Timurlengia euotica: a new Horse Sized Tyrannosaur Theropod From Turonian Cretaceous Uzbekistan

New tyrannosaur from the mid-Cretaceous of Uzbekistan clarifies evolution of giant body sizes and advanced senses in tyrant dinosaurs

Authors:

Brusatte et al

Abstract:

Tyrannosaurids—the familiar group of carnivorous dinosaurs including Tyrannosaurus and Albertosaurus—were the apex predators in continental ecosystems in Asia and North America during the latest Cretaceous (ca. 80–66 million years ago). Their colossal sizes and keen senses are considered key to their evolutionary and ecological success, but little is known about how these features developed as tyrannosaurids evolved from smaller basal tyrannosauroids that first appeared in the fossil record in the Middle Jurassic (ca. 170 million years ago). This is largely because of a frustrating 20+ million-year gap in the mid-Cretaceous fossil record, when tyrannosauroids transitioned from small-bodied hunters to gigantic apex predators but from which no diagnostic specimens are known. We describe the first distinct tyrannosauroid species from this gap, based on a highly derived braincase and a variety of other skeletal elements from the Turonian (ca. 90–92 million years ago) of Uzbekistan. This taxon is phylogenetically intermediate between the oldest basal tyrannosauroids and the latest Cretaceous forms. It had yet to develop the giant size and extensive cranial pneumaticity of T. rex and kin but does possess the highly derived brain and inner ear characteristic of the latest Cretaceous species. Tyrannosauroids apparently developed huge size rapidly during the latest Cretaceous, and their success in the top predator role may have been enabled by their brain and keen senses that first evolved at smaller body size.

 Nat Geo article also.

Another link.

Turonian/Coniacian Cretaceous Kholokhovchan Flora Shows Angiosperms Penetrating Into Older Ecosystems

Late Cretaceous Kholokhovchan Flora of Northeastern Asia: Composition, age and fossil plant descriptions

Authors:

Herman et al

Abstract:

The Kholokhovchan Flora comes from tuffaceous – terrigenous deposits of the Vetvinskaya Member (Chalbugchan Group) in the Penzhina and Oklan rivers interfluve, Northeastern Russia. The depositional environment of the plant-bearing deposits is interpreted to have been a freshwater lake. The Kholokhovchan Flora hosts 42 fossil plant species belonging to Marchantiopsida, Polypodiopsida, Ginkgoales, Leptostrobales, Bennettitales, Pinales and Magnoliopsida. It is characterised by diverse angiosperms, less diverse conifers and ferns, by the presence of relatively ancient Sphenobaiera, Phoenicopsis and Pterophyllum together with advanced Late Cretaceous Taxodium, Glyptostrobus and angiosperms, among which platanoids are quite diverse. The Kholokhovchan Flora is most similar to Penzhina and Kaivayam floras of the Anadyr-Koryak Subregion and Arman Flora of the Okhotsk-Chukotka volcanogenic belt (Northeastern Russia) and should be dated as Turonian–Coniacian. The Kholokhovchan Flora, that populated volcanic plateaus and intermontane valleys, are characterised by a mixture of ancient “Mesophytic” plants with typical Late Cretaceous “Cenophytic” taxa. This peculiar composition probably reflects a gradual penetration of new angiosperm-dominated plant assemblages into older floras: during the Late Cretaceous, “Cenophytic” assemblages migrated along river valleys and other disturbed habitats into the interior of Asia, eventually occupying volcanogenic uplands, and in places replacing the “Mesophytic” fern-gymnospermous communities that existed there. Two new angiosperm species, as well as four the most characteristic conifers of the Kholokhovchan Flora, are described: Cupressaceae gen. et sp. indet. cf. Widdringtonites sp., Taxodium cf. olrikii, Taxodium sp., Glyptostrobus sp., Ettingshausenia vetviensis sp. nov. and Parvileguminophyllum penzhinense sp. nov.

What Drove Sea Level Change During the Turonian Cretaceous Greenhouse Climate?

What drove sea-level fluctuations during the mid-Cretaceous greenhouse climate?

Authors:

Wendler et al

Abstract:

The major states, in which Earth's climate operates, i.e., icehouse, greenhouse and hothouse, are epochs of tens of millions of years. These states set long-term boundary conditions that need to be considered for climate and sea-level interpretations. This paper summarizes the conceptual models for hydrological cycling derived from the characteristics of these three climate states. While glacio-eustatic forcing of sea-level changes under icehouse climate conditions is fairly well understood, the drivers of eustatic sea-level fluctuations under greenhouse conditions remain enigmatic. This lack of understanding may be related to incoherencies in the current ideas about the impact of accelerated hydrological cycling on sea level under greenhouse climate conditions.

As an example for a greenhouse climate, we review evidences that link proxies for climate and sea level for the intensely studied, but controversially discussed, mid-Cretaceous sea-level history. Based on sequence stratigraphy and a recently published high-precision timescale, we demonstrate that the late Middle Turonian Pewsey δ13C isotope maximum represents a major transgression, not a regression as previously stated, which conflicts with the interpretation of a co-occurring δ18O maximum to reflect a short glacial episode. This contradiction can be solved by the concept, presented here, that dominance of aquifer-eustasy characterized sea-level forcing during the Turonian greenhouse climate, despite a possible, though contentious, sporadic presence of minor ice sheets. The effects of temperature and ice volume both lead to a pronounced δ18Ocarb maximum during glacio-eustatic regressions. In contrast, the opposing effects of temperature and groundwater volume on oxygen-isotope fractionation lead to a δ18Ocarb maximum during aquifer-eustatic transgressions. We suggest that, throughout Earth history, both aquifer-eustatic and glacio-eustatic forcing formed a combined sea-level response, with dominance of aquifer-eustasy being typical for the greenhouse climate mode. During the icehouse mode, aquifer-eustasy apparently remains active as a background process, but is outpaced by the glacio-eustatic effect.

Did Modern Birds Evolve in Turonian/Coniacian Cretaceous South America and Spread Worldwide After K-Pg/K-T Mass Extinction

New research led by the American Museum of Natural History reveals that the evolution of modern birds was greatly shaped by the history of our planet's geography and climate. The DNA-based work, published today in the journal Science Advances, finds that birds arose in what is now South America around 90 million years ago, and radiated extensively around the time of the Cretaceous-Paleogene extinction event that killed off the non-avian dinosaurs. The new research suggests that birds in South America survived this event and then started moving to other parts of the world via multiple land bridges while diversifying during periods of global cooling.

"Modern birds are the most diverse group of terrestrial vertebrates in terms of species richness and global distribution, but we still don't fully understand their large-scale evolutionary history," said Joel Cracraft, a curator in the Museum's Department of Ornithology and co-author of the paper. "It's a difficult problem to solve because we have very large gaps in the fossil record. This is the first quantitative analysis estimating where birds might have arisen, based on the best phylogenetic hypothesis that we have today."

Cracraft and lead author Santiago Claramunt, a research associate in the Museum's Department of Ornithology, analyzed DNA sequences for most modern bird families with information from 130 fossil birds to generate a new evolutionary time tree.

link.

Mosaiceratops azumai: a new Basal Neoceratopsian From Turonian/Campanian Cretaceous China

A psittacosaurid-like basal neoceratopsian from the Upper Cretaceous of central China and its implications for basal ceratopsian evolution

Authors:

Zheng et al

Abstract:

Psittacosauridae (parrot-beaked dinosaurs) represents the first major radiation of ceratopsians (horned dinosaurs). However, psittacosaurids are divergent from the general morphology found in other ceratopsians, and this has resulted in their uncertain systematic position among ceratopsians. Here we describe a new basal neoceratopsian dinosaur, Mosaiceratops azumai gen. et sp. nov. based on a partial semi-articulated skeleton recovered from the Upper Cretaceous Xiaguan Formation of Neixiang County, Henan Province, China. Although our phylogenetic analysis supports this taxon as the most basal neoceratopsian, Mosaiceratops exhibits many features previously considered unique to the Psittacosauridae among the basal Ceratopsia. These include a relatively highly positioned external naris, a proportionally large premaxilla, the nasal extending ventral to the external naris, slender postorbital and temporal bars, a large notch between the basal tubera, and the edentulous premaxilla. Thus, the discovery of Mosaiceratops reduces the morphological disparity between the Psittacosauridae and other basal ceratopsians. Character optimization suggests that basal neoceratopsians have re-evolved premaxillary teeth; a major reversal previously unknown in any dinosaur clade. The new specimen also highlights the mosaic nature of evolution among early ceratopsians and supports the phylogenetic hypothesis that the Psittacosauridae is a relatively derived clade, rather than the most basal group of the Ceratopsia.

The Albian/Maastrichtian Cretaceous Vertebrate Fauna of India's Cauvery Basin

Cretaceous vertebrate fauna of the Cauvery Basin, southern India: Palaeodiversity and palaeobiogeographic implications

Author:

Verma

Abstract:

The vertebrate fauna from the late Albian to Maastrichtian succession of the Cauvery Basin, south India has been known since 1845, but it received only scant attention as compared to the vertebrates already known from the Deccan volcanic province of peninsular India. Recent fossil discoveries appear to support the emergence of significantly diverse marine and non-marine vertebrates comprising fishes, frogs, reptiles (ichthyosaurs, plesiosaurs, turtles, crocodiles and dinosaurs) and a mammal from the Cauvery Basin have revived the interest in the fauna of the basin as it has significant implications for understanding the palaeobiogeography of India. The latest Albian to Turonian marine vertebrates such as sharks, ichthyosaurs and plesiosaurs show a wide geographic distribution and marine territory, while sharks are typically cooler water fauna of high palaeolatitudes. The latest Maastrichtian non-marine vertebrates especially turtles, crocodiles, dinosaurs and a mammal are considered to show mixed Gondwanan and Laurasian affinities thus providing new lines of evidence in favour of a latest Cretaceous biotic links between India and the neighbouring continents. An overview of the vertebrate faunal diversity of the Cretaceous sequences of the Cauvery Basin and its palaeobiogeographic considerations are presented.

The Postcranial Skeleton of Elamosaurid Libonectes morgani From Turonian Cretaceous Texas

Postcranium of the paradigm elasmosaurid plesiosaurian Libonectes morgani (Welles, 1949)

Authors:

Sachs et al

Abstract:

Elasmosauridae constitutes one of the most immediately recognizable plesiosaurian radiations. Their distinctive body plan represents the popular model for Plesiosauria, and is typified by an osteological morphology especially adapted for hyper-elongation of the neck. Nevertheless, many archetypal elasmosaurids are known only from incomplete and/or inadequately documented material, a problem that has contributed to their uncertain intra-clade relationships. A prime example of this is Libonectes morgani from the Upper Cretaceous of Texas, USA, which is frequently presented as an elasmosaurid structural proxy because of its three-dimensionally preserved holotype skull. Perplexingly though, both the taxonomic diagnosis and phylogenetic placement of L. morgani rely primarily upon the cervical vertebrae, together with the pectoral girdle and forelimb, yet most of these elements are now lost and figured only as line drawings. We therefore reviewed the remnant postcranial skeleton of L. morgani first-hand with the objective of clarifying its defining character states. Our observations showed that the existing diagnosis of L. morgani is indeed inadequate. Moreover, the only identifiable autapomorphies occurred within the axial skeleton. This concurred with an examination of character scores used in published plesiosaurian phylogenies, and highlights the persistent significance of postcranial elements for discriminating elasmosaurid taxa.

Petrified Wood Growth Indices as Climate Proxies For Cenomanian/Turonian Cretaceous Australia

Wood growth indices as climate indicators from the Upper Cretaceous (Cenomanian–Turonian) portion of the Winton Formation, Australia

Authors:

Fletcher et al

Abstract:

Although the mid- to Late Cretaceous is regarded as a global warm period, increasingly a more complex picture of warming and cooling is emerging. New techniques allow more precise dating of terrestrial localities, opening opportunities for using climate proxy approaches on terrestrial fauna and flora to better capture the complexity of Cretaceous climate. Here an attempt is made to understand the seasonality and inter-annual variability of two newly dated localities from the upper preserved portion (Cenomanian–Turonian) of the Winton Formation, Australia. Primarily quantitative approaches to palaeodendrology are used. The results suggest both seasonality and high variability in climate conditions that affect growth between years, including evidence for floods. The longest series (QM F44338) suggests oscillatory patterns of good and poor growth in a 15 year alternating cycle similar to the contemporary Pacific Decadal Oscillation, although other potential explanations should be considered and tested.

Wood Growth Rings From Cenomanian/Turonian Cretaceous Australia as Paleoclimate Indicators

Wood growth indices as climate indicators from the Upper Cretaceous (Cenomanian–Turonian) portion of the Winton Formation, Australia

Authors:

Fletcher et al

Abstract:

Although the mid- to Late Cretaceous is regarded as a global warm period, increasingly a more complex picture of warming and cooling is emerging. New techniques allow more precise dating of terrestrial localities, opening opportunities for using climate proxy approaches on terrestrial fauna and flora to better capture the complexity of Cretaceous climate. Here an attempt is made to understand the seasonality and inter-annual variability of two newly dated localities from the upper preserved portion (Cenomanian–Turonian) of the Winton Formation, Australia. Primarily quantitative approaches to palaeodendrology are used. The results suggest both seasonality and high variability in climate conditions that affect growth between years, including evidence for floods. The longest series (QM F44338) suggests oscillatory patterns of good and poor growth in a 15 year alternating cycle similar to the contemporary Pacific Decadal Oscillation, although other potential explanations should be considered and tested.

Palaeoenvironmental Turnover Across the Cenomanian-Turonian Cretaceous Transition

Palaeoenvironmental turnover across the Cenomanian-Turonian transition in Oued Bahloul, Tunisia: Foraminifera and geochemical proxies

Authors:

Reolid et al

Abstract:

The integrated analysis of foraminiferal assemblages, geochemical proxies, and stable isotopes in the Oued Bahloul section (Tunisia) allowed us to reconstruct the environmental turnover across the Cenomanian–Turonian boundary. An increase in palaeoproductivity proxies (P/Ti, U/Al, Sr/Al) and in δ13C values, and a decrease in foraminiferal diversity and δ18O values mark the beginning of the Oceanic Anoxic Event 2 (OAE2) at the Rotalipora cushmani and Whiteinella archaeocretacea biozones boundary. Eutrophic conditions at the seafloor and in the water column are evidenced by high proportions of buliminids and the replacement of planktic oligotrophic specialist Rotalipora by eutrophic opportunist Hedbergella. The enrichment in organic matter and redox sensitive elements, together with the abundance of low-oxygen tolerant benthic foraminifera, indicate dysoxic conditions in the deep-water column and at the seafloor (higher Uaut than Moaut). Among planktic foraminifera, deep- and intermediate-dwellers disappear (Rotalipora and Globigerinelloides), and surface-dwellers proliferate (Hedbergella). The persistency of the poorly oxygenated conditions during the W. archaeocretacea Biozone locally produced euxinic conditions where MoEF and Moaut reach high values, diversity presents minimum values, and benthic foraminifera temporarily disappear. The maximum percentage of heterohelicids indicates a stratified water column with a well-developed oxygen minimum zone. Improved oxygen conditions returned in the upper part of the W. archaeocretacea Biozone and Helvetoglobotruncana helvetica Biozone, with a slow recovery of foraminiferal assemblages, decrease in eutrophic genera (Heterohelix) and increase in mesotrophic genera (Whiteinella). A gradual increase in δ18O values suggests decreased temperatures in surface waters. The OAE2 has been attributed to global temperature changes and palaeoceanographic reorganization. The poor mixing of surface and deep waters and enhanced primary productivity related to global warming —associated with increasing continental weathering and nutrient runoff— may have favored the eutrophication of the ocean and the expansion of the oxygen minimum zone.

Environmental Changes in the Western Interior Seaway Across the Cenomanian/Turonian Cretaceous Boundary

Paleoenvironmental and paleoceanographic changes across the Cenomanian–Turonian Boundary Event (Oceanic Anoxic Event 2) as indicated by foraminiferal assemblages from the eastern margin of the Cretaceous Western Interior Sea

Authors:

Elderbak et al

Abstract:

Two sites near the eastern margin of the Cretaceous Western Interior Sea (WIS) were investigated. The section at Cuba, Kansas (CK) is ~ 630 km east of the GSSP for the Cenomanian/Turonian boundary at Rock Canyon, Colorado (RC), and the section near Sioux City, Iowa (SCI) is ~ 315 km northeast of the Cuba site. Surprisingly, planktic foraminifera dominate all the studied samples despite the relative proximity of the sites to the paleo-shoreline and presumed neritic water depths. Such dominance suggests inhospitable benthic environments, and benthic foraminiferal assemblages indicate that seafloor oxygen in the WIS decreased eastward. Therefore, the hypothesis of an influx of freshwater into the WIS from the western margin forming a fresh water cap that diminished eastward is not supported. Benthic foraminifera are scarce in most studied samples and species diversity is low. In the CK section, diversity and abundance increase abruptly in the uppermost Cenomanian Benthonic Zone at the initiation of the δ13Corg positive excursion marking the onset of Oceanic Anoxic Event (OAE 2). In the SCI section, however, the Benthonic Zone is recognized only by presence of Nodosaria bighornensis that has a stratigraphic range restricted to this interval; other benthic taxa are very rare or absent. The favorable conditions of the Benthonic Zone were short-lived. While relatively diverse planktic foraminiferal assemblages, including keeled species, characterize the initial δ13C excursion at the CK site, dwarfed specimens of Heterohelix and Hedbergella dominate the assemblages at the more proximal Sioux City site. Furthermore, most of the biostratigraphic events recognized in the basin center RC section can be traced into the CK section, but not into the SCI section, including the Rotalipora spp. and Globigerinelloides bentonensis extinctions, the Heterohelix shift event, and the brief benthic recovery event. Correlation between eastern WIS sites shows that the SCI section is thicker, suggesting a major sediment source to the east. This may explain the inhospitable benthic conditions and development of a ‘dead zone’ (seasonal hypoxia) analogous to the modern shelf of the northern Gulf of Mexico proximal to active discharge of the Mississippi River. Development of estuarine circulation in the WIS provided the eastern part of the basin with input of calcareous plankton from the south including planktic foraminifera. Foraminiferal assemblages, total organic carbon (TOC), and δ13C data of the studied sections suggest a two-fold history of Greenhorn transgression and OAE 2 development. The initial phase is a global signal characterized by a positive δ13C excursion, low TOC values, and high foraminiferal species diversity. The second phase is characterized by overprinting by local conditions in the WIS, including high fluvial input, relatively high TOC values, and low foraminiferal species diversity. These findings suggest that the eastern margin records unique depositional and biotic environments further revealing the dynamic and complex nature of the WIS and its sedimentary cycles.

Rapid Faunal Change Across the Cenomanian/Turonian Cretaceous Boundary in Egypt

Stratigraphic significance of rapid faunal change across the Cenomanian–Turonian boundary in the Eastern Desert, Egypt

Author:

Nagm

Abstract:

A significant and rapid faunal change across the Cenomanian–Turonian boundary in the Eastern Desert of Egypt has been recognized by reconstructing the stratigraphic ranges of macroinvertebrates within the upper Cenomanian–lower Turonian Galala and Abu Qada formations. The faunal change initiated with a considerable loss of taxa during the late Cenomanian at the top of the Neolobites vibrayeanus ammonite zone, coinciding with sequence boundary SB Ce 5, ∼400 ka before the Cenomanian–Turonian boundary (93.9 Ma). Only 10% of the taxa that existed during the late Cenomanian have been recorded from lower Turonian strata. The changes in the macroinvertebrate faunas continued across the Cenomanian–Turonian boundary and new faunal associations evolved after the earliest Turonian Vascoceras proprium ammonite zone of (∼200 ka after the Cenomanian–Turonian boundary). Therefore, the crisis that caused this faunal change around the Cenomanian–Turonian boundary over approximately 600 ka. The timing of the macrofaunal change recognized in the study area completely overlaps with the well-known Oceanic Anoxic Event (OAE) 2 and most probably it is one of the effects of the major environmental perturbations (critical warming, high atmospheric CO2 concentration, and ocean water acidification) associated with this event. In addition, the sequence-stratigraphic analysis shows strong correlation exists between pattern of first and last occurrences of macroinvertebrate faunas and sea-level changes. Therefore, the oceanographic changes (rapid sea-level rise) may have also contributed to the Cenomanian–Turonian faunal change in the study area.

Reassessment of Mosasaurus gracilis From Turonian Cretaceous England

Reassessment of Turonian mosasaur material from the ‘Middle Chalk’ (England, U.K.), and the status of Mosasaurus gracilis Owen, 1849

Authors:

Street et al

Abstract:

The first described genus of mosasaur, Mosasaurus hoffmannii, has been coarsely diagnosed and defined since its creation, with numerous specimens and new species being assigned to the genus with little or no reference to, and thus few real similarities with, the generic type specimen. One of the earliest examples of a weakly defined and diagnosed species assigned to the genus is Mosasaurus gracilis. Location and examination of the various assigned specimens and the holotype indicate that M. gracilis shares more characters, such as a short rostrum on the dentary anterior to the first teeth, with russellosaurine mosasaurs. In addition, M. gracilis is known from Turonian deposits, whereas other species belonging to Mosasaurus are upper Campanian–Maastrichtian in age. Based on the evidence of shared characters and contemporaneity, we suggest that M. gracilis be removed from Mosasaurus because it shares more affinities with members of the Russellosaurina. This represents the first step in the very necessary process of untangling the alpha taxonomy, and subsequently the complete systematics, of the genus Mosasaurus hoffmannii.

/Orbitally/ Forced Sea Level Changes During the Turonian/Coniacian Cretaceous?!

Orbitally forced sea-level changes in the upper Turonian–lower Coniacian of the Tethyan Himalaya, southern Tibet

Authors:

Chen et al

Abstract:

Although the mid-Cretaceous is considered to be a typical interval of greenhouse climate and high sea level, cooling events associated with regressions were inferred in recent years. We conducted a biostratigraphic, chemostratigraphic, sequence stratigraphic and cyclostratigraphic investigation of upper Turonian–lower Coniacian marine strata in the Tethyan Himalaya zone, to retrace the sea-level variations and to clarify their global correlations. According to the planktonic foraminiferal zonation, the studied interval is part of the late Turonian–early Coniacian Marginoruncana sigali and D. concavata Zones. The carbon isotope curve shows a good correlation to reference curves in the Boreal and western Tethys realms with all major and minor late Turonian δ13C events identified, indicating that the C-isotope curve provides an excellent tool for global stratigraphic correlation in the Turonian. Based on the lithological variations of clastic input and physical and chemical proxies, the succession is divided into two third order and eight fourth order sequences. Spectral analysis indicates that fourth order sea-level changes were linked to the astronomically stable 405-kyr eccentricity cycle. Comparison with classic global sea-level curves, we suggest that late Turonian–early Coniacian sea-level changes along the southeastern Tethyan margin were controlled by eustasy. The significant regressions during ∼90–89.8 Ma and ∼92–91.4 Ma, which are recorded in different continents, may be interpreted as the result of continental ice expansion, giving some support to the notion that ephemeral polar ice sheets existed even in the super-greenhouse world.

The Arctic Formed Black Shale During Cenomanian-Turonian Cretaceous Oceanic Anoxic Event (OAE 2)

Arctic black shale formation during Cretaceous Oceanic Anoxic Event 2

Authors:

Lenninger et al

Abstract:

The Late Cretaceous Oceanic Anoxic Event 2 (OAE2) represents a major perturbation of the global carbon cycle caused by the widespread deposition of organic-rich black shales. Although the paleoceanographic response and the spatial extent of bottom-water anoxia in low and mid-paleolatitudes are reasonably well constrained for OAE2, similar data from high paleolatitudes are lacking. Here, we present palynostratigraphy and organic-carbon isotope stratigraphy from the Sverdrup Basin, Axel Heiberg Island (Canada). It is shown that episodes of high marine organic-carbon burial at paleolatitudes of ∼70°N is contemporaneous with the widely observed occurrence of black shale deposition during OAE2. Paleontological, lithological, and geochemical data indicate normal marine conditions with persistent anoxic bottom waters during OAE2. The results imply that the high marine primary productivity pulse during OAE2 may have caused massive organic-carbon burial on the Arctic shelf in general, with important implications for hydrocarbon source-rock distribution in the Arctic region.

Itemirus: a Dromaeosaur From Turonian Cretaceous Uzbekistan

Dromaeosauridae (Dinosauria: Theropoda) from the Bissekty Formation (Upper Cretaceous: Turonian) of Uzbekistan and the phylogenetic position of Itemirus medullaris Kurzanov, 1976

Authors:

Sues et al

Abstract:

Skeletal remains of dromaeosaurid theropods are uncommon in the richly fossiliferous continental strata of the Upper Cretaceous (Turonian) Bissekty Formation of the Kyzylkum Desert in Uzbekistan. The phylogenetic position of the first published specimen, a partial braincase designated as the holotype of Itemirus medullaris Kurzanov, 1976, has long been contentious. Our examination of the specimen supports its attribution to Dromaeosauridae. Additional, mostly well-preserved dromaeosaurid skeletal remains from the Bissekty Formation include cranial bones, teeth, vertebrae, and some podial elements. They are tentatively referred to the same taxon, Itemirus medullaris, and establish the presence of dromaeosaurid paravians in present-day Central Asia during the Turonian.

Global Environmental Response to the Cenomanian–Turonian Cretaceous Oceanic Anoxic Event was not Uniform

Geographically different oceanographic responses to global warming during the Cenomanian–Turonian interval and Oceanic Anoxic Event 2

Authors:

Thomas et al

Abstract:

Oceanic Anoxic Event (OAE) 2 coincided with the Cenomanian–Turonian boundary ~ 93.9 Ma, and was one of the two most prominent and globally significant of the major mid-Cretaceous OAEs. A confluence of global warming, major large igneous province volcanism, and intensified hydrologic cycling preconditioned the earth system for widespread preservation of organic matter during OAE2; however the ultimate necessary ingredient was enhanced nutrient availability in oceanic surface waters. Here we present new Cenomanian–Turonian interval seawater Neodymium isotope data from the proto-Indian Ocean that demonstrates increased water column stratification during the pre- and post-OAE2 interval, punctuated by a transient decrease in this stratification immediately prior to the onset of OAE2 recorded at Ocean Drilling Program Site 763. The direct oceanographic responses to climate change on both longer- and short-term time scales observed in this region are distinct from those recorded in the northern, tropical and southern Atlantic basins. The transient de-stratification of the water column in the eastern proto-Indian Ocean likely did not contribute to the accumulation of organic-rich sediments in the region, indicating that weathering and/or hydrothermal inputs promoted enhanced surface water nutrient levels and hence primary productivity.

The Paleoclimate of Cenomanian to Turonian Cretaceous of Western Queensland, Australia

PALEOCLIMATE OF THE LATE CRETACEOUS (CENOMANIAN–TURONIAN) PORTION OF THE WINTON FORMATION, CENTRAL-WESTERN QUEENSLAND, AUSTRALIA: NEW OBSERVATIONS BASED ON CLAMP AND BIOCLIMATIC ANALYSIS

Authors:

Fletcher et al

Abstract:

Although there is an emerging consensus about global climate patterns during the Cretaceous, details about the climate in Australia at this time are poorly resolved, and estimates for terrestrial climate are scarce. Using Climate Leaf Analysis Multivariate Program (CLAMP) and Bioclimatic Analysis (BA) on plant fossils from the mid- to Upper Cretaceous Winton Formation, central-western Queensland, and working within the context of global paleoclimatic reconstructions and the vertebrate fauna from this unit, we have improved the temporal and geographic resolution of Australia's Cretaceous climate. During the time that the Cenomanian–Turonian portion of the Winton Formation was deposited, the climate in central-western Queensland was warm, wet, and relatively equable. Frost would have been extremely uncommon, if it occurred at all, and much of the year would have been favorable for plant growth. These results are consistent with both previous isotope records for northern Australia, and the fauna of the Winton Formation, and are in keeping with current reconstructions of global Cretaceous climates.

Cenomanian-Turonian Cretaceous Paleooceanic Environmental Conditions in South Texas

The Cenomanian-Turonian Eagle Ford Group of South Texas: Insights on timing and paleoceanographic conditions from geochemistry and micropaleontologic analyses

Authors:

Denne et al

Abstract:

The interbedded organic-rich marls and limestones of the Eagle Ford Group of South Texas were deposited on the shelf of the Central Texas Platform during the upper Cenomanian through the Turonian. Micropaleontological analyses of thin-sections and residue samples from subsurface cores taken in Atascosa and Karnes counties yielded 13 biostratigraphic datums, which were integrated with calcareous nannofossil datums, stable carbon isotopic and bulk inorganic geochemical analysis analysis to gain an understanding of the paleoceanographic conditions of the study area and their relationship to regional and global events. The paired thin-section / residue sampling was necessitated by poor recovery of planktonic foraminifera in washed samples, which were, however, abundant in most thin-sections. Lower Eagle Ford marls were deposited under euxinic conditions produced by a stratified water column. Periodic enhanced water column mixing increased oxygen levels and surface-water primary productivity, which promoted calcite diagenesis and generation of limestones containing calcispheres and radiolaria. An oxygenated bottom water mass entered the basin in the uppermost Cenomanian prior to the onset of Oceanic Anoxic Event (OAE) 2, causing a spike in benthic foraminiferal diversity and decreasing preservation of organic matter. Although the lower portion of the upper Eagle Ford is age-equivalent to OAE2 as indicated by positive shift in δ13Corg, it contains less organic matter and evidence of more oxygen than the lower Eagle Ford, so deposition of the Eagle Ford black shales is not contemporaneous to OAE2.

Turonian Cretaceous Sea Level Transgression/Regressions *NOT* Tied to Extinctions

A high-resolution carbon-isotope record of the Turonian stage correlated to a siliciclastic basin fill: Implications for mid-Cretaceous sea-level change

Authors:

Uličný et al

Abstract:

Turonian strata of the Bohemian Cretaceous Basin, Central Europe, preserve a basin-scale record of shoreline transgressions and regressions, previously interpreted to have been strongly influenced by short-term eustatic cycles. Here, nearshore siliciclastic strata in two separate sub-basins are correlated to a multi-stratigraphic dataset generated from a new research core (Bch-1) drilled in offshore marine sediments of the central basin. A high-resolution δ13Corg record from Bch-1 is presented along with major- and minor-element proxies, TOC, carbonate content, terrestrial to marine palynomorph ratios, and detailed macro- and microfossil biostratigraphy. The 400 m thick Turonian through Lower Coniacian interval permits correlation to the highest-resolution C-isotope curves available: all carbon-isotope events demonstrated by δ13Ccarb studies in the British Chalk, NW Germany and other reference sections in Europe are recognized in the δ13Corg curve from Bch-1.

A number of short-term, basin-wide regressions in the Bohemian Cretaceous Basin, most likely reflecting eustatic falls, show a recurrence interval of 100 kyr or less. This is an order of magnitude shorter than the timing of sea-level falls inferred from the New Jersey margin and the Apulian platform, interpreted to be driven by glacioeustacy. The estimated magnitude of the Bohemian Basin sea-level falls, typically 10–20 m and generally less than 40 m, indicates that the 2.4 Myr period suggested by others to generate 3rd-order cycles, is too long to be the principal cycle generating unconformities in rapidly-subsiding basins, where the rate of eustatic fall must exceed the subsidence rate. Unconformities in low-accommodation settings such as passive margins most likely represent amalgamated records of multiple cycles of sea-level fluctuations of 100 kyr scale, recognizable only in high-resolution datasets from expanded successions.

Comparison of the δ13C excursions to the interpreted sea-level record has not yielded a clear causal link. A long-term ‘background’ δ13C cycle shows a duration close to the 2.4 Myr long-eccentricity cycle, and shorter-term (1 Myr scale) highs and lows in δ13C appear to broadly correspond to intervals characterised by more pronounced short-term sea-level highs and lows, respectively. However, on the scale of intermediate to short-term δ13C fluctuations, no systematic relationship between δ13C and sea-level change can be demonstrated.