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A new large theropod dinosaur from the Upper Jurassic of Colorado
Abstract
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... However, if a Middle Jurassic age is assumed for the African taxon Afrovenator (Sereno et al. 1994;Rauhut & López-Arbarello 2009), only few megalosaurids have been identified from the Late Jurassic. Apart from the Callovian-Oxfordian taxon Streptospondylus (Allain 2001) and the so far only preliminarily described Leshansaurus from China (Li et al. 2009), the best known Late Jurassic megalosaurid is the genus Torvosaurus, with two species, the North American Torvosaurus tanneri (Galton & Jensen 1979;Britt 1991) and the European Torvosaurus gurneyi (Hendrickx & Mateus 2014). The occurrences of Other Late Jurassic occurrences of megalosaurids are usually fragmentary, undiagnostic at species or genus level, and/or of questionable affinities (see overview in Rauhut et al. 2018). ...
... Torvosaurus is one of the most recently recognized, but at the same time one of the largest taxon of theropod from the Morrison Formation (Galton & Jensen 1979;Britt 1991). As noted by Hanson & Makovicky (2014), the genus is not only recognizable because of its large size, but also because of the massiveness of its bones, a feature that it shares with its closest relatives Megalosaurus and Wiehenvenator (Benson 2010a;Rauhut et al. 2016). ...
... Torvosaurus Galton & Jensen, 1979 Torvosaurus sp. ...
A fragmentary maxilla from the middle Callovian Ornatenton Formation of the Wiehengebirge, north-western Germany, shows two autapomorphies of the theropod dinosaur genus Torvosaurus, a maxilla fenestra that is developed as a large and shallow but not sharply defined depression and an anteroposteriorly oriented ridge transversing the ventral part of the maxillary fenestra. This specimen represents the first occurrence of this genus from Germany and the oldest record of Torvosaurus, which is otherwise securely known from the Kimmeridgian-Tithonian of Portugal and the western USA. Given that the two closest relatives of Torvosaurus, Megalosaurus and Wiehenvenator, are known from the Bathonian of England and the Callovian of Germany, respectively, an evolutionary origin of derived megalosaurines in north-central Europe is indicated. The records of Torvosaurus in the Kimmeridgian-Tithonian of Portugal and the Morrison Formation of the western USA most probably represent dispersal of the genus from this area in the Late Jurassic.
... The overall robustness and great distal expansion of this humerus exclude most dinosaur clades known from the Jurassic, such as most theropods (with the exception of Torvosaurus; Galton and Jensen, 1979), heterodontosaurids (e.g., Santa Luca, 1980;Galton, 2014), and early ornithopods (e.g., Janensch, 1955;Peng et al., 2005;Carpenter and Galton, 2018). Sauropodomorph humeri are very distinct in respect to their distal condyles (e.g., Janensch, 1961;Ostrom and McIntosh, 1966;Allain and Abbreviations: cr, ridge connecting the distal condyles; dpc, deltopectoral crest; dr, distal end of the posterolateral crest extending from the triceps tubercle distally; lc, lateral (radial) condyle; mc, medial (ulnar) condyle; oac, oblique anterior crest extending from the deltopectoral crest to the medial condyle; sr, supinator ridge. ...
... Scale bar equals 10 cm. Aquesbi, 2008), as is the case for the very robust humerus of the megalosaurid Torvosaurus (Galton and Jensen, 1979). In contrast, eurypodan thyreophorans have very short and robust humeri that are strongly expanded distally in many taxa (e.g., Gilmore, 1914;Hennig, 1925;Coombs, 1978). ...
A stegosaurian humerus from the Oxfordian–Tithonian(?) Cañadón Calcáreo Formation of Chubut, Argentina, extends the fossil record of this clade of thyreophoran ornithischian dinosaurs to the Upper Jurassic of South America. The element shares the derived character of an oblique ridge extending from the deltopectoral crest towards the medial distal condyle with taxa such as Kentrosaurus and Stegosaurus and thus represents a derived representative of the clade. The presence of stegosaurs in the Cañadón Calcáreo Formation underlines the similarities of its dinosaur fauna with other Late Jurassic dinosaur faunas, such as the Morrison Formation of North America or the Tendaguru Formation of Tanzania, in at least broad systematic terms.
... The mark with the largest striation width found on the dorsal surface of a theropod pedal claw (MWC 7263; Fig 2A) suggests denticle widths larger than any known taxon from the MMQ, but has been found in larger, non-contemporaneous taxa like Tyrannosaurus rex [45]. This measurement falls only slightly above the average denticle width of the contemporaneous Torvosaurus tanneri [58]. Hendrickx and Mateus [59] reported an average of 8 denticles per 5 mm (or 0.625 mm average denticle width using our metric) in both the European and North American Torvosaurus species. ...
... Although the taxonomic identity of OMNH 01123 has been debated as either an exceptionally large Allosaurus or a separate taxon [53,61,62], its size is generally agreed upon. Torvosaurus tanneri, with a body length of up to 10m [58], fell just below the extrapolated body sizes based on two of the ...
Bite marks provide direct evidence for trophic interactions and competition in the fossil record. However, variations in paleoecological dynamics, such as trophic relationships, feeding behavior, and food availability, govern the frequency of these traces. Theropod bite marks are particularly rare, suggesting that members of this clade might not often focus on bone as a resource, instead preferentially targeting softer tissues. Here, we present an unusually large sample of theropod bite marks from the Upper Jurassic Mygatt-Moore Quarry (MMQ). We surveyed 2,368 vertebrate fossils from MMQ in this analysis, with 684 specimens (28.885% of the sample) preserving at least one theropod bite mark. This is substantially higher than in other dinosaur-dominated assemblages, including contemporaneous localities from the Morrison Formation. Observed bite marks include punctures, scores, furrows, pits, and striations. Striated marks are particularly useful, diagnostic traces generated by the denticles of ziphodont teeth, because the spacing of these features can be used to provide minimum estimates of trace maker size. In the MMQ assemblage, most of the striations are consistent with denticles of the two largest predators known from the site: Allosaurus and Ceratosaurus. One of the bite marks suggests that a substantially larger theropod was possibly present at the site and are consistent with large theropods known from other Morrison Formation assemblages (either an unusually large Allosaurus or a separate, large-bodied taxon such as Saurophaganax or Torvosaurus). The distribution of the bite marks on skeletal elements, particularly those found on other theropods, suggest that they potentially preserve evidence of scavenging, rather than active predation. Given the relative abundances of the MMQ carnivores, partnered with the size-estimates based on the striated bite marks, the feeding trace assemblage likely preserves the first evidence of cannibalism in Allosaurus.
... The large theropods from the Morrison Formation are currently represented by five unequivocal avetheropods, namely, Ceratosaurus nasicornis (Gilmore, 1920;Madsen & Welles, 2000), Marshosaurus bicentesimus (Madsen, 1976a), Torvosaurus tanneri (Galton & Jensen, 1979;Britt, 1991), and two species of Allosaurus, A. fragilis (Madsen, 1976b) and A. jimmadseni (Chure & Loewen, 2020). Saurophaganax maximus, considered by Smith (1998) to be a junior synonym of Allosaurus, also most likely represents a different allosaurid taxon from a higher stratigraphic level of the Morrison Formation (Chure, 1995;Foster, 2020). ...
Tooth-marked bones provide important evidence for feeding choices made by extinct carnivorous animals. In the case of the dinosaurs, most bite traces are attributed to the large and robust osteophagous tyrannosaurs, but those of other large carnivores remain underreported. Here we report on an extensive survey of the literature and some fossil collections cataloging a large number of sauropod bones (68) from the Upper Jurassic Morrison Formation of the USA that bear bite traces that can be attributed to theropods. We find that such bites on large sauropods, although less common than in tyrannosaur-dominated faunas, are known in large numbers from the Morrison Formation, and that none of the observed traces showed evidence of healing. The presence of tooth wear in non-tyrannosaur theropods further shows that they were biting into bone, but it remains difficult to assign individual bite traces to theropod taxa in the presence of multiple credible candidate biters. The widespread occurrence of bite traces without evidence of perimortem bites or healed bite traces, and of theropod tooth wear in Morrison Formation taxa suggests preferential feeding by theropods on juvenile sauropods, and likely scavenging of large-sized sauropod carcasses.
... The pubic plate of P. milnerae is well-ossified as it articulates with its antimere along its entire ventral margin. Among theropods, this ventral median contact is a rarely preserved feature that has previously only been described or figured for M. rhodesiensis [60] and Torvosaurus tanneri [83]. A suture between the pubis and ilium can be clearly discerned. ...
We describe a new small-bodied coelophysoid theropod dinosaur, Pendraig milnerae gen. et sp. nov, from the Late Triassic fissure fill deposits of Pant-y-ffynnon in southern Wales. The species is represented by the holotype, consisting of an articulated pelvic girdle, sacrum and posterior dorsal vertebrae, and an associated left femur, and by two referred specimens, comprising an isolated dorsal vertebra and a partial left ischium. Our phylogenetic analysis recovers P. milnerae as a non-coelophysid coelophysoid theropod, representing the first-named unambiguous theropod from the Triassic of the UK. Recently, it has been suggested that Pant-y-ffynnon and other nearby Late Triassic to Early Jurassic fissure fill faunas might have been subjected to insular dwarfism. To test this hypothesis for P. milnerae , we performed an ancestral state reconstruction analysis of body size in early neotheropods. Although our results indicate that a reduced body size is autapomorphic for P. milnerae , some other coelophysoid taxa show a similar size reduction, and there is, therefore, ambiguous evidence to indicate that this species was subjected to dwarfism. Our analyses further indicate that, in contrast with averostran-line neotheropods, which increased in body size during the Triassic, coelophysoids underwent a small body size decrease early in their evolution.
... The bar is present in the ilia of some other theropods (e.g. Barsbold & Maryanska, 1990;Bonaparte, 1986;Galton & Jensen, 1979;Osborn, 1916), including, notably, the therizinosaur Segnosaurus (Barsbold & Perle, 1980). A similar bar is observed in Saturnalia (Langer, 2003). ...
Therizinosaurs are highly modified, probably herbivorous, theropods from the Upper Cretaceous of Asia and North America. They are characterized by an extensively pneumatized axial skeleton, and in the derived forms, an incipiently opisthopubic pelvis. The evolution of such a pelvis is expected to be associated with extensive modification of the muscular system. The muscular system is reconstructed using observed muscle scars, reconstructions of the theropods Staurikosaurus and Tyrannosaurus, the ornithischian Maiasaura, and extant crocodilians and birds. The results indicate convergence with birds and ornithischian dinosaurs, such that the retroverted pubis in some maniraptorans can be regarded as analogous with the postacetabular bar in ornithischians. Functional implications also make derived therizinosaurs, such as Nothronychus, in some respects convergent with birds as the pubis is retroverted, becoming fused with the ischium, a laterally flaring synsacrum, and an avian‐like pes.
The record of Late Jurassic stegosaur tracks from the Lourinhã Formation (Kimmeridgian-Tithonian) is here revised. Thirty-eight dinosaur tracks, preserved as natural infill casts, are here reported, and thirty-two of them are attributed to the ichnogenus Deltapodus. Four of those present impressions of skin, with polygonal scales and random pattern. Deltapodus is the most common ichnogenus in the track record of the Lourinhã Formation. The sizes and shape suggest one single dacentrurine trackmaker, which could be Miragaia longicollum, also common in the same horizons.
Spinosauridae presents an extensive geographical and temporal distribution, with records from Gondwana and Laurasia, and a temporal range from Barremian (~129 Ma, Lower Cretaceous) to Cenomanian (~95 Ma, Upper Cretaceous). To date, 13 species were described, besides several specimens identified at a broader taxonomic level. One of the most notable cranial features of spinosaurids is their elongated rostrum (hypertrophied premaxilla-maxilla). Leastwise five species possess preserved premaxillae: Angaturama limai, Baryonyx walkeri, Cristatusaurus lapparenti, Oxalaia quilombensis and Suchomimus tenerensis, besides materials tentatively attributed to Spinosaurus aegyptiacus. We studied the premaxillae shape of 10 specimens of the above-mentioned species and other materials through geometric morphometrics, reviewing diagnoses and morphological descriptions. Clear allometric and phylogenetic signals could be identified by ordination methods. We carried out a phylogenetic analysis to test spinosaurid relationships, by inclusion of new landmarks-characters from the premaxillae into a published tetanuran character-taxon matrix. The phylogenetic inference recovered C. lapparenti outside Baryonychinae, which was composed by B. walkeri and S. tenerensis. Spinosaurinae was recovered as (A. limai, (O. quilombensis, (MSNM V4047, Irritator challengeri))). Our results suggest that the premaxillae provide useful phylogenetic information and that the inclusion of landmarks-characters improves our knowledge of this enigmatic clade.
The skull-bone quadrate in nonavian theropods is very diverse morphologically alongside the disparity of the group as a whole. However this disparity has been underestimated for taxonomic purposes. In order to evaluate the phylogenetic potential and investigate the evolutionary transformations of the quadrate, we conducted a Catalano-Goloboff phylogenetic morphometric analysis as well as a cladistic analysis using 98 discrete quadrate related characters. The cladistic analysis provides a fully resolved tree mirroring to some degree the classification of nonavian theropods. The quadrate morphology by its own provides a wealth of data with strong phylogenetic signal and allows inference of major trends in the evolution of this bone. Important synapomorphies include: for Abelisauroidea, a lateral ramus extending to the ectocondyle; for Tetanurae, the absence of the lateral process; for Spinosauridae, a medial curvature of the ventral part of the pterygoid ramus occurring just above the mandibular articulation; for Avetheropoda, an anterior margin of the pterygoid flange formed by a roughly parabolic margin; and for Tyrannosauroidea, a semi-oval pterygoid flange shape in medial view. The Catalano-Goloboff phylogenetic morphometric analysis reveals two main morphotypes of the mandibular articulation of the quadrate linked to function. The first morphotype, characterized by an anteroposteriorly broad mandibular articulation with two ovoid/subcircular condyles roughly subequal in size, is found in Ceratosauria, Tyrannosauroidea and Oviraptorosauria. This morphotype allows a very weak displacement of the mandible laterally. The second morphotype is characterized by an elongate and anteroposteriorly narrow mandibular articulation and a long and parabolic/sigmoid ectocondyle. Present in Megalosauroidea, Carcharodontosauridae and Dromaeosauridae, this morphotype permits the lower jaw rami to be displaced laterally when the mouth opened.
The skull-bone quadrate in nonavian theropods is very diverse morphologically alongside the disparity of the group as a whole. However this disparity has been underestimated for taxonomic purposes. In order to evaluate the phylogenetic potential and investigate the evolutionary transformations of the quadrate, we conducted a Catalano-Goloboff phylogenetic morphometric analysis as well as a cladistic analysis using 98 discrete quadrate related characters. The cladistic analysis provides a fully resolved tree mirroring to some degree the classification of nonavian theropods. The quadrate morphology by its own provides a wealth of data with strong phylogenetic signal and allows inference of major trends in the evolution of this bone. Important synapomorphies include: for Abelisauroidea, a lateral ramus extending to the ectocondyle; for Tetanurae, the absence of the lateral process; for Spinosauridae, a medial curvature of the ventral part of the pterygoid ramus occurring just above the mandibular articulation; for Avetheropoda, an anterior margin of the pterygoid flange formed by a roughly parabolic margin; and for Tyrannosauroidea, a semi-oval pterygoid flange shape in medial view. The Catalano-Goloboff phylogenetic morphometric analysis reveals two main morphotypes of the mandibular articulation of the quadrate linked to function. The first morphotype, characterized by an anteroposteriorly broad mandibular articulation with two ovoid/subcircular condyles roughly subequal in size, is found in Ceratosauria, Tyrannosauroidea and Oviraptorosauria. This morphotype allows a very weak displacement of the mandible laterally. The second morphotype is characterized by an elongate and anteroposteriorly narrow mandibular articulation and a long and parabolic/sigmoid ectocondyle. Present in Megalosauroidea, Carcharodontosauridae and Dromaeosauridae, this morphotype permits the lower jaw rami to be displaced laterally when the mouth opened.
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