Jurassic-Lower Cretaceous Research Articles

Structural context of the paleogeography of the Cenomanian-Turonian anoxic event in the eastern Atlas basins of the Maghreb

The regional Cenomanian-Turonian (C/T) structural framework of surface and subsurface coupled with subsidence data inferred from palegeographic and organic-rich C/T isopachus maps, generated in this work, from several basins, wells and outcrops of Tunisia and eastern Algeria were investigated and provide constraints on the structural and sedimentary evolution of this part of the southern Tethyan margin during the C/T times. This period is characterized by the development of extensional structures with tilted blocks and grabens, bounded listric normal faults. Subsidence during C/T time led to the accumulation of a thick sequence of laminated black shales and marls (up to 80 m thick in northwestern Tunisia and about 100 m thick in the Aures-Kef trough in northeastern Algeria). Sharp variations in thickness and facies towards the north and northeast indicate that basin subsidence was driven by regional tectonic movements along NW-SE, NE-SW and east-west trending normal faults issued from Tethyan rifting of the Upper Jurassic-Lower Cretaceous. The reduction of emerged areas since the Cenomanian inferred from the generated palaeogeographic map is demonstrated. The overall evolution is also maintained by halokinesis of Triassic salt creating subsident rim-synclines, where organic-rich facies prevail.

Glabrimycetoporus amoenus, a new tachyporine genus and species of Mesozoic Staphylinidae (Coleoptera) from Liaoning, China

A new genus and species of well-preserved fossil Staphylinidae is described and illustrated. Glabrimycetoporus amoenus Yue, Zhao & Ren, gen. et sp. nov. is assigned to the tribe Mycetoporini in the subfamily Tachyporinae based on the following characters: head more or less inserted into prothorox, the tenth abdominal tergite broad and oblong; antennal insertions exposed and located anterior to a line drawn between anterior edges of eyes; body strongly tapered to the narrow head and abdominal apex. The specimen was discovered in the Upper Jurassic–Lower Cretaceous Yixian Formation of Beipiao City, Liaoning Province, NE China.

Proportion of Mesozoic sedimentary rock types: data from northern Eurasia reveal similarities to North American patterns

The Mesozoic stratigraphic record of northern Eurasia includes a total of 1,739 formations. The proportion of conglomerate, sandstone + siltstone, shale, carbonates, evaporites, siliceous rocks, and volcanics + volcaniclastics among sedimentary complexes are evaluated for each epoch of the Mesozoic. Sandstone, shale, and conglomerate occur in 86%, 71%, and 42% of formations respectively. Less common are carbonates (28%) and volcanics and volcaniclastics (24%), whereas evaporites and siliceous rocks are rare (< 5%). The proportion of particular sedimentary rock types fluctuates throughout the Mesozoic. The proportion of sandstone + siltstone changes quite similarly to that of shale. A comparison of stratigraphic data from northern Eurasia and North America reveals some similarities, including a Lower Triassic increase in the conglomerate proportion, a Middle-Upper Triassic increase in the proportion of siliceous rocks, Upper Triassic-Lower Jurassic and Upper Jurassic-Lower Cretaceous “clastic spikes”, and a Middle-Upper Jurassic “carbonate-evaporite spike”. They may reflect any global-scale processes. Increases in clastic deposition coincided with eustatic lowstands, whereas voluminous accumulation of carbonates and evaporites tended to coincide with global sea-level rises. It remains unclear whether global climate was responsible for changes in the proportion of sedimentary rock types.

Integrated biostratigraphy and regional correlations of Upper Jurassic–lowermost Cretaceous series in northern Tunisia

Integrated biostratigraphy and palaeogeographical interpretations of Upper Jurassic–Lower Cretaceous (Callovian–Berriasian) successions are synthesised on the basis of published data and our recent investigations of key sections from the “Tunisian Dorasale” (TD) and “Tunisian Trough” (TT) domains of northern Tunisia. After a revised biostratigraphy had been proposed for the “rosso ammonitico” series, bed-by-bed sampling led to a radiolarian-based first direct dating of the partly coeval biosiliceous series in the TT. Upward within the Jurassic column, an integrated biostratigraphy (ammonites, calpionellids and associated biomicrofacies) allowed precise biozonation for the Kimmeridgian–middle Berriasian interval. The heterogeneity of the Late Jurassic facies in northern Tunisia is the result of two main geodynamical and palaeogeographical events. The first corresponds to the fragmentation of the initial Early Jurassic platform linked to Tethyan rifting. The second event, coeval to the radiolarian-bearing series of the TT, is expressed by a significant deepening in north-west Tunisian palaeoenvironments. During Kimmeridgian–Tithonian times, previous troughs evolved back into carbonate platforms. Within the Maghrebian Belt, Upper Jurassic–lowermost Cretaceous series comprising three major facies groups are easily correlated; minor differences in age are interpreted as due to local tectonic control. Regional correlations confirm, on the one hand, a common geological history for the external segments of the African margin and, on the other hand, a distinct palaeogeographical evolution of the inner domain including the “Dorsales calcaires” and ancient massifs, both being separated by intermediate flysch zone segments.

Melanterite and szomolnokite as weathering products of pyrite from the Bazhenovo Formation

Weathering of pyrite in the core recovered from black shales of the Bazhenovo Formation (Upper Jurassic-Lower Cretaceous) in the West Siberian marine basin promoted the successive formation of melanterite (FeSO4 · 7H2O) and szomolnokite (FeSO4 · H2O). Szomolnokite was detected in West Siberia for the first time.

Rock magnetic and paleointensity results from Mesozoic baked contacts of Armenia

Abstract Samples were obtained from three baked contacts and one lava flow along the upper Turonian-lower Coniacian Tovuz section, two baked contacts along the upper Coniacian-lower Santonian Paravakar section in the northern part of Armenia, and three baked contacts along the Titonian-Valanginian Kafan section in southern Armenia. A total of 130 samples were studied. Updated mean paleomagnetic poles were calculated for the Upper Cretaceous Tovuz-Paravakar sections (65.6°N, 162.2°E, A95 = 4.3, paleolatitude = 27.0 ± 3.4°) and the Upper Jurassic-Lower Cretaceous Kafan section (61.7°N, 158.9°E, A95 = 4.8°, paleolatitude = 24.7 ± 3.8°). Paleointensity determinations could be estimated from two of the upper Cretaceous and three of the Upper Jurassic-Lower Cretaceous baked contacts, corresponding to a 30% success rate. The mean virtual dipole moments obtained were low (1.7-5.5 × 1022 A m2), which is in agreement with data published by Bol’shakov and Solodovnikov (1981a, 1983) for the same sections (3.0-4.4 × 1022 A m2). Our results support the hypothesis of the Mesozoic Dipole Low, even though the overall data are widely dispersed.

A new genus and species of Chresmodidae (Insecta: Gryllones) from Upper Jurassic-Lower Cretaceous of Yixian Formation, Inner Mongolia, China

A new genus and species of Chresmodidae (Insecta: Gryllones) from Upper Jurassic-Lower Cretaceous of Yixian Formation, Inner Mongolia, China

Lithology of the Upper Jurassic Lower Cretaceous (Tithonian-Lower Berriasian) Aj-Petri reef complex (southern Ukraine, the Crimea Mountains)

The following paper presents a lithological characterization of Tithonian-Lower Berriasian limestones from the southern Crimea Mountains. Both the massive and bedded limestones forming the Aj-Petri reef-complex comprise four main lithofacies groups: stromatoporoid-microbial frame- stone-bindstone, bioclastic wackestone-floatstone, oncoidal packstone and oolitic and intraclastic grainstone-rudstone. Due to strong cementation, the specific lithofacies groups appear as macro- scopically homogenic, massive Aj-Petri limestones. The rocks were deposited in shallow, subtidal and intertidal environments related to the shallowing sea level trends. The principal reef-builders were stromatoporoids (demosponges), microbialites and microencrusters, which produced numerous stromatoporoid-microbial patch-reefs and biostromes. These rocks, along with detrital sediments form the main part of the Aj-Petri reef. A dominance of stromatoporoid bioconstructions may reflect the restricted environmental conditions, which limited or even precluded the growth of other reef- building organisms, particularly the corals. Among the most important factors facilitating the vigorous growth of stromatoporoid bioconstructions in such environments could have been their high tolerance for changing depositional conditions resulting in dense packing of skeletons. Such packing, in turn, might have facilitated the intensive growth of microencrusters in the interskeletal spaces, particularly Bacinella and Thaumatoporella, enabling rapid lithification of the initial, stromato- poroidal reef frame supporting the development of a rigid framework, resistive to intensive erosion. During periods of more stable environmental conditions, intensive microbialites growth took place which enabled the binding of specific patch-reefs and peri-reefal deposits, resulting in the formation of the massive Aj-Petri limestone monolith as it appears today.

Oil-source correlation of the pre-Tertiary in the Huanghua Depression: Insights from stable carbon isotopes and molecular markers

Stable carbon isotopes were used together with molecular markers to constrain genetic relationships between sandstone extracts and potential source rocks in the pre-Tertiary in the Huanghua Depression, North China. Comparison of the extracts from Permo-Carboniferous terrigenous mudstones and Ordovician marine carbonates indicated that their prominent differences are in stable carbon isotopes, molecular markers and thermal maturity. Although the extracts of the Mesozoic and Lower Permian Xiashihezi Formation sandstones have some similar isotopic characteristics, molecular markers data provide a good correlation between the Upper Jurassic-Lower Creta-ceous oils and the Upper Carboniferous Taiyuan Formation mudstones, and between the Lower Permian Xiashihezi Formation oils and the Lower Permian mudstones. The results showed that the Upper Jurassic-Lower Cretaceous sandstone oils were derived chiefly from the Upper Carboniferous Taiyuan Formation terrigenous mudstones and that the Lower Permian Xiashihezi Formation oils were sourced from the Lower Permian Shanxi Formation and Xiashihezi Formation terrigenous mudstones.

The role of skeletal and nonskeletal biogenic material in the accumulation of organic matter of the Bazhenov Formation

Organic matter of the Upper Jurassic-Lower Cretaceous highly carbonaceous black-shale Bazhenov Formation in the central part of the West Siberian sea basin is composed of predominantly sapropelic planktonogenic material, which was earlier assumed to have derived from siliceous-skeletal microorganisms (first of all, radiolarians) and nonskeletal ones (bacteria and algae). Comparative analysis for organic carbon in the formation rocks and in radiolarites and radiolarian oozes from some other areas showed that the siliceous-skeletal organisms make up <1% of the organic matter of the Bazhenov Formation. This is confirmed by correlation analysis of two main types of Bazhenov rocks — siliceous-argillaceous (bazhenovites) and argillaceous (mudstones), — which showed the absence of correlation between the contents of organic carbon and quartz (which is mainly authigenic) for both rocks.

A new genus and species of Chresmodidae (Insecta: Gryllones) from Upper Jurassic-Lower Cretaceous of Yixian Formation, Inner Mongolia, China

A new genus with a new species of Chresmodidae (Insecta: Gryllones), Sinochresmoda magnicornia gen. et sp. nov., including specimens of male, female and nymph, is described and illustrated. These fossils were collected from the Upper Jurassic-Lower Cretaceous of Yixian Formation of Liutiaogou Village, Inner Mongolia (Nei Mongol Autonomous Region), China. Both male and female possess wings, and have sexual dimorphism in antenna. Antennae of male are highly specialized and horn-shaped, incurvated as horn with the scape strongly expanded, and the first segment of the flagella incurvated as a pair of brackets, while antennae of female are normally filiform. Wings of the new species are short, not exceeding the length of the abdomen. Fringe hairs along the wing margins, a unique feature for Chresmodidae, are dense, wavy and bundled together. Nymphs and adults probably lived in the same environment. In addition, one specimen demonstrates the extraordinary structure of tarsus with a high number of “tarsomeres”, which has been reported in other species of this family.

The basaltic volcanic rocks in the Tuyon Basin, NW China: Petrogenesis and tectonic implications

The Tuyon basin is located near the crossing of the Tien Shan orogenic belt, the Western Kunlun fold system and the TarimAlashan blocks. The crossing of two lithospheric scale fault, the Talas-Ferghana dextral strike-slip fault and the NE extended South Tien Shan strike-slip fault, is just at the southern margin of the Tuyon basin. Therefore, many geoscientists all over the world have been attracted to petrogenesis of the Cenozoic basaltic volcanic rocks in the Tuyon basin and their tectonic implications. According to previous researches, the basalts emplaced within the Tuyon basin are of two units, the lower basalts and the upper basalts, aged 120~110 Ma and 70.4~36.6 Ma respectively. All these basalts are classified as alkali series, enriched in potassium, and considered as a result of a small plume probably rooted at a shallow level in the asthenosphere. Our new works on the igneous rocks in the Tuyon basin suggest that the so-called lower basalts are preserved as a series of cone dikes, which are emplaced in Jurassic-Lower Cretaceous sedimentary rocks; the upper basalts are formed as a series of volcanic eruptions, including calderas, ring dikes, necks and volcanic cones. For example, there are three volcanic cones in the line between the Kuvt cone and Bilebluk cone. We have discovered basaltic intrusive units in Jurassic sandstone and conglomerate strata. The basaltic extrusive units have the same occurrence with the early Cretaceous sediments, but uncomfortably overlain by the Paleogene sedimentary rocks. Therefore, the Tuyon basin is a compound volcanic basin, including series of volcanic eruptions with lavas and subvolcanic rocks, rather than it has two-layer structure consisted of two igneous units. Our investigations indicate that the basaltic rocks are mainly of dark gray, massive structure and porphyritic texture. The basaltic extrusive rocks are developed as columnar joint structure, vesicular structure and amygdaloidal structure. Most of volcanic rocks within Tuyon basin contain phenocrysts such as olivine, clinopyroxene and plagioclase, and occasionally phlogopite, amphibole and apatite. Olivine belongs to chrysolite circled by fine-grained aggregate of magnetite and talc. Most of olivine phenocrysts have been altered into iddingsite and talc. The clinopyroxene mainly belongs to augite, which characterize hourglass structure and zoned texture. The plagioclase phenocrysts have more content of anorthite. They are mainly andesine and occasional labradorite, but rare in zoned texture. The matrix minerals are clinopyroxene, plagioclase, magnetite and volcanic glass, and mainly formed tholeiitic texture, occasionally intergranular texture and vitrophyric. Therefore, the Cenozoic volcanic rocks in the Tuyon basin show characteristics of alkali series, and suggest that the region may was at extensional condition. In the Arhesaiordy volcanic-sedimentary sequences there are five basaltic sills intruded into the Jurassic sedimentary deposits. Many megacrysts have been found in the lowest basaltic layer, such as augite, phlogopite, amphibole and anorthoclasite. From the same layer we have collected lots of the deep-seated xenoliths including peridotite, granulite, pyroxenite, gneiss and so on. In the other four layers, the number of megacrysts and deep-seated xenoliths has been decreased quickly. There are also lots of deep-seated xenoliths in the Tasgeler caldera. Therefore, basaltic magma has the characteristics of rapid ascent. Consequently, the basaltic volcanic rocks in the Tuyon basin are formed direct from primary magma, which is rare affected by fractional crystallization.

Theropod Dinosaur Trackways from the Lower Cretaceous of the Chacarilla Formation, Chile

We describe sixteen theropod dinosaur trackways from site III (Lower Cretaceous?) of the Quebrada Cha- carilla in the Chacarilla Formation (Jurassic-Lower Cretaceous), northern Chile. The trackbed belongs to a meandering river environment, with recurrent track assemblages. We fi nd that the main direction of the ichnites from site III parallels that of water fl ow. Two theropod footprint morphotypes are recognized: A) digit II and IV occupying about 0.5 times the total footprint length, and B) digit II and IV occupying less than 0.35 times the total footprint length. We estimate similar speed (~7 km/h) for the two parallel theropod trackways of morphotype A, suggesting synchro nized walking. We also describe some of the largest theropod footprints from South America (>60 cm), which are all of morphotype B.

Two new species ofRetiskenea? (Gastropoda: Neomphalidae) from Lower Cretaceous hydrocarbon-seep carbonates of northern California

Two new Mesozoic gastropod species, provisionally attributed to the minute (height &lt; 5 mm) coiled neomphalid genusRetiskenea?, are described from three geographically isolated, Early Cretaceous, hydrocarbon seep-carbonate sites at Wilbur Springs, Rice Valley, and Cold Fork of Cottonwood Creek, northern California (USA). A fourth paleo-seep locality at Paskenta, of probable Upper Jurassic age, also yielded a single specimen of a morphologically similar microgastropod that may be a neomphalid with affinities to the Lower Cretaceous specimens described herein. the limestone lenses are ~2-260 m in length, ~1-5 m in diameter, and surrounded by forearc siliciclastics of bathyal turbidites or sedimentary serpentinites in the Upper Jurassic to Lower Cretaceous (Tithonian-Albian) Great Valley Group and its equivalents. the Lower Cretaceous microgastropods are tentatively placed inRetiskenea?based on similar shell characters: size, globose shape, inflated reticulate protoconch, number and distinct inflation of the body whorls, and fine, prosocline sculpture of the final body whorl. the fossils occur in carbonate microbialites that formed in seafloor sediments during archaeal anaerobic oxidation of methane in the zone of bacterial sulfate reduction, associated with H2S- and CH4-rich fluid seepage. the CaliforniaRetiskenea?fossils commonly are found in gregarious clusters, or closely affiliated with thin worm tubes or, in one case, a larger gastropod.These Mesozoic records increase the total known species attributable to this cold-seep endemic genus from two to four. Its spatial and temporal distribution thus may have spanned ~9,000 km around the Pacific Rim from at least ~133 m.y. to the present in 10 subduction-related seep sites from California (possibly Upper Jurassic-Lower Cretaceous), Washington (middle Eocene-Upper Oligocene), and modern offshore Oregon, the eastern Aleutians, and the Japan Trench. If the generic placement of these microgastropod fossils is correct, the California records are the oldest-known occurrences ofRetiskenea, consistent with an estimated minimum Mesozoic origin for the 'hot vent' Neomphalidae, as inferred from molecular analyses published on other living members of the family.

Uppermost Jurassic-Lower Cretaceous carbonate deposits from Fara San Martino (Maiella, Italy): biostratigraphic remarks

The Uppermost Jurassic-Lower Cretaceous limestone succession in the Maiella region of Italy has been investigated in a profile covering more than 400 m stratigraphical thickness at Fara San Martino. The succession mainly consists of peritidal limestones, intertidal and supratidal sequences being dominant, together with subtidal lagoonal facies. As a consequence, the microfossil assemblages are generally poorly developed, Microfossils occur within the subtidal lagoonal facies of this suite of restricted sediments. This feature led us to recognise five informal biostratigraphic intervals, which are facies related - instead of biozones, each of the intervals being characterized by specific micropaleontological associations. The occurrence and/or disappearance of some marker microfossils were used as references for separating these intervals. Based on these markers, the Uppermost Jurassic-Lower Cretaceous carbonate deposits from Maiella region may be correlated with similar deposits from the Apennines and from other regions in the perimediterranean area.

Iodine concentrations of soils near Trabzon, Turkey: a region of endemic goiter

Iodine contents of soils developed over the major rock formations of the northern zone of the Eastern Pontide Tectonic Belt (Northeastern Turkey) have been investigated with respect to soil-parent rock relationship, effect of topography, elevation, and climate to construe its effect on the health of the local population. Samples were collected from the A and B horizons of the soils developed over the major stratigraphic units constituting the eastern Pontides, including the Lower Basic Complex of Jurassic-Lower Cretaceous age, the Berdiga limestone (Jurassic-lower Cretaceous), the Dagbasi granitoid (Upper Cretaceous), volcano-sedimentary sequence of Upper Cretaceous age, ore-bearing and barren dacites of Upper Cretaceous age, and Neogene alkaline basalts. Chemical analyses of soil samples indicate significantly lower iodine abundances for all the soils studied (5–28 ppm) in comparison to the average abundance of iodine in analogous soils of other parts of the world (22–93 ppm). The concentration of iodine in soils developed over the same geologic formation decrease with increasing elevation. In certain cases, this decrease may reach up to 70%. Goiter is highly common throughout this region in Turkey. The results of this study suggest that the iodine deficiency of region’s soils may be a principal underlying cause for this area of Turkey being an endemic goiter region.

M. Bubick and M. A. Kaminski, Editors, 2004. Proceedings of the Sixth International Workshop on Agglutinated Foraminifera.: Grzybowski Foundation Special Publication, 8, 485 p. + x pp., ISBN: 83-912385-4-7, Price: 49, order from Micropaleontology Project, 256 Fifth Avenue, 4th Floor, New York, N.Y. 10001 [tel. 1-212-481-2997] or direct from Special Publications Editor (email: m.Kaminski@ucl.ac.uk). The Grzybowski Foundation, c/o Geological Museum,

Review Article| December 01, 2006 M. Bubick and M. A. Kaminski, Editors, 2004. Proceedings of the Sixth International Workshop on Agglutinated Foraminifera.: Grzybowski Foundation Special Publication, 8, 485 p. + x pp., ISBN: 83-912385-4-7, Price: £49, order from Micropaleontology Project, 256 Fifth Avenue, 4th Floor, New York, N.Y. 10001 [tel. 1-212-481-2997] or direct from Special Publications Editor (email: m.Kaminski@ucl.ac.uk). The Grzybowski Foundation, c/o Geological Museum, Jagiellonian University, ul. Oleandry 2a, 30-063 Krakow, Poland. William A. Berggren William A. Berggren Department of Geology and Geophysics, Woods Hole Oceangraphic Institution, Woods Hole, MA 02543 and Department of Geological Sciences, Rutgers University, Busch Campus, Wright-Riemann Laboratories, Piscataway, NJ 08854 Search for other works by this author on: GSW Google Scholar Author and Article Information William A. Berggren Department of Geology and Geophysics, Woods Hole Oceangraphic Institution, Woods Hole, MA 02543 and Department of Geological Sciences, Rutgers University, Busch Campus, Wright-Riemann Laboratories, Piscataway, NJ 08854 Publisher: Micropaleontology Press First Online: 06 Mar 2017 Online Issn: 0026-2803 Print Issn: 1937-2795 © 2006 The Micropaleontology Project, Inc. Micropaleontology (2006) 52 (6): 553–554. https://doi.org/10.2113/gsmicropal.52.6.553 Article history First Online: 06 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation William A. Berggren; M. Bubick and M. A. Kaminski, Editors, 2004. Proceedings of the Sixth International Workshop on Agglutinated Foraminifera.: Grzybowski Foundation Special Publication, 8, 485 p. + x pp., ISBN: 83-912385-4-7, Price: £49, order from Micropaleontology Project, 256 Fifth Avenue, 4th Floor, New York, N.Y. 10001 [tel. 1-212-481-2997] or direct from Special Publications Editor (email: m.Kaminski@ucl.ac.uk). The Grzybowski Foundation, c/o Geological Museum, Jagiellonian University, ul. Oleandry 2a, 30-063 Krakow, Poland.. Micropaleontology 2006;; 52 (6): 553–554. doi: https://doi.org/10.2113/gsmicropal.52.6.553 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyMicropaleontology Search Advanced Search The study of agglutinated benthic foraminifera continues to thrive as this latest contribution from the Grzybowski Foundation testifies. The proceedings of the latest Workshop in Prague (2001) represent a distillation of the 43 lectures (23 of which dealt with the Cretaceous and 9 with the Upper Jurassic-Lower Cretaceous) presented in the newly refurbished conference center of the Charles University at the medieval Carolinum complex. The diversity of topics and sheer size (465 pages!) of this volume preclude a detailed analysis of the papers in this volume. Inasmuch as the papers are presented in alphabetic order rather than being grouped by... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Phylogeny of fireflies (Coleoptera: Lampyridae) inferred from mitochondrial 16S ribosomal DNA, with references to morphological and ethological traits

Abstract Global environments changed greatly during the Late Jurassic and Early Cretaceous, Particularly during the Jurassic Cretaceous boundary interval. Separation of the world into Tethyan, Boreal and other biogeographic realms complicates international correlation, and even the pelaagic ammonites cannot play their characteristic role of principle correlation criteria. In the Boreal and North Pacific realms, the Late Jurassic and Cretaceous buchiid bivalve zones have very good calibration to Boreal ammonite zones, which, in turn, have approximate correlation to Tethyan ammonite zones. Therefore, buchiid bivalves provide a means to identify Upper Jurassic-Lower Cretaceous stages and the Jurassic Cretaceous boundary interval. The base of the Buchia unschensis Zone is roughly coincident with the Boreal ammonite Craspedites exoticus subzone, Upper Volgian Craspedites okensis Zone, which in turn closely corresponds to the base of the Tethyan ammonite basal Berriasian Berriasella jacobi Zone. The top of the ...

Status of “ Trigonia ventricosa” (Bivalvia) from the Upper Jurassic–Lower Cretaceous of Kutch, western India: Kitchin's unfinished synthesis

Kitchin first reported Trigonia ventricosa (Krauss) from Kutch in 1903. The populations he studied came from different localities and stratigraphic horizons, but erroneous information on Kutch geology initially led him to believe that all his material was obtained only from Late Tithonian strata. He noted, however, that populations of different areas had distinct morphological characters and biofacies associations and later expressed uncertainties about the homogeneity of the Kutch species. Trigonia ventricosa was later included in Pisotrigonia van Hoepen (subfamily Pterotrigoniinae). Our field investigation and study of numerous specimens collected from different localities as well as the material examined by previous workers (Kitchin and Cox) reveal that populations of “ T. ventricosa” are, in fact, found at four distinct stratigraphic levels ranging from Late Tithonian to Aptian in age; they differ both morphologically and morphometrically, allowing the recognition of four distinct species, some of which are temporally separated by as much as seven million years. The species, in ascending stratigraphical order, are Pisotrigonia kitchini sp. nov., P. umiensis sp. nov., P. ventricosa (Krauss) and P. ghuneriensis sp. nov. The Pterotrigoniinae are apparently polyphyletic since Pterotrigonia has myophorellian ancestry while Pisotrigonia has megatrigonian affinities; they are stratigraphically heterochronous and evolved initially in two different palaeobiogeographic provinces. During the Valanginian, Pterotrigonia and Pisotrigonia shared the same biogeographic area and showed character displacement. Pisotrigonia species in Kutch evolved anagenetically with initial increase in body size followed finally by size decrease. The mode of evolution is punctuational and was induced by heterochrony.

The new sauropod from Spain: Galveosaurus or Galvesaurus?

On August 11 th , 2005 I published a paper in which I described a new genus and species of sauropod dinosaur from the Upper Jurassic-Lower Cretaceous of Galve, Spain: Galveosaurus herreroi. Unfortunately, four months later, a second paper based on the same dinosaur remains was published by different authors. In this second paper, the authors gave the specimens a similar binomial name to the name I gave (with a difference of one letter, an “o”): Galvesaurus herreroi. In that paper, available on-line in pdf format from January 2006, the authors not only ignored my work, but they included a publication date: 1st July, 2005. Nevertheless, the article is included in the issue 15 th of July-December, as could be read in every page of that work. The issue was published on 18 th December 2005, but according to the ICZN code (articles 21 and 23), the date of publication of the Barco et al. (2005) paper should be considered as December 31 st , 2005 and based on the Principle of Priority, the name Galveosaurus herreroi Sánchez-Hernández, 2005 has priority and Galvesaurus herreroi Barco, Canudo, Cuenca-Bescós and Ruíz-Omeñaca, 2005 should be considered as a junior synonym of the former and therefore, an invalid name.