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22. Phylogenetic relationships of Oryctodromeus and other neornithischians. A, inset of consensus tree from Boyd (2015, Fig. 2) showing recovered relationships of Orodrominae and related taxa. B, Bayesian consensus tree recovered in this analysis using forty-eight taxa and additional characters for Oryctodromeus using a revised matrix of Boyd (2015).
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... The Wayan Formation of eastern Idaho and the Vaughn Member of the Blackleaf Formation in southwestern Montana are coeval geological units in a single sedimentary basin (Krumenacker, 2020). Oryctodromeus cubicularis, from the Wayan Formation and Vaughn Member, is the most completely known North American Cenomanian dinosaur taxon north of the Mussentuchit assemblage (Krumenacker, 2010(Krumenacker, , 2017Krumenacker et al., 2017Krumenacker et al., , 2019Varricchio et al., 2007). Orodromines, as defined by Brown et al. (2013), share characteristics that include a sacropubal articulation, a sharp scapular spine, and a D-shaped cross-section of the fibula. ...
... This discovery provided the first evidence of burrowing and denning behavior among non-avian dinosaurs, and evidence for parental care in this taxon. Additional work on Oryctodromeus includes an analysis of the forelimb and pectoral girdle (Fearon & Varricchio, 2016); reports of new specimens from additional localities in the Vaughn Member and discovery of the taxon in the Wayan Formation of southeastern Idaho (Krumenacker, 2010(Krumenacker, , 2017Krumenacker et al., 2017;Krumenacker et al., 2019) and a report on the taphonomy of additional specimens found in burrows in Idaho and Montana (Krumenacker et al., 2019). These new specimens, together with the holotype (MOR 1636a) and paratype (MOR 1636b), represent all skeletal elements with the exception of the sternals, and some cranial and manual elements. ...
The vertebrate assemblages of the Albian to Cenomanian Wayan Formation of southeastern Idaho and southwestern Montana’s coeval Vaughn Member of the Blackleaf Formation are dominated by the small, burrowing orodromine dinosaur Oryctodromeus cubicularis. Here, we describe in detail the osteology of Oryctodromeus based on new specimens from Idaho and Montana that add substantially to the preliminary description of the types from Montana, and provide a suite of additional diagnostic characters for the taxon: ilium with elongate preacetabular process; elongate cervical vertebra centra with an anteroposterior length 1.6 times the dorsoventral height; elongate dorsal vertebra centra with an anteroposterior length 1.4 times the dorsoventral height; more than 55 elongate caudal vertebrae enveloped in hypaxial and epaxial ossified tendons; and a femoral head on an elongate neck—similar to that of Koreanosaurus—projecting from the greater trochanter at about 35°. The tail, comprising two-thirds of the animal’s roughly 3 meters length, and associated tendon sheaths in the axial column indicate greater flexibility than previously supposed for ossified tendons or, alternatively, suggest that the Oryctodromeus burrows had separate, or multiple entrances and exits. The elongated and angled femoral head likely facilitated digging via a braced splayed-leg posture. Our phylogenetic analysis incorporates new characteristics and supports the monophyly of Orodrominae, a clade of neornithischian dinosaurs from the middle to Late Cretaceous of Asia and western North America that utilized burrowing.
... This condition resembles the morphology found in thescelosaurids and ornithopods (e.g. Krumenacker 2017;Madzia et al. 2018). In addition, the anterior surface exhibits remarkable anterior linea intermuscularis and several striae, which could be associated with M. femorotibialis. ...
... In this respect, Tietasaura derbyiana is similar to the morphology found in thescelosaurids and ornithopods (e.g. Krumenacker 2017). ...
Supposed dinosaur remains were collected between 1859 and 1906 in the Lower Cretaceous Recôncavo Basin (Northeast Brazil). Since these materials remained undescribed, and most were considered lost. Recently, some of these historical specimens were rediscovered in the Natural History Museum of London, providing an opportunity to revisit them after 160 years. The specimens come from five different sites, corresponding to the Massacará (Berriasian-Barremian) and Ilhas (Valanginian-Barremian) groups. Identified bones comprise mainly isolated vertebral centra from ornithopods, sauropods, and theropods. Appendicular remains include a theropod pedal phalanx, humerus, and distal half of a left femur with elasmarian affinities. Despite their fragmentary nature, these specimens represent the earliest dinosaur bones discovered in South America, enhancing our understanding of the Cretaceous dinosaur faunas in Northeast Brazil. The dinosaur assemblage in the Recôncavo Basin resembles coeval units in Northeast Brazil, such as the Rio do Peixe Basin, where ornithopods coexist with sauropods and theropods. This study confirms the presence of ornithischian dinosaurs in Brazil based on osteological evidence, expanding their biogeographic and temporal range before the continental rifting between South America and Africa. Additionally, these findings reinforce the fossiliferous potential of Cretaceous deposits in Bahia State, which have been underexplored since their initial discoveries.
... b the complicated relationships of what was formerly referred to as the "hypsilophodonts" (i.e., Boyd et al. 2009, Brown et al. 2013, Boyd 2015. During mid-Cretaceous time there are several well documented members of Orodrominae documented from western North America: Zephyrosaurus (Sues 1980) from the Aptian Cloverly Formation and Oryctodromeus (Varricchio et al. 2007, Krumenacker 2017 from the Cenomanian Wayan and Blackleaf formations (Fig. 1). However, the fossil record of Thescelosaurinae in North America is absent until the Maastrichtian (Boyd et al. 2009, Eberth et al. 2013. ...
... A prominent, deep notch, indicative of the thescelosaurine-grade condition (as figured in Gilmore 1915 for the type of Thescelosaurus) separates the lesser from the greater trochanter. This deep intertrochanteric notch is not present in the femora of orodromines (Scheetz 1999, Varricchio et al. 2007, Huh et al. 2010, Krumenacker 2017). The intertrochanteric notch in Nevadadromeus schmitti is more developed than in the contemporaneous Chinese thescelosaurine Changchunsaurus parvus (Butler et al. 2011) or in the thescelosaurines, Notohypsilophodon or Thescelosaurus (Gilmore 1915, Ibiricu et al. 2014. ...
... Although N. schmitti is only represented by a partial skeleton, the very unique anatomy of the femora justifies a new taxonomic designation. The prominent intertrochanteric notch between the greater and lesser trochanters is not seen in any other basal neornithischian from North America of Cenomanian age (Krumenacker 2017). The depocenter of the Willow Tank Basin represents one of the most southwestern units of the Sevier Foreland Basin during the Late Cretaceous. ...
In 2008, and subsequent collecting trips, the remains of a partial basal neornithischian were recovered from the Cenomanian Willow Tank Formation of southern Nevada. Bones identified include the proximal femora, a series of vertebrae missing neural arches, several pedal phalanges, fragments of ossified tendons, and some as yet unidentified elements. Size and shape of the femora are consistent with other known basal neornithischians of both orodromine- and thescelosaurine-grade. The round femoral head exhibits a convex anterior side but a concave posterior surface. The neck beneath the head projects proximodorsally at an obtuse angle (~100°) from the femoral shaft. The greater trochanter sits slightly posterior to and offset from the neck of the femoral head. Anterior and lateral to the greater trochanter is a pointed lesser trochanter. The three-sided lesser trochanter bows slightly posterior toward the greater trochanter. A
prominent and deep notch separates the lesser from the greater trochanter and is characteristic of thescelosaurine-grade ornithischians. This deep intertrochanteric notch is absent in the femora of orodromines. A raised but taphonomically truncated base on the posterior femoral diaphysis likely represents the remnants of a pendant fourth trochanter. The vertebrae of the Nevada basal neornithischian are similar to both thescelosaurine- and orodromine-grade morphology. The laterally biconcave vertebrae are asymmetrical in having a boss on the posteroventral end of the centrum. The centra are nearly twice as long as they are tall with the oval articular surfaces, taller than they are wide. Due to the very fragmentary nature of this specimen, parsimonious phylogenetic analysis yields statistically insignificant results. Nevertheless, a few taxonomically important characters, particularly those of the femur, support the hypothesis that this is a
thescelosaurine, and a new genus and species, herein referred to as Nevadadromeus schmitti gen. et sp. nov. This would represent the earliest occurrence of thescelosaurines in the fossil record of North America as all other thescelosaurines from the continent date to the Maastrichtian. The geographic position of the Willow Tank Formation depocenter, very proximal to the Sevier highlands of the time, likely experienced some biogeographic insularity from other areas represented by contemporaneous units of western North America, e.g., Mussentuchit Member of the Cedar Mountain Formation of Utah, the Wayan Formation of Idaho, and the Blackleaf Formation of Montana.
... The Wayan Formation dominantly consists of poorly exposed variegated mudstones and siltstones, with subordinate coarsegrained lithologies such as those of the Robison Bonebed (Dorr, 1985;Weishampel et al., 2002;Krumenacker, 2010Krumenacker, , 2017. The approximate stratigraphic interval of the Robison Bonebed is shown, as well as radiometric dates recovered from certain stratigraphic horizons (data from Dorr, 1985;Krumenacker, 2010;Krumenacker et al., 2016;Ross et al., 2017). ...
... In addition, the Wayan tyrannosauroid adds to the limited but growing knowledge of the faunal composition of the WVA. The most common vertebrate taxon within the WVA is the neornithischian Oryctodromeus cubicularis (Krumenacker, 2017(Krumenacker, , 2019Krumenacker et al., 2019). The assemblage also comprises many other as yet poorly represented taxa (Dorr, 1985;Weishempal et al., 2002;Krumenacker, 2010Krumenacker, , 2019Krumenacker et al., 2016). ...
The diversity of mid-Cretaceous tyrannosauroids is poorly understood. We describe a partial tyrannosauroid femur from the Albian–Cenomanian Wayan Formation of eastern Idaho that helps to fill in an important spatiotemporal gap in the North American record of tyrannosaurs. This specimen, consisting of the proximal half of the bone, is morphologically similar to the femur of Moros intrepidus , a small-bodied tyrannosauroid from the Cenomanian Mussentuchit Member of the Cedar Mountain Formation of Utah, but not referable to this taxon. The Wayan femur lacks an autapomorphy diagnostic for Moros intrepidus , indicating the presence of a previously unrecognized tyrannosauroid taxon in the early Late Cretaceous of Laramidia. Histological results indicate that, at the time of death, this individual was at least five years old, skeletally immature, and undergoing growth at a moderate rate. The addition of this tyrannosauroid to the Wayan-Vaughn Assemblage provides additional evidence for the widespread distribution of various tyrannosauroid taxa in Laramidia during the early Late Cretaceous.
... Besides Changmiania liaoningensis, we have integrated 14 taxa that were not included in Dieudonné et al. (2016) data-matrix: Ankylosauria, Archaeoceratops oshimai, Chaoyangsaurus youngi, Goyocephale lattimorei, Homalocephale calathocercos, Isaberrysaura mollensis, Kulindadromeus zabaikalicus, Laquintasaura venezuelae, Liaoceratops yanzigouensis, Morrosaurus antarcticus, Stegosauria, Stenopelix valdensis, Thescelosaurus assiniboiensis and Wannanosaurus yansiensis. In the present analysis, we have not coded the basal ornithopod Oryctodromeus cubicularis, from the middle Cretaceous Blackleaf Formation of southwestern Montana and the Wayan Formation of southeastern Idaho, USA (Varricchio, Martin & Katsura, 2007;Krumenacker, 2010Krumenacker, , 2017, pending the formal publication of the numerous partial skeletons from the Wayan Formation (Krumenacker, 2010(Krumenacker, , 2017. The final analysis consequently includes 61 taxonomic units and 263 characters (Table S1 provides the character descriptions, Table S2 contains the final data matrix, Table S3, the data matrix in TNT format, and Table S4, the character support for selected nodes). ...
... Besides Changmiania liaoningensis, we have integrated 14 taxa that were not included in Dieudonné et al. (2016) data-matrix: Ankylosauria, Archaeoceratops oshimai, Chaoyangsaurus youngi, Goyocephale lattimorei, Homalocephale calathocercos, Isaberrysaura mollensis, Kulindadromeus zabaikalicus, Laquintasaura venezuelae, Liaoceratops yanzigouensis, Morrosaurus antarcticus, Stegosauria, Stenopelix valdensis, Thescelosaurus assiniboiensis and Wannanosaurus yansiensis. In the present analysis, we have not coded the basal ornithopod Oryctodromeus cubicularis, from the middle Cretaceous Blackleaf Formation of southwestern Montana and the Wayan Formation of southeastern Idaho, USA (Varricchio, Martin & Katsura, 2007;Krumenacker, 2010Krumenacker, , 2017, pending the formal publication of the numerous partial skeletons from the Wayan Formation (Krumenacker, 2010(Krumenacker, , 2017. The final analysis consequently includes 61 taxonomic units and 263 characters (Table S1 provides the character descriptions, Table S2 contains the final data matrix, Table S3, the data matrix in TNT format, and Table S4, the character support for selected nodes). ...
... The longest cervical is cervical 3; then, there is apparently a slight decrease in length until cervical 6, as also noticed in Changchunsaurus (Butler et al., 2011). The cervical centra appear less elongated than in Oryctodromeus (Krumenacker, 2017). The lateral surfaces of the centra are concave both anteroposteriorly and dorsoventrally. ...
A new basal ornithopod dinosaur, based on two nearly complete articulated skeletons, is reported from the Lujiatun Beds (Yixian Fm, Lower Cretaceous) of western Liaoning Province (China). Some of the diagnostic features of Changmiania liaoningensis nov. gen., nov. sp. are tentatively interpreted as adaptations to a fossorial behavior, including: fused premaxillae; nasal laterally expanded, overhanging the maxilla; shortened neck formed by only six cervical vertebrae; neural spines of the sacral vertebrae completely fused together, forming a craniocaudally-elongated continuous bar; fused scapulocoracoid with prominent scapular spine; and paired ilia symmetrically inclined dorsomedially, partially covering the sacrum in dorsal view. A phylogenetic analysis places Changmiania liaoningensis as the most basal ornithopod dinosaur described so far. It is tentatively hypothesized that both Changmiania liaoningensis specimens were suddenly entrapped in a collapsed underground burrow while they were resting, which would explain their perfect lifelike postures and the complete absence of weathering and scavenging traces. However, further behavioural inference remains problematic, because those specimens lack extensive sedimentological and taphonomic data, as it is also the case for most specimens collected in the Lujiatun Beds so far.
... In both the Wayan Formation and the Vaughn Member, associated and/or articulated elements occur densely concentrated. These concentrations are typified by the co-occurring holotype (MOR 1636a) and paratypes (MOR 1636b), which, based on size and histological analysis, represent one presumably sexually mature (MOR 1636a) and at least two juvenile (MOR 1636b) individuals (Krumenacker, 2017). Hereafter these two specimens are referred to as MOR 1636. ...
... This same study suggests that this sort of pattern typifies that of terrestrial Mesozoic fossil assemblages. The estimated weight of the largest known Oryctodromeus specimen, based on femoral circumference, is 28 kg (Krumenacker, 2017), putting Oryctodromeus far below the threshold shown for preferential preservation in the Dinosaur Park Formation and presumably similar alluvial systems. Preferential destruction of remains of smaller vertebrate taxa within typical terrestrial Mesozoic depositional systems is suggested to be due to processes such as scavenging, bioturbation, and other chemical and physical processes (Behrensmeyer et al., 1979). ...
... The type locality of Oryctodromeus is a rare instance of body and trace fossils of one dinosaur taxon preserved together, with evidence for behavior, ecology, and reproduction strategies, making it a crucial site to document and preserve in its entirety. Work on the taphonomy and occurrence of Oryctodromeus from the Wayan Formation of Idaho indicates that Oryctodromeus is the single most common dinosaur faunal member of the ecosystems in which it occurs (Krumenacker et al. 2016;Krumenacker 2017). The models presented here are therefore additionally intended to assist in identification and diagnosis of future discoveries of Oryctodromeus burrows and serve as comparative tools for documenting the range of morphology and geological context of additional burrows. ...
Oryctodromeus cubicularis is a small-bodied ornithischian dinosaur from the mid-Cretaceous Blackleaf and Wayan Formations of Montana and Idaho, respectively, and is the only documented dinosaur with evidence of a burrowing ecology. The type locality, from the Blackleaf Formation of southwestern Montana, consisted of an infilled burrow structure containing the disarticulated skeletons of one adult and two juveniles and represents a rare association of body fossils and trace fossils of a single dinosaur taxon. While these fossils and their paleobiological implications were unprecedented, collection nevertheless necessitated removal of the burrow structure from its geological context and its destruction during body fossil preparation. Here we present the first photogrammetric models of the type locality burrow in its original geological context and three dimensional morphology, constructed from photos taken at three stages in excavation. Because the terminal extent of the burrow was collected prior to the burrow’s complete exposure, the structure was never documented in its entirety. A composite model provides the only holistic documentation of the entire burrow morphology as originally preserved. These models supplement the original burrow description, serve as comparative tools for identifying and diagnosing future discoveries, and demonstrate the utility of pre-existing photographs for later photogrammetric reconstruction.
... More recently information on late Albian to Cenomanian assemblages from western North America has been forthcoming from sediments deposited in southeastern Idaho and southwestern Montana, the Wayan Formation and Vaughn Member of the Blackleaf Formation, respectively (Figures 1 and 2). The Wayan Formation and Vaughn Member have produced similar but less diverse and fragmentary vertebrate assemblages (Table 1; Krumenacker et al. 2016;Krumenacker 2017;Varricchio et al. 2007). Here, the Wayan Formation and Vaughn Member are correlated for the first time using published geological and paleontological data and are shown to represent the same depositional system that has subsequently been disrupted by emplacement of the volcanic rocks of the Snake River Plain. ...
... Weishampel et al. (2002) described indeterminate theropod, ankylosaur, and ornithopod remains; as well as possible neoceratopsian remains. The most recent discoveries include ten partial skeletons, as well as numerous isolated remains of the burrowing neornithischian Oryctodromeus cubicularis, eggs and eggshell from the ootaxon Macroelongatoolithus carleylei, as well as fragmentary teeth and bones from numerous other vertebrate forms ( Fig. 3; Table 1; Krumenacker 2010;Simon 2014;Krumenacker et al. 2016;Krumenacker 2017). ...
... Vertebrate remains reported from the Vaughn Member (Figure 3(b); Table 1) are less diverse, with the assemblage being dominated by partial to near complete skeletons of Oryctodromeus (eleven associated to partial specimens), sometimes associated with burrows (Varricchio et al. 2007;Krumenacker 2017). Other reported macrofossils include plants such as Tempskya, eggshell of the oospecies Macroelongatoolithus, and indeterminate reptilian bone fragments (Cobban et al. 1976; Dyman and Nichols 1988;Simon 2014). ...
The Mussentuchit Member of the Cedar Mountain Formation of eastern Utah represents the best source of data on Cenomanian vertebrate assemblages from North America. However, increasing data has recently been forthcoming from the late Albian to Cenomanian Wayan Formation of Idaho and Vaughn Member of the Blackleaf Formation of Montana, which are both at least partially coeval with the Mussentuchit Member. While the paleontological assemblages of the Wayan Formation and Vaughn Member are fragmentary, numerous vertebrate forms are represented, with the small burrowing neornithischian Oryctodromeus cubicularis dominating these assemblages. The differences between the Wayan Formation and Vaughn Member assemblages, the Mussentuchit and few other mid-Cretaceous assemblages are likely a result of some combination of preservational biases, paleogeography, and paleoenvironmental differences. The chronostratigraphy, fossil content, bracketing facies, and ages of the Wayan Formation and Vaughn Member suggest these sediments represent the same depositional system prior to disruption by subsequent tectonic and volcanic events. This assemblage from the Wayan Formation and Vaughn Member is here termed the Wayan-Vaughn Assemblage (WVA). Continued work in the WVA, particularly with microvertebrate materials, may reveal additional shared taxa between the WVA and other coeval units.
... Longitudinal protuberances developed on the spinal processes of the anterior caudal vertebrae (Figs. 9 and 10) could be the fused remnants of ossified tendons, as in V. canaliculatus . However, apart from these protuberances, ossified tendons are lacking in the tail of Diluvicursor, as in ornithopods such as Haya (Makovicky et al., 2011), Jeholosaurus , NMV P185992/P185993 (Herne, 2009), Orodromeus makelai and Parksosaurus (see Brown et al., 2013), which differ from many other ornithopods, such as Hypsilophodon (Galton, 1974), Oryctodromeus cubicularis (Brown et al., 2013;Krumenacker, 2017) and Tenontosaurus tilletti (Forster, 1990), where ossified tendons ensheath the caudal vertebrae. ...
A new small-bodied ornithopod dinosaur, Diluvicursor pickeringi , gen. et sp. nov., is named from the lower Albian of the Eumeralla Formation in southeastern Australia and helps shed new light on the anatomy and diversity of Gondwanan ornithopods. Comprising an almost complete tail and partial lower right hindlimb, the holotype (NMV P221080) was deposited as a carcass or body-part in a log-filled scour near the base of a deep, high-energy river that incised a faunally rich, substantially forested riverine floodplain within the Australian–Antarctic rift graben. The deposit is termed the ‘Eric the Red West Sandstone.’ The holotype, interpreted as an older juvenile ∼1.2 m in total length, appears to have endured antemortem trauma to the pes. A referred, isolated posterior caudal vertebra (NMV P229456) from the holotype locality, suggests D. pickeringi grew to at least 2.3 m in length. D. pickeringi is characterised by 10 potential autapomorphies, among which dorsoventrally low neural arches and transversely broad caudal ribs on the anterior-most caudal vertebrae are a visually defining combination of features. These features suggest D. pickeringi had robust anterior caudal musculature and strong locomotor abilities. Another isolated anterior caudal vertebra (NMV P228342) from the same deposit, suggests that the fossil assemblage hosts at least two ornithopod taxa. D. pickeringi and two stratigraphically younger, indeterminate Eumeralla Formation ornithopods from Dinosaur Cove, NMV P185992/P185993 and NMV P186047, are closely related. However, the tail of D. pickeringi is far shorter than that of NMV P185992/P185993 and its pes more robust than that of NMV P186047. Preliminary cladistic analysis, utilising three existing datasets, failed to resolve D. pickeringi beyond a large polytomy of Ornithopoda. However, qualitative assessment of shared anatomical features suggest that the Eumeralla Formation ornithopods, South American Anabisetia saldiviai and Gasparinisaura cincosaltensis , Afro-Laurasian dryosaurids and possibly Antarctic Morrosaurus antarcticus share a close phylogenetic progenitor. Future phylogenetic analysis with improved data on Australian ornithopods will help to test these suggested affinities.
