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Redescription of Gargoyleosaurus parkpinorum, a polacanthid ankylosaur from the Upper Jurassic of Albany County, Wyoming
Abstract
The polacanthid ankylosaur Gargoyleosaurus parkpinorum is described in detail for the first time. The partial skeleton indicates a small individual about 3-3.5 m long. Distinguishing features include a skull longer than wide, with laterally facing nostrils and large postorbital horns slightly overlapping onto the squamosal and a known armor pattern, as the armor was preserved in situ. Many features present in Gargoyleosaurus are also found in other polacanthids. While controversy surrounds the phylogenetic relationships amongst the polacanthids, it would appear that these taxa are closely related by the number of shared affinities.
... The mid-caudal vertebra MPCA-SM-708 ( Fig. 6F-I) is a newly identified element. It has a dorsoventrally compressed centrum slightly wider transversely than long anteroposteriorly, resembling those of Europelta (Kirkland et al. 2013) and Gargoyleosaurus (Kilbourne & Carpenter 2005). The articular surfaces seem oval, although their broken edges preclude an accurate contour identification. ...
... In this regard, the articular surface of the lateral condyle is posteriorly developed as a small prominence (tibiofibular crest; the condylid of Salgado & Coria 1996). A similar structure of the lateral condyle lying along a lateral fossa was described in Hoplitosaurus (Gilmore 1914), Nodosaurus (Lull 1921 ; Fig. 6B, C, n, notch) and Texasetes (Coombs 1995a), and is also seen in several other nodosaurids, such as Edmontonia (Burns 2015), Gargoyleosaurus (Kilbourne & Carpenter 2005), Niobrarasaurus (Carpenter et al. 1995), Polacanthus (Pereda-Suberbiola 1991), Sauropelta (Coombs 1971) and Silvisaurus (Eaton 1960). Peloroplites , Stegouros (Soto-Acuña et al. 2021), and most Ankylosauridae (Carpenter 2004;L€ u et al. 2007;Carpenter et al. 2008;Carpenter et al. 2011;Arbour & Currie 2013a) seem to lack such a compressed lateral condyle. ...
... 2E). Kilbourne & Carpenter 2005; see also Ford 2000), although sutures are only visible on the external surfaces. Striated boundaries delimit the base of the dorsal prominences (ridge or spine) of each osteoderm, and therefore flank the sutures between these. ...
The most representative ankylosaurian remains from Argentina have been found in sediments of the Allen Formation (Campanian–Maastrichtian) in Salitral Moreno, Río Negro Province. Several authors have discussed the identity and history of these remains. In this study, we review all published material along with some new remains in order to summarize all the knowledge about these ankylosaurs. Previously published material includes a tooth, dorsal and anterior caudal vertebrae, a femur and several osteoderms. The new remains include synsacral and caudal elements, a partial femur and osteoderms. The anatomy of the tooth, the synsacrum, the mid-caudal vertebra, the femur and the osteoderms, and the histology of the post-cervical osteoderms, support a nodosaurid identification, as proposed in previous descriptions of the Salitral Moreno material. Patagopelta cristata gen. et sp. nov. is a new nodosaurid ankylosaur characterized by the presence of unique cervical half-ring and femoral anatomies, including high-crested lateral osteoderms in the half rings and a strongly developed muscular crest in the anterior surface of the femur. The ∼2 m body length estimated for Patagopelta is very small for an ankylosaur, comparable with the dwarf nodosaurid Struthiosaurus. We recovered Patagopelta within Nodosaurinae, related to nodosaurids from the ‘mid’-Cretaceous of North America, contrasting the previous topologies that related this material with Panoplosaurini (Late Cretaceous North American nodosaurids). These results support a palaeobiogeographical context in which the nodosaurids from Salitral Moreno, Argentina, are part of the allochthonous fauna that migrated into South America during the late Campanian as part of the First American Biotic Interchange.
https://zoobank.org/urn:lsid:zoobank.org:pub:FBA24443-F365-49FD-A959-10D2848C2400
... The choanae are posteriorly positioned, with their preserved anterior extent roughly in line with the middle of the maxillary tooth row. This condition is similar to that seen in K. ieversi but differs from that of ankylosaurids and nodosaurids (Lee, 1996;Godefroit et al., 1999;Carpenter, 2004;Kilbourne and Carpenter, 2005;Leahey et al., 2015;Kinneer et al., 2016). ...
... Palatines-The palatines form the posteromedial margins of the choanae and are preserved mostly as impressions, with the right preserving a fragment of bone ( Figures 2C, 3B). The palatine is a thin, anteroventrally/posterodorsally angled element, similar to other ankylosaurs, such as Ankylosaurus magniventris and Gargoyleosaurus parkpinorum (Carpenter, 2004;Kilbourne and Carpenter, 2005). Together, the palatines form a U-shaped wall in posterior view that would have separated the palatal and orbital regions, similar to Pawpawsaurus campbelli (Figures 2C, 3B;Lee, 1996). ...
... To incorporate additional palatal variations noted in SAMA P40536, K. ieversi, and other ankylosaurians, we added a new character (178 in Arbour and Currie, 2016;and 190 in Soto-Acuña et al., 2021) that describes the position of the choanae within the palate relative to the maxillary tooth row: choanae with their anterior margins inline or within the anterior third of the maxillary tooth row (178/190:0); choanae posteriorly situated with their anterior margins at least mid-way along the tooth row (178/190:1). Ankylosaurians were scored from the literature (Eaton Jr, 1960;Sereno and Zhimin, 1992;Lee, 1996;Godefroit et al., 1999;Carpenter et al., 2001aCarpenter et al., , 2008Carpenter et al., , 2011Vickaryous et al., 2001;Hill et al., 2003;Carpenter, 2004;Kilbourne and Carpenter, 2005;Parsons and Parsons, 2009;Arbour and Currie, 2013;Arbour et al., 2014a;Leahey et al., 2015;Kinneer et al., 2016;Arbour and Evans, 2017;Yang et al., 2017;Bourke et al., 2018;Paulina-Carabajal et al., 2018;Wiersma and Irmis, 2018;Norman, 2020;Park et al., 2020); however, we could not adequately code the outgroup taxon Huayangosaurus taibaii because the condition of its choanae is unknown. Character polarity was therefore determined from Hesperosaurus mjosi (Maidment et al., 2018) and a 3D cranial model of Stegosaurus armatus (specimen number; UMNH VPC 44, sketchfab. ...
Australian dinosaur research has undergone a renaissance in the last 10 years, with growing knowledge of mid-Cretaceous assemblages revealing an endemic high-paleolatitude Gondwanan fauna. One of its most conspicuous members is ankylosaurs, which are rare but nonetheless occur in most Australian dinosaur-bearing formations spanning the uppermost Barremian to lower Cenomanian. Here we describe a partial ankylosaur skull from the marine Toolebuc Formation exposed near Boulia in western Queensland, Australia. This skull represents the oldest ankylosaurian material from Queensland, predating the holotype of Kunbarrasaurus ieversi, which was found in the overlying Allaru Mudstone. The ankylosaur skull is encased in a limestone concretion with the maxillary tooth rows preserved only as impressions. Synchrotron radiation X-ray tomography was used to non-destructively image and reconstruct the specimen in 3D and facilitate virtual preparation of the separate cranial bones. The reconstruction of the skull revealed the vomer, palatines, sections of the ectopterygoids and maxillae, and multiple teeth. The palate has posteriorly positioned choanae that differs from the more anterior placement seen in most other ankylosaurians, but which is shared with K. ieversi, Akainacephalus johnsoni, Cedarpelta bilbeyhallorum, Gobisaurus domoculus, and Panoplosaurus mirus. Phylogenetic analyses place the new cranial material within the recently named basal ankylosaurian clade Parankylosauria together with K. ieversi. This result, together with the anatomical similarities to the holotype of K. ieversi, permits its referral to cf. Kunbarrasaurus sp. This specimen elucidates the palatal anatomy of Australian ankylosaurs and highlights one of the most ubiquitous components of Australian mid-Cretaceous dinosaur faunas.
... (Arbour and Mallon, 2017), Borealopelta, Sauropelta (Brown et al., 2017), and Scolosaurus (Penkalski and Blows, 2013). Small-to medium-sized ankylosaurians with a body length around 3e5 m include Gargoyleosaurus (3e3.5 m) (Kilbourne and Carpenter, 2005) (Kirkland and Carpenter, 1994;Garcia and Suberbiola, 2003;Leahey et al., 2015). Thus, given the lack of information indicating the precise ontogenetic stage of the specimen, the ankylosaurian specimen from the Longjing Formation (IVPP V26052) at least represents a moderate body-sized ankylosaurian dinosaur. ...
We here report an ankylosaurian ilium from the Albian–Cenomanian Longjing Formation of Yanji City, Jilin Province, northeastern China. The diagnostic features allowing referral of this specimen to Ankylosauria include: an ilium rotated horizontally dorsal to the acetabulum with the primitive lateral surface facing ventrally; long and laterally divergent preacetabular process; and a shallow, cup-like acetabulum. This new specimen represents the first definitive ankylosaurian dinosaur from Jilin Province, and the easternmost ankylosaurian occurrence in China. The present discovery demonstrates the potential for future finds in the Longjing Formation, especially in the Longshan fossil beds of Yanji City, such as additional ankylosaurian or other dinosaur remains that might provide significant data on dinosaur evolution during the middle Cretaceous of eastern Asia.
... Both of these characters are absent in theropod and sauropodomorph dinosaurs, non-thyreophoran ornithischians and basally branching representatives of this clade, such as Scutellosaurus (Colbert, 1981) and Scelidosaurus (Norman, 2019). Although some derived ankylosaurs show a similar development of the radial condyle (e.g., Ankylosaurus; Carpenter, 2004;Euoplocephalus;Arbour and Currie, 2013), this is not the case in most taxa, including basally branching taxa, such as Myrmoorapelta (MWC 6745), Gastonia (Kinneer et al., 2016), Sauropelta (Coombs, 1978), Gargoyleosaurus (Kilbourne and Carpenter, 2005), or Cedarpelta (Carpenter et al., 2008). In stegosaurs, such an expansion is present in Huayangosaurus (Zhou, 1984), Dacentrurus (Owen, 1875;Galton, 1985;Costa and Mateus, 2019), Hesperosaurus , Kentrosaurus ( Fig. 4B; Hennig, 1925;Galton, 1982), Stegosaurus Fig. 4C; Gilmore, 1914), Loricatosaurus (Galton, 1985(Galton, , 1990, Miragaia (ML 433) and a humerus referred to Chungkingosaurus (Dong et al., 1983: fig. ...
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.
... This is indicative of body osteoderms that are located along the lateral side of the body. In polacanthine ankylosaurs, these types of osteoderms may be found along the flanks of the thoracic and lumbar regions and the lateral surfaces of the caudal region (Blows 2001, Killbourne & Carpenter 2005, Kinneer et al. 2016. In nodosaurids and ankylosaurids, they tend to be restricted to the caudal region (Burns & Currie 2014). ...
Bell, P.R., Burns, M.E. & Smith, E.T. XX.XXXX.2017. A probable ankylosaurian (Dinosauria, Thyreophora) from the Early Cretaceous of New South Wales, Australia. Alcheringa XX, xxx–xxx. ISSN 0311-5518.
We describe an isolated osteoderm from the Albian Griman Creek Formation where it is exposed near the town of Lightning Ridge in central-northern New South Wales, Australia. Several lines of evidence allow referral of this element to the Ankylosauria—a group that epitomises body armour and ubiquitous osteodermal coverage among dinosaurs. Despite the abundant record of fossil vertebrates from this interval, ankylosaurians have not been previously reported, although, they have been described from penecontemporaneous deposits in western Queensland and Victoria. This discovery, therefore, provides an important link between the northerly faunas (including the Griman Creek Formation) that flourished at the edge of the epeiric Eromanga Sea, with those from the sub-polar rift-valley system of Victoria during the mid-Cretaceous.
Phil R. Bell [pbell23@une.edu.au], School of Environmental and Rural Science, University of New England, Armidale 2351, NSW, Australia; Michael E. Burns [mburns3@jsu.edu], Department of Biology, Jacksonville State University, 700 Pelham Rd N., Jacksonville, AL 36265-2138, USA; Elizabeth T. Smith [elizabethtsmith@exemail.com.au], Australian Opal Centre, Lightning Ridge 2834, NSW, Australia.
... A synaplesiomorphy for Ankylosauria is the retention of the lateral hollow based trunk, sacral and caudal scutes of basal thyreophorans which were lost in Stegosauria, and for the Nodosauridae the presence of large lateral pectoral spines (Fig. 2B-S;thoMpsoN et al. 2012, ESM: 23-4). In all Late Jurassic nodosaurid ankylosaurs, viz., Dracopelta in Portugal (GaltoN 1983a) and for the Morrison Formation of western USA, Gargoyleosaurus and Mymoorapelta (kirklaNd et al. 1998;kilBoUrNe & carpeNter 2005), the lateral pectoral spines have hollow bases (the deep concavity extends up into the spine) with rounded edges (Fig. 2K, M), and the posterior edge is grooved to accommodate the anterior edge of the following spine (Fig. 2K). (1970) and noted that the dermal spines of Sau-ropelta "are almost identical to those of stegosaurian dinosaurs (carpeNter 1984) and without associated cranial or postcranial elements, dermal spines should therefore be regarded as Thyreophora indet." ...
In basal thyreophorans there is no equivalent to the small based slender dermal tail spines of stegosaurs, which differ in several respects from the lateral dorsal spines of nodosaurid ankylosaurs, and large based stocky spikes are restricted to a few genera of stegosaurs. Several isolated spines and spikes from England (Middle and Upper Jurassic), Portugal (Upper Jurassic) and Spain (Lower Cretaceous), previously re-identified as Thyreophora indet., are Stegosauria indet. Where available, cross-sections shows a thick layer of compact bone with a well-defined central canal as in old adult individuals of Stegosaurus (Upper Jurassic, USA) in which, in addition to display, they functioned as weapons. This stronger construction also favored their preservation as isolated bones. It contrasts with a thin layer of compact bone filled with cancellous bone for the spines of adult and younger individuals of Stegosaurus and of ankylosaurs. The preservation of an isolated pair of spines and of spikes indicates that their bases were bound together. Two columnar femora with a finger-like anterior trochanter from England (Middle and Upper Jurassic) are also re-identified as Stegosauria indet., as are the remains of a juvenile individual from Portugal (Upper Jurassic). The autapomorphies of Lori- catosaurus priscus (Nopcsa, 1911) (England, Middle Jurassic: Middle Callovian) include characters observed in the anterior and mid-caudal vertebrae, posterior pubic process and dermal armor (spine plate, small based body spine).
The early evolution of thyreophoran dinosaurs is thought to have occurred primarily in northern continents since most evidence comes from the Lower and Middle Jurassic of Europe and North America. The diversification into stegosaurs and ankylosaurs is obscured by a patchy fossil record comprising only a handful of fragmentary fossils, most with uncertain phylogenetic affinities. Here we report the discovery of a new armoured dinosaur from the early Late Cretaceous of Argentina, recovered phylogenetically using various datasets either as a basal thyreophoran or a stem ankylosaur, closely related to Scelidosaurus. It bears unusual anatomical features showing that several traits traditionally associated with the heavy Cretaceous thyreophorans did not occur universally. Jakapil kaniukura gen. et sp. nov. is the first definitive thyreophoran species from the Argentinian Patagonia. Unlike most thyreophorans, it seems to show a bipedal stance, as in Scutellosaurus. Jakapil also shows that early thyreophorans had a much broader geographic distribution than previously thought. It is a member of an ancient basal thyreophoran lineage that survived until the Late Cretaceous in South America.
The first evidence of an ankylosaur from the Late Jurassic Qigu Formation of the southern Junggar Basin (Xinjiang, northwestern China) is described, based on an isolated caudal vertebra that was discovered together with fragmentary remains of other dinosaurs, including stegosaurs, sauropods, and theropods. The caudal vertebra is characterized by the following features: (i) elliptical morphology of the centrum, being wider than high; (ii) short antero-posterior length of the centrum; (iii) pronounced transversely extending ventral groove; (iv) massive transverse process, that is longer than the centrum diameter; (v) transverse process meeting the centrum high at the dorsal half and at a relatively flat angle; (vi) transverse process making a broad contact with the neural arch without forming a proximo-dorsal projection; and (vii) notochordal prominence present in the centre of the anterior articular surface. The study specimen represents only the second record of an ankylosaur from the Jurassic of Asia – aside from the slightly older Tianchisaurus from the early Upper Jurassic Toutunhe Formation, equally from the Junggar Basin. It helps to fill a gap in our knowledge of the early evolution of these armoured dinosaurs. Additionally, this discovery highlights the potential of the southern Junggar Basin to yield a rich vertebrate fauna and thus to provide an important insight into Late Jurassic ecosystems of Central Asia.
Although the evolution and function of “exaggerated” bony projections in ornithischian dinosaurs has been subject to significant debate recently, our understanding of the structure and morphology of their epidermal keratinized coverings is greatly limited. The holotype of Borealopelta , a new nodosaurid ankylosaur, preserves osteoderms and extensive epidermal structures (dark organic residues), in anatomic position across the entire precaudal length. Contrasting previous specimens, organic epiosteodermal scales, often in the form of horn-like (keratinous) sheaths, cap and exaggerate nearly all osteoderms, allowing for morphometric and allometric analyses of both the bony osteoderms and their horny sheaths. A total of 172 osteoderms were quantified, with osteoderm spine length and height being positively allometric with respect to basal length and width. Despite tight correlations between the different measures amongst all other osteoderms, the large parascapular spines represent consistent outliers. Thickness and relative contribution of the keratinized epiosteodermal scales/sheaths varies greatly by region, ranging from 2% to 6% for posterior thoracics, to ∼25% (1.3×) for the parascapular spines—similar to horn sheaths in some bovid analogues. Relative to the bony cores, the horny portions of the spines are strongly positively allometric (slope = 2.3, CI = 1.8–2.8). Strong allometric scaling, species-specific morphology, and significant keratinous extension of the cervicoscapular spines is consistent with elaboration under socio-sexual selection. This marks the first allometric analysis of ornithischian soft tissues.
The pelvic armor elements in the ankylosaurian material from the Upper Cretaceous of Iharkút, Hungary are described here. Among these, a new articulated hip region of a small bodied ankylosaur is referred here to cf. Struthiosaurus sp. It preserves, uniquely among Late Cretaceous European ankylosaurs, an in situ pelvic armor composed of among others four, keeled, oval to circular osteoderms lying centrally and arranged longitudinally above the synsacral neural spines. This is the first indication of this type of pelvic osteoderm arrangement in an ankylosaur, increasing our knowledge on this poorly known part of the ankylosaur skeleton. Some additional pelvic osteoderms are also described that help to reconstruct and distinguish the pelvic armor of the two Late Cretaceous European ankylosaurs Struthiosaurus and Hungarosaurus. Both taxa have some fused parts in the pelvic armor but most probably neither of them had a single, fused pelvic shield as that of the Early Cretaceous Polacanthus. Interwoven texture on the ventral surface of the osteoderms, observed in both European taxa and known in other ankylosaurs (e.g. Polacanthus, Nodosaurus), is suggested here to be a characteristic feature of the non-keeled, fused pelvic armor elements of Ankylosauria.
Amongst the fossil material collected by the Sino-Soviet Expeditions (1959–1960) to the Alshan Desert, China, was a large, virtually complete ankylosaur skeleton. Gobisaurus domoculus gen. et sp. nov. closely resembles Shamosaurus scutatus, but is distinct in having an unfused basipterygoid–pterygoid contact and elongate premaxillary processes of the vomers. Although it is difficult to make a definitive taxonomic assignment without considering postcranial material, a preliminary phylogenetic analysis places Gobisaurus as the sister taxon of Shamosaurus, clustered as one of several successive outgroups of the Ankylosaurinae.Parmi le matériel fossilifère recueilli lors des expéditions sino-soviétiques (1959–1960) dans le désert d'Alshan, en Chine, se retrouvait un gros ankylosaure presque complet. Gobisaurus domoculus, n. gen. et n. sp, ressemble de près à Shamosaurus scutatus, mais il s'en distingue par le contact basiptérygoïde–ptérygoïde non soudé et des processus prémaxillaires des vomers allongés. Bien qu'il soit difficile de procéder à une affectation taxonomique définitive sans considérer le matériel postcranien, une analyse phylogénétique préliminaire définit Gobisaurus comme un taxon ayant un lien parental avec Shamosaurus, regroupé en tant qu'un de plusieurs exogroupes successifs d'Ankylosaurinae.[Traduit par la Rédaction]
A partial nodosaurid ankylosaur skeleton from Lower Cretaceous littoral deposits of Texas represents a new genus and species, Texasetes pleurohalio. It is distinguished by a prong-like scapular spine that is directed toward the innermost point of the glenoid, development of a small prespinous fossa, and retention of a splint-like fourth trochanter on the femur. Preservation in marginal marine deposits is not indicative of normal habitat preferences. T. pleurohalio is more advanced than Hoplitosaurus marshi, and the latter may be the most primitive nodosaurid for which a considerable part of the specimen is known. The proposed synonymy of Hoplitosaurus and Polacanthus is rejected.
Shanxia tianzhenensis gen. et sp. nov. is described from the Huiquanpu Formation (Upper Cretaceous) of Shanxi Province, People's Republic of China, and is characterised by the distinctive shape of the squamosal horns. Many characteristics indicate that Shanxia is an ankylosaurid ankylosaur. The discovery of Shanxia is significant for several reasons: ankylosaur specimens from China are rare; Shanxia is the most complete dinosaur yet recovered from Shanxi Province; and Shanxia is the first dinosaur to be recovered from the Huiquanpu Formation and supports the proposed Upper Cretaceous age of this unit.