Ontogeny and variation of a protoceratopsid dinosaur <i>Bagaceratops rozhdestvenskyi</i> from the Late Cretaceous of the Gobi Desert

Czepiński, Łukasz

doi:10.1080/08912963.2019.1593404

Cited by 14 publications

(6 citation statements)

References 52 publications

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“…However, the count of functional teeth in the largest individual (IVPP V18637) is at least 14. Hence, the number of the maxillary teeth may increase with the ontogeny of Y. downsi , as in Psittacosaurus mongoliensis and Protoceratops ( Brown and Schlaikjer, 1940 ; Sereno et al, 1990 ; Czepiński, 2019 ). In large individuals (IVPP V18637, IVPP V14530), there is 1 replacement tooth out of 14 or 13 functional teeth in the maxilla whereas smaller specimens (IVPP V18637, IVPP V18638) have a higher ratio of the replacement teeth to the functional teeth such as 2 RT/8 FT and 3 RT/10 FT ( Table 1 ).…”

Section: Discussionmentioning

confidence: 99%

Computed tomographic analysis of the dental system of three Jurassic ceratopsians and implications for the evolution of tooth replacement pattern and diet in early-diverging ceratopsians

Forster

et al. 2022

eLife

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The dental system of ceratopsids is among the most specialized structure in Dinosauria by the presence of tooth batteries and high-angled wear surfaces. However, the origin of this unique dental system is poorly understood due to a lack of relative knowledge in early-diverging ceratopsians. Here we study the dental system of three earliest-diverging Chinese ceratopsians: Yinlong and Hualianceratops from the early Late Jurassic of Xinjiang and Chaoyangsaurus from the Late Jurassic of Liaoning Province. By micro-computed tomographic analyses, our study has revealed significant new information regarding the dental system, including no more than five replacement teeth in each jaw quadrant; at most one replacement tooth in each alveolus; nearly full resorption of the functional tooth root; and occlusion with low-angled, concave wear facets. Yinlong displays an increase in the number of maxillary alveoli and a decrease in the number of replacement teeth during ontogeny as well as the retention of functional tooth remnants in the largest individual. Chaoyangsaurus and Hualianceratops have slightly more replacement teeth than Yinlong. In general, early-diverging ceratopsians display a relatively slow tooth replacement rate and likely use gastroliths to triturate foodstuffs. The difference in dietary strategy might have influenced the tooth replacement pattern in later-diverging ceratopsians.

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Section: Discussionmentioning

confidence: 99%

Computed tomographic analysis of the dental system of three Jurassic ceratopsians and implications for the evolution of tooth replacement pattern and diet in early-diverging ceratopsians

Forster

et al. 2022

eLife

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“…The absence of a sagittal crest in individuals of the marginocephalian Psittacosaurus (Coombs, 1982) and the early‐diverging ornithischian Lesothosaurus (Knoll, 2002) similarly contributed to ‘juvenile’ diagnoses. Young protoceratopsid individuals have also been distinguished by the location of the antorbital fossa, a straight frontonasal suture, and the elements forming the supratemporal fenestra (Czepiński, 2019). Ontogenetic changes in tyrannosaurid cranial morphology, including the morphology of the sagittal crest, the antorbital fossa, the surangular shelf, and cross‐sectional nasal shape, have been described in detail (e.g.…”

Section: Methods Of Assessing Maturitymentioning

confidence: 99%

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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“…Composition. Under the primary reference phylogeny, Protoceratopsidae comprises Bagaceratops rozhdestvenskyi , Magnirostris dodsoni (?= Bagaceratops rozhdestvenskyi ; see Czepiński, 2020 ), and Protoceratops spp.…”

Section: Phylogenetic Nomenclature Of Ornithischian Cladesmentioning

confidence: 99%

The phylogenetic nomenclature of ornithischian dinosaurs

Madzia

Arbour

Boyd

et al. 2021

PeerJ

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Ornithischians form a large clade of globally distributed Mesozoic dinosaurs, and represent one of their three major radiations. Throughout their evolutionary history, exceeding 134 million years, ornithischians evolved considerable morphological disparity, expressed especially through the cranial and osteodermal features of their most distinguishable representatives. The nearly two-century-long research history on ornithischians has resulted in the recognition of numerous diverse lineages, many of which have been named. Following the formative publications establishing the theoretical foundation of phylogenetic nomenclature throughout the 1980s and 1990s, many of the proposed names of ornithischian clades were provided with phylogenetic definitions. Some of these definitions have proven useful and have not been changed, beyond the way they were formulated, since their introduction. Some names, however, have multiple definitions, making their application ambiguous. Recent implementation of the International Code of Phylogenetic Nomenclature (ICPN, or PhyloCode) offers the opportunity to explore the utility of previously proposed definitions of established taxon names. Since the Articles of the ICPN are not to be applied retroactively, all phylogenetic definitions published prior to its implementation remain informal (and ineffective) in the light of the Code. Here, we revise the nomenclature of ornithischian dinosaur clades; we revisit 76 preexisting ornithischian clade names, review their recent and historical use, and formally establish their phylogenetic definitions. Additionally, we introduce five new clade names: two for robustly supported clades of later-diverging hadrosaurids and ceratopsians, one uniting heterodontosaurids and genasaurs, and two for clades of nodosaurids. Our study marks a key step towards a formal phylogenetic nomenclature of ornithischian dinosaurs.

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Ontogeny and variation of a protoceratopsid dinosaur Bagaceratops rozhdestvenskyi from the Late Cretaceous of the Gobi Desert

Cited by 14 publications

References 52 publications

Computed tomographic analysis of the dental system of three Jurassic ceratopsians and implications for the evolution of tooth replacement pattern and diet in early-diverging ceratopsians

Computed tomographic analysis of the dental system of three Jurassic ceratopsians and implications for the evolution of tooth replacement pattern and diet in early-diverging ceratopsians

Assessing ontogenetic maturity in extinct saurian reptiles

The phylogenetic nomenclature of ornithischian dinosaurs

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