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A new family of horned dinosaurs from the Cretaceous
... Though the name has been advocated to be the proper name for the clade (it has been (informally) defined by Sereno, 1998 andSereno, 2005), it was actually introduced 4 years later than Chasmosaurinae. Note that the Principle of Coordination, which would make Ceratopsinae attributable to Marsh (1888), rather than to Abel (1919), does not apply under the ICPN (see Note 9.15A.3). Therefore, Ceratopsinae would not have priority over Chasmosaurinae under the ICPN. ...
... Definition. The largest clade containing Pachycephalosaurus wyomingensis (Gilmore, 1931) but not Ceratops montanus Marsh, 1888 andTriceratops horridus Marsh, 1889. This is a maximum-clade definition. ...
... This is a maximum-clade definition. Abbreviated definition: max ∇ (Pachycephalosaurus wyomingensis (Gilmore, 1931)~Ceratops montanus Marsh, 1888& Triceratops horridus Marsh, 1889. ...
Ornithischians form a large clade of globally distributed Mesozoic dinosaurs, and represent one of their three major radiations. Throughout their evolutionary history, exceeding 134 million years, ornithischians evolved considerable morphological disparity, expressed especially through the cranial and osteodermal features of their most distinguishable representatives. The nearly two-century-long research history on ornithischians has resulted in the recognition of numerous diverse lineages, many of which have been named. Following the formative publications establishing the theoretical foundation of phylogenetic nomenclature throughout the 1980s and 1990s, many of the proposed names of ornithischian clades were provided with phylogenetic definitions. Some of these definitions have proven useful and have not been changed, beyond the way they were formulated, since their introduction. Some names, however, have multiple definitions, making their application ambiguous. Recent implementation of the International Code of Phylogenetic Nomenclature (ICPN, or PhyloCode) offers the opportunity to explore the utility of previously proposed definitions of established taxon names. Since the Articles of the ICPN are not to be applied retroactively, all phylogenetic definitions published prior to its implementation remain informal (and ineffective) in the light of the Code. Here, we revise the nomenclature of ornithischian dinosaur clades; we revisit 76 preexisting ornithischian clade names, review their recent and historical use, and formally establish their phylogenetic definitions. Additionally, we introduce five new clade names: two for robustly supported clades of later-diverging hadrosaurids and ceratopsians, one uniting heterodontosaurids and genasaurs, and two for clades of nodosaurids. Our study marks a key step towards a formal phylogenetic nomenclature of ornithischian dinosaurs.
... The [10]. Faunal data from: 1, Sahni [12]; 2, Rogers and Brady [13]; 3, Marsh [3]; 4, Cope [14]; 5, Cope [15]; 6, Penkalski and Dodson [16]; 7, Ryan et al. [8]; 8, this study; 9, Leidy [17]; 10, Cope [18]; 11, Fiorillo and Currie [19]; 12, Fiorillo [20]; 13, Dodson [4]; 14, Freedman et al. [21]; 15, Schott et al. [22]; 16, Ryan [5]; 17, Ryan et al. [7]; 18, Longrich [6]. All taxa from terrestrial McClelland Ferry or Coal Ridge members. ...
... The first recognized ceratopsid was 'Ceratops montanus' (USNM 2411) from the upper JRF, known only from a pair of postorbital horncores ( Fig 6G) and partial occiput [3]. The holotype locality was described as the "northwestern slope near the summit, about 300 yards from the point of the first hogback that projects into the valley of Cow Creek from the west, just below where the old Cow Island and Fort Benton freight road descends into the valley of Cow Creek, about 10 miles above the confluence of that stream with the Missouri River" [46]. ...
... This places the site~53 km away from that of CMN 57081, and both sites are among the few located along the Missouri River to yield ceratopsid material. Marsh [3] initially illustrated the horncores of 'Ceratops' as projecting anterodorsally, but Hatcher et al. [46] subsequently showed that they instead projected dorsolaterally. In fact, the horncores closely resemble those of CMN 57081, which are just 20 mm longer (Fig 6A-6F). ...
This study reports on a new ceratopsid, Spiclypeus shipporum gen et sp. nov., from the lower Coal Ridge Member of the Judith River Formation in Montana, USA, which dates to ~76 Ma (upper Campanian). The species is distinguished by rugose dorsal contacts on the premaxillae for the nasals, laterally projecting postorbital horncores, fully fused and anteriorly curled P1 and P2 epiparietals, and a posterodorsally projecting P3 epiparietal. The holotype specimen is also notable for its pathological left squamosal and humerus, which show varied signs of osteomyelitis and osteoarthritis. Although the postorbital horncores of Spiclypeus closely resemble those of the contemporaneous ‘Ceratops’, the horncores of both genera are nevertheless indistinguishable from those of some other horned dinosaurs, including Albertaceratops and Kosmoceratops; ‘Ceratops’ is therefore maintained as a nomen dubium. Cladistic analysis recovers Spiclypeus as the sister taxon to the clade Vagaceratops + Kosmoceratops, and appears transitional in the morphology of its epiparietals. The discovery of Spiclypeus adds to the poorly known dinosaur fauna of the Judith River Formation, and suggests faunal turnover within the formation.
... As forMadzia et al. (2021). The largest clade containing Pachycephalosaurus wyomingensis(Gilmore, 1931) but not Ceratops montanusMarsh, 1888 and Triceratops horridus Marsh, 1889. This is a maximum-clade definition. ...
... As forMadzia et al. (2021). The largest clade containing Ceratops montanusMarsh, 1888 and ...
... The horned dinosaurs (Ceratopsidae Marsh, 1888) were an abundant and species-rich clade of large, herbivorous quadrupeds from the Late Cretaceous of North America and Asia. They are distinguished by facial horns over the eyes and nose, and by the elaborate parietosquamosal frill that emerges from the back of the skull. ...
The horned dinosaur genus Torosaurus has a challenging history, relating both to its geographic distribution and taxonomy. Whereas Torosaurus has been reported from Upper Maastrichtian deposits in Canada, which would mark the northernmost range of the genus, recent work has questioned the generic identity of the implicated material, which primarily consists of a pair of cranial frills. Perhaps more problematically, the validity of the genus itself has been a subject of recent debate, with some arguing that Torosaurus is simply a skeletally mature growth form of the contemporaneous Triceratops. In this study, we describe and illustrate the relevant frill material from Canada, and determine that it is most plausibly attributable to the Torosaurus morph. Moreover, we apply for the first time osteohistological sampling to some postcranial material associated with one of the frills, and find that the animal was still growing at the time of death. This finding, in addition to other considerations presented here, leads us to conclude that Torosaurus is a valid genus, and is not simply a mature growth form of Triceratops.
... The horned dinosaurs (Ceratopsidae Marsh, 1888) were an abundant and species-rich clade of large, herbivorous quadrupeds from the Late Cretaceous of North America and Asia. They are distinguished by facial horns over the eyes and nose, and by the elaborate parietosquamosal frill that emerges from the back of the skull. ...
The horned dinosaur genus Torosaurus has a challenging history, relating both to its geographic distribution and taxonomy. Whereas Torosaurus has been reported from Upper Maastrichtian deposits in Canada, which would mark the northernmost range of the genus, recent work has questioned the generic identity of the implicated material, which primarily consists of a pair of cranial frills. Perhaps more problematically, the validity of the genus itself has been a subject of recent debate, with some arguing that Torosaurus is simply a skeletally mature growth form of the contemporaneous Triceratops. In this study, we describe and illustrate the relevant frill material from Canada, and determine that it is most plausibly attributable to the Torosaurus morph. Moreover, we apply for the first time osteohistological sampling to some postcranial material associated with one of the frills, and find that the animal was still growing at the time of death. This finding, in addition to other considerations presented here, leads us to conclude that Torosaurus is a valid genus, and is not simply a mature growth form of Triceratops.
... The only identified taxa reported to date from this unit are Gryposaurus incurvimanus (Horner, 1992) and Stegoceras validum (Sues and Galton, 1987;Goodwin, 1990). It is unclear from which horizon the holotype of Ceratops montanus (Marsh, 1888) may have been recovered. ...
... The clade Ceratopsia has been known since the late 19th century (Marsh, 1889), and the elaborate horns and frills of the ceratopsids (Hatcher et al., 1907;Lull, 1933; are well known to a wide audience (Dodson, 1996). Non-ceratopsoid neoceratopsians (hereafter referred to as basal neoceratopsians) (You and Dodson, 2004) form a relatively diverse group of smallbodied herbivorous dinosaurs that can be found from mid-Early to latest Late Cretaceous (Barremian-Maastrichtian). For many years, the diversity of all non-ceratopsid ceratopsians, including basal neoceratopsians, was restricted to Leptoceratops (Brown, 1914;Sternberg, 1951), Protoceratops andrewsi (Granger and Gregory, 1923;Gregory and Mook, 1925;Brown and Schlaikjer, 1940), and Montanoceratops (Brown and Schlaikjer, 1942;Sternberg, 1951). ...
Basal neoceratopsians are a relatively diverse group of small- to medium-sized herbivorous dinosaurs from the Early to Late Cretaceous of Asia and North America. Although known for over a century, this group has only relatively recently received intense independent study, tied to the rapid increase in known diversity since 1997. Auroraceratops rugosus is one of these recently discovered species and is one of the best-known basal neoceratopsians, being represented by over 80 specimens, and is also the most completely represented neoceratopsian from the Early Cretaceous. A phylogenetic analysis focusing on non-ceratopsid ceratopsians examines the phylogenetic context of Auroraceratops. The analysis is based on a new matrix of 41 taxa and 257 characters. The results recover an Auroraceratops-Aquilops-ZPAL MgD-I/156 clade within basal Neoceratopsia that is sister to a clade composed of Asiaceratops, Yamaceratops, Mosaiceratops, and the larger clades Leptoceratopsidae and Coronosauria. This phylogeny recovers a monophyletic Coronosauria, Leptoceratopsidae, and Protoceratopsidae. Helioceratops is recovered as sister to the rest of Leptoceratopsidae, Ischioceratops is recovered nested within Leptoceratopsidae, and the enigmatic genus Mosaiceratops is recovered as a basal neoceratopsian, sister to Yamaceratops. Yinlong, and Hualianceratops are recovered in an expanded Chaoyangsauridae, and the genus Psittacosaurus is recovered as the earliest diverging lineage in Ceratopsia. Ajkaceratops, the only European ceratopsian, is robustly recovered as sister to the rest of Ceratopsoidea.
SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP
Citation for this article: Morschhauser, E. M., H. You, D. Li, and P. Dodson. 2019. Phylogenetic history of Auroraceratops rugosus (Ceratopsia: Ornithischia) from the Lower Cretaceous of Gansu Province, China; pp. 117–147 in Hailu You, Peter Dodson, and Eric Morschhauser (eds.), Auroraceratops rugosus (Ornithischia, Ceratopsia) from the Early Cretaceous of northwestern Gansu Province, China. Society of Vertebrate Paleontology Memoir 18. Journal of Vertebrate Paleontology 38(Supplement). DOI: 10.1080/02724634.2017.1509866.
... Spiclypeus shipporum Mallon et al., 2016 also has a step at the base of the right postorbital horncore, but the step is restricted to the posterior side of the horncore, and it appears to be formed by extensive pitting rather than overgrowth. The holotype horncores of 'Ceratops montanus' (Marsh, 1888) from the Judith River Formation (Mallon et al., 2016) do not have this overgrowth. On the ventral side of the horncore, there is a round foramen that is suggestive of resorption (Fig. 6.5), which is known to occur in postorbital horncores of various eucentrosauran centrosaurines, such as Coronosaurus (Ryan and Russell, 2005), Spinops (Farke et al., 2011), Centrosaurus (Ryan et al., 2001;Tanke and Farke, 2006), Styracosaurus , and Einiosaurus (Sampson, 1995), but not in non-Eucentrosaura centrosaurines. ...
Medusaceratops lokii Ryan, Russell, and Hartman, 2010 is an enigmatic taxon of ceratopsid represented by partial parietals from the Mansfield bonebed in the Campanian Judith River Formation, Montana. Originally, all ceratopsid material collected from this bonebed was referred to the centrosaurine ceratopsid Albertaceratops , but subsequently two parietals were designated the types of the chasmosaurine, M . lokii , in part, because they were interpreted to have three epiparietals bilaterally. Here we describe new material from the bonebed that allows a systematic revision of the taxon. A revised reconstruction of the frill, informed by newly discovered parietals, reveals that M . lokii had a broad midline ramus and at least five epiparietals (ep) around the margin of the frill, both traits that are characteristic of Centrosaurinae. From medial to lateral, the epiparietal ornamentation consists of a small, variably procurving epiparietal (ep 1), an anterolaterally curving pachyostotic hook (ep 2), a smaller pachyostoic process (ep 3), and two small triangular epiparietals (ep 4 and 5). A phylogenetic analysis of ceratopsids, which is the first to include Medusaceratops , indicates that M . lokii is a unique, early centrosaurine ceratopsid taxon that is more closely related to Centrosaurini and Pachyrhinosaurini than Nasutoceratopsini. No unequivocal chasmosaurine bones or diagnostic material from any other ceratopsid could be identified from the Mansfield bonebed, suggesting that it represents one of the oldest occurrences of a monodominant accumulation of a centrosaurine ceratopsid on record.
... In this study, only definitive hesperornithiform remains were used for palaeobiogeographical analysis. Therefore, the well-recognized hesperornithiform remains known today are restricted to the Northern Hemisphere (Marsh 1893;Shufeldt 1915;Fox 1974;Martin & Bonner 1977;Bryant 1983;Nessov & Prizemlin 1991;Martin & Varner 1992;Tokaryk & Harington 1992;Tokaryk et al. 1997;Malakhov & Ustinov 1998;Hill et al. 1999;Hou 1999;Galton & Martin 2002a, b;Martin & Lim 2002;Panteleyve et al. 2004;Everhart 2011;Wilson et al. 2011;Martin et al. 2012;Bell et al. 2015;Aotsuka & Sato 2016;summarized in Figs 15, 16). ...
Asian hesperornithiforms are extremely rare in contrast to the much more abundant record from North America. In Asia, these fossil birds are only known from fragmentary materials from Mongolia. Here we describe the skeletal remains of a new hesperornithiform Chupkaornis keraorum gen. et sp. nov. from the Upper Cretaceous Kashima Formation (Coniacian to Santonian) of the Yezo Group in Mikasa City, Hokkaido, Japan. This is the best-preserved hesperornithiform material from Asia and it is the first report of hesperornithiforms from the eastern margin of the Eurasian continent. Chupkaornis has a unique combination of characters: finger-like projected tibiofibular crest of femur, deep, emarginated lateral excavation with a sharply defined edge of the ventral margin of the thoracic vertebrae, and the heterocoelous articular surface of the thoracic vertebrae. Our new phylogenetic analysis revises the phylogenetic relationships of Hesperornithiformes. In contrast to previous studies, Enaliornis is assigned as the most basal taxon and Baptornis is positioned as more derived than Brodavis. Chupkaornis is a sister taxon to the clade of Brodavis and higher taxa. Parahesperornis and Hesperornis are positioned within Hesperornithidae, the derived Hesperornithiformes. Many of the skeletal character changes are concentrated at the base of Hesperornithidae (Parahesperornis and more derived taxa), and involve the modification of the pelvic girdle and hind limb morphology (e.g. dorsal directed antitrochanter of pelvis, short and sprawled femur, including probable lobe-toed feet suggested by the specialized distal articular surface of first digit of fourth toe, and predominantly robust digit IV phalanges). These skeletal modifications are likely adaptations for foot-propelled diving behaviour. http://zoobank.org/urn:lsid:zoobank.org:pub:FB783237-E565-4B74-9386-EADF8E12DFD4 © The Trustees of the Natural History Museum, London 2017. All rights reserved.
... All materials were collected with permission from the Instituto Nacional Antropología e Historia National through its National Council of Paleontology under permit number 401.13-352. Systematic Paleontology: DINOSAURIA [38] ORNITHISCHIA [39] CERATOPSIA [40] NEOCERATOPSIA [41] CERATOPSIDAE [42] CENTROSAURINAE [43] Material--CPC 274 is an indeterminant centrosaurine ceratopsid composed of a partial skull and partial postcranium consisting of a nearly complete right squamosal, fragmentary parietal, dentary, premaxillary fragment, complete scapula and femur, left preacetabular process of the ilium, and partial dorsal vertebra. It is not yet clear where in the Aguja Formation the locality occurs due to the low relief leading to a lack of nearby rocks that can be correlated with the field site. ...
While centrosaurines and ceratopsids in general are abundant in the Late Campanian of northern Laramidia, they are much less commonly found in southern Laramidia. This has supported hypotheses of dinosaur provinciality and endemism in the Late Cretaceous with the delineation of at least two separate faunal zones, north and south Laramidia. There have been 12 genera of centrosaurines recognized from northern Laramidia while two genera, Diabloceratops and Nasutoceratops, have been named from southern Laramidia. We present an osteological description and taphonomic outline for a new centrosaurine ceratopsid from the Aguja Formation of northern Coahuila, Mexico that is not currently diagnosable to the generic level, but likely represents a new taxon. Further, we have included three-dimensional surface scans of all material attributed to this animal. Considering the large number of centrosaurines from northern Laramidia, it is likely that cladistic analyses are biased towards this faunal zone. New findings of southern centrosaurines are needed to correct this bias. This discovery expands the range of centrosaurines south to Coahuila, Mexico and adds new information to better characterize the morphology and taxonomy of centrosaurines from southern Laramidia and their evolution in comparison to their northern counterparts.
... Other previously named chasmosaurine taxa from the DPF are either a junior synonym of one of the above valid taxa (i.e., Mojoceratops perifania a junior synonym of C. russelli), insufficiently preserved to confirm its validity (Chasmosaurus canadensis), a junior synonym of the latter (Chasmosaurus kaiseni), non-diagnostic (Chasmosaurus brevirostris), or not present in the DPF (Kosmoceratops). SYSTEMATIC PALAEONTOLOGY CERATOPSIA [64] NEOCERATOPSIA [65] CERATOPSIDAE [66] CHASMOSAURINAE [67] CHASMOSAURUS [2] Emended diagnosis (modified from Konishi [9])-Chasmosaurus is diagnosed based on the following unique combination of characters: (1) Premaxillary flange along entire anterior margin of external naris; (2) postorbital horncores, when present, curve posteriorly along their length; (3) squamosal dorsal border laterally adjacent to dorsal temporal fenestra straight in profile, anteriorly at level with base of postorbital horncore, and sloping posteroventrally at a shallow angle before ascending farther posteriorly to form lateral border of parietal fenestra; (4) medial margin of squamosal, where it articulates with the lateral bar of the parietal, straight; (5) frill broadens posteriorly to form rectangular to triangular shield with maximum width more than twice the skull width at orbits; (6) parietal fenestrae large, occupying most of the parietal, and being rounded or anteroposteriorly longer than transversely wide; and (7) epiparietals straight and triangular in shape and oriented posteriorly or anterodorsally. ...
Background:
The chasmosaurine ceratopsid Chasmosaurus is known from the Upper Cretaceous (Campanian) Dinosaur Park Formation of southern Alberta and Saskatchewan. Two valid species, Chasmosaurus belli and C. russelli, have been diagnosed by differences in cranial ornamentation. Their validity has been supported, in part, by the reported stratigraphic segregation of chasmosaurines in the Dinosaur Park Formation, with C. belli and C. russelli occurring in discrete, successive zones within the formation.
Results/conclusions:
An analysis of every potentially taxonomically informative chasmosaurine specimen from the Dinosaur Park Formation indicates that C. belli and C. russelli have indistinguishable ontogenetic histories and overlapping stratigraphic intervals. Neither taxon exhibits autapomorphies, nor a unique set of apomorphies, but they can be separated and diagnosed by a single phylogenetically informative character-the embayment angle formed by the posterior parietal bars relative to the parietal midline. Although relatively deeply embayed specimens (C. russelli) generally have relatively longer postorbital horncores than specimens with more shallow embayments (C. belli), neither this horncore character nor epiparietal morphology can be used to consistently distinguish every specimen of C. belli from C. russelli.
Status of kosmoceratops in the dinosaur park formation:
Kosmoceratops is purportedly represented in the Dinosaur Park Formation by a specimen previously referred to Chasmosaurus. The reassignment of this specimen to Kosmoceratops is unsupported here, as it is based on features that are either influenced by taphonomy or within the realm of individual variation for Chasmosaurus. Therefore, we conclude that Kosmoceratops is not present in the Dinosaur Park Formation, but is instead restricted to southern Laramidia, as originally posited.
The Ojinaga Basin is crucial for understanding the southern province of Laramidia because it contains a unique dinosaur fauna on the North American continent. The Upper Cretaceous Aguja and Javelina formations contain fossil remains of the dinosaur families Hadrosauridae, Ceratopsidae, Nodosauridae, Tyrannosauridae, and Saltasauridae. The latter is the first evidence for a saltasaurid taxon from Mexico identified as Alamosaurus sanjuanensis.
The Late Cretaceous of western North America supported diverse dinosaur assemblages, though understanding patterns of dinosaur diversity, evolution, and extinction has been historically limited by unequal geographic and temporal sampling. In particular, the existence and extent of faunal endemism along the eastern coastal plain of Laramidia continues to generate debate, and finer scale regional patterns remain elusive. Here, we report a new centrosaurine ceratopsid, Lokiceratops rangiformis , from the lower portion of the McClelland Ferry Member of the Judith River Formation in the Kennedy Coulee region along the Canada-USA border. Dinosaurs from the same small geographic region, and from nearby, stratigraphically equivalent horizons of the lower Oldman Formation in Canada, reveal unprecedented ceratopsid richness, with four sympatric centrosaurine taxa and one chasmosaurine taxon. Phylogenetic results show that Lokiceratops , together with Albertaceratops and Medusaceratops , was part of a clade restricted to a small portion of northern Laramidia approximately 78 million years ago. This group, Albertaceratopsini, was one of multiple centrosaurine clades to undergo geographically restricted radiations, with Nasutuceratopsini restricted to the south and Centrosaurini and Pachyrostra restricted to the north. High regional endemism in centrosaurs is associated with, and may have been driven by, high speciation rates and diversity, with competition between dinosaurs limiting their geographic range. High speciation rates may in turn have been driven in part by sexual selection or latitudinally uneven climatic and floral gradients. The high endemism seen in centrosaurines and other dinosaurs implies that dinosaur diversity is underestimated and contrasts with the large geographic ranges seen in most extant mammalian megafauna.
A nearly complete skull of a new ceratopsid dinosaur, Bisticeratops froeseorum, is described from the Farmington Member of the Kirtland Formation (late Campanian, Upper Cretaceous) of New Mexico. Bisticeratops is distinguished by several diagnostic cranial characters, including those of the premaxilla (stepped dorsal margin), maxilla (short jugal process lacking the ventral pocket-like fossa), jugal (short maxillary process of the jugal), and palpebral ornamentation (short with moderate ornamentation). It differs from other known chasmosaurines, especially from stratigraphically older species in the same geographic region, Pentaceratops sternbergi and Titanoceratops ouranos, by a strongly reduced jugal process of the maxilla and an unusual maxilla/jugal contact, which forms a shallow, triangular-shaped lateroposteriorly concave sulcus. A phylogenetic analysis recovers Bisticeratops froeseorum as sister species to the unnamed Almond Formation chasmosaurine and as a member of a potentially new southern clade of chasmosaurines, outside the Triceratopsini, and distinct from other southern Laramidian chasmosaurines such as Pentaceratops. The dinosaur fauna of the Farmington Member is comparatively poorly understood, especially compared to stratigraphically older faunas in the San Juan Basin. Therefore, the new, presumably rare species Bisticeratops froeseorum, together with several recently named and described chasmosaurines such as Navajoceratops sullivani, Sierraceratops turneri, and Terminocavus sealeyi, add to the diversity and disparity of chasmosaurines and provides further support for latitudinal variation in the ceratopsid fauna during the Late Cretaceous interval in the Western Interior Basin of North America.
One of the southernmost North American late Campanian microvertebrate assemblages was collected from the upper Aguja Formation, Big Bend National Park, Texas. The dinosaurs provide additional evidence that distinct southern and northern terrestrial vertebrate provinces occurred contemporaneously during this time due to latitudinal differences in temperature and rainfall. Southern areas, such as west Texas, were warm dry, with non-seasonal climates, and with open-canopy woodlands; they appear to be less fossil-rich and less diverse than northern areas. Nine dinosaurs are present, based on isolated teeth: pachycephalosaurid; hadrosaurid; ceratopsian; tyrannosaurid; Saurornitholestes cf. langstoni (Sues, 1978); Richardoestesia cf. gilmorei (Currie et al., 1990); a new species of Richardoestesia, which is named here; and a undetermined theropod unlike any previously described. Previous reports of Troodon sp. from the Talley Mt. and Terlingua microsites are mistaken; they are a pachycephalosaurid. Many of the dinosaur teeth are small, and are probably from juveniles or younger individuals, evidence that dinosaurs nested in the area. Paleoecologically, the upper Aguja was probably more similar to the lower and more inland faunas of the Scollard Formation (~66 Ma) of Alberta than to contemporaneous northern faunas: both had drier, open environments and lower dinosaur abundance. This connection between climate and dinosaur abundance suggests that climatic factors were important in the Late Cretaceous dinosaur extinctions.
The horned dinosaurs (Ceratopsidae) were a diverse family of herbivorous dinosaurs originating in the Late Cretaceous in western North America (Laramidia). As one of the most species-rich dinosaur groups, their diversity and distribution are important to understanding Cretaceous dinosaur evolution. Ceratopsids have previously been hypothesized to have high levels of endemism despite inhabiting a relatively small land mass with few barriers to dispersal. Here, we document a new chasmosaurine ceratopsid, Sierraceratops turneri gen. et sp. nov., from the Upper Cretaceous (latest Campanian–Maastrichtian) Hall Lake Formation of south-central New Mexico, consistent with the hypothesis that southern Laramidia supported an endemic dinosaur fauna. Sierraceratops is distinguished by its relatively short, robust, and mediolaterally compressed postorbital horns; a flattened medial ridge on the posterior end of the pterygoid; a jugal with pronounced anterior flanges; a long pyramid-shaped epijugal horncore; a D-shaped cross section of the median parietal bar; and a squamosal with a pointed tip and low episquamosal ossifications. Phylogenetic analysis recovers Sierraceratops as sister to Bravoceratops and Coahuilaceratops, part of a clade endemic to the southwestern United States and Mexico. Sierraceratops adds to the diversity and disparity of the Chasmosaurinae in the Late Cretaceous and provides additional evidence for Laramidian endemism. Together with Sierraceratops, the Hall Lake Formation dinosaur fauna suggests that the latest Cretaceous of southern Laramidia was characterized by endemic clades and distinct community structures.
This book Mexican Biodiversity and Ecology: New knowledge and technologies for current challenges is a compilation of scientific studies carried out by researchers from various institutions in the country. Its objective is to present current information on issues of biological diversity and ecology of relevant species in terms of conservation, as well as aspects of sustainable use of natural resources. Bio-logical diversity comprises the accumulation of living organisms considering all levels of their organization (genes, populations, species, communities, habitats, ecosystems and landscapes). Ecology, on the other hand, seeks to understand the relationships that exist between organisms and the biotic and abiotic elements in their environment. Both lines of research are closely related and form the basis for the appropriate use of available natural resources. In this context, the studies presented in this book deal with the diversity of bacterial genes, microbiotas, yeasts, snails, shrimps, insects, fish, dinosaurs, avifauna and vegetation. In the ecological aspect, varied information is offered covering climatic issues, fires, the effect of growth-promoting bacteria in plants, as well as relevant topics on fish, herpetofauna, birds, mammals, fungi, lichens and vegetation. Regarding the use of natural resources, the book contains information on the use of species for economic and human health purposes, biological control, biostimulants, bacterial biocontrol activity, meliponiculture and environmental education through botanical gardens.
It is hoped that this work will provide the reader with a broad overview of the topics that are currently being studied in these lines of research and that seek to increase knowledge of living beings, promoting their conservation and sustainable use.
conservation and sustainable use.
An associated incomplete skeleton of a ceratopsid dinosaur from the Campanian deposits of the Allison Member of the Menefee Formation in New Mexico, USA is described. Although it was originally described over two decades ago, newly prepared portions of the Menefee Formation skeleton and reinterpretations of previously known morphology, in addition to newly described specimens have provided new information on ceratopsids, and centrosaurines in particular. These new data allow for a thorough reassessment of the specimen and the erection of a new taxon: Menefeeceratops sealeyi gen. et sp. nov., potentially the oldest recognized member of Centrosaurinae. Menefeeceratops sealeyi is represented by diagnostic cranial and postcranial skeletal elements. The cranial elements include a portion of the left premaxilla, a nearly complete left postorbital horncore, a parietal fragment, the right and left squamosals, the left jugal, the predentary, and the left dentary. Postcranial material consists of two cervical vertebrae, eight dorsal vertebrae, a partial sacrum with six sacral vertebrae, 11 dorsal ribs, the distal left radius, proximal and distal portions of the left ulna, the left femur, and a left metatarsal II. The taxonomic validity of Menefeeceratops sealeyi is supported by a combination of several morphological characters. These include a lack of epiossifications on the lateroposterior edge of the parietal (shared with Machairoceratops), three epiossifications on the squamosal, and three smaller, secondary undulations as part of episquamosal locus S1. There are also two subequal embayments on the posterior free margin of the squamosal with the more dorsal embayment (between episquamosal loci 1 and 2) distinctly larger than the ventral (= lateroventral) one (between episquamosal loci 2 and 3), three ridges on the lateral (dorsolateral) surface of the squamosal, an elongate posterior portion of the squamosal, the presence of a shallow but distinct groove on the medial surface of the squamosal nearly paralleling the ventrolateral and ventroposterior edges, elongate postorbital (= supraorbital) horns that are anteriorly curved distally, and two elongate ridges on the lateral surface of the dentary that diverge anteriorly, creating a distinct anterior triangular fossa. Phylogenetic analysis of Menefeeceratops sealeyi places this new species as a basal centrosaurine, most closely related to Crittendenceratops krzyzanowskii, thus adding to the growing record of centrosaurines discovered in western North America. It thus provides new information about the diversity of morphologies throughout different species and the temporal and paleobiogeographic distribution of these animals throughout Laramidia during the Late Cretaceous. Its presence as one of the, if not the, oldest members of the Centrosaurinae also suggests centrosaurines originated in the southern portions of western North America and the southern Rocky Mountain region, and subsequently radiated north during the upper middle to late Campanian.
El cambio climático puede influenciar la frecuencia, severidad y extensión de los incendios forestales. Los incendios son perturbaciones comunes en el medio ambiente que pueden tener repercusiones ecológicas y económicas graves e impredecibles; no obstante, también es un conductor importante del funcionamiento del ecosistema, la dinámica de la biota y el ciclo de nutrientes. Es por lo anterior, que el presente trabajo tuvo como objetivo identificar el impacto en la actividad microbiana total del suelo después de un incendio ocurrido en el Cañón de San Lorenzo. Los resultados demostraron un incremento en el pH, CE y MOS en comparación a la zona testigo no incendiada, mas no fue significativo estadísticamente. Por otro lado, la respiración basal sí presentó diferencia significativa entre la zona incendiada y testigo durante todo el tiempo de incubación, presentando una disminución en la zona perturbada, lo que pudo deberse a factores como la transferencia del calor del fuego en el subsuelo que incrementa directamente la mortalidad de las comunidades microbianas, disminuyendo así la biomasa y metabolismo, así como a una menor humedad en el suelo, el cambio de las
propiedades fisicoquímicas o la baja disponibilidad de nutrientes fácilmente degradables.
Se describe la abundancia y diversidad de bacterias fecales de un pool de muestras de caballo en libre pastoreo en la reserva de la Biosfera Mapimí. Se realizó secuenciación masiva V3-V4 del gen 16S rRNA con Illumina.
Los resultados se analizaron con QIIME y la referencia taxonómica EzBioCloud. Se identificaron 10 phyla, 16 clases, 26 órdenes, 46 familias, 134 géneros y 136 especies. Los phyla Proteobacteria, Firmicutes y Actinobacteria fueron los más abundantes. El género de mayor abundancia fue Brevudimonas; se identificaron cinco géneros asociados a infecciones en caballos (Clostridium, Fusobacterium, Klebsiella, Nocardia y Rhodococcus).
Ceratopsids (“horned dinosaurs”) are known from numerous specimens in western North America and Asia, a distribution reflecting the inferred subaerial link between the two landmasses during the Late Cretaceous. However, this clade was previously unknown from eastern North America, presumably due to limited outcrop of the appropriate age and depositional environment as well as the separation of eastern and western North America by the Western Interior Seaway during much of the Late Cretaceous. A dentary tooth from the Owl Creek Formation (late Maastrichtian) of Union County, Mississippi, represents the first reported occurrence of Ceratopsidae from eastern North America. This tooth shows a combination of features typical of Ceratopsidae, including a double root and a prominent, blade-like carina. Based on the age of the fossil, we hypothesize that it is consistent with a dispersal of ceratopsids into eastern North America during the very latest Cretaceous, after the two halves of North America were reunited following the retreat of the Western Interior Seaway.
Ceratopsids (“horned dinosaurs”) are known from western North America and Asia, a distribution reflecting an inferred subaerial link between the two landmasses during the Late Cretaceous. However, this clade was previously unknown from eastern North America, presumably due to limited outcrop of the appropriate age and depositional environment as well as the separation of eastern and western North America by the Western Interior Seaway during much of the Late Cretaceous. A dentary tooth from the Owl Creek Formation (late Maastrichtian) of Union County, Mississippi, represents the first reported occurrence of Ceratopsidae from eastern North America. This tooth shows a combination of features typical of Ceratopsidae, including a double root and a prominent, blade-like carina. Based on the age of the fossil, we hypothesize that it is consistent with a dispersal of ceratopsids into eastern North America during the very latest Cretaceous, presumably after the two halves of North America were reunited following the retreat of the Western Interior Seaway.
Ceratopsids (“horned dinosaurs”) are known from western North America and Asia, a distribution reflecting an inferred subaerial link between the two landmasses during the Late Cretaceous. However, this clade was previously unknown from eastern North America, presumably due to limited outcrop of the appropriate age and depositional environment as well as the separation of eastern and western North America by the Western Interior Seaway during much of the Late Cretaceous. A dentary tooth from the Owl Creek Formation (late Maastrichtian) of Union County, Mississippi, represents the first reported occurrence of Ceratopsidae from eastern North America. This tooth shows a combination of features typical of Ceratopsidae, including a double root and a prominent, blade-like carina. Based on the age of the fossil, we hypothesize that it is consistent with a dispersal of ceratopsids into eastern North America during the very latest Cretaceous, presumably after the two halves of North America were reunited following the retreat of the Western Interior Seaway.
Three new chasmosaurines from the Kirtland Formation (~75.0–73.4 Ma), New Mexico, form morphological and stratigraphic intermediates between Pentaceratops (~74.7–75 Ma, Fruitland Formation, New Mexico) and Anchiceratops (~72–71 Ma, Horseshoe Canyon Formation, Alberta). The new specimens exhibit gradual enclosure of the parietal embayment that characterizes Pentaceratops , providing support for the phylogenetic hypothesis that Pentaceratops and Anchiceratops are closely related. This stepwise change of morphologic characters observed in chasmosaurine taxa that do not overlap stratigraphically is supportive of evolution by anagenesis. Recently published hypotheses that place Pentaceratops and Anchiceratops into separate clades are not supported. This phylogenetic relationship demonstrates unrestricted movement of large-bodied taxa between hitherto purported northern and southern provinces in the late Campanian, weakening support for the hypothesis of extreme faunal provincialism in the Late Cretaceous Western Interior.
Three new chasmosaurines from the Kirtland Formation (~75.0 - 73.4 Ma), New Mexico, form morphological and stratigraphic intermediates between Pentaceratops (~74.7 - 75Ma, Fruitland Formation, New Mexico) and Anchiceratops (~72 - 71Ma, Horseshoe Canyon Formation, Alberta). The new specimens exhibit gradual enclosure of the parietal embayment that characterizes Pentaceratops, providing support for the phylogenetic hypothesis that Pentaceratops and Anchiceratops are closely related. This stepwise change of morphologic characters observed in chasmosaurine taxa that do not overlap stratigraphically is supportive of evolution by anagenesis. Recently published hypotheses that place Pentaceratops and Anchiceratops into separate clades are not supported. This phylogenetic relationship demonstrates unrestricted movement of large-bodied taxa between hitherto purported northern and southern provinces in the Late Campanian, weakening support for the hypothesis of extreme faunal provincialism in the Late Cretaceous Western Interior.
The Dinosaur Park Formation (DPF) has a diverse assemblage of chasmosaurines currently represented by Chasmosaurus belli, C. russelli, Vagaceratops irvinensis, and Mercuriceratops gemini, and may also include remains possibly referable to Spiclypeus shipporum. Two skulls, YPM 2016 and AMNH 5402, previously referred to C. belli, both have a straight posterior parietal bar with five epiparietals present (YPM 2016) or inferred (AMNH 5402) on each side – the combination of which is unique to V. irvinensis. Based on our new morphological observations and interpretations of these two skulls, we recover V. irvinensis as a species of Chasmosaurus (C. irvinensis), although the interrelationships between C. irvinensis, C. belli, and C. russelli remain unclear. We refrain from formerly assigning YPM 2016 and AMNH 5402 to C. irvinensis, however, as their parietal fenestrae are significantly larger and their epiparietals are significantly shorter than those of C. irvinensis; instead, we reassign these two skulls to Chasmosaurus sp. Given the low stratigraphic position of YPM 2016 (unknown in AMNH 5402) relative to C. irvinensis, we believe this specimen to represent a basal member of the lineage leading to C. irvinensis. If our assessment is correct, this would indicate that the C. irvinensis lineage has a large degree of stratigraphic overlap with that of C. belli and C. russelli. The close phylogenetic relationship and supposed stratigraphic separation for these three taxa reported in previous studies were used to suggest that they may represent an anagenetic lineage, whereby C. russelli evolved into C. belli, and C. belli evolved into, and was entirely replaced by, the latter. However, the lack of stratigraphic separation between these three taxa indicates that they instead arose via cladogenesis.
The Early Cretaceous basal neoceratopsian dinosaur Auroraceratops rugosus was described based on a single skull recovered from the Gonpoquan Basin in northwestern Gansu Province, China. The genus is now known from cranial and postcranial remains representing at least 80 individuals, many of which come from the neighboring Yujingzi Basin, with an age of Aptian to earliest Albian (126-115 Ma). Among the new material were four syncervicals, representing the phylogenetically and temporally earliest occurrence of a syncervical in Ceratopsia. The anatomy of the syncervical matches that described in leptoceratopsids and protoceratopsids, with the first segment formed from a small atlas centrum, a much larger atlantal intercentrum, and a splint-like, divided atlantal neural arch. The axis bears a large hatchet-shaped neural spine and facets for a double-headed cervical rib. The centra of the first three cervical vertebrae and the first two intercentra are fused, though the boundaries of the individual elements are discernable. The relatively early temporal and phylogenetic appearance of a syncervical supports recent work that shows that the syncervical of ceratopsians is unrelated to the larger head size and cranial ornamentation characteristic of later appearing ceratopsian clades.
Citation for this article: Li, D., E. M. Morschhauser, H. You, and P. Dodson. 2019. The anatomy of the syncervical of Auroraceratops (Ornithischia: Ceratopsia), the oldest known ceratopsian syncervical; pp. 69–74 in Hailu You, Peter Dodson, and Eric Morschhauser (eds.), Auroraceratops rugosus (Ornithischia, Ceratopsia) from the Early Cretaceous of northwestern Gansu Province, China. Society of Vertebrate Paleontology Memoir 18. Journal of Vertebrate Paleontology 38(Supplement). DOI: 10.1080/02724634.2018.1510411.
The pachyrostran centrosaurine dinosaur Pachyrhinosaurus perotorum is the geologically youngest (Maastrichtian, 70–68.5 Ma) centrosaurine, and latitudinally highest distributed ceratopsid yet known. Continued preparation of material collected from the type locality, the Kikak-Tegoseak Quarry, has produced more examples of cranial material from multiple individuals, including partial skulls and incomplete parietals. The original reconstruction of the type parietal was incorrect, and the element is similar to that of other Pachyrhinosaurus species in bearing medially directed epiparietal 2 processes along its posterior margin. Pachyrhinosaurus perotorum is diagnosed by an upturned tip of the rostrum; a dorsally shifted rostral bone lacking a sharply downturned, parrot-like beak; an enlarged median ridge at the posterior end of the nasal boss; and, tentatively, a posterior sulcus on epiparietal 2 and a canal passing dorsoventrally through the base of epiparietal 2. A cladistic phylogenetic analysis incorporating new data from this and other recent studies of centrosaurine relationships recovers a monophyletic Pachyrhinosaurus clade. Pachyrhinosaurus perotorum and P. canadensis are found to be sister taxa, united by the presence of an extra ossification on the lateral surface of the rostrum between the narial fossa and nasal boss, and by enlarged supraorbital bosses that contact or nearly contact the posterior end of the nasal boss. Parietal and squamosal frill ornamentations alone do not adequately address the variables in craniofacial morphology needed to distinguish between species of Pachyrhinosaurus. © 2019, © The Trustees of the Natural History Museum, London 2019. All rights reserved.
A new ceratopsid dinosaur, Crittendenceratops krzyzanowskii, is described from the Fort
Crittenden Formation (Upper Cretaceous) of southeastern Arizona, and is based on two individuals
consisting of partial cranial material recovered from the same stratigraphic unit. A phylogenetic
analysis of ceratopsids recovers Crittendenceratops as a member of Nasutoceratopsini, a subclade
of Centrosaurinae defined as the stem-based clade of centrosaurine ceratopsids more closely related
to Avaceratops lammersi and Nasutoceratops titusi than to Centrosaurus apertus. Reconstruction
of the parietosquamosal frill based on two specimens indicates that C. krzyzanowskii is a unique,
nasutoceratopsin taxon. The parietosquamosal frill of C. krzyzanowskii had a broad medial ramus and at
least five epiparietal loci situated around the margin of the frill, a typical characteristic of Centrosaurinae.
The epiparietals are pronounced triangles that are dorsally concave and ventrally convex. Additionally,
two large, triangular hook-like flanges, nearly the size of the epiparietal loci, are situated along the
dorsomedial margin of the parietal ramus. The left squamosal has a pronounced dorsal ridge with a single
dorsal squamosal process and large episquamosal undulations, a typical characteristic of Centrosaurinae.
The presence of C. krzyzanowskii in Arizona indicates that the nasutoceratopsins persisted into the late
Campanian. The temporal and paleobiogeographic distribution of Nasutoceratopsini further weakens
the hypothesis of distinct northern and southern Laramidian provinces.
INTRODUCTION
During the Campanian, the centrosaurine ceratopsids
exhibited great morphological and taxonomic diversity. Their
paleobiogeographic range extends through much of western
North America, from Alaska to Mexico (Loewen et al., 2010;
Fiorillo and Tykoski, 2012; Rivera-Sylva et al., 2016, 2017).
Outside of North America, centrosaurines have also been
described from China, with Sinoceratops zhuchengensis (Xu
et al., 2010), a lineage which originated in North America and
radiated into Asia (Ryan et al., 2017).
During the past two decades, several new ceratopsian
taxa have been identified in North America (e.g., Ryan, 2007;
Sampson et al., 2010, 2013; Longrich, 2011, 2013; Wick and
Lehman, 2013; Ryan et al., 2014, 2017; Evans and Ryan, 2015;
Brown and Henderson, 2015; Lehman et al., 2016; Mallon et
al., 2016; Rivera-Sylva et al., 2016, 2017). The recognition of
these new taxa adds to the growing record of taxonomic and
morphologic diversity of ceratopsids.
Between the mid 1990’s and 2000, a number of new
ceratopsian specimens were collected by teams at the Arizona-
Sonora Desert Museum (ASDM) and the New Mexico Museum
of Natural History and Science (NMMNH) from the upper
Campanian Fort Crittenden Formation of Adobe Canyon within
the Santa Rita Mountains of southeastern Arizona (Figs. 1-2).
These new specimens provide important new information about
the morphologic and taxonomic diversity of Ceratopsidae in
North America. The NMMNH specimens were briefly described
by Heckert et al. (2003), who identified them as belonging to
a centrosaurine ceratopsian. This was based on the overall
morphology of the left squamosal, which has the characteristic
“stepped” squamosal-parietal contact, a feature that is present
in all centrosaurines (Ryan, 2007). The ASDM specimens are
previously undescribed specimens that are new additions to this
study.
Here, we re-describe the Fort Crittenden Formation
ceratopsian and
The horned Ceratopsidae represent one of the last radiations of dinosaurs, and despite a decade of intense work greatly adding to our understanding of this diversification, their early evolution is still poorly known. Here, two postorbital horncores from the upper Foremost Formation (Campanian) of Alberta are described, and at ∼78.5 Ma represent some of the geologically oldest ceratopsid material. The larger of these specimens is incorporated into a fused supraorbital complex, and preserves a massive, straight, postorbital horncore that is vertical in lateral view, but canted dorsolaterally in rostral view. Medially, the supracranial sinus is composed of a small, restricted caudal chamber, and a large rostral chamber that forms the cornual diverticulum. This morphology is distinct from that of the long-horned Chasmosaurinae, and similar to, but still different from, those of younger Centrosaurinae taxa. The smaller specimen represents an ontogenetically younger individual, and although showing consistent morphology to the larger specimen, is less taxonomically useful. Although not certain, these postorbital horns may be referable to a long-horned basal (i.e., early-branching, non-pachyrhinosaurini, non-centrosaurini) centrosaurine, potentially the contemporaneous Xenoceratops , largely known from the parietosquamosal frill. These specimens indicate the morphology of the supracranial sinus in early, long-horned members of the Ceratopsidae, and add to our understanding of the evolution of the cranial display structures in this iconic dinosaur clade.
Ceratopsids (“horned dinosaurs”) are known from western North America and Asia, a distribution reflecting an inferred subaerial link between the two landmasses during the Late Cretaceous. However, this clade was previously unknown from eastern North America, presumably due to limited outcrop of the appropriate age and depositional environment as well as the separation of eastern and western North America by the Western Interior Seaway during much of the Late Cretaceous. A dentary tooth from the Owl Creek Formation (late Maastrichtian) of Union County, Mississippi, represents the first reported occurrence of Ceratopsidae from eastern North America. This tooth shows a combination of features typical of Ceratopsidae, including a double root and a prominent, blade-like carina. Based on the age of the fossil, we hypothesize that it is consistent with a dispersal of ceratopsids into eastern North America during the very latest Cretaceous, presumably after the two halves of North America were reunited following the retreat of the Western Interior Seaway.
During the past decade, three new endemic taxa of ceratopsian ornithischians have been described from Mexico. Apparently, this group experienced a regional diversification in this area. To date Mexican Ceratopsia are represented by three species, one of which is a centrosaurine and two are chasmosaurines. Here we provide a critical review on Mexican ceratopsians and formally name a new centrosaurine ceratopsid species from the Aguja Formation as Yehuecauhceratops mudei. We also discuss possible causes for the rapid endemic diversification of Mexican ceratopsians.
A partial skull (CMN 8804) of a ceratopsid from the upper unit of the Campanian Oldman Formation of Alberta is the first Canadian example of the newly established Nasutoceratopsini, a new subclade of Centrosaurinae defined as the stem-based clade of centrosaurine ceratopsids more closely related to Nasutoceratops titusi than to Centrosaurus apertus. The new clade is diagnosed, in part, by having a parietosquamosal frill lacking modified epimarginals; a small nasal horncore; large, rostrolaterally directed postorbital horncores; and a relatively short, deep face. Although the CMN 8804 taxon closely resembles Nasutoceratops, its phylogenetic position within Nasutoceratopsini is unresolved. The CMN 8804 taxon would have been contemporaneous with dinosaurs from the lower portion of the Dinosaur Park Formation 200 km to the northwest in Dinosaur Provincial Park. The presence of the CMN 8804 taxon in Alberta, and the approximately contemporaneous Nasutoceratops in Utah, indicates that the nasutoceratopsins pers...
Most horned dinosaur remains recovered from the Aguja Formation in West Texas are referable to the endemic chasmosaurine Agujaceratops mariscalensis. One specimen, however, differs sufficiently to justify its designation as the holotype of a new species, Agujaceratops mavericus sp. nov. This specimen and an isolated postorbital horncore from the same vicinity are stratigraphically the highest found in the Aguja Formation. A well-preserved juvenile specimen exhibits some unique features, and others compatible with A. mavericus, but due to its immature condition cannot be identified with certainty. A parietal referred to A. mariscalensis is the most complete thus far known, and shows that the frill of this taxon is more elaborately ornamented than previously believed, bearing a set of large horn-like spikes at the posterolateral corners. These two species share features of the premaxilla and squamosal, which warrant their inclusion in the same genus. However, characters thought to distinguish the two species vary in a manner similar to that found in other chasmosaurines, where debate persists as to their taxonomic significance. A consensus species concept has yet to be adopted for ceratopsid genera, of which most are monotypic. As a result, the two Agujaceratops species could be interpreted as arbitrary anagenetic stages in a single lineage, end-members in a spectrum of ontogenetic and sex-associated variation in that lineage, or two sympatric lineages that occupied separate niches in the same range.
http://zoobank.org/urn:lsid:zoobank.org:pub:1846D524-AC7F-4126-8787-33B26D80CF52
A new genus of long-horned chasmosaurine ceratopsid is described from the Dinosaur Park Formation (upper Campanian) of Western Canada. Mojoceratops perifania is represented by a skull and a parietal from the Dinosaur Park Formation of Alberta and an isolated parietal from the Dinosaur Park Formation of Saskatchewan. Several other specimens are provisionally referred to this taxon. While Mojoceratops shares many plesiomorphies with Chasmosaurus , the animal lacks the forward-curving parietal epoccipitals and reduced postorbital horns that diagnose the genus Chasmosaurus , and it differs from all other chasmosaurines in exhibiting a prominent sulcus on the anterior margin of the parietal, swellings on the anterodorsal surface of the parietal rami, and a small accessory process on the first parietal epoccipital. Other unusual features include anteriorly extended parietal fenestrae, a broad, heart-shaped frill, and transverse expansion of the postfrontal fontanelle. The type material of “ Eoceratops canadensis ” and “ Chasmosaurus kaiseni ” are nondiagnostic and these names are therefore considered nomina dubia, but their morphology is consistent with Mojoceratops and they probably belong to this genus. The frill of Mojoceratops shows marked variation. Some of this variation probably results from intraspecific variation or ontogenetic changes, but because the Dinosaur Park Formation encompasses more than a million years of time, evolution may explain some of these differences. Phylogenetic analysis shows that Mojoceratops forms a clade with Agujaceratops mariscalensis ; Chasmosaurus is the most basal member of Chasmosaurinae.
A bone bed in the middle part of the Javelina Formation (Maastrichtian) in Texas yielded parts of about 37 identifiable ceratopsid dinosaur bones, mostly appendicular and limb girdle elements belonging to one juvenile and two adult individuals of Torosaurus cf. utahensis. The bone bed is a lag assemblage comprising large immobile parts of the skeletons accumulated in an abandoned stream channel. In general form and proportions the postcranial bones are similar to those in Pentaceratops sternbergi and are not as robust as those in Torosaurus latus or Triceratops horridus. A few cranial elements are preserved, including parts of a parietal, squamosal, maxilla, and two dentaries. The form of the parietal fragment is comparable to that of a more nearly complete specimen of Torosaurus cf. utahensis collected nearby at about the same stratigraphic level. The bone bed material provides a basis for the first skeletal reconstruction of this enigmatic horned dinosaur. Most characters used in diagnoses of T. utahensis and T. latus are inadequate. Only the raised bar along the squamosal/parietal suture, present in T. latus; and the midline epiparietal, absent in T. latus , may discriminate the two species.
One of the southernmost North American late Campanian microvertebrate assemblages was collected from the upper Aguja Formation, Big Bend National Park, Texas. The dinosaurs provide additional evidence that distinct southern and northern terrestrial vertebrate provinces occurred contemporaneously during this time due to latitudinal differences in temperature and rainfall. Southern areas, such as west Texas, were warm dry, with non-seasonal climates, and with open-canopy woodlands; they appear to be less fossil-rich and less diverse than northern areas. Nine dinosaurs are present, based on isolated teeth: pachycephalosaurid; hadrosaurid; ceratopsian; tyrannosaurid; Saurornitholestes cf. langstoni (Sues, 1978); Richardoestesia cf. gilmorei (Currie et al., 1990); a new species of Richardoestesia , which is named here; and a undetermined theropod unlike any previously described. Previous reports of Troodon sp. from the Talley Mt. and Terlingua microsites are mistaken; they are a pachycephalosaurid. Many of the dinosaur teeth are small, and are probably from juveniles or younger individuals, evidence that dinosaurs nested in the area. Paleoecologically, the upper Aguja was probably more similar to the lower and more inland faunas of the Scollard Formation (~66 Ma) of Alberta than to contemporaneous northern faunas: both had drier, open environments and lower dinosaur abundance. This connection between climate and dinosaur abundance suggests that climatic factors were important in the Late Cretaceous dinosaur extinctions.
Fragments of a ceratopsian dinosaur from the Maastrichtian Hell Creek Formation, Garfield County, Montana, are unlike any known ceratopsian. Diagnostic features include a low, rounded nasal boss, an especially deep rostral-premaxillary pit, and paired choanae. The snout is elongate. The new taxon, Ugrosaurus olsoni , is referred to the Ceratopsidae.
The Upper Cretaceous (middle-late Campanian) Wahweap Formation of southern Utah contains the oldest diagnostic evidence of ceratopsids (to date, all centrosaurines) in North America, with a number of specimens recovered from throughout a unit that spans between 81 and 77 Ma. Only a single specimen has been formally named, Diabloceratops eatoni, from the lower middle member of the formation. Machairoceratops cronusi gen. et sp. nov., a new centrosaurine ceratopsid from the upper member of the Wahweap Formation, is here described based on cranial material representing a single individual recovered from a calcareous mudstone. The specimen consists of two curved and elongate orbital horncores, a left jugal, a nearly complete, slightly deformed braincase, the left squamosal, and a mostly complete parietal ornamented by posteriorly projected, anterodorsally curved, elongate spikes on either side of a midline embayment. The fan-shaped, stepped-squamosal is diagnostic of Centrosaurinae, however, this element differs from the rectangular squamosal in Diabloceratops. Machairoceratops also differs in the possession of two anterodorsally (rather than laterally) curved epiparietal ornamentations on either side of a midline embayment that are distinguished by a posteromedially-oriented sulcus along the entire length of the epiparietal. Additionally, the parietosquamosal frill is lacking any other epiossifications along its periphery. Machairoceratops shares a triangular (rather than round) frill and spike-like epiparietal loci (p1) ornamentation with the stratigraphically lower Diabloceratops. Both parsimony and Bayesian phylogenetic analyses place Machairoceratops as an early-branching centrosaurine. However, the parsimony-based analysis provides little resolution for the position of the new taxon, placing it in an unresolved polytomy with Diabloceratops. The resultant Bayesian topology yielded better resolution, aligning Machairoceratops as the definitive sister taxon to a clade formed by Diabloceratops and Albertaceratops. Considered together, both phylogenetic methods unequivocally place Machairoceratops as an early-branching centrosaurine, and given the biostratigraphic position of Machairoceratops, these details increase the known ceratopsid diversity from both the Wahweap Formation and the southern portion of Laramidia. Finally, the unique morphology of the parietal ornamentation highlights the evolutionary disparity of frill ornamentation near the base of Centrosaurinae.
A new non-hadrosaurid hadrosauroid dinosaur (Datonglong tianzhenensis gen. et sp. nov.) is reported. The new taxon is recovered from the Upper Cretaceous Huiquanpu Formation of Tianzhen County, Shanxi Province in northern China, and represented by an almost complete right dentary with dentition. Different from all other hadrosauroids, Datonglong possesses two functional teeth in each alveolus, and the pattern of ridge development on the lingual surface of its dentary crown shows a unique combination of character states (for example: distally offset primary ridge; well-developed secondary ridge; no additional ridge(s); slightly distally curved apical half of primary ridge). Comparative studies indicate advanced non-hadrosaurid hadrosauroids experienced a complex pattern in the evolution of their dentary, especially dentary dentition. Derived hadrosaurid features occurred frequently in these taxa, such as high height/width ratio of tooth crown in Bactrosaurus, one primary and one faint ridges in Gilmoreosaurus, median placed primary ridge in Zhanghenglong, rostrally inclined coronoid process in Nanningosaurus, and two functional teeth in each alveolus in Datonglong. This implies incredible diversities and attempts close to the origin of Hadrosauridae and difficulties to elucidate their phylogenetic relationships.
The skull and associated postcrania of Nasutoceratops titusi, a basal centrosaurine ceratopsid from the Upper Cretaceous (Campanian) Kaiparowits Formation of Grand Staircase–Escalante National Monument, southern Utah, are herein described. Autapomorphies of this taxon include: an ectonaris that comprises 75% of preorbital skull length; pneumatic nasals; a hyper-robust premaxilla–maxilla contact; a double-faceted, medial flange on the maxilla contributing to the hard palate; and unique supraorbital horncores that are anterolaterally directed, anteriorly curved, torsionally twisted, and relatively enormous. A Bayesian analysis, the first conducted for ceratopsians, is coupled with a parsimony phylogenetic analysis of Centrosaurinae, with both analyses recovering Nasutoceratops as the sister taxon to Avaceratops lammersi from the late Campanian of Montana. Nasutoceratops titusi provides insights into the origins of Centrosaurinae and suggests the existence of a previously unknown clade of short-snouted, long-horned centrosaurines that we here hypothesize to have originated in the southern Western Interior Basin of North America.
SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP
Citation for this article: Lund, E. K., S. D. Sampson, and M. A. Loewen. 2016. Nasutoceratops titusi (Ornithischia, Ceratopsidae), a basal centrosaurine ceratopsid from the Kaiparowits Formation, southern Utah. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2015.1071265.
An articulated, 1.5 m long skeleton of a juvenile Chasmosaurus, lacking only the front limbs, pectoral girdles, and terminal caudal vertebrae, was collected from the Dinosaur Park Formation in Dinosaur Provincial Park, Alberta. The short, tall skull has a narrow frill that lacks a posterior embayment. Many of the cranial bones are co-ossified in spite of the small size of the specimen. The nasals form an incipient horncore, and the short, knob-like postorbital horncore lacks sinuses. The palpebral is not fused to the rest of the skull. The frontal fontanelle is keyhole-shaped. The triangular squamosal extends to the back of the parietals. Epiossifications are lacking, although the squamosal margin is thick and scalloped. The parietal has a pronounced midline sagittal crest. Parietal fenestrae, if present, would have been narrow and elongate. There are only 18 maxillary tooth positions. The syncervical comprises three co-ossified, but distinct vertebrae. Anterior caudal vertebrae support unfused caudal ribs. Ossified tendons in the neck, trunk, and sacrum do not extend into the tail. Hind limb proportions are comparable to those of adult ceratopsids. The pedal unguals are distally acute. Skin impressions are similar to those of mature chasmosaurines. Phylogenetic analysis, if all characters are coded as they are seen, suggests that the specimen is a basal chasmosaurine. When size or age dependent characters are recoded as ‘?,’ the specimen groups with other Chasmosaurus. These characters should only be used in phylogenetic analyses when all specimens are mature.SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVPCitation for this article: Currie, P. J., R. B. Holmes, M. J. Ryan, and C. Coy. 2016. A juvenile chasmosaurine ceratopsid (Dinosauria, Ornithischia) from the Dinosaur Park Formation, Alberta, Canada. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2015.1048348.
Fragmentary remains of a long-frilled ceratopsian dinosaur from the El Picacho Formation (Maastrichtian) of West Texas pertain to an undescribed form. The remains are, however, insufficient to fully characterize this species. This ceratopsian has long thick squamosals with marginal undulations, nasals lacking a discrete horncore, a thin parietal, and large trihedral epijugals. The braincase has very thick lateral walls, and a well- developed postfrontal foramen. Four species of horned dinosaurs are known from Upper Cretaceous strata of the American Southwest: Pentaceratops sternbergii, Chasmosaurus mariscalensis, Torosaurus utahensis, and the El Picacho ceratopsian. All of these belong to the subfamily Chasmosaurinae.
An exceptionally large skeleton of
Pentaceratops sternbergi
(Ornithischia:Ceratopsia) provides for the first time an accurate impression of the body proportions in this horned dinosaur. This is the only known specimen with a skull associated with most of the postcranial skeleton. The restored skull is nearly three meters in length and is thus the largest of any ceratopsian and the largest skull thus far known in any terrestrial vertebrate. The elongate rostrum, elaborate premaxillary structure, and complex frontal and cornual sinuses demonstrate a high level of intraspecific variability in these features. Such features are therefore likely not useful in providing species-level discrimination in other chasmosaurines. The function of the intricate chasmosaurine premaxillary narial structures is probably associated with an advanced level of herbivory.
Several heretofore undescribed fragmentary specimens of the horned dinosaur Pentaceratops sternbergii (Ornithischia: Ceratopsia) reveal previously unknown features of the skull and extend the known range of morphological variation in this species. Pentaceratops sternbergii possesses a well-developed postfrontal fontanelle and a braincase structure similar to that of other chasmosaurines. The posterior parietal margin bears a pair of upturned epoccipitals on either side of the midline, similar to the short hook-like processes in Anchiceratops. -from Author
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