Vertebrate Anatomy Morphology Palaeontology最新文献

{"title":"Computed tomographic investigation of a hatchling skull reveals ontogenetic changes in the dentition and occlusal surface morphology of Hadrosauridae (Dinosauria: Ornithischia)","authors":"Trystan Warnock-Juteau, Michael Ryan, Tim Patterson, Jordan Mallon","doi":"10.18435/vamp29395","DOIUrl":"https://doi.org/10.18435/vamp29395","url":null,"abstract":"CMN 8917 is a small, partial skull of a duck-billed dinosaur from the upper Campanian DinosaurPark Formation in what is now Dinosaur Provincial Park, Alberta. It represents one of the few nestling-sized juvenile hadrosaurines known to date. Support for this phylogenetic placement includes a narial vestibule not enclosed within the premaxillary dorsal and lateral processes, the presence of an anterodorsal maxillary process, and a maxillary dorsal process that is longer anteroposteriorly than dorsoventrally. The skull also possesses tooth traits traditionally associated with lambeosaurines, such as secondary ridges on some maxillary and dentary tooth crowns, and denticulation on some maxillary tooth crowns. The occurrence of these features in a juvenile hadrosaurine suggests that they were modified during ontogeny, calling into question their taxonomic utility for identifying juvenile specimens. The dentary teeth of CMN 8917 are similar to those of many adult hadrosaurids in that they possess a concave occlusal surface with steeper lingual and shallower buccal wear zones. This differs from the occlusal surface morphology present in some other juvenile hadrosaurids, which suggests interspecific differences in dental battery development—possibly reflective of dietary differences—occurred during early ontogeny in some taxa.","PeriodicalId":256887,"journal":{"name":"Vertebrate Anatomy Morphology Palaeontology","volume":"50 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140665645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new armored dinosaur with double cheek horns from the early Late Cretaceous of southeastern China","authors":"L. Xing, Kecheng Niu, Jordan C. Mallon, Tetsuto Miyashita","doi":"10.18435/vamp29396","DOIUrl":"https://doi.org/10.18435/vamp29396","url":null,"abstract":"Ankylosaurines are the iconic armoured dinosaurs that characterize terrestrial vertebrate faunas in the Late Cretaceous of Asia and Laramidia (western North America). The earliest members of this clade are known from the early Late Cretaceous (Cenomanian–Santonian) times of Asia, but little consensus has emerged as to how they are related to the anatomically derived and chronologically younger forms. In southeastern China, the Cretaceous red sand beds crop out across basins from Zhejiang to Guandong provinces. However, the horizons corresponding to the early Late Cretaceous stages remain poorly sampled. Here, we report the first definitive vertebrate skeleton ¾ let alone that of an armoured dinosaur ¾ from the Coniacian/Turonian Ganzhou Formation, Datai yinliangis gen. et sp. nov. Despite the immature ontogenetic status of the type materials, D. yingliangis can be diagnosed with autapomorphic traits in the cranial caputegulae (such as double horns on the quadratojugal) and extensive gular osteoderms. Morphologically, it is intermediate between the chronologically older ankylosaurids from Asia (e.g., Crichtonpelta and Jinyunpelta) and derived post-Cenomanian ankylosaurines (e.g., Pinacosaurus). Phylogenetic analyses broadly corroborate this assessment. The new taxon either falls in the grade of Asian ankylosaurines proximal to the lineages of derived forms or forms a sister lineage to Pinacosaurus. Based on these insights, Datai makes a significant addition to the early Late Cretaceous vertebrate fauna from southeastern China and highlights the future potential in this region for improved understanding of the origin and early evolution of ankylosaurines.","PeriodicalId":256887,"journal":{"name":"Vertebrate Anatomy Morphology Palaeontology","volume":"91 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139959754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hemigrammopetersius barnardi (Teleostei: Characiformes: Alestidae): a study of skeletal ontogeny and identification of homology for phylogenetic analysis","authors":"Meghan Dueck, Alison Murray","doi":"10.18435/vamp29393","DOIUrl":"https://doi.org/10.18435/vamp29393","url":null,"abstract":"Members of Alestidae, a family of characiforms found in sub–Saharan Africa, have a wide range ofadult body sizes. Because of this range of adult size, phylogenetic characters for the group may be difficult to distinguish from ontogenetic features, resulting in groups being united based on body size rather than evolutionary relatedness. Although previous studies have presented the morphology and osteology of some small and miniature taxa, these were pre–cladistic and did not attempt to distinguish between phylogenetic and ontogenetic features. Here we provide a study on the external morphology and osteology of a small alestid, Hemigrammopetersius barnardi which has reductions and losses of osteological features. We compared this species to juveniles of Alestes dentex, an alestid that attains much larger adult size, to identify characters in H. barnardi that potentially result from a decrease in body size rather than shared ancestry. We found that the loss of particular bones of the circumorbital series and postcranium, as well as a reduction of the sensory canal system, are likely the result of small body size, and therefore are not useful in establishing phylogenetic relationships among alestids.","PeriodicalId":256887,"journal":{"name":"Vertebrate Anatomy Morphology Palaeontology","volume":"10 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139609915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The biomechanical significance of bifurcated cervical ribs in apatosaurine sauropods","authors":"Matthew J Wedel, Mike Taylor","doi":"10.18435/vamp29394","DOIUrl":"https://doi.org/10.18435/vamp29394","url":null,"abstract":"Bifurcated cervical ribs have evolved infrequently in dinosaurs. Previously documented examples include those in abelisaurid theropods, leptoceratopsid ceratopsians, and turiasaurian sauropods. In apatosaurine sauropods a spectrum of cervical rib morphologies exists, from cervical ribs with small dorsal processes extending from the shafts to completely bifurcated cervical ribs. Similar dorsal processes are present in the dicraeosaurid Dicraeosaurus. The presence of dorsal processes and bifurcated cervical ribs suggests that the hypaxial neck muscles that inserted on the cervical ribs were oriented in divergent directions. In all the dinosaurian examples we have found, the cervical ribs are maximally bifurcated in the middle of the cervical series. We hypothesize that bifurcated cervical ribs are traces of diverging neck muscles that provided improved control in the middle of the neck, at some distance from both the head and the trunk.","PeriodicalId":256887,"journal":{"name":"Vertebrate Anatomy Morphology Palaeontology","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139235882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Morphological variation in the first vertebra among acanthomorph fishes – a guide for identifying fossil centra from microvertebrate sites","authors":"Alison M. Murray, D. Brinkman","doi":"10.18435/vamp29392","DOIUrl":"https://doi.org/10.18435/vamp29392","url":null,"abstract":"Innumerable fossil fish specimens have been recovered from fossil microvertebrate sites – areas in which small, isolated elements of the skeleton from multiple individuals have been amassed. The accumulated skeletal remains, often the result of transportation by moving waters, provide an important window on the fauna that was present in a wider area during a broader period of time than that represented by individual articulated specimens. Although microvertebrate localities provide important records of taxa, the disarticulated condition of the fossil elements can cause difficulties for taxonomic identification. This is particularly true for fish, which are most commonly represented in microfossil sites by vertebral centra; however, fish centra are notoriously difficult to identify at lower taxonomic levels, partly because of the vast numbers of living fish and lack of comparative collections. Arguably, the most distinctive vertebral centrum among all fish is the first abdominal centrum of Acanthomorpha. In acanthomorphs, in contrast to all other fishes, the first centrum bears two distinct (separate left and right) facets for articulation with the exoccipitals, which are normally positioned more or less dorsolateral to the articular facet for the basioccipital, forming a unique tri-partite morphology. We here document the first centrum of numerous acanthomorph fishes, and assess the morphologies for taxonomic or phylogenetic consistencies that would allow us to identify isolated centra to a particular acanthomorph group. Features we document include: whether the neural arch is fused to the centrum (as in the paracanthopterygians Lota lota and Percopsis omiscomaycus) or autogenous (most acanthopterygians); whether the left and right facets for the exoccipitals meet in the midline (e.g., Boops boops) or are widely separated (e.g., percids and scorpaenids); and the bone texture on the centrum which may be an anastomosed network forming many small spaces (e.g., Scomber spp.) or a more solid network with no spaces (e.g., Channidae), among others. From our examination of specimens, we note several unique features among the taxa examined: the first centrum of Monopterus alba is opisthocoelus and the first neural arch has processes extending posteriorly; the first centrum of Leiognathus equula has ventral process extending from the facets for articulation with the exoccipitals; there are anterior accessory processes on the neural arch of Parachanna obscura; the transverse processes of Chlorurus sp. and Scarus vetula extend from the ventral area of the centrum and form long triangular processes; and the neural arch of Siganus guttatus has ventrolateral processes that extend to the level of the ventral surface of the centrum. We also find that the overall morphology of the first centrum is conservative within a family, indicating that in many cases fossil material may be identified at least to the family level.","PeriodicalId":256887,"journal":{"name":"Vertebrate Anatomy Morphology Palaeontology","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127958839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Canadian Society of Vertebrate Palaeontology Annual Meeting Abstracts 2023","authors":"Alison M. Murray, R. B. Holmes, M. Powers","doi":"10.18435/vamp29391","DOIUrl":"https://doi.org/10.18435/vamp29391","url":null,"abstract":"<jats:p>n/a</jats:p>","PeriodicalId":256887,"journal":{"name":"Vertebrate Anatomy Morphology Palaeontology","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122887385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Variation in the shell elements of Chrysemys picta bellii (Gray 1831)","authors":"Joseph A. Corsini","doi":"10.18435/vamp29390","DOIUrl":"https://doi.org/10.18435/vamp29390","url":null,"abstract":"Variation in the Shell Elements of Chrysemys picta bellii (Gray 1831) \u0000Assignment of fossil turtle shell elements to a specific taxon is often difficult because the range of variation within the population is usually not well characterized. In addition, it is sometimes not clear whether the fossil forms actually differ from their extant counterparts because often the range of shell element variation in modern species has not been determined. The emydid turtles are no exception, with confusion often arising in the identification of isolated fossil elements and sometimes intact shells representing Emys, Pseudemys, Malaclemys, and Graptemys, as well as the deirochelyids Chrysemys,  Clemmys, Deirochelys, and Trachemys. In order to begin providing a database with modern counterparts of the deirochelyid turtles, I have photographed and illustrated seven extant Chrysemys picta bellii shells, six of which were collected at a single pond in Nebraska and one from Ladd Marsh in Union County, Oregon . Photographs and detailed illustrations indicate a broad range in the shapes of many characters.  Side by side comparisons of some key elements show that there is significant variation in several important characters (nuchal shape/sulci, entoplastron shape/sulci, and pygal shape/sulci). I also conducted a limited morphometric analysis of several sulcus/suture distance ratios, showing substantial variation between individuals in some cases. Covariance and correlation analysis of this variation suggests that allometry is not involved in most cases. In summary, this work provides a visual and morphometric dataset for aid in identifying and assigning shell elements of fossil emydid turtles.","PeriodicalId":256887,"journal":{"name":"Vertebrate Anatomy Morphology Palaeontology","volume":"17 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120928417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Problematic putative pachycephalosaurids: Synchrotron µCT imaging shines new light on the anatomy and taxonomic validity of Gravitholus albertae from the Belly River Group (Campanian) of Alberta, Canada","authors":"Aaron Dyer, M. Powers, Phiip Currie","doi":"10.18435/vamp29388","DOIUrl":"https://doi.org/10.18435/vamp29388","url":null,"abstract":"The taxonomic validity of the holotype and sole specimen of the pachycephalosaurid Gravitholus albertae (TMP 1972.027.0001) from the Belly River Group (Alberta, Canada), remains unresolved forty years after its first description. The diagnosis for this species is tenuous at best and extensive cranial fusion has prevented a thorough description and taxonomic referral of TMP 1972.027.0001. We used synchrotron µCT imaging to identify fused sutures and segment the individual elements that comprise TMP 1972.027.0001. This allowed for a detailed description of the specimen in a more thorough comparative framework with other known pachycephalosaurid specimens. Using new observations of contacts between cranial elements, the morphological distinction of TMP 1972.027.0001 from other Belly River Group pachycephalosaurids was tested with bivariate and multivariate morphometric analyses. TMP 1972.027.0001 is morphologically consistent as an end-stage semaphorant of Stegoceras validum. Furthermore, we find no taxonomically significant morphometric distinctions between Gravitholus albertae, Hanssuesia sternbergi, and Stegoceras validum, and propose the former two are synonymous with the later. Large Stegoceras validum frontoparietals show statistically significant dimorphism in the thickness of the frontonasal boss, which is not apparent amongst juvenile and subadult specimens. Pathologies consistent with intraspecific combat (“headbutting”) appear restricted to frontoparietal domes with proportionally taller frontonasal bosses, and suggests that the two morphs represent sexual dimorphs, rather than separate species. Foraminacephale brevis and Stegoceras validum are the only named pachycephalosaurids recognised in the Dinosaur Park Formation. The stratigraphic and temporal range of Stegoceras validum is extended into the underlying Oldman Formation. Pachycephalosaurid diversity in the Campanian is reduced as a result of these revised taxonomic hypotheses. A revised phylogenetic character matrix, recognising taxonomic synonymies and ontogenetically dependent character states results in a largely unresolved Pachycephalosauria.","PeriodicalId":256887,"journal":{"name":"Vertebrate Anatomy Morphology Palaeontology","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116959464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Consilient evidence affirms expansive stabilizing ligaments in the tyrannosaurid foot","authors":"Lara Surring, Michael E Burns, E. Snively, Daniel E. Barta, T. Holtz, A. Russell, L. Witmer, P. Currie","doi":"10.18435/vamp29387","DOIUrl":"https://doi.org/10.18435/vamp29387","url":null,"abstract":"Tyrannosaurid dinosaurs were ecologically unique vertebrates as the sole clade of large terrestrial carnivores (adults >400 kg) in their continent-spanning habitats. Expanded ligaments between metatarsals, inferred by gross morphology of attachment correlates, have been hypothesized to have strengthened their specialized arctometatarsus. We tested the hypothesis of ligament presence with scanning electron microscopy and histological thin sections of putative attachment sites in a third metatarsal of the tyrannosaurid Gorgosaurus libratus, compared with a thin section from the unspecialized metatarsals of the early theropod Coelophysis bauri. In the Gorgosaurus metatarsal, Sharpey´s fibers and rough, pitted surface textures consistent with ligament coalescence occur at expansive distal regions and localized rugosities are ideally located for resisting torsional loading on the foot. Sparser Sharpey’s fibers occur at expected locations in other arctometatarsus-bearing coelurosaurs. In contrast, the Coelophysis metatarsal lacked Sharpey’s fibers or rugosity at the sectioned location, acting as a definitive negative control for identifying these features in tyrannosaurids. With soft-tissue correlates confirmed as ligament entheses, we conclude that tyrannosaurids possessed distinctive and specific ligament attachments to the third metatarsal lacking in other large carnivorous dinosaurs. Histological evidence for extensive distal intermetatarsal ligaments is consistent with greater inferred agility in derived tyrannosaurid dinosaurs than in earlier lineages of large theropods.","PeriodicalId":256887,"journal":{"name":"Vertebrate Anatomy Morphology Palaeontology","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116964497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CSVP abstracts 2022","authors":"Alison Murray, Kirstin Brink, R. Holmes","doi":"10.18435/vamp29386","DOIUrl":"https://doi.org/10.18435/vamp29386","url":null,"abstract":"<jats:p>n/a</jats:p>","PeriodicalId":256887,"journal":{"name":"Vertebrate Anatomy Morphology Palaeontology","volume":"2010 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127347553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}