A New Saurolophine Hadrosaurid \(Dinosauria: Ornithopoda\) from The

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Journal of Systematic Palaeontology Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/tjsp20 A new saurolophine hadrosaurid (Dinosauria: Ornithopoda) from the Campanian of Utah, North America Terry A. Gatesab & Rodney Scheetzc a David Clark Labs, North Carolina State University, Raleigh, NC 27695, USA b North Carolina Museum of Natural Science, 11 W Jones St., Raleigh, NC 27601 c BYU Museum of Paleontology, 1683 N Canyon Rd., Provo, UT 84602, USA Published online: 17 Sep 2014.

To cite this article: Terry A. Gates & Rodney Scheetz (2014): A new saurolophine hadrosaurid (Dinosauria: Ornithopoda) from the Campanian of Utah, North America, Journal of Systematic Palaeontology, DOI: 10.1080/14772019.2014.950614 To link to this article: http://dx.doi.org/10.1080/14772019.2014.950614

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A new saurolophine hadrosaurid (Dinosauria: Ornithopoda) from the Campanian of Utah, North America Terry A. Gatesa,b* and Rodney Scheetzc aDavid Clark Labs, North Carolina State University, Raleigh, NC 27695, USA; bNorth Carolina Museum of Natural Science, 11 W Jones St., Raleigh, NC 27601; cBYU Museum of Paleontology, 1683 N Canyon Rd., Provo, UT 84602, USA (Received 21 February 2013; accepted 17 June 2014)

A new hadrosaurid is described from the Upper Cretaceous Neslen Formation of central Utah. Rhinorex condrupus gen. et sp. nov. is diagnosed on the basis of two unique traits, a hook-shaped projection of the nasal anteroventral process and dorsal projection of the posteroventral process of the premaxilla, and is further differentiated from other hadrosaurid species based on the morphology of the nasal (large nasal boss on the posterodorsal corner of the circumnarial fossa, small protuberences on the anterior process, absence of nasal arch), jugal (vertical postorbital process), postorbital (high degree of ﬂexion present on posterior process), and squamosal (inclined anterolateral processes). This new taxon was discovered in estuarine sediments dated at approximately 75 Ma and just 250 km north of the proliﬁc dinosaur-bearing strata of the Kaiparowits Formation, possibly overlapping in time with Gryposaurus monumentensis. Phylogenetic parsimony and Bayesian analyses associate this new taxon with the Gryposaurus clade, even though the type specimen does not possess the diagnostic nasal hump of the latter genus. Comparisons with phylogenetic analyses from other studies show that a current consensus exists between the general structure of the hadrosaurid evolutionary tree, but on closer examination there is little agreement among species relationships. http://zoobank.org/urn:lsid:zoobank.org:pub:0FDD0FE6-6C20-4838-BD4A-092161179095 Keywords: Hadrosauridae; ornithopod; Cretaceous; Utah; Book Cliffs; Neslen Formation; biogeography; phylogenetics

Introduction underappreciated for their fossil potential. Early in the twentieth century, coal mines in the Book Cliffs were rec- The Cretaceous rocks of western North America have ognized as a repository for dinosaur tracks and have been yielded the highest diversity of hadrosaurid dinosaurs in utilized as a rich data source since (Parker & Balsley the world (Horner et al. 2004; Gates & Evans 2005; 1989). Only two vertebrate skeletal fossil specimens have Prieto-Marquez 2010b). These megaherbivorous ornitho- been reported from these rocks: ﬁrst, Thomson et al. pod dinosaurs are plausibly the most common dinosaur (2013) described a partial tyrannosaurid foot from the fossils found from the Campanian through the terminal Neslen Formation that possesses unique morphological

Downloaded by [78.22.98.228] at 04:53 22 September 2014 Cretaceous, recorded in almost every terrestrial fossilifer- traits, differing from a contemporaneous species ous formation of North America. Even more remarkable (Carr et al. 2011; Zanno et al. 2013) less than 250 km is that during the late Campanian, it appears that hadro- south in the Kaiparowits Formation; and secondly there is saurids generally occupied relatively small geographical a hadrosaurid, also from the Neslen Formation, in which ranges in the Western Interior Basin (WIB) (Gates et al. only extensive skin impressions have been the subject of 2012). publication (Anderson et al. 1999). Here we describe this Whereas the diversity of hadrosaurid dinosaurs has hadrosaurid specimen (BYU 13258) as a new saurolo- been relatively well understood in the northern region of phine genus, as well as discussing its biogeographical, the WIB for several decades, that of the southern region ecological and phylogenetic implications. has remained low until a recent acceleration in discovery (e.g. Gates et al. 2007, 2011; Gates & Sampson 2007; Wagner & Lehman 2009). This surge in identiﬁcation of Geological and taphonomic background new species is due in large part to the exploration of new The Book Cliffs of east-central Utah (Fig. 1) record an sedimentary formations such as the Kaiparowits and Wah- overall regressive sequence of Late Cretaceous marine to weap formations of southern Utah (Gates et al. 2013). The terrestrial rocks. Several formations have been named Book Cliffs of central Utah (Fig. 1), likewise, are greatly within the sequence, and of these the Neslen Formation

*Corresponding author. Email: [email protected]

sandstone together with a precarious ascent to the site led excavators to remove BYU 13528 within a number of manageable sandstone blocks air-lifted by the Utah National Guard. Although the postcranial skeleton of BYU 13528 has yet to be prepared, quarry maps and sandstone blocks suggest that the animal was mostly articulated, with minor dislocation of some tails sections. The body was found lying on its left side with neural spines oriented into the hill. The limbs are missing from the excavated specimen, but if they were associated prior to burial it seems reasonable that they eroded down the steep Figure 1. Map showing Book Cliffs (black fill) and approximate hillside long before its discovery. position (star) of the Rhinorex condrupus gen. et sp. nov. type All geological age approximations of the Neslen Forma- locality within the state of Utah. tion are based on ammonite biostratigraphy from Gill & Hail (1975) and stratigraphical correlations from Kirsch- has proven to be one of the most economically exploited baum & Hettinger (2004). BYU 13528 was found approxi- because of its large, laterally extensive coal beds, the mately 12 m above the base of the Neslen Formation Chesterfield coal zone, which is traceable for 120 km (Anderson et al. 1999), which falls within either the Bacu- (Fisher et al. 1960; Kirschbaum & Hettinger 2004). In lites scotti or Didymoceras nebraskense ammonite zones addition to coal, the formation is comprised of a full com- that Izett et al.(1998) dated to 74.5 § 0.1 Ma and 74.1 § plement of terrestrial to near marine siliciclastic sedi- 0.1 Ma, respectively. In contrast, Cobban et al.(2006) ments, delimited by two regional sequence boundaries favoured older ages for these same biostratigraphical zones (Kirschbaum & Hettinger 2004). (75.56 § 0.11 Ma and 75.19 § 0.28 Ma). Thomson et al. Anderson et al.(1999) described the depositional envi- (2013) published a recalibrated date from Izett et al. ronment of BYU 13258 in detail, which corresponds to (1998) based on recommendations from Renne et al. the Facies Assemblage 2 (lenticular cross-stratified sand- (2010) to 75.15 § 0.29 Ma, similar to the Cobban et al. stone, tabular ripple-laminated sandstones, and inclined (2006) estimation. heterolithic strata) of Kirschbaum & Hettinger (2004). The former authors reported a fining upward sandstone sequence interlaced with siltstone, abundant Teredolites Institutional abbreviations and plant debris (Anderson et al. 1999) that were likely AMNH: American Museum of Natural History, New deposited within a channel near a tidally influenced delta York, USA; BYU: Brigham Young University Museum (Kirschbaum & Hettinger 2004). Firmly indurated of Paleontology, Provo, UT, USA; CMN: Canadian Downloaded by [78.22.98.228] at 04:53 22 September 2014

Figure 2. Sample of skin impressions from Rhinorex condrupus gen. et sp. nov., BYU 13528. Scale bar D 15 mm. New hadrosaurid from the Campanian of Utah 3

Museum of Nature, Ottawa, Ontario, Canada; MOR: Museum of the Rockies, Bozeman, MT, USA; NCSM: North Carolina Museum of Natural Sciences, Raleigh, NC, USA; RAM: Raymond M. Alf Museum, Claremont, CA, USA; ROM: Royal Ontario Museum, Toronto, Ontario, Canada; TCMI: The Children’s Museum of Indi- anapolis, Indianapolis, IN, USA; TMP: Royal Tyrrell Museum of Palaeontology, Drumheller, Alberta, Canada.

Systematic palaeontology

Dinosauria Owen, 1842 Ornithopoda Marsh, 1881 Hadrosauridae Cope, 1870 Saurolophinae Brown, 1914 (sensu Prieto-Marquez 2010c) Rhinorex gen. nov. (Figs 2À7) Type species. Rhinorex condrupus sp. nov. Diagnosis. As for type and only species. Derivation of name. Rhino (Greek) À nose; rex (Latin) À king, in reference to the large nose possessed by this taxon.

Rhinorex condrupus sp. nov. Holotype. BYU 13258, partial, but mostly articulated skeleton and skull. Postcranial elements include partial pelvis and vertebral column.

Diagnosis. Species of saurolophine hadrosaurid with the Figure 3. Rhinorex condrupus gen. et sp. nov. skull in right lat- following autapomorphies: posteroventral process of pre- eral view. A, reconstruction with labelled autapomorphies; B, maxilla possesses slight dorsal expansion on the medial BYU 13528. Abbreviations: nap, nasal anteroventral process; margin at approximately the midpoint; anteroventral pro- ppd, premaxilla posteroventral process dorsal expansion. Scale D cess of nasal resembles a ﬁsh hook being wide, triangular, bar 10 cm. and possessing a small dorsally directed bump. Differen-

Downloaded by [78.22.98.228] at 04:53 22 September 2014 tial diagnosis: Rhinorex condrupus is also distinguished Kritosaurus spp. (slightly inclined posteriorly in Grypo- from other hadrosaurid species by lack of lateral ﬂaring saurus species except specimen MOR 553S-8-26-9-54, on the medial margin of the posteroventral process of the greatly inclined in Edmontosaurus spp., Prosaurolophus premaxilla as in Gryposaurus spp.; vomer with elongated maximus, Saurolophus spp., Maiasaura peeblesorum, excavation at junction of anterior and posterior processes Brachylophosaurus canadensis); deep skull as in Krito- shared with G. monumentensis; posterodorsal margin of saurus navajovius (ratio of dorsoventral height along pos- the circumnarial depression gently incised and located terior margin of quadrate/anteroposterior length from dorsal to the anterior half of the lacrimal as in Gryposaurus posterior quadrate margin to predentary oral margin of spp.; large rugose boss on posterodorsal corner of circum- 0.70 or greater; this measurement is approximated on < narial fossa; small ( 1 cm) bony protuberances along BYU 13258 to be 0.75); temporal bar and frontal inclined anterodorsal margin of nasal, increasing in size posteriorly to approximately 40 to the horizontal as seen in Kritosau- (present on one specimen of Gryposaurus notabilis, rus spp. AMNH 5350); a nasal lacking a solid raised crest on the posterior region of nasal as in Edmontosaurus spp., Acri- stavus gagslarsoni, and a juvenile and ‘adult’ specimen of Gryposaurus notabilis (TMP 80.22.1 and AMNH 5350, Derivation of name. condo (Latin) À bury, in reference respectively); and a jugal with a postorbital process ori- to being buried in rock; rupes (Latin) À cliffs, for being ented perpendicular to the main jugal body as in discovered in the Book Cliffs of Utah. 4 T. A. Gates and R. Scheetz

Occurrence. Neslen Formation, ~12 m from base of for- the anterior infratemporal fenestra margin and the exceed- mation (Anderson et al. 1999) in Thompson Canyon, ingly large (80 mm) height differential between the poste- Grand County, Utah; average age approximately 75.88 rior skull and the dorsal orbital margin, but due to either Ma or 75.15 Ma adjusted from Cobban et al.(2006) and its fragmentary nature or possible preservational deforma- modified by Thomson et al.(2013) from Izett et al. tion, we are reluctant to diagnose the species on these fea- (1998), respectively. Brian Anderson and Roger Wagerle, tures. This is especially given that two other unambiguous students at the University of California at Riverside, dis- unique traits are listed above. Each of these ambiguous covered the site in 1992 while conducting a geological traits is described further below. study of the Book Cliffs area. Together with their advisor Mary Droser, and another graduate student, Reese Barrick from the University of Southern California, they pursued Description and comparisons an excavation permit. William Stokes at the Utah BLM Office suggested they use BYU as a designated repository The following description includes only cranial elements with Ken Stadtman’s collection expertise. because the postcranial elements are currently encased in sandstone at the BYU Museum of Paleontology or at the Description. See below. field locality. The dorsal portion and left side of the skull Remarks. Several other characteristics of the skull are were exposed prior to recovery. As a consequence, many unique to this specimen, such as the vertical orientation of of the left lateral skull elements are eroded or deeply

Table 1. Measurements of the skull BYU 13258, as described in Campione & Evans (2011) and McGarrity et al. (2013). The crest measurements were designed largely for Prosaurolophus (McGarrity et al. 2013) but were co-opted here to make the datasets more com- parable, despite the apparent lack of an ossiﬁed crest. These were taken at the apex of the nasal where crest apex is here assumed to be the point on the nasal directly dorsal to the posteriormost edge of the narial foramen.

Measurement description Length (mm)

Length of the skull measured from the tip of the snout to the back of the quadrate Not preserved Height of the skull measured from the apex of the crest to the maxillary tooth row 300 Length of the crest measured from its rostral inflection point to the back of the crest N/A Length of the lateral extension of the crest measured from the back of the circumnarial depression to the N/A back of the crest CrestÀsnout length measured from the apex of the crest to the tip of the snout 550 Crest to frontal length measured from the apex of the crest to the caudal margin of the nasal ~165 Height of the crest measured from the apex to the ventral margin of the lateral extension of the crest N/A Preorbital length measured from the tip of the snout to the orbital contact between the lacrimal and jugal 470 Circumnarial depression length measured from the reflected margin of the premaxilla to the back of the 485 circumnarial depression Naris length measured from the rostroventral the contact between the nasal and premaxilla to its caudal 341 V-shaped margin Downloaded by [78.22.98.228] at 04:53 22 September 2014 Prenarial length measured from the tip of the snout to the rostral margin of the naris 460 Length of the frontal measured along the midline of the skull from the rostral contact with the nasal and the ~160 caudal contact with the parietal Length of the parietal measured from the rostral contact with the frontals to its caudal margin between the 170 squamosals Length of the postorbital measured from the contact with the prefrontal along the orbital margin to its caudal 200 bifurcation Maximum width of premaxilla measured from the midline of the skull to the lateral margin of the premaxilla Not preserved Length of the jugal measured from the orbital contact with the lacrimal and the dorsal contact with the quadrate Not preserved Minimum height of the jugal measured beneath the orbit 55 Minimum height of the jugal measured beneath the infratemporal fenestra rostral to the jugal flange Not preserved Height of the jugal measured beneath the infratemporal fenestra at the jugal flange Not preserved Height of maxilla measured from its dorsal margin to the maxillary tooth row 120 Length of dentary measured from its rostral margin to the back of the coronoid process of the dentary Not preserved Height of dentary measured from the tooth row to the ventral margin of the dentary Not preserved Length of diastema measured from the rostrodorsal contact with the predentary to the dentary tooth row Not preserved Maximum height of the quadrate measured from its dorsal head to the ventral mandibular condyle Not preserved New hadrosaurid from the Campanian of Utah 5

Figure 4. Unique morphology observed on Rhinorex condrupus gen. et sp. nov., BYU 13528, nasal. A, right lateral view of complete skull of BYU 13528 with rectangles showing locations of BÀE; B, nasal bumps as preserved on left nasal prior to mechanical removal; Downloaded by [78.22.98.228] at 04:53 22 September 2014 arrows show location of each protuberance below; C, close up of anteroventral nasal process with the unique ﬁsh hook morphology; D, dorsal view of nasal posterior region; E, left lateral view of nasal posterior region. Abbreviations: cnb, circumnarial boss; Na, nasal; Pmx, premaxilla. Scale bars: A, D, E D 10 cm; B, C D 5 cm.

weathered, with the prefrontals mostly eroded from the arcuate oral margin and an upturned premaxillary lip. The specimen along with the nasals on the nasofrontal contact, latter feature is less pronounced than in the saurolophine exposing the suture between these two elements. The Edmontosaurus spp. (e.g. NCSM 23119). Angular frontals suffered weathering damage in the form of trans- grooves and ridges line the underside of the oral margin, form cracking and erosion, yet retain enough morphology smaller than those of Gryposaurus monumentensis (Gates for description. See Table 1 for measurements of the skull & Sampson 2007). Dorsally, as in Gryposaurus species following recent morphometric studies of Campione & (Prieto-Marquez 2012), the premaxillary shelf is divided Evans (2011) and McGarrity et al.(2013). into anterior and posterior fossae by a low ridge running posterolaterally from the anterior margin of the nasal fenestra toward the lateral premaxillary oral margin. Both Premaxilla the dorsal and lateral processes display typical Gryposau- The right premaxilla (Fig. 3) is preserved better than rus morphology, including the diagnostic ﬂaring of the the left element, which has slight postfossilization lateral process, although the morphology differs subtly deformation. These elements display a broad, slightly from the latter clade by not protruding laterally, only 6 T. A. Gates and R. Scheetz

anterodorsally. The extent to which the lateral process extends posterodorsally along the face in Rhinorex condrupus is uncertain, but it is likely that it is equivalent to Gryposaurus spp. and Kritosaurus in reaching the lacrimal (Gates & Sampson 2007; Prieto-Marquez 2014), but not the prefrontal.

Maxilla In general aspect, the maxilla (Fig. 3)ofRhinorex condrupus is very similar to species of Gryposaurus, with a broad dorsal process positioned anterior to the anteroposterior midpoint of the element. This taxon is similar to the type specimen of G. notabilis (CMN 2278) in that the large maxillary foramen is exposed slightly more posteriorly, that is, further away from the maxillaryÀpremaxillary contact, than in the type specimen of G. monumentensis (RAM 6797) and a referred specimen of G. notabilis (ROM 873) where the foramen is partially overlapped by the premaxillary lateral process. Gryposaurus latidens has the maxillary foramen positioned more ventrally than in the other Gryposaurus species (Prieto-Marquez 2012). The maxillary foramen is also much larger in R. condrupus compared to other species, which is considered here to be variable among individuals until evidence arises to the contrary. Similar to G. notabilis (Gates & Sampson 2007), the anterodorsal process cannot be seen laterally through the narial foramen. There is a line of several smaller foramina oriented anteroposteriorly from approximately the midline of the maxilla extending posteriorly to lie almost directly ventral to the jugal process. The latter feature of BYU 13285 is smaller than in G. monumentensis (RAM 6797) and a larger specimen of G. notabilis (CMN 2278), more similar in proportions to smaller specimens of G. notabilis (e.g. ROM 873 and TMP 80.22.1). The ectopterygoid shelf extends horizontally to the posterior margin of the maxilla, yielding an ectopterygoid ridge that is more weakly developed than in G. monumentensis Downloaded by [78.22.98.228] at 04:53 22 September 2014 (Gates & Sampson 2007). A row of nutrient foramina arch into the upper third of the maxillary body on the medial side of the element, as is typical with hadrosaurids (Prieto- Marquez 2010c). Dorsal to the medial nutrient foramina the maxillary body swells, with a large overhang forming throughout the articulation with the palatine and pterygoid. Maxillary teeth are covered in a thick iron concretion and therefore description of the morphology is not possible and the exact tooth count is unknown. Yet, given the close similarity to G. notabilis and G. monumentensis, we pre- Figure 5. Dorsal view of the Rhinorex condrupus gen. et sp. dict that R. condrupus will have over 40 tooth positions nov. skull roof, BYU 13528. A, line drawing; B, photograph. and over three teeth within each tooth family. Dotted lines are incomplete edges of elements. Vertical lines in drawing represent rock matrix. Horizontal lines represent broken bone surfaces. Abbreviations: fns, frontonasal suture; fpf, fron- Nasal talÀprefrontal suture; Fr, frontal; Pa, parietal; Po, postorbital; Both nasals are preserved on BYU 13258, although only D Sq, squamosal. Scale bars 10 cm. the anterior half of the nasal (Fig. 3B) is preserved in New hadrosaurid from the Campanian of Utah 7

excellent quality. The anterior process terminates prior to the anterior margin of the narial foramen, as in Gryposau- rus species, Acristavus gagslarsoni, some specimens of Brachylophosaurus, and other more primitive iguano- dontians (Gates & Sampson 2007; Gates et al. 2011). At an early stage of preparation, several protuberances were discovered on the dorsal surface of the anterior nasal process (Fig. 4A), but subsequently were abraded mechani- cally. These protuberances increased in size posteriorly in a similar fashion to Gryposaurus sp. AMNH 5350, yet distinct from this specimen. Due to the poor preservation of the posterior nasal on BYU 13258 it is unclear how far the bumps would extend on the nasal, although the uner- oded surface of the preorbital nasal apex shows that the bumps could have extended that distance. A ventral process of the nasal extends to contact the lacrimal and projects anteriorly, thereby forming the entire posterior and posteroventral borders of the narial foramen. This conﬁguration is seen in all Gryposaurus species and brachylophosaurin hadrosaurids, but the dorsoventrally broad process and dorsally oriented barb gives the entire anteroventral process a ﬁsh hook sem- blance (Fig. 4B) unique to R. condrupus. It should be noted that the type specimen of G. monumentensis (RAM 6797) is missing most of the anteroventral nasal process. The dorsal surface of the nasal does not demonstrate the arched apex as seen on Gryposaurus species. Instead the anterior process breaks from its posterodorsal ascent to proceed nearly horizontally. A diminutive or complete lack of a nasal hump or arch has been documented on G. notabilis specimens such as the juvenile TMP 80.22.1 once assigned to the species G. incurvimanus (Prieto- Marquez 2010c). Also, the larger ‘adult’ specimen AMNH 5350 has been attributed to G. notabilis but lacks a nasal hump (Prieto-Marquez 2010a), looking more similar to Rhinorex.

Downloaded by [78.22.98.228] at 04:53 22 September 2014 Adjacent to the posterior margin of the circumnarial fossa is a large rugose boss that prominently emanates from the nasal. A similar structure was reported for AMNH 5350 by Prieto-Marquez (2010a) with the latter structure being smaller in size and lacking rugose texture. Further examination of other Gryposaurus notabilis specimens (ROM 873, CMN 2278) revealed minor bulging in Figure 6. Palate and braincase of Rhinorex condrupus gen. et the same area. As currently observed, BYU 13258 is the sp. nov., BYU 13528. A, line drawing; B, photograph. The brain- only hadrosaurid to exhibit such a large boss with rugosity case elements are not demarcated because weathering has obliterated the defining sutures. Thick lines surrounding elements are on this region of the nasal. delimiting edges of that element, whereas thin lines are contacts In the postnarial region of the nasal, the element flattens between bone and rock. Dotted lines are incomplete edges of ele- to a thin mediolaterally oriented platform sloping postero- ments. Vertical lines in drawing represent rock matrix. Horizon- dorsally toward the frontal contact. This angled orienta- tal lines represent broken bone surfaces. Note that the dentary tion is different from that seen in other saurolophine was omitted from A but is present at the bottom of B. Abbrevia- tions: CN, cranial nerve; Mx, maxilla; Pal, palatine; Pta, anterior hadrosaurid taxa, which instead possess a relatively hori- process of pterygoid; Ptq, quadrate process of pterygoid; Vo, zontal surface. Configuration of the nasofrontal contact vomer. Scale bar D 10 cm. cannot be discerned on the posterior nasal platform. 8 T. A. Gates and R. Scheetz

Figure 7. Dentary of Rhinorex condrupus gen. et sp. nov., BYU 13528. A, general view medially; B, close up of dentary teeth in medial view. Scale bars D 5 cm.

Jugal Lacrimal The jugal (Fig. 3) is typical for kritosaurin (sensu Prieto- Only the posteroventral section of the right lacrimal is

Downloaded by [78.22.98.228] at 04:53 22 September 2014 Marquez 2014) species (Gates & Sampson 2007; preserved in BYU 13258 (Fig. 3B). As in kritosaurin spe- Prieto-Marquez 2014) with a long pointed anterior process cies the jugal buttress is quite robust (Gates & Sampson ﬁtting partially between the maxilla and lacrimal, a sig- 2007; Prieto-Marquez 2014), protruding posteriorly into moidal ventral margin of the anterior region, and an the orbit as in Saurolophus osborni (e.g. AMNH 5220, enlarged lacrimal process. The triangular posteroventral CMN 8796), Acristavus (MOR 1155), Edmontosaurus process of the anterior region is wider than tall, and over- annectens (e.g. NCSM 23119), some specimens of Bra- all less robust than on G. monumentensis (RAM 6797). chylophosaurus (e.g. MOR 794), and slightly in some Unlike most other species, which have a slightly to exag- specimens of Maiasaura (e.g. ROM 447701). gerated posteriorly inclined postorbital process, this feature is positioned at 90 relative to the body of the jugal in BYU 13528. This condition is more similar to Kritosaurus Frontal sp. (Prieto-Marquez 2014; although one Gryposaurus The frontal (Fig. 5) appears to match the morphology of specimen from the Two Medicine Formation (MOR Kritosaurus navajovius (AMNH 5799) more closely than 553S-8-26-9-54) also shares this condition (A. Prieto- other species of saurolophine in that it is highly angled Marquez pers. comm.). The posteroventral ﬂange does posterodorsally, as opposed to being nearly horizontal. not differ from any Gryposaurus species (Gates & Samp- Erosion of the frontonasal suture reveals what may be the son 2007) and the posterior process is not preserved for centrally positioned fossae that accept posterior processes either the left or right jugal. from the nasals, a characteristic unique to Gryposaurus New hadrosaurid from the Campanian of Utah 9

species (Horner 1992), yet this structure is ambiguous on Edmontosaurus annectens (e.g. NCSM 23119), BYU 13528. The frontal also contributes a small portion Maiasaura (e.g. TCMI 2001.89.2) and Prosaurolophus to the orbital rim. Infiltration of the parietal into the fron- (e.g. CMN 2870) that have median squamosal processes tal is obscured due to erosion. that are inclined posteroventrally. The median processes of BYU 13528 also bend anteriorly towards the sagittal midline. The supraoccipital can be seen just below and Postorbital posterior to the squamosals, offsetting the postcotyloid Weathering has obliterated the external contacts with processes from the squamosals (Fig. 5). This configuration adjacent bones, making it difficult to know exact dimen- does not differ from Gryposaurus species. sions of this element. The orbital margin is rugose, but weathering has likely diminished the true magnitude of bone texturing. Descending ventrally, the jugal process is Infratemporal fenestra generally similar to other kritosaurins, but seems to pro- Rhinorex condrupus is unique in the morphology of the ceed at a more vertical angle, especially at the distalmost entire anterior margin of the infratemporal fenestra, which end where other species tend to have a posteriorly angled when the confluent processes of the jugal and postorbital process (Fig. 3; Gates & Sampson 2007). Ascending are joined, form a straight, vertical margin (Fig. 3). This posterodorsally, the squamosal process meets its counter- differs from all other hadrosaurids in that there is an over- part in a bifurcated contact, forming the temporal bar all trend of anteroventral deflection of the combined jugal that resides at an angle of 40 from the horizontal, as and postorbital processes that form the anterior margin of measured from the right temporal bar. Farke & Herrero the infratemporal fenestra. At its peak, the infratemporal (in press) found that the flexion of the postorbital was fenestra approaches 80 mm higher than the dorsal margin correlated with the maximum width of the skull at the of the orbital cavity. This taller development of the fenes- orbits. BYU 13528 has a skull width of approximately tra compared to the orbit could be the largest height differ- 190 mm, which when applied to the dataset presented by ence within hadrosaurids and is a result of the highly Farke & Herrero (in press), provides a Spearman’s r of inclined temporal bar. Despite the unique fenestra mor- À0.597 and a permutation p-value of 0.053, meaning phology observed in BYU 13258, we are reluctant to con- statistically insignificant correlation between postorbital sider the discussed traits as species-specific apomorphies angulation and skull width. Yet, Farke & Herrero (in until other referred specimens confirm the infratemporal press) acquired a correlation (p-value D 0.039) between configuration and give insights to the posterior margin. these variables without the inclusion of BYU 13528. Therefore, it appears that the angle of ascension seen in BYU 13528 falls outside the variation of Gryposaurus Neurocranium specimens in their study. The anterodorsal corner of the Despite exposure of the endocranium (Fig. 6), little infor- infratemporal fenestra arches more gently than other mation can be gleaned due to weathering and erosion of hadrosaurid species. Finally, we should note that the the element sutures. All cranial nerves are observable, not postorbital angulation is a character shared with Krito- differing in position or relative size compared to other saurus (Prieto-Marquez 2014). We should note there is hadrosaurids (Prieto-Marquez 2010a). Downloaded by [78.22.98.228] at 04:53 22 September 2014 distortion of the posterior skull, in that the left side squamosals are slightly displaced dorsally compared to the right side. This alteration could conceivably depress the Palate right side of the skull, making the true angulation even The palatal elements (Fig. 6) in BYU 13528 are in greater than reported here. complete articulation; however, clear observation of morphology is only available for the vomer. The vomerÀpterygoid articulation is seen, with the anterior Squamosal process of the pterygoid clearly overlapping the posterior The anterior, or postorbital, process of the squamosal process of the vomer. The pterygoid is marginally seen inclines steeply anteroventrally, connecting with the post- overlapping the posterior maxilla and the palatine slightly orbital to form the temporal bar (Fig. 3). The precotyloid anterior. Little can be seen of the palatineÀmaxilla fossa is relatively shallow, not as incised as in Gryposau- contact. rus monumentensis (Gates & Sampson 2007). Little can be described of the quadrate cotylus and the precotyloid and postcotyloid processes due to breakage. Medially, the Vomer squamosals do not appear to contact, but the sagittal Paired vomers are preserved in articulation within BYU region is slightly damaged. The median processes form an 13258, but only the left is fully observable (Fig. 6). The anteroposteriorly protracted overhang, which differs from elongated paddle-shape of the posterior region of the 10 T. A. Gates and R. Scheetz

vomer is nearly identical to that seen in UMNH VP the genera Kritosaurus, Wulagasaurus and Edmontosau- 13970, a specimen referred by Gates & Sampson (2007) rus. Firstly, Kritosaurus is placed by both Prieto-Marquez as a juvenile Gryposaurus monumentensis, as well as the (2012) and Godefroit et al.(2012) near the genus Grypo- type specimen of that species, RAM 6797. Noting the var- saurus, yet here the analysis placed it as the most basal iation described in Gates & Sampson (2007), it seems that saurolophine clade. Next, Wulagasaurus is a taxon known the vomer is a potentially diagnostic element, at least at from few skull elements and has been placed toward the the genus level, and possibly to species level. The vomer base of Saurolophinae (Godefroit et al. 2012) or at the present in BYU 13258 possesses an excavated vomer base of a clade containing the Kritosaurini (sensu Prieto- body. The latter specimen maintains complete closure Marquez (2012)). In this study Wulagasaurus is placed at around the entire excavation, unlike RAM 6797 that has the base of a clade containing Brachylophosaurini (sensu the lower margin of the vomer also removed. UMNH VP Gates et al. 2011), as posited by Xing et al.(2012). 13970 has a subcircular excavation in the middle of the Prieto-Marquez (2012) placed Edmontosaurus as a basal element with all margins closed, which means that either clade within Saurolophinae, whereas this study and Gode- the vomer undergoes considerable reconstruction through froit et al.(2012) place the genus nearer Prosaurolophus. ontogeny, the specimen has been misidentified, or there is The Bayesian analysis was run in MrBayes 3.2 (Ron- extreme variation in this element among individuals. quist et al. 2012) with 10 million generations, sampling every 5000 generations, standard data, equal and variable rates, and 25% burn-in. A complete list of analysis set- Dentary tings can be found in the Supplemental Material. The tree The dentary is broken through the anterior half (Fig. 3). produced through the variable rate model (average stan- The posterior half is robust, as seen in other Gryposaurus dard deviation of split frequencies from last one million species (Gates & Sampson 2007), with the posteroventral generations equalled 0.008; harmonic mean À3497.86; portion of the coronoid process articulated with the suran- Fig. 9) did not differ substantially from that of a fixed gular. The remainder of the right coronoid is covered with (equal) rate model (harmonic mean À3499.18) in topol- matrix, whereas the left coronoid shows a typical hadro- ogy. That said, both the fixed rate and variable rate trees saurid morphology of anteroposterior expansion with are superficially similar to the variable model of Prieto- exclusion of the surangular from the distalmost region. Marquez (2010c) in that Lambeosaurinae is nested within Dentary teeth (Fig. 7) are ornamented with a single the Saurolophinae instead of being a sister clade, thereby median ridge, posteriorly offset, and mostly straight (only making Saurolophinae paraphyletic. This topology is a small portion are distally curved). At least three, and extremely different from that of the parsimony analysis, likely up to five, make up each tooth family. and given the current fossil record, seems quite unlikely. Other small variations are present between these trees, yet given that this avenue of hadrosaurid phylogenetic inquiry Phylogenetic analysis is still new, we feel that subtle discrepancies should best be discussed pending further investigation of model Both a parsimony and Bayesian phylogenetic analysis parameters on varying datasets. Evans (2010) analyzed a were performed on the data matrix included in the Supple- phylogenetic dataset through Bayesian algorithms, and

Downloaded by [78.22.98.228] at 04:53 22 September 2014 mental Material. This matrix consists of 50 OTUs, 236 even though that dataset focused only on lambeosaurine characters taken mainly from Prieto-Marquez (2010c), taxa, expansion of this alternative data to saurolophines using Iguanodon bernissartensis as the outgroup. The par- may provide more insight to the non-traditional results simony analysis was performed in TNT (Goloboff et al. presented here and in Prieto-Marquez (2010c). 2003) with 1000 Wagner tree replicates and tree bisection reconnection (saving 100 trees per replicate). The 120 most parsimonious trees obtained a tree length of 682 Discussion with a Consistency Index of 0.498 and Retention Index of 0.793. Biostratigraphical context Each saved individual tree yielded a monophyletic Following the North American hadrosaurid biostrati- Gryposaurus clade, with Rhinorex condrupus outside of graphical framework of Gates et al.(2012, ﬁg. 4, Rhinorex the genus. G. latidens is the next taxon up the tree, with condrupus labelled as Gryposaurus sp. nov.) and the older G. notabilis and G. monumentensis as sister taxa. approximate ages for the type locality of R. condrupus, Although retained in the majority rule tree, the strict con- this new species lived at approximately the same time as sensus tree collapses the Gryposaurus clade (Fig. 8). Gryposaurus notabilis and/or Gryposaurus monumenten- Notable differences between the trees recovered in this sis, Prosaurolophus maximus and an undescribed taxon analysis compared to the recent studies of Prieto-Marquez from Big Bend National Park in Texas. Alternatively, if (2012) and Godefroit et al.(2012) involve the position of the younger ages are considered, the only known New hadrosaurid from the Campanian of Utah 11

Figure 8. Maximum parsimony consensus trees. A, majority rule; B, strict consensus. Numbers are Bremer support values. Iguanodon Downloaded by [78.22.98.228] at 04:53 22 September 2014 bernissartensis was used as the outgroup.

hadrosaurid taxon that may have lived simultaneously 2012, 2013), were found only 250 km south-west, in with R. condrupus is Prosaurolophus maximus (McGarr- southern Utah. Due to the dating uncertainty for the R. ity et al. 2013). North American hadrosaurid taxa are rela- condrupus type locality, it is uncertain whether this new tively sparse for the younger time period, making this taxon existed contemporaneously with the aforemen- chronozone especially important for understanding shifts tioned Gryposaurus species. If so, this is one of the most in hadrosaurid diversity during the Campanian. dramatic cases of dinosaurian habitat partitioning recorded; especially when one considers the relatively short distance between occurrences in relation to the large Biogeographical and environmental context body size of these species. Rhinorex condrupus was discovered in the Book Cliffs of Sediments of the Kaiparowits Formation in southern central Utah, within estuarine sediments deposited by a Utah record a more upland, alluvial-style swamp environ- river on the margin of the Western Interior Seaway ment compared to the coastal, tidally inﬂuenced swamp of (Anderson et al. 1999). This is the ﬁrst hadrosaurid spe- the Book Cliffs. One could speculate that such differences cies known from central Utah, whereas two species of in habitat could have created different plant communities Gryposaurus, G. sp. and G. monumentensis (Gates et al. that may have led to the segregation of these hadrosaurs. 12 T. A. Gates and R. Scheetz

However, without better assessment of the local plant closer to and slightly hidden by the lateroventral process communities and more accurate dating of the Neslen For- of the premaxilla (RAM 6797, ROM 873, but see the mation, and the R. condrupus type locality in particular, slightly more lateral position of CMN 2278), whereas on such ecological speculation has no foundation. Nonethe- R. condrupus and Kritosaurus horneri (BYU 12950; less, it is worth noting that R. condrupus is the first of the Prieto-Marquez 2014) the foramen is positioned well pos- Gryposaurus clade to be found in a marine influenced terior to the contact with the posterolateral premaxillary environment (although Prieto-Marquez (2014) assigned process. Secondly, the postorbital process of the jugal is YPM-PU 16970 from the Bearpaw Shale to Gryposaurus oriented vertically, as opposed to slightly inclined as in sp.), and that the previous hypothesis that members of the Gryposaurus species (Gates & Sampson 2007). Kritosau- genus were more likely generalist feeders (Gates & rus species have a vertical postorbital process (Prieto- Sampson 2007) possibly gains support given an increase Marquez 2014). Despite Kritosaurus spp. and Gryposau- in the breadth of environmental preferences seen in hadro- rus spp. resolving in different clades on the cladograms saurids exhibiting a ‘gryposaur’-type morphology. presented in Figures 8 and 9, these taxa do seem closely Rhinorex is not the first hadrosaurid taxon to be found related based on gross morphology, and R. condrupus near marine sediments (see Horner et al. 2004 for list of superficially seems to be even more similar to Kritosaurus taxa). Kritosaurus (sensu Prieto-Marquez 2014) speci- spp. than other Gryposaurus species. Interestingly, if the mens from the Cerro del Pueblo Formation are also pre- later radiometric date is taken for the R. condrupus local- served in nearly identical environments (Eberth et al. ity, then this places the taxon within a small window of 2004). Prieto-Marquez (2014) supported previous phylo- time from which no hadrosaurids are known from the genetic hypotheses that the genera Kritosaurus and Gry- south-western USA, just after the last occurrence of G. posaurus are closely related, which may indicate a similar monumentensis (Gates et al. 2013) and prior to the first habitat preference for R. condrupus and Kritosaurus sp. occurrences of Kritosaurus in the Kirtland Formation around 73.5 Ma (Gates & Evans 2005; Gates et al. 2012).

Evolutionary implications In addition to the environmental similarities mentioned Hadrosaurid phylogenetic conﬂict above, there are a couple of features of the Rhinorex con- Over the past decade, hadrosaurid phylogenetic informa- drupus skull that generally differ from Gryposaurus spe- tion has increased dramatically through the naming of cies but are present in Kritosaurus specimens. First, the many new species and increasing the number of phyloge- large anterior maxillary foramen is generally positioned netic traits used in analyses. The rapid inﬂux of traits Downloaded by [78.22.98.228] at 04:53 22 September 2014

Figure 9. Bayesian phylogenetic consensus tree with uncalibrated branch lengths. Iguanodon bernissartensis was used as the outgroup. Numbers are branch length values. New hadrosaurid from the Campanian of Utah 13

Figure 10. Supernetwork of parsimony strict consensus trees obtained from this study, Prieto-Marquez (2010c) and Godefroit et al. (2012).

within published phylogenies has also produced as many Gryposaurus spp. and Prosaurolophus are labile on the conflicting cladistic hypotheses as there are publications. tree, but the taxa within those clades are relatively stable. Here we utilize the program SplitsTree 4.13.1 (Huson & There was minor conflict in the placement of Wulagasau- Bryant 2006) to easily visualize areas of conflicting posi- rus, and the relationships within the Brachylophosaurini.

Downloaded by [78.22.98.228] at 04:53 22 September 2014 tion of terminal taxa within sets of phylogenetic trees. SplitsTree 4.13.1 produces networks from inputted phylogenetic trees in order to identify taxa that change position throughout the selection of trees as well as mapping the Conclusions changes in position. Those OTUs that do not move around the tree will be represented by a single line, whereas those Here we present Rhinorex condrupus, a new saurolophine that do move will have multiple lines linked to other taxa hadrosaurid from the Upper Cretaceous Neslen Formation with which they are found through the sampled trees. Split of central Utah. This species is diagnosed on a unique fea- networks do not necessarily convey any evolutionary rela- ture of the nasal, the anteroventral nasal process with a tionships in the way phylogenetic trees are designed small dorsal projection that gives an overall ‘fish hook’ (Huson & Bryant 2006). We used trees derived from the appearance to the area, as well as the lateroventral process strict consensus analyses above and those of Prieto- of the premaxilla displaying a dorsal exaggeration. Other Marquez (2010c) and Godefroit et al.(2012) to test for characters that aid differentiation of this species are the conflict between presented tree topologies. lack of an osseous nasal ornamentation, a large boss on Most iguanodontian relationships remained stable the circumnarial fossa, a series of protuberances rising on through the trees (Fig. 10); however, severe conflict was the medial margin of the nasal, and a squamosal that rises found within the Saurolophinae. The web of connections at a steeper angle compared to most other hadrosaurid seen within the clade demonstrates that subclades close to species. 14 T. A. Gates and R. Scheetz

Rhinorex is found in a coastal, tidally influenced envi- Gillette (ed.) Vertebrate Paleontology in Utah. Utah ronment, which when considered with the other environ- Geological Survey, Salt Lake City. mental and geographical occurrences (ranging from Carr, T. D., Williamson, T. E., Britt, B. B. & Stadtman, K. 2011. Evidence for high taxonomic and morphologic tyran- southern Canada through Texas and arid uplands through nosaurid diversity in the Late Cretaceous (late Campanian) coastal plain) of the genus Gryposaurus adds additional of the American southwest and a new short-skulled tyranno- evidence to the hypothesis that species of this skull mor- saurid from the Kaiparowits Formation of Utah. Naturwis- phology could have been more generalist feeders (Gates senschaften, 98, 241À246. & Sampson 2007). Not tackled, but of critical importance Campione, N. E. & Evans, D. C. 2011. Cranial growth and variation in edmontosaurs (Dinosauria: Hadrosauridae): implica- for future studies of feeding habits and cranial ornamenta- tions for latest Cretaceous megaherbivore diversity in North tion in hadrosaurids, is the supposed difficulty of main- America. PLoS One, 6(9), e25186. taining nearly identical cranial ornamentation, which Cobban, W. A., Walaszczyk, I., Obradovich, J. D. & should act as a uniting factor, while at the same time dif- McKinney, K. C. 2006. A USGS zonal table for the Upper ferentiating into different species with seemingly different Cretaceous Middle Cenomanian-Maastrichtian of the Western Interior of the United States based on ammonites, environmental preferences. inoceramids, and radiometric ages. U.S. Geological Survey Finally, new parsimony and Bayesian phylogenetic Open-File Report 2006-1250, 46 pp. analyses demonstrate similarity with prior analyses in Eberth, D. A., Delgado-de Jesus, C. R., Lerbekmo, J. F., basic respects but differ with regard to the placement of Brinkman, D. B., Rodrıguez-de la Rosa, R. A. & certain mobile taxa. As shown through the use of consen- Sampson, S. D. 2004. Cerro del Pueblo Fm (Difunta Group, Upper Cretaceous), Parras Basin, southern Coahuila, sus tree networks, within individual studies those mobile Mexico: reference sections, age, and correlation. Revista taxa include basal hadrosauroids and higher order taxa Mexicana de Ciencias Geologicas , 21, 335À352. with sparser skeletal remains. Combining the phyloge- Evans, D. C. 2010. Cranial anatomy and systematics of Hypa- netic trees from multiple analyses into a single supertree crosaurus altispinus, and a comparative analysis of skull network shows that overall, little consensus exists growth in lambeosaurine hadrosaurids (Dinosauria, Ornithi- schia). Zoological Journal of the Linnean Society, 159, between hadrosaurid phylogenies. 398À434. Farke, A. A. & Herrero, L. in press. Variation in the skull roof of the hadrosaur Gryposaurus illustrated by a new specimen Acknowledgements from the Kaiparowits Formation (late Campanian) of southern Utah. Pp. 000À000 in D. A. Eberth & D. C. Evans (eds) We thank Ken Stadtman for insight into the original excava- Hadrosaurs. Indiana University Press, Indianapolis. tion and location of the site; Jeff Higgerson for relocating the Fisher, D. J., Erdmann, C. E. & Reeside, J. B. 1960. Cretaceous and Tertiary formations of the Book Cliffs, excavation site; Austin Andrus, Shamra Smith and Josie New- Carbon, Emery, and Grand counties, Utah and Garfield and bold for initial preparation; Eric Lund for help relocating the Mesa counties, Colorado. U.S. Geological Survey Profes- excavation site and preparation expertise; Lindsay Zanno and sional Paper, 332, 80. Lisa Hertzog for final preparation. We thank citizen scientists Gates, T. A. & Evans, D. C. 2005. Biogeography of Campanian Andrea, Claire, and Joshua for their help naming this dinosaur. hadrosaurid dinosaurs from western North America. Pp. 33À39 in D. R. Braman, F. Therrien, E. B. Koppelhus & Virginia Greene illustrated the reconstruction and palate. Fund- W. Taylor (eds) Dinosaur Park Symposium short papers, ing was provided by Patrick O’Connor and the Ohio Univer- abstracts, and programs. Royal Tyrrell Museum of Paleon- tology, Drumheller, Alberta.

Downloaded by [78.22.98.228] at 04:53 22 September 2014 sity Heritage College of Osteopathic Medicine Postdoctoral Fellowship (to TAG) and the National Geographic Waitt Gates, T. A., Horner, J. R., Hanna, R. R. & Nelson, C. R. Foundation [#W246-12] (to TAG). 2011. New unadorned hadrosaurine hadrosaurid (Ornitho- poda: Dinosauria) from the Campanian of North America. Journal of Vertebrate Paleontology, 31, 798À811. Gates, T. A., Lund, E. K., Boyd, C. A., DeBlieux, D. D., Titus, A. L., Evans, D. C., Getty, M. A., Kirkland, J. I. & Eaton, Supplemental data J. G. 2013. Ornithopod dinosaurs from the Grand Staircase- Escalante National Monument region, Utah and their role in Supplemental material for this article can be accessed at: paleobiogeographic and macroevolutionary studies. À http://dx.doi.org/10.1080/14772019.2014.950614 Pp. 463 481 in A. L. Titus & M. A. Loewen (eds) At the top of the Grand Staircase: The Late Cretaceous of southern Utah. Indiana University Press, Indianapolis. Gates, T. A., Prieto-Marquez, A. & Zanno, L. E. 2012. Moun- tain Building Triggered Late Cretaceous North American References Megaherbivore Dinosaur Radiation. PloS One, 7(8), e42135. Anderson, B. G., Barrick, R. E., Droser, M. L. & Stadtman, Gates, T. A. & Sampson, S. D. 2007. A new species of Grypo- K. L. 1999. Hadrosaur skin impressions from the Upper Cre- saurus (Dinosauria: Hadrosauridae) from the Late Campa- taceous Neslen Formation, Book Cliffs, Utah: morphology nian Kaiparowits Formation. Zoological Journal of the and paleoenvironmental context. Pp. 295À301 in D. D. Linnean Society, 151, 351À376. New hadrosaurid from the Campanian of Utah 15

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