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New Ornithopod from the Cedar Mountain Formation (Lower Cre- taceous) of Eastern Utah
Abstract and Figures
The first occurrence of an iguanodontian from the Lower Cretaceous Poison Strip Member of the Cedar Mountain Formation, Utah, is described and named. This new taxon is represented by a well-preserved ilium, femora, tibiae, and vertebrae, as well as other material. The fe-mora are typical for an ornithopod, but the ilium has a short, horizontal postacetabular process that is functionally an antitrochanter.
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... However, the presence or absence of this sulcus is related to individual variation in Iguanodon bernissartensis and probably in Mantellisaurus atherfieldensis [27]. Furthermore, a longitudinal ventral sulcus has been reported in other styracosternans, such as Dakotadon lakotaensis, Hypselospinus fittoni or Planicoxa venenica [20,27,35,36]. ...
Iguanodon bernissartensis is the most frequently and widely cited styracosternan ornithopod in Western Europe during the Early Cretaceous, although some of these assignments likely need to be revised to establish the true distribution of the taxon. Here, we describe a new specimen of I. bernissartensis from the upper Barremian of the Iberian Peninsula. Based on the unique combination of shared characters, the new specimen from the Arcillas de Morella Formation at Morella locality (Castellón, Spain) can be confidently referred to Iguanodon bernissartensis. These characters include parallel-sided anterior and posterior margins of the dorsal and the caudal neural spines as well as the presence of a ventral keel in the posterior dorsal centra and a broad ventral sulcus in the midline of the central surface of the most posterior sacral vertebrae. This new evidence of Iguanodon bernissartensis reinforces the knowledge about styracosternan ornithopods as the most frequently recorded dinosaur group in the Arcillas de Morella Formation.
... Two of these features-a dorsoventrally low ilium (not included in the dataset) and a triangular brevis shelf (character 331), present in Anabisetia saldiviai (see Coria and Calvo, 2002), Gasparinisaura cincosaltensis (MCS-3; Salgado et al., 1997;unpublished data, Herne, 2008), and Macrogryphosaurus gondwanicus (see Calvo et al., 2007)-were mentioned above. These features are also present in the four dryosaurids, Dryosaurus spp., Dysalotosaurus lettowvorbecki, Eousdryosaurus nanohallucis Escaso et al., 2014, andValdosaurus canaliculatus (Janensch, 1955;Galton, 1981;Escaso et al., 2014;Barrett, 2016), and also the iguanodontians Planicoxa venenica DiCroce and Carpenter, 2001 and Osmakasaurus depressus Gilmore, 1909 (Carpenter andWilson, 2008;McDonald, 2011) not included in this study. However, it is of note that the presence of a triangular brevis shelf (character 331) was not recovered as synapomorphic in any of the clades. ...
The Flat Rocks locality in the Wonthaggi Formation (Strzelecki Group) of the Gippsland Basin, southeastern Australia, hosts fossils of a late Barremian vertebrate fauna that inhabited the ancient rift between Australia and Antarctica. Known from its dentary, Qantassaurus intrepidus Rich and Vickers-Rich, 1999 has been the only dinosaur named from this locality. However, the plethora of vertebrate fossils collected from Flat Rocks suggests that further dinosaurs await discovery. From this locality, we name a new small-bodied ornithopod, Galleonosaurus dorisae n. gen. n. sp. from craniodental remains. Five ornithopodan genera are now named from Victoria. Galleonosaurus dorisae n. gen. n. sp. is known from five maxillae, from which the first description of jaw growth in an Australian dinosaur is provided. The holotype of Galleonosaurus dorisae n. gen. n. sp. is the most complete dinosaur maxilla known from Victoria. Micro-CT imagery of the holotype reveals the complex internal anatomy of the neurovascular tract and antorbital fossa. We confirm that Q. intrepidus is uniquely characterized by a deep foreshortened dentary. Two dentaries originally referred to Q. intrepidus are reassigned to Q. ? intrepidus and a further maxilla is referred to cf. Atlascopcosaurus loadsi Rich and Rich, 1989. A further ornithopod dentary morphotype is identified, more elongate than those of Q. intrepidus and Q. ? intrepidus and with three more tooth positions. This dentary might pertain to Galleonosaurus dorisae n. gen. n. sp. Phylogenetic analysis recovered Cretaceous Victorian and Argentinian nonstyracosternan ornithopods within the exclusively Gondwanan clade Elasmaria. However, the large-bodied taxon Muttaburrasaurus langdoni Bartholomai and Molnar, 1981 is hypothesised as a basal iguanodontian with closer affinities to dryomorphans than to rhabdodontids.
UUID: http://zoobank.org/4af87bb4-b687-42f3-9622-aa806a6b4116
Knowledge regarding the early evolution within the dinosaurian clade Ankylopollexia drastically increased over the past two decades, in part because of an increase in described taxa from the Early Cretaceous of North America. These advances motivated the recent completion of extensive preparation and conservation work on the holotype and only known specimen of Dakotadon lakotaensis , a basal ankylopollexian from the Lakota Formation of South Dakota. That specimen (SDSM 8656) preserves a partial skull, lower jaws, a single dorsal vertebra, and two caudal vertebrae. That new preparation work exposed several bones not included in the original description and revealed that other bones were previously misidentified. The presence of extensive deformation in areas of the skull is also noted that influenced inaccuracies in prior descriptions and reconstructions of this taxon. In addition to providing an extensive re-description of D. lakotaensis, this study reviews previously proposed diagnoses for this taxon, identifies three autapomorphies, and provides an extensive differential diagnosis. Dakotadon lakotaensis is distinct from the only other ankylopollexian taxon known from the Lakota Formation, Osmakasaurus depressus , in the presence of two prominent, anteroposteriorly oriented ridges on the ventral surfaces of the caudal vertebrae, the only overlapping material preserved between these taxa. The systematic relationships of Dakotadon lakotaensis are evaluated using both the parsimony and posterior probability optimality criteria, with both sets of analyses recovering D. lakotaensis as a non-hadrosauriform ankylopollexian that is more closely related to taxa from the early Cretaceous (e.g., Iguanacolossus , Hippodraco , and Theiophytalia ) than to more basally situated taxa from the Jurassic (e.g., Camptosaurus, Uteodon ). This taxonomic work is supplemented by field work that relocated the type locality, confirming its provenance from unit L2 (lower Fuson Member equivalent) of the Lakota Formation. Those data, combined with recently revised ages for the members of the Lakota Formation based on charophyte and ostracod biostratigraphy, constrain the age of this taxon to the late Valanginian to early Hauterivian. The only other equivalent-aged ankylopollexian taxon from North America, the poorly known Planicoxa venenica from the Poison Strip Sandstone of Utah, preserves caudal vertebrae that bear the same ventral ridges seen in D. lakotaensis , raising the possibility of a close affinity between these taxa.
Knowledge regarding the early evolution within the dinosaurian clade Ankylopollexia drastically increased over the past two decades, in part because of an increase in described taxa from the Early Cretaceous of North America. These advances motivated the recent completion of extensive preparation and conservation work on the holotype and only known specimen of Dakotadon lakotaensis , a basal ankylopollexian from the Lakota Formation of South Dakota. That specimen (SDSM 8656) preserves a partial skull, lower jaws, a single dorsal vertebra, and two caudal vertebrae. That new preparation work exposed several bones not included in the original description and revealed that other bones were previously misidentified. The presence of extensive deformation in areas of the skull is also noted that influenced inaccuracies in prior descriptions and reconstructions of this taxon. In addition to providing an extensive re-description of D. lakotaensis, this study reviews previously proposed diagnoses for this taxon, identifies two autapomorphies, and provides an extensive differential diagnosis. Dakotadon lakotaensis is distinct from the only other ankylopollexian taxon known from the Lakota Formation, Osmakasaurus depressus , in the presence of two prominent, anteroposteriorly oriented ridges on the ventral surfaces of the caudal vertebrae, the only overlapping material preserved between these taxa. The systematic relationships of D. lakotaensis are evaluated using both the parsimony and posterior probability optimality criteria, with both sets of analyses recovering D. lakotaensis as a non-hadrosauriform ankylopollexian that is more closely related to taxa from the Early Cretaceous (e.g., Iguanacolossus , Hippodraco , and Theiophytalia ) than to more basally situated taxa from the Jurassic (e.g., Camptosaurus, Uteodon ). This taxonomic work is supplemented by field work that relocated the type locality, confirming its provenance from unit L2 (lower Fuson Member equivalent) of the Lakota Formation. Those data, combined with recently revised ages for the members of the Lakota Formation based on charophyte and ostracod biostratigraphy, constrain the age of this taxon to the late Valanginian to early Barremian.
Knowledge regarding the early evolution within the dinosaurian clade Ankylopollexia drastically increased over the past two decades, in part because of an increase in described taxa from the Early Cretaceous of North America. These advances motivated the recent completion of extensive preparation and conservation work on the holotype and only known specimen of Dakotadon lakotaensis , a basal ankylopollexian from the Lakota Formation of South Dakota. That specimen (SDSM 8656) preserves a partial skull, lower jaws, a single dorsal vertebra, and two caudal vertebrae. That new preparation work exposed several bones not included in the original description and revealed that other bones were previously misidentified. The presence of extensive deformation in areas of the skull is also noted that influenced inaccuracies in prior descriptions and reconstructions of this taxon. In addition to providing an extensive re-description of D. lakotaensis, this study reviews previously proposed diagnoses for this taxon, identifies two autapomorphies, and provides an extensive differential diagnosis. Dakotadon lakotaensis is distinct from the only other ankylopollexian taxon known from the Lakota Formation, Osmakasaurus depressus , in the presence of two prominent, anteroposteriorly oriented ridges on the ventral surfaces of the caudal vertebrae, the only overlapping material preserved between these taxa. The systematic relationships of D. lakotaensis are evaluated using both the parsimony and posterior probability optimality criteria, with both sets of analyses recovering D. lakotaensis as a non-hadrosauriform ankylopollexian that is more closely related to taxa from the Early Cretaceous (e.g., Iguanacolossus , Hippodraco , and Theiophytalia ) than to more basally situated taxa from the Jurassic (e.g., Camptosaurus, Uteodon ). This taxonomic work is supplemented by field work that relocated the type locality, confirming its provenance from unit L2 (lower Fuson Member equivalent) of the Lakota Formation. Those data, combined with recently revised ages for the members of the Lakota Formation based on charophyte and ostracod biostratigraphy, constrain the age of this taxon to the late Valanginian to early Barremian.
El yacimiento Zorralbo I, situado en el municipio de Golmayo (Soria, España) perteneciente al Cretácico Inferior (Hauteriviense superior/Barremiense inferior), ha proporcionado diverso material de cuatro tipos de dinosaurios: ornitópodos, anquilosaurios (Polacanthus sp.), saurópodos (Titanosauriforme) y terópodos (Allosauroidea y Dromaeosauridae). En este trabajo se analiza el material perteneciente a un nuevo dinosaurio iguanodóntido, que presenta una serie de caracteres morfológicos y biométricos que le separan de los iguanodóntidos ya conocidos: el proceso coronoide del dentario es continuación del mismo, con el último alvéolo dentario localizándose por delante de dicho proceso; la longitud de la escápula equivale a seis veces su anchura distal y a siete veces su anchura mínima; la tuberosidad interna y el cóndilo ulnar del húmero no están alineados y el cóndilo radial se sitúa por encima del ulnar; en la ulna, el extremo distal es más ancho que el proximal y tiene forma de maza; en el radio, el extremo distal también es mazudo; el carpo está formado por tres elementos; la anchura de la muñeca equivale al 70 % de la longitud de la mano; la fórmula falangeal es 1-3-3-2-(3-4); y, por último, el prepubis es recto y el foramen obturador es abierto y queda semi-cubierto por una lengüeta ósea mesial. La suma de todos estos caracteres y las diferencias existentes entre este ejemplar y los distintos géneros de iguanodóntidos, llevan a la conclusión de que se trata de un nuevo y se propone para el mismo la denominación de Magnamanus soriaensis nov. gen. nov. sp
Although only recognized as a discrete stratigraphic unit since 1944, the Cedar Mountain Formation represents tens of millions of years of geological and biological history on the central Colorado Plateau. This field guide represents an attempt to pull together the results of recent research on the lithostratigraphy, chronostratigraphy, sequence stratigraphy, chemostratigraphy, and biostratigraphy of these medial Mesozoic strata that document the dynamic and complex geological history of this region. Additionally, these data provide a framework by which to examine the history of terrestrial faunas during the final breakup of Pangaea. In fact, the medial Mesozoic faunal record of eastern Utah should be considered a keystone in understanding the history of life across the northern hemisphere. Following a period of erosion and sediment bypass spanning the Jurassic–Cretaceous boundary, sedimentation across the quiescent Colorado Plateau began during the Early Cretaceous. Thickening of these basal Cretaceous strata across the northern Paradox Basin indicate that salt tectonics may have been the predominant control on deposition in this region leading to the local preservation of fossiliferous strata, while sediment bypass continued elsewhere. Thickening of overlying Aptian strata west across the San Rafael Swell provides direct evidence of the earliest development of a foreland basin with Sevier thrusting that postdates geochemical evidence for the initial development of a rain shadow.
A nearly complete right dentary originally noted by Mantell in 1848 is redescribed. The specimen, NHMUK 28660, was discovered in a quarry near Cuckfield, West Sussex, from the same formation as the original teeth of Iguanodon anglicus. Fresh examination reveals that NHMUK 28660 exhibits a single autapomorphy (a row of foramina extending from the ventral surface of the symphysis onto the lateral surface of the dentary) and a unique combination of characters that distinguish it from all other iguanodontian dentaries. In light of this and because I. anglicus is regarded as a nomen dubium to which additional material cannot be unambiguously referred, NHMUK 28660 is made the holotype of the new genus and species Kukufeldia tilgatensis.
Ouranosaurus nigeriensis is an iconic African dinosaur taxon that has been described on the basis of two nearly complete skeletons from the Lower Cretaceous Gadoufaoua locality of the Ténéré desert in Niger. The entire holotype and a few bones attributed to the paratype formed the basis of the original description by Taquet (1976). A mounted skeleton that appears to correspond to O. nigeriensis has been on public display since 1975, exhibited at the Natural History Museum of Venice. It was never explicitly reported whether the Venice specimen represents a paratype and therefore, the second nearly complete skeleton reported in literature or a third unreported skeleton. The purpose of this paper is to disentangle the complex history of the various skeletal remains that have been attributed to Ouranosaurus nigeriensis (aided by an unpublished field map of the paratype) and to describe in detail the osteology of the Venice skeleton. The latter includes the paratype material (found in 1970 and collected in 1972), with the exception of the left femur, the right coracoid and one manus ungual phalanx I, which were replaced with plaster copies, and (possibly) other manus phalanges. Some other elements (e.g., the first two chevrons, the right femur, the right tibia, two dorsal vertebrae and some pelvic bones) were likely added from other individual/s. The vertebral column of the paratype was articulated and provides a better reference for the vertebral count of this taxon than the holotype. Several anatomical differences are observed between the holotype and the Venice specimen. Most of them can be ascribed to intraspecific variability (individual or ontogenetic), but some are probably caused by mistakes in the preparation or assemblage of the skeletal elements in both specimens. The body length of the Venice skeleton is about 90% the linear size of the holotype. Osteohistological analysis (the first for this taxon) of some long bones, a rib and a dorsal neural spine reveals that the Venice specimen is a sub-adult; this conclusion is supported by somatic evidence of immaturity. The dorsal ‘sail’ formed by the elongated neural spines of the dorsal, sacral and proximal caudal vertebrae characterizes this taxon among ornithopods; a display role is considered to be the most probable function for this bizarre structure. Compared to the mid-1970s, new information from the Venice specimen and many iguanodontian taxa known today allowed for an improved diagnosis of O. nigeriensis.
Ankylosaurs are relatively common in the Cedar
Mountain Formation and include (1) Gastonia burgei,
(2) Sauropelta sp., and (3) Animantarx ramaljonesi new
genus, new species. Animantarx ramaljonesi is characterized
by a highly domed cranium, very small postorbital
"horns," moderately developed lateral notch in the
skull roof for the lateral temporal fenestra, indistinguishable
pattern of armor on the skull roof, small quadratojugal
"hom," elongated coracoid that is about 63% of
the scapula length, a high shoulder on the deltopectoral
crest, and an oblique ridge on anterolateral surface of the
femur below the lesser trochanter.
The Cedar Mountain ankylosaurs appear to be
restricted to distinct stratigraphic units: Gastonia burgei
to the Yellow Cat Member, Sauropelta sp. to the Poison
Strip Sandstone, and Animantarx ramaljonesi to the
Mussentuchit Member. Provisionally, such a distribution
supports a threefold division of the Cedar
Mountain dinosaur faunas. The diversity of
ankylosaurs in the Cedar Mountain is the
highest of any Lower Cretaceous formation
and may eventually provide important information
about the evolution and adaptive radiation
of these dinosaurs.
