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A new clade of archaic large-bodied predatory dinosaurs (Theropoda: Allosauroidea) that survived to the latest Mesozoic

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Roger B J Benson
Roger B J Benson
Roger B J Benson
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Matthew T Carrano at Smithsonian Institution
Matthew T Carrano
Stephen L Brusatte at University of Edinburgh
Stephen L Brusatte
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Abstract and Figures

Non-avian theropod dinosaurs attained large body sizes, monopolising terrestrial apex predator niches in the Jurassic-Cretaceous. From the Middle Jurassic onwards, Allosauroidea and Megalosauroidea comprised almost all large-bodied predators for 85 million years. Despite their enormous success, however, they are usually considered absent from terminal Cretaceous ecosystems, replaced by tyrannosaurids and abelisaurids. We demonstrate that the problematic allosauroids Aerosteon, Australovenator, Fukuiraptor and Neovenator form a previously unrecognised but ecologically diverse and globally distributed clade (Neovenatoridae, new clade) with the hitherto enigmatic theropods Chilantaisaurus, Megaraptor and the Maastrichtian Orkoraptor. This refutes the notion that allosauroid extinction pre-dated the end of the Mesozoic. Neovenatoridae includes a derived group (Megaraptora, new clade) that developed long, raptorial forelimbs, cursorial hind limbs, appendicular pneumaticity and small size, features acquired convergently in bird-line theropods. Neovenatorids thus occupied a 14-fold adult size range from 175 kg (Fukuiraptor) to approximately 2,500 kg (Chilantaisaurus). Recognition of this major allosauroid radiation has implications for Gondwanan paleobiogeography: The distribution of early Cretaceous allosauroids does not strongly support the vicariant hypothesis of southern dinosaur evolution or any particular continental breakup sequence or dispersal scenario. Instead, clades were nearly cosmopolitan in their early history, and later distributions are explained by sampling failure or local extinction.
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Supplementary resource (1)

Supplementary Material
Data
January 2010
Roger B. J. Benson · Matthew T Carrano · Stephen L Brusatte
... Alleged ceratosaurs have previously been reported from Australia: Rauhut (2005) referred the Middle Jurassic Ozraptor subotaii Long and Molnar 1998 to the Abelisauroidea, and Agnolin et al. (2010) referred an Early Cretaceous 'Allosaurus' astragalus (Molnar et al. 1981) to Abelisauroidea. Subsequent study has shown that the former material is not diagnostic (Carrano and Sampson 2008;Agnolin et al. 2010;Barrett et al. 2010) and that the 'Allosaurus' astragalus is assignable to a neovenatorid allosauroid (Hocknull et al. 2009;Benson et al. 2010a; see discussion below). Thus, the fossil described here represents the first diagnostic evidence for the Ceratosauria in Australia and sheds light on the diversity and biogeography of dinosaurs in eastern Gondwana. ...
... NMV P221202 differs from basal Tetanurae (Rauhut 2003;Carrano and Sampson 2008) in having: a coossified astragalus and calcaneum; an ascending process of the astragalus with an approximately parallel-sided base; and a distinct fossa at the base of the ascending process that is not associated with a transverse groove. NMV P221202 differs from megaraptoran allosauroids (Benson et al. 2010a) and Coelurosauria (Welles and Long 1974) in having: an ascending process that is less than twice the dorsoventral depth of the body of the astragalus; and a calcaneum that retains a large fibular facet. Although the astragalus and calcaneum co-ossify in some maniraptorans (e.g. ...
... The astragalus NMV P150070 is sister to Australovenator in both of the pruned MPTs (Fig. 2b, c). This result supports the arguments of Hocknull et al. (2009), Benson et al. (2010a, and this study (see Electronic Supplementary Material) in considering NMV P150070 a neovenatorid allosauroid, contra proposed abelisauroid affinities for this specimen (Agnolin et al. 2010). Although the results of these analyses corroborate our inclusion of NMV P221202 in Ceratosauria, we consider the hypothesized relationships of NMV P221202 within Ceratosauria to be inconclusive pending additional character support. ...
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... Yun, C.-G. -Biomechanics of megaraptoran lower jaw and manual ungual -Spanish Journal of Palaeontology 39, 2024 2 or infer their ecology and behavior (e.g., Novas et al., 2013;Bell et al., 2015;Lamanna et al., 2020). The exact phylogenetic placement of this group is still uncertain and controversial: initially, megaraptorans were interpreted to be either close to megalosauroid (=spinosauroid) tetanurans (Smith et al., 2008) or represent carcharodontosaurian allosauroids within a clade Neovenatoridae (Benson et al., 2010;Carrano et al., 2012;Zanno & Makovicky, 2013). Nowadays, megaraptorans are usually considered members of Coelurosauria (e.g., Novas et al., 2013;Porfiri et al., 2014;Aranciaga-Rolando et al., 2019, 2022a, 2022b. ...
... Indeed, a unique combination of features seen in megaraptoran forelimbs, provides additional evidence that they were adapted to hook-and-pull movements. The manus of megaraptorans is huge, and the unguals of the two medialmost manual digits (especially the first one) are enlarged and relatively narrow in width (e.g., Benson et al., 2010;White et al., 2012;Novas et al., 2013Novas et al., , 2016Aranciaga-Rolando et al., 2023). Additionally, the estimated range of motions of the forelimb bones suggest the arms of megaraptorans were very flexible, and their manual unguals were capable of hyperextension (White et al., 2015a;Aranciaga-Rolando et al., 2023). ...
Evaluating the palaeoecology of the Megaraptora (Dinosauria: Theropoda) through biomechanical approaches
Article
Full-text available
  • Nov 2024
Megaraptoran theropods represent an enigmatic and unusual lineage of theropod dinosaurs that are characterized by their unique bauplan including a low, elongated skull and robust forelimbs with enlarged claws. Such an unusual morphology has led to speculations that these theropods primarily used forelimbs instead of jaws in prey capture or feeding, but biomechanical studies regarding in-depth evaluations of the functions of their claws or jaws have been scarce. In this work, mandibular force profiles of Australian megaraptoran Australovenator wintonensis are constructed through the principle of beam theory, and mechanical advantages of first manual unguals of various megaraptoran taxa are evaluated using third-class lever model. Mandibular force profiles reveal that the lower jaw of Australovenator wintonensisbehaved as a simple lever, suitable for delivering slashing bites, and likely unable to produce a high bite force. Biomechanical modeling of the first manual unguals of megaraptorans suggests a decrease in Mechanical Advantage in derived taxa, which indicates the claws became more adapted to hook-and-pull function during the course of evolution in this clade. Such results imply megaraptorans like Australovenator wintonensis mainly preyed on relatively small-sized animals, or relied more on their forelimbs to hunt large prey items through hooking the claws onto the victim and pulling them, tearing or slicing the flesh.
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... By contrast, this is a very uncommon treat in noncoelurosaurian tetanurans, where only the megalosaurid Wiehenvenator (Rauhut et al. 2016) and the metriacanthosaurid Siamotyrannus exhibit similar condition. Despite the basal carcharodontosaurid, Concavenator has been codified as having flat ventral surface (Benson et al. 2010;Carrano et al. 2012), a recent review of its axial skeleton indicates that at least the anterior caudal vertebra have a ventral groove . In this regard the ventral surface of IPS137683 is almost flat but it possesses a very fine keel on the anterior half of the caudal centrum. ...
... Malafaia et al. 2019Chokchaloemwong et al. 2019;Coria et al. 2020;Comes da;Gomesda Costa Pereira et al. 2020). The narrow longitudinal groove in the ventral surface, bounded by faint keels in the caudal centrum is also commonly found in Abelisauroidea, Allosauroidea -especially carcharodontosauridsand Megalosauroidea (Ezcurra and Méndez 2009;Benson et al. 2010;Mateus et al. 2011;Carrano et al. 2012;Rauhut et al. 2016;Malafaia et al. 2017Malafaia et al. , 2019Coria et al. 2020). Carrano (2024) mentioned a considerable dorsoventral reduction in the caudal transverse processes of Allosauroidea, a feature that seems alto exhibit IPS137684. ...
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... Only four specimens described to date comprise associations of multiple elements: a pair of theropod pubic bones from the lower Albian Eumeralla Formation (NMV P186046: Benson et al., 2010aBenson et al., , 2010cBenson et al., , 2012Herne et al., 2010;Wagstaff et al., 2020); the megaraptorid dubbed 'Lightning Claw' (LRF 100e106) from the Cenomanian Griman Creek Formation (Bell et al., 2016; and an unnamed megaraptorid (AODF 967e968, 972, 977e979: White et al., 2020) and the holotype specimen of Australovenator wintonensis Hocknull et al., 2009 (AODF 604) from the Cenomanian Winton Formation (Hocknull et al., 2009;White et al., 2012White et al., , 2013White et al., , 2015bTucker et al., 2013). Three of these four specimens have been referred to the Megaraptoridae, the group of theropods to which the vast majority of diagnostic theropod remains in Australian mid-Cretaceous dinosaur assemblages can be referred (Benson et al., 2010bWhite et al., 2015bWhite et al., , 2020Poropat et al., 2019;Kotevski and Poropat, 2022). ...
... Tetanurae, Avetheropoda, Coelurosauria), but no further owing to their incompleteness . The presence of Neovenatoridae is possibly symptomatic of a previous nesting of Megaraptora within Neovenatoridae coupled with a cautious approach by the authors on these isolated remains (Benson et al., 2010b. More recently described specimens indicate the presence of the Megaraptoridae (Poropat et al., 2019), Noasauridae (Brougham et al., 2020) and Elaphrosaurinae in the Victorian Cretaceous. ...
A megaraptorid (Dinosauria: Theropoda) frontal from the upper Strzelecki Group (Lower Cretaceous) of Victoria, Australia
Article
  • Nov 2023
  • CRETACEOUS RES
Cretaceous (non-avian) theropod dinosaurs from Australia are poorly understood, primarily because almost all specimens described thus far comprise isolated postcranial elements. In Australia, only three non-dental cranial elements pertaining to Theropoda have been reported: the left and right dentaries of Australovenator wintonensis from the Winton Formation (Cenomanian–lowermost Turonian) of Queensland, and an isolated surangular from the Eumeralla Formation (lower Albian) of Victoria. Herein, we report the first evidence of non-mandibular cranial material of a non-avian theropod from Australia: a left frontal and fused parietal fragment from the Lower Cretaceous (lower Aptian) upper Strzelecki Group of Victoria. The specimen shares several synapomorphies with the frontals assigned to Megaraptoridae, including an anteroposteriorly elongate postorbital articulation and a truncated nasal articular surface. Accordingly, we regard this frontal as Megaraptoridae gen. et sp. indet. We performed both parsimony-based and Bayesian-based phylogenetic analyses to support our assignment, and both analyses support a placement within Megaraptoridae. However, this specimen appears to possess plesiomorphic characters relative to other megaraptorid frontals, lacking dorsoventrally high walls of bone that emarginate the nasal and prefrontal articular surfaces. The plesiomorphies of this specimen have implications for the evolution of the megaraptoran skull roof, suggesting the acquisition of specialised adaptations for longirostry over time. This specimen improves the limited record of Cretaceous Australian theropod cranial remains, and provides limited support for the hypothesis that Megaraptoridae might have originated in Australia.
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... The presence of concave surfaces adjacent to the distal carina is unusual for tyrannosauroid lateral teeth (and coelurosaurs more generally), being more typical for neovenatorid allosauroids (and the phylogenetically labile megaraptorans) . However, the typical absence of such concavities in tyrannosauroid lateral dentition is based on the assumption that Megaraptora is best interpreted as an allosauroid clade (Benson et al. 2010;Carrano et al. 2012). Recent consensus supports coelurosaurian affinities for Megaraptora, and they may be within or close to Tyrannosauroidea (Novas et al. 2013;Porfiri et al. 2014;Apestegu ıa et al. 2016;Aranciaga Rolando et al. 2019Naish & Cau 2022). ...
Theropod dinosaur diversity of the lower English Wealden: analysis of a tooth-based fauna from the Wadhurst Clay Formation (Lower Cretaceous: Valanginian) via phylogenetic, discriminant and machine learning methods
Article
Full-text available
  • Dec 2024
The Lower Cretaceous Wealden Supergroup of southern England yields a diverse assemblage of theropod dinosaurs, its taxa being represented by fragments in addition to some of the most informative associated skeletons of the European Mesozoic. Spinosaurids, neovenatorid allosauroids, tyrannosauroids and dromaeosaurids are among reported Wealden Supergroup clades. However, the majority of relevant specimens are from the Barremian Upper Weald Clay and Wessex formations, and theropod diversity in the older Berriasian–Valanginian Hastings Group has remained poorly known, the fragmentary specimens reported thus far remaining enigmatic both in terms of phylogenetic affinities and sometimes provenance. A better understanding would be welcome given the paucity of Berriasian–Valanginian dinosaurs worldwide. Here, we describe an assemblage of Hastings Group theropod teeth from the Valanginian Wadhurst Clay Formation, mostly collected from the Ashdown Brickworks locality near Bexhill, East Sussex. These teeth were assessed using phylogenetic, discriminant and machine learning analyses and were found to include members of Spinosauridae, Tyrannosauroidea and Dromaeosauridae, in addition to others that remain of uncertain affinity within Coelurosauria. The taxa appear distinct from those already known from Wealden Supergroup strata: the spinosaurid cannot be referred to Baryonyx or the tyrannosauroid to Eotyrannus, for example, but we have not named new taxa at this time. Combined with other findings in the Wadhurst Clay Formation, our study indicates that Valanginian theropod diversity was comparable to that of younger Wealden Supergroup units, implying that the ‘characteristic’ theropod components of Wealden faunas were established early in the deposition of this famous geological succession.
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... Carcharodontosauria Benson et al., 2010Carcharodontosauridae Stromer, 1931 Carcharodontosauridae gen. et sp. ...
New theropod dinosaur remains from the Upper Cretaceous of the Kem Kem Group (Eastern Morocco) clarify spinosaurid morphology
Article
  • Oct 2024
  • ZOOL J LINN SOC-LOND
The Kem Kem Group is a lowermost lithostratigraphic unit from the Upper Cretaceous that extends along the border between Algeria and Morocco, in the northern region of Africa. This geological unit has yielded several tetrapod fossils, including a well-represented assemblage of theropod dinosaurs, after more than eight decades of research. Here, we report new occurrences of spinosaurid theropods from the spinosaurine clade in the Kem Kem Group by providing anatomical descriptions and taxonomic identifications of 11 new specimens derived from the Tafilalt region of Morocco. Among the findings, we describe a cervical vertebra of Sigilmassasaurus, in addition to several cranial, axial, and appendicular elements that can safely be attributed to Spinosaurinae. Moreover, based on a unique combination of characteristics, we also describe an isolated and partial ischium belonging to an indeterminate carcharodontosaurid. We also deliver a detailed redescription of one of the most complete snouts of a spinosaurine known to date. Therefore, the theropod dinosaurs of the Kem Kem Group show considerable diversity, but many questions, especially related to the diversity of spinosaurids and the general abundance of carnivorous dinosaurs in this region, remain unclear until new materials are discovered and complete descriptions are made.
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... However, given the absence of a preserved neural arch, we cannot assign it to Baryonychinae or Spinosaurinae. CarcharodontosauriaBenson, Carrano and Brusatte, 2010 Gen. et sp. Indet. ...
A reassessment of the historical fossil findings from Bahia State Northeast Brazil reveals a diversified dinosaur fauna in the Lower Cretaceous of South America
Article
Full-text available
Supposed dinosaur remains were collected between 1859 and 1906 in the Lower Cretaceous Recôncavo Basin (Northeast Brazil). Since these materials remained undescribed, and most were considered lost. Recently, some of these historical specimens were rediscovered in the Natural History Museum of London, providing an opportunity to revisit them after 160 years. The specimens come from five different sites, corresponding to the Massacará (Berriasian-Barremian) and Ilhas (Valanginian-Barremian) groups. Identified bones comprise mainly isolated vertebral centra from ornithopods, sauropods, and theropods. Appendicular remains include a theropod pedal phalanx, humerus, and distal half of a left femur with elasmarian affinities. Despite their fragmentary nature, these specimens represent the earliest dinosaur bones discovered in South America, enhancing our understanding of the Cretaceous dinosaur faunas in Northeast Brazil. The dinosaur assemblage in the Recôncavo Basin resembles coeval units in Northeast Brazil, such as the Rio do Peixe Basin, where ornithopods coexist with sauropods and theropods. This study confirms the presence of ornithischian dinosaurs in Brazil based on osteological evidence, expanding their biogeographic and temporal range before the continental rifting between South America and Africa. Additionally, these findings reinforce the fossiliferous potential of Cretaceous deposits in Bahia State, which have been underexplored since their initial discoveries.
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... Few groups of theropods show pneumatic traits with external manifestation in their caudal vertebrae. A pleurocoel is present on the lateral surface of the centra of Megaraptora, Oviraptorosauria, Therizinosauria, and possibly Torvosaurus (e.g., Britt, 1991Britt, , 1993Zhang et al., 2001;Xu et al., 2007;Zanno et al., 2009;Benson, Carrano & Brusatte, 2010;Balanoff & Norell, 2012). However, Megaraptora is the only clade with highly pneumatized caudal vertebrae, extending to the centra and the neural arches (Coria To date, the only theropods to exhibit foramina on the dorsal surface of the caudal neural arches are Acrocanthosaurus and Meraxes (Fig. 29I), while Giganotosaurus has only shallow depressions (Britt, 1993;Aranciaga Rolando, Garcia Marsá & Novas, 2020;Canale et al., 2022). ...
Osteology of the axial skeleton of Aucasaurus garridoi: phylogenetic and paleobiological inferences
Article
Full-text available
  • Nov 2023
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.
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A new theropod dinosaur from the Callovian Balabansai Formation of Kyrgyzstan
Article
Full-text available
  • Aug 2024
Recent fieldwork in the late Middle Jurassic Balabansai Formation of Kyrgyzstan has yielded a partial skeleton of a large theropod dinosaur. The material includes a few bones of the skull (postorbital, quadratojugal), dorsal and sacral vertebrae, fragments of the pectoral girdle and forelimbs, and an almost complete pelvic girdle and hindlimbs, and is here made the type of a new theropod taxon, Alpkarakush kyrgyzicus gen. et sp. nov. Alpkarakush can be diagnosed by an extremely developed orbital brow on the postorbital, a pneumatic opening leading into cavities in the neural arch from the centroprezygodiapophyseal fossa in the posterior dorsal vertebrae, an almost enclosed ventral sulcus in manual phalanx II-1, a narrow and deep intercondylar groove on the anterior side of the distal femur, and an epicondylar crest on the distal femur that is offset from the distal end. A second, fragmentary, and smaller specimen from the same site represents the same taxon. Based on long bone histology, the type of Alpkarakush represents a late subadult individual, whereas the smaller specimen is a juvenile, possibly indicating gregarious behaviour. Phylogenetic analysis places Alpkarakush in the Metriacanthosauridae, underlining the diversity and wide distribution of this clade in the Jurassic of Asia.
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A combined approach to identify isolated theropod teeth from the Cenomanian Kem Kem Group of Morocco: cladistic, discriminant, and machine learning analyses
Article
The Kem Kem Group of Southeastern Morocco, North Africa, is well known for theropod remains, especially isolated teeth. Here, a collection of isolated theropod teeth is assessed for diversity using a combination of linear discriminant, phylogenetic, and machine learning analyses for the first time. The results confirm earlier studies on Kem Kem theropod diversity, with teeth referred to Abelisauridae, Spinosaurinae, and Carcharodontosauridae. A single tooth is ascribed to a non-abelisauroid ceratosaur or a megaraptoran and may represent the enigmatic averostran Deltadromeus. Spinosaurine teeth are clearly differentiated by all three methodologies, whereas abelisaurid and carcharodontosaurid teeth could only be distinguished by the machine learning and phylogenetic analyses. This study shows that a combination of independent methods is most effective at providing strong evidence on theropod dental diversity in a particular assemblage, and that cladistic and machine learning analyses are the most reliable approaches to identify isolated dinosaur teeth. The methodology used here is likely to yield results in other dinosaur assemblages where isolated teeth are more abundant than body fossils.
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The interrelationships and evolution of basal theropod dinosaurs
Article
Full-text available
  • Jan 2003
  • Spec Paper Palaeontology
Many recent studies of theropod relationships have been focused on the phylogeny of coelurosaurs and the question of the origin of birds, but the interrelationships and evolution of basal theropods are still poorly understood. Thus, this paper presents a phylogenetic analysis of all theropods, but focuses on the basal members of this clade. The result supports the inclusion of Eoraptor and herrerasaurids in the Theropoda, but differs from other recent studies in two main aspects: (1) The taxa usually grouped as ceratosaurs form two monophyletic clades that represent successively closer outgroups to tetanurans. The more basal of these clades, the Coelophysoidea, comprise the majority of Late Triassic and Early Jurassic theropods. The other clade of basal theropods that are usually included in the Ceratosauria comprises Ceratosaurus, Elaphrosaurus, and abelisaurids. (2) Two monophyletic groups of basal tetanurans are recognized: the Spinosauroidea and the Allosauroidea. In contrast to other recent phylogenetic hypotheses, both clades are united in a monophyletic Carnosauria. The branching pattern of the present cladogram is in general accordance with the stratigraphic occurrence of theropod taxa. Despite the differences in recent analyses, there is a significant level of consensus in theropod phylogeny. At least four different radiations of non-avian theropods can be recognized. These radiations show different patterns in Laurasia and Gondwana, and there are increasing differences between the theropod faunas of the two hemispheres from the Triassic to the Cretaceous.
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The origin and early evolution of birds
Article
  • Feb 1998
Birds evolved from and are phylogenetically recognized as members of the theropod dinosaurs; their first known member is the Late Jurassic Archaeopteryx, now represented by seven skeletons and a feather, and their closest known non-avian relatives are the dromaeosaurid theropods such as Deinonychus. Bird flight is widely thought to have evolved from the trees down, but Archaeopteryx and its outgroups show no obvious arboreal or tree-climbing characters, and its wing planform and wing loading do not resemble those of gliders. The ancestors of birds were bipedal, terrestrial, agile, cursorial and carnivorous or omnivorous. Apart from a perching foot and some skeletal fusions, a great many characters that are usually considered ‘avian’ (e.g. the furcula, the elongated forearm, the laterally flexing wrist and apparently feathers) evolved in non-avian theropods for reasons unrelated to birds or to flight. Soon after Archaeopteryx, avian features such as the pygostyle, fusion of the carpometacarpus, and elongated curved pedal claws with a reversed, fully descended and opposable hallux, indicate improved flying ability and arboreal habits. In the further evolution of birds, characters related to the flight apparatus phylogenetically preceded those related to the rest of the skeleton and skull. Mesozoic birds are more diverse and numerous than thought previously and the most diverse known group of Cretaceous birds, the Enantiornithes, was not even recognized until 1981. The vast majority of Mesozoic bird groups have no Tertiary records: Enantiornithes, Hesperornithiformes, Ichthyornithiformes and several other lineages disappeared by the end of the Cretaceous. By that time, a few Linnean ‘Orders’ of extant birds had appeared, but none of these taxa belongs to extant ‘families’, and it is not until the Paleocene or (in most cases) the Eocene that the majority of extant bird ‘Orders’ are known in the fossil record. There is no evidence for a major or mass extinction of birds at the end of the Cretaceous, nor for a sudden ‘bottleneck’ in diversity that fostered the early Tertiary origination of living bird ‘Orders’.
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The first European allosaurid dinosaur (Lower Cretaceous, Wealden Group, England)
Article
  • Nov 1996
  • Neues Jahrbuch Geol Palaontol Monatsh
Theropod dinosaurs are exceedingly rare in the Cretaceous of Europe. The substantial skeletal remains of a large theropod from the Wessex Formation (Lower Cretaceous, Barremian) of the Isle of Wight, England are described. The new specimen was a gracile allosaurid 7.5 metres in length with similarities to the North American Allosaurus and the Asian Sinraptor. Differences in the structure of the skull, the pelvic girdle and the vertebral column require a new genus (Neovenator) for this remarkably preserved dinosaur which is perhaps the most complete theropod from the European Cretaceous, comprising some 70% of the skeleton.
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Majungasaurus crenatissimus (Theropoda : Abelisauridae) from the Late Cretaceous of Madagascar - Preface
Article
  • Jun 2007
Recent fieldwork in the Upper Cretaceous (Maastrichtian) Maevarano Formation, northwest Madagascar, has yielded important new skull material of the abelisaurid theropod, Majungasaurus crenatissimus. One of these specimens in particular - a virtually complete, disarticulated, and well preserved skull - greatly elucidates the craniofacial osteology of abelisaurids. Herein we describe the skull and lower jaws of this mid-sized theropod dinosaur. A number of features of the facial skeleton and cranium (as well as the postcranium) appear to result from increased levels of mineralization and ossification, which, at least in some instances, can be related directly to specific soft-tissue structures; examples include lacrimal-postorbital contact dorsal to the orbit, suborbital processes of the lacrimal and postorbital, presence of a mineralized interorbital septum, fused interdental plates, and mineralization of the overlying integument. Autapomorphic features include a highly derived nasal - greatly thickened and fused to its counterpart, with a large interior pneumatic chamber - and a median, 'dome'-like thickening of the frontals, which appear to have been variably pneumatized by a paranasal air sac. Majungasaurus also possesses a derived suite of skull morphologies, including: a rostrocaudally abbreviated, dorsoventrally deep, and transversely broad skull; an expanded occiput, likely associated with expanded cervical musculature; short-crowned dentition; and an enlarged external mandibular fenestra consistent with a moderate degree of intramandibular movement or accommodation. A number of characters, present on both the skull and postcranial skeleton, suggest a divergent mode of predation relative to other, non-abelisaurid theropods.
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