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New Perspectives on Horned Dinosaurs

The Royal Tyrrell Museum Ceratopsian Symposium

Michael J. Ryan

Publication Year: 2010

Easily distinguished by the horns and frills on their skulls, ceratopsians were one of the most successful of all dinosaurs. This volume presents a broad range of cutting-edge research on the functional biology, behavior, systematics, paleoecology, and paleogeography of the horned dinosaurs, and includes descriptions of newly identified species.

Published by: Indiana University Press

Series: Life of the Past


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pp. ix-xi

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pp. xiii-xiv

Horned dinosaurs (ceratopsians) are among the best-loved and better-known groups within the Dinosauria. We are still learning more about them every day, which is why the Ceratopsian Symposium was convened at the Royal Tyrrell Museum of Palaeontology (Drumheller, Alberta) on September 22–24, 2007. The symposium was a joint venture among three ...

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pp. xv-17

We thank all of the participants who attended the Ceratopsian Symposium in 2007 and helped us realize that this volume would be a successful venture. We thank the authors for their attention to detail and timely responses to our numerous harangues about deadlines. We also thank the reviewers who did their jobs, ensuring that these contributions were of high ...

List of Contributors

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pp. xvii-xix

List of Reviewers

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pp. xxi-xxii


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pp. 26-27

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1. Forty Years of Ceratophilia

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pp. 3-17

With the death of my beloved and highly esteemed mentor John Ostrom (1928–2005), I seem to have become the dean, or at least the senior citizen, of ceratopsian studies. Of course my interest in dinosaurs came from my childhood in the 1950s, at a time when there was not nearly so much dinosaur ‘‘stuff.’’ A vivid early encounter with dinosaurs came when my mother, a lover of classical music, took me to see Walt Disney’s ...


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pp. 44-45

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2. Taxonomy, Cranial Morphology, and Relationships of Parrot-Beaked Dinosaurs(Ceratopsia: Psittacosaurus)

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pp. 21-58

IN 1922, WELL-PRESERVED FOSSILS of the first parrot-beaked dinosaur were discovered in Early Cretaceous horizons in the Gobi Desert of Mongolia. Now referred to a single species, Psittacosaurus mongoliensis, these remains include a growth series from hatchlings to adults. In subsequent years, 15 species have been added to the genus ...

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3. A New Species of Archaeoceratops (Dinosauria: Neoceratopsia) from the Early Cretaceous of the Mazongshan Area, Northwestern China

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pp. 59-67

A NEW SPECIES OF BASAL neoceratopsian dinosaur, Archaeoceratops yujingziensis, is described. The specimen was collected from the Lower Cretaceous Xinminpu Group of the Yujingzi Basin in the Mazongshan area of northwestern China, and is represented by a partial skull, right mandible, and partial postcranial skeleton. ...

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4. A Redescription of the Montanoceratops cerorhynchus Holotype with a Review of Referred Material

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pp. 68-82

THE BASAL NEOCERATOPSIAN Montanoceratops cerorhynchus has historically been interpreted as a close relative of Ceratopsidae by some authors, based on several shared synapomorphies such as the presence of a nasal horn and a reduced laterotemporal fenestra. Only fragments of the skull were recovered with the holotype specimen, however, and were embedded ...

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5. First Basal Neoceratopsian from the Oldman Formation (Belly River Group), Southern Alberta

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pp. 83-90

AN ISOLATED FRONTAL (TMP 87.89.8) referred to Prenoceratops sp. from the Oldman Formation of southern Alberta is a recent addition to the scarce record of North American basal neoceratopsians. TMP 87.89.9 shares the diagnostic characters of Prenoceratops, such as the transverse postorbital ridge and the deep frontal depression. ...

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6. Zuniceratops christopheri: The North American Ceratopsid Sister Taxon Reconstructed on the Basis of New Data

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pp. 91-98

Zuniceratops christopheri Wolfe and Kirkland 1998 is a neoceratopsian dinosaur from the middle Turonian Moreno Hill Formation of west-central New Mexico. The holotype is a partial skeleton (MSM P2101), with additional bonebed material comprising at least seven partial skeletons. The bonebed has yielded numerous disarticulated cranial and postcranial elements, expanding our ...

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7. Horned Dinosaurs (Ornithischia: Ceratopsidae) from the Upper Cretaceous (Campanian)Cerro del Pueblo Formation, Coahuila, Mexico

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pp. 99-116

A COLLABORATIVE FIELDWORK project conducted in the Upper Cretaceous Cerro del Pueblo Formation, southern Coahuila, Mexico, has yielded remains of at least two taxa of ceratopsid dinosaurs from three localities. Although fragmentary and incomplete, these ceratopsid specimens provide important insights into the diversity of dinosaurs in the southernmost portion of North ...

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8. New Basal Centrosaurine Ceratopsian Skulls from the Wahweap Formation (Middle Campanian), Grand Staircase–Escalante National Monument, Southern Utah

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pp. 117-140

A NEW BASAL centrosaurine ceratopsid, Diabloceratops eatoni, is described from the Wahweap Formation (lower to middle Campanian, Upper Cretaceous) of Grand Staircase–Escalante National Monument, southern Utah. The isolated, nearly complete skull is one of the geologically oldest and is the first diagnosable centrosaurine ...

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9. A New Pachyrhinosaurus-Like Ceratopsid from the Upper Dinosaur Park Formation (Late Campanian) of Southern Alberta, Canada

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pp. 141-155

IN 2001, AN ALMOST complete, but disarticulated, adultsized centrosaurine ceratopsid (TMP 2002.76.1) with a pachystotic nasal boss and deeply excavated bosses over the orbits on each postorbital was collected from the transgressive Dinosaur Park Formation (DPF) at Dinosaur Provincial Park (DPP) near Iddesleigh, Alberta. Surficial bone texture indicates that the specimen ...

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10. New Material of ‘‘Styracosaurus’’ ovatus from the Two Medicine Formation of Montana

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pp. 156-168

A PARTIAL SKULL, MOR 492, is attributed to Styracosaurus ovatus Gilmore 1930, hitherto known from only the holotype, USNM 11869, a partial parietal. With the addition of MOR 492, the cranial ornamentation of S. ovatus now includes a tall, erect, long-based nasal horncore and low, rounded supraorbital horncores. ...

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11. A New Chasmosaurine (Ceratopsidae, Dinosauria) from the Upper Cretaceous OjoAlamo Formation (Naashoibito Member), San Juan Basin, New Mexico

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pp. 169-180

Ojoceratops fowleri, a new genus and species of chasmosaurine ceratopsid from the lower Maastrichtian Naashoibito Member (Ojo Alamo Formation), San Juan Basin, New Mexico, is diagnosed by an apomorphic squamosal. Ojoceratops fowleri is presently the only diagnosable ceratopsid ...

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12. A New Chasmosaurine Ceratopsid from the Judith River Formation, Montana

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pp. 181-188

A NEW CHASMOSAURINE CERATOPSID, Medusaceratops lokii, is described based on material collected from a bonebed in the Judith River Formation (Campanian) near Havre, Montana. Originally, all ceratopsid material from the bonebed was referred to the basal centrosaurine Albertaceratops Ryan 2007, the holotype of which was collected from the Oldman Formation of Alberta, Canada. ...

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13. Description of a Complete and Fully Articulated Chasmosaurine Postcranium Previously Assigned to Anchiceratops (Dinosauria: Ceratopsia)

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pp. 189-202

A NEARLY COMPLETE ceratopsid postcranial skeleton with associated skull fragments, long attributed to Anchiceratops, is described. The skeleton is identified as a chasmosaurine, but the paucity of diagnostic cranial material prevents more precise identification. Based on its provenance from unit 2 of the Horseshoe Canyon Formation of Alberta, the skeleton probably pertains to either Anchiceratops or Arrhinoceratops. ...

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14. A New, Small Ceratopsian Dinosaur from the Latest Cretaceous Hell Creek Formation, Northwest South Dakota, United States: A Preliminary Description

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pp. 203-218

A FRAGMENTARY SKULL and skeleton of a small ceratopsian dinosaur from the Hell Creek Formation of South Dakota represents a new taxon of horned dinosaur. This specimen is estimated to have a skull length of approximately 1 m and an approximate total length of 3 m. All preserved elements of the skeleton show ...


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pp. 244-245

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15. Comments on the Basicranium and Palate of Basal Ceratopsians

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pp. 221-233

THE ANATOMY OF BASAL ceratopsians has been studied for more than eight decades, but certain anatomical regions of the skull have been neglected due to problems of preservation and especially of preparation. In the past decade many new specimens of basal ceratopsians, including both psittacosaurids and basal neoceratopsians, have been discovered in China, and a number of new ...

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16. Mandibular Anatomy in Basal Ceratopsia

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pp. 234-250

NUMEROUS DISCOVERIES OF new basal ceratopsian taxa with superb skulls in the past 10 years now make it possible to document the evolution of ceratopsian jaw structure. Further preparation of the specimens after the initial descriptions, especially involving the detachment and removal of mandibles from the skulls, has also revealed new information that was not accessible in initial studies. ...

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17. Histological Evaluation of Ontogenetic Bone Surface Texture Changes in the Frill of Centrosaurus apertus

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pp. 251-263

FRAGMENTARY FRILL ELEMENTS (parietal and squamosal) of Centrosaurus apertus were thin-sectioned for histological analysis in order to determine the microstructural basis of distinctive centrosaurine cranial bone surface textures described by previous authors. The study sample included examples of four textures—long-grained, mottled, smooth, and rugose. Long-grained texture is associated ...

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18. Modeling Structural Properties of the Frill of Triceratops

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pp. 264-270

Triceratops has an unusual parietosquamosal frill among ceratopsids, with a strongly arched profile both in lateral and rostral views, as well as complete absence of parietal fenestrae. Previous workers have suggested that the frill may have had a defensive role, protecting the neck from the horns of other Triceratops or from attacks by predators. ...

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pp. 296-303

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19. New Evidence Regarding the Structure and Function of the Horns in Triceratops (Dinosauria: Ceratopsidae)

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pp. 271-281

ANALYSIS OF A PARTIAL skull of Triceratops provides additional information concerning the structure and function of the taxon’s horns. Skull SUP 9713.0 (Shenandoah University collections) was recovered from the Hell Creek Formation (Upper Cretaceous) near Jordan, Montana. The size and degree of co-ossification of skull elements indicate that the specimen was an adult at time of ...

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20. Evolutionary Interactions between Horn and Frill Morphology in Chasmosaurine Ceratopsians

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pp. 282-292

CHASMOSAURINE DINOSAURS EXHIBIT a wide variation in cranial ornamentation. Their extravagant postorbital horncores and parieto-squamosal frills were almost certainly central to sexual displays and species recognition. We hypothesized that males sparred with their horns during sexual competition for mates and that the use of the postorbital horns in such sparring matches set limits ...

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21. Skull Shapes as Indicators of Niche Partitioning by Sympatric Chasmosaurine and Centrosaurine Dinosaurs

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pp. 293-307

THE FOSSIL RECORD OF ceratopsid dinosaurs demonstrates that postcranially these animals were all quite similar, that centrosaurines and chasmosaurines were of roughly equal body size, and that frequently, several species of these latter two taxa are found preserved in similar stratigraphic positions. A biomechanical analysis of the skulls of ceratopsids using beam theory shows that there are distinct structural differences between centrosaurines and chasmosaurines. ...

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22. The Function of Large Eyes in Protoceratops: A Nocturnal Ceratopsian?

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pp. 308-327

AMONG HERBIVOROUS DINOSAURS, Protoceratops andrewsi is characterized by relatively large eyes. A study of the size of sclerotic rings in extant birds shows that relative eye size correlates with ecological habits: for a given body mass, herbivores, omnivores, and scavengers tend to have modest-sized eyes; diurnal, visually hunting predators have much larger eyes; and nocturnal birds using ...

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23. A Semi-Aquatic Life Habit for Psittacosaurus

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pp. 328-339

Psittacosaurus has been perceived historically as a terrestrial biped that lived in the seasonally dry alluvial to desert paleoenvironments of early Cretaceous Asia. However, because hundreds of specimens are now known from lacustrine deposits in northeastern China, the possibility that Psittacosaurus was a semi-aquatic dinosaur must be considered more seriously than it has been in the past. ...

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24. Habitual Locomotor Behavior Inferred from Manual Pathology in Two Late Cretaceous Chasmosaurine Ceratopsid Dinosaurs, Chasmosaurus irvinensis (CMN 41357) and Chasmosaurus belli (ROM 843)

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pp. 340-354

WE CORRELATE PROGRESSIVE degenerative joint disease of the first digit of the manus with inferred habitual forelimb locomotor behavior of two mature chasmosaurine ceratopsid dinosaurs from the Late Cretaceous of Alberta, Canada. A complete articulated right manus from the holotype of Chasmosaurus irvinensis (CMN 41357) includes a first digit that is markedly abnormal in shape and orientation. ...

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25. Paleopathologies in Albertan Ceratopsids and Their Behavioral Significance

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pp. 355-384

LARGER HORNED DINOSAURS (ceratopsids) are often portrayed in the media, popular science, and paleontological communities as highly aggressive animals, frequently injuring themselves during encounters with predators and intraspecific rivals. Thousands of ceratopsian specimens in the field and in museum collections were examined for examples of paleopathology. ...


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pp. 418-419

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26. An Update on the Paleobiogeography of Ceratopsian Dinosaurs

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pp. 387-404

THE PALEOBIOGEOGRAPHY of ceratopsian (‘‘horned’’) dinosaurs has rarely been analyzed, and usually only in the context of general dinosaur paleobiogeography. In light of new ceratopsian discoveries that have expanded both the temporal and physical ranges of higher-level clades, we review previous work and present new information about the possible dispersal events that must have occurred in this group of dinosaurs. ...

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27. Unraveling a Radiation: A Review of the Diversity, Stratigraphic Distribution, Biogeography, and Evolution of Horned Dinosaurs (Ornithischia: Ceratopsidae)

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pp. 405-427

RECENT DISCOVERIES HAVE greatly expanded our knowledge of the horned dinosaur clade Ceratopsidae. Taxonomically, ceratopsids are currently represented by about 32 species—including 15 species of centrosaurines and 17 of chasmosaurines—an approximate doubling of known diversity in less than 5 years. Phylogenetically, general agreement exists as to the basic structural elements of the ceratopsid tree. ...

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28. A Review of Ceratopsian Paleoenvironmental Associations and Taphonomy

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pp. 428-446

CURRENTLY, MUCH OF THE stratigraphic, paleoenvironmental, and taphonomic data associated with most of the 70 species of ceratopsians lacks detail. Accordingly, there is a clear need for detailed paleoenvironmental and taphonomic work on ceratopsians, especially in the case of relatively new Asian discoveries. Such information is key in evaluating paleobiological and paleoecological aspects and trends within the group. Here, a preliminary ...

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29. Behavioral Interpretations from Ceratopsid Bonebeds

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pp. 447-455

MONODOMINANT CERATOPSID bonebeds represent an important source of information for understanding ceratopsid paleobiology, and monodominant centrosaurine bonebeds are often cited as evidence for herding behaviors and complex social hierarchies for Ceratopsidae. However, caution should be used when applying such interpretations across the entire clade. Ceratopsid bonebeds most commonly contain the remains of centrosaurines, with more than 20 sites representing 8 out of 10 taxa. ...

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30. Paleontology and Paleoenvironmental Interpretation of the Kikak-Tegoseak Quarry (Prince Creek Formation: Late Cretaceous), Northern Alaska: A Multi-Disciplinary Study of a High-Latitude Ceratopsian Dinosaur Bonebed

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pp. 456-477

THE NORTHERN PART OF Alaska contains a number of Cretaceous dinosaur localities that are situated along the Colville River and hosted by the Prince Creek Formation (Campanian to Maastrichtian), a rock unit comprised largely of alluvial/coastal plain sediments shed off the rising Brooks Range to the south. Dinosaur sites include bonebeds like the well-known Liscomb Bonebed, and a more recently discovered dinosaur bonebed, the Kikak- ...

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31. Taphonomy of Horned Dinosaurs (Ornithischia: Ceratopsidae) from the Late Campanian Kaiparowits Formation, Grand Staircase–Escalante National Monument, Utah

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pp. 478-494

A COLLABORATIVE PALEONTOLOGICAL survey conducted by the Utah Museum of Natural History and the Bureau of Land Management in the Upper Cretaceous Kaiparowits Formation, in Grand Staircase–Escalante National Monument, southern Utah, has yielded remains of at least three new ceratopsid dinosaur taxa from multiple localities. Significant ceratopsid specimens excavated and collected from these localities provide the basis of a taphonomic study of ceratopsian deposition in the Kaiparowits Formation. ...

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32. A Centrosaurine Mega-Bonebed from the Upper Cretaceous of Southern Alberta: Implications for Behavior and Death Events

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pp. 495-508

THE HILDA AREA OF southern Alberta preserves the remains of at least 14 discrete monodominant Centrosaurus apertus bonebeds that occur in a single, organic-rich mudstone bed deposited in a coastal-plain interfluve. The identical and traceable stratigraphic positions of the 14 bonebeds allow us to group and interpret them as a single mega-bonebed, covering an estimated area of ...

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33. Insect Trace Fossils Associated with Protoceratops Carcasses in the Djadokhta Formation (Upper Cretaceous), Mongolia

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pp. 509-519

Protoceratops skeletons preserved in the Upper Cretaceous Djadokhta Formation and its correlatives in central Asia are often associated with trace fossils such as borings and diagenetically enhanced burrows in the surrounding rock. An articulated skeleton of a Protoceratops, uncovered at Tugrugiin Shireh, Mongolia, documents the association of both insect borings and casts of insect pupation ...

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34. Faunal Composition and Significance of High-Diversity, Mixed Bonebeds Containing Agujaceratops mariscalensis and Other Dinosaurs, Aguja Formation (Upper Cretaceous), Big Bend, Texas

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pp. 520-537

NEW SEDIMENTOLOGIC AND paleontologic information are presented from multiple, closely associated mixed bonebeds in the Aguja Formation (Campanian) from the Big Bend area of Texas. These bonebeds appear to have been deposited as component parts of channel lags during major flooding events. One of these bonebeds yields the most complete skull of Agujaceratops mariscalensis. ...


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pp. 572-573

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35. Lost in Plain Sight: Rediscovery of William E. Cutler’s Missing Eoceratops

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pp. 541-550

DURING THE FALL AND WINTER OF 1919–1920 and summer of 1920, William E. Cutler, despite ill health and poor weather, succeeded in uncovering and collecting a partial ceratopsian skeleton from quarry 78 in Dinosaur Provincial Park, Alberta. At the time, Cutler was not affiliated with any professional institution, and the specimen was put into storage in Calgary awaiting a buyer. ...

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36. Historical Collecting Bias and the Fossil Record of Triceratops in Montana

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pp. 551-563

Triceratops is one of the most familiar and recognizable Late Cretaceous dinosaurs from North America due to its prominent postorbital and nasal horns and solid frill composed of the parietal and paired squamosals. Complete, undistorted adult Triceratops skulls are found primarily in sandstones and siltstones, which contribute generously to the sedimentary composition of the Hell Creek Formation ...

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pp. 565-567

And there you have it! A remarkable roundup of 36 chapters, plus two extensive articles on the CD-ROM, contributed by 66 ceratopsian researchers and students from around the world. Only a few short years ago, the number of people working on dinosaurs in the entire world was considerably less than the number of authors in this book. In fact, it was very rare during the first century of ceratopsian studies (starting with Cope’s description ...


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pp. 569-624

E-ISBN-13: 9780253007797
Print-ISBN-13: 9780253353580

Page Count: 656
Publication Year: 2010

Series Title: Life of the Past