from the Upper Jurassic of the Lusitanian Basin ranging from the late Kimmeridgian to late Tithonian in age are described and discussed.
Methods
These teeth were grouped in seventeen distinct morphotypes based first on morphology and comparative anatomy. Multivariate statistical analyses were performed in order to assign each morphotype to a certain taxon.
Results
The current analysis shows the presence of several groups of theropods such as Ceratosaurus, Torvosaurus, and Allosaurus beside morphotypes identified as belonging to indeterminate Megalosauroidea and Allosauroidea and morphotypes tentatively assigned to Tyrannosauroidea, Dromaeosauridae, and Richardoestesia. This faunal composition, namely the presence of a non-megalosaurid megalosauroid possibly related to the piatnitzkysaurid Marshosaurus, indicates a higher diversity of theropods in the Late Jurassic of the Lusitanian Basin than previously known, based on more complete specimens. Results obtained from this analysis partially agree with previous studies of other collections with isolated theropod teeth from the Upper Jurassic of Portugal such as those of the Guimarota coal mine. However, the presence of velociraptorine dromaeosaurids, compsognathids, and troodontids reported from this site could not be confirmed in the sample herein analyzed. This analysis also indicates a great similarity of the theropod faunas from the Late Jurassic of the Lusitanian Basin and other European chronocorrelative localities such as those from Spain and Germany.
... It is fan-shaped, showing concave anterior and posterior margins; it is notably compressed transversely. The top of the neural spine does not form a spine table, but shows rugose margins that indicate the presence of strong ligament attachments (Harris, 1998). The centrum matches the camerate kind of pneumaticity described above for the cervical vertebrae. ...
Buitreraptor gonzalezorum is a theropod dinosaur belonging to the clade Unenlagiidae. It is known by several specimens coming from the Upper Cretaceous of Northwestern Patagonia, Argentina. In spite of its completeness, only a preliminary description of its postcranial anatomy is available. The aim of the present contribution is to make a detailed anatomical description of the postcranial skeleton of a newly discovered Buitreraptor gonzalezorum specimen. Comparisons with a large number of paravians are also carried out. This resulted in the finding of potentially phylogenetically informative characters with deep implications on early paravian evolution. The new individual sheds light on anatomical elements and allows recognition of new autapomorphies, as well as possible synapomorphies of the clade Unenlagiidae.
A series of axial elements from the Aptian Ferrug-inous Sands Formation of the Lower Greensand Group, discovered on the foreshore near Knock Cliff on the Isle of Wight, UK are (bar some isolated teeth and fragmentary post-cranial material from the Cenomanian Cambridge Greensand) the youngest non-avian theropod remains reported from the British Mesozoic. These specimens have the potential to shed light on a poorly known section of the European dinosaur record. Consistency in size, appearance and adhering matrix indicates that the vertebrae belong to the same individual. This was a mid-sized tetanuran, the presence of several diagnostic characters indicating that it should be recognized as a new taxon, herein named Vectaerovenator inopinatus. The cervical and dorsal vertebrae are camerate and highly pneumatic. Tetanuran features include opisthocoelous cervicals and pneumatic foramina located within fossae; however, assigning this specimen to a specific clade is problematic. Within Tetanurae, Vectaerovenator possesses axial structures and homoplastic features seen in megalosauroids, carcharodontosaurians and certain coelurosaurs. Not only is Vectaerovenator one of the UK's youngest non-bird dinosaurs, and one of few valid British Greensand taxa, it is also the first diagnosable theropod taxon to be named from Aptian deposits of Europe.
Remains of enigmatic spinosaurs from mid-Cretaceous North African strata have, for over a century, been the subject of taxonomic deliberations. The gigantic Spinosaurus aegyptiacus Stromer, 1915 has gained iconic status in the vertebrate palaeontological community and amongst the general public. Perhaps the largest predatory dinosaur to have lived, this animal exhibits a bizarre range of adaptations consistent with a piscivorous diet and semiaquatic mode of life. Despite its popularity, the systematics of this taxon remains a matter of considerable debate. African spinosaur taxonomy is complex, with up to three separate species proposed for the Cretaceous Kem Kem Group of Morocco: Spinosaurus aegyptiacus, Spinosaurus maroccanus Russell, 1996 and Sigilmassasaurus brevicollis Russell, 1996.
Here, the taxonomic status of spinosaurs in the Kem Kem Group is examined, and the morphology of the cervical and dorsal vertebrae re-evaluated in the light of this taxonomic reappraisal.
The validity of Spinosaurus maroccanus and Sigilmassasaurus brevicollis are not supported, as all autapomorphies of these taxa are proposed here to be the result of intraspecific variation, or morphological changes through the axial column of a single taxon. Both taxa are junior synonyms of Spinosaurus aegyptiacus.
This reanalysis has implications for the taxonomy of spinosaurs from other deposits. Based on the currently available material, the Brazilian spinosaurid Oxalaia quilombensis is determined to fall within the Spinosaurus aegyptiacus hypodigm. The prevalence of spinosaurid heterodonty and limited diagnostic potential of spinosaur teeth necessitates that two spinosaurid tooth taxa: Ostafrikasaurus crassiserratus and Siamosaurus suteethorni, be regarded nomina dubia.
The geological and paleoenvironmental setting and the vertebrate taxonomy of the fossiliferous, Cenomanian-age deltaic sediments in eastern Morocco, generally referred to as the “Kem Kem beds”, are reviewed. These strata are recognized here as the Kem Kem Group, which is composed of the lower Gara Sbaa and upper Douira formations. Both formations have yielded a similar fossil vertebrate assemblage of predominantly isolated elements pertaining to cartilaginous and bony fishes, turtles, crocodyliforms, pterosaurs, and dinosaurs, as well as invertebrate, plant, and trace fossils. These fossils, now in collections around the world, are reviewed and tabulated. The Kem Kem vertebrate fauna is biased toward largebodied carnivores including at least four large-bodied non-avian theropods (an abelisaurid, Spinosaurus, Carcharodontosaurus, and Deltadromeus), several large-bodied pterosaurs, and several large crocodyliforms.
No comparable modern terrestrial ecosystem exists with similar bias toward large-bodied carnivores. The Kem Kem vertebrate assemblage, currently the best documented association just prior to the onset of the Cenomanian-Turonian marine transgression, captures the taxonomic diversity of a widespread northern African fauna better than any other contemporary assemblage from elsewhere in Africa.
Keywords
Africa, Cretaceous, dinosaur, Gara Sbaa Formation, Douira Formation, paleoenvironment, vertebrate
Evolutionary teratology recognises certain anatomical modifications as developmental anomalies. Within non avian-theropod dinosaurs, the strong forelimb shortening of Tyrannosauridae, Carnotaurinae and Limusaurus – associated with a reduction or loss of autonomy – have been previously diagnosed as evolutionary anterior micromelias. The feature is here examined with Acrocanthosaurus atokensis (Carcharodontosauridae) and Gualicho shinyae (Neovenatoridae). The micromelic diagnosis is confirmed for Acrocanthosaurus, without supplementary malformations. Gualicho is considered as a borderline case, outside of the micromelic spectrum, but shows a total phalangeal loss on digit III. The reduction in the biomechanical range of Acrocanthosaurus’ forelimbs was compensated by the skull and jaws as main predatory organs. The same is assumed for Gualicho, but its robust first digit and raptorial claw are to be underlined. Other gigantic-sized and derived representatives of Carcharodontosauridae probably shared the anterior micromelia condition, potentially due to developmental modifications involving differential forelimbs/hindlimbs embryological growth rates, secondarily associated with post-natal growth rates leading to large and gigantic sizes; a converging state with Tyrannosauridae. Nevertheless, whereas developmental growth rates are also considered in the shortened condition of Gualicho, there is no association with post-natal gigantism. Finally, the digit III reduction likely followed the same evolutionary pathways as Tyrannosauridae, potentially involving BMPs, Fgfs and Shh signalling.
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 theropod teeth are some of the most common fossils in the dinosaur fossil record and are continually reported in the literature. Recently developed quantitative methods have improved our ability to test the affinities of isolated teeth in a repeatable framework. But in most studies, teeth are diagnosed on qualitative characters. This can be problematic because the distribution of theropod dental characters is still poorly documented, and often restricted to one lineage. To help in the identification of isolated theropod teeth, and to more rigorously evaluate their taxonomic and phylogenetic potential, we evaluated dental features in two ways. We first analyzed the distribution of 34 qualitative dental characters in a broad sample of taxa. Functional properties for each dental feature were included to assess how functional similarity generates homoplasy. We then compiled a quantitative data matrix of 145 dental characters for 97 saurischian taxa. The latter was used to assess the degree of homoplasy of qualitative dental characters, address longstanding questions on the taxonomic and biostratigraphic value of theropod teeth, and explore the major evolutionary trends in the theropod dentition.
In smaller phylogenetic datasets for Theropoda, dental characters exhibit higher levels of homoplasy than non-dental characters, yet they still provide useful grouping information and optimize as local synapomorphies of smaller clades. In broader phylogenetic datasets, the degree of homoplasy displayed by dental and non-dental characters is not significantly different. Dental features on crown ornamentations, enamel texture, and tooth microstructure have significantly less homoplasy than other dental features and can be used to identify many theropod taxa to ‘family’ or ’sub-family’ level, and some taxa to genus or species. These features should, therefore, be a priority for investigations seeking to classify isolated teeth.
Our observations improve the taxonomic utility of theropod teeth and in some cases can help make isolated teeth useful as biostratigraphic markers. This proposed list of dental features in theropods should, therefore, facilitate future studies on the systematic paleontology of isolated teeth.
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.
Synopsis: Tyrannosaurid dinosaurs had larger than predicted preserved leg muscle attachments and low rotational inertia relative to their body mass, indicating that they could turn more quickly than other large theropods. Methods: To compare turning capability in theropods, we regressed agility estimates against body mass, incorporating superellipse-based modeled mass, centers of mass, and rotational inertia (mass moment of inertia). Muscle force relative to body mass is a direct correlate of agility in humans, and torque gives potential angular acceleration. Agility scores therefore include rotational inertia values divided by proxies for (1) muscle force (ilium area and estimates of m. caudofemoralis longus cross-section), and (2) musculoskeletal torque. Phylogenetic ANCOVA (phylANCOVA) allow assessment of differences in agility between tyrannosaurids and non-tyrannosaurid theropods (accounting for both ontogeny and phylogeny). We applied conditional error probabilities a(p) to stringently test the null hypothesis of equal agility. Results: Tyrannosaurids consistently have agility index magnitudes twice those of allosauroids and some other theropods of equivalent mass, turning the body with both legs planted or pivoting over a stance leg. PhylANCOVA demonstrates definitively greater agilities in tyrannosaurids, and phylogeny explains nearly all covariance. Mass property results are consistent with those of other studies based on skeletal mounts, and between different figure-based methods (our main mathematical slicing procedures, lofted 3D computer models, and simplified graphical double integration). Implications: The capacity for relatively rapid turns in tyrannosaurids is ecologically intriguing in light of their monopolization of large (>400 kg), toothed dinosaurian predator niches in their habitats.
ResearchGate has not been able to resolve any references for this publication.