Medium 9780253008831

At the Top of the Grand Staircase: The Late Cretaceous of Southern Utah

Views: 697
Ratings: (0)

The Grand Staircase-Escalante National Monument in Utah is the location of one of the best-known terrestrial records for the late Cretaceous. A major effort in the new century has documented over 2,000 new vertebrate fossil sites, provided new radiometric dates, and identified five new genera of ceratopsids, two new species of hadrosaur, a probable new genus of hypsilophodontid, new pachycephalosaurs and ankylosaurs, several kinds of theropods (including a new genus of oviraptor and a new tyrannosaur), plus the most complete specimen of a Late Cretaceous therizinosaur ever collected from North America, and much more. At the Top of the Grand Staircase: The Late Cretaceous of Southern Utah documents this major stepping stone toward a synthesis of the ecology and evolution of the Late Cretaceous ecosystems of western North America.

List price: $72.99

Your Price: $58.39

You Save: 20%

Remix
Remove
 

28 Chapters

Format Buy Remix

1 One Hundred Thirty Years of Cretaceous Research in Southern Utah

ePub

Alan L. Titus

Southern Utah possesses a wild, stark, rugged landscape that leaves most people who experience it irrevocably and profoundly changed. Scenic wonders such as the Grand Canyon, Bryce Canyon (Fig. 1.1), Zion Canyon, The Wave, Buckskin Gulch, Cedar Breaks, and Capitol Reef are deservedly visited annually by millions of tourists from all over the globe who leave both awestruck and humbled. What is true for the tourist is even more so for the geologists and paleontologists who have worked in the canyon, mesa, plateau, and cliff outcrops of the Grand Staircase–Kaiparowits Plateau region ever since the first reports of the Powell expedition were published (e.g., Dutton, 1880; Howell, 1875). But the bedrock geology of the Grand Staircase provides not just the raw material for geomorphological agents to shape renowned scenic wonders; it also contains the fascinating saga of the evolving North American Cordilleran biosphere: a cavalcade of changing landscapes and organisms frozen in time for researchers to poke, prod, and ponder. Even though the area was first geologically mapped over 125 years ago, many basic stratigraphic and paleontological questions still remain unanswered. For vertebrate paleontologists, the region is still a frontier waiting to yield a wealth of data on the Mesozoic biosphere.

 

2 Geologic Overview

ePub

Alan L. Titus, Eric M. Roberts, and L. Barry Albright III

Cretaceous Strata in Southern Utah were Deposited in the proximal portion of the Sevier Foreland Basin. Total thickness of Cretaceous sediments probably exceeded 3000 m in the region before mid-Laramide uplift and erosion. Exposures are primarily found at the Kaiparowits Plateau and around the margins of the Markagunt and Paunsaugunt plateaus and the Pine Valley Mountain region. The Cretaceous section is divided up into the Cedar Mountain, Dakota, Tropic, Straight Cliffs, Wahweap, and Kaiparowits formations east of Parowan Canyon and is contained almost entirely within the Iron Springs Formation west. The sections are highly fossiliferous and yield one of the best records of Late Cretaceous terrestrial ecosystem evolution known in North America.

The state of Utah lies within both the Cordilleran Thrust Belt and Cordilleran Foreland Basin System (Fig. 2.1). The boundary between these two provinces, called the Cordilleran or Wasatch Hingeline (DeCelles, 2004), roughly parallels the east margin of the Sevier Fold and Thrust Belt. West of the Wasatch Hingeline are the extended and dissected remnants of thrust sheet stacks of Precambrian through early Mesozoic sedimentary rocks. East of the Wasatch Hingeline are thick sections of largely flat-lying Paleozoic, Mesozoic, and Paleogene sedimentary rocks (Hintze, 1988). Cretaceous strata crop out widely east of the Wasatch Hingeline, especially in the eastern Wasatch Plateau, Book Cliffs, Henry Basin, La Sal-Abajo Mountains, and the southern portion of the state (Fig. 2.2).

 

3 Accumulation of Organic Carbon-Rich Strata along the Western Margin and in the Center of the North American Western Interior Seaway during the Cenomanian-Turonian Transgression

ePub

Walter E. Dean, Erle G. Kauffman, and Michael A. Arthur

During the Cretaceous Period, The North American Western Interior Seaway occupied a rapidly subsiding north–south-trending basin that was characterized by substantial clastic sediment input derived from uplifted volcanic terranes of the Sevier orogenic belt to the west. At times of maximum transgression, the shoreline of the Western Interior Seaway extended as far west as western Utah and western Arizona, where thick deposits of fine-grained sediment rich in organic carbon (OC) were deposited. The Tropic Shale and correlative Tununk Shale Member of the Mancos Shale of southern Utah accumulated within a few hundred kilometers offshore from the western margin of the Western Interior Seaway; they record a part of the Greenhorn transgressive–regressive cycle that lasted about 4 Ma during which the Western Interior Seaway expanded to its maximum extent and then partially contracted. The entire thickness of the Tropic Shale was sampled in a 280-m-long core that was drilled and continuously cored at the base of the Kaiparowits Plateau near the town of Escalante, Utah (USGS #1 Escalante). The Tropic Shale, although called a shale, is more correctly a marlstone, containing up to 60% CaCO3, with an average of 34% in the Escalante core. Biostratigraphy and bentonite beds have allowed us to correlate peaks in concentration of CaCO3 with individual limestone beds in the Bridge Creek Limestone Member of the Greenhorn Formation in eastern Colorado and western Kansas. The Tropic Shale in the Escalante core is characterized by a generally upward increasing OC content, from a low value of <1% to a high value of 3%. The Cenomanian–Turonian (C/T) boundary is a time horizon marking a major oceanic anoxic event. It occurs about 20 m above the base of the Escalante core and is marked by a positive carbon isotope excursion, typical of the C/T oceanic anoxic event around the world. However, maximum accumulation of OC occurs much higher in the section, long after maximum Greenhorn transgression. Therefore, the Tropic Shale in the Escalante core apparently has recorded both global (oceanic anoxic event) and local events along the western shore of the Western Interior Seaway.

 

4 Tectonic and Sedimentary Controls, Age, and Correlation of the Upper Cretaceous Wahweap Formation, Southern Utah

ePub

Zubair Jinnah

The Wahweap Formation was Deposited by Fluvial to estuarine systems in the central part of the Western Interior Basin, between the Sevier fold-and-thrust belt to the west and the Western Interior Seaway to the east, during the Late Cretaceous. Today, the Wahweap Formation is exposed on the Markagunt, Paunsaugunt, and Kaiparowits plateaus in southern Utah. Equivalent rocks, assigned to the Masuk and Tarantula Mesa formations, also crop out in the Henry Mountains in south-central Utah. After the initial, preliminary description of the Wahweap Formation by Gregory and Moore (1931), little follow-up work had been conducted in the formation until two decades ago, when a renaissance of geologic and paleontologic investigations by multiple workers led to great improvements in understanding the vertebrate faunas, depositional environments, sequence stratigraphy, and depositional age of the formation. This chapter summarizes the geologic work performed in the Wahweap Formation and its seaward equivalent strata in the Henry Mountains to date, as well as presenting new data and interpretations on the sedimentology and regional lithostratigraphic, chronostratigraphic, and sequence stratigraphic correlations.

 

5 Implications of the Internal Plumbing of a Late Cretaceous Sand Volcano: Grand Staircase-Escalante National Monument, Utah

ePub

Edward L. Simpson, Hannah L. Hilbert-Wolf, Michael C. Wizevich, and Sarah E. Tindall

A Vertical, Cross-Sectional Exposure through a well-preserved sand blow and the associated volcano was discovered 1.8 m above the base of the Upper Cretaceous upper member of the Wahweap Formation. Preserved features within the feeder conduit (pipe) of the sand volcano facilitate reconstruction of the vertical fluid flow and interpretation of liquefied sand flow generated by local seismogenic faulting. In the lower reaches of the conduit, a dilation fracture crosscuts a low-permeability, fine-grained sandstone seal. Above this, the conduit widens and the edges become more diffuse in the overlying higher-permeability sandstone, and conversely, the pipe contracts in diameter as it passes through lower-permeability sandstones. This change in character of the pipe, in addition to the structureless sandstone adjacent to the pipe, indicates that lateral flow to the conduit was greater in the high-permeability zones. Within the pipe, subvertical stringers of granules 30 cm below the vent indicate that fluid flow of the liquefied sediment was of sufficient velocity to move granules. Medium to fine sand, elutriated from the sediment in the conduit, forms the subarial sand volcano cone. The internally massive surface volcano is slightly asymmetrical, measuring ~120 cm in apparent diameter and ~20 cm in height and is onlapped by the lee face of a fluvial dune.

 

6 The Kaiparowits Formation: A Remarkable Record of Late Cretaceous Terrestrial Environments, Ecosystems, and Evolution in Western North America

ePub

Eric M. Roberts, Scott D. Sampson, Alan L. Deino, Samuel A. Bowring, and Robert Buchwaldt

Updated Sedimentological and Paleontological data support earlier assertions that the Kaiparowits Formation was deposited in a wet alluvial to coastal plain setting with an abundance of large river channels and perennial ponds, lakes, and wetlands. A synthesis of available geochronological data from contemporaneous Upper Cretaceous continental sedimentary units was compiled, and many ages were recalibrated on the basis of new standards to provide the most up-to-date correlations of coeval strata and associated faunas across the Western Interior Basin. Recalibration of Kaiparowits Formation ash beds demonstrates that the formation is approximately half a million years older than previously suggested, deposited ~76.6–74.5 Ma. In addition, a new ash bed (bentonite) from the Horse Mountain area, collected in the lower portion of the middle unit of the Kaiparowits Formation (~190-m level), was radiometrically dated by both 40Ar/39Ar and U-Pb techniques, resulting in similar ages of 75.97 ± 0.18 Ma and 76.26 ± 0.05 Ma. Importantly, both ages are consistent with dated ash beds sitting above and below this level. Measured sections from throughout the outcrop expanse of the Kaiparowits Formation are correlated by an updated tephrostratigraphy, and key vertebrate fossil sites from throughout the formation are precisely tied into this stratigraphy. Updated geochronology and stratigraphy reveals that many of the most richly fossiliferous intervals across the Western Interior Basin are constrained to extremely narrow temporal intervals. The term taphozone was coined to describe broad geographic zones of exceptional and elevated continental fossil preservation within narrow temporal windows. Taphozones imply the existence of regional or basin-scale controls on fossil preservation. The Kaiparowits–Dinosaur Park–upper Two Medicine taphozone is assigned to the widespread interval of middle to late Campanian strata in the Western Interior Basin defined by the Kaiparowits, Dinosaur Park, and upper Two Medicine formations. Preliminary analysis of this phenomenon suggests that synchronous deposition of large volumes of volcanic ash across the basin during this time may be the primary driver of elevated fossil preservation in the Kaiparowits–Dinosaur Park–upper Two Medicine taphozone.

 

7 A Late Campanian Flora from the Kaiparowits Formation, Southern Utah, and a Brief Overview of the Widely Sampled but Little-Known Campanian Vegetation of the Western Interior of North America

ePub

Ian M. Miller, Kirk R. Johnson, Douglas E. Kline, †Douglas J. Nichols, and Richard S. Barclay

Fossil-Bearing Terrestrial Strata of Campanian age are widespread in the Western Interior Basin of North America and contain some of the world’s best known and most diverse dinosaurian faunas. More than 30 Campanian megafloras have been found from Texas to the Arctic, but our understanding of the vegetation they represent is poor because it is based on outdated 19th- and early 20th-century collections and studies. Nonetheless, these megafloral assemblages provide paleoclimate estimates that correlate with latitude and vegetation patterns that follow geographic barriers. Recent work on newly discovered sites since the early 1980s is largely unpublished or is focused on describing a few taxa or the nonangiosperm portion of the flora. We have discovered and extensively sampled 10 new megafloral sites from the upper Campanian Kaiparowits Formation (~76–74 Ma) in the exposure known as The Blues near Escalante, Utah. Results from a single, precisely dated (~75.69–75.72 Ma) site suggest that the flora of the Kaiparowits is exceptionally diverse (87 morphotypes) and dominated by angiosperms (62 dicot leaf morphotypes) that grew in a subtropical, megathermal, and relatively wet climate (mean annual temperature ~20°C and mean annual precipitation ~1.8 m). The palynoflora of the formation is correspondingly diverse and contains several paleoenvironmental indicators that suggest the formation was deposited in a slow-moving freshwater environment. Overall, the Kaiparowits flora has similarities to other Western Interior Campanian floras and some Maastrichtian floras; it hosts a diverse aquatic component mirroring the high abundance and diversity of aquatic vertebrate and invertebrate fossils in the formation. This element of the flora corroborates the sedimentological interpretation that the Kaiparowits Formation was deposited in a lowland floodplain with extensive ponding.

 

8 Continental Invertebrates and Trace Fossils from the Campanian Kaiparowits Formation, Utah

ePub

Leif Tapanila and Eric M. Roberts

A Survey of over 50 Localities for invertebrate fossils and their traces in the mudstones and sandstones of the Kaiparowits Formation, which spans 1.8 million years of Late Cretaceous (Campanian) time, demonstrates that it is one of the most prolific units in the Western Interior. Pulmonates, caenogastropods, and freshwater bivalves dominate the invertebrate fossil record both in number and diversity, and these are accompanied by ostracodes and a unique occurrence of bryozoan. Trace fossils such as the type specimens of Socialites nests and Osteocallis bone scrapings strongly suggest the activity of insects despite their absence in the body fossil record. At least 35 different aquatic and terrestrial gastropod and 13 freshwater bivalve morphotypes described from the formation support other independent evidence that the Campanian of southern Utah had a warm, humid climate with perennial aquatic environments. The highest-quality autochthonous preservation, including primary aragonite shell, occurs in facies interpreted as overbank ponds, lakes, and marshes. The greatest local diversity of 20 aquatic mollusk and one brackish-water bryozoan taxa is reported from a thick shell conglomerate that is interpreted as a mass-mortality storm deposit. Maximum diversity of mollusks in the middle of the formation appears to coincide with an increase in facies recording wetter fluvial environments, but future collecting efforts are required to isolate this relationship from taphonomic or sampling biases that may contribute to this preliminary signal.

 

9 Elasmobranchs from Upper Cretaceous Freshwater Facies in Southern Utah

ePub

James I. Kirkland, Jeffrey G. Eaton, and Donald B. Brinkman

Elasmobranch teeth from Freshwater facies are common in many microvertebrate assemblages in the Upper Cretaceous of western North America. Research on the essentially complete Upper Cretaceous terrestrial microvertebrate record of southern Utah has resulted in the collection of specimens from many stratigraphic horizons not sampled elsewhere. Two genera of hybodont shark and two clades of primitive (rhinobatoid and sclerorhynchoid) ray are present throughout the sequence. Orectoloboid sharks first appear in freshwater facies in the Coniacian, and two orectoloboid shark genera are present in the Campanian. Two new genera, Cristomylus and Pseudomyledaphus, are identified as part of a rapidly evolving line of myledaphine rhinobatoid rays; they include the new species Cristomylus nelsoni, Cristomylus bulldogensis, Cristomylus cifellii, and Pseudomyledaphus madseni. Additionally, the sclerorhynchoid sawfish Texatrygon brycensis and Columbusia deblieuxi and the orectoloboid shark Cantioscyllium markaguntensis are described.

 

10 Freshwater Osteichthyes from the Cenomanian to Late Campanian of Grand Staircase-Escalante National Monument, Utah

ePub

Donald B. Brinkman, Michael G. Newbrey, Andrew G. Neuman, and Jeffrey G. Eaton

Fossil Assemblages from the Grand Staircase Region of Utah provide data on patterns of diversity of bony fish from the Cenomanian through the late Campanian from the southern parts of the Western Interior of North America. Basal actinopterygians are prominent members of the assemblages and generally can be identified to at least family level. A high diversity of teleosts is also present, including hiodontiforms, osteoglossiforms, elopomorphs, clupeomorphs, ostariophysans, esocoids, and acanthomorphs, as well as taxa that cannot presently be placed in any lower-level taxonomic group. The small size of teleosts from the Late Cretaceous of the Grand Staircase region indicates that they would have occupied basal positions in the vertebrate food webs. A major faunal change occurred between the Cenomanian and Turonian assemblages, with a 47% change in taxa across the boundary. Amiids decrease in diversity, pycnodonts and Lepidotes become rare, and the Lepisosteidae, Vidalamiinae, and ostariophysan type U-3/BvD all first appear in the Turonian. A significant faunal turnover also occurred in the mid- to late Campanian, when esocoids and a characiform first appear. Turonian to middle Campanian assemblages show a successive appearance of five new taxa, including acanthomorphs, and a loss of two taxa. Latitudinal patterns are identified by comparing assemblages from the Kaiparowits Formation with contemporaneous assemblages from more northern localities. Lepisosteidae gen. et sp. indet. type 1 (the gar represented by lanceolate teeth), Lepidotes, Micropycnodon, Melvius, and ostariophysan type U-3/BvD have a more southern distribution, while sturgeon, holostean A, holostean B, Belonostomus and the teleosts Paratarpon, teleost indet. type H, the clupeomorph Horseshoeichthyes, and Coriops have a more northern distribution. Several of the biostratigraphic changes that are observed can be interpreted as shifts in the geographic distributions of these taxa that are associated with changes in mean annual temperatures during the Late Cretaceous.

 

11 Preliminary Report on Salamanders (Lissamphibia; Caudata) from the Late Cretaceous (Late Cenomanian-Late Campanian) of Southern Utah, U.S.A.

ePub

James D. Gardner, Jeffrey G. Eaton, and Richard L. Cifelli

Here we Report on Salamander Fossils (Vertebrae and jaws) and taxa identified from 19 microvertebrate localities of late Cenomanian–late Campanian age (an interval of about 25 million years) from the Dakota, Straight Cliffs, Iron Springs, Wahweap, and Kaiparowits formations in southwestern Utah, U.S.A. All three salamander families known from better-sampled upper Campanian–terminal Maastrichtian units elsewhere in the North American Western Interior are present in the Utah sequence: Scapherpetontidae and Batrachosauroididae occur throughout the late Cenomanian–late Campanian interval, whereas Sirenidae are limited to the Santonian–late Campanian. The scapherpetontid record consists of Scapherpeton (?Coniacian–late Campanian), Lisserpeton (late Campanian), and indeterminate older occurrences, including Lisserpeton-like vertebrae from the ?Coniacian and late Cenomanian, Piceoerpeton-like vertebrae from the ?Coniacian, and vertebrae of a probable new genus from the late Cenomanian. Batrachosauroidids are represented by Opisthotriton (Santonian–late Campanian), Prodesmodon (late Campanian), and a pair of indeterminate genera, one each from the late Turonian and late Cenomanian; the last occurrence is the oldest unequivocal record for batrachosauroidids in North America. The presence in pre-Santonian localities of scapherpetontid and batrachosauroidid specimens that cannot be assigned to known later Cretaceous and Paleogene genera indicates that both families were already present and diversifying by the early Late Cretaceous. The sirenid record is founded on Santonian–late Campanian atlantes of Habrosaurus; the Santonian occurrences are the oldest North American records for both the family and the genus. A previously unrecognized salamander of uncertain familial affinities (but showing some similarities to sirenids) is documented by distinctive trunk vertebrae and an atlantal centrum from the late Turonian–early or middle Campanian. Other enigmatic vertebrae likely pertaining to additional salamander taxa are reported from the late Cenomanian, late Turonian, and ?Coniacian. Most of the sampled localities contain multiple salamander genera and families; these diversities compare favorably with better sampled latest Cretaceous salamander assemblages elsewhere in the Western Interior, even though the compositions of those assemblages differ.

 

12 Anuran Ilia from the Upper Cretaceous of Utah–Diversity and Stratigraphic Patterns

ePub

Zbyněk Roček, James D. Gardner, Jeffrey G. Eaton, and Tomáš Přikryl

Thanks to their Relatively Robust Build and Distinctive structure, isolated ilia are among the most commonly recovered anuran bones from fossil micovertebrate sites. Across the spectrum of known anurans, there is considerable variation in features of the ilium. With some caveats, these features may be useful for assigning anuran ilia to biological taxa or, more conservatively, for estimating taxonomic diversities in fossil assemblages. A stratigraphically extensive sequence of 37 microvertebrate sites, ranging in age from the middle? Cenomanian–late Campanian (i.e., an interval of about 25 million years), in southwestern Utah, U.S.A., has yielded a relatively large sample of about 180 anuran ilia. Three major groups of ilia can be identified in the Utah sequence: those with an oblique groove on the medial surface, those with a dorsal tubercle, and those with neither structure. Within each group, specimens further can be subdivided into morphotypes based on other features (e.g., outline and relative size of acetabulum; extent and path of oblique groove; shape and position of dorsal tubercle). Some of the iliac morphotypes are discrete and easily recognizable, whereas others are less distinct. Certain of the iliac morphotypes (especially the more distinct ones) undoubtedly represent biological species, and the occurrence in many of the sampled localities and horizons of multiple morphotypes implies the presence in those areas of at least moderately diverse anuran assemblages. Only one iliac morphotype with an oblique groove can be assigned to a named genus, Scotiophryne, and this extends the temporal range for the genus back from the late Maastrichtian into the late Campanian. Although anuran ilia are not useful for stratigraphic correlations within the Utah sequence, several interesting patterns are evident; for example, the rarity both of specimens with a dorsal tubercle in the early–middle Santonian and middle Campanian and of specimens with an oblique groove in the late Santonian or early Campanian. The Utah ilia are typical for Mesozoic anurans in that none has a dorsal crest and only a minority have a dorsal tubercle; this contrasts with the situation in the Cenozoic, when most anurans have one or both of those iliac structures.

 

13 Turtles from the Kaiparowits Formation, Utah

ePub

J. Howard Hutchison, Michael J. Knell, and Donald B. Brinkman

Fossil turtle remains are Abundant in the Kaiparowits Formation and add to our understanding of turtle diversity, taxonomic relationships, and biogeography during the Late Cretaceous. A minimum of 14 taxa are present. Latitudinal patterns are identified by comparing the Kaiparowits assemblage with the contemporaneous assemblage from the Dinosaur Park Formation of Alberta. Non-trionychid taxa present in the Kaiparowits Formation but not in the Dinosaur Park Formation include Compsemys, Denazinemys nodosa, Plesiobaena sp. nov., a small smooth-shelled kinosternid, and the trionychids Helopanoplia and Derrisemys. These are considered members of a southern vertebrate assemblage. Taxa that are absent in the Kaiparowits Formation but present in more southerly localities are Hoplochelys and pleurodires. The absence of these taxa in the Kaiparowits Formation suggests that even further latitudinal subdivision of the turtle assemblages was present, and that the change from southern to northern assemblages is gradational. Several taxa that are restricted to southern localities in the late Campanian are present in the Late Maastrichtian Hell Creek of Montana. This change in distribution patterns is correlated with changes in climate.

 

14 Review of Late Cretaceous Mammalian Faunas of the Kaiparowits and Paunsaugunt Plateaus, Southwestern Utah

ePub

Jeffrey G. Eaton and Richard L. Cifelli

Mammals have been Recovered by wet Screen washing of microvertebrate localities in the Dakota Formation (Cenomanian); the Smoky Hollow (Turonian) and John Henry (Coniacian–Santonian) members of the Straight Cliffs Formation; the Wahweap Formation (lower–middle Campanian); and the Kaiparowits Formation (upper Campanian). The faunas of the Dakota Formation and the Smoky Hollow Member are unique to the North American record and are dominated by Paracimexomys-group multituberculates, archaic therian taxa, and metatherians. The fauna from the John Henry Member of the Straight Cliffs Formation is correlative with the fauna from the Milk River Formation (Aquilan), and its multituberculate fauna includes genera that are common later in the Cretaceous. The fauna from the Wahweap Formation includes taxa from the Paunsaugunt Plateau assigned previously to the Kaiparowits Formation. The fauna from the Wahweap Formation is not completely correlative with the Aquilan because it is younger. The first undoubted eutherians appear in this interval. The fauna from the Kaiparowits Formation is correlative with the Judithian but also exhibits noticeable endemism. Archaic taxa have disappeared, and there is a greater diversity of eutherians. Although there are differences between these faunas and more northerly assemblages, there are also marked faunal differences between the mammalian faunas of the Markagunt, Paunsaugunt, and Kaiparowits plateaus.

 

15 Late Cretaceous Mammals from Bryce Canyon National Park and Vicinity, Paunsaugunt Plateau, Southwestern Utah

ePub

Jeffrey G. Eaton

The Mammalian Fauna from the John Henry Member of the Straight Cliffs Formation (Santonian) of the Paunsaugunt Plateau described here includes an unidentified triconodont, cf. Alticonodon, Mesodma sp. cf. M. minor, Mesodma sp., ?Mesodma sp., Cimolodon sp. cf. C. foxi, Cimolodon similis, Cimolodon sp. cf. C. similis, ?Cimolodon sp., Cimolomys sp. A, Cimolomys sp. B, ?Cimolomys sp. A, ?Cimolomys sp. B, Dakotamys sp., D. shakespeari sp. nov., Cedaromys sp. cf. C. hutchisoni, ?Spalacotheridium sp., Symmetrodontoides sp., an unidentified didelphid, Apistodon sp. cf. A. exiguus, cf. “Anchistodelphys” sp., ?Varalphadon sp., Eodelphis sp., an unidentified pediomyid, and ?Leptalestes sp. The fauna from the Wahweap Formation (Campanian) of the Paunsaugunt Plateau described here includes ?Paracimexomys sp., Cedaromys sp. cf. C. hutchisoni, Mesodma sp. cf. M. minor, M. sp. cf. M. archibaldi, M. sp. cf. M. formosa, Cimolodon sp. cf. C. foxi, Cimolomys sp., ?Cimolomys sp., Meniscoessus sp., cf. Iugomortiferum sp., unidentified didelphids sp. A and B., cf. Apistodon sp., Varalphadon sp. cf. V. creber, cf. Varalphadon sp., and an unidentified pediomyid. The fauna of the Wahweap Formation from the Paunsaugunt Plateau compares well to the fauna from the Wahweap Formation on the Kaiparowits Plateau, but also compares well to the fauna recovered from the underlying John Henry Member. However, the fauna does not compare closely to that recovered from the Kaiparowits Formation. This is unexpected because the Wahweap fauna should be essentially middle Campanian and the Kaiparowits faunas early Late Campanian, as based on radiometric dates, and a substantial unconformity (the Early Campanian) should separate the Wahweap Formation from the Santonian John Henry Member if these dates are correct. The fauna from the Wahweap Formation also correlates well with that of a locality 200 m below the top of the Cretaceous on the Markagunt Plateau suggesting that locality may also be Campanian in age. Neither fauna compares well to that recovered from the highest known fauna from the Cretaceous sequence on the Markagunt Plateau.

 

16 Lizards and Snakes from the Cenomanian through Campanian of Southern Utah: Filling the Gap in the Fossil Record of Squamata from the Late Cretaceous of the Western Interior of North America

ePub

Randall L. Nydam

A Rich and Diverse Fauna of Lizards and Snakes has been recovered from the Cenomanian–Campanian of southern Utah. The specimens reported herein represent eight new taxa, 19 named taxa, and 34 distinct, unnamed morphotypes from the Dakota Formation (Cenomanian), Smoky Hollow Member of the Straight Cliffs Formation (Turonian), Iron Springs Formation (Cenomanian–Santonian), John Henry Member of the Straight Cliffs Formation (Coniacian), Wahweap Formation (Santonian–early Campanian), and Kaiparowits Formation (mid-Campanian). Although each fauna is taxonomically and morphologically distinct (although only a very few taxa are currently known from the Iron Springs and Wahweap formations), most of them share the presence of Chamopsiidae, Polyglyphanodontinae, Contogeniidae, cf. Xenosauridae, Platynota, and Serpentes. Additionally, many taxa and/or unnamed morphotypes from the reported faunas are referable to Paramacellodidae, a taxon with its origins in the Jurassic. The presence of jaws referable to two distinct species of Odaxosaurus in the Kaiparowits Formation represents the first record of two co-occurring species of Odaxosaurus in the Western Interior and the earliest conclusive evidence of anguids in southern Utah, although anguid-grade osteoderms are known from as early as the Cenomanian. The overall composition of the described faunas represents a very consistent taxonomic/morphologic diversity with the greatest change being a substantial increase in chamopsiid and platynotan diversity by the mid-Campanian. Only a small sample of squamate specimens has been recovered from the Santonian–early Campanian, and additional investigation of these horizons is still necessary.

 

17 Crocodyliforms from the Late Cretaceous of Grand Staircase-Escalante National Monument and Vicinity, Southern Utah, U.S.A.

ePub

Randall B. Irmis, J. Howard Hutchison, Joseph J. W. Sertich, and Alan L. Titus

Although the Kaiparowits Basin of Southern Utah contains an excellent Late Cretaceous stratigraphic record of nonmarine fossiliferous sediments, crocodyliforms from these deposits remain poorly known. Isolated teeth and osteoderms from the Dakota and Straight Cliffs formations document the presence of widespread large clades such as Mesoeucrocodylia and Neosuchia, but finer taxonomic resolution is not currently possible. The record from the middle Campanian Wahweap Formation is similarly fragmentary but also includes specimens assignable to Crocodylia, the crown group of crocodyliforms. By far the best-known crocodyliform assemblage from the Late Cretaceous of Utah is that of the late Campanian Kaiparowits Formation, which preserves the remains of at least three alligatoroids: Deinosuchus hatcheri, Brachychampsa, and an unnamed small alligatoroid that lacks globidont teeth. The Wahweap and Kaiparowits formations also preserve large rectangular osteoderms of an indeterminate basal neosuchian that might be related to the goniopholidid Denazinosuchus from the late Campanian of the San Juan Basin in northern New Mexico but could also pertain to a late surviving pholidosaurid. The Kaiparowits Formation crocodyliform assemblage is most similar to that of the Fruitland and Kirtland formations in the San Juan Basin, and differs from more northerly assemblages in Montana and Alberta. Kaiparowits crocodyliforms provide additional evidence for a distinct southern Laramidian vertebrate faunal province during the Campanian and possible climate-induced northern migration of southern taxa during the Maastrichtian.

 

18 Review of Late Cretaceous Ankylosaurian Dinosaurs from the Grand Staircase Region, Southern Utah

ePub

Mark A. Loewen, Michael E. Burns, Michael A. Getty, James I. Kirkland, and Matthew K. Vickaryous

New Ankylosaur Specimens from Grand Staircase–Escalante National Monument, Utah, provide data on the distribution and diversity of ankylosaurian dinosaurs of southern Laramidia. These materials are from the Dakota, Straight Cliffs, Wahweap, Kaiparowits, and laterally equivalent formations of the Grand Staircase of southern Utah. The earliest record of ankylosaurs from Grand Staircase–Escalante National Monument is based on a tooth from the Dakota Formation. Teeth and postcranial elements of both nodosaurids and ankylosaurids are present in the Straight Cliffs and Wahweap formations, and their lateral equivalents. Specimens from the Kaiparowits Formation include nodosaurid teeth and a distal cervical spine, and several ankylosaurid specimens represented by teeth, cranial fragments, postcrania, osteoderms, and tail clubs.

Analysis of the ankylosaurid material from the Kaiparowits Formation indicates that there are two distinct, essentially coeval, ankylosaurids from the lower middle unit of the Kaiparowits Formation.

 

Load more


Details

Print Book
E-Books
Chapters

Format name
ePub
Encrypted
No
Sku
B000000031676
Isbn
9780253008961
File size
27.6 MB
Printing
Allowed
Copying
Allowed
Read aloud
Allowed
Format name
ePub
Encrypted
No
Printing
Allowed
Copying
Allowed
Read aloud
Allowed
Sku
In metadata
Isbn
In metadata
File size
In metadata