Anaerobic and Aerobic Oxidation of Methane at Late Cretaceous Seeps in the Western Interior Seaway,USA

The Late Cretaceous (Campanian) Tepee Buttes represent a series of conical, fossiliferous limestone deposits embedded in marine shales that deposited in the Western Interior Seaway. The previously suggested origin of the Tepee Buttes at methane-seeps was confirmed by this study. δ¹³C values as low as ?50‰ of early diagenetic carbonate phases of two Tepee Buttes near Pueblo (Colorado) reveal that methane was the major carbon source. Molecular fossils released from a methane-seep limestone contain abundant ¹³C-depleted archaeal lipids (PMI, biphytane; δ ¹³C: ?118 and ?102‰), derived from anaerobic methanotrophs. A suite of ¹³C-depleted bacterial biomarkers (branched fatty acids; ?73 to ?51‰) reflects the former presence of sulfate-reducing bacteria, corroborating that a syntrophic consortium of archaea and bacteria mediating anaerobic oxidation of methane already existed in Cretaceous times. Molecular fossils also suggest that methane was not exclusively oxidized in an anaerobic process. A series of unusual C₃₄/C₃₅-8,14-secohexahydrobenzohopanes with low δ¹³C values (?110 and ?107‰) points to the presence of aerobic methanotrophic bacteria at the ancient seep site.     

Evolutionary stasis,ecophenotypy and environmental controls on ammonite morphology in the Late Cretaceous (Maastrichtian) Western Interior Seaway,USA

We test for the presence of evolutionary stasis in a species of Late Cretaceous ammonoid cephalopod, Hoploscaphites nicolletii, from the North American Western Interior Seaway. A comprehensive dataset of morphological traits was compiled across the entire spatial and temporal range of this species. These were analysed in conjunction with sedimentologically and geochemically derived palaeoenvironmental conditions hypothesized to apply selective pressures. All changes in shell shape were observed to be ephemeral and reversable, that is, no unidirectional trend could be observed in any of the morphological traits analysed. Correlations between palaeoenvironmental conditions and morphological traits suggests ecophenotypic processes were at play; however, either environmental changes were too minor and/or provided no isolating mechanism to drive speciation. These data support mechanisms of stasis such as homogenizing gene flow or stabilizing selection under a fluctuating optimum (probably reflecting spatiotemporally heterogeneous palaeoenvironmental conditions). Finally, changes in shell size were not significantly associated with changes in shell-specific δ¹⁸O, despite a correlation between shell size and δ¹⁸O averaged across horizons. This suggests a mismatch in scales of geochemical sampling that supports caution when making broad interpretations based on averaged geochemical data.     

Dinosaur Tracks from the Kilmaluag Formation (Bathonian,Middle Jurassic) of Score Bay,Isle of Skye,Scotland, UK

Tracks of a juvenile theropod dinosaur with footprint lengths of between 2 and 9 cm as well as adults of the same ichnospecies with footprints of about 15–25 cm in length were found in the Bathonian (Middle Jurassic) Kilmaluag Formation of Score Bay, northwestern Trotternish Peninsula, Isle of Skye, Scotland, UK. Two footprint sizes occur together on the same bedding plane in the central portion of Score Bay, both in situ and on loose blocks. Another horizon containing footprints above this was also identified. The footprints from the lowest horizon were produced in a desiccated silty mud that was covered with sand. A close association of both adults and juveniles with similar travel direction indicated by the footprints may suggest post-hatching care in theropod dinosaurs. Other footprints, produced on a rippled sandy substrate, have been found on the slightly higher bedding plane at this locality. Loose blocks found 130 m to the northeast in the central part of Score Bay have not been correlated with any in situ sediments, but were preserved in a similar manner to those from the higher bedding plane. These tracks represent the youngest dinosaur remains yet found in Scotland.     

Cycadeoidea marylandica (Bennettitales) from the late Albian of Spain and its palaeophytogeographical implications

The first evidence of the presence of Cycadeoidea marylandica (Order Bennettitales) in the Cretaceous of Eurasia is presented. The single specimen consists of a trunk fragment found in the late Albian deposits of the Utrillas Formation, near the village of Gargallo (NE Spain). It is a cylindrical fragment of a silicified trunk with exceptional preservation of external structures (leaf scars and cones). The characteristics of the cones indicate different states of development. The presence of this taxon in deposits of southwestern Eurasia further supports the hypothesis that floristic exchange occurred between North America and the islands that composed the Iberian Plate during Albian times.     

Ephedroid fossil pollen from the Lower Cretaceous (Upper Albian) of Hokkaido,Japan

This paper presents eight ephedroid palynomorphs from the Lower Cretaceous (Upper Albian) of Hokkaido, Japan. The ephedroid palynomorphs are ellipsoid and polyplicate pollen grains that show a wide range of variation in pollen size, shape, and plication. These ephedroid palynomorphs suggest a wide range of diversity in Gnetales at mid- or high-paleolatitude in the eastern side of Lauresia during the Upper Albian.     

Extramorphological Features of Sauropod Dinosaur Tracks in the Uhangri Formation (Cretaceous), Korea

Sauropod footprints in the Uhangri Formation (Cretaceous) of Korea exhibit an unusual pattern of morphology, with the interior of each print partitioned into a series of pockets by conspicuous radial crests. The crests are evidently extramorphological features and have been interpreted as upwellings of sediment extruded through the floor of the footprint following its fracture by impact of the trackmaker's foot. That explanation entails some inconsistencies, and an alternative explanation is proposed here. The alternative explanation envisages delamination of a superficial sheet of sediment that was lifted into a canopy, which subsequently collapsed in radiating folds. The superficial sheet of sediment might have been lifted by either or both of two mechanisms—by adhering to the underside of the trackmaker's foot or by being forced upward into a blister-like dome by the backflow of water previously displaced by impact of the trackmaker's foot. These alternative explanations draw attention to minor morphological features that were previously unexplained.     

Late Cretaceous (Cenomanian to Campanian) paleoenvironmental history of the Eastern Canadian margin of the Western Interior Seaway: bonebeds and anoxic events

Upper Cretaceous strata in the Pasquia Hills of the northern Manitoba Escarpment, eastern Saskatchewan, Canada provide a detailed paleoenvironmental and sea-level record of the eastern margin of the Western Interior Seaway. Sediments deposited during the Cenomanian/Turonian Greenhorn marine cycle are dominantly black mudstones deposited in a stratified water column, with bottom-water anoxia recurrently reaching into the photic zone. A middle Cenomanian sea-level lowstand event followed by transgression left a series of bonebeds within the Belle Fourche Member of the Ashville Formation, indicating a sedimentary environment starved of coarse siliciclastics. Maximum sea level resulted in the formation of limestone beds within the Favel Formation, further favoured by reduced terrigenous sediment input compared to the western margin. Limestone sedimentation was followed by a phase of increased freshwater input under lower sea level conditions, and reducing zoo- and phytoplankton diversities. During final Greenhorn regression, eastern Saskatchewan probably turned into a restricted basin severely limiting marine circulation. Poor or absent benthic foraminiferal assemblages and biomarker analysis suggest prevailing watermass stratification throughout the Cenomanian/Turonian transgressive/regressive cycle. This was caused either by a freshwater lid, stratification of Boreal and Tethyan-derived watermasses, or both, to various intensities affected by changing sea level. Basin oxygenation during Niobrara time varies between localities along the eastern margin as documented by presence/absence of benthic and planktic foraminifera.     

Paleoceanography of the Late Cretaceous (Maastrichtian) Western Interior Seaway of North America: evidence from Sr and O isotopes

Well-preserved fossils of the Late Cretaceous Western Interior Seaway (WIS) of North America have been analyzed for Sr concentration and Sr and O isotopes in order to decipher paleosalinities and paleotemperatures. The samples are from four biofacies within the Seaway (late Maastrichtian): offshore Interior (Pierre Shale), nearshore Interior (Fox Hills Formation), brackish (reduced salinity; Fox Hills Formation) and freshwater (Hell Creek Formation). Samples were also obtained from the Severn Formation of Maryland (considered to be representative of the open ocean). All biofacies (except the freshwater) are demonstrably within the Jeletzkytes nebrascensis ammonite zone (<1 Ma duration). The ⁸⁷Sr/⁸⁶Sr ratios show significant and systematic decreases from marine (mean±1 S.D.=0.707839±0.000024) to brackish facies (mean±1 S.D.=0.707677±0.000036), consistent with dilution by freshwater with a lower ⁸⁷Sr/⁸⁶Sr ratio than seawater. Such variation disallows using the ⁸⁷Sr/⁸⁶Sr ratios of fossil shell material to assign ages to fossils from the Late Cretaceous WIS without knowledge of the salinity in which the organism grew. The Sr isotope ratios for scaphitid ammonites within a single biofacies are similar to each other and different from those for scaphites in other biofacies, implying that these organisms are restricted in their distribution during life. The ⁸⁷Sr/⁸⁶Sr values of freshwater unionid mussels range widely and are not compatible with the freshwater endmember ⁸⁷Sr/⁸⁶Sr ratio required by the trend in ⁸⁷Sr/⁸⁶Sr vs. biofacies established from the other samples. Paleosalinities for the biofacies are estimated to range from 35‰ in the open marine to a minimum of 20‰ in the brackish, based on the presence of cephalopods in all four facies and the known salinity tolerance of modern cephalopods. Producing reasonable ⁸⁷Sr/⁸⁶Sr values for the freshwater endmember of a ⁸⁷Sr/⁸⁶Sr vs. 1/[Sr] plot requires a Sr concentration 0.2-0.5 that of seawater for the dominant freshwater input to the WIS. Such high Sr concentrations (relative to seawater) are not observed in modern rivers, and we suggest that the brackish environment in the WIS arose through the mixing of freshwater and seawater in a nearshore aquifer system. Reactions of the solution with aquifer solids in this ‘subterranean estuary’ [Moore, Mar. Chem. 65 (1999) 111-125] produced brackish water with the Sr concentration and isotopic composition recorded in the brackish biofacies. δ¹⁸O values of the fossils show decreases from the marine to brackish biofacies consistent with increasing temperatures (from ∼13 to 23°C) or, if temperatures were relatively constant, to a decrease in the δ¹⁸O of the water in which the shell formed. The latter interpretation is consistent with less-than-fully marine salinities in the nearshore biofacies, but both changes in temperature and the isotopic composition of the water may have occurred in this environment.     

New reconstruction of Weichselia reticulata (Stokes et Webb) Fontaine in Ward emend. Alvin, 1971 based on fertile remains from the middle Albian of Spain

Exceptionally well-preserved specimens from the middle Albian of Spain corresponding to a nearly complete fertile frond and fragments of pinnae containing soral clusters of the tree fern Weichselia reticulata have provided new data about the structure and arrangement of pinnae and their associated fertile reproductive structure. This new material has been compared with the previous studies, and recostructions of this fern and the new data indicate the segregation of vegetative and fertile fronds within the main stipe of this fern.     

Predation of late Marjuman (Cambrian) linguliformean brachiopods from the Deadwood Formation of South Dakota, USA

One hundred and twenty-five linguliformean brachiopods of late Marjuman (Cambrian) age with shell perforations, presumably caused by predation, were recovered from shallow-water limestones at two localities of the Deadwood Formation in the Black Hills of South Dakota, USA. Three-quarters of the perforated valves belonged to taxa in the order Acrotretida, while one-quarter of the specimens belonged to those of the order Lingulida. This is the first report of predation of fossil lingulids. In both orders there was a marked selection for valve type. Ninety-five per cent of all perforations of acrotretids were in the ventral valve, while 87% of all perforations of lingulids were in the dorsal valve. The highest rate of predation of collected acrotretids, at any stratigraphic horizon, was 22%, while the rate of predation of collected lingulids, at any given stratigraphic horizon, was as high as 9%. Half of the perforated valves had round holes with a sharp, non-beveled exterior edge, and half had irregularly shaped holes with chipped interior edges. The former type is attributed to either boring or a swift, piercing percussive strike, while the latter is attributed to a smashing percussive strike with a blunt appendage. A third type of perforation consisting of minute, roughly circular holes is thought to be too small to be the work of predators, and is assumed to be the result of an encrusting organism or parasite. The different types of perforation seen in the brachiopod valves indicate that there was more than one type of predator attacking them, including possibly one of the earliest durophages. Various hypothetical predators are suggested as potential candidates for causing the shell perforations. The criteria for their selection as possible linguliformean predators include possessing the ability to produce one of the two types of shell perforation, and being small enough to warrant preying on small (< 2 mm) brachiopods.     

The regional record of Albian oceanic anoxic events at the Apulian Platform Margin (Gargano Promontory, southern Italy)

The Gargano Promontory, located on the eastern margin of the Apulia Platform, represents a distinctive Tethyan area where the transition from carbonate platform to adjacent basin is exposed on land. The Albian stratigraphic record, represented by shallow-water, slope and deep-water deposits, provides a good opportunity to investigate the regional response to oceanic anoxic events (OAEs) in different depositional settings by using an integrated, high-resolution micropalaeontological (planktonic foraminifers and calcareous nannofossils) approach. Results show that organic matter preservation is confined to the more distal areas (Marne a Fucoidi Formation), and consists of black shale intervals from the middle and late Albian (Ticinella primula/Prediscosphaera columnata Zones; upper Ticinella praeticinensis Subzone/R. achlyostaurion Zone, respectively). Integrated biostratigraphic data correlate the intervals of black shale deposition to the Urbino and Amadeus levels, previously identified and named in the Umbria-Marche Basin. These black shales record the effects of OAEs 1b and 1c. The biotic changes in the pelagic Albian succession of the Apulian Platform Margin provide evidence for episodes of eutrophication that correlate to the deposition of these black shales. Genetic models for the two episodes of organic matter preservation are proposed, taking into account both global and local controlling factors.     

Dinosaur Tracks from the Cedar Mountain Formation (Lower Cretaceous), Arches National Park,Utah

The seventh and largest known dinosaur tracksite from the Cedar Mountain Formation is reported from two important stratigraphic levels in the Ruby Ranch Member within the boundaries of Arches National Park. Previous reports of sites with a few isolated tracks are of limited utility in indicating the fauna represented by track makers. The Arches site reveals evidence of several theropod morphotypes, including a possible match for the coelurosaur Nedcolbertia and an apparently didactyl Utahraptor-like dromeosaurid. Sauropod tracks indicate a wide-gauge morphotype (cf. Brontopodus). Ornithischian tracks suggest the presence of an iguandontid-like ornithopod and a large ankylosaur. Dinosaur track diversity is high in comparison with other early Cretaceous vertebrate ichnofaunas, and it correlates well with faunal lists derived from skeletal remains, thus providing a convincing census of the known fauna.     

Durophagous predation on scaphitid ammonoids in the Late Cretaceous Western Interior Seaway of North America

This study is the first to report a trend of predation intensity on scaphitid ammonoids from the Turonian to the Maastrichtian (Late Cretaceous) on the basis of analysis of ventral shell breakage in large samples from the US Western Interior Province. Analysis of 835 adult specimens revealed ventral shell breakage in 50 specimens. In most of the damaged specimens, the breakage occurred in a preferred position at the rear part of the body chamber. Ventral breakage is rare in the Turonian specimens, whereas it is common in the Campanian and Maastrichtian specimens. The shell diameter of adult scaphitid ammonoids tends to increase with time. The position of the breakage and the absence of repairs indicate that the ventral breakage resulted from lethal predation. Based on the incidence of breakage and the size and shape of the breaks, possible predators include fish, reptiles and cephalopods such as Placenticeras, Eutrephoceras and coleoids. Our statistical analysis of ventral shell breakage indicates that the incidence of lethal predation increased in conjunction with an increase in adult shell size, suggesting that the body size of the prey was an important factor in predator–prey interactions. In addition, the predatory damage is more extensive in larger adults.     

Angiosperm pollen grains of San Just site (Escucha Formation) from the Albian of the Iberian Range (north-eastern Spain)

The most complete angiospermous palynological assemblage for the middle-earliest late Albian of north-eastern Spain is reported from the Middle Member of the Escucha Formation at the San Just site. Nine palynological samples yielded mainly monosulcates (Clavatipollenites, Dichastopollenites, Hammenia, Jusinghipollis, Liliacidites, Pennipollis including proposed new species P. escuchensis, Retimonocolpites, and Transitoripollis) and a few tricolpates (Phimopollenites, Rousea, Striatopollis, and Tricolpites). These assemblages, mainly composed of angiosperm pollen grains, suggest that significantly diversified flowering plants flourished both in brackish and freshwater swamp plain environments represented by the Escucha Formation in Albian times, although they were less diverse than angiosperms in the Late Cretaceous. The palynological assemblages share greatest similarities with those of other southern Laurasian localities, although there are some taxa more typical of palynofloras of northern Gondwana.     

Fossil amoebae (Hemiarcherellidae fam. nov.) from Albian (Cretaceous) amber of France

Abstract: Two extraordinarily well‐preserved testate amoebae are described from Late Albian age amber from south‐western France. The specimens are attributed to a new family, the Hemiarcherellidae fam. nov., and are described as Hemiarcherella christellae gen. et sp. nov. The amoebae described herein originate from highly fossiliferous amber pieces. Based on syninclusions, Hemiarcherella christellae was a soil‐dwelling organism, probably an active bacterivore. This taxon represents the third species of testate amoebae described from mid‐Cretaceous French amber. Analysis of this fossil amoeba fauna illustrates the uniqueness of mid‐Cretaceous French amber deposits. Indeed, most amoebae found in amber have been assigned to modern species, corroborating the hypothesis of morphological stasis in different microbial lineages. However, the well‐preserved amoebae fauna found in French amber can be distinguished clearly from modern species and help us to better understand the fossil record of these organisms.     

Echinoderm faunas from the Lower Cretaceous (Aptian–Albian) of Alexander Island,Antarctica

Abstract: Strata assigned to the Fossil Bluff Group on Alexander Island, Antarctica, contain Aptian to Albian high‐latitude echinoderm faunas that lived at palaeolatitudes greater than 60 degrees south. The Pluto Glacier Formation, of essentially Aptian age, yields a deep‐water assemblage that includes two ophiuroids, an ophiacanthid and a representative of the ophiolepidid genus Mesophiomusium, both represented by partially articulated specimens. The echinoid fauna includes a new genus of diadematoid, Australidiadema, and a new genus of disasteroid, Notidisaster, which extend the record of both groups into the southern hemisphere. The overlying Neptune Glacier Formation, of late Albian age, yields only spatangoids which are common but rarely well enough preserved to be identified even to genus level, although at least some belong to the genus Hemiaster.     

Reappraisal of the latest Albian (Mortoniceras fallax Zone) cephalopod fauna from the classical Salazac locality (Gard,southeastern France)

The Salazac locality (Gard, southeastern France) is renowned for the richness of its cephalopod fauna (especially ammonites) from the Mortoniceras fallax Zone (uppermost Albian, Lower Cretaceous). However, most ammonite species have paradoxically been scarcely illustrated up to now. Furthermore, the rare assessments of ammonite taxonomic diversity are presumably inaccurate, as they either result from a drastic typological approach or could not benefit from the most recent advances in modern concepts of ammonoid intraspecific and ontogenetic variations. In this work, we document an original cephalopod assemblage from Salazac represented by abundant, well-preserved specimens (564 studied ammonites, including ca. 50% of heteromorphs) constituting a high diversity. The sample size and quality of this new material allowed some extensive morphological and biometric analyses whenever possible (i.e., for subdatasets in which a significant number of measurements is available) and to thoroughly assess intraspecific and ontogenetic variations for a few species. This led to determine the diagnostic value of various shell characters commonly used to characterize both well-documented and poorly-defined species. In particular, we show that a significant part of the variation in the number of ribs per whorl within the heteromorphic genera Mariella and Turrilitoides is directly related to shell size and that the strength of tubercles covaries negatively with the number of ribs in Mariella, therefore challenging the diagnostic value of these characters. We further suggest that rib density covaries with whorl shape in Mariella, following Buckman’s first rule of covariation. In total, one species of nautilid and 38 taxa (25 genera) of ammonites are described, among which five species are documented from Salazac for the first time. In turn, this study provides valuable data for future phylogenetic, biostratigraphical, biogeographical and broad-scale diversity studies.     

A coleoid gladius (Mollusca,Cephalopoda) from the Albian of Normandy (France): A new squid genus and species

A coleoid gladius (Mollusca, Cephalopoda), well preserved in a phosphate nodule, is described from the lower Albian of Normandy (France). The lateral parts of the gladius are considered as the remains of a primary conus. This fossil is part of a gladius of modern type. It is thought to be included in an evolutionary trend leading to the Recent genera, of narrowing of the gladius associated with greater streamlining of the body. The coleoid gladii are almost unknown from the Cretaceous. This coleoid gladius from the Albian of Normandy differs from any known Mesozoic gladius, and thus is named Normanoteuthis inopinata, new genus, new species, within the family Plesioteuthidae.     

The First Iguanodontid Dinosaur Tracks from the Swiss Alps (Schrattenkalk Formation,Aptian)

Until now dinosaur tracks from Switzerland were only known from Triassic and Late Jurassic strata. We report here for the first time the occurrence of ornithopod tracks from the Schrattenkalk Formation (Late Aptian) from the Swiss Central Alps. The locality is situated in an abandoned quarry on the shore of Lake Lucerne close to the village of Beckenried. The steeply inclined surface has more than 50 tracks (in three trackways) of ornithopod dinosaurs that are attributed to iguanodontids. Three trackways can be followed for distances of 25 to 35 m. The lengths the footprints (mean: 30 cm) point to animals ranging in size of from 4 to 6 m, with estimated hip heights between 1.8 and 2 m (hip height 6 FL) and 1.4 to 1.7 m (hip height 5 FL). One of the trackways shows two succesive manus impressions, indicating facultative quadrupedal gait. The track bearing layer consists of shallow water micrites with traces of emersion, and it is overlain by bioclastic grainstones. Previously the Upper Schrattenkalk Member in the Helvetic realm was thought to have formed on a large shelf far away from any continents. The present discovery will shed new light on the paleogeographic position of the Helvetic nappes.