A new alvarezsaurian theropod from the Upper Jurassic Shishugou Formation of western China

Qin, Zichuan; Clark, James M.; Choiniere, Jonah N.; Xu, Xing

doi:10.1038/s41598-019-48148-7

Cited by 30 publications

(29 citation statements)

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“…Kellner & Tomida, 2000; Kellner, 2015), and theropods (including birds) may co‐ossify carpals with metacarpals (e.g. Min et al ., 2014; Xu & Qin, 2017; Navalón et al ., 2018; Qin et al ., 2019) or with other carpals (e.g. Barta, Nesbitt & Norell, 2018).…”

Section: Methods Of Assessing Maturitymentioning

confidence: 99%

“…Tumarkin‐Deratzian, 2009; Min et al ., 2014; Depalma et al ., 2015). Confusingly, sometimes smooth textures are only used to interpret that the individual is simply not a hatchling (Qin et al ., 2019), and in one instance a smooth bone surface texture was taken as evidence that the individual was a ‘juvenile’ (Pereda Suberbiola & Barrett, 1999). Porous vertebral texture has also been used to diagnose immaturity in spinosaurid theropods, although this remains to be tested as thoroughly as in long bones (Lakin & Longrich, 2019).…”

Section: Methods Of Assessing Maturitymentioning

confidence: 99%

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Assessing ontogenetic maturity in extinct saurian reptiles

et al. 2020

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Morphology forms the most fundamental level of data in vertebrate palaeontology because it is through interpretations of morphology that taxa are identified, creating the basis for broad evolutionary and palaeobiological hypotheses. Assessing maturity is one of the most basic aspects of morphological interpretation and provides the means to study the evolution of ontogenetic changes, population structure and palaeoecology, life‐history strategies, and heterochrony along evolutionary lineages that would otherwise be lost to time. Saurian reptiles (the least‐inclusive clade containing Lepidosauria and Archosauria) have remained an incredibly diverse, numerous, and disparate clade through their ~260‐million‐year history. Because of the great disparity in this group, assessing maturity of saurian reptiles is difficult, fraught with methodological and terminological ambiguity. We compiled a novel database of literature, assembling >900 individual instances of saurian maturity assessment, to examine critically how saurian maturity has been diagnosed. We review the often inexact and inconsistent terminology used in saurian maturity assessment (e.g. ‘juvenile’, ‘mature’) and provide routes for better clarity and cross‐study coherence. We describe the various methods that have been used to assess maturity in every major saurian group, integrating data from both extant and extinct taxa to give a full account of the current state of the field and providing method‐specific pitfalls, best practices, and fruitful directions for future research. We recommend that a new standard subsection, ‘Ontogenetic Assessment’, be added to the Systematic Palaeontology portions of descriptive studies to provide explicit ontogenetic diagnoses with clear criteria. Because the utility of different ontogenetic criteria is highly subclade dependent among saurians, even for widely used methods (e.g. neurocentral suture fusion), we recommend that phylogenetic context, preferably in the form of a phylogenetic bracket, be used to justify the use of a maturity assessment method. Different methods should be used in conjunction as independent lines of evidence when assessing maturity, instead of an ontogenetic diagnosis resting entirely on a single criterion, which is common in the literature. Critically, there is a need for data from extant taxa with well‐represented growth series to be integrated with the fossil record to ground maturity assessments of extinct taxa in well‐constrained, empirically tested methods.

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Section: Methods Of Assessing Maturitymentioning

confidence: 99%

Section: Methods Of Assessing Maturitymentioning

confidence: 99%

Assessing ontogenetic maturity in extinct saurian reptiles

et al. 2020

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“…The upper section of the Shishugou Formation (here referred as the "upper" Shishugou Formation), which includes the upper part of the middle beds and the upper beds ( Fig. 1A), is the richest taxonomically, with a dozen dinosaur species recorded to date (Currie and Zhao 1993;Eberth et al 2010;Choiniere et al 2014aChoiniere et al , 2014bQin et al 2019). The fauna is dominated by herbivorous dinosaurs belonging to five clades ( Fig.…”

Section: Introductionmentioning

confidence: 99%

“…(C) Left part of cranium and mandible, dentary teeth, and right quadrate and quadratojugal. Silhouettes are based on the reconstructions of Cisiopurple (Aorun, Hualianceratops, Bellusaurus, Jiangjunosaurus), Scott Hartman (Guanlong, Mamenchisaurus), Gregory S. Paul (Yangchuanosaurus for Sinraptor), Choiniere et al (2010a;Zuolong), Choiniere et al (2010b;Haplocheirus), Wang et al (2016;Limusaurus), Qin et al (2019;Shishugounykus), Megalotitan (Tienshanosaurus), and Ornithischophilia (Yinlong). [Colour online.]…”

Section: Introductionmentioning

confidence: 99%

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Dental anatomy of the apex predator Sinraptor dongi (Theropoda: Allosauroidea) from the Late Jurassic of China

et al. 2020

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The dental morphology of the holotype of the theropod Sinraptor dongi from the Jurassic Shishugou Formation of China is comprehensively described. We highlight a combination of dental features that appear to be restricted to Sinraptor: (i) crowns with denticulated mesial and distal carinae extending from the root and an irregular surface texture on the enamel; (ii) a D-to salinon-shaped cross-sectional outline at the crown base in mesialmost teeth; (iii) mesial crowns with mesial carinae spiraling mesiolingually and lingually positioned longitudinal groove adjacent to the mesial carina; and (iv) particularly labiolingually compressed lateral teeth with weakly labially deflected distal carinae, flat to concave basocentral surfaces of the labial margins of the crowns, and horizontally elongated distal denticles showing short to well-developed interdenticular sulci. Using cladistic, multivariate, discriminant, and cluster analyses, we demonstrate that the dentition of Sinraptor is relatively similar to that of ceratosaurids, megalosauroids, and other allosauroids and is particularly close to that of Allosaurus. The dental anatomy of Sinraptor and Allosaurus, which differs mainly in the labiolingual compression of the lateral crowns and in the number of premaxillary teeth, shows adaptations towards a predatory lifestyle, including premaxillary teeth capable of enduring tooth-tobone contact and crowns with widely separated mesial and distal carinae capable of inflicting widely open wounds.Résumé : La morphologie dentaire de l'holotype du théropode Sinraptor dongi de la Formation jurassique de Shishugou, en Chine, est décrite de manière exhaustive. Nous soulignons une combinaison de caractères dentaires qui semblent être exclusifs à Sinraptor, dont (i) des couronnes présentant des carènes mésiales et distales s'étendant jusqu'à la racine, et une texture de l'émail irrégulière, (ii) une section transversale de la base de la couronne des dents les plus mésiales en forme de D ou de salinon, (iii) des carènes mésiales des couronnes mésiales spiralant mésiolingualement et un sillon longitudinal adjacent à la carène mésiale sur la surface linguale et (iv) des dents latérales particulièrement comprimées labiolingualement présentant des carènes distales faiblement déviées labialement, des surfaces basocentrales plates à concaves des marges labiales des couronnes et des denticules distaux allongés horizontalement montrant des sulcus interdenticulaires courts à bien développés. En utilisant des analyses cladistiques, multivariées, discriminantes et typologiques, nous démontrons que la dentition de Sinraptor est assez semblable à celle des cératosauridés, des mégalosauroïdes et d'autres allosauroïdes, et est particulièrement proche de celle d'Allosaurus. L'anatomie dentaire de Sinraptor et d'Allosaurus, dont la principale différence est la compression labiolinguale des couronnes latérales et le nombre de dents prémaxillaires, présente des adaptations à un mode de vie prédateur, dont des dents prémaxillaires résistantes aux contac...

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The forelimbs of Alvarezsauroidea (Dinosauria: Theropoda): Insight from evolutionary teratology

Guinard¹

2022

Journal of Morphology

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Alvarezsauroidea (Tetanurae) are nonavian theropod dinosaurs whose forelimb evolution is characterised by the overdevelopment of digit I, at the expense of the other two digits, complemented by a drastic forelimb shortening in derived species (Parvicursorinae). These variations are recognised as evolutionary developmental anomalies. Evolutionary teratology hence leads to a double diagnosis with (1) macrodactyly of digit I and microdactyly of digits II and III, plus (2) anterior micromelia. The teratological macrodactyly/microdactyly coupling evolved first.Developmental mechanisms disturbing limb proportion are thought to be convergent with those of other Tetanurae (Tyrannosauridae, Carcharodontosauridae). As for the manual anomalies, both are specific to Alvarezsauroidea (macrodactyly/ microdactyly) and inherited (digit loss/reduction). While considering the frame-shift theory, posterior digits develop before the most anterior ones. There would therefore be a decrease in the area devoted to digits II (condensation 3) and III (condensation 4), in connection with the Shh signalling pathway, interacting with other molecular players such as the GLI3 protein and the Hox system. Developmental independence of digit I (condensation 2) would contribute to generating a particular morphology. Macrodactyly would be linked to a variation in Hoxd-13, impacting Gli3 activity, and increasing cell proliferation. The loss/reduction of digital ray/phalanges (digits II and III), would be associated with Shh activity, a mechanism inherited from the theropodan ancestry. The macrodactyly/microdactyly coupling, and then anterior micromelia, fundamentally changed the forelimb mechanical function, compared to the 'classical' grasping structure of basal representatives and other theropods. The distal ossification of the macrodactylian digit has been identified as physiological, implying the use of the structure. However, the debate on a particular 'adaptive' use is pointless as the ecology of an organism is interactively complex, being both at the scale of the individual and dependent on circumstances. Other anatomical features also allow for compensation and different predation (cursorial hindlimbs).

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A new alvarezsaurian theropod from the Upper Jurassic Shishugou Formation of western China

Cited by 30 publications

References 50 publications

Assessing ontogenetic maturity in extinct saurian reptiles

Assessing ontogenetic maturity in extinct saurian reptiles

Dental anatomy of the apex predator Sinraptor dongi (Theropoda: Allosauroidea) from the Late Jurassic of China

The forelimbs of Alvarezsauroidea (Dinosauria: Theropoda): Insight from evolutionary teratology

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