Journal of Systematic Palaeontology最新文献

{"title":"Phylogenetic implications of the systematic reassessment of Xenacanthiformes and ‘Ctenacanthiformes’ (Chondrichthyes) neurocrania from the Carboniferous–Permian Autun Basin (France)","authors":"Vincent Luccisano, Mizuki Rambert-Natsuaki, G. Cuny, R. Amiot, J. Pouillon, Alan Pradel","doi":"10.1080/14772019.2022.2073279","DOIUrl":"https://doi.org/10.1080/14772019.2022.2073279","url":null,"abstract":"Four complete isolated neurocrania excavated during the nineteenth century in the Autun Basin (Saône-et-Loire, France) were used by Heyler & Poplin (1982) to erect two species: the symmoriiform Bibractopiscis niger and the xenacanthiform Orthacanthus commailli. However, the specimens have not been mechanically prepared and only a portion of their anatomy is available, complicating their systematic attribution. We revise their systematic status by using X-ray computed microtomography and new comparative material from the Bourbon l’Archambault Basin (Allier, France). This method allows access to the hidden anatomy of the specimens and new systematic revision: we propose O. commailli to be left in open nomenclature as ?Xenacanthimorpha. The specimens attributed to B. niger encompass two distinct morphologies: the holotype, one paratype and a neurocranium from the Bourbon l’Archambault Basin are identified as cf. Triodus sp. The last paratype is left in open nomenclature as ‘Ctenacanthiformes’ indet. We included these neurocrania in geometric morphometric and cladistic analyses of a large sample of Palaeozoic chondrichthyans. Based on the results we propose an evolutionary scenario for the neurocranial transition between the orders ‘Ctenacanthiformes’ and Xenacanthiformes. This transition mostly affects the ethmo-orbital region. The revision of the diversity of these chondrichthyan faunas calls into question potential differences in trophic structures between the different European Carboniferous–Permian basins.","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"19 1","pages":"1623 - 1642"},"PeriodicalIF":2.6,"publicationDate":"2021-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47746397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Taxonomy, phylogeny and stratigraphical ranges of middle Permian pareiasaurs from the Karoo Basin of South Africa","authors":"M. J. Van den Brandt, F. Abdala, J. Benoit, M. Day, David P. Groenewald, B. Rubidge","doi":"10.1080/14772019.2022.2035440","DOIUrl":"https://doi.org/10.1080/14772019.2022.2035440","url":null,"abstract":"Pareiasaurs were relatively abundant, globally-distributed, herbivorous parareptiles of the mid to late Permian. The basal-most forms, all members of the Bradysauria, are restricted to the Guadalupian (mid-Permian) of South Africa and went extinct in the late Capitanian near the top of the Tapinocephalus Assemblage Zone. Currently four species are recognized in this group: Bradysaurus seeleyi, B. baini, Embrithosaurus schwarzi and Nochelesaurus alexanderi. These taxa have been poorly defined historically and based on a limited number of specimens, leaving the taxonomic diversity of the group open to doubt and limiting their utility in biostratigraphy. Here, we present our fourth and final contribution to improve the understanding of this group by providing a taxonomical and phylogenetic review, updated stratigraphical ranges, and updated diagnoses for each taxon within Bradysauria. Bradysaurus seeleyi is synonymized with Bradysaurus baini, resulting in three valid mid-Permian pareiasaur taxa: Bradysaurus baini, Embrithosaurus schwarzi and Nochelesaurus alexanderi. Our cladistic analysis of cranial and postcranial characters supports the monophyly of Bradysauria with five synapomorphies. Embrithosaurus schwarzi is recovered as the sister taxon to a clade containing Bradysaurus baini and Nochelesaurus alexanderi. By identifying 157 pareiasaur specimens in fossil collections we show that the Bradysauria are stratigraphically restricted to the Abrahamskraal Formation of the Beaufort Group and suggest a staggered appearance. Bradysaurus baini is first to appear, followed by Nochelesaurus alexanderi, and lastly by Embrithosaurus schwarzi. All three taxa perished during the Capitanian mass extinction, and have their highest occurrences near the top of the Abrahamskraal Formation.","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"19 1","pages":"1367 - 1393"},"PeriodicalIF":2.6,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49575160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New Oligocene Pseudocrenilabrinae cichlid fishes (Teleostei, Cichlidae) from freshwater deposits of Libya","authors":"T. Přikryl, J. Kaur, Alison M. Murray","doi":"10.1080/14772019.2022.2033861","DOIUrl":"https://doi.org/10.1080/14772019.2022.2033861","url":null,"abstract":"Two species of fossil cichlid are described from Oligocene deposits of Libya. One is formally described as Libyachromis fugacior gen. et sp. nov. This species is considered to be the sister group to most of the remaining members of the African subfamily Pseudocrenilabrinae, perhaps close to Heterochromis, and is characterized by two predorsal bones, dorsal fin with 12–14 spines and 9–12 rays, 24–28 vertebrae, cycloid scales present on body and head including cheek, and only unicuspid teeth present on the oral and pharyngeal jaws. The second fossil form is less complete, and so we do not formally name it, but it appears to be most closely related to Tylochromis, and thus we place it in the Tylochromini. These new fossils increase our understanding of the diversity of cichlid lineages in the Palaeogene. The unnamed fossil supports the presence of Tylochromini in the Eocene and Oligocene of North Africa, as was previously suggested by the remains of partial lower pharyngeal jaws from Egypt and Libya. The named fossil adds to the known diversity of early Cenozoic cichlids that document the presence of probably Heterochromini along with Tylochromini in North Africa. http://zoobank.org/urn:lsid:zoobank.org:pub:435CD980-E4DB-4333-AB21-BDA38F9C6023","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"19 1","pages":"1343 - 1366"},"PeriodicalIF":2.6,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44978132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Re-description of the sexually dimorphic peltopleuriform fish Wushaichthys exquisitus (Middle Triassic, China): taxonomic implications and phylogenetic relationships","authors":"Chenchen Shen, G. Arratia","doi":"10.1080/14772019.2022.2029595","DOIUrl":"https://doi.org/10.1080/14772019.2022.2029595","url":null,"abstract":"Wushaichthys exquisitus, a small fish from the Ladinian of Xingyi, Guizhou Province, southern China, was named a few years ago and interpreted as the most primitive species in the Thoracopteridae (Triassic ‘flying’ fishes with a Euro-Asian distribution). However, this hypothesis was questioned, because Wushaichthys also shares features with Peltopleuridae. A detailed morphological re-description of Wushaichthys was conducted based on new specimens, plus a revision of previously studied ones, as well as of members of Peripeltopleurus and thoracopterids, and their relationships were tested with a phylogenetic analysis based on 137 characters and 54 taxa. The results suggest that Wushaichthys is a member of a clade that is interpreted here as the new superfamily Thoracopteroidea, which contains Wushaichthyidae fam. nov. (Wushaichthys + Peripeltopleurus) and Thoracopteridae and is the sister taxon of the non-monophyletic Peltopleuridae among Peltopleuriformes. Thoracopteroidea superfam. nov. is strongly supported by numerous synapomorphies (e.g. frontal (= parietal) bone slightly expanded laterally; posttemporal contacts the extrascapular anterolaterally separating it from its counterpart; suspensorium is vertically oriented; narrow and deep rectangular preopercle, vertically oriented; preopercle sutured with the rear edge of the maxilla throughout the maxillary process; enlarged pectoral fins in most genera; and deeply forked hypocercal caudal fin). Although Thoracopteridae is monophyletic, one of its genera, Thoracopterus, is not. Consequently, the content of Thoracopteridae was re-evaluated and now includes Thoracopterus, Gigantopterus, Potanichthys comb. nov. and Italopterus gen. nov. Wushaichthyidae is supported by a unique combination of characters, and the results confirm it as a thoracopteroid, but not a thoracopterid. The characters of Wushaichthys are relevant for understanding the taxonomy and systematics of thoracopteroids, especially the evolutionary morphological modifications of the pectoral and pelvic fins and the lower lobe of the caudal fin, which are some of the main characters of these fishes. http://zoobank.org/urn:lsid:zoobank.org:pub:8FFF4E8D-780C-4DFB-B0C8-7E27D912CE8E","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"19 1","pages":"1317 - 1342"},"PeriodicalIF":2.6,"publicationDate":"2021-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43575196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new, exceptionally well-preserved Permian actinopterygian fish from the Minnekahta Limestone of South Dakota, USA","authors":"Jack Stack, M. Gottfried","doi":"10.1080/14772019.2022.2036837","DOIUrl":"https://doi.org/10.1080/14772019.2022.2036837","url":null,"abstract":"The evolutionary history of Palaeozoic and early Mesozoic ray-finned fishes (Actinopterygii) is obscured by an incomplete fossil record and under-study of late Palaeozoic (Permo-Carboniferous) actinopterygians. To help address this issue, we describe a new species of ray-finned fish, Concentrilepis minnekahtaensis gen. et sp. nov., from the late early Permian (Kungurian) Minnekahta Limestone of South Dakota (USA). This taxon is represented by Field Museum of Natural History FMNH PF 3721, an exceptionally well-preserved partial three-dimensional head and trunk preserving the external anatomy and some internal elements from the skull, paired fins and scale cover. Concentrilepis is also represented by Yale Peabody Museum 18649, a laterally compressed individual that preserves the posterior portion of the body. This taxon has features of the paraphyletic ‘paleoniscoids’, including an immobile maxilla with a narrow suborbital process and a broad postorbital expansion, a heterocercal caudal fin, and rhombic ganoid scales. Concentrilepis is distinguished from similar species by the dual lateral expansions on its frontal (= parietal of sarcopterygians), the exclusion of the lacrimal from the oral margin, and lateral scales that are longer than deep and ornamented with straight, concentric ridges at their margins and diagonal ridges at their centres. We conducted a maximum parsimony analysis in PAUP and a Bayesian analysis with the Mkv model in MrBayes with 73 other taxa and 222 characters that placed this taxon in a polytomy with other late Palaeozoic and early Mesozoic ‘paleoniscoids’. We also found that the application of Bayesian and parsimony techniques in tandem provided the necessary caution in interpreting our results and focused direction for future study. Continued efforts to gather more morphological data from ‘paleoniscoids’ in concert with the development and testing of novel phylogenetic characters and inference techniques will be necessary to improve our understanding of the interrelationships of late Palaeozoic and early Mesozoic actinopterygians. http://zoobank.org/urn:lsid:zoobank.org:pub:9F12F99D-A33A-41C2-AC34-F4936786020B","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"19 1","pages":"1271 - 1302"},"PeriodicalIF":2.6,"publicationDate":"2021-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42372934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new dipnoan genus from the Middle Devonian of Huize, Yunnan, China","authors":"Yanchao Luo, Xindong Cui, Tuo Qiao, Min Zhu","doi":"10.1080/14772019.2022.2042409","DOIUrl":"https://doi.org/10.1080/14772019.2022.2042409","url":null,"abstract":"A new genus and species of tooth-plated lungfishes, Dianodipterus huizeensis gen. et sp. nov., is described from the Qujing Formation (late Eifelian, Middle Devonian) of Huize County, Qujing, north-eastern Yunnan, China. It differs from other lungfishes in the small proportion of the tooth-bearing part on the pterygoid (less than one-quarter), the extensively developed anteromedial edentulous portion of the pterygoid, and tooth rows few in number (only four). Phylogenetic analysis reveals that Dianodipterus is more plesiomorphic than Dipterus, yet crownward of Melanognathus. As the ninth Devonian lungfish genus from China, the new taxon displays a novel schema of lungfish dentition and increases the diversity of early lungfishes. http://zoobank.org/urn:lsid:zoobank.org:pub:207B0E6E-EBBF-4E92-83F4-78FDAD6EBB60","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"19 1","pages":"1303 - 1315"},"PeriodicalIF":2.6,"publicationDate":"2021-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44822993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The most complete extinct species of Testudo (Testudines, Testudinidae) defined by several well-preserved skeletons from the late Miocene of Romania","authors":"A. Pérez‐García, M. Martín-Jiménez, E. Vlachos, V. Codrea","doi":"10.1080/14772019.2022.2028025","DOIUrl":"https://doi.org/10.1080/14772019.2022.2028025","url":null,"abstract":"The genus Testudo was considered, for more than two centuries, to group almost all tortoises that are part of current biodiversity (i.e. the members of Testudinidae), as well as the extinct representatives of that successful lineage. However, only three extant species, as well as scarce late Miocene to late Pliocene extinct ones, are now considered attributable to that genus. The fossil record of the extinct representatives is restricted to postcranial elements. They correspond almost exclusively to shells or partial shells, most of the species being known on the basis of only one individual. Abundant material of testudinids from the late Miocene of eastern Romania (Crețești 1 fossil site, Vaslui County) is presented here. This material is attributable to Testudo, representing a new species. This find is not only relevant for the abundance of specimens, but they stand out for their unusually good preservation. Most of them are represented by partial skeletons, preserving not only several bones in anatomical connection but also some regions of the peculiar ossified dermal armour that covered their limbs. Two of these skeletons preserve the skull, which allows us to perform both the first three-dimensional reconstruction of the cranial anatomy and the first neuroanatomical study of an extinct member of Testudo. The best-preserved extinct species of the reference genus of the only extant lineage of tortoises (i.e. Testudinidae), Testudo lohanica sp. nov., is characterized in detail.","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"19 1","pages":"1237 - 1270"},"PeriodicalIF":2.6,"publicationDate":"2021-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47171272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new cyprinid from the Oligocene of Qaidam Basin, north-eastern Tibetan plateau, and its implications","authors":"Tao Yang, Weiyu Liang, Jiahao Cai, H. Gu, Lei Han, Hongyu Chen, Haojian Wang, Lin Bao, De-Fei Yan","doi":"10.1080/14772019.2021.2015470","DOIUrl":"https://doi.org/10.1080/14772019.2021.2015470","url":null,"abstract":"The Qaidam Basin, lying in the north-eastern Tibetan Plateau, China, is key to understanding the Cenozoic climatic and biological changes that have occurred on the plateau; however, information from a palaeontological perspective on this Palaeogene basin is scant. Recently, fossil cyprinids were found in the middle portion of the Shangganchaigou Formation (= Upper Ganchaigou Formation; Oligocene) in the north-western Qaidam Basin. These share many osteological characters with barbines and ‘morphologically primitive clade schizothoracines’ (= primitive schizothoracines; i.e. Schizothorax and Aspiorhynchus), and they closely resemble the latter in the size and shape of the scales: body scales are small and oval; the number of lateral line scales exceeds 100; and the long-oval scales from the pre-anal region are very similar to the ‘anal scales’, which are unique to schizothoracines. Compared with another fossil fish, Paleoschizothorax qaidamensis, from the same formation, the major differences are: (1) the posterior part of the entopterygoid in the new material is normal and not expanded while that of P. qaidamensis is obviously expanded; and (2) the premaxilla process of maxilla is well developed in P. qaidamensis but weak in the new specimens. Therefore, they are described as a new species of the fossil genus Paleoschizothorax (subfamily Schizothoracinae): Paleoschizothorax diluculum sp. nov. A phylogenetic analysis, which included 13 extant genera and three fossil forms of barbines and schizothoracines and 70 morphological characters, also supports the close relationship between P. diluculum and primitive schizothoracines. A preliminary correlation analysis suggests that the degree of reduction of body scale size is negatively correlated with habitat mean temperatures among most Chinese cyprinids. Moreover, we speculate that the ‘primitive schizothoracines’ likely originated in the north-eastern–central Tibetan Plateau based on the fossil records and molecular phylogeny of the extant taxa. http://zoobank.org/urn:lsid:zoobank.org:pub:C461C7C0-9BAB-44DD-8DEE-0B5BB03D6479","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"19 1","pages":"1161 - 1182"},"PeriodicalIF":2.6,"publicationDate":"2021-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49189749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new hadrosaurid (Dinosauria: Ornithischia) from the Late Cretaceous of northern Patagonia and the radiation of South American hadrosaurids","authors":"S. Rozadilla, Federico Brissón-Egli, F. Agnolín, A. Aranciaga-Rolando, F. Novas","doi":"10.1080/14772019.2021.2020917","DOIUrl":"https://doi.org/10.1080/14772019.2021.2020917","url":null,"abstract":"Here we describe a new hadrosaurid from the Upper Cretaceous (Campanian–Maastrichtian) Allen Formation of Río Negro Province, north-west Patagonia. The new taxon is based on cranial and postcranial elements from subadult and adult specimens. The new taxon may have reached 8–9 m in total body length, and it is diagnosed by a unique combination of characters, including a very low maxilla with respect to the dentary, and a dentary with a prominent and elongate anterior process with a deep groove on its anterior end, among other features. The new taxon is known from well-preserved elements and constitutes one of the most complete hadrosaurids known from South America. Features of the teeth, cranial and postcranial bones of the new taxon overlap with those of other hadrosaurid specimens previously recorded from this continent. This new evidence allows us to recognize that Secernosaurus koerneri, Bonapartesaurus rionegrensis and ‘Kritosaurus’ australis are valid taxa. The latter can be distinguished from the other South American taxa, as well as from Kritosaurus from North America. Thus, a new generic name is proposed for the species ‘Kritosaurus’ australis. Phylogenetic analysis recovers a new clade of South American hadrosaurids composed of the new taxon, ‘Kritosaurus’ australis, Bonapartesaurus and Secernosaurus. The new South American clade is tentatively nested among Kritosaurini and is supported by several traits, including an ilium with a subhorizontal ridge separating the preacetabular notch from the pubic pedicle, a longitudinal ridge on the dorsal surface of the postacetabular process, and a twisted distal end of the postacetabular process. The recovery of a monophyletic clade of South American hadrosaurids indicates that the history of the clade on Gondwanan landmasses is far from well understood, and new discoveries may change the current picture of the taxonomy and phylogenetic relationships of southern duck-billed dinosaurs. http://zoobank.org/urn:lsid:zoobank.org:pub:6C6F0056-9D3A-4097-A10E-2E33C9DB76B9","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"19 1","pages":"1207 - 1235"},"PeriodicalIF":2.6,"publicationDate":"2021-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47220742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing conflict between early neornithischian tree topologies","authors":"Emily E. Brown, R. Butler, P. Barrett, S. Maidment","doi":"10.1080/14772019.2022.2032433","DOIUrl":"https://doi.org/10.1080/14772019.2022.2032433","url":null,"abstract":"The phylogenetic relationships of the species commonly referred to as ‘hypsilophodontids’ remain one of the key questions in ornithischian dinosaur research, having profound implications for understanding the origin, evolution and taxonomical compositions of several more recently evolved neornithischian clades. Recent phylogenetic analyses have recovered two conflicting placements for these taxa: (1) primarily within Cerapoda (Ornithopoda + Marginocephalia), as a paraphyletic assemblage of early ornithopods; and (2) primarily outside of Cerapoda, within the clade Thescelosauridae. Here we assess three recent independent neornithischian phylogenetic studies that have recovered topologies congruent with one of these placements. We compare the compositions of these data matrices and test how each of them responds to manipulation of taxa and characters. The positions in which controversial clades are recovered is shown to be highly dependent on the sample of taxa analysed; however, taxon incompleteness or instability is not a contributing factor in altering topology. Character completeness and homoplasy is shown not to significantly alter tree topology either, although these factors can affect resolution. In one matrix investigated, femoral and dental characters are found to provide disproportionate support for the placement of key taxa outside of Cerapoda, and the exclusion of a small number of these characters results in ‘hypsilophodontids’ falling within Ornithopoda. In contrast, matrices that originally recovered ‘hypsilophodontids’ within Cerapoda are comparably more stable, with this array of taxa remaining in a consistent position throughout all analyses. There is still much work to be done to resolve these relationships, but our study provides several suggestions for future analyses with the aim of resolving areas of conflict within the neornithischian tree.","PeriodicalId":50028,"journal":{"name":"Journal of Systematic Palaeontology","volume":"19 1","pages":"1183 - 1206"},"PeriodicalIF":2.6,"publicationDate":"2021-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47340636","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}