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Review of Hadrosauridae (Dinosauria, Ornithischia) from the San Juan Basin, New Mexico

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... Though poorly preserved, the type and only previously known specimen of P. cyrtocristatus possesses the distinct crest morphology that easily differentiated the species from either P. walkeri or P. tubicen, yet this trait also was the sole source of evidence for suggesting sexual dimorphism within the genus (Hopson, 1975;Williamson, 2000). A consequence of the sexual dimorphism hypothesis is that if FMNH P-27393 was a sexual dimorph of either of the two long crested species, that would mean that the name P. cyrtocristatus would ergo be a junior synonym of a different species. ...
... Most recent systematic revisions of the genus Parasaurolophus have discussed the validity of Parasaurolophus cyrtocristatus and at least tentatively considered the taxon valid (Sullivan & Williamson, 1999;Horner, Weishampel & Forster, 2004;Evans, 2007Evans, , 2010Prieto-Márquez, 2010). Confusingly, Williamson (2000) argued that it is most parsimonious to regard P. cyrtocristatus as a subjective junior synonym of P. tubicen, yet at the same time referred BYU 2467 and UCMP 143270 to P. cyrtocristatus later in the same paragraph. In this study, new material affirms the validity of P. cyrtocristatus. ...
... A second specimen, UCMP 143270 ( Figs. 12 and 13), constitutes a well preserved and complete crest with articulated upper cranium. Sullivan & Williamson (1999) and Williamson (2000) referred both BYU 2467 and UCMP 143270 to P. cyrtocristatus, based on crest curvature. New preparation and study of UCMP 143270 together with the discovery of DMNH EPV.132300 gives the opportunity to test the identification of the Kaiparowits taxon with the newly described characteristics of P. cyrtocristatus since more recent studies have shown that crest curvature is allometric. ...
Article
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For nearly 60 years, skulls of Parasaurolophus species have been differentiated primarily on the basis of crest shape rather than on unique morphologic characters of other cranial elements. Complicating matters is the fact that crests dramatically change shape throughout ontogeny. Without a complete growth series, it has become difficult to assess the taxonomic distinctness of each species through the lens of allometric growth. Parasaurolophus cyrtocristatus has proven to be especially troublesome to assess because of the poorly preserved nature of the type and only skull. A new, partial skull from the Fossil Forest Member of the Fruitland Formation—the same geologic unit as the type specimen—is the first opportunity to re-diagnose this species as well as redefine the genus with many new traits. An undescribed, short-crested subadult skull from the Kaiparowits Formation of Utah previously assigned to cf. P. cyrtocristatus allows detailed comparisons to be made between the unnamed Utah taxon and the material of this species from the type locality. We find that several characteristics of the squamosal, supraoccipital, and premaxilla shared between the referred skull and the type skull are unique to P. cyrtocristatus (senso stricto) within the genus, irrespective of the overall crest shape. A phylogenetic analysis that includes six new characters posits that P. cyrtocristatus and P. tubicen are sister taxa, and that the latter does not share a closest common ancestor with the long-crested P. walkeri as previously hypothesized. This result helps to explain why both taxa are found in northeastern New Mexico, USA and in sequential geologic units (Fruitland Formation and Kirtland Formation, respectively). Additionally, the exquisitely preserved new skull provides the first opportunity to unequivocally identify the osteological make-up of the Parasaurolophus cranial crest. Unlike in previous reconstructions, the crest composition in Parasaurolophus follows what is seen in other lambeosaurines such as Corythosaurus , where the dorsal process of the premaxilla dominates the crest, with the nasal forming 80% of the ventral paired tubes, and the lateral premaxillary process acting a lateral cover between the dorsal and ventral tubes. The skull of P. cyrtocristatus is still incompletely known, so more complete material will likely reveal new features that further differentiate this species and aid in determining the pace of ornamental crest evolution.
... For over a century, vertebrate fossils have been collected from the San Juan Basin (SJB) of New Mexico (upper Campanian, Late Cretaceous; Fig. 1; Williamson, 2000). Although the hadrosaurid record of the SJB pales in comparison to the well-preserved specimens and growth series from the northern United States and Canada, many enigmatic taxa have been discovered. ...
... In contrast to specimens from northwestern North America, many of the hadrosaurid specimens collected in the San Juan Basin are referable only to the subfamily level (Williamson, 2000). Although the specimens of this collection are isolated, they are complete and of better quality than many excavated in the San Juan Basin. ...
... Although many of these specimens show affinities to Kritosaurini, they do not conclusively belong to Kritosaurus navajovius, suggesting that the saurolophine diversity in the SJB could be greater than currently recognized and further suggesting that the proposed cladogenesis within hadrosaurids occurred as a result of Laramide tectonic events (Gates et al., 2012). The dominance of saurolophines in this collection of specimens reflects the general picture of diversity previously recognized in this part of the section (Williamson, 2000;Sullivan and Lucas, 2014). However, comparisons of overall hadrosaurid diversity in the SJB and northern North America remain difficult due to the effect of preservation. ...
Article
The Field Museum of Natural History collection contains several isolated hadrosaurid specimens collected by Charles H. Sternberg from the lower Kirtland Formation of the San Juan Basin, New Mexico, that have been previously overlooked. Cranial elements described herein consist of a dentary and three jugals while appendicular material is limited to two humeri and two pubes. Many of the specimens preserve taxonomically informative characters that show strong affinities with Kritosaurini but are distinct from Kritosaurus navajovius (Brown, 1910) suggesting that the saurolophine-dominated San Juan Basin diversity is greater than currently recognized. Future examination of currently unprepared material will add to our developing understanding of the ambiguous hadrosaurid diversity of the San Juan Basin.
... Hadrosauridae: Five hadrosaurids have been named from the Fruitland/Kirtland formations, three hadrosaurines-Kritosaurus navajovius, Anasazisaurus horneri, Naashoibitosaurus ostromiand two lambeosaurines-Parasaurolophus cyrtocristatus and Parasaurolophus tubicen (Brown, 1910;Hunt and Lucas, 1993;Ostrom, 1961;Wiman, 1931). Hunt and Lucas (1993) suggested that K. navajovius is a nomen dubium and that A. horneri and N. ostromi are distinct, but Williamson (2000) concluded that K. navajovius is valid and that A. horneri and N. ostromi are junior subjective synonyms of K. navajovius. In addition, Williamson (2000) synonymized P. cyrtocristatus with P. tubicen, and misrepresented the conclusions reached by Sullivan and Williamson (1999) regarding the coexistence of P. cyrtocristatus and P. tubicen. ...
... Hunt and Lucas (1993) suggested that K. navajovius is a nomen dubium and that A. horneri and N. ostromi are distinct, but Williamson (2000) concluded that K. navajovius is valid and that A. horneri and N. ostromi are junior subjective synonyms of K. navajovius. In addition, Williamson (2000) synonymized P. cyrtocristatus with P. tubicen, and misrepresented the conclusions reached by Sullivan and Williamson (1999) regarding the coexistence of P. cyrtocristatus and P. tubicen. Mere sympatry of the two species, which has not yet been demonstrated, is not a conclusive argument for synonymy. ...
Conference Paper
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The Kirtlandian is a new land-vertebrate “age” (LVA) representing 2.9 million years of Campanian time that fills a long-standing biochronologic gap between the Judithian and Edmontonian LVAs. This new LVA is characterized by the vertebrate fossil assemblages of the Fruitland and Kirtland formations, San Juan Basin, New Mexico, and the ceratopsine dinosaur Pentaceratops sternbergii is the principal index fossil. The Kirtlandian is defined as the time between the first appearance of Pentaceratops sternbergii (= end of the Judithian) and the first appearance of Pachyrhinosaurus canadensis (= beginning of the Edmontonian). Characteristic Kirtlandian vertebrates include: Melvius chauliodous, Denazinosuchus kirtlandicus, Kritosaurus navajovius, Anasazisaurus horneri, Naashoibitosaurus ostromi, Parasaurolophus tubicen, P. cyrtocristatus, Nodocephalosaurus kirtlandensis, and Prenocephale goodwini.
... Downloaded from (Fig. 1A), and all but one of these identifications is based on a single bone specimen. Some of the older collections may contain additional Ojo Alamo dinosaurs, but only the specimens that could unquestionably be placed within the Ojo Alamo Sandstone are listed: ornithomimid, indeterminate; dromaeosaurid, indeterminate; saurornithoidids, indeterminate; ?Alber-The work of Hunt and Lucas (1992) has been updated, principally by and Williamson (2000). The following list of dinosaurs from the Ojo Alamo Sandstone (Naashoibito Member of the Kirtland Formation) from Lucas et al. (2000, p. 88), is considered to be the most accurate now available. ...
... These studies suggest that the evolving physiogeography of the Western Interior Basin, coupled with changing climate during the Late Cretaceous, resulted in periodic physical or ecological barriers to vertebrate movement. Other studies (e.g., Vavrek and Larsson, 2010;Wick and Lehman, 2013;Lucas et al., 2016;Berry, 2018) dispute a hypothesis of Western Interior Basin biomes altogether, typically over concerns regarding sampling biases and/or cladotaxonomic issues (e.g., Williamson, 2000;Longrich., 2014;Lucas et al., 2016;Berry, 2018), asynchronous temporal comparisons Lucas et al., 2016;Fowler, 2017), or lack of perceived evidence for a geologic or climatic barrier (e.g., Wolfe and Upchurch, 1987;Amiot et al., 2004;Longrich, 2014;Upchurch et al., 2015, Lucas et al., 2016Berry, 2018). ...
Article
The Upper Cretaceous Western Interior Basin of North America provides a unique laboratory for constraining the effects of spatial climate patterns on the macroevolution and spatiotemporal distribution of biological communities across geologic timescales. Previous studies suggested that Western Interior Basin terrestrial ecosystems were divided into distinct southern and northern communities, and that this provincialism was maintained by a putative climate barrier at ∼50°N paleolatitude; however, this climate barrier hypothesis has yet to be tested. We present mean annual temperature (MAT) spatial interpolations for the Western Interior Basin that confirm the presence of a distinct terrestrial climate barrier in the form of a MAT transition zone between 48°N and 58°N paleolatitude during the final 15 m.y. of the Cretaceous. This transition zone was characterized by steep latitudinal temperature gradients and divided the Western Interior Basin into warm southern and cool northern biomes. Similarity analyses of new compilations of fossil pollen and leaf records from the Western Interior Basin suggest that the biogeographical distribution of primary producers in the Western Interior Basin was heavily influenced by the presence of this temperature transition zone, which in turn may have impacted the distribution of the entire trophic system across western North America.
... Yet little has been published on trace fossils (footprints and coprolites) from the Fruitland, Kirtland and Ojo Alamo formations. Fossilized hadrosaur footprints from the Fruitland Formation have been previously reported by Wolberg et al. (1988), Williamson (2000), Hunt andLucas (1993, 2003), and most recently by Lucas et al. (2011). Hunt (1991) hypothesized that the scarcity or absence of coprolites of large reptiles and dinosaurs in the Fossil Forest region (Fruitland-Kirtland formation transition) was due to efficient digestive processes that destroyed all traces of bones and teeth. ...
Article
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Abstract—Coprolites from the Upper Cretaceous Fruitland, Kirtland and Ojo Alamo formations in the vertebrate paleontology collection of the State Museum of Pennsylvania consist of different forms that are identified as morphotypes A-G. These coprolites are attributed to carnivorous vertebrates (fishes, turtles and crocodylians). At least four unique Upper Cretaceous coprolite morphotypes (B, D, F and G) are recognized. Four different surface textures are also recognized (smooth, slightly blistered, wrinkled and striated), but only partially coincide with the morphotypes. Bone inclusions are common in about half of the coprolites, and one contains the ?astragalus and ?calcaneum of an anuran, the first record of an anuran in a Late Cretaceous coprolite. A large, irregular bony mass containing large and small fragments of a ?scapula blade, ?vertebral centra and partially digested bone is identified as a probable tyrannosauroid coprolite. The large ?scapula blade fragment appears to be from a sub-adult hadrosaurid. This specimen potentially represents the third record of a carnosaur coprolite, and the first from the United States and New Mexico.
... These studies suggest that the evolving physiogeography of the Western Interior Basin, coupled with changing climate during the Late Cretaceous, resulted in periodic physical or ecological barriers to vertebrate movement. Other studies (e.g., Vavrek and Larsson, 2010;Wick and Lehman, 2013;Lucas et al., 2016;Berry, 2018) dispute a hypothesis of Western Interior Basin biomes altogether, typically over concerns regarding sampling biases and/or cladotaxonomic issues (e.g., Williamson, 2000;Longrich., 2014;Lucas et al., 2016;Berry, 2018), asynchronous temporal comparisons Lucas et al., 2016;Fowler, 2017), or lack of perceived evidence for a geologic or climatic barrier (e.g., Wolfe and Upchurch, 1987;Amiot et al., 2004;Longrich, 2014;Upchurch et al., 2015, Lucas et al., 2016Berry, 2018). ...
... Fossils found within CHCU: Only a few trace fossils have been found in the Kin Ya'a unit (Tweet et al. 2009) Fossils found elsewhere: Some of the beds are bioturbated, indicating animal activity (Robertson 1986). The Gibson Coal Member has yielded pollen, spores, coal (Tschudy 1976), plant debris, petrified wood, leaf impressions (Kirk and Zech 1977), and some fragmentary dinosaur material (Lucas et al. 2000), including a partial lower jaw from a hadrosaur dinosaur (Williamson 2000). The Dalton Sandstone also contains bioturbated beds and trace fossils in tidal or estuarine sediments which include Ophiomorpha (burrows from shrimp-like crustaceans), Thalassinoides (cylindrical, horizontal branching burrows), and Skolithos (tube-like vertical burrows). ...
Technical Report
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This National Park Service report is the public version of the Chaco Culture National Historical Park paleontological resource inventory. All sensitive paleontological locality data has been redacted from this version of the report.
... In contrast to the record in the northern part of the United States and southern Canada, represented by well-preserved specimens, the hadrosaur record of New Mexico is comparatively sparse and taxonomically ambiguous despite over a century of collecting (Williamson, 2000). Also, limited in the San Juan Basin record, have been growth series and the presence of perinate, juvenile, and subadult individuals (Lucas et al., 2006;Robinson et al., 2015). ...
Article
An examination of specimens collected from the San Juan Basin in 1922 by Charles H. Sternberg has provided new evidence of the presence of hadrosaurid perinates in the region. The collection, housed at the Field Museum of Natural History, is composed of isolated elements from the Kirtland Formation of San Juan County, New Mexico. The perinatal individuals are represented by isolated elements including a scapula and femur, PR 1295. The smallest element, a scapula that is approximately 64 mm in length, is comparable in size to those of other hadrosaurid perinate individuals. The scapula is well preserved and lacks abrasion that would signify transport, suggesting that the perinatal elements were buried near their origin, potentially near a nesting site. These elements represent only the second known occurrence of perinatal hadrosaurids in the San Juan Basin.
Article
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The Coniacian-Santonian stages in western North America are characterized by a sparse fossil record. We present here the first account of dinosaur tracks from nine sites in the Frontier Formation (Coniacian-Santonian) of southwestern Montana. Tracks are largely preserved in distal alluvial facies as sandstone casts, with a single example of shallow epirelief impression interpreted as undertrack. Sandstone casts show significant relief, kinematic features (i.e., scale marks), and variable morphologies, arguing for a strong substrate control on their preservation. Putative producers are assigned to ornithopod, ankylosaurian, and theropod dinosaurs in decreasing order of abundance. This record reflects a composition similar to those of other middle Cretaceous formations in North America. Moreover, ankylosaurian tracks of the Frontier Formation represent the first known from Coniacian strata in North America. The incorporation of body and trace fossils yielded by the Frontier Formation indicates the presence of a fauna with North American endemic elements. The establishment of Coniacian-Santonian dinosaurian palaeocommunities akin to those observed in Campanian and Maastrichtian formations may reflect the trend towards provincialism attested for the end of the Mesozoic in North America.
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