Lower Cretaceous (lower + cretaceous)

Distribution by Scientific Domains


Selected Abstracts


A New, Weil-Preserved Species of Glaresidae (Coleoptera: Scarabaeoidea) from the Jehol Biota of China

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 4 2010
BAI Ming
Abstract: Glaresis orthochilus sp. nov. (Scarabaeoidea: Glaresidae), the best preserved glaresid fossil, is described and illustrated from the Yixian Formation of western Liaoning province, north,east China. Glaresidae, the sister group of all extant Scarabaeoidea was established in the Upper Jurassic/Lower Cretaceous and contained larger species than those found today. [source]


AN EARLY HERBIVOROUS LIZARD FROM THE LOWER CRETACEOUS OF JAPAN

PALAEONTOLOGY, Issue 2 2008
SUSAN E. EVANS
Abstract:, The Lower Cretaceous Tetori Group of Japan has yielded diverse freshwater and terrestrial vertebrate assemblages. The most productive small vertebrate locality is the ,Kaseki-Kabe' or ,fossil-bluff' at Kuwajima, Hakusan City, Ishikawa Prefecture. These deposits have produced at least six distinct lizard taxa of which one, described and named here as Kuwajimalla kagaensis, has lanceolate denticulate teeth convergent on those of the living Iguana. This type of dentition is rare among living lizards and is usually considered indicative of herbivory and, more specifically, folivory. Kuwajimalla kagaensis provides the earliest unambiguous record of squamate herbivory. Comparisons with modern and fossil lizards suggest that Kuwajimalla may be an early relative of the macrocephalosaurines, a group of large herbivores well represented in the Upper Cretaceous of Mongolia. [source]


ANACORACID SHARKS FROM THE ALBIAN (LOWER CRETACEOUS) PAWPAW SHALE OF TEXAS

PALAEONTOLOGY, Issue 4 2007
MIKAEL SIVERSON
Abstract:, Recent collecting from the Pawpaw Shale in north-east Texas has yielded several hundred teeth of anacoracid sharks. The material allows for a much-needed revision of the Late Albian anacoracids from North America. The previously recognized Squalicorax sp., also referred to as S. volgensis in more recent publications, is a mix of two different species: S. priscoserratus sp. nov. and S. pawpawensis sp. nov. In addition to these two new species, a single tooth is assigned to S. aff. S. baharijensis. Our data indicate that anacoracids were a considerably more diverse group in the North American Cretaceous than previously thought. We attribute much of the underestimation of diversity to vague species concepts, poor preparation techniques and the associated lack of attention to certain dental features, in particular neck morphology, root surface porosity and the root's vascularization. [source]


HIGHER SYSTEMATICS OF SCORPIONS FROM THE CRATO FORMATION, LOWER CRETACEOUS OF BRAZIL

PALAEONTOLOGY, Issue 1 2007
FEDERICA MENON
Abstract:, Several new specimens of Protoischnurus axelrodorum Carvalho and Lourenço and Araripescorpius ligabuei Campos from the Crato Formation, Brazil, are described. The preservation and recognition of new morphological features allows a re-diagnosis of both species and a modification of their familial placement. Protoischnurus axelrodorum is the oldest species belonging to the scorpionoid family Hemiscorpiidae Pocock (= Ischnuridae Simon; =,Liochelidae Fet and Bechly) and the first Cretaceous record. It was originally placed in the extinct family Protoischnuridae Carvalho and Lourenço, which is here synonymized with Hemiscorpiidae. Araripescorpius ligabuei, now assigned to Chactidae Pocock, is the first chactoid recorded for the Cretaceous of Brazil. These findings confirm that the lineages of two modern families date back at least to the Early Cretaceous and, considering their current distribution, were probably present before the break-up of the supercontinent Gondwana. Palaeoecological inferences indicate the presence of tropical habitats in the vicinity of the Crato lake/lagoon. [source]


A NEW ELASMOBRANCH ASSEMBLAGE FROM THE LOWER CRETACEOUS OF THAILAND

PALAEONTOLOGY, Issue 3 2006
HENRI CAPPETTA
Abstract:, The discovery of a new elasmobranch assemblage from the Lower Cretaceous of Thailand allows expansion of the faunal list and refinement of our knowledge of the dental morphological features of some previously described taxa. The root morphology of Thaiodus is now known and a more complete description of the dentition of the genus Heteroptychodus, known formerly by a single tooth from Japan, is given. A new genus and species, Acrorhizodus khoratensis, characterized by teeth of very special morphology is described. Besides these taxa, some teeth of a genus probably close to Hybodus, but with more bulbous teeth, are present. Owing to the sedimentological characters of the deposits and the associated fauna (dinosaurs), it is probable that this elasmobranch fauna lived in a freshwater or brackish environment. The simultaneous occurrence of teeth of Heteroptychodus in Thailand and Japan favours the existence of a large continental area in south-east Asia during the Early Cretaceous. [source]


Diagenesis of the Amposta offshore oil reservoir (Amposta Marino C2 well, Lower Cretaceous, Valencia Trough, Spain)

GEOFLUIDS (ELECTRONIC), Issue 3 2010
E. PLAYÀ
Abstract Samples from the Amposta Marino C2 well (Amposta oil field) have been investigated in order to understand the origin of fractures and porosity and to reconstruct the fluid flow history of the basin prior, during and after oil migration. Three main types of fracture systems and four types of calcite cements have been identified. Fracture types A and B are totally filled by calcite cement 1 (CC1) and 2 (CC2), respectively; fracture type A corresponds to pre-Alpine structures, while type B is attributed to fractures developed during the Alpine compression (late Eocene-early Oligocene). The oxygen, carbon and strontium isotope compositions of CC2 are close to those of the host-rock, suggesting a high degree of fluid-rock interaction, and therefore a relatively closed palaeohydrogeological system. Fracture type C, developed during the Neogene extension and enlarged by subaerial exposure, tend to be filled with reddish (CS3r) and greenish (CS3g) microspar calcite sediment and blocky calcite cement type 4 (CC4), and postdated by kaolinite, pyrite, barite and oil. The CS3 generation records lower oxygen and carbon isotopic compositions and higher 87Sr/86Sr ratios than the host-limestones. These CS3 karstic infillings recrystallized early within evolved-meteoric waters having very little interaction with the host-rock. Blocky calcite cement type 4 (CC4 generation) has the lowest oxygen isotope ratio and the most radiogenic 87Sr/86Sr values, indicating low fluid-rock interaction. The increasingly open palaeohydrogeological system was dominated by migration of hot brines with elevated oxygen isotope ratios into the buried karstic system. The main oil emplacement in the Amposta reservoir occurred after the CC4 event, closely related to the Neogene extensional fractures. Corrosion of CC4 (blocky calcite cement type 4) occurred prior to (or during) petroleum charge, possibly related to kaolinite precipitation from relatively acidic fluids. Barite and pyrite precipitation occurred after this corrosion. The sulphur source associated with the late precipitation of pyrite was likely related to isotopically light sulphur expelled, e.g. as sulphide, from the petroleum source rock (Ascla Fm). Geofluids (2010) 10, 314,333 [source]


TURBIDITE, SLUMP AND DEBRIS FLOW DEPOSITS AT THE KALCHINSKOE AND ZIMNEE OILFIELDS, WEST SIBERIAN BASIN

JOURNAL OF PETROLEUM GEOLOGY, Issue 1 2005
S. F. Khafizov
This paper discusses specific facies associated with Cretaceous deep-water slumps and sandstone intrusions in the West Siberian Basin. The slumps were formed during sea-level falls when storms caused sediment masses to be discharged into deep-water areas where they imposed a significant load on the underlying semi-consolidated black shales, deforming and partially destroying them. Multiple slump / avalanche events are observed at the boundary between the Lower Cretaceous (Neocomian) and Upper Jurassic (Tithonian) sequences and form potential targets for oil exploration. High-resolution sequence stratigraphic analyses show that both slump and distal fans are genetically related to lower slope/basin floor sediments and were deposited during regressions and subsequent lowstands. Two key depositional environments are recognized: the proximal parts of fans, where the most prospective potential reservoirs are found; and the more distal parts of slumps, which are principally composed of deformed shale clasts in a silt-mudstone matrix. A third facies ("slump head") is only observed on seismic profiles and is probably related to horizontally displaced "shingled" semi-consolidated black shales. [source]


The oldest reptile in amber: a 120 million year old lizard from Lebanon

JOURNAL OF ZOOLOGY, Issue 1 2002
E. N. Arnold
Abstract Animals enclosed in amber often provide a unique insight into their surface structure. Such fossils of reptiles are rare and usually not extremely ancient, the earliest being no more than 40 million years (my). A recently discovered 120 my lizard from the Lower Cretaceous of Lebanon provides direct evidence that several common external features of autarchoglossan lizards had evolved by this time. Ecomorphology indicates that the lizard concerned had considerable climbing ability on open surfaces and perhaps in vegetation, and probably lived in a mesic forested environment, something supported by associated plant and invertebrate remains. [source]


A NEW ELASMOBRANCH ASSEMBLAGE FROM THE LOWER CRETACEOUS OF THAILAND

PALAEONTOLOGY, Issue 3 2006
HENRI CAPPETTA
Abstract:, The discovery of a new elasmobranch assemblage from the Lower Cretaceous of Thailand allows expansion of the faunal list and refinement of our knowledge of the dental morphological features of some previously described taxa. The root morphology of Thaiodus is now known and a more complete description of the dentition of the genus Heteroptychodus, known formerly by a single tooth from Japan, is given. A new genus and species, Acrorhizodus khoratensis, characterized by teeth of very special morphology is described. Besides these taxa, some teeth of a genus probably close to Hybodus, but with more bulbous teeth, are present. Owing to the sedimentological characters of the deposits and the associated fauna (dinosaurs), it is probable that this elasmobranch fauna lived in a freshwater or brackish environment. The simultaneous occurrence of teeth of Heteroptychodus in Thailand and Japan favours the existence of a large continental area in south-east Asia during the Early Cretaceous. [source]


First Mesozoic Scutigeromorph Centipede, from the Lower Cretaceous of Brazil

PALAEONTOLOGY, Issue 3 2001
Heather M. Wilson
The first Mesozoic scutigeromorph centipede (Myriapoda: Chilopoda), Fulmenocursor tenax gen. et sp. nov., is described from the Lower Cretaceous (Aptian) Crato Formation of north-east Brazil. Previously described fossil Scutigeromorpha are known from Dominican and Baltic amber, the Carboniferous (Westphalian D) Francis Creek Shale of Mazon Creek, Illinois, the Silurian and Devonian of Britain, and the Devonian of New York State. [source]


A stem-group caecilian (Lissamphibia: Gymnophiona) from the Lower Cretaceous of North Africa

PALAEONTOLOGY, Issue 2 2001
Susan E. Evans
Of living amphibian groups, the limbless burrowing caecilians are amongst the most highly specialised, but are the least known. Their fossil record is extremely poor, leaving unresolved questions as to their origins, relationships and early distribution. We describe here caecilian remains from a Lower Cretaceous (Berriasian) microfossil locality near Anoual, Morocco. This material represents the second oldest record for the group, after the Jurassic Eocaecilia of North America, and the earliest caecilian record for Gondwana. It forms the basis of a new genus, Rubricacaecilia, which appears slightly more derived than Eocaecilia, but lacks major features of crown-group taxa. We support the use of Apoda Oppel, 1811 for the crown-group alone, and Gymnophiona Rafinesque 1814 for the clade comprising stem-group taxa + Apoda. [source]


Detrital zircon geochronology of Carboniferous,Cretaceous strata in the Lhasa terrane, Southern Tibet

BASIN RESEARCH, Issue 3 2007
Andrew L. Leier
ABSTRACT Sedimentary strata in the Lhasa terrane of southern Tibet record a long but poorly constrained history of basin formation and inversion. To investigate these events, we sampled Palaeozoic and Mesozoic sedimentary rocks in the Lhasa terrane for detrital zircon uranium,lead (U,Pb) analysis. The >700 detrital zircon U,Pb ages reported in this paper provide the first significant detrital zircon data set from the Lhasa terrane and shed new light on the tectonic and depositional history of the region. Collectively, the dominant detrital zircon age populations within these rocks are 100,150, 500,600 and 1000,1400 Ma. Sedimentary strata near Nam Co in central Lhasa are mapped as Lower Cretaceous but detrital zircons with ages younger than 400 Ma are conspicuously absent. The detrital zircon age distribution and other sedimentological evidence suggest that these strata are likely Carboniferous in age, which requires the existence of a previously unrecognized fault or unconformity. Lower Jurassic strata exposed within the Bangong suture between the Lhasa and Qiangtang terranes contain populations of detrital zircons with ages between 200 and 500 Ma and 1700 and 2000 Ma. These populations differ from the detrital zircon ages of samples collected in the Lhasa terrane and suggest a unique source area. The Upper Cretaceous Takena Formation contains zircon populations with ages between 100 and 160 Ma, 500 and 600 Ma and 1000 and 1400 Ma. Detrital zircon ages from these strata suggest that several distinct fluvial systems occupied the southern portion of the Lhasa terrane during the Late Cretaceous and that deposition in the basin ceased before 70 Ma. Carboniferous strata exposed within the Lhasa terrane likely served as source rocks for sediments deposited during Cretaceous time. Similarities between the lithologies and detrital zircon age-probability plots of Carboniferous rocks in the Lhasa and Qiangtang terranes and Tethyan strata in the Himalaya suggest that these areas were located proximal to one another within Gondwanaland. U,Pb ages of detrital zircons from our samples and differences between the geographic distribution of igneous rocks within the Tibetan plateau suggest that it is possible to discriminate a southern vs. northern provenance signature using detrital zircon age populations. [source]


Current Knowledge of Mesozoic Coleoptera from Daohugou and Liaoning (Northeast China)

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 4 2010
Alexander G. KIREJTSHUK
Abstract: The present paper is devoted to an overview on fossil Coleoptera studied from Inner Mongolia, Daohugou (Middle Jurassic, Jiulongshan Formation) and Liaoning (Upper Jurassic-Lower Cretaceous, Yixian Formation) deposited in Chinese collections. As a result, species of the tribe Sperchopsini and Hydrophilini from Hydrophilidae, families and subfamilies Silphidae, Syndesinae from Lucanidae, Pleocomidae, Trogidae, Trogissitidae, Pyrochroidae, Diaperinae from Tenebrionidae, and Cerambycidae were first registered in the Mesozoic and some families were defined as new. It was shown that many superfamilies represented in the Recent Fauna were formed within the Middle Jurassic and Lower Cretaceous. The materials examined confirm the hypothesis that Cucujiformian beetles are a younger group than other infraordera of Polyphaga (Staphyliniformia and Elateriformia) and, therefore, they appeared in the fossil record only in the late Mesozoic. It was shown and confirmed that most superfamilies appeared in the fossil records before Cucujoidea. The synonymy of Notocupes Ponomarenko, 1964; Sinocupes Lin, 1976, syn. nov.; Amblomma Tan, Ren et Liu 2005, syn. nov.; Euryomma Tan, Ren et Shih, 2006, syn. nov., non Stein, 1899 and Ovatocupes Tan et Ren, 2006, syn. nov.; synonymy of Tetraphalerus Waterhouse, 1901 and Odontomma Tan, Ren et Ge 2006, syn. nov.; and synonymy of Priacmopsis Ponomarenko, 1966 and Latocupes Tan et Ren, 2006, syn. nov. are proposed. Sinorhombocoleus papposus Tan et Ren, 2009 is transferred from the family Rhombocoleidae to Schizophoridae. Cervicatinius complanus Tan, Ren et Shih, 2007 and Forticatinius elegans Tan, Ren et Shih, 2007 are transferred from the family Catiniidae (suborder Archostemata) to superfamily Cleroidea (suborder Polyphaga: first among the family Peltidae and second as a closely related group to the latter family). The family Parandrexidae is transferred from the superfamily Cucujoidea to Cleroidea. The ecological circumstances of the past ecosystems and hypotheses of historical development of the order Coleoptera are discussed. The age of faunas examined is considered. The list of the taxa described from Daohugou and Liaoning is compiled. [source]


Jurassic Amber in Lebanon

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 4 2010
Dany AZAR
Abstract: Reports of amber predating the Lower Cretaceous are unusual and scarce; they mostly refer to amber pieces of millimetric dimension. In the present study, we report the discovery of 10 new outcrops of Jurassic amber in Lebanon. Some of these had large centimetric-sized pieces of amber. The new localities are described, amber is characterized, and its infrared spectra given. Although the new Jurassic amber yielded to date no more than fungal inclusions, this material is significant and promising. The discovery of several Jurassic outcrops provides crucial information on the prevailing paleoenvironment of that time. [source]


A New Species of Cathayornis from the Lower Cretaceous of Inner Mongolia, China and Its Stratigraphic Significance

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 6 2008
LI Jianjun
Abstract: An incomplete postcranial avian skeleton is described from the Lower Cretaceous Jingchuan Formation of Otog Banner of western Inner Mongolia and referred to a new species of Cathayornis, C. chabuensis sp. nov. This is the first report of a Cathayornis from outside Liaoning Province. The new discovery indicates that Cathayornis coexisted with Otogornis genghisi, and a more detailed comparison between these two enantiornithine genera shows that Otogornis represents a more primitive genus than Cathayornis. Our analyses further indicate that Cathayornis is an arboreal bird. The discovery of a Cathayornis from this region also confirms that the avian fossil-bearing Jingchuan Formation is comparable to the Jiufotang Formation of the upper Jehol Group in western Liaoning, and should be referred to the middle-late Early Cretaceous. [source]


The evolutionary history of krill inferred from nuclear large subunit rDNA sequence analysis

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2001
SIMON N. JARMAN
Early events in the speciation history of krill (Malacostraca: Euphausiacea), an abundant group of extant pelagic crustaceans, were studied with slowly evolving nuclear DNA sequences (large subunit ribosomal DNA, 28S rDNA). Krill have no fossil record, so very little is known about their paleobiology. The timing of past speciation events in krill was estimated by comparing change in their 28S rDNA to change in the 28S rDNA of their close relatives that do have a fossil record. Relationships between krill genera were also studied by phylogenetic analysis of partial 28S rDNA sequences. The analyses estimated the time that the last common ancestor of the krill family Euphausiidae lived to be the lower Cretaceous about 130 million years ago (Mya). Two lineages of krill survived the end Cretaceous extinctions 65 Mya and the modern genera of krill were established before the end of the Palaeogene 23 Mya. [source]