A complete titanosaur femur from West Texas with comments regarding hindlimb posture

An isolated titanosaur femur recovered from the Javelina Formation (Maastrichtian) of Big Bend National Park, Texas is the most complete example yet reported from North America. The specimen is likely referable to Alamosaurus sanjuanensis, the only titanosaur thus far known from Upper Cretaceous strata in North America, but cannot be attributed with certainty to that taxon. Compared to femora from other titanosaurs, the specimen has a relatively reduced abductor crest, a less elevated femoral head, and a distal joint surface that is orthogonal to the long axis of the shaft. These differences suggest that the Big Bend femur pertains to a species where hindlimb stance was closer to vertical, and with a comparatively narrower gait than other titanosaurids.     

First pachycephalosaurid (Dinosauria: Ornithischia) from the Frenchman Formation (upper Maastrichtian) of Saskatchewan,Canada

Compared to earlier representatives of the family, pachycephalosaurids are less well known from upper Maastrichtian deposits around the world. Here, we report on a nearly complete left postorbital attributable to the pachycephalosaurid Sphaerotholus cf. Sphaerotholus buchholtzae from the upper Maastrichtian Frenchman Formation of Saskatchewan. This marks a probable northern range extension for the species into Canada, and the first occurrence of a pachycephalosaurid from this formation. We further demonstrate the taxonomic distinction between Stegoceras edmontonense and S. buchholtzae, which has been debated, based on postorbital sutural proportions. The northerly occurrence of Sphaerotholus cf. S. buchholtzae is consistent with the hypothesis of low beta diversity during the late Maastrichtian of North America, and its high stratigraphic incidence documents the persistence of non-pachycephalosaurin pachycephalosaurines in a critical interval for understanding the end-Cretaceous mass extinction event.     

Planktonic foraminifera and calcareous nannofossils record in the upper Campanian-Maastrichtian pelagic deposits of the Malatya Basin in the Hekimhan area (NW Malatya,eastern Anatolia)

The uppermost Cretaceous (upper Campanian-Maastrichtian) pelagic successions from the Malatya Basin (NW Malatya, eastern Anatolia) were studied by 688 samples, which were collected from five stratigraphic sections in the Hekimhan area. The pelagic deposits conformably overlie rudist bearing shallow-water limestones and are overlain conformably by Maastrichtian dolomites and unconformably by Paleocene-Eocene deposits, respectively.The pelagic successions in the Hekimhan area comprise the Kösehasan Formation at the base and the Zorbehan Formation at the top and reach up to 1100 m in thickness. The Kösehasan Formation rests over the neritic rudist-bearing limestones of the Güzelyurt Formation along a sharp contact and consists mainly of flysch-type sandstone-mudstone alternation with complete and partial Bouma sequences. The carbonate content of abundant planktonic foraminifera and nannoplankton-bearing 980-m-thick succession increases upwards and the formation passes gradually to the clayey limestones and marlstones of the Zorbehan Formation to the top. Occurrences of nannoplankton Lithraphidites quadratus Bramlette and Martini and Micula praemurus (Bukry) in the first beds of the Kösehasan Formation indicate that the age of the Kösehasan Formation and overlying Zorbehan Formation is of late Maasthrichtian. Another late Maastrichtian taxa Cribrosphaerella daniae Perch-Nielsen and Arkhangelskiella maastrichtiana Burnett are observed from the lowermost part of the succession. Maastrichtian planktonic foraminifera such as Contusotruncana walfischensis (Todd) and Globotruncanita pettersi (Gandolfi) were recorded through the successions. Although planktonic foraminifera are diverse and abundant particularly in the Kösehesan Formation, index late Maasthrichtian species were not encountered. Campanian and Santonian-Campanian planktonic foraminifera, e.g. Radotruncana calcarata (Cushman) and Globotruncanita elevata (Brotzen), obtained particularly from the lower part of the succession and calcareous nannofossils such as Broinsonia parca parca Bukry, Reinhardtites anthophorus (Deflanre) and Eiffellithus eximius (Stover) are interpreted as reworked from older strata. Trace fossils are common throughout the succession.Rareness of planktonic foraminifera and nannoplankton in the uppermost part of the succession (Zorbehan Formation) indicates maximum shallowing of the latest Maastrichtian sea in this part of the basin. Rare echinoids, bivalves and ammonites are observed in that part of the sequence.The obtained data indicate that sediment accumulation rate of the pelagic deposits is rather high and about 27.5 cm/ky for this part of the basin. Changes in thickness of the formations along short distances in the five stratigraphic sections analysed in this study should be related to the diachroneity of the depositional and erosional events.     

Dentaries of a caenagnathid (Dinosauria: Theropoda) from the Nemegt Formation of the Gobi Desert in Mongolia

A symphyseal region of the fused dentaries of a caenagnathid theropod is described from the Upper Cretaceous Nemegt Formation at the Bugin Tsav locality in the Mongolian Gobi Desert. In contrast to the high diversity of Caenagnathidae in the upper Campanian to Maastrichtian in North America, only specimens of a single caenagnathid, Elmisaurus raurus, have been reported in the coeval strata in Asia. Although dentaries are commonly-found bones in the fossil record of Caenagnathidae, the present specimen is the first discovery of caenagnathid dentaries from the upper Campanian to Maastrichtian in Asia. The Nemegt Formation is unique for its diverse oviraptorosaurian fauna that includes both Caenagnathidae and Oviraptoridae as well as the non-caenagnathoid Avimimus portentosus. Hypothesized coexistence of eolian and fluvial environments in the Gobi Basin during the deposition of the Nemegt Formation might explain such co-occurrence of Caenagnathidae and Oviraptoridae.     

Biostratigraphic and biogeographic implications of a hadrosaurid (Ornithopoda: Dinosauria) from the Upper Cretaceous Almond Formation of Wyoming,USA

The results of Barnum Brown's 1937 expedition to the Almond Formation of Wyoming consisted of two unidentified ceratopsian skulls and a partial hadrosaurid specimen (AMNH 3651). The hadrosaurid is here attributed to the Maastrichtian genus Saurolophus, verifying previous biostratigraphic correlations of this formation using ammonite zones. Fossiliferous lower Maastrichtian formations occurring latitudinally between those of Alberta, Canada, and southwestern Texas, USA, such as the Almond Formation, are essential for testing the effects and duration of apparent hadrosaurid faunal segregation earlier in the Campanian, and indirectly aiding in the placement of faunal boundaries that are currently unknown for the late Campanian. The discovery of Saurolophus in Wyoming, a close relative of the Campanian genus Prosaurolophus, affirms that the segregation of hadrosaurid faunas established in the late Campanian (～75 Ma) continued for at least 3 million years. Combining occurrences of Saurolophus from Mongolia and the Moreno Formation of California with those of Alberta, Canada, this genus appears to have had one of the largest geographic ranges of any equivalent clade of hadrosaurid dinosaur, although species level distributions are still uncertain.     

Planktonic foraminiferal biostratigraphy of the Coniacian-Maastrichtian sequences of the Bey Dağları Autochthon,western Taurides,Turkey: thin-section zonation

Planktonic foraminifer distributions in seventeen stratigraphic sections of Upper Cretaceous hemipelagic and pelagic sequences of northern Bey Da?lar? Autochthon (western Taurides) yield six biozones such as, Dicarinella concavata Interval Zone, Dicarinella asymetrica Range Zone, Radotruncana calcarata Range Zone, Globotruncana falsostuarti Partial Range Zone, Gansserina gansseri Interval Zone, and Abathomphalus mayaroensis Concurrent Range Zone. Two of the zones, Dicarinella concavata Zone and Dicarinella asymetrica Zone, are identified in the massive hemipelagic limestones of the Bey Da?lar? Formation, of Coniacian-Santonian age. They are characterized by scarce planktonic foraminifera and abundant calcisphaerulids. The other four biozones are determined from the cherty pelagic limestones of the Akda? Formation and indicate a late Campanian-late Maastrichtian time interval. The planktonic foraminifera observed in these four biozones are diverse, complex morphotypes (K-selection), suggesting open oceans. The assemblage of the Abathomphalus mayaroensis Zone shows that the latest Maastrichtian record is absent throughout the northern part of the autochthon. Two main sedimentary hiatuses are recognized within the Upper Cretaceous pelagic sequence. Early to middle Campanian and latest Maastrichtian-middle Paleocene planktonic foraminifera are absent in all measured stratigraphic sections. Hiatus durations differ between sections as a result of diachronism of onset of the hemipelagic and pelagic deposition and the post-Santonian and post-Maastrichtian erosional phases. Drowning event and the early-middle Campanian and latest Maastrichtian-middle Paleocene hiatuses in the pelagic sequence are attributed to regional tectonics during the Late Cretaceous.     

Reappraisal of Fresnosaurus drescheri (Plesiosauria; Elasmosauridae) from the Maastrichtian Moreno Formation,California, USA

The elasmosaurid Fresnosaurus drescheri, Welles from the contact between the Tierra Loma/Marca members of the Moreno Formation (Maastrichtian), California, USA is reviewed. Most of the features included in Welles's original diagnosis are considered related only to the juvenile ontogenetic stage of the holotype and only specimen. The new diagnosis is based on diagnostic characters of the ilia, including long rectangular shaped sacral facets located in the dorsal part of the shaft, two gentle knobs in the shafts and unexpanded dorsal end. Additional material from the Moreno Formation (numbered under the same number as the F. drescheri holotype but not mentioned by Welles and therefore considered part of a different specimen) are described for the first time. The latter are referred to the aristonectine, being the first evidence of aristonectines from the North Hemisphere.     

The Late Cretaceous Pterophyllum (Bennettitales) in the North-East of Russia

The Late Cretaceous Pterophyllum species survived as relict elements in areas influenced by volcanism in the North-East of Russia. Two new species are described: P. philippoviae Gnilovskaya from the Turonian-Coniacian deposits of the Vetvinskaya Unit (Penzhina and Oklan Rivers interfluve, Magadan Region) and P. terechoviae from the Maastrichtian deposits of the Kakanaut Formation (Kakanaut River Basin, Koryak Upland). The upper boundary of Pterophyllum stratigraphic range is extended from the Turonian-Coniacian up to the K/Pg boundary. Pterophyllum terechoviae is the youngest member of the genus and probably the latest occurrence of Bennettitales in the Northern Hemisphere.     

New material of the large-bodied caenagnathid Caenagnathus collinsi from the Dinosaur Park Formation of Alberta,Canada

A reexamination of large caenagnathid material from the Upper Cretaceous (Campanian) Dinosaur Park Formation of Alberta, Canada, reveals undescribed material referable to Caenagnathus collinsi. A femur, two astragalocalcanei, two metatarsals, two unguals, and a caudal vertebra provide anatomical information on Caenagnathus collinsi. Estimates of femoral length based on the proportions of other oviraptorids suggest that the non-femoral material represents a taxon intermediate in size between Chirostenotes pergracilis from the Dinosaur Park Formation and Anzu wyliei from the Maastrichtian Hell Creek Formation. The femur is within the range of predictions, and confirms the body size estimates based on the other material. The large size of the material and a number of morphological characters distinguish the material from Chirostenotes pergracilis and suggest that it is referable to Caenagnathus collinsi. The relative diversity of caenagnathids in the Dinosaur Park Formation is likely underestimated.     

A new species of Pluridens (Mosasauridae: Halisaurinae) from the upper Campanian of Southern Nigeria

The Upper Cretaceous of Africa has produced a diverse fauna of mosasaurs, including the highly specialized, long-jawed Pluridens. The type of Pluridens walkeri comes from the Maastrichtian Farin-Doutchi Formation of Niger, with a second, referred specimen coming from the Campanian section of the Campanian-Maastrichtian Nkporo Shale near Calabar, in southern Nigeria. Comparisons of this referred specimen with the holotype suggest that it represents a distinct and more primitive species. The Calabar jaw resembles P. walkeri in being long and narrow anteriorly with a shallow subdental shelf, and in having small, numerous, recurved teeth with medially positioned replacement pits. However, it lacks many of the derived features that characterize Pluridens walkeri, such as the extremely long and straight jaw, the extreme lateral protrusion and subcircular section of the dentary, strong transverse expansion of the dental thecae, and extreme reduction and increase in number of the teeth. The Calabar Pluridens is therefore referred to a new species, Pluridens calabaria. Following recent studies, Pluridens is considered to represent a highly derived member of the Halisaurinae. The marked differences between the Campanian and Maastrichtian species of the genus underscore the rapid pace of mosasaur evolution during the Cretaceous.     

The biostratigraphy of the uppermost calcareous nannofossils of Cretaceous deposit in both Shahdar and Namazgah sections (NE Iran)

A moderately various calcareous nannofossil assemblage of 44 species assigned to 24 genera is identified in samples collected from the Shahdar section and 18 genera and 43 species in Namazgah section. Testing of calcareous nannofossil has permitted recognition of few important coccolith events in stratigraphic interval occupied by the uppermost layers of Cretaceous in the Shahdar and Namazgah sections. These events are correlated to the CC24–CC26 of Sissingh (Geol Minjbouw 56: 37–65, 1977) in two sections. According to these biozones, the age of the studied sections in Shahdar and Namazgah is Early Maastrichtian–Late Maastrichtian. On the basis of paleoecological interpretation, the last layers related to the Cretaceous deposits in two sections were deposited in shallow marine environment in relatively low latitude, and the depth of the basin from the Cretaceous deposits toward Fajan Formation is minimized.     

A mosasaur,cf. Plotosaurus,from the upper Maastrichtian Quiriquina Formation in Central Chile

Here we describe a mosasaurid from the upper Maastrichtian Quiriquina Formation near the town of Cocholgüe about 30 km north of Concepción, central Chile. The specimen comprises a concretion preserving the rostral part of a pair of mandibular rami. The bulbous base of the teeth allows referral to cf. Plotosaurus sp. This is southernmost record of this piscivorous and pelagic taxon. The southern dispersal of mosasaurs during the late Maastrichtian may not only have depended from warm south-bound Equatorial currents but mainly from the nutrient-rich oceanic regime along an upwelling zone of cold abyssal water that mixed with the warm surface water, resulting in an enormous primary production. Apparently mosasaur dispersal depended more on food than on suitable temperatures or currents.     

Paleoecological implications of two closely associated egg types from the Upper Cretaceous St. Mary River Formation,Montana

Two closely associated egg types occur at the same locality in the Upper Cretaceous (Maastrichtian) St. Mary River Formation in north central Montana. These specimens represent the first fossil eggs described from this formation. At least fifteen small ovoid eggs or egg portions are scattered through a 25 cm interval of rock. Five significantly larger, round eggs overlie these smaller eggs and are in close proximity to one another on a single bedding plane. The best preserved egg of the smaller size measures 36 mm × 62 mm and exhibits the prismatic, two-layered eggshell structure of a theropod egg. The dispersed distribution and inconsistent angles of these small eggs likely resulted from disturbance by subsequent nesting activity and/or possibly nest predation. At least twelve additional small prismatic eggs also occur at this site. We assign the small eggs as a new oogenus and oospecies, Tetonoolithus nelsoni, within the Prismatoolithidae. The large round eggs measure 130 mm in diameter and the eggshell displays substantial diagenetic alteration. These eggs likely belonged to a hadrosaur due to their similarity in egg size, shape, and eggshell thickness to Maiasaura eggs from the stratigraphically lower Two Medicine Formation. Eggs at different stratigraphic levels at this site indicate that conditions favorable to both dinosaur species persisted for an extended period of time. However, determining whether these dinosaurs occupied the nesting site at the same or different years remains beyond the resolution of the rock record.     

New remains of Nothrotheriinae (Mammalia,Xenarthra) from Late Pleistocene fluvial deposits of Northern Pampa (Santa Fe Province,Argentina)

In this contribution the record of a Nothrotheriinae (Xenarthra, Tardigrada) ground sloth is reported from the Late Pleistocene of the Northern Pampa of Santa Fe Province, Argentina. The stratigraphic unit where the fossil was collected corresponds to fluvial-palustrine sediments of the Timbúes Formation, outcropping along the Carcarañá River valley. The relative stratigraphic position of this lithostratigraphic unit, observed in several sections mainly on the Paraná River cliffs near Carcarañá River distal area, suggests that it was deposited during the Last Interglacial Stage. The specimen (MPAHND-135), assigned to Nothrotherium cf. torresi, is represented by the proximal two-thirds of a left femur that shows a prominent lesser trochanter and no connection between the third trochanter and the ectepicondyle. The presence of Nothrotherium cf. torresi in sediments related to humid conditions supports the idea that Nothrotheriinae had great ecological tolerance and was capable of inhabiting climates ranging from cold and arid, as was previously proposed, to warm and humid.     

A neoselachian shark fauna from the Late Cretaceous of Senegal

A selachian fauna is described for the first time from the Late Cretaceous (Campanian–Maastrichtian) of Senegal. So far, the Campanian Paki Formation has only yielded a single tooth of Rhombodus sp. whereas the Cap de Naze Formation has yielded a more diverse fauna including juvenile Cretalamna cf. Cretalamna biauriculata, Serratolamna serrata, Carcharias cf. Carcharias heathi, ?Carcharias sp., Squalicorax pristodontus, Schizorhiza stromeri, Parapaleobates sp., Rhombodus binkhorsti and Rhombodus andriesi. Teeth of juvenile Cretalamna largely dominate the assemblage. Such an assemblage confirms a Late Maastrichtian age for the unit 3 in the Cap de Naze Formation. The assemblage, although composed of cosmopolitan taxa, is similar to the contemporaneous selachian assemblage from the phosphates of Morocco.     

A new specimen of Ichthyosaurus communis from Dorset,UK, and its bearing on the stratigraphical range of the species

This paper describes a new ichthyosaur specimen from the Stonebarrow Marls Member (Charmouth Mudstone Formation) of Charmouth, Dorset. It is substantially complete and various characters of the skull (snout ratios and basioccipital morphology) and appendicular skeleton (the number of digits on the hind paddle, which can be used to infer the number of digits on the front paddle) indicate that the specimen is referable to Ichthyosaurus communis. This provides the first direct evidence for the presence of I. communis in the Pliensbachian, extending the stratigraphic range of the species. The specimen also preserves a probable gullet content, which demonstrates that fish formed part of the diet of this individual.     

Late Cretaceous U–Pb tuff ages from the Skunk Ranch Formation and their implications for age of Laramide deformation,Little Hatchet Mountains,southwestern New Mexico,U.S.A.

LA-ICPMS U–Pb ages of individual zircon crystals from reworked ash-fall tuff beds in lacustrine strata of the Skunk Ranch Formation, a synorogenic unit deposited in a Laramide intermontane basin in the Little Hatchet Mountains, southwestern New Mexico, indicate an early Maastrichtian depositional age of 71–70 Ma. The dated beds are equivalent to nearby growth strata that are partially cut by, and folded over, a Laramide reverse fault. The strata thus record final displacement on the reverse fault and indicate an early Maastrichtian age for fault offset. The Skunk Ranch Formation was previously interpreted as Eocene in age and inferred to record the second event in a two-stage Laramide deformational history in the mountain range. In addition to significantly condensing the age range of the Laramide section and clarifying stratigraphic correlation in the Little Hatchet Mountains, the new ages of the formation also indicate that Laramide deformation in the range was likely restricted to a single Late Cretaceous episode.     

A gigantic caenagnathid oviraptorosaurian (Dinosauria: Theropoda) from the Upper Cretaceous of the Gobi Desert,Mongolia

A large, isolated symphyseal region of fused dentaries of an oviraptorosaurian was found in the Upper Cretaceous Bayn Shire Formation at Tsagaan Teg in the Mongolian Gobi Desert. A phylogenetic analysis places this specimen within Caenagnathidae. This specimen is comparable in size and morphology to the gigantic caenagnathid Gigantoraptor erlianensis from the Iren Dabasu Formation in China and is likely closely related to it. The occurrence of the specimen with possible affinities to G. erlianensis in the Bayn Shire Formation is consistent with the hypothesized correlation between the Bayn Shire and Iren Dabasu formations based on the co-occurrences of vertebrate fossils, especially turtles.     

Stratigraphy,sedimentology and tectonic evolution of the Upper Cretaceous/Paleogene succession in north Eastern Desert,Egypt

The stratigraphy, sedimentology and syn-depositional tectonic events (SdTEs) of the Upper Cretaceous/Paleogene (K–P) succession at four localities in north Eastern Desert (NED) of Egypt have been studied. These localities are distributed from south-southwest to north-northeast at Gebel Millaha, at North Wadi Qena, at Wadi El Dakhal, and at Saint Paul Monastery. Lithostratigraphically, four rock units have been recorded: Sudr Formation (Campanian–Maastrichtian); Dakhla Formation (Danian–Selandian); Tarawan Formation (Selandian–Thanetian) and Esna Formation (Thanetian–Ypresian). These rock units are not completely represented all over the study area because some of them are absent at certain sites and others have variable thicknesses. Biostratigrapgically, 18 planktonic foraminiferal zones have been recorded. These are in stratigraphic order: Globotruncana ventricosa Zone (Campanian); Gansserina gansseri, Contusotruncana contusa, Recimguembelina fructicosa, Pseudohastigerina hariaensis, Pseudohastigerina palpebra and Plummerita hantkenenoides zones (Maastrichtian); Praemurica incostans, Praemurica uncinata, Morozovella angulata and Praemurica carinata/Igorina albeari zones (Danian); Igorina albeari, Globanomanlina pseudomenradii/Parasubbotina variospira, Acarinina subsphaerica, Acarinina soldadoensis/Globanomanlina pseudomenardii and Morozovella velascoensis zones (Selandian/Thantian); and Acarinina sibaiyaensis, Pseudohastigerina wilcoxensis/Morozovella velascoensis zones (earliest Ypresian). Sedimentologically, four sedimentary facies belts forming southwest gently-dipping slope to basin transect have been detected. They include tidal flats, outer shelf, slumped continental slope and open marine hemipelagic facies. This transect can be subdivided into a stable basin plain plus outer shelf in the extreme southwestern parts; and an unstable slope shelf platform in the northeastern parts. The unstable slope shelf platform is characterized by open marine hemipelagic, fine-grained limestones and fine siliciclastic shales (Sudr, Dakhla, Tarawan and Esna formations). The northeastern parts are marked by little contents of planktonic foraminifera and dolomitized, slumped carbonates, intercalated with basinal facies. Tectonically, four remarkable syn-depositional tectonic events (SdTEs) controlled the evolution of the studied succession. These events took place strongly within the Campanian–Ypresian time interval and were still active till Late Eocene. These events took place at: the Santonian/Campanian (S/C) boundary; the Campanian/Maastrichtian (C/M) boundary; the Cretaceous/Paleogene (K/P) boundary; and the Middle Paleocene–Early Eocene interval. These tectonic events are four pronounced phases in the tectonic history of the Syrian Arc System (SAS), the collision of the Afro-Arabian and Eurasian plates as well as the closure of the Tethys Sea.     

Highly specialized suspension-feeding bony fish Rhinconichthys (Actinopterygii: Pachycormiformes) from the mid-Cretaceous of the United States,England, and Japan

We re-define the Cretaceous bony fish genus Rhinconichthys by re-describing the type species, R. taylori, and defining two new species; R. purgatorensis sp. nov. from the lowermost Carlile Shale (middle Turonian), southeastern Colorado, United States, and R. uyenoi sp. nov. from the Mikasa Formation (Cenomanian), Middle Yezo Group, Hokkaido, Japan. Rhinconichthys purgatoirensis sp. nov. is designated on a newly discovered specimen consisting of a nearly complete skull with pectoral elements. Only known previously by two Cenomanian age specimens from England and Japan, the North American specimen significantly extends the geographic and stratigraphic range of Rhinconichthys. The skull of Rhinconichthys is elongate, including an expansive gill basket, and estimated maximum body length ranges between 2.0 and 2.7 m. Rhinconichthys was likely an obligate suspension-feeder due to its derived cranial morphology, characterized by a remarkably large and elongate hyomandibula. The hyomandibula mechanically acts as a lever to thrust the jaw articulation and hyoid arch both ventrally and anterolaterally during protraction, thus creating a massive buccal space to maximize filtering of planktonic prey items. Cladistic analysis supports a monophyly of suspension-feeding pachycormids including Rhinconichthys, but further resolution within this clade will require more information through additional fossil specimens.